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Mochizuki M.,Aoyama Gakuin University | Mochizuki M.,Japan Science and Technology Agency
Physical Review Letters | Year: 2015

We theoretically find that in the multiferroic chiral magnet Cu2OSeO3 resonant magnetic excitations are coupled to the collective oscillation of the electric polarization, and thereby attain simultaneous activity to the ac magnetic field and ac electric field. Because of the interference between these magnetic and electric activation processes, this material hosts a gigantic magnetochiral dichroism for microwaves, that is, a directional dichroism at gigahertz frequencies in the Faraday geometry. The absorption intensity of a microwave differs by as much as ∼30% depending on whether its propagation direction is parallel or antiparallel to the external magnetic field. © 2015 American Physical Society.

Wang L.,Japan National Institute of Materials Science | Yamauchi Y.,Japan National Institute of Materials Science | Yamauchi Y.,Waseda University | Yamauchi Y.,Japan Science and Technology Agency
Chemistry of Materials | Year: 2011

Our recent study has shown that Pluronic F127 triblock copolymer can assist the formation of unique Au@Pd@Pt triple-layered core-shell-structured nanoparticles consisting of a Au core, a Pd inner layer, and nanoporous Pt outer shell (J. Am. Chem. Soc.2010, 132, 13636). Pluronic F127 is a very typical surfactant that is commonly used in the synthesis of mesoporous silica and carbon, but Pluronic F127 is very rarely used for the synthesis of metallic nanostructures. Herein, we expand our previous concept to further demonstrate that such interesting Au@Pd@Pt nanoparticles can be easily synthesized by using poly(vinylpyrrolidone) (PVP) instead of Pluronic F127. PVP is a very typical capping and structure-directing agent used for the synthesis of various metallic nanostructures. The present synthetic route using a PVP-based aqueous solution will greatly contribute to the further design of multilayered metallic nanoarchitectures with designed compositions and desired functions. Furthermore, a detailed investigation on the electrocatalytic activity of the trimetallic nanoparticles is also performed. © 2011 American Chemical Society.

Nagamori T.,University of Tsukuba | Marumoto K.,University of Tsukuba | Marumoto K.,Japan Science and Technology Agency
Advanced Materials | Year: 2013

A clear correlation between the number of accumulated holes (N spin) in poly(3-hexylthiophene) (P3HT) and the deterioration of the performance is observed in polymer solar cells under simulated solar irradiation. The sites of hole accumulation with deep trapping levels are formed at the interfaces between P3HT:[6,6]-phenyl C61-butyric acid methyl ester (PCBM) and poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) layers. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kuzuya A.,Kansai University | Kuzuya A.,Japan Science and Technology Agency | Ohya Y.,Kansai University
Accounts of Chemical Research | Year: 2014

ConspectusEight years have passed since the striking debut of the DNA origami technique (Rothemund, P. W. K. Nature 2006, 440, 297-302), in which long single-stranded DNA is folded into a designed nanostructure, in either 2D or 3D, with the aid of many short staple strands. The number of proposals for new design principles for DNA origami structures seems to have already reached a peak. It is apparent that DNA origami study is now entering the second phase of creating practical applications. The development of functional nanomechanical molecular devices using the DNA origami technique is one such application attracting significant interest from researchers in the field. Nanomechanical DNA origami devices, which maintain the characteristics of DNA origami structures, have various advantages over conventional DNA nanomachines. Comparatively high assembly yield, relatively large size visible via atomic force microscopy (AFM) or transmission electron microscopy (TEM), and the capability to assemble multiple functional groups with precision using multiple staple strands are some of the advantages of the DNA origami technique for constructing sophisticated molecular devices.This Account describes the recent developments of such nanomechanical DNA origami devices and reviews the emerging target of DNA origami studies. First, simple "dynamic" DNA origami structures with transformation capability, such as DNA origami boxes and a DNA origami hatch with structure control, are briefly summarized. More elaborate nanomechanical DNA origami devices are then reviewed. The first example describes DNA origami pinching devices that can be used as "single- molecule" beacons to detect a variety of biorelated molecules, from metal ions at the size of a few tens of atomic mass number units to relatively gigantic proteins with a molecular mass greater than a hundred kilodaltons, all on a single platform. Clamshell-like DNA nanorobots equipped with logic gates can discriminate different cell lines, open their shell, and bind to their target. An intelligent DNA origami "sheath" can mimic the function of suppressors in a transcription regulation system to control the expression of a loaded gene. DNA origami "rolls" are created to construct precisely arranged plasmonic devices with metal nanoparticles. All of their functions are derived from their nanomechanical movement, which is programmable by designing the DNA sequence or by using the significant repository of technical achievements in nucleic acid chemistry. Finally, some studies on detailed structural parameters of DNA origami or their mechanical properties in nanoscale are discussed, which may be useful and inspiring for readers who intend to design new nanomechanical DNA origami devices. © 2014 American Chemical Society.

Kuramochi Y.,Kitasato University | Kamiya M.,Kitasato University | Ishida H.,Kitasato University | Ishida H.,Japan Science and Technology Agency
Inorganic Chemistry | Year: 2014

N,N-Dimethylacetamide (DMA) was used for the first time as the reaction solvent in the photocatalytic reduction of CO2. DMA is highly stable against hydrolysis and does not produce formate even if it is hydrolyzed. We report the catalytic activities of [Ru(bpy)2(CO)2](PF 6)2 (bpy = 2,2′-bipyridine) in the presence of [Ru(bpy)3](PF6)2 as a photosensitizer and 1-benzyl-1,4-dihydronicotinamide (BNAH) as an electron donor in DMA/water. In the photochemical CO2 reduction, carbon monoxide (CO) and formate are catalytically produced, while dihydrogen (H2) from the reduction of water is scarcely evolved. We verified that BNAH is oxidized to afford BNA dimers during the photocatalyses in DMA/water. The plots of the production for the CO2 reduction versus the water content in DMA/water show that the 10 vol % water content gives the highest amount of the reduction products, whose reaction quantum yields (φ′) are determined to be 11.6% and 3.2% for CO and formate, respectively. The results are compared with those in the N,N-dimethylformamide (DMF)/water system, which has been typically used as the solvent system for the CO2 reduction. © 2014 American Chemical Society.

Ohno T.,Tohoku University | Ohno T.,Japan Science and Technology Agency | Samukawa S.,Tohoku University
Applied Physics Letters | Year: 2015

Resistive switching in a Cu/Ta2O5/Pt structure that consisted of a few nanometer-thick Ta2O5 film was demonstrated. The Ta2O5 film with thicknesses of 2-5 nm was formed with a combination of Ta metal film deposition and neutral oxygen particle irradiation at room temperature. The device exhibited a bipolar resistive switching with a threshold voltage of 0.2 V and multilevel switching operation. © 2015 AIP Publishing LLC.

Ueno K.,Hokkaido University | Ueno K.,Japan Science and Technology Agency | Misawa H.,Hokkaido University
NPG Asia Materials | Year: 2013

This paper presents recent investigations of plasmon-enhanced photoelectric conversion and water oxidation by visible and nearinfrared light irradiation. Since the discovery of the Honda-Fujishima effect in 1972, significant efforts have been devoted to lengthening the light-energy conversion wavelength. In this context, plasmonic photoelectric conversion has been recently demonstrated at visible-to-near-infrared wavelengths without deteriorating photoelectric conversion by employing titanium dioxide (TiO2) single-crystal photoelectrodes, in which gold nanorods are elaborately arrayed on the surface. A potassium perchlorate aqueous solution was employed as an electrolyte solution without additional electron donors; thus, water molecules provided the electrons. The stoichiometric evolution of oxygen and hydrogen peroxide as a result of the four-or two-electron oxidation of water molecules, respectively, was accomplished with near-infrared light irradiation using the plasmonic optical antenna effect. As there is very little overpotential for water oxidation, these results constitute a significant advancement in this field. In addition, this photoelectric conversion system could potentially be employed in artificial photosynthesis systems that exceed the photosynthetic capabilities of plants by allowing for photoconversion over a wide range of wavelengths. © 2013 Nature Publishing Group.

Yuan J.-J.,Kawamura Institute of Chemical Research | Jin R.-H.,Japan Science and Technology Agency
Langmuir | Year: 2010

We report using the substrates covered with self-organized linear polyethylenimine (PEI) layer as biomimetic template to direct the formation of high-quality titania coat with well-defined nanofiber-based network structure. The titania deposition was simply achieved by dipping the PEI substrates into aqueous solution of titanium bislactate under ambient conditions. We found that crystalline PEI layer on the substrates is important for achieving titania coat with nanofiber-based structure. Compared to the titania powder formed by solution deposition, the interface-mediated nanostructured titania exhibited dramatically improved thermostability with being able to maintain anatase phase in majority even at 900 °C. Moreover, the nanostructures of titania coat could be well controlled by simply adjusting the formation conditions of crystalline PEI layer on substrates. Because of high-efficiency photocatalysis of anatase titania, the nanostructured surface exhibited good photoresponsive surface wettability through hydrophobic modification and light irradiation. © 2010 American Chemical Society.

Ohmatsu K.,Nagoya University | Hara Y.,Nagoya University | Ooi T.,Nagoya University | Ooi T.,Japan Science and Technology Agency
Chemical Science | Year: 2014

A method for the in situ generation of ion-paired chiral ligands from simple salts of ammonium phosphines and chiral Brønsted acids under phase-transfer conditions is established. The exploitation of this method in combinatorial ligand screening has enabled the rapid identification of the optimal ion-paired chiral ligand for the palladium-catalyzed asymmetric allylic alkylation of benzo[b]thiophen-2(3H)-ones. © 2014 the Partner Organisations.

Maeda K.,University of Tokyo | Maeda K.,Japan Science and Technology Agency | Higashi M.,Hokkaido University | Siritanaratkul B.,University of Tokyo | And 2 more authors.
Journal of the American Chemical Society | Year: 2011

Strontium niobium oxynitride (SrNbO2N) particles were coated on fluorine-doped tin oxide (FTO) glass and examined as a photoelectrode for water splitting under visible light in a neutral aqueous solution (Na 2SO4, pH ≈ 6). SrNbO2N, which has a band gap of ca. 1.8 eV, acted as an n-type semiconductor and generated an anodic photocurrent assignable to water oxidation upon irradiation with visible-light photons with wavelengths of up to 700 nm, even without an externally applied potential. Under visible light (λ > 420 nm) with an applied potential of +1.0-1.55 V vs RHE, nearly stoichiometric H2 and O2 evolution was achieved using a SrNbO2N/FTO electrode modified with colloidal iridium oxide (IrO2) as a water oxidation promoter. This study presents the first example of photoelectrochemical water splitting involving an n-type semiconductor with a band gap smaller than 2.0 eV that does not require an externally applied potential. © 2011 American Chemical Society.

Maeda K.,University of Tokyo | Maeda K.,Japan Science and Technology Agency | Ohno T.,University of Tokyo | Domen K.,University of Tokyo
Chemical Science | Year: 2011

Nanoparticulate oxides consisting of copper (Cu) and chromium (Cr) were studied as noble-metal-free cocatalysts for photocatalytic water splitting. The structure of the Cu-Cr mixed oxide dispersed on a solid solution of GaN and ZnO (referred to as GaN: ZnO hereafter) was characterized by highresolution transmission electron microscopy (HR-TEM), X-ray absorption fine-structure (XAFS) spectroscopy, and electrochemical measurements. The mixed-oxide nanoparticle was an effective promoter of photocatalytic overall water splitting on GaN: ZnO, and was loaded by impregnation from an aqueous solution containing Cu(NO3)2·3H2O and Cr(NO3)3·9H2O followed by calcination in air. Impregnation of GaN: ZnO with 1.5 wt% Cu and 2.0 wt% Cr followed by calcination at 623 K for 1 h provided the highest photocatalytic activity, while catalysts modified with either Cu-oxide or Cr-oxide showed little activity. The activity of this photocatalyst was shown to be strongly dependent on the generation of Cu(II)-Cr(III) mixed-oxide nanoparticles with optimal composition and coverage. The results of electrochemical measurements and photocatalytic reactions also indicated that Cu(II)-Cr(III) mixed-oxide nanoparticles on GaN: ZnO are resistant to both the photoreduction of O2 and water formation from H2 and O2, which are undesirable reverse reactions in overall water splitting. © The Royal Society of Chemistry 2011.

Shiga N.,Japan Science and Technology Agency | Shiga N.,Tokyo Institute of Technology | Takeuchi M.,University of Tokyo
New Journal of Physics | Year: 2012

A new method is proposed to reduce the frequency noise of a local oscillator to the level of white phase noise by maintaining (not destroying by projective measurement) the coherence of the ensemble pseudo-spin of atoms over many measurement cycles. This method, which we call 'atomic phase lock (APL)', uses weak measurement to monitor the phase in the Ramsey method and repeat the cycle without initialization of the phase. APL will achieve white phase noise as long as the noise accumulated during dead time and the decoherence are smaller than the measurement noise. A numerical simulation confirmed that with APL, the Allan deviation is averaged down at a maximum rate that is proportional to the inverse of the total measurement time, τ -1. In contrast, current atomic clocks that use projection measurement suppress the noise only to the white frequency noise level, in which case the Allan deviation scales as τ -1/2. Faraday rotation is one way to achieve weak measurement for APL. The strength of Faraday rotation with 171Yb + ions trapped in a linear rf-trap is evaluated, and the performance of APL is discussed. The main source of decoherence is a spontaneous emission, induced by the probe beam for Faraday rotation measurement. The Faraday rotation measurement can be repeated until the decoherence becomes comparable to the signal-to-noise ratio of the measurement. The number of cycles for a realistic experimental parameter is estimated to be ∼100. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Sugino R.P.,Graduate University for Advanced Studies | Innan H.,Graduate University for Advanced Studies | Innan H.,Japan Science and Technology Agency
Molecular Biology and Evolution | Year: 2012

A genome must locate its coding genes on the chromosomes in a meaningful manner with the help of natural selection, but the mechanism of gene order evolution is poorly understood. To explore the role of selection in shaping the current order of coding genes and their cis-regulatory elements, a comparative genomic approach was applied to the baker's yeast Saccharomyces cerevisiae and its close relatives. S. cerevisiae have experienced a whole-genome duplication followed by an extensive reorganization process of gene order, during which a number of new adjacent gene pairs appeared.We found that the proportion of new adjacent gene pairs in divergent orientation is significantly reduced, suggesting that such new divergent gene pairsmay be disfavoredmost likely because their coregulationmay be deleterious. It is also found that such new divergent gene pairs have particularly long intergenic regions. These observations suggest that selection specifically worked against deletions in intergenic regions of new divergent gene pairs, perhaps because they should be physically kept away so that they are not coregulated. It is indicated that gene regulation would be one of the major factors to determine the order of coding genes. © The Author 2011.

Gao S.,Hokkaido University | Ueno K.,Hokkaido University | Ueno K.,Japan Science and Technology Agency | Misawa H.,Hokkaido University
Accounts of Chemical Research | Year: 2011

Efficient solar energy conversion has been vigorously pursued since the 1970s, but its large-scale implementation hinges on the availability of high-efficiency modules. For maximum efficiency, it is important to absorb most of the incoming radiation, which necessitates both efficient photoexcitation and minimal electron-hole recombination. To date, researchers have primarily focused on the latter difficulty: finding a strategy to effectively separate photoinduced electrons and holes. Very few reports have been devoted to broadband sunlight absorption and photoexcitation. However, the currently available photovoltaic cells, such as amorphous silicon, and even single-crystal silicon and sensitized solar cells, cannot respond to the wide range of the solar spectrum. The photoelectric conversion characteristics of solar cells generally decrease in the infrared wavelength range. Thus, the fraction of the solar spectrum absorbed is relatively poor. In addition, the large mismatch between the diffraction limit of light and the absorption cross-section makes the probability of interactions between photons and cell materials quite low, which greatly limits photoexcitation efficiency. Therefore, there is a pressing need for research aimed at finding conditions that lead to highly efficient photoexcitation over a wide spectrum of sunlight, particularly in the visible to near-infrared wavelengths.As characterized in the emerging field of plasmonics, metallic nanostructures are endowed with optical antenna effects. These plasmonic antenna effects provide a promising platform for artificially sidestepping the diffraction limit of light and strongly enhancing absorption cross-sections. Moreover, they can efficiently excite photochemical reactions between photons and molecules close to an optical antenna through the local field enhancement. This technology has the potential to induce highly efficient photoexcitation between photons and molecules over a wide spectrum of sunlight, from visible to near-infrared wavelengths. In this Account, we describe our recent work in using metallic nanostructures to assist photochemical reactions for augmenting photoexcitation efficiency.These studies investigate the optical antenna effects of coupled plasmonic gold nanoblocks, which were fabricated with electron-beam lithography and a lift-off technique to afford high resolution and nanometric accuracy. The two-photon photoluminescence of gold and the resulting nonlinear photopolymerization on gold nanoblocks substantiate the existence of enhanced optical field domains. Local two-photon photochemical reactions due to weak incoherent light sources were identified. The optical antenna effects support the unprecedented realization of (i) direct photocarrier injection from the gold nanorods into TiO2 and (ii) efficient and stable photocurrent generation in the absence of electron donors from visible (450 nm) to near-infrared (1300 nm) wavelengths. © 2011 American Chemical Society.

Kakuta T.,Osaka University | Takashima Y.,Osaka University | Nakahata M.,Osaka University | Otsubo M.,Osaka University | And 3 more authors.
Advanced Materials | Year: 2013

Supramolecular hydrogels formed by a host-guest interaction show self-healing properties. The cube-shaped hydrogels with β-cyclodextrin and adamantane guest molecules mend after being broken. The hydrogels sufficiently heal to form a single gel, and the initial strength is restored. Although contact between a freshly cut and uncut surface does not mend the gels, two freshly cut surfaces selectively mend. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kobayashi A.,Hokkaido University | Kobayashi A.,Japan Science and Technology Agency | Kato M.,Hokkaido University
European Journal of Inorganic Chemistry | Year: 2014

Vapochromic materials that show reversible color change driven by vapor adsorption/desorption have drawn significant attention because of their potential applications in chemical sensors and chemical-switching modules. Among the vapochromic coordination complexes reported so far, a series of square-planar PtII complexes has been studied and represents one of the most promising systems for practical chemical sensors. For such systems, the color of the complexes strongly depends not only on the ligand-field splitting, but also on the intermolecular distance between the PtII ions. This microreview presents recent results of vapochromic complexes centered on one-dimensionally stacked PtII systems from the viewpoint of the origin of their vapochromic behavior. The design of vapochromic materials has been facilitated because several useful chromophores, including metallophilic interaction between PtII ions, have been developed. However, it is still challenging to realize a specifically sensitive and selective response to targeted vapors. This review focuses on strategies to achieve assembled PtII complexes with selective vapochromic responses. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biju V.,Japan National Institute of Advanced Industrial Science and Technology | Biju V.,Japan Science and Technology Agency
Chemical Society Reviews | Year: 2014

As prepared nanomaterials of metals, semiconductors, polymers and carbon often need surface modifications such as ligand exchange, and chemical and bioconjugate reactions for various biosensor, bioanalytical, bioimaging, drug delivery and therapeutic applications. Such surface modifications help us to control the physico-chemical, toxicological and pharmacological properties of nanomaterials. Furthermore, introduction of various reactive functional groups on the surface of nanomaterials allows us to conjugate a spectrum of contrast agents, antibodies, peptides, ligands, drugs and genes, and construct multifunctional and hybrid nanomaterials for the targeted imaging and treatment of cancers. This tutorial review is intended to provide an introduction to newcomers about how chemical and bioconjugate reactions transform the surface of nanomaterials such as silica nanoparticles, gold nanoparticles, gold quantum clusters, semiconductor quantum dots, carbon nanotubes, fullerene and graphene, and accordingly formulate them for applications such as biosensing, bioimaging, drug and gene delivery, chemotherapy, photodynamic therapy and photothermal therapy. Nonetheless, controversial reports and our growing concerns about toxicity and pharmacokinetics of nanomaterials suggest the need for not only rigorous in vivo experiments in animal models but also novel nanomaterials for practical applications in the clinical settings. Further reading of original and review articles cited herein is necessary to buildup in-depth knowledge about the chemistry, bioconjugate chemistry and biological applications of individual nanomaterials. This journal is © The Royal Society of Chemistry.

Mochida S.,Kumamoto University | Mochida S.,Japan Science and Technology Agency
FEBS Journal | Year: 2014

Progression into M phase requires inhibition of heterotrimeric PP2A containing the regulatory B55 subunit (PP2A-B55) as well as the activation of cyclin-dependent kinase 1 (Cdk1). α-endosulfine (ENSA)/cyclic AMP-regulated 19 kDa phosphoprotein (ARPP-19) family proteins phosphorylated at S67 by Greatwall kinase bind and inhibit PP2A-B55. This study shows that endogenous kinases phosphorylate not only S67 but also two additional sites in ENSA (T28 and S109) with different kinetics at different cell-cycle stages in Xenopus laevis intact cells and cell-free egg extracts. When assayed in vitro, these phosphorylations had qualitatively and/or quantitatively different effects on inhibition of PP2A-B55 by ENSA. Structural analyses revealed that the most-conserved middle region of ENSA containing S67 physically interacts with PP2A-B55 at the interface of the B55 and C subunits, where the catalytic centre of PP2A is located. As non-phosphorylated ENSA has an intrinsic potential for PP2A-B55 inhibition, these three phosphorylations differentially affect physical interaction of the middle region of ENSA with PP2A-B55. These results suggest that the two additional phosphorylation sites together with S67 allow ENSA to function as a 'stepwise tuner' for PP2A-B55, which may be regulated by multiple cellular signals, rather than a simple 'on/off' switch. © 2013 FEBS.

Harada A.,Osaka University | Harada A.,Japan Science and Technology Agency | Takashima Y.,Osaka University | Nakahata M.,Osaka University
Accounts of Chemical Research | Year: 2014

ConspectusCyclodextrins (CDs) have many attractive functions, including molecular recognition, hydrolysis, catalysis, and polymerization. One of the most important uses of CDs is for the molecular recognition of hydrophobic organic guest molecules in aqueous solutions. CDs are desirable host molecules because they are environmentally benign and offer diverse functions.This Account demonstrates some of the great advances in the development of supramolecular materials through host-guest interactions within the last 10 years. In 1990, we developed topological supramolecular complexes with CDs, polyrotaxane, and CD tubes, and these preparation methods take advantage of self-organization between the CDs and the polymers. The combination of polyrotaxane with αCD forms a hydrogel through the interaction of αCDs with the OH groups on poly(ethylene glycol). We categorized these polyrotaxane chemistries within main chain type complexes. At the same time, we studied the interactions of side chain type supramolecular complexes with CDs. In these systems the guest molecules modified the polymers and selectively formed inclusion complexes with CDs. The systems that used low molecular weight compounds did not show such selectivity with CDs. The multivalency available within the complex cooperatively enhances the selective binding of CD with guest molecules via the polymer side chains, a phenomenon that is analogous to binding patterns observed in antigen-antibody complexes.To incorporate the molecular recognition properties of CDs within the polymer side chains, we first prepared stimuli-responsive sol-gel switching materials through host-guest interactions. We chose azobenzene derivatives for their response to light and ferrocene derivatives for their response to redox conditions. The supramolecular materials were both redox-responsive and self-healing, and these properties resulted from host-guest interactions. These sol-gels with built in switches gave us insight for creating materials that were self-healing or could serve as artificial muscle.Furthermore, we developed another self-healing material with CD inclusion complexes that showed selective self-healing properties after its surface was cut. These CD self-healing materials do not include chemical cross-linkers; instead the inclusion complex of CDs with guest molecules stabilized the material's strength. However, by introducing chemical cross-linkers into the hydrogels, we produced materials that could expand and contract. The chemical cross-linked hydrogels with responsive groups bent in response to external stimuli, and the cross-linkers controlled the ratio of inclusion complexes. Furthermore, we used the molecular recognition of CDs to achieve macroscopic self-assemblies, and this chemistry can direct these macroscopic objects into even larger aggregated structures. As we have demonstrated, reversible host-guest interactions have tremendous potential for the creation of a wide variety of functional materials. © 2014 American Chemical Society.

