News Article | April 17, 2017
Correlation between cryo-transmission electron microscope (TEM) images and the crystal structure. a) TEM image showing three colliding clusters. The scale bar is 10 nm. b) Relative positions of molecules derived from the X-ray diffraction crystal structure are overlaid (brown) on the TEM image. A twinning plane is shown (green line) Credit: Weizmann Institute of Science Crystallization is a very basic chemical process: School children can witness it with their own eyes. But scientists had not, until now, been able to observe this process on the molecular level - that is, the instant in which molecules overcome their tendencies to float individually in a liquid solution and take their place in the rigid lattice of a solid crystal structure. Researchers at the Weizmann Institute of Science have, for the first time, directly observed the process of crystallization on the molecular level, validating some recent theories about crystallization, as well as showing that if one knows how the crystal starts growing, one can predict the end structure. The research took place in the lab of Prof. Ronny Neumann of the Weizmann Institute's Organic Chemistry Department. Neumann explains that in order to bond to one another, the molecules must overcome an energy barrier: "The prevalent theory had been that chance contacts between molecules leads to bonding, eventually creating small clusters that become nuclei for larger crystals to grow. But the molecules, which move randomly in solution, must be aligned properly to crystalize. In recent years researchers have begun to think that this process might present too high an energy barrier." Theories proposed in the past few decades suggest that if the molecules were to congregate together in a so-called dense phase, in which they aggregate into a sardine-like state - close together but unorganized - and then crystallize from this state, the energy barrier would be lower.To test the theories, Neumann and PhD student Roy Schreiber created large, rigid molecules and froze them in place in solution. They then placed the frozen solution under an electron microscope beam that warmed up the mixture just enough to allow some movement, and thus interactions between the molecules. Adjusting the makeup of the solution by adding different ions enabled the scientists to produce crystallization with and without dense phases; for the first time, aided by Drs. Lothar Houben and Sharon Wolf of the Electron Microscopy Unit, they were able to observe dense phases forming and subsequently transforming into crystal nuclei. While both states yielded crystals, the experimental results showed that when dense phases form, the energy barrier to formation of an orderly, crystalline arrangement of molecules is, as the theory predicted, lower. The scientists also found that the growth arising from dense phases results in larger, more stable crystal nuclei. In addition they discovered that the arrangement of molecules in fully grown crystals, which they determined by X-ray crystallography with the aid of Dr. Gregory Leitus of Chemical Research Support, was in good agreement with that in the small clusters of just a few molecules in the original nuclei. "This means that the forces and factors that determine the process are constant throughout the growth of the crystal," says Neumann. "We have really observed an elementary event in the world of chemistry," says Neumann. "The findings are also leading us into new inquiries in this area, looking at the effects and significance of dense-phases on chemical reactivity." More information: Roy E. Schreiber et al. Real-time molecular scale observation of crystal formation, Nature Chemistry (2016). DOI: 10.1038/nchem.2675
Groult H.,CIBER ISCIII |
Ruiz-Cabello J.,CIBER ISCIII |
Ruiz-Cabello J.,Complutense University of Madrid |
Pellico J.,CIBER ISCIII |
And 8 more authors.
Bioconjugate Chemistry | Year: 2015
Multifunctional nanoparticles are usually produced by sequential synthesis, with long multistep protocols. Our study reports a generic modular strategy for the parallel one-step multifunctionalization of different hydrophobic nanoparticles. The method was designed and developed by taking advantage of the natural noncovalent interactions between the fatty acid binding sites of the bovine serum albumin (BSA) and the aliphatic surfactants on different inorganic nanomaterials. As a general example of the approach, three different nanoparticles-iron oxide, upconverting nanophosphors, and gold nanospheres-were nanoemulsified in water with BSA. To support specific applications, multifunctional capability was incorporated with a variety of previously modified BSA modules. These modules include different conjugated groups, such as chelating agents for 68Ga or 89Zr and ligand molecules for enhanced in vivo targeting. A large library of 13 multimodal contrast agents was developed with this convergent strategy. This platform allows a highly versatile and easy tailoring option for efficient incorporation of functional groups. Finally, as demonstration of this versatility, a bimodal (PET/MRI) probe including a maleimide-conjugated BSA was selectively synthesized with an RGD peptide for in vivo imaging detection of tumor angiogenesis. © 2014 American Chemical Society.
Valiente-Alandi I.,Spanish National Cardiovascular Research Center |
Valiente-Alandi I.,Cincinnati Childrens Hospital Medical Center |
Albo-Castellanos C.,Spanish National Cardiovascular Research Center |
Herrero D.,Spanish National Cardiovascular Research Center |
And 9 more authors.
