Budisantoso T.,National Institute for Physiological science |
Budisantoso T.,Graduate University for Advanced Studies |
Harada H.,National Institute for Physiological science |
Kamasawa N.,National Institute for Physiological science |
And 9 more authors.
Journal of Physiology | Year: 2013
Establishing the spatiotemporal concentration profile of neurotransmitter following synaptic vesicular release is essential for our understanding of inter-neuronal communication. Such profile is a determinant of synaptic strength, short-term plasticity and inter-synaptic crosstalk. Synaptically released glutamate has been suggested to reach a few millimolar in concentration and last for <1 ms. The synaptic cleft is often conceived as a single concentration compartment, whereas a huge gradient likely exists. Modelling studies have attempted to describe this gradient, but two key parameters, the number of glutamate in a vesicle (NGlu) and its diffusion coefficient (DGlu) in the extracellular space, remained unresolved. To determine this profile, the rat calyx of Held synapse at postnatal day 12-16 was studied where diffusion of glutamate occurs two-dimensionally and where quantification of AMPA receptor distribution on individual postsynaptic specialization on medial nucleus of the trapezoid body principal cells is possible using SDS-digested freeze-fracture replica labelling. To assess the performance of these receptors as glutamate sensors, a kinetic model of the receptors was constructed from outside-out patch recordings. From here, we simulated synaptic responses and compared them with the EPSC recordings. Combinations of NGlu and DGlu with an optimum of 7000 and 0.3 μm2 ms-1 reproduced the data, suggesting slow diffusion. Further simulations showed that a single vesicle does not saturate the synaptic receptors, and that glutamate spillover does not affect the conductance amplitude at this synapse. Using the estimated profile, we also evaluated how the number of multiple vesicle releases at individual active zones affects the amplitude of postsynaptic signals. © 2012 The Physiological Society.
Song C.,Leiden University |
Song C.,University of Leipzig |
Velazquez Escobar F.,TU Berlin |
Xu X.-L.,Max Planck Institute For Chemische Energiekonversion |
And 9 more authors.
Biochemistry | Year: 2015
The second GAF domain of AnPixJ, AnPixJg2, a bilin-binding protein from the cyanobacterium Anabaena PCC 7120, undergoes a photoinduced interconversion between a red-absorbing state, Pr, and a green-absorbing state, Pg. Combining ultraviolet-vis (UV-vis), infrared, resonance Raman (RR), and magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, we have studied this cyanobacteriochrome (CBCR) assembled with phycocyanobilin (PCB) either in vivo or in vitro. In both assembly routes, the spectroscopic data of the Pr state reveal nearly identical chromophore structures with a protonated (cationic) bilin. However, unlike the native (in vivo assembly) Pg photoproduct, in which the bilin retains protonation, the Pg generated from the in vitro-assembled AnPixJg2 harbors a deprotonated (neutral) bilin chromophore at pH 7.8. IR difference spectroscopy further reveals the transfer of a proton from the bilin to a side-chain carboxylate on an amino acid, probably Asp291. Besides the change in protonation state, the bilin structure is very similar in the in vitro- and in vivo-assembled Pg photoproducts. The chromophore of the in vitro Pg becomes protonated when the pH is increased to 10, presumably because of a partial reversal of protein misfolding. Most remarkably, the electronic transitions remain unchanged and are very similar to those of the native Pg. Thus, bilin protonation is not a key parameter for controlling the energies of the electronic transitions in AnPixJg2. Possible alternative molecular mechanisms for color tuning are discussed. © 2015 American Chemical Society.
Komanoya T.,Materials and Structures Laboratory |
Komanoya T.,Frontier Research Center |
Nakajima K.,Materials and Structures Laboratory |
Nakajima K.,Precursory Research for Embryonic Science and Technology PRESTO |
And 4 more authors.
Journal of Physical Chemistry C | Year: 2015
Early transition metal oxides, TiO2, ZrO2, and Nb2O5, were studied as heterogeneous catalysts for the Meerwein-Ponndorf-Verley (MPV) reduction of cyclohexanone in 2-propanol. Despite a small amount of Lewis acid sites and weak Lewis acid strength, ZrO2 was clearly superior to TiO2 and Nb2O5 with respect to reaction rate. Fourier transform infrared spectroscopy (FT-IR) and temperature-programmed-desorption (TPD) measurements revealed that ZrO2 has large amounts of base sites that activate the methylene groups in 2-propanol bonded to Lewis acid sites. Various analyses, including experiments using isotopic 2-propanol, suggest that efficient MPV reduction over ZrO2 is due not only to Lewis acid strength and density, but also to a synergistic effect of base and Lewis acid sites. © 2015 American Chemical Society.
