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991.
992.
Mathieu Boissan Sandrine Dabernat Evelyne Peuchant Uwe Schlattner Ioan Lascu Marie-Lise Lacombe 《Molecular and cellular biochemistry》2009,329(1-2):51-62
Nucleoside diphosphate kinases (NDPK) are encoded by the NME genes, also called NM23. They catalyze the transfer of γ-phosphate from nucleoside triphosphates to nucleoside diphosphates by a ping-pong mechanism involving the formation of a high energy phospho-histidine intermediate [1, 2]. Besides their known functions in the control of intracellular nucleotide homeostasis, they are involved in multiple physiological and pathological cellular processes such as differentiation, development, metastastic dissemination or cilia functions. Over the past 15 years, ten human genes have been discovered encoding partial, full length, and/or tandemly repeated Nm23/NDPK domains, with or without N-or C-terminal extensions and/or additional domains. These genes encode proteins exhibiting different functions at various tissular and subcellular localizations. Most of these genes appear late in evolution with the emergence of the vertebrate lineage. This review summarizes the present knowledge on these multitalented proteins. 相似文献
993.
Aliaksandr A. Halavatyi Petr V. Nazarov Sandrine Medves Marleen van Troys Christophe Ampe Mikalai Yatskou Evelyne Friederich 《Biophysical chemistry》2009,140(1-3):24-34
We report on an advanced universal Monte Carlo simulation model of actin polymerization processes offering a broad application panel. The model integrates major actin-related reactions, such as assembly of actin nuclei, association/dissociation of monomers to filament ends, ATP-hydrolysis via ADP-Pi formation and ADP-ATP exchange, filament branching, fragmentation and annealing or the effects of regulatory proteins. Importantly, these reactions are linked to information on the nucleotide state of actin subunits in filaments (ATP hydrolysis) and the distribution of actin filament lengths. The developed stochastic simulation modelling schemes were validated on: i) synthetic theoretical data generated by a deterministic model and ii) sets of our and published experimental data obtained from fluorescence pyrene-actin experiments. Build on an open-architecture principle, the designed model can be extended for predictive evaluation of the activities of other actin-interacting proteins and can be applied for the analysis of experimental pyrene actin-based or fluorescence microscopy data. We provide a user-friendly, free software package ActinSimChem that integrates the implemented simulation algorithms and that is made available to the scientific community for modelling in silico any specific actin-polymerization system. 相似文献
994.
995.
Sandrine Pavoine Jeanne Vallet Anne‐Béatrice Dufour Sophie Gachet Hervé Daniel 《Oikos》2009,118(3):391-402
Functional diversity is at the heart of current research in the field of conservation biology. Most of the indices that measure diversity depend on variables that have various statistical types (e.g. circular, fuzzy, ordinal) and that go through a matrix of distances among species. We show how to compute such distances from a generalization of Gower's distance, which is dedicated to the treatment of mixed data. We prove Gower's distance can be extended to include new types of data. The impact of this generalization is illustrated on a real data set containing 80 plant species and 13 various traits. Gower's distance allows an efficient treatment of missing data and the inclusion of variable weights. An evaluation of the real contribution of each variable to the mixed distance is proposed. We conclude that such a generalized index will be crucial for analyzing functional diversity at small and large scales. 相似文献
996.
997.
The spatial pattern of life strategies gives us clues about what factors are important for structuring the vegetation and
at which scale they work. In this study, we look at the spatial distribution of the CSR-strategies of Grime on a meso-scale
(larger than 50 m × 50 m) in a temperate forest. To detect the spatial pattern of the different life forms, 79 plant species
were surveyed according to a grid with 2431 cells of 50 m × 50 m. For each cell C, S and R-values were calculated and their spatial distribution was studied. The spatial patterns were then explained by available
environmental factors. The different plant strategies clearly showed an aggregated pattern on a scale larger than 50 m × 50 m.
This non-random and unequal distribution of the different life strategies could be explained by the factors that are under
the control of the forest management, namely “distance to road” and “dominant (planted) tree species”. Patches with high C-values (C-biotopes) where found under pine, S-biotopes where found under mixed oak-beech and pure beech stands of 100 to 150 years old. R-biotopes were bound to the roads. 相似文献
998.