Takeshita D.,Japan National Institute of Advanced Industrial Science and Technology | Tomita K.,Japan National Institute of Advanced Industrial Science and Technology | Tomita K.,Japan Science and Technology Agency
Nature Structural and Molecular Biology | Year: 2012

Core Qβ replicase comprises the Qβ virus-encoded RNA-dependent RNA polymerase (β-subunit) and the host Escherichia coli translational elongation factors EF-Tu and EF-Ts. The functions of the host proteins in the viral replicase are not clear. Structural analyses of RNA polymerization by core Qβ replicase reveal that at the initiation stage, the 3′-adenine of the template RNA provides a stable platform for de novo initiation. EF-Tu in Qβ replicase forms a template exit channel with the β-subunit. At the elongation stages, the C-terminal region of the β-subunit, assisted by EF-Tu, splits the temporarily double-stranded RNA between the template and nascent RNAs before translocation of the single-stranded template RNA into the exit channel. Therefore, EF-Tu in Qβ replicase modulates RNA elongation processes in a distinct manner from its established function in protein synthesis. © 2012 Nature America, Inc. All rights reserved.

Kataoka N.,Kyoto University | Hioki H.,Kyoto University | Kaneko T.,Kyoto University | Nakamura K.,Kyoto University | Nakamura K.,Japan Science and Technology Agency
Cell Metabolism | Year: 2014

Summary Psychological stress-induced hyperthermia (PSH) is a fundamental autonomic stress response observed in many mammalian species. Here we show a hypothalamomedullary, glutamatergic neural pathway for psychological stress signaling that drives the sympathetic thermogenesis in brown adipose tissue (BAT) that contributes to PSH. Using in vivo drug nanoinjections into rat brain and thermotelemetry, we demonstrate that the rostral medullary raphe region (rMR) and dorsomedial hypothalamus (DMH) mediate a psychosocial stress-induced thermogenesis in BAT and PSH. Functional neuroanatomy indicates that the DMH functions as a hub for stress signaling, with monosynaptic projections to the rMR for sympathetic outputs and to the paraventricular hypothalamic nucleus for neuroendocrine outputs. Optogenetic experiments showed that the DMH-rMR monosynaptic pathway drives BAT thermogenesis and cardiovascular responses. These findings make an important contribution to our understanding of the central autonomic circuitries linking stress coping with energy homeostasis - potentially underlying the etiology of psychogenic fever, a major psychosomatic symptom. © 2014 Elsevier Inc.

Ando J.,Osaka University | Ando J.,Japan Science and Technology Agency | Fujita K.,Osaka University | Smith N.I.,Osaka University | And 2 more authors.
Nano Letters | Year: 2011

Dynamic SERS imaging inside a living cell is demonstrated with the use of a gold nanoparticle, which travels through the intracellular space to probe local molecular information over time. Simultaneous tracking of particle motion and SERS spectroscopy allows us to detect intracellular molecules at 65 nm spatial resolution and 50 ms temporal resolution, providing molecular maps of organelle transport and lisosomal accumulation. Multiplex spectral and trajectory imaging will enable imaging of specific dynamic biological functions such as membrane protein diffusion, nuclear entry, and rearrangement of cellular cytoskeleton. © 2011 American Chemical Society.

Kim J.Y.,Kyushu University | Yasuda T.,Kyushu University | Yasuda T.,Japan Science and Technology Agency | Yang Y.S.,Kyushu University | Adachi C.,Kyushu University
Advanced Materials | Year: 2013

Bifunctional star-burst amorphous molecular materials displaying both efficient solid-state luminescence and high hole-transport properties are developed in this study. A high external electroluminescence quantum efficiency up to 5.9% is attained in OLEDs employing the developed amorphous materials. It is revealed that the spontaneous horizontal orientation of these light-emitting molecules in their molecular-condensed states leads to a remarkable enhancement of the electroluminescence efficiencies and carrier-transport properties. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zhou Y.,Kanazawa University | Taima T.,Kanazawa University | Taima T.,Japan Science and Technology Agency | Kuwabara T.,Kanazawa University | Takahashi K.,Kanazawa University
Advanced Materials | Year: 2013

A cascade-type small-molecule organic photovoltaic cell using a crystalline diindenoperylene film as a nanostructured template is demonstrated. This cell architecture simultaneously realizes organic nanostructure and cascade energy concepts, which significantly improves the photocurrent generation and fill factor, leading to a power conversion efficiency of 5.2 ± 0.3%. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Myoken Y.,Japan Science and Technology Agency
International Journal of Technology Management | Year: 2010

The world economic environment has dramatically changed through IT revolution, which leaves the government to seek a new role in the driving seat for setting industrial and technological policies. In order to maintain the competitive edge derived from scientific and technological innovation it is important for the government to adopt the demand-side policy towards commercialisation of technology-based SMEs and start-ups. The Japanese government has discussed the significance of an 'innovation orientated new approach for public procurement'. Through drawing comparisons with procurement strategies employed by the US, the UK and the Netherlands the paper proposes: (1) intermediary professional actors to appraise prototype technologies; (2) interactive dialogues between suppliers and users before tendering; (3) fair and transparent competition focussing on new social and economic values of emerging technologies are the absolute essence of public procurement for innovation. Copyright © 2010 Inderscience Enterprises Ltd.

Takaoka Y.,Kyoto University | Ojida A.,Kyushu University | Hamachi I.,Kyoto University | Hamachi I.,Japan Science and Technology Agency
Angewandte Chemie - International Edition | Year: 2013

The modification of proteins with synthetic probes is a powerful means of elucidating and engineering the functions of proteins both invitro and in live cells or invivo. Herein we review recent progress in chemistry-based protein modification methods and their application in protein engineering, with particular emphasis on the following four strategies: 1)the bioconjugation reactions of amino acids on the surfaces of natural proteins, mainly applied in test-tube settings; 2)the bioorthogonal reactions of proteins with non-natural functional groups; 3)the coupling of recognition and reactive sites using an enzyme or short peptide tag-probe pair for labeling natural amino acids; and 4)ligand-directed labeling chemistries for the selective labeling of endogenous proteins in living systems. Overall, these techniques represent a useful set of tools for application in chemical biology, with the methods 2-4 in particular being applicable to crude (living) habitats. Although still in its infancy, the use of organic chemistry for the manipulation of endogenous proteins, with subsequent applications in living systems, represents a worthy challenge for many chemists. Labels of the reconstruction: Chemical modification of proteins with synthetic probes is a powerful means of elucidating protein functions in live cells and of influencing these functions. New reactions that can be successfully applied in living systems represent a worthy challenge to organic chemistry, especially as the labeling and manipulation of endogenous proteins in their natural habitats is currently at an early stage. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kawamata T.,University of Tokyo | Kawamata T.,Tokyo Medical University | Tomari Y.,University of Tokyo | Tomari Y.,Tokyo Medical University | Tomari Y.,Japan Science and Technology Agency
Trends in Biochemical Sciences | Year: 2010

It is well established that 20- to 30-nt small RNAs, including small interfering RNAs, microRNAs and Piwi-interacting RNAs, play crucial roles in regulating gene expression and control a surprisingly diverse array of biological processes. These small RNAs cannot work alone: they must form effector ribonucleoprotein complexes - RNA-induced silencing complexes (RISCs) - to exert their function. Thus, RISC assembly is a key process in small RNA-mediated silencing. Recent biochemical analyses of RISC assembly, together with new structural studies of Argonaute, the core protein component of RISC, suggest a revised view of how mature RISC, which contains single-stranded guide RNA, is built from small RNAs that are born double-stranded. © 2010 Elsevier Ltd.

Yamaguchi H.,Osaka University | Kobayashi Y.,Osaka University | Kobayashi R.,Osaka University | Takashima Y.,Osaka University | And 3 more authors.
Nature Communications | Year: 2012

The formation of effective and precise linkages in bottom-up or top-down processes is important for the development of self-assembled materials. Self-assembly through molecular recognition events is a powerful tool for producing functionalized materials. Photoresponsive molecular recognition systems can permit the creation of photoregulated self-assembled macroscopic objects. Here we demonstrate that macroscopic gel assembly can be highly regulated through photoisomerization of an azobenzene moiety that interacts differently with two host molecules. A photoregulated gel assembly system is developed using polyacrylamide-based hydrogels functionalized with azobenzene (guest) or cyclodextrin (host) moieties. Reversible adhesion and dissociation of the host gel from the guest gel may be controlled by photoirradiation. The differential affinities of α-cyclodextrin or β-cyclodextrin for the trans-azobenzene and cis-azobenzene are employed in the construction of a photoswitchable gel assembly system. © 2012 Macmillan Publishers Limited. All rights reserved.

Ishizu H.,University of Tokyo | Ishizu H.,Keio University | Siomi H.,Keio University | Siomi M.C.,University of Tokyo | And 2 more authors.
Genes and Development | Year: 2012

PIWI-interacting RNAs (piRNAs) are endogenous small noncoding RNAs that act as guardians of the genome, protecting it from invasive transposable elements in the germline. Animals lacking piRNA functions show defects in gametogenesis and exhibit sterility. Their descendants are also predisposed to inheriting mutations. Thus, the piRNA pathway has evolved to repress transposons posttranscriptionally and/or transcriptionally. A growing number of studies on piRNAs have investigated piRNA-mediated gene silencing, including piRNA biogenesis. However, piRNAs remain the most enigmatic among all of the silencing-inducing small RNAs because of their complexity and uniqueness. Although piRNAs have been previously suggested to be germline-specific, recent studies have shown that piRNAs also play crucial roles in nongonadal cells. Furthermore, piRNAs have also recently been shown to have roles in multigenerational epigenetic phenomena in worms. The purpose of this review is to highlight new piRNA factors and novel insights in the piRNA world. © 2012 by Cold Spring Harbor Laboratory Press.

Miyawaki A.,RIKEN | Miyawaki A.,Japan Science and Technology Agency | Shcherbakova D.M.,Yeshiva University | Verkhusha V.V.,Yeshiva University
Current Opinion in Structural Biology | Year: 2012

In the last decade, a number of red fluorescent proteins (RFPs) that emit orange, red, and far-red fluorescence have been isolated from anthozoans (corals), and developed through directed molecular evolution. An attractive property possessed by some RFPs is that their red fluorescence can be turned on or modulated by illumination at specific wavelengths. Recent progress in the development of RFPs has been accompanied with detailed studies of chromophore chemistry. A thorough understanding of the molecular mechanisms involved in the post-translational modifications of red chromophores would enable scientists to design RFPs with the desired properties to advance imaging applications. This article provides a broad perspective on the chemistry and applications of RFPs. © 2012 Elsevier Ltd.

Egami H.,RIKEN | Sodeoka M.,RIKEN | Sodeoka M.,Japan Science and Technology Agency
Angewandte Chemie - International Edition | Year: 2014

The trifluoromethyl group is found in many synthetic bioactive compounds, and the difunctionalization of a C=C bond, as a powerful strategy for the construction of compounds with various functional groups, has been intensively investigated. Therefore, the difunctionalizing trifluoromethylation of alkenes has attracted growing interest because of the potential of the products as building blocks for bioactive molecules. In this review, we focus on recent advances in the trifluoromethylation of alkenes with concomitant introduction of additional functional groups. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gilroy S.,University of Wisconsin - Madison | Suzuki N.,Sophia University | Miller G.,Bar - Ilan University | Choi W.-G.,University of Wisconsin - Madison | And 4 more authors.
Trends in Plant Science | Year: 2014

Systemic signaling pathways enable multicellular organisms to prepare all of their tissues and cells to an upcoming challenge that may initially only be sensed by a few local cells. They are activated in plants in response to different stimuli including mechanical injury, pathogen infection, and abiotic stresses. Key to the mobilization of systemic signals in higher plants are cell-to-cell communication events that have thus far been mostly unstudied. The recent identification of systemically propagating calcium (Ca2+) and reactive oxygen species (ROS) waves in plants has unraveled a new and exciting cell-to-cell communication pathway that, together with electric signals, could provide a working model demonstrating how plant cells transmit long-distance signals via cell-to-cell communication mechanisms. Here, we summarize recent findings on the ROS and Ca2+ waves and outline a possible model for their integration. © 2014 Elsevier Ltd.

Kobayashi T.,Japan Science and Technology Agency | Kobayashi T.,Ishikawa Prefectural University | Nishizawa N.K.,Ishikawa Prefectural University
Plant Science | Year: 2014

The transcription of genes involved in iron acquisition in plants is induced under iron deficiency, but our understanding of iron sensors and signals remains limited. Iron Deficiency-responsive Element-binding Factor 1 (IDEF1) and Hemerythrin motif-containing Really Interesting New Gene- and Zinc-finger proteins (HRZs)/BRUTUS (BTS) have recently emerged as candidate iron sensors because of their functions as potent regulators of iron deficiency responses and their iron-binding properties. IDEF1 is a central transcriptional regulator of graminaceous genes involved in iron uptake and utilization, predominantly during the early stages of iron deficiency. HRZs/BTS are E3 ubiquitin ligases and negative regulators of iron deficiency responses in both graminaceous and non-graminaceous plants. Rice OsHRZ1 and OsHRZ2 are also potent regulators of iron accumulation. Characterizing these putative iron sensors also provides clues to understanding the nature of iron signals, which may involve ionized iron itself, other metals, oxygen, redox status, heme and iron-sulfur clusters, in addition to metabolites affected by iron deficiency. Systemic iron responses may also be regulated by phloem-mobile iron and its chelators such as nicotianamine. Iron sensors and signals will be identified by demonstration of signal transmission by IDEF1, HRZs/BTS, or unknown factors. © 2014 The Authors.

Inada N.,Nara Institute of Science and Technology | Ueda T.,University of Tokyo | Ueda T.,Japan Science and Technology Agency
Plant and Cell Physiology | Year: 2014

Membrane trafficking functions in the delivery of proteins that are newly synthesized in the endoplasmic reticulum (ER) to their final destinations, such as the plasma membrane (PM) and the vacuole, and in the internalization of extracellular components or PM-associated proteins for recycling or degradative regulation. These trafficking pathways play pivotal roles in the rapid responses to environmental stimuli such as challenges by microorganisms. In this review, we provide an overview of the current knowledge of plant membrane trafficking and its roles in plant-microbe interactions. Although there is little information regarding the mechanism of pathogenic modulation of plant membrane trafficking thus far, recent research has identified many membrane trafficking factors as possible targets of microbial modulation. © 2014 The Author.

Oku M.,Kyoto University | Sakai Y.,Kyoto University | Sakai Y.,Japan Science and Technology Agency
Antioxidants and Redox Signaling | Year: 2012

Significance: Development of redox-sensing fluorescent proteins (redox probe proteins) have enabled live imaging of the physiological redox state within a cell, generating new strategies for detecting changes in the redox state during developmental, pathogenic, and aging processes. Several of the probe proteins utilize their characteristic redox-sensing segments as linkers in between two fluorophores, where structural alternations of the segments lead to changes in FRET efficiencies across the fluorophores. In this review we summarize two types of novel FRET-based redox probe proteins, namely redox linker (RL)-derived probes and Redoxfluor. Recent Advances: After these FRET-based redox probe proteins were generated, their responsiveness toward redox-related compounds as well as toward reactive oxygen species or reducing stimuli was investigated in vitro. Notably, both the RL-derived probe and Redoxfluor were found to directly respond to the redox state of glutathione, a main redox-formulating compound, showing a promising property for their use in subsequent in vivo analyses. Redoxfluor was not only used for redox sensing in the cytoplasm, but also utilized for assessing the redox state within peroxisomes. Critical Issues: In contrast to "one-fluorophore" redox probes such as roGFP and rxYFP proteins, whose usage has been established and widely expanded to various experimental systems, FRET-based redox probes were invented very recently and their applications to in vivo studies are still in their infancy. Future Directions: FRET-based redox probes provide novel approaches for redox sensing that are complementary to other methodologies. © 2012, Mary Ann Liebert, Inc.

Kono N.,University of Tokyo | Arai H.,University of Tokyo | Arai H.,Japan Science and Technology Agency
Traffic | Year: 2015

Vitamins are compounds that are essential for the normal growth, reproduction and functioning of the human body. Of the 13 known vitamins, vitamins A, D, E and K are lipophilic compounds and are therefore called fat-soluble vitamins. Because of their lipophilicity, fat-soluble vitamins are solubilized and transported by intracellular carrier proteins to exert their actions and to be metabolized properly. Vitamin A and its derivatives, collectively called retinoids, are solubilized by intracellular retinoid-binding proteins such as cellular retinol-binding protein (CRBP), cellular retinoic acid-binding protein (CRABP) and cellular retinal-binding protein (CRALBP). These proteins act as chaperones that regulate the metabolism, signaling and transport of retinoids. CRALBP-mediated intracellular retinoid transport is essential for vision in human. α-Tocopherol, the main form of vitamin E found in the body, is transported by α-tocopherol transfer protein (α-TTP) in hepatic cells. Defects of α-TTP cause vitamin E deficiency and neurological disorders in humans. Recently, it has been shown that the interaction of α-TTP with phosphoinositides plays a critical role in the intracellular transport of α-tocopherol and is associated with familial vitamin E deficiency. In this review, we summarize the mechanisms and biological significance of the intracellular transport of vitamins A and E. In this review, we summarize the mechanisms and biological significance of the intracellular transport of vitamins A and E. Intracellular binding proteins of these vitamins participate in the metabolism, signaling and cellular influx/efflux of the vitamins by transporting their ligands to appropriate targets. We also highlight the mechanism of vectorial transport of vitamin E in liver cells, which may be a general strategy for intracellular lipid transport. © 2014 The Authors. Traffic published by John Wiley & Sons Ltd.

Uyanik M.,Nagoya University | Ishihara K.,Nagoya University | Ishihara K.,Japan Science and Technology Agency
ACS Catalysis | Year: 2013

The Baeyer-Villiger (BV) oxidation of carbonyl compounds to the corresponding esters or lactones is one of the most important transformations. We recently introduced a highly efficient and selective LiB(C6F 5)4- or Ca[B(C6F5)4] 2-catalyzed BV oxidation of ketones with aqueous hydrogen peroxide to give the corresponding lactones in high yield. In this perspective article, we focus on our discovery and the development of BV oxidation reactions and cascade oxidative transformations through representative metal catalysts and organocatalysts. © 2013 American Chemical Society.

Pan S.,Waseda University | Shibata T.,Waseda University | Shibata T.,Japan Science and Technology Agency
ACS Catalysis | Year: 2013

Over the past few years, iridium complexes have been widely used in the direct functionalization of unactivated bonds. In the presence of iridium catalysts, inactive C-H and N-H bonds have been transformed into C-C and N-C bonds in dehydrative alkylation using alcohols, allylation using allyl carbonates, and alkylation using alkenes. Enantioselective variants of some reactions have also been reported. © 2013 American Chemical Society.

Takashima T.,University of Tokyo | Hashimoto K.,University of Tokyo | Hashimoto K.,Japan Science and Technology Agency | Nakamura R.,University of Tokyo
Journal of the American Chemical Society | Year: 2012

The development of Mn-oxide electrocatalysts for the oxidation of H 2O to O 2 has been the subject of intensive researches not only for their importance as components of artificial photosynthetic systems, but also as O 2-evolving centers in photosystem II. However, limited knowledge of the mechanisms underlying this oxidation reaction hampers the ability to rationally design effective catalysts. Herein, using in situ spectroelectrochemical techniques, we demonstrate that the stabilization of surface-associated intermediate Mn 3+ species relative to charge disproportionation is an effective strategy to lower the overpotential for water oxidation by MnO 2. The formation of N-Mn bonds via the coordination of amine groups of poly(allylamine hydrochloride) to the surface Mn sites of MnO 2 electrodes effectively stabilized the Mn 3+ species, resulting in an ∼500-mV negative shift of the onset potential for the O 2 evolution reaction at neutral pH. © 2012 American Chemical Society.

Kobayashi M.,Aoyama Gakuin University | Abe J.,Aoyama Gakuin University | Abe J.,Japan Science and Technology Agency
Journal of the American Chemical Society | Year: 2012

Graphite has been known as a typical diamagnetic material and can be levitated in the strong magnetic field. Here we show that the magnetically levitating pyrolytic graphite can be moved in the arbitrary place by simple photoirradiation. It is notable that the optical motion control system described in this paper requires only NdFeB permanent magnets and light source. The optical movement is driven by photothermally induced changes in the magnetic susceptibility of the graphite. Moreover, we demonstrate that light energy can be converted into rotational kinetic energy by means of the photothermal property. We find that the levitating graphite disk rotates at over 200 rpm under the sunlight, making it possible to develop a new class of light energy conversion system. © 2012 American Chemical Society.

Abe M.,Hiroshima University | Abe M.,Japan Institute for Molecular Science | Abe M.,Japan Science and Technology Agency
Chemical Reviews | Year: 2013

Recent development in diradical chemistry are summarized in detail. Diradicals are long-known chemical species, but they continue to be fascinating molecules because of their inherently high reactivity and their potential molecular functions, which are mainly derived from their small HOMO-LUMO energy gaps. Kinetic stabilization and thermodynamic stabilization have made it possible to isolate diradical species. The terminology of singlet and triplet states in diradicals is derived from the number of energy level in diradicals under an external magnetic field. The triplet state is the ground-state spin multiplicity for diradicals in which a large overlap integral exists between the two energetically degenerate molecular orbitals that are occupied by two electrons. Localized diradicals are key intermediates in processes involving the homolytic bond-cleavage and -formation reactions of cyclic compounds.

Masuda S.,Tokyo Institute of Technology | Masuda S.,Japan Science and Technology Agency
Plant and Cell Physiology | Year: 2013

BLUF (sensor of blue light using FAD) domain-containing proteins are one of three types of flavin-binding, blue-light-sensing proteins found in many bacteria and some algae. The other types of blue-light-sensing proteins are the cryptochromes and the light, oxygen, voltage (LOV) domain-containing proteins. BLUF proteins control a wide variety of light-dependent physiological activities including photosystem synthesis, biofilm formation and the photoavoidance response. The BLUF domain photochemical reaction is unique in that only small chromophore structural changes are involved in the light activation process, because the rigid flavin moiety is involved, rather than an isomerizable chromophore (e.g. phytochromobilin in phytochromes and retinal in rhodopsins). Recent spectroscopic, biochemical and structural studies have begun to elucidate how BLUF domains transmit the light-induced signal and identify related, subsequent changes in the domain structures. Herein, I review progress made to date concerning the physiological functions and the phototransduction mechanism of BLUF proteins. © 2012 The Author 2012. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved.

Perez Koldenkova V.,Osaka University | Nagai T.,Osaka University | Nagai T.,Japan Science and Technology Agency
Biochimica et Biophysica Acta - Molecular Cell Research | Year: 2013

Genetically encoded calcium ion (Ca2+) indicators have become very useful and widely used tools for Ca2+ imaging, not only in cellular models, but also in living organisms. However, the in vivo and in situ characterization of these indicators is tedious and time consuming, and it does not provide information regarding the suitability of an indicator for particular experimental environments. Thus, initial in vitro evaluation of these tools is typically performed to determine their properties. In this review, we examined the properties of dynamic range, affinity, selectivity, and kinetics for Ca2+ indicators. Commonly used strategies for evaluating these properties are presented. This article is part of a Special Issue entitled: 12th European Symposium on Calcium. © 2013 Elsevier B.V.

Shibu E.S.,Japan National Institute of Advanced Industrial Science and Technology | Hamada M.,Japan National Institute of Advanced Industrial Science and Technology | Murase N.,Japan National Institute of Advanced Industrial Science and Technology | Biju V.,Japan National Institute of Advanced Industrial Science and Technology | Biju V.,Japan Science and Technology Agency
Journal of Photochemistry and Photobiology C: Photochemistry Reviews | Year: 2013

Nanomaterials with well-defined size, shape, composition, and surface functionalities offer multimodal and multifunctional platforms for various bioanalytical, bioimaging, and therapeutic applications. In this review, we focus on the different theranostic formulations of nanomaterials based on gold, silver, silica, semiconductor quantum dots, upconversion lanthanides, oxide magnets, polymers, liposomes, carbon nanotubes, graphene and carbon nanohorns, and their applications in photothermal and photodynamic therapy of cancer. © 2012 Elsevier B.V.

