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151.
Fabrice Lefevre Cyrille Jarrin Aurelien Ginolhac Daniel Auriol Renaud Nalin 《Biocatalysis and Biotransformation》2007,25(2):242-250
The current existing enzymes have been identified from cultivable micro-organisms, most frequently from bacteria. These bacterial biocatalytic capabilities have been widely used for biotransformations, resulting in the development of profitable industrial bioprocesses in the fields of feed and food processing, textiles, agro-chemistry, cosmetics, pharmaceuticals and fine chemistry. However, the originality of this bioresource is progressively drying up, while requests from industry for novel biocatalytic activities are increasing in the face of economic and environmental pressure. Metagenomics, through access to the huge reservoir of uncultivated bacteria which represents the majority of the present biodiversity, opens the door to new industrial sources of enzymes. Surmounting hurdles encountered with this technology (e.g. DNA extraction to obtain high quality DNA libraries with proper statistical representativity, setting up of relevant high throughput screenings assays, combining functional and genome-based identifications), gives unique opportunities to access novel biocatalysts that better fit with the required industrial specifications, thus providing new biocatalysis tool boxes. 相似文献
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153.
Understanding the imprint of environmental filtering on community assembly along environmental gradients is a key objective of trait‐gradient analyses. Depending on local constraints, this filtering generally entails that species departing from an optimum trait value have lower abundances in the community. The community‐weighted mean (CWM) and variance (CWV) of trait values are then expected to depict the optimum and intensity of filtering, respectively. However, the trait distribution within the regional species pool and its limits can also affect local CWM and CWV values apart from the effect of environmental filtering. The regional trait range limits are more likely to be reached in communities at the extremes of environmental gradients. Analogous to the mid‐domain effect in biogeography, decreasing CWV values in extreme environments can then represent the influence of regional trait range limits rather than stronger filtering in the local environment. We name this effect the ‘trait‐gradient boundary effect’ (TGBE). First, we use a community assembly framework to build simulated communities along a gradient from a species pool and environmental filtering with either constant or varying intensity while accounting for immigration processes. We demonstrate the significant influence of TGBE, in parallel to environmental filtering, on CWM and CWV at the extremes of the environmental gradient. We provide a statistical tool based on Approximate Bayesian Computation to decipher the respective influence of local environmental filtering and regional trait range limits. Second, as a case study, we reanalyze the functional composition of alpine plant communities distributed along a gradient of snow cover duration. We show that leaf trait convergence found in communities at the extremes of the gradient reflect an influence of trait range limits rather than stronger environmental filtering. These findings challenge correlative trait–environment relationships and call for more explicitly identifying the mechanisms responsible of trait convergence/divergence along environmental gradients. 相似文献
154.
Nicolas Delpierre Sgolne Lireux Florian Hartig Jesus Julio Camarero Alissar Cheaib Katarina ufar Henri Cuny Annie Deslauriers Patrick Fonti Joica Gri
ar Jian‐Guo Huang Cornelia Krause Guohua Liu Martin de Luis Harri Mkinen Edurne Martinez del Castillo Hubert Morin Pekka Njd Walter Oberhuber Peter Prislan Sergio Rossi Seyedeh Masoumeh Saderi Vaclav Treml Hanus Vavrick Cyrille B. K. Rathgeber 《Global Change Biology》2019,25(3):1089-1105
The phenology of wood formation is a critical process to consider for predicting how trees from the temperate and boreal zones may react to climate change. Compared to leaf phenology, however, the determinism of wood phenology is still poorly known. Here, we compared for the first time three alternative ecophysiological model classes (threshold models, heat‐sum models and chilling‐influenced heat‐sum models) and an empirical model in their ability to predict the starting date of xylem cell enlargement in spring, for four major Northern Hemisphere conifers (Larix decidua, Pinus sylvestris, Picea abies and Picea mariana). We fitted models with Bayesian inference to wood phenological data collected for 220 site‐years over Europe and Canada. The chilling‐influenced heat‐sum model received most support for all the four studied species, predicting validation data with a 7.7‐day error, which is within one day of the observed data resolution. We conclude that both chilling and forcing temperatures determine the onset of wood formation in Northern Hemisphere conifers. Importantly, the chilling‐influenced heat‐sum model showed virtually no spatial bias whichever the species, despite the large environmental gradients considered. This suggests that the spring onset of wood formation is far less affected by local adaptation than by environmentally driven plasticity. In a context of climate change, we therefore expect rising winter–spring temperature to exert ambivalent effects on the spring onset of wood formation, tending to hasten it through the accumulation of forcing temperature, but imposing a higher forcing temperature requirement through the lower accumulation of chilling. 相似文献
155.