Yamada M.,Japan National Institute of Radiological Sciences |
Yamada M.,Precursory Research for Embryonic Science and Technology PRESTO
Brain and Nerve | Year: 2014
The majority of individuals evaluate themselves as above average. This is a cognitive bias called "the superiority illusion". This illusory self-evaluation helps us to have hopes for the future, and has been central to the process of human evolution. Possessing this illusion is also important for mental health, as depressed people appear to have a more realistic perception of themselves, dubbed "depressive realism". Our recent study revealed the spontaneous brain activity and central dopaminergic neurotransmission that generate this illusion, using resting-state fMRI and PET. A functional connectivity between the frontal cortex and striatum, regulated by inhibitory dopaminergic neurotransmission, determines individual levels of the superiority illusion. We further revealed that blocking the dopamine transporter, which enhanced the level of dopamine, increased the degree of the superiority illusion. These findings suggest that dopamine acts on striatal dopamine receptors to suppress fronto-striatal functional connectivity, leading to disinhibited, heuristic, approaches to positive self-evaluation. These findings help us to understand how this key aspect of the human mind is biologically determined, and will suggest treatments for depressive symptoms by targeting specific molecules and neural circuits.
Yamori W.,University of Tokyo |
Yamori W.,Precursory Research for Embryonic Science and Technology PRESTO |
Shikanai T.,Japan Science and Technology Agency |
Shikanai T.,Kyoto University
Annual Review of Plant Biology | Year: 2016
The light reactions in photosynthesis drive both linear and cyclic electron transport around photosystem I (PSI). Linear electron transport generates both ATP and NADPH, whereas PSI cyclic electron transport produces ATP without producing NADPH. PSI cyclic electron transport is thought to be essential for balancing the ATP-NADPH production ratio and for protecting both photosystems from damage caused by stromal overreduction. Two distinct pathways of cyclic electron transport have been proposed in angiosperms: a major pathway that depends on the PROTON GRADIENT REGULATION 5 (PGR5) and PGR5-LIKE PHOTOSYNTHETIC PHENOTYPE 1 (PGRL1) proteins, which are the target site of antimycin A, and a minor pathway mediated by the chloroplast NADH dehydrogenase-like (NDH) complex. Recently, the regulation of PSI cyclic electron transport has been recognized as essential for photosynthesis and plant growth. In this review, we summarize the possible functions and importance of the two pathways of PSI cyclic electron transport. Copyright © 2016 by Annual Reviews. All rights reserved.
Wang Z.,Kyoto University |
Teramura K.,Kyoto University |
Teramura K.,Precursory Research for Embryonic Science and Technology PRESTO |
Teramura K.,Japan Science and Technology Agency |
And 4 more authors.
Catalysis Science and Technology | Year: 2016
Stoichiometric evolutions of CO, H2, and O2 were achieved for the photocatalytic conversion of CO2 with H2O as an electron donor using Ag-loaded Zn-modified Ga2O3. The selectivity toward the evolution of CO over H2 can be controlled by varying the amount of Zn species added in the Ag-loaded Zn-modified Ga2O3 photocatalyst. The production of H2 gradually decreased with increasing amounts of Zn species from 0.1 to 10.0 mol%, whereas the evolution of CO was almost unchanged. The XRD, XAFS, and XPS measurements revealed that a ZnGa2O4 layer was generated on the surface of Ga2O3 by modification with Zn species. The formation of the ZnGa2O4 layer eliminated the proton reduction sites on Ga2O3, although the crystallinity, surface area, and morphology of Ga2O3 as well as the particle size and chemical state of Ag did not change. In conclusion, we designed a highly selective photocatalyst for the conversion of CO2 with H2O as an electron donor using Ag (the cocatalyst for the CO evolution), ZnGa2O4 (the inhibitor of the H2 production), and Ga2O3 (the photocatalyst). © The Royal Society of Chemistry 2016.
Terashima A.,University of Tokyo |
Okamoto K.,University of Tokyo |
Nakashima T.,Tokyo Medical and Dental University |
Nakashima T.,Precursory Research for Embryonic Science and Technology PRESTO |
And 4 more authors.
Immunity | Year: 2016
Sepsis is a host inflammatory response to severe infection associated with high mortality that is caused by lymphopenia-associated immunodeficiency. However, it is unknown how lymphopenia persists after the accelerated lymphocyte apoptosis subsides. Here we show that sepsis rapidly ablated osteoblasts, which reduced the number of common lymphoid progenitors (CLPs). Osteoblast ablation or inducible deletion of interleukin-7 (IL-7) in osteoblasts recapitulated the lymphopenic phenotype together with a lower CLP number without affecting hematopoietic stem cells (HSCs). Pharmacological activation of osteoblasts improved sepsis-induced lymphopenia. This study demonstrates a reciprocal interaction between the immune and bone systems, in which acute inflammation induces a defect in bone cells resulting in lymphopenia-associated immunodeficiency, indicating that bone cells comprise a therapeutic target in certain life-threatening immune reactions. Much has been done on the identification of HSC niche, but the role of osteoblasts in hematopoiesis is unknown in acute immune responses. Takayanagi and colleagues show that sepsis reduces the osteoblast number, which induces lymphopenia through IL-7 downregulation, demonstrating a reciprocal interaction between the immune and bone systems. © 2016 Elsevier Inc.