Stem Cell Research and Therapy | Year: 2015
Introduction: The mammalian adult heart maintains a continuous, low cardiomyocyte turnover rate throughout life. Although many cardiac stem cell populations have been studied, the natural source for homeostatic repair has not yet been defined. The Polycomb protein BMI1 is the most representative marker of mouse adult stem cell systems. We have evaluated the relevance and role of cardiac Bmi1+ cells in cardiac physiological homeostasis. Methods: Bmi1CreER/+;Rosa26YFP/+ (Bmi1-YFP) mice were used for lineage tracing strategy. After tamoxifen (TM) induction, yellow fluorescent protein (YFP) is expressed under the control of Rosa26 regulatory sequences in Bmi1+ cells. These cells and their progeny were tracked by FACS, immunofluorescence and RT-qPCR techniques from 5 days to 1 year. Results: FACS analysis of non-cardiomyocyte compartment from TM-induced Bmi1-YFP mice showed a Bmi1 +-expressing cardiac progenitor cell (Bmi1-CPC: B-CPC) population, SCA-1 antigen-positive (95.9 ± 0.4 %) that expresses some stemness-associated genes. B-CPC were also able to differentiate in vitro to the three main cardiac lineages. Pulse-chase analysis showed that B-CPC remained quite stable for extended periods (up to 1 year), which suggests that this Bmi1+ population contains cardiac progenitors with substantial self-maintenance potential. Specific immunostaining of Bmi1-YFP hearts serial sections 5 days post-TM induction indicated broad distribution of B-CPC, which were detected in variably sized clusters, although no YFP+ cardiomyocytes (CM) were detected at this time. Between 2 to 12 months after TM induction, YFP+ CM were clearly identified (3 ± 0.6 % to 6.7 ± 1.3 %) by immunohistochemistry of serial sections and by flow cytometry of total freshly isolated CM. B-CPC also contributed to endothelial and smooth muscle (SM) lineages in vivo. Conclusions: High Bmi1 expression identifies a non-cardiomyocyte resident cardiac population (B-CPC) that contributes to the main lineages of the heart in vitro and in vivo. © 2015 Valiente-Alandi et al.
Skowronek F.,Laboratory of Molecular Biology of Reproduction |
Skowronek F.,Microscopy Unit |
Casanova G.,Microscopy Unit |
Alciaturi J.,Laboratory of Molecular Biology of Reproduction |
And 4 more authors.
Andrologia | Year: 2012
Sperm morphology has consistently been the best indicator of male fertility. Transmission electron microscopy currently provides the most information on the subcellular details of sperm structure. Recently, assessment of sperm DNA damage has been employed to assess fertility potential. The purpose of this work was to link sperm DNA damage, evaluated by an intercalated fluorescent dye, with the structural characteristics of sperm. Conventional semen analysis was performed on samples from men undergoing fertility evaluation. Thirty men were evaluated and assigned to three subgroups based on strict criteria for sperm morphology: normal morphology (>14% normal forms), intermediate morphology (5-14% normal forms), and poor morphology (<5% normal forms). By quantifying acridine orange-positive cells and ultrastructural sperm defects, we found that the poor morphology pattern group showed a positive association between sperm carrying damaged DNA and the percentage of sperm nucleus with vacuoles (P=0.01). No statistically significant correlations were established in other ultrastructural characteristics of sperm, including immature chromatin, lytic changes, or abnormal sperm tails. These results suggest that zones without chromatin in the sperm nucleus reflect underlying chromosomal or DNA defects in severe teratozoospermic men. This association should be considered in the evaluation of male fertility. © 2011 Blackwell Verlag GmbH.
Gamliel-Atinsky E.,University of Georgia |
Freeman S.,Israel Agricultural Research Organization |
Maymon M.,Israel Agricultural Research Organization |
Belausov E.,Microscopy Unit |
And 5 more authors.
