1H high resolution magic-angle coil spinning (HR-MACS) μNMR metabolic profiling of whole Saccharomyces cervisiae cells: a demonstrative study

International audienceThe low sensitivity and thus need for large sample volume is one of the major drawbacks of Nuclear Magnetic Resonance (NMR) spectroscopy. This is especially problematic for performing rich metabolic profiling of scarce samples such as whole cells or living organisms. This study evaluates a 1H HR-MAS approach for metabolic profiling of small volumes (250 nl) of whole cells. We have applied an emerging micro-NMR technology, high-resolution magic-angle coil spinning (HR-MACS), to study whole Saccharomyces cervisiae cells. We find that high-resolution high-sensitivity spectra can be obtained with only 19 million cells and, as a demonstration of the metabolic profiling potential, we perform two independent metabolomics studies identifying the significant metabolites associated with osmotic stress and agin

Atrazine contamination at the watershed scale and environmental factors affecting sampling rates of the polar organic chemical integrative sampler (POCIS)

AbstractPolar organic chemical integrative samplers (POCIS) were used to estimate atrazine contamination at 24 stream/river sites located across a watershed with land use ranging from 6.7 to 97.4% annual crops and surface water nitrate concentrations ranging from 3 to 5404 μg/L. A gradient of atrazine contamination spanning two orders of magnitude was observed over two POCIS deployments of 28 d and was positively correlated with measures of agricultural intensity. The metabolite desisopropyl atrazine was used as a performance reference compound in field calibration studies. Sampling rates were similar between field sites but differed seasonally. Temperature had a significant effect on sampling rates while other environmental variables, including water velocity, appeared to have no effect on sampling rates. A performance reference compound approach showed potential in evaluating spatial and temporal differences in field sampling rates and as a tool for further understanding processes governing uptake of polar compounds by POCIS

Dynamique atypique de structures réticulées

La dynamique de poutres et de milieux réticulés composés de cellules périodiques non contreventées est étudiée avec la méthode d'homogénéisation des milieux périodiques discrets. Par rapport à des milieux massifs, ce type de microstructure peut présenter un fort contraste entre déformabilités de compression et de cisaillement, ce qui génère une cinématique locale plus riche (rotation globale, déformation ou résonance interne) selon la structure et la gamme de fréquence. Ces fonctionnements atypiques sont décrits théoriquement et illustrés sur des exemples numériques et des structures réelles

Open Journal of Ecology Bush, bugs, and birds; interdependency in a farming landscape

ABSTRACT Changes in farming practices over the second half of the twentieth century greatly reduced the extent of natural areas remaining within agricultural landscapes. Field margins and hedgerows have recently been recognized as important habitat in maintaining wildlife diversity and proper ecosystem functioning. Ecotones, defined as the transitionary area of vegetation between woody plant species and the arable crop, are an especially important landscape element for birds and arthropods. In this manuscript, we aimed to evaluate which hedgerow attribute was best at predicting avian densities in a conventional and organic farming landscape. Furthermore, we wished to investigate if these same hedgerow attributes could explain arthropod family density, richness and diversity, and how these were correlated to avian densities. An information theory-based multimodel inference method was used to identify which factors influenced variability in avian densities. Although not always significant, avian densities increased with arthropod richness at our study sites. Ecotone width is the best predictor of avian densities and arthropod richness while percent gap is the most important factor if a manager wishes to increase avian diversity (H') in hedgerow habitats. Increasing ecotone width benefits both avian densities and arthropod richness that in turn further increases bird numbers in our farming landscape

Rim-functionalized cryptophane-111 derivatives via heterocapping, and their xenon complexes

International audienceCapping of cyclotriphenolene (3a) by the more available cyclotriguaiacylene (3c) or trisbromocyclotriphenolene (3b) gives the first rim-functionalized cryptophane-111 derivatives. Crystal structures of the xenon complexes reveal high cavity packing coefficients and unprecedentedly short Xe...C contacts

Spin-Exchange optical pumping in a van

International audienceThe advent of spin-hyperpolarization techniques designed to overcome the sensitivity issue of nuclear magnetic resonance owing to polarization transfer from more ordered systems has recently raised great enthusiasm. However, the out-of-equilibrium character of the polarization requires a close proximity between the area of production and the site of use. We present here a mobile spin-exchange optical pumping setup that enables production of laser-polarized noble gases in a standalone mode, in close proximity to hospitals or research laboratories. Only compressed air and mains power need to be supplied by the host laborator

Genetic variance in fitness indicates rapid contemporary adaptive evolution in wild animals

Funding: Hoge Veluwe great tits: the NIOO-KNAW, ERC, and numerous funding agencies; Wytham great tits: Biotechnology and Biological Sciences Research Council, ERC, and the UK Natural Environment Research Council (NERC).The rate of adaptive evolution, the contribution of selection to genetic changes that increase mean fitness, is determined by the additive genetic variance in individual relative fitness. To date, there are few robust estimates of this parameter for natural populations, and it is therefore unclear whether adaptive evolution can play a meaningful role in short-term population dynamics. We developed and applied quantitative genetic methods to long-term datasets from 19 wild bird and mammal populations and found that, while estimates vary between populations, additive genetic variance in relative fitness is often substantial and, on average, twice that of previous estimates. We show that these rates of contemporary adaptive evolution can affect population dynamics and hence that natural selection has the potential to partly mitigate effects of current environmental change.PostprintPeer reviewe

Archiving primary data: solutions for long-term studies

The recent trend for journals to require open access to primary data included in publications has been embraced by many biologists, but has caused apprehension amongst researchers engaged in long-term ecological and evolutionary studies. A worldwide survey of 73 principal investigators (Pls) with long-term studies revealed positive attitudes towards sharing data with the agreement or involvement of the PI, and 93% of PIs have historically shared data. Only 8% were in favor of uncontrolled, open access to primary data while 63% expressed serious concern. We present here their viewpoint on an issue that can have non-trivial scientific consequences. We discuss potential costs of public data archiving and provide possible solutions to meet the needs of journals and researchers

Predicting bee community responses to land-use changes: Effects of geographic and taxonomic biases

Land-use change and intensification threaten bee populations worldwide, imperilling pollination services. Global models are needed to better characterise, project, and mitigate bees' responses to these human impacts. The available data are, however, geographically and taxonomically unrepresentative; most data are from North America and Western Europe, overrepresenting bumblebees and raising concerns that model results may not be generalizable to other regions and taxa. To assess whether the geographic and taxonomic biases of data could undermine effectiveness of models for conservation policy, we have collated from the published literature a global dataset of bee diversity at sites facing land-use change and intensification, and assess whether bee responses to these pressures vary across 11 regions (Western, Northern, Eastern and Southern Europe; North, Central and South America; Australia and New Zealand; South East Asia; Middle and Southern Africa) and between bumblebees and other bees. Our analyses highlight strong regionally-based responses of total abundance, species richness and Simpson's diversity to land use, caused by variation in the sensitivity of species and potentially in the nature of threats. These results suggest that global extrapolation of models based on geographically and taxonomically restricted data may underestimate the true uncertainty, increasing the risk of ecological surprises