Hara M.,Tokyo Institute of Technology |
Hara M.,Japan Science and Technology Agency |
Nakajima K.,Tokyo Institute of Technology |
Nakajima K.,Precursory Research for Embryonic Science and Technology PRESTO |
Kamata K.,Tokyo Institute of Technology
Science and Technology of Advanced Materials | Year: 2015
In recent decades, the substitution of non-renewable fossil resources by renewable biomass as a sustainable feedstock has been extensively investigated for the manufacture of high value-added products such as biofuels, commodity chemicals, and new bio-based materials such as bioplastics. Numerous solid catalyst systems for the effective conversion of biomass feedstocks into value-added chemicals and fuels have been developed. Solid catalysts are classified into four main groups with respect to their structures and substrate activation properties: (a) micro- and mesoporous materials, (b) metal oxides, (c) supported metal catalysts, and (d) sulfonated polymers. This review article focuses on the activation of substrates and/or reagents on the basis of groups (a)-(d), and the corresponding reaction mechanisms. In addition, recent progress in chemocatalytic processes for the production of five industrially important products (5-hydroxymethylfurfural, lactic acid, glyceraldehyde, 1,3-dihydroxyacetone, and furan-2,5-dicarboxylic acid) as bio-based plastic monomers and their intermediates is comprehensively summarized. © 2015 National Institute for Materials Science.
Shichita T.,Keio University |
Shichita T.,Precursory Research for Embryonic Science and Technology PRESTO |
Yoshimura A.,Keio University
Clinical and Experimental Neuroimmunology | Year: 2016
Inflammation is implicated in the pathogenesis of various central nervous system diseases. The brain is a sterile organ; therefore, inflammation is triggered by endogenous molecules. Pattern recognition receptors recognize specific endogenous molecules, and activate resident glial cells and peripheral immune cells. Inflammasome complex formation is also important for neuroinflammation in brain tissue injury, epilepsy and neurodegenerative diseases. Although inflammation exaggerates the pathology and neurological deficits in neurological disorders, triggering the pro-resolution process and neuronal repair is a beneficial side of inflammation. We introduce recent accumulating evidence about the relationship between neuroinflammation by innate immunity and the process of pathogenesis in central nervous system diseases. Inflammation is implicated in the pathogenesis of various central nervous system (CNS) diseases. Pattern recognition receptors recognize specific endogenous molecules and activate resident glial cells and peripheral immune cells. Inflammation exaggerates the pathology and neurological deficits in neurological disorders; while, triggering the pro-resolution process and neuronal repair is a beneficial side of inflammation © 2016 Japanese Society for Neuroimmunology.
Higo N.,Japan National Institute of Advanced Industrial Science and Technology |
Higo N.,Precursory Research for Embryonic Science and Technology PRESTO |
Kunori N.,Japan National Institute of Advanced Industrial Science and Technology |
Kunori N.,University of Tsukuba |
Murata Y.,Japan National Institute of Advanced Industrial Science and Technology
PLoS ONE | Year: 2016
In order to accurately interpret experimental data using the topographic body map identified by conventional intracortical microstimulation (ICMS), it is important to know how neurons in each division of the map respond during voluntary movements. Here we systematically investigated neuronal responses in each body representation of the ICMS map during a reach-grasp-retrieval task that involves the movements of multiple body parts. The topographic body map in the primary motor cortex (M1) generally corresponds to functional divisions of voluntary movements; neurons at the recording sites in each body representation with movement thresholds of 10μA or less were differentially activated during the task, and the timing of responses was consistent with the movements of the body part represented. Moreover, neurons in the digit representation responded differently for the different types of grasping. In addition, the present study showed that neural activity depends on the ICMS current threshold required to elicit body movements and the location of the recording on the cortical surface. In the ventral premotor cortex (PMv), no correlation was found between the response properties of neurons and the body representation in the ICMS map. Neural responses specific to forelimb movements were often observed in the rostral part of PMv, including the lateral bank of the lower arcuate limb, in which ICMS up to 100 μA evoked no detectable movement. These results indicate that the physiological significance of the ICMS-derived maps is different between, and even within, areas M1 and PMv. © 2016 Higo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.