Martínez-Barbosa ME Cammas-Marion S Bouteiller L Vauthier C Ponchel G 《Bioconjugate chemistry》2009,20(8):1490-1496
In the present work, the possibility to obtain PEGylated nanoparticles from two PBLG derivatives, PEG-b-poly(γ-benzyl L-glutamate), PBLG-PEG-60, and poly(γ-benzyl L-glutamate), PBLG-Bnz-50, by nanoprecipitation has been investigated. Particles were prepared not only from one polymer (PBLG-PEG-60 or PBLG-Bnz-50), but also from mixtures of two PBLG derivatives, PBLG-PEG-60 and PBLG-Bnz-50, in different ratios (90/10, 77/23, and 40/60 wt %). Because of the presence of PEG chains, hydrophilic particles were obtained, which was confirmed by ζ potential measurements (ζ from -13 mV and -21 mV) and by isothermal titration microcalorimetry (ITC). This last technique has shown no heat exchange when BSA was added to PEGylated nanoparticles. Further, complement activation has been evaluated by crossed immuno-electrophoresis demonstrating that the introduction of 77 wt % of PEGylated PBLG chains in the particles was enough to ensure a low complement activation activity. This effect was strongly correlated to the ζ potential of the particles, which decreased with an increase of PEG chains content. Interestingly, such properties are of interest for the preparation of degradable stealth nanocarriers. Moreover, it is suggested that the introduction of a reasonable amount (up to 20 wt %) of a second copolymer in the particle composition can be possible without modifying their stealth character. Moreover, the presence of this second copolymer would help to introduce a second functionality to the particles. 相似文献
999.
Sebastien Elis Elisabeth Blesbois Isabelle Couty Sandrine Balzergue Marie‐Laure Martin‐Magniette Florence Batellier Marina S. Govoroun 《Molecular reproduction and development》2009,76(11):1043-1055
Despite the regular decrease in fertility observed in hens, especially in “meat” lines, little is known about genes affecting fertility. We used the Affymetrix microarray to search for oocyte genes whose expression would vary in relation to fertility rate in both “laying” and “meat” line hens. We focused on oocyte genes because several of them have been found to be involved in fertility in other species. Based on microarray analysis, 54 and 84 genes were differentially expressed between germinal disc regions (GDR) of F1 maturation stage oocytes from hens exhibiting either high (100%) or low (from 22% to 80%) fertility rate from laying and meat lines respectively. Most of these differentially expressed genes were distributed between “laying” and “meat” lines indicating that mechanisms involved in the decrease in fertility rates in these two cases were independent. Real time RT‐PCR performed on the same samples which were used for microarray confirmed in several cases differences in gene expression levels detected by microarray. Moreover the correlations between gene expression levels and fertility rates were evaluated for the 10 most interesting genes at different stages of follicular maturation and early embryo development on individual GDR samples from hens exhibiting different fertility rates. In total, we identified five genes whose expression levels correlated with fertility rate in accordance with findings of microarray analysis and real time RT‐PCR: VWC2, CR407412, TAPA, FGL2, and TRAP6. The biological significance of these genes sheds light on potential mechanisms influencing fertility and could provide candidates for fertility markers in the hen. Mol. Reprod. Dev. 76: 1043–1055, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
1000.
Lisa Miranda Anna Platek Marie-Agnès Gueuning Yurda Ozkan Louis Hue Mark H. Rider Sandrine Horman 《Biochemical and biophysical research communications》2010,396(3):656-219
AMP-activated protein kinase (AMPK), a known regulator of cellular and systemic energy balance, is now recognized to control cell division, cell polarity and cell migration, all of which depend on the actin cytoskeleton. Here we report the effects of A769662, a pharmacological activator of AMPK, on cytoskeletal organization and signalling in epithelial Madin-Darby canine kidney (MDCK) cells. We show that AMPK activation induced shortening or radiation of stress fibers, uncoupling from paxillin and predominance of cortical F-actin. In parallel, Rho-kinase downstream targets, namely myosin regulatory light chain and cofilin, were phosphorylated. These effects resembled the morphological changes in MDCK cells exposed to hyperosmotic shock, which led to Ca2+-dependent AMPK activation via calmodulin-dependent protein kinase kinase-β(CaMKKβ), a known upstream kinase of AMPK. Indeed, hypertonicity-induced AMPK activation was markedly reduced by the STO-609 CaMKKβ inhibitor, as was the increase in MLC and cofilin phosphorylation. We suggest that AMPK links osmotic stress to the reorganization of the actin cytoskeleton. 相似文献