Ueno K.,Hokkaido University | Ueno K.,Japan Science and Technology Agency | Misawa H.,Hokkaido University
Journal of Photochemistry and Photobiology C: Photochemistry Reviews | Year: 2013

The electromagnetic field enhancement effect based on the excitation of localized surface plasmon resonance was developed for various photochemical reaction systems, such as nano-lithography, photovoltaic cells, photocatalysis, and water splitting systems. As with most points characteristic of these surface plasmon-enhanced photochemical reactions, spatially selective photochemical reactions can be induced and photons can be efficiently utilized, a concept that could contribute to the development of green nanotechnology. Electromagnetic field enhancement effects based on plasmon excitation have contributed not only to physical processes, such as excitation efficiency, but also to chemical processes, such as photo-induced electron transfer reactions. This review article describes advanced studies on a wide variety of surface plasmon-enhanced photochemical reactions. © 2013 Elsevier B.V.

Oda Y.,University of Tokyo | Oda Y.,Japan Science and Technology Agency | Fukuda H.,University of Tokyo
Current Opinion in Plant Biology | Year: 2013

Proper patterning of cellulosic cell walls is critical for cell shaping and differentiation of plant cells. Cortical microtubule arrays regulate the deposition patterns of cellulose microfibrils by controlling the targeting and trajectory of cellulose synthase complexes. Although some microtubule-associated proteins (MAPs) regulate the arrangement of cortical microtubules, knowledge about the overall mechanism governing the spacing of cortical microtubules is still limited. Recent studies reveal that ROP GTPases and MAPs spatially regulate the assembly and disassembly of cortical microtubules in developing xylem cells, in which localized secondary cell walls are deposited. Here, we review recent insights into the regulation of xylem cell wall patterning by cortical microtubules, ROP GTPases, and MAPs. © 2013 Elsevier Ltd.

Hatakeyama H.,Tohoku University | Kanzaki M.,Tohoku University | Kanzaki M.,Japan Science and Technology Agency
Traffic | Year: 2011

Development of a 'static retention' property of GLUT4, the insulin-responsive glucose transporter, has emerged as being essential for achieving its maximal insulin-induced surface exposure. Herein, employing quantum-dot-based nanometrology of intracellular GLUT4 behavior, we reveal the molecular basis of its systematization endowed upon adipogenic differentiation of 3T3L1 cells. Specifically, (i) the endosomes-to-trans-Golgi network (TGN) retrieval system specialized for GLUT4 develops in response to sortilin expression, which requires an intricately balanced interplay among retromers, golgin-97 and syntaxin-6, the housekeeping vesicle trafficking machinery. (ii) The Golgin-97-localizing subdomain of the differentiated TGN apparently serves as an intermediate transit route by which GLUT4 can further proceed to the stationary GLUT4 storage compartment. (iii) AS160/Tbc1d4 then renders the 'static retention' property insulin responsive, i.e. insulin liberates GLUT4 from the static state only in the presence of functional AS160/Tbc1d4. (iv) Moreover, sortilin malfunction and the resulting GLUT4 sorting defects along with retarded TGN function might be etiologically related to insulin resistance. Together, these observations provide a conceptual framework for understanding maturation/retardation of the insulin-responsive GLUT4 trafficking system that relies on the specialized subdomain of differentiated TGN. © 2011 John Wiley & Sons A/S.

Wang J.,Yamagata University | Higashihara T.,Yamagata University | Higashihara T.,Japan Science and Technology Agency
Polymer Chemistry | Year: 2013

Electron donor-acceptor triblock and diblock copolymers have attracted considerable interest due to their potential applications in all-polymer solar cells as single-active components or surfactants. However, the number of donor-acceptor block copolymers has lagged behind that of the rod-coil and rod-rod block copolymers due to their synthetic difficulties. This minireview highlights the recent advances in the synthetic strategies for the all-conjugated donor-acceptor block copolymers and their application in all-polymer solar cells. This journal is © The Royal Society of Chemistry.

Shigematsu A.,Kyoto University | Shigematsu A.,Kyushu University | Yamada T.,Kyoto University | Kitagawa H.,Kyoto University | And 2 more authors.
Journal of the American Chemical Society | Year: 2011

The proton conductivities of the porous coordination polymers M(OH)(bdc-R) [H2bdc = 1,4-benzenedicarboxylic acid; M = Al, Fe; R = H, NH 2, OH, (COOH)2] were investigated under humid conditions. Good correlations among pKa, proton conductivity, and activation energy were observed. Fe(OH)(bdc-(COOH)2), having carboxy group and the lowest pKa, showed the highest proton conductivity and the lowest activation energy in this system. This is the first example in which proton conductivity has been widely controlled by substitution of ligand functional groups in an isostructural series. © 2011 American Chemical Society.

Harada A.,Osaka University | Harada A.,Japan Science and Technology Agency | Kobayashi R.,Osaka University | Takashima Y.,Osaka University | And 2 more authors.
Nature Chemistry | Year: 2011

Molecular recognition plays an important role in nature, with perhaps the best known example being the complementarity exhibited by pairs of nucleobases in DNA. Studies of self-assembling and self-organizing systems based on molecular recognition are often performed at the molecular level, however, and any macroscopic implications of these processes are usually far removed from the specific molecular interactions. Here, we demonstrate that well-defined molecular-recognition events can be used to direct the assembly of macroscopic objects into larger aggregated structures. Acrylamide-based gels functionalized with either host (cyclodextrin) rings or small hydrocarbon-group guest moieties were synthesized. Pieces of host and guest gels are shown to adhere to one another through the mutual molecular recognition of the cyclodextrins and hydrocarbon groups on their surfaces. By changing the size and shape of the host and guest units, different gels can be selectively assembled and sorted into distinct macroscopic structures that are on the order of millimetres to centimetres in size. © 2011 Macmillan Publishers Limited. All rights reserved.

Hatakeyama T.,Kyoto University | Hatakeyama T.,Japan Science and Technology Agency | Hashimoto S.,Kyoto University | Seki S.,Osaka University | Nakamura M.,Kyoto University
Journal of the American Chemical Society | Year: 2011

A tandem intramolecular electrophilic arene borylation reaction has been developed for the synthesis of BN-fused polycyclic aromatic compounds such as 4baza-12b-boradibenzo[g,p]chrysene (A) and 8b,11b-diaza-19b,22b- diborahexabenzo[a,c,fg,j,l,op]tetracene. These compounds adopt a twisted conformation, which results in a tight and offset face-to-face stacking array in the solid state. Timeresolved microwave conductivity measurements prove that the intrinsic hole mobility of A is comparable to that of rubrene, one of the most commonly used organic semiconductors, indicating that BN-substituted PAHs are potential candidates for organic electronic materials. © 2011 American Chemical Society.

Saijo H.,Osaka University | Ohashi M.,Osaka University | Ogoshi S.,Osaka University | Ogoshi S.,Japan Science and Technology Agency
Journal of the American Chemical Society | Year: 2014

We report a copper-mediated synthesis of a variety of 1,2-difunctionalized-1,1,2,2-tetrafluoroethylene derivatives via the carbocupration of tetrafluoroethylene. The key synthetic intermediates, 2-aryl-1,1,2,2-tetrafluoroethylcopper complexes, can be easily prepared, stored, and used as fluoroalkylation reagents. The molecular structure was unambiguously determined by X-ray crystallography and NMR analysis. We applied this method to the short-step synthesis of a liquid-crystalline compound bearing a tetrafluoroethylene-bridging structure. © 2014 American Chemical Society.

Ohno T.,University of Tokyo | Bai L.,University of Tokyo | Hisatomi T.,University of Tokyo | Maeda K.,University of Tokyo | And 2 more authors.
Journal of the American Chemical Society | Year: 2012

Overall water splitting using GaN:ZnO solid solution photocatalyst modified with Rh 2-yCr yO 3 nanoparticles as H 2 evolution cocatalysts under visible light (400 < < 500 nm) was examined with respect to long-term durability and regeneration of photocatalytic activity. The rate of visible light water splitting remained unchanged for 3 months (2160 h), producing H 2 and O 2 continuously at a stoichiometric amount. After 6 months of operation, a 50% loss of the initial activity occurred. Regeneration treatment of deactivated catalysts was attempted by reloading the Rh 2-yCr yO 3 cocatalyst. The degree of activity regeneration depended on the reloading amount. Up to 80% of the initial activity for H 2 evolution could be recovered under optimal treatment conditions. It was also found that deactivation of GaN:ZnO was suppressed to some extent by prior coloading of an O 2 evolution cocatalyst, which helped to suppress oxidative decomposition of GaN:ZnO by valence band holes, thereby improving the durability. © 2012 American Chemical Society.

Shima K.,Aoyama Gakuin University | Mutoh K.,Aoyama Gakuin University | Kobayashi Y.,Aoyama Gakuin University | Abe J.,Aoyama Gakuin University | Abe J.,Japan Science and Technology Agency
Journal of the American Chemical Society | Year: 2014

The widely tunable optical properties and the visible sensitivity have been required for fast photochromic molecules whose coloration-decoloration cycle completes in μs to ms time scale not only for practical applications such as full-color holographic displays but also for fundamental researches in biochemistry. However, the so far developed [2.2]paracyclophane-bridged imidazole dimers, which are one of the best candidates for fast photochromic molecules, have their weaknesses for these requirements. Herein, we overcome the issues with sustaining fast photochromism and high durability by flipping the two imidazole rings (the head-to-tail and tail-to-tail forms). The alteration in the relative configuration of the imidazole rings suppresses the broad absorption band resulting from the radical-radical interaction. The substitution to the 2-position of the imidazole ring of the tail-to-tail form gives the drastic changes in the steady-state and the transient absorption spectra. The pyrene-substituted tail-to-tail form demonstrates that the transient absorption spectrum is featured by the inherent spectrum of the imidazolyl radical. This molecular framework is easy to functionalize fast photochromic molecules such as sensitizations to the red light, chirality, and biological tagging, and therefore it is versatile for various fast photochromic applications. © 2014 American Chemical Society.

Nagata Y.,Kyoto University | Takagi K.,Kyoto University | Suginome M.,Kyoto University | Suginome M.,Japan Science and Technology Agency
Journal of the American Chemical Society | Year: 2014

Poly(quinoxaline-2,3-diyl)s bearing (S)-2-methylbutyl, n-butyl, and 8-chlorooctyl groups as side chains were synthesized to fabricate dry solid polymer thin films. These films exhibited selective reflection of right-handed circular polarized light (CPL) in the visible region after annealing in CHCl3 vapor at room temperature. The handedness of reflected CPL was inverted to the left after annealing in 1,2-dichloroethane vapor. It was also found that the color of a particular single film along with the handedness of reflected CPL were fully tuned reversibly, upon exposure of the film to the vapor of various mixtures of chloroform and 1,2-dichloroethane in different ratios. © 2014 American Chemical Society.

Wakioka M.,Kyoto University | Ichihara N.,Kyoto University | Kitano Y.,Kyoto University | Ozawa F.,Kyoto University | Ozawa F.,Japan Science and Technology Agency
Macromolecules | Year: 2014

π-Conjugated polymers with a donor-acceptor (DA) combination of repeating units possess a narrow HOMO-LUMO gap, thus resulting in a high device performance in solar cells. This paper reports an improved catalytic system for the synthesis of DA polymers containing 5-(2-hexyldecyl)-5H-thieno[3,4-c] pyrrole-4,6-dione-1,3-diyl (TPD) group as the acceptor unit via palladium-catalyzed direct arylation polymerization. Although a related study has been reported (Angew. Chem. Int. Ed. 2012, 51, 2068), we attempted to reduce the catalyst loading because the palladium residue in π-conjugated polymers has been known to produce a detrimental effect on device performance. As a result, the amount of palladium could be reduced to 1/8 by using PdCl 2(MeCN)2 and P(C6H4-o-OMe) 3 (L1) as catalyst precursors. The polymerization smoothly proceeds at 100 C in THF in the presence of pivalic acid and Cs2CO3 to afford TPD-based DA polymers 3a-3d containing the following donor units in almost quantitative yields: 4,4′-dioctyl-2,2′-bithiophene-5, 5′-diyl (3a, Mn = 36800, Mw/Mn = 2.20), 4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl (3b, Mn = 31100, Mw/Mn = 2.44), 3,4-(2,2′- dioctylpropylenedioxy)thiophene-2,5-diyl (3c, Mn = 68200, M w/Mn = 3.04), and 2,5-bis(2-ethylhexyloxy)-1,4-phenylene (3d, Mn = 65500, Mw/Mn = 2.21). A detailed analysis of the structure of 3a is reported. © 2014 American Chemical Society.

Kinoshita T.,Yokohama City University | Seki M.,Yokohama City University | Seki M.,RIKEN | Seki M.,Japan Science and Technology Agency
Plant and Cell Physiology | Year: 2014

In contrast to the majority of animal species, plants are sessile organisms and are, therefore, constantly challenged by environmental perturbations. Over the past few decades, our knowledge of how plants perceive environmental stimuli has increased considerably, e.g. the mechanisms for transducing environmental stress stimuli into cellular signaling cascades and gene transcription networks. In addition, it has recently been shown that plants can remember past environmental events and can use these memories to aid responses when these events recur. In this mini review, we focus on recent progress in determination of the epigenetic mechanisms used by plants under various environmental stresses. Epigenetic mechanisms are now known to play a vital role in the control of gene expression through small RNAs, histone modifications and DNA methylation. These are inherited through mitotic cell divisions and, in some cases, can be transmitted to the next generation. They therefore offer a possible mechanism for stress memories in plants. Recent studies have yielded evidence indicating that epigenetic mechanisms are indeed essential for stress memories and adaptation in plants. © © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.

Higuchi M.,Japan National Institute of Materials Science | Higuchi M.,Japan Science and Technology Agency
Journal of Materials Chemistry C | Year: 2014

Metallo-supramolecular polymers, which were synthesized via the 1:1 complexation of metal ions with ditopic organic ligands, showed unique electro- and photo-chemical properties based on the metal-ligand or metal-metal interactions. Fe(ii)-, Ru(ii)- and Cu(ii)-based metallo-supramolecular polymer films exhibited reversible electrochromic behaviour and electrochromic display devices were successfully fabricated. A polymer containing both Fe(ii) and Ru(ii) ions exhibited multi-colour electrochromic properties. Ionic conductivity of a Ni(ii)-based polymer film was significantly enhanced with increasing humidity, and real-time humidity sensing was realized by utilizing the polymer film. A Eu(iii)-based polymer showed vapoluminescence. Reversible switching of emission was achieved in the polymer with Fe(ii) and Eu(iii) ions introduced in an alternating manner. This journal is © the Partner Organisations 2014.

Zhang H.,Wuhan University of Science and Technology | Toshima N.,Tokyo University of Science, Yamaguchi | Toshima N.,Japan Science and Technology Agency
Catalysis Science and Technology | Year: 2013

Clean syntheses, based on the use of natural renewable reagents, in water solution under mild conditions, are highly desirable processes and often the catalytic step is a key factor for the successful application. Gold (Au) and Au-containing bimetallic and trimetallic nanoparticles (BNPs and TNPs) have been extensively investigated as the promising catalysts for the clean syntheses of gluconic acid, which is an important intermediate in the field of food industry and pharmaceutical applications, by glucose oxidation using atmospheric oxygen or hydrogen peroxide as an oxidant. With significant research efforts, a lot of new efficient catalytic systems, based on the peculiar properties of nanometric Au NPs, have been developed for aerobic glucose oxidation. In this minireview, we provide an overview of the recent development of Au-containing BNPs and TNPs for the improved catalytic performance toward glucose oxidation. This journal is © The Royal Society of Chemistry 2013.

Maeda K.,Tokyo Institute of Technology | Maeda K.,Japan Science and Technology Agency
Physical Chemistry Chemical Physics | Year: 2013

Water splitting to form H2 and O2 using semiconductor photocatalysts under sunlight is a possible means of clean energy production from renewable resources. (Oxy)nitrides are regarded as suitable candidates for the application, because of their suitable band edge positions, small band gaps (<3 eV), and stability under irradiation. Since early reports published in 2002 by Domen et al., it has been demonstrated that several (oxy)nitrides are active photocatalysts capable of reducing and oxidizing water in the presence of suitable electron donors and acceptors, respectively, under visible light (λ > 400 nm). Some have achieved direct water splitting into H 2 and O2 with good reproducibility. (Oxy)nitrides are also attractive as water-splitting photoelectrodes, and highly efficient photoelectrochemical water splitting has been accomplished using tantalum-based (oxy)nitrides under visible light with good stability. However, there still remain a lot of challenges that have to be addressed in this research field. This perspective highlights recent progress in the development of (oxy)nitride materials for application in photocatalytic and photoelectrochemical water splitting made by the author and his colleagues, especially in the last 5 years. © 2013 the Owner Societies.

Hori Y.,Osaka University | Hori Y.,Japan Science and Technology Agency | Kikuchi K.,Osaka University
Current Opinion in Chemical Biology | Year: 2013

Protein labeling by using a protein tag and its specific fluorescent probe is increasingly becoming a useful technique for the real-time imaging of proteins in living cells. Recently, fluorogenic probes for protein labeling were developed. When using these probes, a washing step is not required for the removal of free probes from the cells, thus, allowing rapid detection of proteins in living cells with high signal-to-noise ratio. Various chemical principles have been applied in the designing of probes to include a turn-on fluorescence switch that is activated by the protein labeling reaction. In this review, we describe about the design strategy of the probes and the advances in fluorogenic protein labeling systems. © 2013 Elsevier Ltd.

Yorimitsu H.,Kyoto University | Yorimitsu H.,Japan Science and Technology Agency
Beilstein Journal of Organic Chemistry | Year: 2013

Organophosphorus compounds are important in organic chemistry. This review article covers emerging, powerful synthetic approaches to organophosphorus compounds by homolytic substitution at phosphorus with a carbon-centered radical. Phosphination reagents include diphosphines, chalcogenophosphines and stannylphosphines, which bear a weak P-heteroatom bond for homolysis. This article deals with two transformations, radical phosphination by addition across unsaturated C-C bonds and substitution of organic halides. © 2013 Yorimitsu; licensee Beilstein-Institut.

Ida S.,Kyushu University | Ida S.,Japan Science and Technology Agency | Takashiba A.,Kyushu University | Koga S.,Kyushu University | And 2 more authors.
Journal of the American Chemical Society | Year: 2014

The creation of p-n junction structure in photocatalysts is a smart approach to improve the photocatalytic activity, as p-n junctions can potentially act to suppress the recombination reaction. Understanding the surface conditions of the junction parts is one of the biggest challenges in the development of photocatalyst surface chemistry. Here, we show a relationship between the photocatalytic activity and potential gradient of the junction surface prepared from two-dimensional crystals of p-type NiO and n-type calcium niobate (CNO). The ultrathin (ca. 2 nm) junction structure and the surface potential were analyzed using low energy ion scattering spectroscopy and Kelvin probe force microscopy. The photocatalytic H2 production rate for the n-p (CNO/NiO) junction surface was higher than those for p-n (NiO/CNO) junction, p, and n surfaces. The surface potential of the CNO/NiO junction part (surface: CNO) was lower than that of the CNO crystals in the same CNO crystal surface. These potential gradients result in specially separated reaction sites, which suppress the recombination reaction in the CNO nanosheet. Photo-oxidation and photoreduction sites in the junction structure were confirmed using the photodeposition reaction of MnOx and Ag. © 2014 American Chemical Society.

Hashimoto K.,Hiroshima University | Hashimoto K.,Japan Science and Technology Agency | Kano M.,University of Tokyo
Cellular and Molecular Life Sciences | Year: 2013

Neural circuits in neonatal animals contain numerous redundant synapses that are functionally immature. During the postnatal period, unnecessary synapses are eliminated while functionally important synapses become stronger and mature. The climbing fiber (CF) to the Purkinje cell (PC) synapse is a representative model for the analysis of postnatal refinement of neuronal circuits in the central nervous system. PCs are initially innervated by multiple CFs with similar strengths around postnatal day 3 (P3). Only a single CF is selectively strengthened during P3-P7 (functional differentiation), and the strengthened CF undergoes translocation from soma to dendrites of PCs from P9 on (dendritic translocation). Following the functional differentiation, supernumerary CF synapses on the soma are eliminated, which proceeds in two distinct phases: the early phase from P7 to around P11 and the late phase from around P12 to P17. Here, we review our current understanding of cellular and molecular mechanisms of CF synapse elimination in the developing cerebellum. © 2013 The Author(s).

Wakano J.Y.,Meiji University | Wakano J.Y.,Japan Science and Technology Agency | Iwasa Y.,Kyushu University
Genetics | Year: 2013

Adaptive dynamics formalism demonstrates that, in a constant environment, a continuous trait may first converge to a singular point followed by spontaneous transition from a unimodal trait distribution into a bimodal one, which is called "evolutionary branching." Most previous analyses of evolutionary branching have been conducted in an infinitely large population. Here, we study the effect of stochasticity caused by the finiteness of the population size on evolutionary branching. By analyzing the dynamics of trait variance, we obtain the condition for evolutionary branching as the one under which trait variance explodes. Genetic drift reduces the trait variance and causes stochastic fluctuation. In a very small population, evolutionary branching does not occur. In larger populations, evolutionary branching may occur, but it occurs in two different manners: in deterministic branching, branching occurs quickly when the population reaches the singular point, while in stochastic branching, the population stays at singularity for a period before branching out. The conditions for these cases and the mean branching-out times are calculated in terms of population size, mutational effects, and selection intensity and are confirmed by direct computer simulations of the individual-based model. © 2013 by the Genetics Society of America.

Seino S.,Kobe University | Seino S.,Japan Science and Technology Agency
Diabetologia | Year: 2012

Clarification of the molecular mechanisms of insulin secretion is crucial for understanding the pathogenesis and pathophysiology of diabetes and for development of novel therapeutic strategies for the disease. Insulin secretion is regulated by various intracellular signals generated by nutrients and hormonal and neural inputs. In addition, a variety of glucose-lowering drugs including sulfonylureas, glinide-derivatives, and incretin-related drugs such as dipeptidyl peptidase IV (DPP-4) inhibitors and glucagon-like peptide 1 (GLP-1) receptor agonists are used for glycaemic control by targeting beta cell signalling for improved insulin secretion. There has been a remarkable increase in our understanding of the basis of beta cell signalling over the past two decades following the application of molecular biology, gene technology, electrophysiology and bioimaging to beta cell research. This review discusses cell signalling in insulin secretion, focusing on the molecular targets of ATP, cAMP and sulfonylurea, an essential metabolic signal in glucose-induced insulin secretion (GIIS), a critical signal in the potentiation of GIIS, and the commonly used glucoselowering drug, respectively © Springer-Verlag 2012.

Takeuchi T.,Kochi Medical School | Adachi Y.,Hokkaido University | Nagayama T.,Japan Science and Technology Agency
Carcinogenesis | Year: 2012

Using the PCR-based subtractive messenger RNA hybridization assay described in this paper, we isolated a hitherto uncharacterized gene, transmembrane protein 207 (TMEM207), which was selectively expressed in collagen gel-invading cultured signet-ring cell carcinoma KATO-III cells. TMEM207 has a C-terminal proline-rich PPxY motif, which binds to the WW domain-containing oxidoreductase, WWOX. Enforced expression of TMEM207 significantly increased Matrigel invasion activity of KATO-III cells in vitro without affecting cell growth. In contrast, expression of TMEM207 with mutations in the PPxY motif did not significantly increase Matrigel invasion activity of KATO-III cells. Immunohistochemical staining showed that TMEM207 was strongly expressed in 7 of 30 gastric signet-ring cell carcinoma tissue specimens. Notably, TMEM207 expression was associated with the depth of cancer invasion and the presence of lymph node metastasis. The results of co-immunoprecipitation followed by western immunoblotting showed that TMEM207 is bound to WWOX in a PPxY motif-dependent manner. Small interfering RNA-mediated downregulation of WWOX also significantly increased Matrigel invasion activity of KATO-III cells. Notably, exogenous expression of TMEM207 impaired the WWOX-mediated repression of Matrigel invasion activity of another cultured signet-ring cell carcinoma cell line, NUGC-4 cells. Recent studies have highlighted the fact that WWOX acts as a tumor suppressor factor in various malignant tumors, including gastric cancer. On the basis of these findings and the results of the present study, we think that overexpression of TMEM207 may facilitate invasive activity and metastasis of gastric signet-ring cell carcinoma, which possibly occur through binding to WWOX and attenuation of its function. © The Author 2012. Published by Oxford University Press. All rights reserved.