Experimental and Applied Acarology | Year: 2010
A considerable number of plant feeding mites representing different families such as Acaridae, Siteroptidae, Tydeidae, and Tarsonemidae interact with plant pathogenic fungi. While species within the Eriophyoidea appear to be the most common phytophagous mites vectoring virus diseases, little is known of their role in fungal pathogen epidemiology. In the present article, we present two studies on eriophyoid-fungal relationships. The first focusing on the association between Aceria mangiferae and the fungal pathogen Fusarium mangiferae in mango is presented as a case study. The second, as the research is still in a preliminary phase, reports on quantitative and descriptive associations between the cereal rust mite Abacarus hystrix and rusts caused by Puccinia spp. Mango bud tissue colonized with F. mangiferae, and wheat and quackgrass leaves colonized with Puccinia spp., supported significantly higher populations of eriophyoid mites. Both mite species were observed bearing the spores of the respective pathogens on their body integument. Aceria mangiferae vectored the pathogen's spores into the bud, the sole port of entry for the fungal pathogen and the frequency and severity of fungal infection increased in the presence of A. mangiferae. While it appears that eriophyoids are playing a role in fungal epidemiology, clearly further research is needed to enhance our understanding of direct and indirect (plant mediated) interactions between plant pathogens and eriophyoid mites in different plant-pathogen systems. © 2009 Springer Science+Business Media B.V.
Sanchez S.,University of California at Irvine |
Sanchez S.,Microscopy Unit |
Bakas L.,National University of La Plata |
Gratton E.,University of California at Irvine |
Herlax V.,National University of La Plata
PLoS ONE | Year: 2011
α-Hemolysin (HlyA) from Escherichia coli is considered as the prototype of a family of toxins called RTX (repeat in toxin), a group of proteins that share genetic and structural features. HlyA is an important virulence factor in E. coli extraintestinal infections, such as meningitis, septicemia and urinary infections. High concentrations of the toxin cause the lysis of several cells such as erythrocytes, granulocytes, monocytes, endothelial and renal epithelial cells of different species. At low concentrations it induces the production of cytokines and apoptosis. Since many of the subcytolytic effects in other cells have been reported to be triggered by the increase of intracellular calcium, we followed the calcium concentration inside the erythrocytes while incubating with sublytic concentrations of HlyA. Calcium concentration was monitored using the calcium indicator Green 1, 2-photon excitation, and fluorescence lifetime imaging microscopy (FLIM). Data were analyzed using the phasor representation. In this report, we present evidence that, at sublytic concentrations, HlyA induces an increase of calcium concentration in rabbit erythrocytes in the first 10 s. Results are discussed in relation to the difficulties of measuring calcium concentrations in erythrocytes where hemoglobin is present, the contribution of the background and the heterogeneity of the response observed in individual cells. © 2011 Sanchez et al.
Ramella N.A.,CONICET |
Ramella N.A.,National University of La Plata |
Rimoldi O.J.,CONICET |
Rimoldi O.J.,National University of La Plata |
And 11 more authors.
PLoS ONE | Year: 2011
Amyloidoses constitute a group of diseases in which soluble proteins aggregate and deposit extracellularly in tissues. Nonhereditary apolipoprotein A-I (apoA-I) amyloid is characterized by deposits of nonvariant protein in atherosclerotic arteries. Despite being common, little is known about the pathogenesis and significance of apoA-I deposition. In this work we investigated by fluorescence and biochemical approaches the impact of a cellular microenvironment associated with chronic inflammation on the folding and pro-amyloidogenic processing of apoA-I. Results showed that mildly acidic pH promotes misfolding, aggregation, and increased binding of apoA-I to extracellular matrix elements, thus favoring protein deposition as amyloid like-complexes. In addition, activated neutrophils and oxidative/proteolytic cleavage of the protein give rise to pro amyloidogenic products. We conclude that, even though apoA-I is not inherently amyloidogenic, it may produce non hereditary amyloidosis as a consequence of the pro-inflammatory microenvironment associated to atherogenesis. © 2011 Ramella et al.
Garcia-Beccaria M.,Telomeres and Telomerase Group |
Martinez P.,Telomeres and Telomerase Group |
Mendez-Pertuz M.,Telomeres and Telomerase Group |
Martinez S.,Spanish National Cancer Research Center |
And 9 more authors.
EMBO Molecular Medicine | Year: 2015
Telomeres are considered anti-cancer targets, as telomere maintenance above a minimum length is necessary for cancer growth. Telomerase abrogation in cancer-prone mouse models, however, only decreased tumor growth after several mouse generations when telomeres reach a critically short length, and this effect was lost upon p53 mutation. Here, we address whether induction of telomere uncapping by inhibition of the TRF1 shelterin protein can effectively block cancer growth independently of telomere length. We show that genetic Trf1 ablation impairs the growth of p53-null K-RasG12V-induced lung carcinomas and increases mouse survival independently of telomere length. This is accompanied by induction of telomeric DNA damage, apoptosis, decreased proliferation, and G2 arrest. Long-term whole-body Trf1 deletion in adult mice did not impact on mouse survival and viability, although some mice showed a moderately decreased cellularity in bone marrow and blood. Importantly, inhibition of TRF1 binding to telomeres by small molecules blocks the growth of already established lung carcinomas without affecting mouse survival or tissue function. Thus, induction of acute telomere uncapping emerges as a potential new therapeutic target for lung cancer. © 2015 The Authors. Published under the terms of the CC BY 4.0 license.