Matthew McLean Arnaud Auber Nicholas A. J. Graham Peter Houk Sbastien Villger Cyrille Violle Wilfried Thuiller Shaun K. Wilson David Mouillot 《Global Change Biology》2019,25(10):3424-3437
Trait diversity is believed to influence ecosystem dynamics through links between organismal traits and ecosystem processes. Theory predicts that key traits and high trait redundancy—large species richness and abundance supporting the same traits—can buffer communities against environmental disturbances. While experiments and data from simple ecological systems lend support, large‐scale evidence from diverse, natural systems under major disturbance is lacking. Here, using long‐term data from both temperate (English Channel) and tropical (Seychelles Islands) fishes, we show that sensitivity to disturbance depends on communities’ initial trait structure and initial trait redundancy. In both ecosystems, we found that increasing dominance by climatically vulnerable traits (e.g., small, fast‐growing pelagics/corallivores) rendered fish communities more sensitive to environmental change, while communities with higher trait redundancy were more resistant. To our knowledge, this is the first study demonstrating the influence of trait structure and redundancy on community sensitivity over large temporal and spatial scales in natural systems. Our results exemplify a consistent link between biological structure and community sensitivity that may be transferable across ecosystems and taxa and could help anticipate future disturbance impacts on biodiversity and ecosystem functioning. 相似文献
156.
Exploring sub‐individual variability: role of ontogeny,abiotic environment and seed‐dispersing birds
M. Sobral J. Guitin P. Guitin C. Violle A. R. Larrinaga 《Plant biology (Stuttgart, Germany)》2019,21(4):688-694
- Within‐individual trait variation – otherwise known as sub‐individual variation – is an important component of phenotypic variation, with both a genetic and epigenetic basis. We explore its adaptive value and the effects of ontogeny and the environment on sub‐individual variability.
- We conducted a field study to analyse the effects of tree age, soil pH, soil water content and soil nutrients on sub‐individual variability in fruit size of hawthorn (Crataegus monogyna) in three sites in northwest Spain. Additionally, we examined how bird‐mediated selection influences average and sub‐individual variation in fruit size.
- Results show that average and sub‐individual variations in fruit size were related to fitness affecting seed dispersal. Older trees produced larger fruits, but tree age did not affect sub‐individual variation in fruit size. Abiotic environmental factors differently affected sub‐individual variation and average fruit size. Seed‐dispersing birds exerted correlated selection on average and variation in fruit size, favouring trees with larger and less variable fruit size at one site.
- Our work suggests that the fruit size variation within individual trees, the sub‐individual variation, is modified by abiotic environmental factors and, additionally, is an adaptive trait that responds to natural selection.
157.
Hagen Hofmann Frank Hillger Cyrille Delley Armin Hoffmann Shawn?H. Pfeil Daniel Nettels Everett?A. Lipman Benjamin Schuler 《Biophysical journal》2014,107(12):2891-2902
The bacterial chaperonin GroEL/GroES assists folding of a broad spectrum of denatured and misfolded proteins. Here, we explore the limits of this remarkable promiscuity by mapping two denatured proteins with very different conformational properties, rhodanese and cyclophilin A, during binding and encapsulation by GroEL/GroES with single-molecule spectroscopy, microfluidic mixing, and ensemble kinetics. We find that both proteins bind to GroEL with high affinity in a reaction involving substantial conformational adaptation. However, whereas the compact denatured state of rhodanese is encapsulated efficiently upon addition of GroES and ATP, the more expanded and unstructured denatured cyclophilin A is not encapsulated but is expelled into solution. The origin of this surprising disparity is the weaker interactions of cyclophilin A with a transiently formed GroEL-GroES complex, which may serve as a crucial checkpoint for substrate discrimination. 相似文献
158.
159.
Manishkumar Patel Alexa Gleason Stacey O'Malley Brett Connolly Donna Suresch John Virostko Neil Phillips Shu-An Lin Tsing-Bau Chen Michael Klimas Richard J. Hargreaves Cyrille Sur David L. Williams Jr Alvin C. Powers Bohumil Bednar 《PloS one》2014,9(9)
Background
Type 2 diabetes results from failure of the β-cells to compensate for increased insulin demand due to abnormal levels of metabolic factors. The ob/ob(lep-/-) mouse has been extensively studied as an animal model of type 2 diabetes. Previous studies have shown a correlation between β-cell function and bioluminescent imaging in lean genetically engineered mice. The ability to noninvasively monitor β-cell function in ob/ob mice could provide new information on β-cell regulation in type 2 diabetes.Methods
To create the B6 Albino ob/ob MIP-luc mice (ob/ob-luc), the ob/ob mouse was crossed with the CD1 MIP-luc mouse. All mice were backcrossed over multiple generations to ensure the genetic background of the transgenic mice was over 96% similar to the background of the original ob/ob mouse. Animal weight, blood glucose levels, insulin in plasma, and in vivo bioluminescence (BLI) were monitored weekly or biweekly for up to 70 weeks of age. BL imaging was performed using IVIS Spectrum (Perkin Elmer) and calculated by integrating the bioluminescence signal between 5 and 10 min after i.v. injection of D-luciferin. Insulin immunohistochemistry determined islet beta cell count and insulin secretion assay determined islet insulin function.Results
There were significant increases in BLI and insulin levels as the ob/ob-luc mice aged while glucose levels gradually decreased. Ob/ob-luc were sacrificed at different time points to determine ex vivo BLI, islet function and total β-cell numbers using a cell counting training algorithm developed for the Vectra image analysis system (Perkin Elmer). The number of β-cells increased as the mice aged and all three ex vivo measurements correlated with BLI.Conclusions
The ob/ob-luc mice can serve as a model of metabolic stress, similar to human type 2 diabetes using BLI as a surrogate marker for β-cell function. 相似文献160.
Cyrille P. Launay Laure de Decker Anastasiia Kabeshova Cédric Annweiler Olivier Beauchet 《PloS one》2014,9(10)