Siomi M.C.,Keio University | Siomi M.C.,Japan Science and Technology Agency | Mannen T.,Keio University | Siomi H.,Keio University
Genes and Development | Year: 2010

PIWI (F-element-induced wimpy testis) proteins are a subset of the Argonaute proteins and are expressed predominantly in the germlines of a variety of organisms, including Drosophila and mammals. FIWI proteins associate specifically with FIWI-interacting RNAs (piRNAs), small RNAs that are also expressed predominantly in germlines, and silence transposable DNA elements and other genes showing complementarities to the sequences of associated piRNAs. This mechanism helps to maintain the integrity of the genome and the development of gametes. PIWI proteins have been shown recently to contain symmetrical dimethyl arginines (sDMAs), and this modification is mediated by the methyltransferase PRMT5 (also known as Dart5 or Capsuleen). It was then demonstrated that multiple members of the Tudor (Tud) family of proteins, which are necessary for gametogenesis in both flies and mice, associate with FIWI proteins specifically through sDMAs in various but particular combinations. Although Tud domains in Tud family members are known to be sDMA-binding modules, involvement of the Tudor family at the molecular level in the piRNA pathway has only recently come into focus. © 2010 by Cold Spring Harbor Laboratory Press.

Imahori H.,Kyoto University | Umeyama T.,Kyoto University | Umeyama T.,Japan Science and Technology Agency | Kurotobi K.,Kyoto University | Takano Y.,Kyoto University
Chemical Communications | Year: 2012

Large π-conjugated compounds are promising building blocks for organic thin-film electronics such as organic light-emitting diodes, organic field-effect transistors, and organic photovoltaics. Utilization of porphyrins and phthalocyanines for this purpose is highly fascinating because of their excellent electric, photophysical, and electrochemical properties as well as intense self-assembling abilities arising from π-π stacking interactions. This paper focuses on fundamental aspects of self-assembled structures that have been obtained from porphyrin and phthalocyanine building blocks and more complex composites for photoinduced charge separation and charge transport toward the potential applications to organic thin-film electronics. © 2012 The Royal Society of Chemistry.

Maeda K.,Tokyo Institute of Technology | Maeda K.,Japan Science and Technology Agency
ACS Applied Materials and Interfaces | Year: 2014

Rhodium-doped barium titanate (BaTiO3:Rh) powder was prepared by the polymerized complex (PC) method, and the photocatalytic activity for H 2 evolution from water was examined. BaTiO3 is a wide-gap n-type semiconductor having a band gap of 3.0 eV. Doping Rh species into the lattice of BaTiO3 resulted in the formation of new absorption bands in visible light region. Upon visible light (λ > 420 nm), BaTiO 3:Rh modified with nanoparticulate Pt as a water reduction promoter was capable of producing H2 from water containing an electron donor such as methanol and iodide. The best material prepared by the PC method exhibited higher activity than that made by a conventional solid-state reaction method. Visible-light-driven Z-scheme water splitting was also accomplished using Pt/BaTiO3:Rh as a building block for H2 evolution in combination with PtOx-loaded WO3 as an O2 evolution photocatalyst in the presence of an IO3 -/I - shuttle redox mediator. Photoelectrochemical analysis indicated that a porous BaTiO3:Rh electrode exhibited cathodic photoresponse due to water reduction in a neutral aqueous Na2SO4 solution upon visible light. © 2014 American Chemical Society.

Hatano M.,Nagoya University | Ishihara K.,Nagoya University | Ishihara K.,Japan Science and Technology Agency
Chemical Communications | Year: 2012

The potential of supramolecular catalysts to realize anomalous regio- and/or stereoselectivity in organic synthesis is highly attractive. To date, there have been a few examples of non-polymeric and non-covalent chiral supramolecular catalysts that induce practical enantioselectivity. In this regard, a metal-organic framework (MOF) may be one of the most important techniques for constructing conformationally rigid supramolecular catalysts. However, it is not easy to use the MOF technique to fine-tune a much more precise cage in catalysts for anomalous purposes. To establish high catalytic activity with anomalous regio- and/or stereoselectivity, in principle, an artificial cage should be conformationally flexible, like an active pocket in an enzyme with an induced-fit function. In this feature article, we focus on the anomalous endo/exo-selective Diels-Alder reaction, and overview the development of the successive catalysts including our recent highly active, conformationally flexible, and chiral supramolecular catalysts. The evolution from 'ready-made' single-molecule catalysts to 'tailor-made' supramolecular catalysts could offer not only high enantioselectivity but also high anomalous endo/exo-selectivities due to substrate-specific characteristics, as with enzymes. © The Royal Society of Chemistry 2012.

Yamasue H.,University of Tokyo | Yamasue H.,Japan Science and Technology Agency
Brain and Development | Year: 2013

Difficulties in appropriate social and communicative behaviors are the most prevalent and core symptoms of autism spectrum disorders (ASDs). Although recent intensive research has focused on the neurobiological background of these difficulties, many aspects of them were not yet elucidated. Recent studies have employed multimodal magnetic resonance imaging (MRI) indices as intermediate phenotypes of this behavioral phenotype to link candidate genes with the autistic social difficulty. As MRI indices, functional MRI (fMRI), structural MRI, and MR-spectroscopy have been examined in subjects with autism spectrum disorders. As candidate genes, this mini-review has much interest in oxytocin-receptor genes (OXTR), since recent studies have repeatedly reported their associations with normal variations in social cognition and behavior as well as with their extremes, autistic social dysfunction. Through previous increasing studies, medial prefrontal cortex, hypothalamus and amygdala have repeatedly been revealed as neural correlates of autistic social behavior by MRI multimodalities and their relationship to OXTR. For further development of this research area, this mini-review integrates recent accumulating evidence about human behavioral and neural correlates of OXTR. © 2012 The Japanese Society of Child Neurology.

Liu X.,RIKEN | Takumi T.,RIKEN | Takumi T.,Japan Science and Technology Agency
Biochemical and Biophysical Research Communications | Year: 2014

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with a strong genetic component. The past decade has witnessed tremendous progress in the genetic studies of ASD. In this article, we review the accumulating literatures on the monogenic forms of ASD and chromosomal abnormalities associated with ASD, the genome-wide linkage and association studies, the copy number variation (CNV) and the next generation sequencing (NGS) studies. With more than hundreds of mutations being implicated, the convergent biological pathways are emerging and the genetic landscape of ASD becomes clearer. The genetic studies provide a solid basis for future translational study for better diagnoses, intervention and treatment of ASD. © 2014 Elsevier Inc. All rights reserved.

Chen S.X.,University of California at San Diego | Kim A.N.,University of California at San Diego | Peters A.J.,University of California at San Diego | Komiyama T.,University of California at San Diego | Komiyama T.,Japan Science and Technology Agency
Nature Neuroscience | Year: 2015

Motor skill learning induces long-lasting reorganization of dendritic spines, principal sites of excitatory synapses, in the motor cortex. However, mechanisms that regulate these excitatory synaptic changes remain poorly understood. Here, using in vivo two-photon imaging in awake mice, we found that learning-induced spine reorganization of layer (L) 2/3 excitatory neurons occurs in the distal branches of their apical dendrites in L1 but not in the perisomatic dendrites. This compartment-specific spine reorganization coincided with subtype-specific plasticity of local inhibitory circuits. Somatostatin-expressing inhibitory neurons (SOM-INs), which mainly inhibit distal dendrites of excitatory neurons, showed a decrease in axonal boutons immediately after the training began, whereas parvalbumin-expressing inhibitory neurons (PV-INs), which mainly inhibit perisomatic regions of excitatory neurons, exhibited a gradual increase in axonal boutons during training. Optogenetic enhancement and suppression of SOM-IN activity during training destabilized and hyperstabilized spines, respectively, and both manipulations impaired the learning of stereotyped movements. Our results identify SOM inhibition of distal dendrites as a key regulator of learning-related changes in excitatory synapses and the acquisition of motor skills. © 2015 Nature America, Inc. All rights reserved.

Inoue M.,Japan Science and Technology Agency
Nature Methods | Year: 2014

Fluorescent Ca2+ reporters are widely used as readouts of neuronal activities. Here we designed R-CaMP2, a high-affinity red genetically encoded calcium indicator (GECI) with a Hill coefficient near 1. Use of the calmodulin-binding sequence of CaMKK-α and CaMKK-β in lieu of an M13 sequence resulted in threefold faster rise and decay times of Ca2+ transients than R-CaMP1.07. These features allowed resolving single action potentials (APs) and recording fast AP trains up to 20–40 Hz in cortical slices. Somatic and synaptic activities of a cortical neuronal ensemble in vivo were imaged with similar efficacy as with previously reported sensitive green GECIs. Combining green and red GECIs, we successfully achieved dual-color monitoring of neuronal activities of distinct cell types, both in the mouse cortex and in freely moving Caenorhabditis elegans. Dual imaging using R-CaMP2 and green GECIs provides a powerful means to interrogate orthogonal and hierarchical neuronal ensembles in vivo. © 2014 Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.

Sugimoto T.,University of Tokyo | Fukutani K.,University of Tokyo | Fukutani K.,Japan Science and Technology Agency
Nature Physics | Year: 2011

Molecules made of identical nuclei of non-zero spin exist in nuclear-spin modifications, and the interconversion of these spin isomers is often forbidden for isolated states1-3. The interconversion between the nuclear-spin modifications, however, is promoted by inhomogeneous magnetic fields, such as those present on the surfaces of magnetic materials4. Nuclear-spin conversion on diamagnetic and insulating solid substances, on the other hand, is generally considered improbable. Here we present the observation of nuclear-spin flips of H2 and D2 occurring on amorphous solid water surfaces with time constants of 370 -140 +340s and 1,220 -580 +2,980s, respectively. To explain these unexpected conversion processes, we propose a model of electric-field-induced nuclear-spin flips. In this model, giant and inhomogeneous electric fields present on the ice surface5 mix the electronic states of opposite parities by the Stark effect6, and significantly enhance the sping-orbit couplings between the electronic singlet-triplet spin states of the molecules. By virtue of these effects, the intramolecular hyperfine contact interaction induces the nuclear-spin conversion. This concept should have implications for controlling nuclear magnetization using external electric fields7. © 2011 Macmillan Publishers Limited. All rights reserved.

Tamasaku K.,RIKEN | Tamasaku K.,Japan Science and Technology Agency | Sawada K.,RIKEN | Nishibori E.,Nagoya University | Ishikawa T.,RIKEN
Nature Physics | Year: 2011

Scientists have continually tried to improve the spatial resolution of imaging ever since the invention of the optical microscope in around 1610 by Galileo. Recently, a spatial resolution near /10 was achieved in a near-field scheme by using surface plasmon polaritons. However, further improvement in this direction is hindered by the size of metallic nanostructures. Here we show that atom-scale resolution is achievable in the extreme-ultraviolet region by using X-ray parametric down-conversion, which detaches the achievable resolution from the wavelength of the probe light. We visualize three-dimensionally the local optical response of diamond at wavelengths between 103 and 206Å with a resolution as fine as 0.54Å. This corresponds to a resolution from /190 to /380, an order of magnitude better than ever achieved. Although the present study focuses on the relatively high-energy optical regions, our method could be extended into the visible region using advanced X-ray sources, and would open a new window into the optical properties of solids. © 2011 Macmillan Publishers Limited. All rights reserved.

Saito K.,Japan Science and Technology Agency | Ishikita H.,Osaka University
Biochimica et Biophysica Acta - Bioenergetics | Year: 2014

In the crystal structure of Photosystem II (PSII) analyzed at a resolution of 1.9 Å, most of the bond lengths between Mn and O atoms in the oxygen-evolving Mn4Ca cluster are 1.8-2.1 Å. On the other hand, the Mn1O5 bond in the Mn3CaO4 cubane region of the Mn4Ca cluster is significantly elongated to 2.6 Å. Using a quantum mechanical/molecular mechanical approach, we investigated factors that are responsible for distortion of the Mn3CaO4 cubane. Removal of Ca led to shortening the Mn1O5 bond by 0.2 Å; however, Mn1O5 remained significantly elongated, at > 2.5 Å. Conversely, removal of Mn4 significantly shortens the Mn1O5 distance by 0.5 Å to 2.2 Å, resulting in a more symmetric cubane shape. These results suggest that Mn4, not Ca, is predominantly responsible for distortion of the Mn3CaO 4 cubane. It was not the Ca component that was responsible for the existence of the two S2 conformers but two different Mn oxidation states (Mn1, Mn2, Mn3, M4) = (III, IV, IV, IV) and (IV, IV, IV, III); they were interconvertible by translocation of the O5 atom along the Mn1-O5-Mn4 axis. Depletion of Ca resulted in rearrangement of the H-bond network near TyrZ, which proceeds via a chloride ion (Cl-1 pathway). This may explain why Ca depletion inhibits the S2 to S3 transition, the same process that can also be inhibited by Cl- depletion. © 2013 Elsevier B.V.

Mishima E.,Kyoto University | Yamago S.,Kyoto University | Yamago S.,Japan Science and Technology Agency
Macromolecular Rapid Communications | Year: 2011

Alternating copolymers comprised of (meth)acrylates and vinyl ethers with controlled molecular weights and polydispersities were synthesized for the first time by living radical polymerization using organotellurium, stibine, and bismuthine chain transfer agents. Combining living alternating copolymerization and living radical or living cationic polymerization afforded hitherto unavailable block copolymers with controlled macromolecular structures. Alternating copolymers comprised of (meth)acrylates and vinyl ethers with controlled molecular weights and polydispersities were synthesized for the first time by LRP using organotellurium, stibine, and bismuthine chain transfer agents. Combining living alternating copolymerization and living radical or living cationic polymerization afforded hitherto unavailable block copolymers with controlled macromolecular structures.(Figure Presented) © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Matsui T.,Kyushu University | Ohki K.,Kyushu University | Ohki K.,Japan Science and Technology Agency
Frontiers in Neural Circuits | Year: 2013

Higher order visual areas that receive input from the primary visual cortex (V1) are specialized for the processing of distinct features of visual information. However, it is still incompletely understood how this functional specialization is acquired. Here we used in vivo two photon calcium imaging in the mouse visual cortex to investigate whether this functional distinction exists at as early as the level of projections from V1 to two higher order visual areas, AL and LM. Specifically, we examined whether sharpness of orientation and direction selectivity and optimal spatial and temporal frequency of projection neurons from V1 to higher order visual areas match with that of target areas. We found that the V1 input to higher order visual areas were indeed functionally distinct: AL preferentially received inputs from V1 that were more orientation and direction selective and tuned for lower spatial frequency compared to projection of V1 to LM, consistent with functional differences between AL and LM. The present findings suggest that selective projections from V1 to higher order visual areas initiates parallel processing of sensory information in the visual cortical network. © 2013 Matsui and Ohki.

Suetsugu S.,University of Tokyo | Suetsugu S.,Japan Science and Technology Agency
Journal of Biochemistry | Year: 2010

The plasma membrane, the outermost surface of eukaryotic cells, contains various substructures, such as protrusions or invaginations, which are associated with diverse functions, including endocytosis and cell migration. These structures of the plasma membrane can be considered as tubules or inverted tubules (protrusions) of the membrane. There are six modes of membrane curvature at the plasma membrane, which are classified by the positive or negative curvature and the location of the curvature (tip, neck or shaft of the tubules). The BAR domain superfamily proteins have structurally determined positive and negative curvatures of membrane contact at their BAR, F-BAR and I-BAR domains, which generate and maintain such curved membranes by binding to the membrane. Importantly, the SH3 domains of the BAR domain superfamily proteins bind to the actin regulatory WASP/WAVE proteins, and the BAR/F-BAR/I-BAR domain-SH3 unit could orient the actin filaments towards the membrane for each subcellular structure. These membrane tubulations are also considered to function in membrane fusion and fission. © 2010 The Authors.

Watanabe T.,Nara Institute of Science and Technology | Takahashi Y.,Nara Institute of Science and Technology | Takahashi Y.,Japan Science and Technology Agency
Current Opinion in Genetics and Development | Year: 2010

When different tissues successively emerge during development, they need to be morphologically segregated from each other. Morphological segregation of tissues is often accompanied by robust changes in cell shape, and these two events are precisely coordinated. We overview recent progress in understanding how such coordination is regulated at the cellular and molecular levels using vertebrate somitogenesis as a unique model. In the formation of the somitic gap and its concomitant cell epithelialization, Ephrin-Eph intercellular signals play a central role, with Ephrin transducing intracellular signals via suppression of Cdc42. These signals lead to the activation of integrin where the segment border of somites forms, which in turn induces the assembly of fibronectin, the final player for the coordination. Intimate coupling of tissue-shape and cell-shape changes is also relevant to tumor suppression. © 2010 Elsevier Ltd.

Hatano S.,Aoyama Gakuin University | Abe J.,Aoyama Gakuin University | Abe J.,Japan Science and Technology Agency
Physical Chemistry Chemical Physics | Year: 2012

2,4,5-Triphenylimidazole (lophine) is known as the first chemiluminescence substrate, and its oxidized derivative, the 2,4,5-triphenylimidazolyl radical, corresponds to the coloured species in the photochromic reaction of hexaarylbiimidazole (HABI). We report the first direct observation of the O 2 adduct of the imidazolyl radical that forms the end-on peroxide-bridged imidazole dimer. The ring-opening reaction of the peroxide-bridged imidazole dimer leading to the formation of an N-benzoylbenzamidine derivative supports the presence of the 4,5-epidioxide of lophine as a reaction intermediate of its chemiluminescence. © the Owner Societies 2012.

Shiogai J.,Tohoku University | Ito Y.,Tohoku University | Mitsuhashi T.,Tohoku University | Nojima T.,Tohoku University | And 2 more authors.
Nature Physics | Year: 2016

Among the recently discovered iron-based superconductors, ultrathin films of FeSe grown on SrTiO3 substrates have uniquely evolved into a high-transition-temperature (T c) superconducting material. The mechanisms for the high-T c superconductivity are under debate, with the superconducting gap mainly characterized with in situ analysis for FeSe films grown by molecular beam epitaxy. Here, we investigate the high-T c superconductivity in ultrathin FeSe using an alternative top-down electrochemical etching technique in a three-terminal transistor configuration. In addition to the high-temperature superconductivity in FeSe on SrTiO3, the electrochemically etched ultrathin FeSe transistor on MgO also exhibits superconductivity around 40 K, implying that the application of an electric field effectively contributes to the high-T c superconductivity in ultrathin FeSe regardless of substrate material. Moreover, the observable critical thickness for the high-T c superconductivity is expanded up to 10 unit cells under an applied electric field and the insulator-superconductor transition is electrostatically controlled. The present demonstration implies that the modification of charge imbalance of holes and electrons by the electric-field effect plays a crucial role in inducing high-T c superconductivity in FeSe-based electric double-layer transistors. © 2016 Macmillan Publishers Limited.

Suwa H.,University of Tokyo | Todo S.,University of Tokyo | Todo S.,Japan Science and Technology Agency
Physical Review Letters | Year: 2010

We present a specific algorithm that generally satisfies the balance condition without imposing the detailed balance in the Markov chain Montea Carlo. In our algorithm, the average rejection rate is minimized, and even reduced to zero in many relevant cases. The absence of the detailed balance also introduces a net stochastic flow in a configuration space, which further boosts up the convergence. We demonstrate that the autocorrelation time of the Potts model becomes more than 6 times shorter than that by the conventional Metropolis algorithm. Based on the same concept, a bounce-free worm algorithm for generic quantum spin models is formulated as well. © 2010 The American Physical Society.

Amano M.,Nagoya University | Nakayama M.,Max Planck Institute for Molecular Biomedicine | Kaibuchi K.,Nagoya University | Kaibuchi K.,Japan Science and Technology Agency
Cytoskeleton | Year: 2010

10.1002/cm.20472.absRho-associated kinase (Rho-kinase/ROCK/ROK) is an effector of the small GTPase Rho and belongs to the AGC family of kinases. Rho-kinase has pleiotropic functions including the regulation of cellular contraction, motility, morphology, polarity, cell division, and gene expression. Pharmacological analyses have revealed that Rho-kinase is involved in a wide range of diseases such as vasospasm, pulmonary hypertension, nerve injury, and glaucoma, and is therefore considered to be a potential therapeutic target. This review focuses on the structure, function, and modes of activation and action of Rho-kinase. © 2010 Wiley-Liss, Inc.

Iwasaki K.,Osaka University | Iwasaki K.,Japan Science and Technology Agency | Omura T.,Japan National Agricultural Research Center
Current Opinion in Structural Biology | Year: 2010

Visualizing the viral life cycle in the host challenges us to extend our understanding of the viral infection mechanism. Three-dimensional images obtained by advanced electron tomographic imaging techniques, if resolved to molecular resolution, are helpful for bridging the atomic structural information of proteins to cellular events. Characteristic large structures appear in virus-infected host cells through the life cycle of various viruses. These structures are likely to provide clues to understanding viral infection mechanisms, such as how viruses move in host cells, how they are assembled, how they egress and how they spread cell-to-cell. Here we review recent advances in the studies of the molecular architecture of virus machinery involved in the mechanism of virus infection using comprehensive electron tomographic imaging techniques. © 2010 Elsevier Ltd.

Suetsugu S.,University of Tokyo | Suetsugu S.,Japan Science and Technology Agency | Toyooka K.,RIKEN | Senju Y.,University of Tokyo
Seminars in Cell and Developmental Biology | Year: 2010

The Bin-Amphiphysin-Rvs167 (BAR) domain superfamily consists of proteins containing the BAR domain, the extended FCH (EFC)/FCH-BAR (F-BAR) domain, or the IRSp53-MIM homology domain (IMD)/inverse BAR (I-BAR) domain. These domains bind membranes through electrostatic interactions between the negative charges of the membranes and the positive charges on the structural surface of homo-dimeric BAR domain superfamily members. Some BAR superfamily members have membrane-penetrating insertion loops, which also contribute to the membrane binding by the proteins. The membrane-binding surface of each BAR domain superfamily member has its own unique curvature that governs or senses the curvature of the membrane for BAR-domain binding. The wide range of BAR-domain surface curvatures correlates with the various invaginations and protrusions of cells. Therefore, each BAR domain superfamily member may generate and recognize the curvature of the membrane of each subcellular structure, such as clathrin-coated pits or filopodia. The BAR domain superfamily proteins may regulate their own catalytic activity or that of their binding proteins, depending on the membrane curvature of their corresponding subcellular structures. © 2009 Elsevier Ltd. All rights reserved.

Otera H.,Kyushu University | Fujiki Y.,Kyushu University | Fujiki Y.,Japan Science and Technology Agency
Traffic | Year: 2012

Human catalase forms a 240-kDa tetrameric complex and degrades H2O2 in peroxisomes. Human catalase is targeted to peroxisomes by the interaction of its peroxisomal targeting signal type 1 (PTS1)-like KANL sequence with the cytosolic PTS1 receptor Pex5p. We show herein that human catalase tetramers are formed in the cytoplasm and that the expression of a PTS signal on each of the four subunits is not necessary for peroxisomal transport. We previously demonstrated that a Pex5p mutant defective in binding to Pex13p, designated Pex5p(Mut234), imports typical PTS1-type proteins but not catalase. This impaired catalase import is not rescued by replacing its C-terminal KANL sequence with a typical PTS1 sequence, SKL, indicating that the failure of catalase import in Mut234-expressing cells is not due to its weak PTS1. In contrast, several enzymatically inactive and monomeric mutants of catalase are efficiently imported in Mut234-expressing cells. Moreover, trimeric chloramphenicol acetyltransferase (CAT) harboring SKL is not imported in Pex5p(Mut234)-expressing cells, but CAT-SKL trimers are transported to peroxisomes in the wild-type cells. These findings suggest that the Pex5p-Pex13p interaction likely plays a pivotal role in the peroxisomal import of folded and oligomeric proteins. © 2012 John Wiley & Sons A/S.