PubMed | Howard Hughes Medical Institute, Microscopy Unit, Spanish National Cardiovascular Research Center and CIEMAT
Type: | Journal: Stem cell research & therapy | Year: 2015
The mammalian adult heart maintains a continuous, low cardiomyocyte turnover rate throughout life. Although many cardiac stem cell populations have been studied, the natural source for homeostatic repair has not yet been defined. The Polycomb protein BMI1 is the most representative marker of mouse adult stem cell systems. We have evaluated the relevance and role of cardiac Bmi1 (+) cells in cardiac physiological homeostasis.Bmi1 (CreER/+);Rosa26 (YFP/+) (Bmi1-YFP) mice were used for lineage tracing strategy. After tamoxifen (TM) induction, yellow fluorescent protein (YFP) is expressed under the control of Rosa26 regulatory sequences in Bmi1 (+) cells. These cells and their progeny were tracked by FACS, immunofluorescence and RT-qPCR techniques from 5 days to 1 year.FACS analysis of non-cardiomyocyte compartment from TM-induced Bmi1-YFP mice showed a Bmi1 (+)-expressing cardiac progenitor cell (Bmi1-CPC: B-CPC) population, SCA-1 antigen-positive (95.90.4 %) that expresses some stemness-associated genes. B-CPC were also able to differentiate in vitro to the three main cardiac lineages. Pulse-chase analysis showed that B-CPC remained quite stable for extended periods (up to 1 year), which suggests that this Bmi1 (+) population contains cardiac progenitors with substantial self-maintenance potential. Specific immunostaining of Bmi1-YFP hearts serial sections 5 days post-TM induction indicated broad distribution of B-CPC, which were detected in variably sized clusters, although no YFP(+) cardiomyocytes (CM) were detected at this time. Between 2 to 12 months after TM induction, YFP(+) CM were clearly identified (30.6 % to 6.71.3 %) by immunohistochemistry of serial sections and by flow cytometry of total freshly isolated CM. B-CPC also contributed to endothelial and smooth muscle (SM) lineages in vivo.High Bmi1 expression identifies a non-cardiomyocyte resident cardiac population (B-CPC) that contributes to the main lineages of the heart in vitro and in vivo.
News Article | March 6, 2016
New research has proposed a design for a submerged marine turbine that could harness ocean currents as a potential renewable energy resource. Researchers from the Quantum Wave Microscopy Unit at Okinawa Institute of Science and Technology Graduate University (OIST) have published their proposition in the journal Renewable Energy. The researchers specifically proposed a submerged marine turbine that could harness the energy of the Kuroshio Current, a north-flowing ocean current on the west side of the North Pacific Ocean, up against Japan’s own east coast. The Kuroshio Current is similar to the more well-known Gulf Stream current that runs around the top side of the Atlantic Ocean, and could provide consistent electricity much like fossil fuels have done. The newly proposed design could see a submerged marine turbine operate in the middle layer of the Kuroshio Current, 100 metres below the surface, where the waters of the current flow steadily and relatively calmly, even during the violent storms and typhoons that make their home in the region. The design itself is more a hybrid of a kite and a wind turbine, and comprises a float, a counterweight, a nacelle to house the electricity generating components, and three blades. The turbine would be anchored to the seabed, while its position in the current would turn the blades, generating near-constant electricity. As the researchers note, though ocean currents are relatively slow — averaging only 1-1.5 m/s — water is over 800 times more dense than air, meaning that even slow ocean currents are comparable to strong winds — and with the added benefit of being constant in both direction and speed. Get CleanTechnica’s 1st (completely free) electric car report → “Electric Cars: What Early Adopters & First Followers Want.” Come attend CleanTechnica’s 1st “Cleantech Revolution Tour” event → in Berlin, Germany, April 9–10. Keep up to date with all the hottest cleantech news by subscribing to our (free) cleantech newsletter, or keep an eye on sector-specific news by getting our (also free) solar energy newsletter, electric vehicle newsletter, or wind energy newsletter.