Kiyomitsu T.,Nagoya University | Kiyomitsu T.,Japan Science and Technology Agency
Trends in Cell Biology | Year: 2015

Daughter cell size is tightly regulated during cell division. In animal cells, the position of the anaphase spindle specifies the cell cleavage site to dictate the relative size of the daughter cells. Although spindle orientation is regulated by dynein-dependent cortical pulling forces exerted on astral microtubules in many cell types, it was unclear how these forces are precisely regulated to center or displace the spindle. Recently, intrinsic signals derived from chromosomes or spindle poles have been demonstrated to regulate dynein-dependent pulling forces in symmetrically dividing cells. Unexpectedly, myosin-dependent contractile forces have also been shown to control spindle position by altering the cellular boundaries during anaphase. In this review, I discuss how dynein- and myosin-dependent forces are coordinately regulated to control daughter cell size. © 2014 Elsevier Ltd.

Matsunaga S.,University of Tokyo | Matsunaga S.,Japan Science and Technology Agency | Shibasaki M.,Institute of Microbial Chemistry
Synthesis (Germany) | Year: 2013

Multimetallic salen and related Schiff base complexes designed for cooperative asymmetric catalysis are introduced. First, studies to enhance the cooperative function of two distinct metal-salen units using covalently linked metal-salen complexes, supramolecular bimetallic salens as well as μ-oxo-bridged metal salens are described. Then, studies to design dinuclear Schiff base catalysts that exhibit unique intramolecular cooperative functions of two distinct metals are discussed in detail. © Georg Thieme Verlag Stuttgart · New York.

Nasua K.,Japan Science and Technology Agency
European Physical Journal B | Year: 2010

Photoinduced structural phase transition (PSPT)s are reviewed in connection with recent experimental results. There are two key concepts: the hidden multi-stability of the ground state, and the proliferations of optically excited states. Taking the ionic (I)-neutral (N) phase transition in an organic charge-transfer (CT) crystal TTF-CA, as an example, we, briefly look back the essence of its PSPT, in terms of the CT exciton and the N-domain proliferation. Next, we are concerned with the discovery of a new photoinduced phase with inter-layer σ-bonds in a graphite. We will see the mechanism of this nonequilibrium phase transition, in terms of the proliferation of photo-generated inter-layer CT excitations in the visible region. At the Franck-Condon state, the resultant electron-hole pair is quite unstable, being easily dissipated into the two-dimensional electronic continuum, as plus and minus free carriers. However, by a small probability, the electron and the hole are bound as an inter-layer CT exciton. This exciton self-localizes, contracting the inter-layer distance and buckling the six membered ring of graphite, only around it. Thus a tiny sp 3 nano-domain appears. © EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2010.

Miyazaki Y.,Kyoto University | Ohta N.,Kyoto University | Semba K.,Kyoto University | Nakao Y.,Kyoto University | Nakao Y.,Japan Science and Technology Agency
Journal of the American Chemical Society | Year: 2014

A cooperative palladium/triorganoboron catalyst to accomplish the intramolecular aminocyanation of alkenes through the cleavage of N-CN bonds is reported. 4,5-Bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos) is found to be crucial as a ligand for palladium to effectively catalyze the transformation with high chemo- and regioselectivity. A range of substituted indolines and pyrrolidines with both tetra- or trisubstituted carbon and cyano functionalities are readily furnished by the newly developed cyanofunctionalization reaction. A preliminary example of enantioselective aminocyanation is also described. © 2014 American Chemical Society.

Fujino D.,Kyoto University | Yorimitsu H.,Kyoto University | Yorimitsu H.,Japan Science and Technology Agency | Osuka A.,Kyoto University
Journal of the American Chemical Society | Year: 2014

Tuning the reactivity of arylpalladium intermediates enables control of catalytic arylative 5-exo and 6-endo cyclizations of alkynols. The two modes of cyclizations represent a rare example of controllable, regioselective difunctionalization of alkynes. The cyclizations are useful in offering a divergent synthesis of oxygen-containing heterocycles, which is of synthetic use for further derivatization. Formal synthesis of an hNK-1 receptor antagonist also showcases the utility of our arylative cyclization. © 2014 American Chemical Society.

Nakai K.,Kyoto University | Yoshida Y.,Kyoto University | Kurahashi T.,Kyoto University | Kurahashi T.,Japan Science and Technology Agency | Matsubara S.,Kyoto University
Journal of the American Chemical Society | Year: 2014

We have developed a redox-economical coupling reaction of alcohols and alkynes to form allylic alcohols under mild conditions. The reaction is redox-neutral as well as redox-economical and thus free from any additives such as a reductant or an oxidant. This atom-economical coupling can be applied for the conversion of both aliphatic and benzylic alcohols to the corresponding substituted allylic alcohols in a single synthetic operation. © 2014 American Chemical Society.

Meshcheryakov V.A.,Okinawa Institute of Science and Technology | Kitao A.,University of Tokyo | Kitao A.,Japan Science and Technology Agency | Matsunami H.,Okinawa Institute of Science and Technology | Samatey F.A.,Okinawa Institute of Science and Technology
Acta Crystallographica Section D: Biological Crystallography | Year: 2013

The membrane protein FlhB is a highly conserved component of the flagellar secretion system. It is composed of an N-terminal transmembrane domain and a C-terminal cytoplasmic domain (FlhBC). Here, the crystal structures of FlhBC from Salmonella typhimurium and Aquifex aeolicus are described at 2.45 and 2.55 Å resolution, respectively. These flagellar FlhBC structures are similar to those of paralogues from the needle type III secretion system, with the major difference being in a linker that connects the transmembrane and cytoplasmic domains of FlhB. It was found that deletion of a short flexible loop in a globular part of Salmonella FlhBC leads to complete inhibition of secretion by the flagellar secretion system. Molecular-dynamics calculations demonstrate that the linker region is the most flexible part of FlhBC and that the deletion of the loop reduces this flexibility. These results are in good agreement with previous studies showing the importance of the linker in the function of FlhB and provide new insight into the relationship between the different parts of the FlhBC molecule. © 2013 International Union of Crystallography Printed in Singapore - all rights reserved.

Wang J.,Tokyo Institute of Technology | Ueda M.,Tokyo Institute of Technology | Higashihara T.,Tokyo Institute of Technology | Higashihara T.,Japan Science and Technology Agency
ACS Macro Letters | Year: 2013

A novel initiator, N,N′-bis(2-decyltetradecyl)-2,6- dibromonaphthalene-1,4,5,8-bis(dicarboximide) (NDI-Br2), was found effective in the Kumada catalyst-transfer polycondensation (KCTP) for the synthesis of regioregular poly(3-hexylthiophene) (P3HT). In addition, a two-step method of synthesizing all-conjugated triblock copolymers comprised of both n-type and p-type blocks was proposed. With a 10:9 feed molar ratio of NDI-Br2 to 2,5-bis(trimethylstannyl)thiophene, an n-type macroinitiator (PNDITh-Br2) was prepared via the Stille coupling reaction. Two outer P3HT blocks were then emanated via KCTP initiated by PNDITh-Br2 to produce all-conjugated ABA-type triblock copolymers. The size exclusion chromatography (SEC) curves of all the triblock copolymers showed narrow distribution, with the lowest polydispersity index (PDI) of 1.15. Moreover, the molecular weight of the block copolymer was found to be independent of the amount of Ni catalyst, while it can be tailored by the feed molar ratio of the thiophene monomer to PNDITh-Br2. The transmission electron microscopy (TEM) images and grazing-incidence wide-angle X-ray scattering (GIWAXS) patterns of the block copolymer thin film revealed a well-defined lamellar structure and two distinguished crystalline domains, where the P3HT layer was in the range of 10-20 nm and presented an edge-on rich alignment. © 2013 American Chemical Society.

Yamamoto S.,Kyoto University | Orimo A.,Kyoto University | Ohkita H.,Kyoto University | Ohkita H.,Japan Science and Technology Agency | And 2 more authors.
Advanced Energy Materials | Year: 2012

The origin of open-circuit voltage (V OC) was studied for polymer solar cells based on a blend of poly(3-hexylthiophene) (P3HT) and seven fullerene derivatives with different LUMO energy levels and side chains. The temperature dependence of J-V characteristics was analyzed by an equivalent circuit model. As a result, V OC increased with the decrease in the saturation current density J 0 of the device. Furthermore, J 0 was dependent on the activation energy E A for J 0, which is related to the HOMO-LUMO energy gap between P3HT and fullerene. Interestingly, the pre-exponential term J 00 for J 0 was larger for pristine fullerenes than for substituted fullerene derivatives, suggesting that the electronic coupling between molecules also has substantial impact on V OC. This is probably because the recombination is non-diffusion-lmilited reaction depending on electron transfer at the P3HT/fullerene interface. In summary, the origin of V OC is ascribed not only to the relative HOMO-LUMO energy gap but also to the electronic couplings between fullerene/fullerene and polymer/fullerene. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Yamauchi Y.,Japan International Center for Materials Nanoarchitectonics | Yamauchi Y.,Japan Science and Technology Agency
Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan | Year: 2013

Mesoporous materials prepared through the self-assembly of surfactants have attracted wide attention because of their many potential applications. The mesostructural, compositional, and morphological controls of mesoporous materials have been extensively studied thus far. In particular, the macroscopic alignments of one-dimensional (1D) mesochannels and their controls are quite important for the creation of advanced functional materials. In most cases, the direction of mesochannels in mesoporous films lies parallel to the substrate. Vertical orientation of the mesochannels can realize high diffusion and accessibility of guest species from the outside. Here, I review the recent progress on this emerging research field. Various methods have been proposed for the preparation of vertically oriented mesoporous thin films using high magnetic field, shear flow, modification of the substrate, and other methods. I also briefly introduce their applications and a perspective for the future. © 2013 The Ceramic Society of Japan. All rights reserved.

Fujimoto K.,Kyoto University | Yoneda T.,Kyoto University | Yorimitsu H.,Kyoto University | Yorimitsu H.,Japan Science and Technology Agency | Osuka A.,Kyoto University
Angewandte Chemie - International Edition | Year: 2014

2,18-Bis(diphenylphosphino)porphyrins undergo peripheral cyclometalation with group 10 transition-metal salts to afford the corresponding porphyrin-based PCP pincer complexes. The porphyrinic plane and the PCP-pincer unit are apparently coplanar, with small strain. The catalytic activities of the porphyrin-based pincer complexes at the periphery were investigated in the allylation of benzaldehyde with allylstannane and in the 1,4-reduction of chalcone to discover the electronic interplay between the inner metal and the outer metal in catalysis. Metals at play: 2,18-Bis(diphenylphosphino)porphyrins undergo peripheral cyclometalation with group 10 transition-metal salts to afford the corresponding porphyrin-based PCP pincer complexes. The catalytic activities of the porphyrin-based pincer complexes were investigated in the allylation of benzaldehyde with allylstannane and in the 1,4-reduction of chalcone (see scheme) to assess the electronic interplay between the inner metal and the outer metal in catalysis. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oji K.,Osaka University | Igashira-Kamiyama A.,Osaka University | Yoshinari N.,Osaka University | Konno T.,Osaka University | Konno T.,Japan Science and Technology Agency
Angewandte Chemie - International Edition | Year: 2014

A novel AuICoIII coordination system that is derived from the newly prepared [Co(D-nmp)2]- (1-; D-nmp=N-methyl-D-penicillaminate) and a gold(I) precursor AuI is reported. Complex 1- acts as a sulfur-donating metallaligand and reacts with the gold(I) precursor to give [Au2Co2(D-nmp) 4] (2), which has an eight-membered AuI2Co III2 metallaring. Treatment of 2 with [Au 2(dppe)2]2+ (dppe=1,2-bis(diphenylphosphino) ethane) leads to the formation of [Au4Co2(dppe) 2(D-nmp)4]2+ (32+), which consists of an 18-membered AuI4CoIII2 metallaring that accommodates a tetrahedral anion (BF4-, ClO4-, ReO4-). In solution, the metallaring structure of 32+ is readily interconvertible with the nine-membered AuI2CoIII metallaring structure of [Au2Co(dppe)(D-nmp)2]+ (4+); this process depends on external factors, such as solvent, concentration, and nature of the counteranion. These results reveal the lability of the Au=S and Au=P bonds, which is essential for metallaring expansion and contraction. The eight-membered AuI2CoIII2 metallaring in [Au2Co2(D-nmp)4] (D-nmp=N-methyl-D-penicillaminate) was synthesized from [Co(D-nmp) 2]- and a gold(I) precursor. By treatment with [Au 2(dppe)2]2+ (dppe=1,2-bis(diphenylphosphino) ethane), this metallaring could be rationally expanded to the eighteen-membered AuI4CoIII2 metallaring in [Au 4Co2(dppe)2(D-nmp)4]2+, which also accommodates a tetrahedral anion inside the ring. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sahara G.,Tokyo Institute of Technology | Ishitani O.,Tokyo Institute of Technology | Ishitani O.,Japan Science and Technology Agency
Inorganic Chemistry | Year: 2015

Three types of photocatalytic systems for CO2 reduction, which were recently developed in our group, are reviewed. First, two-component systems containing different rhenium(I) complexes having different roles; i.e., redox photosensitizer and catalyst in the reaction solution are described. The mixed system of a ring-shaped rhenium(I) trinuclear complex and fac-[Re(bpy)(CO)3(MeCN)]+ is currently the most efficient photocatalytic system for CO2 reduction (φCO = 0.82 at ex = 436 nm). The second is a series of supramolecular photocatalysts, which have units with different functions in one molecule, i.e., redox photosensitizer, catalyst, and bridging ligand. The highest durability and speed of photocatalysis were achieved by using this system (φCO = 0.45, TONCO = 3029, and TOFCO = 35.7 min-1). The third is a novel type of artificial Z-Scheme photocatalyst for CO2 reduction, of which photocatalysis is revealed by stepwise excitation of both a semiconductor photocatalyst unit and the supramolecular photocatalyst unit. This system has both strong oxidation and reduction powers. © 2015 American Chemical Society.

Ogawa H.,Hokkaido University | Ogawa H.,Japan Science and Technology Agency | Oka K.,Keio University
Journal of Neuroscience | Year: 2015

Stimulus-specific adaptation (SSA) is considered to be the neural underpinning of habituation to frequent stimuli and novelty detection. However, neither the cellular mechanism underlying SSA nor the link between SSA-like neuronal plasticity and behavioral modulation is well understood. The wind-detection system in crickets is one of the best models for investigating the neural basis of SSA. We found that crickets exhibit stimulus-direction-specific adaptation in wind-elicited avoidance behavior. Repetitive air currents inducing this behavioral adaptation reduced firings to the stimulus and the amplitude of excitatory synaptic potentials in wind-sensitive giant interneurons (GIs) related to the avoidance behavior. Injection of a Ca2+ chelator into GIs diminished both the attenuation of firings and the synaptic depression induced by the repetitive stimulation, suggesting that adaptation of GIs induced by this stimulation results in Ca2+-mediated modulation of postsynaptic responses, including postsynaptic short-term depression. Some types of GIs showed specific adaptation to the direction of repetitive stimuli, resulting in an alteration of their directional tuning curves. The types of GIs for which directional tuning was altered displayed heterogeneous direction selectivity in their Ca2+ dynamics that was restricted to a specific area of dendrites. In contrast, other types of GIs with constant directionality exhibited direction-independent global Ca2+ elevation throughout the dendritic arbor. These results suggest that depression induced by local Ca2+ accumulation at repetitively activated synapses of key neurons underlies direction-specific behavioral adaptation. This input-selective depression mediated by heterogeneous Ca2+ dynamics could confer the ability to detect novelty at the earliest stages of sensory processing in crickets. © 2015 the authors.

Ohtsuki H.,Graduate University for Advanced Studies | Ohtsuki H.,Japan Science and Technology Agency
Journal of Theoretical Biology | Year: 2012

Recent developments of social evolution theory have revealed conditions under which cooperation is favored by natural selection. Effects of population structure on the evolution of cooperation have been one of the central questions in this issue, and inclusive fitness analyses have unveiled two different selective forces that favor cooperation; the direct fitness effect to the helper and the indirect fitness benefit to the helper via its kin. Although these theoretical frameworks have made a significant contribution to our understanding of cooperative traits, there is still one factor to be taken into account, synergy. Synergy means a nonlinear effect that arises when two individuals help each other. In other words, it represents deviation from additivity, to which inclusive fitness theory has paid relatively little attention. Here I provide a theoretical result on the possibility that synergy favors the evolution of cooperation. For homogeneously structured populations with non-overlapping generations, I show that incorporating synergistic effects does not rescue the evolution of cooperation. Potential factors that could enable synergy to rescue the evolution of cooperation are also discussed. © 2012 Elsevier Ltd.

Osaka I.,Hiroshima University | Osaka I.,Japan Science and Technology Agency | Osaka I.,RIKEN | Saito M.,Hiroshima University | And 3 more authors.
Advanced Materials | Year: 2014

The backbone orientation in the thiophene-thiazolothiazole (TzTz) copolymer system can be altered by tuning of the alky side chain composition. We highlight that the orientation significantly impact their solar cell efficiency in particular when using thicker active layers. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Song J.,Kyoto University | Aratani N.,Kyoto University | Aratani N.,Japan Science and Technology Agency | Shinokubo H.,Nagoya University | Osuka A.,Kyoto University
Journal of the American Chemical Society | Year: 2010

A porphyrin nanobarrel, 1, that can encapsulate C60 effectively was prepared via a concise coupling route. The structures of both 1 and C 60@1 were confirmed by single-crystal X-ray diffraction analysis. © 2010 American Chemical Society.

Kondo M.,Kyoto University | Furukawa S.,Kyoto University | Furukawa S.,Japan Science and Technology Agency | Hirai K.,Kyoto University | Kitagawa S.,Kyoto University
Angewandte Chemie - International Edition | Year: 2010

Surface-specific: Coordinatively immobilized monolayers (CIMs) of fluorescent dyes were fabricated on specific single-crystal surfaces of porous coordination polymers (PCPs) (see picture). This approach enables the fabrication of functional PCP crystal surfaces with precisely controlled fluorescent gating and sensing properties. (Figure Presented). © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

Uyanik M.,Nagoya University | Yasui T.,Nagoya University | Ishihara K.,Nagoya University | Ishihara K.,Japan Science and Technology Agency
Angewandte Chemie - International Edition | Year: 2010

"Chemical Equation Presented" The iodines(lll) have it: The rational design of a conformationals/ flexible C 2symmetric iodosylarene catalyst has been used for the enantioselective Kita oxidative spirolactonization. The reaction occurs through secondary n-σ* or hydrogen-bonding interactions between the chiral catalyst and the substrate. Mes = mesityl (2,4,6-trimethylphenyl). © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

Takamizawa S.,Yokohama City University | Takamizawa S.,Japan Science and Technology Agency | Takasaki Y.,Yokohama City University | Miyake R.,Yokohama City University
Journal of the American Chemical Society | Year: 2010

(Figure Presented) Development of gas separation materials has been one of the basic requirements of industry. Microporous materials have adequate pores for gas separation and have contributed to the advancement of gas purification techniques. Because the simplest and most economical method would be membrane separation, various microporous membranes have been prepared and explored for their separation properties. However, a key issue remains as to how to generate defect-free membranes with practical gas permeance. Here we report the preparation of a well-oriented single-crystal membrane with high permeance by using a flexible single crystal of [Cu2(bza)4(pyz)] n possessing one-dimensional (1D) penetration channels; this membrane exhibits anisotropic gas permeation through the 1D channels with high permselectivity for H2 and CO2. Although the diameter of the neck of the narrow channels is smaller than the kinetic diameters of the sample gases, various gases pass through the 1D channels. This report provides a new way of developing gas permeation membranes as sophisticated crystal devices for gas purification techniques. Copyright © 2010 American Chemical Society.

Noda N.N.,Institute of Microbial Chemistry BIKAKEN | Noda N.N.,Japan Science and Technology Agency | Fujioka Y.,Institute of Microbial Chemistry BIKAKEN
Cellular and Molecular Life Sciences | Year: 2015

Autophagosome formation, a landmark event in autophagy, is accomplished by the concerted actions of Atg proteins. Among all Atg proteins, Atg1 kinase in yeast and its counterpart in higher eukaryotes, ULK1 kinase, function as the most upstream factor in this process and mediate autophagy initiation. In this review, we summarize current knowledge of the structure, molecular function, and regulation of Atg1 family kinases in the initiation of autophagy. © 2015 The Author(s).

Nakagawa S.,RIKEN | Nakagawa S.,Japan Science and Technology Agency | Prasanth K.V.,University of Illinois at Urbana - Champaign
Trends in Cell Biology | Year: 2011

X-chromosome inactivation has long served as an experimental model system for understanding the epigenetic regulation of gene expression. Central to this phenomenon is the long, non-coding RNA Xist that is specifically expressed from the inactive X chromosome and spreads along the entire length of the chromosome in cis. Recently, two of the proteins originally identified as components of the nuclear scaffold/matrix (S/MAR-associated proteins) have been shown to control the principal features of X-chromosome inactivation; specifically, context-dependent competency and the chromosome-wide association of Xist RNA. These findings implicate the involvement of nuclear S/MAR-associated proteins in the organization of epigenetic machinery. Here, we describe a model for the functional role of S/MAR-associated proteins in the regulation of key epigenetic processes. © 2011 Elsevier Ltd.

Honda S.,Kyoto University | Ohkita H.,Kyoto University | Ohkita H.,Japan Science and Technology Agency | Benten H.,Kyoto University | Ito S.,Kyoto University
Advanced Energy Materials | Year: 2011

Selective dye loading at the polymer/fullerene interface was studied for ternary blend bulk heterojunction solar cells, consisting of regioregular poly(3-hexylthiophene) (RR-P3HT), a fullerene derivative (PCBM), and a silicon phthalocyanine derivative (SiPc) as a light-harvesting dye. The photocurrent density and power conversion efficiency of the ternary blend solar cells were most improved by loading SiPc with a content of 4.8 wt%. The absorption and surface energy measurements suggested that SiPc is located in the disordered P3HT domains at the RR-P3HT/PCBM interface rather than in the PCBM and crystal P3HT domains. From the peak wavelength of SiPc absorption, the local concentration of SiPc ([SiPc] Local) was estimated for the RR-P3HT:PCBM:SiPc ternary blends. Even for amorphous films of regiorandom P3HT (RRa-P3HT) blended with PCBM and SiPc, [SiPc] Local was higher than the original content, suggesting dye segregation into the RRa-P3HT/PCBM interface. For RR-P3HT:PCBM:SiPc blends, [SiPc] Local increased with the increase in the P3HT crystallinity. Such interfacial segregation of dye molecules in ternary blend films can be rationally explained in terms of the surface energy of each component and the crystallization of P3HT being enhanced by annealing. Notably, the solvent annealing effectively segregated dye molecules into the interface without the formation of PCBM clusters. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tokiwa Y.,University of Gottingen | Ishikawa J.J.,University of Tokyo | Nakatsuji S.,University of Tokyo | Nakatsuji S.,Japan Science and Technology Agency | And 2 more authors.
Nature Materials | Year: 2014

When magnetic order is suppressed by frustrated interactions, spins form a highly correlated fluctuating 'spin liquid' state down to low temperatures. The magnetic order of local moments can also be suppressed when they are fully screened by conduction electrons through the Kondo effect. Thus, the combination of strong geometrical frustration and Kondo screening may lead to novel types of quantum phase transition. We report low-temperature thermodynamic measurements on the frustrated Kondo lattice Pr 2 Ir 2 O 7, which exhibits a chiral spin liquid state below 1.5 K as a result of the frustrated interaction between Ising 4f local moments and their interplay with Ir conduction electrons. Our results provide a first clear example of zero-field quantum critical scaling that emerges in a spin liquid state of a highly frustrated metal. © 2014 Macmillan Publishers Limited. All rights reserved.

Mano H.,Jichi Medical University | Mano H.,Tokyo Medical University | Mano H.,Japan Science and Technology Agency
Cancer Discovery | Year: 2012

Anaplastic lymphoma kinase (ALK) is a receptor-type protein tyrosine kinase that is currently the focus of much attention in oncology. ALK is rendered oncogenic as a result of its fusion to NPM1 in anaplastic large cell lymphoma, to TPM3 or TPM4 in inflammatory myofibroblastic tumor, to EML4 in non-small cell lung carcinoma, and to VCL in renal medullary carcinoma. It is also activated as a result of missense mutations in neuroblastoma and anaplastic thyroid cancer. Whereas these various tumors arise in different organs, they share activated ALK, and a marked clinical efficacy with ALK inhibitors has already been shown for some of the tumors with ALK fusions. One of such compound, crizotinib, is now approved in the United States for the treatment of lung cancer positive for ALK rearrangement. I propose that tumors carrying abnormal ALK as an essential growth driver be collectively termed "ALKoma." Significance: ALK acquires transforming ability through gene fusion or missense mutation in a wide range of human cancers. Some of these cancers, which I propose be collectively referred to as "ALKoma," may all be effectively treated with small compounds or antibodies targeted to activated ALKs. © 2012 American Association for Cancer Research.

Yamamoto T.,Kyoto University | Akai Y.,Kyoto University | Suginome M.,Kyoto University | Suginome M.,Japan Science and Technology Agency
Angewandte Chemie - International Edition | Year: 2014

Post-polymerization C-H activation of poly(quinoxaline-2,3-diyl)-based helically chiral phosphine ligands (PQXphos) with palladium(II) acetate afforded chiral phosphapalladacycles quantitatively. In situ generated palladacycles exhibited enantioselectivities up to 94 % ee in the palladium-catalyzed asymmetric ring-opening arylation of 1,4-epoxy-1,4-dihydronaphthalenes with arylboronic acids. Polymers with a twist: Poly(quinoxaline-2,3-diyl)-based helically chiral phosphine ligands (PQXphos) have been used to generate chiral phosphapalladacycles. The palladacycles resulted in enantioselectivities of up to 94 % ee in the palladium-catalyzed asymmetric ring-opening arylation of 1,4-epoxy-1,4-dihydronaphthalenes with arylboronic acids. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tanaka K.,Japan Science and Technology Agency
Energy Policy | Year: 2011

Energy efficiency in industry plays key roles in improving energy security, environmental sustainability and economic performance. It is particularly important in strategies to mitigate climate change. The evidence of great potential for cost-effective efficiency-derived reductions in industrial energy use and greenhouse gas (GHG) emissions have prompted governments to implement numerous policies and measures aimed at improving their manufacturing industries' energy efficiency. What can be learned from these many and varied initiatives? This paper provides foundation for policy analysis for enhancing energy efficiency and conservation in industry, by surveying more than 300 policies, encompassing about 570 measures, implemented by governments in IEA countries, Brazil, China, India, Mexico, Russia and South Africa. It outlines the measures' main features, their incidence of use, and their connections with specific technical actions and key stakeholders (i.e., how and where measures affect the energy efficiency of industry). It also examines the key features underlying the measures' success: (1) potential to reduce energy use and CO2 emissions cost-efficiently; (2) ease of policy development, execution and assessment and (3) ancillary societal effects. © 2011 Elsevier Ltd.

Hasegawa Y.,RIKEN | Hasegawa Y.,University of Tokyo | Brockdorff N.,University of Oxford | Kawano S.,Okayama University | And 3 more authors.
Developmental Cell | Year: 2010

In XX female mammals, one of the two X chromosomes is epigenetically inactivated to equalize gene expression with XY males. The formation of the inactive X chromosome (Xi) is regulated by an X-linked long noncoding RNA Xist, which accumulates on the entire length of the chromosome in cis and induces heterochromatin formation. However, the mechanism by which Xist RNA "paints" the Xi has long remained elusive. Here, we show that a matrix protein hnRNP U/SP120/SAF-A is required for the accumulation of Xist RNA on the Xi. Xist RNA and hnRNP U interact and upon depletion of hnRNP U, Xist RNA is detached from the Xi and diffusely localized into the nucleoplasm. In addition, ES cells lacking hnRNP U expression fail to form the Xi. We propose that the association with matrix proteins is an essential step in the epigenetic regulation of gene expression by Xist RNA. © 2010 Elsevier Inc.

Inoue K.,Nagoya Institute of Technology | Inoue K.,Japan Science and Technology Agency | Kato Y.,Nagoya Institute of Technology | Kandori H.,Nagoya Institute of Technology
Trends in Microbiology | Year: 2015

Microbial rhodopsins are the photoreceptive membrane proteins found in diverse microorganisms from within Archaea, Eubacteria, and eukaryotes. They have a heptahelical transmembrane structure that binds to an all- trans retinal chromophore. Since 2000, thousands of proteorhodopsins, genes of light-driven proton pump rhodopsins, have been identified from various species of marine bacteria. This suggests that they are used for the conversion of light into chemical energy, contributing to carbon circulation related to ATP synthesis in the ocean. Furthermore, novel types of rhodopsin (sodium and chloride pumps) have recently been discovered. Here, we review recent progress in our understanding of ion-transporting rhodopsins of marine bacteria, based mainly on biophysical and biochemical research. © 2014 Elsevier Ltd.

Maeda K.,Tokyo Institute of Technology | Maeda K.,Japan Science and Technology Agency | Lu D.,Tokyo Institute of Technology | Domen K.,University of Tokyo
Angewandte Chemie - International Edition | Year: 2013

Water splitting: In heterogeneous photocatalysis, it has been believed that doping transition-metal cations having partly filled d orbitals into semiconductor photocatalysts results in a significant drop in photocatalytic activity. Nevertheless, it was found that the activity for the water oxidation of BaTaO2N could be improved by seven times upon modification by pentavalent W species (see picture). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nagai A.,Japan Institute for Molecular Science | Chen X.,Japan Institute for Molecular Science | Feng X.,Japan Institute for Molecular Science | Ding X.,Japan Institute for Molecular Science | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2013

π in the sky: A squaraine-linked, conjugated two-dimensional porphyrin covalent organic framework (COF; see scheme; C: gray, H: white, N: blue, Cu: red) was synthesized. Owing to the π-conjugated linkage together with the eclipsed stacking of the units, this COF exhibits enhanced chemical and thermal stabilities. It absorbs a broad range of light, from the ultraviolet to the visible, and near-infrared regions, and shows potential as a photocatalyst. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hatakeyama T.,Kyoto University | Hatakeyama T.,Japan Science and Technology Agency | Hashimoto S.,Kyoto University | Oba T.,Kyoto University | Nakamura M.,Kyoto University
Journal of the American Chemical Society | Year: 2012

Azaboradibenzo[6]helicene, a new semiconductor material possessing helical chirality, has been synthesized via a tandem bora-Friedel-Crafts-type reaction. Unprecedented carrier inversion between the racemate (displaying p-type semiconductivity) and the single enantiomer (displaying n-type semiconductivity) was observed and can be explained by changes in the molecular packing induced by helical homochirality. © 2012 American Chemical Society.

Arita M.,University of Tokyo | Arita M.,Japan Science and Technology Agency
Journal of Biochemistry | Year: 2012

Acute inflammation is an indispensable host response to foreign challenges or tissue injury. In healthy conditions, inflammatory processes are self-limiting and self-resolving, suggesting the existence of endogenous mechanisms for the control of inflammation and resolution. A comprehensive understanding of the cellular and molecular events of a well-orchestrated inflammatory response is required, and recent studies have uncovered the roles of endogenous lipid mediators derived from polyunsaturated fatty acids (i.e. lipoxins, resolvins, protectins) in controlling the resolution of inflammation. This review presents recent advances in understanding the formation and action of these mediators, especially focusing on the LC-MS/MS-based lipidomics approach and the emerging roles of eosinophils and eosinophil-derived lipid mediators in controlling acute inflammation and resolution. © The Authors 2012. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

Shigematsu A.,Kyoto University | Shigematsu A.,Kyushu University | Yamada T.,Kyoto University | Kitagawa H.,Kyoto University | And 2 more authors.
Journal of the American Chemical Society | Year: 2012

A novel porous coordination polymer, CuII(mtpm)Cl2 [mtpm = tetrakis(m-pyridyloxy methylene)methane], has been synthesized, and its crystal structure has been determined. Its adsorption isotherms for water, methanol, and ethanol are totally different from each other. It adsorbs water at low humidity and shows gate-open behavior for methanol, but it does not adsorb ethanol. This compound has the capacity to separate both methanol and water from bioethanol, which is a mixture of water, methanol, and ethanol. © 2012 American Chemical Society.

Setaka W.,Tokushima Bunri University | Setaka W.,Japan Science and Technology Agency | Yamaguchi K.,Tokushima Bunri University
Journal of the American Chemical Society | Year: 2012

A macrocage molecule with a bridged phenylene rotor has been reported as a molecular gyrotop, because the rotor can rotate even in a crystalline state. Although the most stable cage structure of the molecular gyrotop in a crystal was folded and shrunken at low temperature, expansion of the cage was observed at high temperature due to rapid rotation of the phenylene in a crystal. This phenomenon is analogous to the deflation and inflation of a balloon. Moreover, the unusually large thermal expansion coefficient of the crystal was estimated in the temperature range in which the expansion of the cage was observed, indicating a new function of dynamic states of the molecules. © 2012 American Chemical Society.

Endo Y.,Chiba University | Hirahara K.,Chiba University | Yagi R.,Chiba University | Tumes D.J.,Chiba University | And 2 more authors.
Trends in Immunology | Year: 2014

Immunological memory is a hallmark of adaptive immunity. Memory CD4 T helper (Th) cells are central to acquired immunity, and vaccines for infectious diseases are developed based on this concept. However, memory Th cells also play a critical role in the pathogenesis of various chronic inflammatory diseases, including asthma. We refer to these populations as 'pathogenic memory Th cells.' Here, we review recent developments highlighting the functions and characteristics of several pathogenic memory type Th2 cell subsets in allergic inflammation. Also discussed are the similarities and differences between pathogenic memory Th2 cells and recently identified type 2 innate lymphoid cells (ILC2), focusing on cytokine production and phenotypic profiles. © 2013 Elsevier Ltd.

Endo K.,Kanazawa University | Endo K.,Japan Science and Technology Agency | Hamada D.,Waseda University | Yakeishi S.,Waseda University | Shibata T.,Waseda University
Angewandte Chemie - International Edition | Year: 2013

Al and friends: Asymmetric conjugate addition of Me3Al to β,β-disubstituted α,β-unsaturated ketones in the presence copper and L1 leads to a highly efficient construction of an all-carbon-substituted chiral quaternary center. This result is the first example of an asymmetric conjugate addition of Me3Al to acyclic enones to give a chiral quaternary carbon center with excellent yield and enantioselectivity under mild reaction conditions. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hu M.,Japan National Institute of Materials Science | Ishihara S.,Japan National Institute of Materials Science | Yamauchi Y.,Japan National Institute of Materials Science | Yamauchi Y.,Waseda University | Yamauchi Y.,Japan Science and Technology Agency
Angewandte Chemie - International Edition | Year: 2013

A two-dimensional morphology characterizes the nanoflakes that are obtained in the bottom-up synthesis of a single-crystalline coordination polymer, Ni(H2O)2[Ni(CN)4]×x H2O. The 10 nm-thick nanoflakes are well-dispersed in solution and have a very high accessible surface area (240 m2 g-1). Thermal treatment leads to nanoporous NiO with retention of the original flake morphology. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sato S.,Toyota Central Research and Development Laboratories Inc. | Sato S.,Japan Science and Technology Agency | Morikawa T.,Toyota Central Research and Development Laboratories Inc. | Kajino T.,Toyota Central Research and Development Laboratories Inc. | Ishitani O.,Tokyo Institute of Technology
Angewandte Chemie - International Edition | Year: 2013

Mononuclear iridium(III) terpyridine (tpy) 2-phenylpyridine (ppy) complexes [Ir(tpy)(R-ppy)Cl] (R=H, Me, CF3) can act as efficient and selective CO2 reduction photocatalysts. The reaction is driven using visible light in a homogeneous solution, and even in a H2O mixed solution. The most efficient photocatalyst is [Ir(tpy)(Me-ppy)Cl], for which the turnover in CO was over 50 and the quantum yield was 0.21 at 480 nm. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Unoh Y.,Osaka University | Hirano K.,Osaka University | Satoh T.,Osaka University | Satoh T.,Japan Science and Technology Agency | Miura M.,Osaka University
Angewandte Chemie - International Edition | Year: 2013

Benzophosphole construction was achieved through the AgI- mediated dehydrogenative annulation of phenylphosphine oxides with internal alkynes in a process involving C - C and C - P bond formation. A wide range of asymmetrical phenylacetylenes could be employed and the reactions proceeded with perfect regioselectivity. Moreover, the annulation could be conducted even at room temperature when a MnIII promoter was used in place of Ag I. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kidoya H.,Osaka University | Takakura N.,Osaka University | Takakura N.,Japan Science and Technology Agency
Journal of Biochemistry | Year: 2012

Apelin is a bioactive peptide with diverse physiological actions on many tissues mediated by its interaction with its specific receptor APJ. Since the identification of apelin and APJ in 1998, pleiotropic roles of the apelin/APJ system have been elucidated in different tissues and organs, including modulation of the cardiovascular system, fluid homeostasis, metabolic pathway and vascular formation. In blood vessels, apelin and APJ expression are spatiotemporally regulated in endothelial cells (ECs) during angiogenesis. In vitro analysis revealed that the apelin/APJ system regulates angiogenesis by the induction of proliferation, migration and cord formation of cultured ECs. Moreover, apelin seems to stabilize cell-cell junctions of ECs. In addition, genetically engineered mouse models suggest that apelin/APJ regulates vascular stabilization and maturation in physiological and pathological angiogenesis. In this review, we summarize the current understanding of the apelin/APJ system for vascular formation and maturation. © 2012 The Authors.

Mukaida N.,Kanazawa University | Mukaida N.,Japan Science and Technology Agency | Baba T.,Kanazawa University
Experimental Cell Research | Year: 2012

Chemokines were originally identified as mediators of the inflammatory process and regulators of leukocyte trafficking. Subsequent studies revealed their essential roles in leukocyte physiology and pathology. Moreover, chemokines have profound effects on other types of cells associated with the inflammatory response, such as endothelial cells and fibroblasts. Thus, chemokines are crucial for cancer-related inflammation, which can promote tumor development and progression. Increasing evidence points to the vital effects of several chemokines on the proliferative and invasive properties of tumor cells. The wide range of activities of chemokines in tumorigenesis highlights their roles in tumor development and progression. © 2011 Elsevier Inc.

Nakahata M.,Osaka University | Takashima Y.,Osaka University | Hashidzume A.,Osaka University | Harada A.,Osaka University | Harada A.,Japan Science and Technology Agency
Angewandte Chemie - International Edition | Year: 2013

A supramolecular hydrogel is formed by a water-soluble polymer cross-linked with host-guest inclusion complexes between cyclodextrin and ferrocene. Dissociation and re-formation of inclusion complexes by redox stimuli lead to macroscale expansion and contraction of the hydrogel. The gel is utilized as a redox-responsive actuator and the mechanical work done is evaluated. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Shibuya A.,University of Tsukuba | Shibuya A.,Japan Science and Technology Agency | Honda S.-I.,University of Tsukuba
Immunological Reviews | Year: 2015

Although both Fcα/μ receptor (Fcα/μR) and polymeric Ig receptor (poly-IgR) are Fc receptors for IgA and IgM and are functionally and genetically related, the expression profile of Fcα/μR is unique. Unlike poly-IgR, Fcα/μR is expressed on marginal zone (MZ) B cells and follicular dendritic cells, suggesting that Fcα/μR plays an important role in humoral immune responses. Fcα/μR mediates endocytosis of the IgM immune complex (IC). Recent research demonstrated that Fcα/μR downregulated retention of the IgM IC with a T-independent (TI) antigen on MZ B cells and follicular dendritic cells due to endocytosis of the IgM IC, suppressing germinal center formation, affinity maturation, and memory B-cell generation in response to TI antigen challenge. In addition, Fcα/μR physically associates with Toll-like receptor 4 (TLR4) and augments TLR4 oligomerization and signaling in MZ B cells upon lipopolysaccharide (LPS) challenge, leading to increased proinflammatory cytokine production by MZ B cells. Thus, Fcα/μR is a unique Fc receptor that is involved in humoral immune responses and inflammation. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Tabei Y.,Japan Science and Technology Agency
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

Similarity searches in the databases of chemical fingerprints are a fundamental task in discovering novel drug-like molecules. Multibit trees have a data structure that enables fast similarity searches of chemical fingerprints (Kristensen et al., WABI'09). A standard pointer-based representation of multibit trees consumes a large amount of memory to index large-scale fingerprint databases. To make matters worse, original fingerprint databases need to be stored in memory to filter out false positives. A succinct data structure is compact and enables fast operations. Many succinct data structures have been proposed thus far, and have been applied to many fields such as full text indexing and genome mapping. We present compact representations of both multibit trees and fingerprint databases by applying these data structures. Experiments revealed that memory usage in our representations was much smaller than that of the standard pointer-based representation. Moreover, our representations enabled us to efficiently perform PubChem-scale similarity searches. © 2012 Springer-Verlag.

Chandra D.,Niigata University | Saito K.,Niigata University | Yui T.,Niigata University | Yagi M.,Niigata University | Yagi M.,Japan Science and Technology Agency
Angewandte Chemie - International Edition | Year: 2013

Small mesopores are more efficient: A mesoprous oxide semiconductor (tungsten trioxide) having small mesopores was crystallized at high temperature (550 °C) by a simple one-step procedure. The highly crystalline mesoporous WO3 has an extremely high surface area which improves the visible-light-driven photoelectrochemical performance of water oxidation (see picture) relative to WO3 having interparticle mesopores. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Uyanik M.,Nagoya University | Yasui T.,Nagoya University | Ishihara K.,Nagoya University | Ishihara K.,Japan Science and Technology Agency
Angewandte Chemie - International Edition | Year: 2013

Iodine chooses: A conformationally flexible C2-symmetric organoiodine(III) catalyst for the highly enantioselective catalytic oxidative dearomatization of phenols has been developed. Catalysis is controlled by intramolecular hydrogen-bonding interactions and additional achiral alcohols. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kato H.,Kyoto University | Kato H.,Japan Science and Technology Agency | Fujita T.,Kyoto University
Current Opinion in Immunology | Year: 2015

Type I interferon (IFN) plays an essential role in antiviral innate immune responses and also in adaptive immune responses. Defects in the production of IFN markedly increase susceptibility to viral invasion and attenuate the acquired immunity. Recently an increased expression of type I IFN, also termed IFN signature, has been reported in patients with autoimmune diseases such as systemic lupus erythematosus (SLE) and Aicardi-Goutières syndrome (AGS). The evidence clearly shows that the initiation and termination of IFN production should be tightly controlled. RIG-I-like receptors (RLRs) are viral RNA sensors and are essential for type I IFN induction. We herein summarize recent reports on RLR mutations in patients and MDA5 mutant mice, and discuss possible mechanisms by which aberrant activation of RLRs can cause autoimmunity. © 2015 Elsevier Ltd.

Osaka I.,Hiroshima University | Osaka I.,Japan Science and Technology Agency | Shimawaki M.,Hiroshima University | Mori H.,Hiroshima University | And 4 more authors.
Journal of the American Chemical Society | Year: 2012

We report the synthesis and characterization of a novel donor-acceptor semiconducting polymer bearing naphthobisthiadiazole (NTz), a doubly benzothiadiazole (BTz)-fused ring, and its applications to organic field-effect transistors and bulk heterojunction solar cells. With NTz's highly π-extended structure and strong electron affinity, the NTz-based polymer (PNTz4T) affords a smaller bandgap and a deeper HOMO level than the BTz-based polymer (PBTz4T). PNTz4T exhibits not only high field-effect mobilities of ∼0.56 cm 2/(V s) but also high photovoltaic properties with power conversion efficiencies of ∼6.3%, both of which are significantly high compared to those for PBTz4T. This is most likely due to the more suitable electronic properties and, importantly, the more highly ordered structure of PNTz4T in the thin film than that of PBTz4T, which might originate in the different symmetry between the cores. NTz, with centrosymmetry, can lead to a more linear backbone in the present polymer system than BTz with axisymmetry, which might be favorable for better molecular ordering. These results demonstrate great promise for using NTz as a bulding unit for high-performance semiconducting polymers for both transistors and solar cells. © 2012 American Chemical Society.

Arai M.,Scripps Research Institute | Arai M.,Japan National Institute of Advanced Industrial Science and Technology | Arai M.,University of Tokyo | Arai M.,Japan Science and Technology Agency | And 2 more authors.
Journal of the American Chemical Society | Year: 2012

Determination of affinities and binding sites involved in protein-ligand interactions is essential for understanding molecular mechanisms in biological systems. Here we combine singular value decomposition and global analysis of NMR chemical shift perturbations caused by protein-protein interactions to determine the number and location of binding sites on the protein surface and to measure the binding affinities. Using this method we show that the isolated AD1 and AD2 binding motifs, derived from the intrinsically disordered N-terminal transactivation domain of the tumor suppressor p53, both interact with the TAZ2 domain of the transcriptional coactivator CBP at two binding sites. Simulations of titration curves and line shapes show that a primary dissociation constant as small as 1-10 nM can be accurately estimated by NMR titration methods, provided that the primary and secondary binding processes are coupled. Unexpectedly, the site of binding of AD2 on the hydrophobic surface of TAZ2 overlaps with the binding site for AD1, but AD2 binds TAZ2 more tightly. The results highlight the complexity of interactions between intrinsically disordered proteins and their targets. Furthermore, the association rate of AD2 to TAZ2 is estimated to be 1.7 × 10 10 M -1 s -1, approaching the diffusion-controlled limit and indicating that intrinsic disorder plus complementary electrostatics can significantly accelerate protein binding interactions. © 2012 American Chemical Society.

Terakawa T.,Kyoto University | Kenzaki H.,Kyoto University | Takada S.,Kyoto University | Takada S.,Japan Science and Technology Agency
Journal of the American Chemical Society | Year: 2012

The tumor suppressor p53 is a transcription factor that searches its cognate sites on DNA. During the search, the roles and interplay of its two DNA binding domains, the folded core domain and the disordered C-terminal domain (CTD), have been controversial. Here, we performed molecular simulations of p53 at various salt concentrations finding that, at physiological salt concentration, p53 diffuses along nonspecific DNA via rotation-uncoupled sliding with its CTD, whereas the core domain repeats dissociation and association. This is in perfect agreement with a recent single molecule experiment. In the simulation of tetrameric full-length p53, two DNA binding domains both bound to nonspecific DNA in a characteristic form at low salt concentration, whereas at physiological salt concentration, only CTD kept bound to DNA and the core domain frequently hopped on DNA. Simulations of a construct that lacks the core domain (TetCD) clarified rotation-uncoupled diffusion on nonspecific DNA. At low salt concentration, the diffusion constant due to sliding was dependent on the salt concentration, which differs from the prediction of a classic theory of transcription factors. At physiological salt concentration, it was independent of the salt concentration, in harmony with experiments. Moreover, we found that the sliding via the CTD follows the helical pitch of DNA (i.e., rotation-coupled sliding) at low salt concentration while it is virtually uncoupled to the helical pitch, a hallmark of rotation-uncoupled sliding at physiological salt concentration. © 2012 American Chemical Society.

Fujii S.,Kyoto University | Sato N.,Kyoto University | Shikanai T.,Kyoto University | Shikanai T.,Japan Science and Technology Agency
Plant Cell | Year: 2013

Pentatricopeptide repeat (PPR) proteins bind RNA and act in multiple eukaryotic processes, including RNA editing, RNA stability, and translation. Here, we investigated the mechanism underlying the functional versatility of Arabidopsis thaliana PROTON GRADIENT REGULATION3 (PGR3), a chloroplast protein harboring 27 PPR motifs. Previous studies suggested that PGR3 acts in (1) stabilization of photosynthetic electron transport L (petL) operon RNA, (2) translation of petL, and (3) translation of ndhA. We showed here that replacement of the 4th amino acid of the 12th PPR with nonpolar or charged amino acids abolished functions (1) and (2) but not (3) of PGR3 by compromising the function of this specific PPR. This discovery enabled us to knock out the RNA binding ability of individual PPR motifs. Consequently, we showed that the 16 N-terminal PPRs were sufficient for function (1) via sequence-specific RNA binding, whereas the 11 C-terminal motifs were essential for functions (2) and (3) by activating translation. We also clarified that the 14th amino acid of the 12th PPR should be positively charged to make the PPR functionally active. Our finding opens up the possibility of selectively manipulating the functions of PPR proteins. © American Society of Plant Biologists. All rights reserved.

Enami S.,Kyoto University | Enami S.,Japan Science and Technology Agency | Hoffmann M.R.,California Institute of Technology | Colussi A.J.,California Institute of Technology
Journal of Physical Chemistry Letters | Year: 2012

Unraveling the complex interactions between the atmosphere and the biosphere is critical for predicting climate changes. Although it is well-recognized that the large amounts of biogenic volatile organic compounds (BVOCs) emitted by plants must play important roles in this regard, current atmospheric models fail to account for their fate due to missing chemical sinks. Here, we applied online electrospray mass spectrometry to monitor aqueous microjets exposed to gaseous monoterpenes (α-pinene, β-pinene, and d-limonene) and found that these BVOCs are readily protonated (to C 10H 17 +) and undergo oligomerization (to C 20H 33 + and C 30H 49 +) upon colliding with the surface of pH < 4 microjets. By considering that the yields of all products show inflection points at pH ∼ 3.5 and display solvent kinetic hydrogen isotope effects larger than 2, we conclude that the oligomerization process is initiated by weakly hydrated hydronium ions, H 3O +, present at the gas-water interface. Present results provide a universal mechanism for the dry deposition of unsaturated BVOCs and may account for recent observations on the uptake of terpenes in forest canopies and over grassland. © 2012 American Chemical Society.

Hara S.,Yamanashi University | Irie H.,Yamanashi University | Irie H.,Japan Science and Technology Agency
Applied Catalysis B: Environmental | Year: 2012

We prepared two types of SrTiO 3-based photocatalyst powders, Bi,Ga-doped SrTiO 3 and In,V-doped SrTiO 3. UV-visible reflectance spectra of these powders indicated that their band-gaps remained constant in comparison with that of SrTiO 3. In conjunction with the reported band structure control of oxides, our results indicated that Bi,Ga-doped SrTiO 3 and In,V-doped SrTiO 3 formed isolated mini-bands composed of Bi 6s orbitals in the forbidden band above the valence band, composed of O 2p, and V 3d orbitals below the conduction band, composed of Ti 3d, resulting in the observed visible-light absorption. Utilizing the prepared SrTiO 3-based photocatalysts, we established a two-step overall water-splitting system, in which simultaneous liberation of hydrogen and oxygen with a molar ratio of ~2:1 was observed in the presence of I - (NaI) under irradiation with UV-containing light. Moreover, visible light contributed the cycling of I -/IO 3 - redox mediators, resulting in enhanced hydrogen and oxygen liberation when compared to irradiation with UV light alone. © 2012 Elsevier B.V..

Toyabe S.,Chuo University | Sagawa T.,University of Tokyo | Ueda M.,University of Tokyo | Ueda M.,Japan Science and Technology Agency | And 2 more authors.
Nature Physics | Year: 2010

In 1929, Leó Szilárd invented a feedback protocol1 in which a hypothetical intelligence-dubbed Maxwell's demon-pumps heat from an isothermal environment and transforms it into work. After a long-lasting and intense controversy it was finally clarified that the demon's role does not contradict the second law of thermodynamics, implying that we can, in principle, convert information to free energy2-6. An experimental demonstration of this information-to-energy conversion, however, has been elusive. Here we demonstrate that a non-equilibrium feedback manipulation of a Brownian particle on the basis of information about its location achieves a Szilárd-type information-to-energy conversion. Using real-time feedback control, the particle is made to climb up a spiral-staircase-like potential exerted by an electric field and gains free energy larger than the amount of work done on it. This enables us to verify the generalized Jarzynski equality7, and suggests a new fundamental principle of an 'information-to-heat engine' that converts information into energy by feedback control. © 2010 Macmillan Publishers Limited. All rights reserved.

Masuda N.,University of Tokyo | Masuda N.,Japan Science and Technology Agency
New Journal of Physics | Year: 2010

It is often useful to represent the infectious dynamics of mobile agents by metapopulation models. In such a model, metapopulations form a static network, and individuals migrate from one metapopulation to another. It is known that heterogeneous degree distributions of metapopulation networks decrease the epidemic threshold above which epidemic spreads can occur. We investigate the combined effect of heterogeneous degree distributions and diffusion on epidemics in metapopulation networks. We show that for arbitrary heterogeneous networks, diffusion suppresses epidemics in the sense of an increase in the epidemic threshold. On the other hand, some diffusion rates are needed to elicit epidemic spreads on a global scale. As a result of these opposing effects of diffusion, epidemic spreading near the epidemic threshold is most pronounced at an intermediate diffusion rate. The result that diffusion can suppress epidemics contrasts with that for diffusive SIS dynamics and its variants when individuals are fixed at nodes on static networks. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Takumi T.,Hiroshima University | Takumi T.,Japan Science and Technology Agency
Journal of Neurodevelopmental Disorders | Year: 2011

Autism is a neurodevelopmental disorder that manifests in childhood as social behavioral abnormalities, such as abnormal social interaction, impaired communication, and restricted interest or behavior. Of the known causes of autism, duplication of human chromosome 15q11-q13 is the most frequently associated cytogenetic abnormality. Chromosome 15q11-q13 is also known to include imprinting genes. In terms of neuroscience, it contains interesting genes such as Necdin, Ube3a, and a cluster of GABAA subunits as well as huge clusters of non-coding RNAs (small nucleolar RNAs, snoRNAs). Phenotypic analyses of mice genetically or chromosomally engineered for each gene or their clusters on a region of mouse chromosome seven syntenic to human 15q11-q13 indicate that this region may be involved in social behavior, serotonin metabolism, and weight control. Further studies using these models will provide important clues to the pathophysiology of autism. This review overviews phenotypes of mouse models of genes in 15q11-q13 and their relationships to autism. © 2011 Springer Science+Business Media, LLC.

Kusumi A.,Kyoto University | Suzuki K.G.N.,Kyoto University | Suzuki K.G.N.,Japan Science and Technology Agency | Kasai R.S.,Kyoto University | And 2 more authors.
Trends in Biochemical Sciences | Year: 2011

Based on recent single-molecule imaging results in the living cell plasma membrane, we propose a hierarchical architecture of three-tiered mesoscale (2-300. nm) domains to represent the fundamental functional organization of the plasma membrane: (i) membrane compartments of 40-300. nm in diameter due to the partitioning of the entire plasma membrane by the actin-based membrane skeleton 'fence' and transmembrane protein 'pickets' anchored to the fence; (ii) raft domains (2-20. nm); and (iii) dimers/oligomers and greater complexes of membrane-associated proteins (3-10. nm). The basic molecular interactions required for the signal transduction function of the plasma membrane can be fundamentally understood and conveniently summarized as the cooperative actions of these mesoscale domains, where thermal fluctuations/movements of molecules and weak cooperativity play crucial roles. © 2011 Elsevier Ltd.

Okamoto A.,RIKEN | Okamoto A.,Japan Science and Technology Agency
Chemical Record | Year: 2010

An excitonic interaction caused by the H-aggregation of fluorescent dyes is a new type of useful photophysical process for fluorescence-controlled nucleic acid sensing. We designed a fluorescence-labeled nucleotide in which two thiazole orange dyes were linked covalently. A DNA strand containing this fluorescence-labeled nucleotide showed absorption at 480 nm before hybrid- ization, whereas an absorption band at 510 nm became predominant when the DNA was hybridized with the complementary strand. The shift in the absorption bands shows the existence of an excitonic interaction between dyes in the nucleotide, and as a result, emission from the doubly thiazole orange- labeled DNA was well controlled. This clear change in fluorescence intensity depending on hybrid- ization is applicable to multicolor RNA imaging in living cells. © 2010 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

Ito T.,National University of Singapore | Ito T.,Japan Science and Technology Agency
Current Opinion in Plant Biology | Year: 2011

Floral homeotic genes encode transcription factors and act as master regulators of flower development. The homeotic protein complex is expressed in a specific whorl of the floral primordium and determines floral organ identity by the combinatorial action. Homeotic proteins continue to be expressed until late in flower development to coordinate growth and organogenesis. Recent genomic studies have shown that homeotic proteins bind thousands of target sites in the genome and regulate the expression of transcription factors, chromatin components and various proteins involved in hormone biosynthesis and signaling and other physiological activities. Further, homeotic proteins program chromatin to direct the developmental coordination of stem cell maintenance and differentiation in shaping floral organs. © 2010 Elsevier Ltd.

Hatano M.,Nagoya University | Horibe T.,Nagoya University | Ishihara K.,Nagoya University | Ishihara K.,Japan Science and Technology Agency
Journal of the American Chemical Society | Year: 2010

(Chemical Equation Presented) A highly diastereo- and enantioselective direct Mannich-type reaction of aldimines with 1,3-dicarbonyl compounds using Li(I) BINOLate salts as effective Lewis acid-Brønsted base catalysts has been developed. Li(I) BINOLate salts offered high catalytic activity toward 1,3-dicarbonyl compounds such as diketone, ketoester, ketothioester, ketoamide, and ketolactone. The reactions proceeded at -78 °C within 1-2 h in the presence of 1-10 mol % catalyst, which showed a catalytic activity (turnover frequency = 284 h-1) quite unlike those of other previous catalysts. Anti products were selectively obtained from acyclic ketoesters without epimerization at an α-3°-carbon center, and these are valuable since previous catalysts often gave syn/anti mixtures or the stereochemistry has not yet been determined. © 2010 American Chemical Society.

Ito H.,Hokkaido University | Ito H.,Japan Science and Technology Agency | Okura T.,Hokkaido University | Matsuura K.,Hokkaido University | Sawamura M.,Hokkaido University
Angewandte Chemie - International Edition | Year: 2010

(Figure prsented) Breaking the mirror: The reaction sequence described in the title was applied to the synthesis of a valuable chiral drug precursor and the rapid stereoselective assembly of complex compounds with multiple chiral centers (see scheme). © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

Yamamoto T.,Kyoto University | Yamada T.,Kyoto University | Nagata Y.,Kyoto University | Suginome M.,Kyoto University | Suginome M.,Japan Science and Technology Agency
Journal of the American Chemical Society | Year: 2010

A polyquinoxaline-based helical polymer ligand bearing both helical-sense-determining chiral side chains and coordinating diarylphosphino side chains exhibits solvent-dependent formation of P- or M-helical structures, with which either the S- or R-hydrosilylation product was obtained with high (>93% enantiomeric excess) enantioselectivities. © 2010 American Chemical Society.

Saze H.,National Institute of Genetics | Saze H.,Japan Science and Technology Agency | Kakutani T.,National Institute of Genetics
Current Opinion in Plant Biology | Year: 2011

Transposable elements (TEs) and repeats are methylated and silenced epigenetically in a variety of organisms including plants. Recent results in Arabidopsis suggest that the TE silencing can be reprogrammed by small RNA during gametogenesis. On the other hand, TE-specific DNA methylation independent of small RNA can be induced by H3K9 methylation through mechanisms conserved between plants and fungi. Methylation of CG sites is found not only in TEs but also in the body of constitutively transcribed genes. Although the function of gene-body methylation is still elusive, the distribution and control of this type of DNA methylation are very similar between plants and animals. Possible interactions of these multiple layers of epigenetic marks and their evolution are discussed. © 2010 Elsevier Ltd.

Nakanishi K.,Hyogo College of Medicine | Nakanishi K.,Japan Science and Technology Agency
Current Opinion in Immunology | Year: 2010

Basophils are important effector cells, which contribute to protection against helminths and execute proinflammatory effector function during allergic inflammation. Basophils are also regulators of Th2 responses in helminth-infected hosts and in allergen-injected animals. Recently, three groups using different experimental systems have shown that basophils are antigen-presenting cells (APC), which induce Th2 cells both in vitro and in vivo. Basophils express MHC class II and CD80/86, have the potential to take-up and process protein antigen (Ag), particularly Ag-IgE complexes, and to present peptide with MHC class II and produce IL-4. However, relevance of basophils as Th2 cell-inducing APC in vivo has been challenged by several recent reports that favor the concept that basophils and DC cooperate or basophils merely amplify DC-driven Th2 cell differentiation. In this review, I summarize and discuss the data on the role of basophils as Th2 cell-inducing APC in allergy and parasite infection. © 2010 Elsevier Ltd.

Morimoto M.,Rikkyo University | Morimoto M.,Japan Science and Technology Agency | Irie M.,Rikkyo University
Journal of the American Chemical Society | Year: 2010

The photomechancial effect of a rectangular plate two-component cocrystal composed of a photochromic diarylethene derivative, 1,2-bis(2-methyl-5-(1- naphthyl)-3-thienyl)perfluorocyclopentene (1o), and perfluoronaphthalene (FN) has been examined. The crystal of 1o•FN with the size of 1-5 mm in length exhibits reversible bending motion upon alternate irradiation with ultraviolet (UV) and visible light. The reversible bending could be repeated over 250 times. In situ X-ray crystallographic analysis revealed that the deformation of the crystal is due to the elongation of the b-axis of the unit cell, which corresponds to the long axis of the plate crystal, induced by the shape change of component diarylethene molecules upon photocyclization. The bending motion was observed even at 4.7 K, and dynamic measurement of the bending proved that the anisotropic expansion of the crystal takes place in the microsecond time scale at the low temperature. Molecular crystal cantilevers made of 1o•FN can lift metal balls, the weight of which is 200-600 times heavier than the weight of the crystal, upon UV irradiation. The maximum stress generated by UV irradiation was estimated to be 44 MPa, which is 100 times larger than that of muscles (∼0.3 MPa) and comparable to that of piezoelectric crystals, such as lead zirconate titanate (PZT) (∼50 MPa). © 2010 American Chemical Society.

Kobayashi M.,Kyushu University | Masaoka S.,Kyushu University | Masaoka S.,Japan Institute for Molecular Science | Masaoka S.,Japan Science and Technology Agency | Sakai K.,Kyushu University
Angewandte Chemie - International Edition | Year: 2012

Mimicking nature: The photochemical H 2 evolution from water catalyzed by a platinum(II)-based metalloviologen (PV 2+) proceeds via the photoexcited state of the one-electron-reduced species (PV + .; see picture, EDTA=ethylenediaminetetraacetic acid). This artificial photosynthesis is reminiscent of the "Z-scheme photosynthesis" in green plants. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kakiuchi F.,Keio University | Kochi T.,Keio University | Mizushima E.,Japan Science and Technology Agency | Murai S.,Nara Institute of Science and Technology
Journal of the American Chemical Society | Year: 2010

Mechanistic studies of the ruthenium-catalyzed reaction of aromatic ketones with olefins are presented. Treatment of the original catalyst, RuH 2(CO)(PPh3)3, with trimethylvinylsilane at 90 °C for 1-1.5 h afforded an activated ruthenium catalyst, Ru(o-C 6H4PPh2)(H)(CO)(PPh3)2, as a mixture of four geometric isomers. The activated complex showed high catalytic activity for C-H/olefin coupling, and the reaction of 2′-methylacetophenone with trimethylvinylsilane at room temperature for 48 h gave the corresponding ortho-alkylation product in 99% isolated yield. The activated catalyst was thermally robust and showed excellent catalytic activity under refluxing toluene conditions. 1H and 31P NMR studies of the C-H/olefin coupling at room temperature suggested that an ortho-ruthenated complex, P,P′-cis-C,H-cis-Ru(2′-(6′-MeC 6H4C(O)Me))(H)(CO)(PPh3)2, participated in the reaction as a key intermediate. Isotope labeling studies using acetophenone-d5 indicated that the rate-limiting step was the C-C bond formation, not the C-H bond cleavage, and that each step prior to the reductive elimination was reversible. The rate of C-H/olefin coupling was found to exhibit pseudo first-order kinetics and to show first-order dependence on the ruthenium complex concentration. © 2010 American Chemical Society.

Fujisawa J.-I.,Tokyo University of Science | Fujisawa J.-I.,Japan Science and Technology Agency | Giorgi G.,University of Tokyo
Physical Chemistry Chemical Physics | Year: 2014

Methylviologen lead-iodide perovskite (MVPb2I6) is a self-assembled one-dimensional (1-D) material consisting of lead-iodide nanowires and intervening organic electron-accepting molecules, methylviologen (MV2+). MVPb2I6 characteristically shows optical interfacial charge-transfer (ICT) transitions from the lead-iodide nanowire to MV2+ in the visible region and unique ambipolar photoconductivity, in which electrons are transported through the three-dimensional (3-D) organic network and holes along the 1-D lead-iodide nanowire. In this work, we theoretically study the electronic band-structure and photocarrier properties of MVPb2I6 by density functional theory (DFT) calculations. Our results clearly confirm the experimentally reported type-II band alignment, whose valence band mainly consists of 5p (I) orbitals of the lead-iodide nanowires and the conduction band of the lowest unoccupied molecular orbital of MV2+. The DFT calculation also reveals weak charge-transfer interactions between the lead-iodide nanowires and MV2+. In addition, the electronic distributions of the valence and conduction bands indicate the 3-D transport of electrons and 1-D transport of holes, supporting the reported experimental result. This journal is © the Partner Organisations 2014.

Teramura K.,Kyoto University | Teramura K.,Japan Science and Technology Agency | Iguchi S.,Kyoto University | Mizuno Y.,Kyoto University | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2012

Have a bit of bubbly: Significant amounts of CO and O 2 gas are evolved in the photocatalytic conversion of CO 2 over layered double hydroxides (LDHs) in water (see scheme). A simple mixture of the same metal hydroxides, which has the same constituent elements of the LDH, shows low activity for CO and O 2 evolution. Dissolved CO 2 gas was shown to be the source of carbon in the reaction over LDHs in water. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Yamazaki Y.,Japan Science and Technology Agency | Yamazaki Y.,California Institute of Technology | Blanc F.,University of Cambridge | Okuyama Y.,California Institute of Technology | And 5 more authors.
Nature Materials | Year: 2013

The environmental benefits of fuel cells have been increasingly appreciated in recent years. Among candidate electrolytes for solid-oxide fuel cells, yttrium-doped barium zirconate has garnered attention because of its high proton conductivity, particularly in the intermediate-temperature region targeted for cost-effective solid-oxide fuel cell operation, and its excellent chemical stability. However, fundamental questions surrounding the defect chemistry and macroscopic proton transport mechanism of this material remain, especially in regard to the possible role of proton trapping. Here we show, through a combined thermogravimetric and a.c. impedance study, that macroscopic proton transport in yttrium-doped barium zirconate is limited by proton-dopant association (proton trapping). Protons must overcome the association energy, 29 kJ mol -1, as well as the general activation energy, 16 kJ mol -1, to achieve long-range transport. Proton nuclear magnetic resonance studies show the presence of two types of proton environment above room temperature, reflecting differences in proton-dopant configurations. This insight motivates efforts to identify suitable alternative dopants with reduced association energies as a route to higher conductivities. © 2013 Macmillan Publishers Limited. All rights reserved.

Ando K.,Tohoku University | Ando K.,Keio University | Watanabe S.,University of Cambridge | Mooser S.,University of Cambridge | And 4 more authors.
Nature Materials | Year: 2013

Conjugated polymers and small organic molecules are enabling new, flexible, large-area, low-cost optoelectronic devices, such as organic light-emitting diodes, transistors and solar cells. Owing to their exceptionally long spin lifetimes, these carbon-based materials could also have an important impact on spintronics, where carrier spins play a key role in transmitting, processing and storing information. However, to exploit this potential, a method for direct conversion of spin information into an electric signal is indispensable. Here we show that a pure spin current can be produced in a solution-processed conducting polymer by pumping spins through a ferromagnetic resonance in an adjacent magnetic insulator, and that this generates an electric voltage across the polymer film. We demonstrate that the experimental characteristics of the generated voltage are consistent with it being generated through an inverse spin Hall effect in the conducting polymer. In contrast with inorganic materials, the conducting polymer exhibits coexistence of high spin-current to charge-current conversion efficiency and long spin lifetimes. Our discovery opens a route for a new generation of molecular-structure-engineered spintronic devices, which could lead to important advances in plastic spintronics. © 2013 Macmillan Publishers Limited. All rights reserved.

Information on energy consumption and carbon dioxide (CO 2) emissions from the iron and steel industry may become important to the assessment of energy saving and the design of emissions trading schemes. This paper focuses monitoring aspects, used two methods to calculate CO 2 emission, the European Union Emission Trading Scheme and a method developed by the Japanese Iron and Steel Federation, to investigate the effect of the accounting method on the assessment of energy saving by four model steel mills with different levels of energy efficiency. Depending on the calculation method used, the calculated energy savings and calculated CO 2 emissions for a given mill were found to differ from 5% to 15% and 4% to 14% respectively, simply by using different calculation methods. Methodologies that evaluate only CO 2 emission and track emissions by process may not fully account for energy saving efforts such as using waste heat, generating power using byproduct gases, and energy management efforts applied over the whole mill rather than on a single process. Points of concern in the iron and steel industry are identified in the areas of calculating energy saving, determining CO 2 emissions, and setting benchmarks. © 2012 Elsevier Ltd.

Yoshida H.,Osaka University | Matsusaki M.,Osaka University | Akashi M.,Osaka University | Akashi M.,Japan Science and Technology Agency
Advanced Functional Materials | Year: 2013

Blood capillaries are crucial for the biological evaluation of drug diffusion to target tissues, and the penetration of cancer cells or viruses. Since most capillaries have a bilayered structure consisting of a monolayer of endothelial cells (ECs) and surrounding smooth muscle cells (SMCs), the in vitro reconstruction of this bilayered structure is a key challenge for pharmaceutical and biomedical applications. Here, a unique technology to construct size, length, orientation, and layer-number controllable blood capillary networks in biodegradable hydrogels is reported. Uniaxial microchannels are prepared inside biodegradable hydrogels by the simple extraction of silica capillary tubes. The channel size, length, and distance of the uniaxial channels are easily controlled by altering these parameters of the silica tubes. The inner surfaces of the channels are successfully covered by bilayered structures consisting of ECs and SMCs by a hierarchical cell manipulation technique. Notably, serum albumin, which has an approximately 8 nm size, cannot penetrate this capillary wall during several hours of incubation due to the high blood vessel wall barrier property. This suggests a successful reconstruction of multilayered blood capillary networks possessing similar barrier function as native blood capillaries. Moreover, these capillary networks can be completely collected by the selective degradation of the surrounding hydrogels. This technique will be an innovative and versatile approach for in vitro permeability assays of drugs, drug delivery carriers, and cancer cells. Blood capillary networks consisting of bilayered structures of human endothelial cells and smooth muscle cells are prepared inside biodegradable hydrogels by a combination of uniaxial tubular microchannel fabrication and hierarchical cell manipulation. These blood capillary analogs, possessing blood barrier functions similar to native blood capillaries, can be useful for in vitro permeability assays of drugs and as drug delivery carriers. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Suemitsu M.,Tohoku University | Suemitsu M.,Japan Science and Technology Agency | Fukidome H.,Tohoku University
Journal of Physics D: Applied Physics | Year: 2010

By forming an ultrathin (∼100 nm) SiC film on Si substrates and by annealing it at ∼1500 K in vacuo, few-layer graphene is formed on Si substrates. Graphene grows on three major low-index surfaces: (1 1 1), (1 0 0) and (1 1 0), allowing us to tune its electronic properties by controlling the crystallographic orientation of the substrate. This graphene on silicon (GOS) technology thus paves the way to industrialization of this new material with inherent excellence. With its feasibility in Si technology, GOS is one of the most promising candidates as a material for Beyond CMOS technology. © 2010 IOP Publishing Ltd.

Horio M.,Japan Science and Technology Agency
Particuology | Year: 2010

By revisiting the three stage theory for the progress of science proposed by Taketani in 1942, the footmarks of fluidization research are examined. The bubbling and fast fluidization issues were emphasized so that the future of fluidization research can be discussed among scientists and engineers in a wider perspective. The first cycle of fluidization research was started in the early 1940s by an initial stage of phenomenology. The second stage of structural studies was kicked off in the early 1950s with the introduction of the two phase theory. The third stage of essential studies occurred in the early 1960s in the form of bubble hydrodynamics. The second cycle, which confirmed the aforementioned three stages closed at the turn of the century, established a general understanding of suspension structures including agglomerating fluidization, bubbling, turbulent and fast fluidizations and pneumatic transport; also established powerful measurement and numerical simulation tools.After a general remark on science, technology and society issues the interactions between fluidization technology and science are revisited. Our future directions are discussed including the tasks in the third cycle, particularly in its phenomenology stage where strong motivation and intention are always necessary, in relation also to the green reforming of the present technology. A generalized definition of 'fluidization' is proposed to extend fluidization principle into much wider scientific fields, which would be effective also for wider collaborations. © 2010 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences.

Okada M.,Osaka University | Okada M.,Japan Science and Technology Agency
Journal of Physics Condensed Matter | Year: 2010

I review our recent studies of chemical reactions on single-crystalline Cu and Si surfaces induced by hyperthermal oxygen molecular beams and by oriented molecular beams, respectively. Studies of oxide formation on Cu induced by hyperthermal molecular beams suggest that the translational energy of the incident molecules plays a significant role. The use of hyperthermal molecular beams enables us to open up new chemical reaction paths, and to develop new methods for the fabrication of thin films. Oriented molecular beams also demonstrate the possibility for controlling surface chemical reactions by varying the orientation of the incident molecules. The steric effects found on Si surfaces hint at new ways of achieving material fabrication on Si surfaces. Controlling the initial conditions of incoming molecules is a powerful tool for creating new materials on surfaces with well-controlled chemical reactions. © 2010 IOP Publishing Ltd.

Umeyama T.,Kyoto University | Umeyama T.,Japan Science and Technology Agency | Imahori H.,Kyoto University
Journal of Materials Chemistry A | Year: 2014

The polymer solar cell (PSC) technology has continued to be developed, and the power conversion efficiency (PCE) has now exceeded 10%. The rapid improvement of PCEs in the last decade has mainly resulted from versatile synthetic efforts for conjugated polymers as electron-donors and fullerene derivatives as electron-acceptors. This Feature Article highlights recent exploration of unique, attractive building blocks, i.e., quinoidal units, phospholes, porphyrins, and fluorinated aromatic rings, which can be incorporated into low bandgap conjugated polymers. As candidates for the next-generation acceptor materials that replace the benchmark acceptor, [6,6]-phenyl-C61-butyric acid methyl ester ([60]PCBM), fullerene bisadduct regioisomers are also overviewed. Furthermore, we summarized recent attempts for the construction of one-dimensionally confined, organic donor-acceptor heterojunction nanorods and their applications to photovoltaic and optoelectronic devices. The topics in this article are not intended to cover an exhaustive list of PSC research studies, but involve the fundamental aspect to stimulate further studies for getting new insights into the structure-property relationship in PSC devices. This journal is © the Partner Organisations 2014.

Tamesue S.,Osaka University | Takashima Y.,Osaka University | Yamaguchi H.,Osaka University | Shinkai S.,Japan Institute of Systems, Information Technologies and Nanotechnologies | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2010

Shine a light: A supramolecular hydrogel is formed by the glucan curdlan equipped with α-cyclodextrins (CD-CUR) and azobenzene-modified poly(acrylic acid)(pAC12Azo). The sol-gel transition and the morphology of the supramolecular hydrogel can be switched by photoirradiation at the appropriate wavelength, which controls the formation of an inclusion complex between the α-cyclodextrins and the azobenzene moieties (see picture). © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

Sugizaki K.,RIKEN | Okamoto A.,Japan Science and Technology Agency
Bioconjugate Chemistry | Year: 2010

Hybridization-sensitive fluorescent DNA probes containing the nucleotide units of locked nucleic acid (LNA) have been developed. Exciton-controlled hybridization-sensitive fluorescent oligonucleotide (ECHO) probes that incorporated LNA nucleotides achieved high thermostability of the hybrid with target RNA strands. The appropriately designed ECHO-LNA chimeric probes exhibited an effective on-off switching property of fluorescence depending on hybridization with RNA and facilitated fluorescent detection of the TAR RNA strand forming a hairpin structure and distinction of one base difference in PLAC4 RNA sequence. © 2010 American Chemical Society.

Ito H.,Hokkaido University | Ito H.,Japan Science and Technology Agency | Kunii S.,Hokkaido University | Sawamura M.,Hokkaido University
Nature Chemistry | Year: 2010

Asymmetric reactions that transform racemic mixtures into enantio-enriched products are in high demand, but classical kinetic resolution produces enantiopure compounds in <50% yield even in an ideal case. Many deracemization processes have thus been developed including dynamic kinetic resolution and dynamic kinetic asymmetric transformation, which can provide enantio-enriched products even after complete conversion of the racemic starting materials. However, these dynamic processes require racemization or symmetrization of the substrates or intermediates. We demonstrate a direct chemical enantio-convergent transformation without a racemization or symmetrization process. Copper(I)-catalysed asymmetric allylic substitution of a racemic allylic ether afforded a single enantiomer of an α-chiral allylboronate with complete conversion and high enantioselectivity (up to 98% enantiomeric excess). One enantiomer of the substrate undergoes an anti-S N 2-type reaction whereas the other enantiomer reacts via a syn-SN2 pathway. The products, which cannot be prepared by dynamic procedures, have been used to construct all-carbon quaternary stereocentres. © 2010 Macmillan Publishers Limited.

Nishimasu H.,University of Tokyo | Nishimasu H.,Japan Science and Technology Agency | Ran F.A.,The Broad Institute of MIT and Harvard | Ran F.A.,Massachusetts Institute of Technology | And 13 more authors.
Cell | Year: 2014

The CRISPR-associated endonuclease Cas9 can be targeted to specific genomic loci by single guide RNAs (sgRNAs). Here, we report the crystal structure of Streptococcus pyogenes Cas9 in complex with sgRNA and its target DNA at 2.5 Å resolution. The structure revealed a bilobed architecture composed of target recognition and nuclease lobes, accommodating the sgRNA:DNA heteroduplex in a positively charged groove at their interface. Whereas the recognition lobe is essential for binding sgRNA and DNA, the nuclease lobe contains the HNH and RuvC nuclease domains, which are properly positioned for cleavage of the complementary and noncomplementary strands of the target DNA, respectively. The nuclease lobe also contains a carboxyl-terminal domain responsible for the interaction with the protospacer adjacent motif (PAM). This high-resolution structure and accompanying functional analyses have revealed the molecular mechanism of RNA-guided DNA targeting by Cas9, thus paving the way for the rational design of new, versatile genome-editing technologies. © 2014 Elsevier Inc.

Tomioka K.,Hokkaido University | Tomioka K.,Japan Science and Technology Agency | Motohisa J.,Hokkaido University | Hara S.,Hokkaido University | And 2 more authors.
Nano Letters | Year: 2010

We report on integration of GaAs nanowire-based light-emitting-diodes (NW-LEDs) on Si substrate by selective-area metalorganic vapor phase epitaxy. The vertically aligned GaAs/AlGaAs core-multishell nanowires with radial p-n junction and NW-LED array were directly fabricated on Si. The threshold current for electroluminescence (EL) was 0.5 mA (current density was approximately 0.4 A/cm2), and the EL intensity superlinearly increased with increasing current injections indicating superluminescence behavior. The technology described in this letter could help open new possibilities for monolithic- and on-chip integration of III-V NWs on Si. © 2010 American Chemical Society.

Hatano M.,Nagoya University | Moriyama K.,Nagoya University | Maki T.,Nagoya University | Ishihara K.,Nagoya University | Ishihara K.,Japan Science and Technology Agency
Angewandte Chemie - International Edition | Year: 2010

(Figure Presented) Both catalysts work: A highly enantioselective direct Mannich-type reaction of NBoc-protected aldimines with 1,3-dicarbonyl compounds has been developed with the use of a chiral phosphoric acid in the presence or absence of Ca". The absolute stereoselectivity of the phosphoric acid catalysis was found to be opposite to that of the calcium phosphate catalysis (see scheme; Boc = tert-butoxycarbonyl). © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

Guo J.,Kyoto University | Ohkita H.,Kyoto University | Ohkita H.,Japan Science and Technology Agency | Benten H.,Kyoto University | Ito S.,Kyoto University
Journal of the American Chemical Society | Year: 2010

The charge generation and recombination dynamics in blend films of a poly(3-hexylthiophene) (P3HT) and a methanofullerene derivative (PCBM) were comprehensively studied by transient absorption spectroscopy in the wavelength region from 450 to 1650 nm under various excitation intensities and different excitation wavelengths. In homogeneously mixed blend films of regiorandom P3HT (RRa-P3HT) and PCBM, virtually all the excitons can reach the interface of RRa-P3HT/PCBM and then form bound radical pairs. However, two-thirds of them geminately recombine to the ground state, and only one-third of them can be dissociated into free polarons that survive up to milliseconds. In phase-separated blend films of regioregular P3HT (RR-P3HT) and PCBM, almost all the excitons can reach the interface of RR-P3HT/PCBM, where most of them can be dissociated into free polarons efficiently and the rest of them form bound radical pairs. There are two pathways for the polaron generation: the prompt formation from hot excitons generated near the interface on a time scale of <100 fs and the delayed formation via the exciton migration to the interface on a time scale of ∼10 ps. The thermal annealing improves the charge dissociation efficiency of bound radical pairs. On the basis of such spectroscopic data, a series of fundamental photovoltaic conversion processes are quantitatively analyzed. Consequently, it is concluded that there is not much difference in the charge generation yield between RRa-P3HT/PCBM(50 wt %) and RR-P3HT/PCBM(50 wt %) blend films. Rather, the charge dissociation and collection have a critical impact on the overall device performance of P3HT/PCBM solar cells, where the phase-separated blend structures have a high tendency to form free carriers and transport these free carriers to the electrode. © 2010 American Chemical Society.

Bandyopadhyay A.,Japan Science and Technology Agency | Higuchi M.,Japan National Institute of Materials Science
European Polymer Journal | Year: 2013

Co(III)- and Fe(III)-based metallosupramolecular polymers with aromatic azo ligands were synthesized via polycondensation of the diamino-substituted metal complexes with aromatic dialdehydes. Three different amino-substituted Co(III)-complexes were prepared through CN fusion reaction of [Co(pap) 3](ClO4)2 with 1,4-phenylenediamine. All Co(III)- and Fe(III)-monomers and the metallosupramolecular polymers and a Co(III)-dimer were characterized by NMR, MS and UV-vis spectroscopy. Both the Co(III)- and Fe(III)-based metallosupramolecular polymers were electrochemically active and exhibited reversible electrochromism. The color of the Co(III)-based metallosupramolecular polymer could be changed upon application of an appropriate potential and regenerated upon reversal of the potential. © 2013 Elsevier B.V. All rights reserved.

Miyoshi T.,Keio University | Takeuchi A.,Keio University | Siomi H.,Keio University | Siomi M.C.,Keio University | Siomi M.C.,Japan Science and Technology Agency
Nature Structural and Molecular Biology | Year: 2010

Heat-shock proteins (Hsps) are molecular chaperones that control protein folding and function. Argonaute 2 (Ago2), the effector in RNA interference (RNAi), is associated with Hsp90; however, its function in RNAi remains elusive. Here we show that Hsp90 is required for Ago2 to receive the small interfering RNA (siRNA) duplex from the RNA-induced silencing complexĝ€" loading complex in RNAi, suggesting a model where Hsp90 modifies Ago2 conformation to accommodate the siRNA duplex. © 2010 Nature America, Inc. All rights reserved.

Oka H.,Japan Science and Technology Agency | Oka H.,Osaka University
Optics Express | Year: 2010

We theoretically investigate the sequential two-step upconversion of correlated photon pairs with positive and negative energy correlations, in terms of how the up-conversion efficiency depends on the incident pulse delay. A three-level atomic system having a metastable state is used to evaluate the up-conversion efficiency. It is shown that a photon pair with a positive energy correlation can drastically enhance the up-conversion efficiency compared with uncorrelated photons and correlated photons with a negative energy correlation. © 2010 Optical Society of America.

Nagata S.,Kyoto University | Nagata S.,Japan Science and Technology Agency
Annals of the New York Academy of Sciences | Year: 2010

Every day billions of cells die in our bodies to eliminate those that are harmful, useless, or senescent. The process can be divided into two steps: cell dying and cell clearance. In the first step, death machinery is activated in the cells and quickly kills them. During the second step, dead cells are engulfed by phagocytes, and their components are degraded in the lysosomes of the phagocytes. The death mechanism and the clearance of dead cells have been extensively studied. Mouse lines that are deficient in the death or clearance process have been established, and human patients carrying a mutation in the death machinery have been identified. Data from these mutant mice and human patients indicate that defects in cell death or dead-cell clearance leads to autoimmunity. This review examines the cell death and clearance processes and briefly discusses the diseases they cause. © 2010 New York Academy of Sciences.

Kinugasa Y.,Osaka University | Matsui T.,Osaka University | Takakura N.,Osaka University | Takakura N.,Japan Science and Technology Agency
Stem Cells | Year: 2014

Cells constituting the tumor microenvironment are attractive targets for developing new cancer therapies. Here we show that cancer-associated fibroblasts (CAFs) support tumor growth in vivo and maintain the stemness of cancer stem/initiating cells in an in vitro model using an established CAF cell line. We found that CD44 is abundantly expressed on CAFs. This molecule is a cancer stem cell marker in several tumors, but its role in tumorigenesis when expressed by CAFs has not been investigated. It is generally accepted that hypoxic and hyponutritional conditions are triggers of cancer malignancy. We found that CAFs strongly express CD44 in hypoxic and avascular areas in the tumor and that its expression on established CAFs is upregulated under hypoxic and hyponutritional conditions in vitro. In addition, CAF CD44-positivity in tumor tissues was increased after treatment with inhibitors of angiogenesis. Using cocultures and tumor sphere formation assays, CAFs from wild-type mice were found to sustain the stemness of cancer stem/initiating cells, while CD44-deficient CAFs did not. Furthermore, CD44 was involved in malignant cancer cell drug resistance mechanisms. In conclusion, our study suggests that CD44 on CAFs is a functional molecule contributing to the maintenance of cancer stem cell populations in the tumor microenvironment.© AlphaMed Press 2013.

Ohtsu H.,Japan Institute for Molecular Science | Ohtsu H.,Japan Science and Technology Agency | Tanaka K.,Japan Institute for Molecular Science | Tanaka K.,Kyoto University
Angewandte Chemie - International Edition | Year: 2012

Ruthenium will fix it: CO 2 undergoes reduction to HCO 2 - when placed over a solution of a ruthenium complex bearing an NADH model ligand 1 (black in right structural formula). The organic hydride transfer is triggered by the addition of benzoate anion, which rapidly forms a complex with 1, a complex that is a stronger reductant than 1. A photocatalytic variant of the reaction using triethanolamine as a sacrificial reagent has also been developed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mansai S.P.,Graduate University for Advanced Studies | Innan H.,Graduate University for Advanced Studies | Innan H.,Japan Science and Technology Agency
Genetics | Year: 2010

Interlocus gene conversion can homogenize DNA sequences of duplicated regions with high homology. Such nonvertical events sometimes cause a misleading evolutionary interpretation of data when the effect of gene conversion is ignored. To avoid this problem, it is crucial to test the data for the presence of gene conversion. Here, we performed extensive simulations to compare four major methods to detect gene conversion. One might expect that the power increases with increase of the gene conversion rate. However, we found this is true for only two methods. For the other two, limited power is expected when gene conversion is too frequent. We suggest using multiple methods to minimize the chance of missing the footprint of gene conversion. Copyright © 2010 by the Genetics Society of America.

Eda G.,Imperial College London | Eda G.,National University of Singapore | Yamaguchi H.,Rutgers University | Voiry D.,Rutgers University | And 4 more authors.
Nano Letters | Year: 2011

A two-dimensional crystal of molybdenum disulfide (MoS 2) monolayer is a photoluminescent direct gap semiconductor in striking contrast to its bulk counterpart. Exfoliation of bulk MoS 2 via Li intercalation is an attractive route to large-scale synthesis of monolayer crystals. However, this method results in loss of pristine semiconducting properties of MoS 2 due to structural changes that occur during Li intercalation. Here, we report structural and electronic properties of chemically exfoliated MoS 2. The metastable metallic phase that emerges from Li intercalation was found to dominate the properties of as-exfoliated material, but mild annealing leads to gradual restoration of the semiconducting phase. Above an annealing temperature of 300 °C, chemically exfoliated MoS 2 exhibit prominent band gap photoluminescence, similar to mechanically exfoliated monolayers, indicating that their semiconducting properties are largely restored. © 2011 American Chemical Society.

Mori T.,University of Tokyo | Mori T.,Japan Science and Technology Agency
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

Relationships between general long-range interacting classical systems on a lattice and the corresponding mean-field models (infinitely long-range interacting models) are investigated. We study systems in arbitrary dimension d for periodic boundary conditions and focus on the free energy for fixed value of the total magnetization. As a result, it is shown that the equilibrium free energy of the long-range interacting systems are exactly the same as that of the corresponding mean-field models (exactness of the mean-field theory). Moreover, the mean-field metastable states can be also preserved in general long-range interacting systems. It is found that in the case that the magnetization is conserved, the mean-field theory does not give correct property in some parameter region. © 2010 The American Physical Society.

Sakaue T.,Kyushu University | Sakaue T.,Japan Science and Technology Agency
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

Flexible polymers such as long DNA, RNA molecules, and proteins, can pass through a narrow pore whose size is comparable to their molecular thickness. We highlight the richness and complexity involved in the dynamics of this unique mode of molecular transport, called translocation, actively driven by external forces. In particular, the process takes place in the condition far from equilibrium accompanying of large conformational distortion in line with the propagation of the tensile force along the chain backbone. A general framework is proposed, which captures such essential features, whereby can account for reported various experimental data from a unified viewpoint. © 2010 The American Physical Society.

Chatterjee M.,Japan National Institute of Advanced Industrial Science and Technology | Ishizaka T.,Japan National Institute of Advanced Industrial Science and Technology | Kawanami H.,Japan National Institute of Advanced Industrial Science and Technology | Kawanami H.,Japan Science and Technology Agency
Green Chemistry | Year: 2014

The use of supercritical carbon dioxide-water on the hydrogenation of 5-hydroxymethylfurfural (HMF) was investigated over a Pd/C catalyst. It was possible to achieve a very high yield (100%) of DMF within the reaction time of 2 hours at 80 °C. A significant effect of CO2 pressure was observed on the product distribution. Simply by tuning the CO2 pressure it was possible to achieve various key compound, such as tetrahydro-5-methyl-2-furanmethanol (MTHFM) (<10 MPa), 2,5-dimethylfuran (DMF) (10 MPa) and 2,5-dimethyltetrahydrofuran (DMTHF) (>10 MPa) with very high selectivity. Optimization of other reaction parameters revealed that H 2 pressure, temperature, as well as the CO2-water mole ratio, played an important role in the selectivity to the targeted DMF. It is interesting to note that a very high yield of DMF was achieved when a combination of CO2 and water was used. For instance, in the absence of water or CO2, the selectivity of DMF was low; similarly, an excess of water against the fixed pressure of CO2 reduced the selectivity to DMF. Hence, an optimized amount of water was mandatory in the presence of CO2 for the formation of DMF with high selectivity. This method was successfully extended to the hydrogenation of furfural, which could afford 100% selectivity to 2-methylfuran with complete conversion within a very short reaction time of 10 min. The studied catalyst could be recycled successfully without significant loss of catalytic activity. © 2014 The Royal Society of Chemistry.

Chen L.,Japan Institute for Molecular Science | Yang Y.,Japan Institute for Molecular Science | Guo Z.,Japan Institute for Molecular Science | Jiang D.,Japan Science and Technology Agency
Advanced Materials | Year: 2011

A nanoporous metalloporphyrin framework exhibits high activity in the activation of molecular oxygen and excellent catalytic activity in the aerobic epoxidation of olefins, with high conversion, outstanding selectivity, and broad substrate applicability. The porous framework is reusable and allows large-scale transformation. These catalytic features are correlated with the structural characteristics of the porous framework and mark a breakthrough for this classic reaction. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nishiguchi A.,Osaka University | Yoshida H.,Osaka University | Matsusaki M.,Osaka University | Matsusaki M.,Japan Science and Technology Agency | Akashi M.,Osaka University
Advanced Materials | Year: 2011

A novel cell-accumulation technique has been developed using highly biocompatible nanofilms by layer-by-layer assembly for the rapid construction of thick layered tissues with a well-controlled layer number and thickness. Furthermore, 3D tissues with highly developed blood capillary networks (over 1 cm 2 of layered tissues) were also constructed by sandwiching endothelial cells between the layered tissues. Such a simple and rapid methodology would be useful for tissue engineering and drug assessment. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Furumi S.,Japan National Institute of Materials Science | Furumi S.,Japan Science and Technology Agency | Kanai T.,Yokohama National University | Sawada T.,Japan National Institute of Materials Science
Advanced Materials | Year: 2011

Widely tunable laser action by low threshold optical excitation can be realized by a colloidal crystal gel (CC-G) film permanently stabilized by a non-volatile ionic liquid. The CC-G film consists of a non-close-packed structure of microparticles immobilized in a polymer gel. Optical excitation with green light gives rise to a single and very narrow laser emission with red color. The single laser emission peak can be tuned in a wide wavelength range by applying mechanical stress. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nakagawa H.,Nagoya City University | Nakagawa H.,Japan Science and Technology Agency
Nitric Oxide - Biology and Chemistry | Year: 2011

Nitric oxide (NO) and nitroxyl (HNO) are small-molecular, unstable compounds that mediate a variety of biological effects, especially in the cardiovascular system. Because of the instability of NO and HNO, controlled release for experimental investigation of their activities requires the use of appropriate donor molecules. Early donors released these molecules via spontaneous decomposition, but more recently, NO and HNO donors which can be controlled by photoirradiation have been developed; these are far superior, allowing precise spatial and temporal control of NO and HNO release. Among photocontrollable NO donors, metal nitrosyl complexes and nitroarene compounds are very important; the former releases NO by photoinduced cleavage of the metal-NO bond, and the latter, by photoisomerization of the aryl nitro group. Only a few photocontrollable HNO donors are available so far, and these are based on retro hetero Diels-Alder reaction initiated by photoabsorption. This review of photocontrollable NO and HNO donors and their mechanisms also covers spontaneous-release donors to the extent necessary to understand their contribution to the development of the photocontrollable donors. © 2010 Published by Elsevier Inc.

Michinobu T.,Tokyo Institute of Technology | Michinobu T.,Japan Science and Technology Agency
Pure and Applied Chemistry | Year: 2010

A high-yielding addition reaction between electron-rich alkynes and a small acceptor molecule, tetracyanoethylene (TCNE), was employed as a new click reaction to construct donor-acceptor chromophores in the polymer main chains and side chains. The donor-acceptor alternating conjugated polymers were prepared from the ferrocenecontaining poly(aryleneethynylene)s in one step and atom-economic fashion. The energy levels and thermal properties of the aromatic polyamines substituted by electron-rich alkynes as a side chain can be tunable by the amount of the added TCNE. The resulting donor-acceptor-type polymers feature broad charge-transfer (CT) bands in the visible region, potent redox activities, and improved thermal properties. © 2010 IUPAC.

Suzuki Y.,Tohoku University | Makino A.,Tohoku University | Makino A.,Japan Science and Technology Agency
Plant Physiology | Year: 2012

Rubisco is composed of eight small subunits coded for by the nuclear RBCS multigene family and eight large subunits coded for by the rbcL gene in the plastome. For synthesis of the Rubisco holoenzyme, both genes ne