Through the taste buds of a large herbivore: foodscape modeling contributes to an understanding of forage selection processes

How large herbivores track resource quantity and quality through time has formed the core of an abundance of literature on migratory populations in recent decades. Yet, relating foraging processes and habitat selection patterns in resident populations, where spatial heterogeneity of food resources is fine-grained and/or where the portion of edible plants (i.e. the foodscape) is low, is challenging. We addressed this issue in a mountain population of chamois Rupicapra rupicapra, an intermediate feeder, whose individuals do not migrate. We relied on a rare combination of data on habitat use of 50 GPS-collared females and data on the quantity (biomass) and quality (phenology) of edible resources in their landscape, derived from field sampling of vegetation, remote sensing and diet (DNA barcoding). The foodscape of the chamois was composed of a low proportion of the available biomass (<18%), including relatively high-quality plants, with low spatial covariation between plant phenology and biomass. Chamois avoided areas with a low edible biomass (where the intake rate may be too low) and focused on areas with plants at approximately the flowering stage, whatever the average plant phenological stage available. Due to this constant preference for flowering plants, home range selection ratios therefore shifted during the summer from a selection of more advanced plants in June to their avoidance in August. When the phenology scores of all plants available, rather than edible plants only, were considered, areas with relatively more advanced plants were selected all summer long. This exemplifies that, when traits from edible plants are different from those of all plants available, it is crucial to consider the actual foodscape to decipher forage and habitat selection processes. By integrating species-specific dimensions of resources in habitat selection studies, we believe understanding of the foraging processes will be improved.     

Carbon economy in walnut seedlings during the acquisition of autotrophy studied by long-term labelling with 13CO2

A closed growth chamber was designed to study the acquisition of autotrophy by seedlings of walnut ( Juglans regia L. cv. Lara) in controlled conditions (22°C, 12-h photoperiod) during the first two months of growth. The chamber consisted of two airtight compartments, in which continuous gas exchange was measured on the aerial and subterranean parts of several batches of tree seedlings. Long-term labelling with ¹³CO₂ was used in the chamber to study the import, distribution, and respiratory losses of photoassimilates (autotrophic carbon) in relation to the partitioning and use of reserves of the maternal seed (heterotrophic carbon). The carbon economy of walnut seedlings was estimated by measurements of gas exchange, carbon content, and ¹³C/¹²C isotopic ratio in dry matter and respiratory CO₂. The seedlings were entirely heterotrophic for energy and structural growth during the first 21 days after sowing. From day 22, photosynthesis appeared. At day 29, autotrophic carbon accounted for 25% and 30% of respiration in the root and shoot respectively; these proportions increased to 45% and 65% at day 54. The autotrophic carbon was incorporated into the dry matter of the shoot from day 32 but only after day 40 into the dry matter of the taproot. From day 32, the total contribution of heterotrophic carbon decreased regularly, and until day 43, it was essentially used for root growth. Thereafter, the contribution of heterotrophic carbon was negligible, and at day 54 the walnut seedlings were entirely autotrophic.     

Spatial distribution and habitat selection in coexisting species of mountain ungulates

One of the main objectives of community ecology is to understand the conditions allowing species to coexist, which requires identifying how co‐occurring species use and share space and resources. Species of the same trophic level, such as large herbivores, are of fundamental interest in that context because competition for resources is likely. Segregation in space or on some axes of the ecological niche are processes allowing coexistence, yet, both are seldom studied jointly. Based on annual spring censuses collected for 11 yr, we analysed the degree of overlap in spatial distribution among chamois Rupicapra rupicapra and mouflon Ovis gmelini musimon, 2 species of similar size that coexist on the same alpine pastures. We further investigated whether they differed in terms of habitat selection processes, and identified which environmental factors led to species being aggregated or segregated. The areas of intensive use for 2 species were more spatially aggregated than expected by chance. Habitat selection was studied using multivariate methods based on the niche concept, considering the presence of 1 species as an environmental variable for the other. Despite a large overlap in niches (88%), segregation was significant as chamois preferred meadows dominated by Sesleria and Carex sempervirens while mouflon selected meadows dominated by Carex ferruginea and avoided being close to areas affected by human activities. Importantly, habitat selection within each species was not affected by the presence of the other species. Coexistence between these 2 species and spatial overlap may be permitted because resource partitioning occurs at a fine temporal and/or spatial scale. We underscore that joint approaches of spatial and ecological processes are necessary to disclose the type of interaction (neutral, facilitation or competition) at play within a community.     

Evaluation of the effectiveness of commercially available contact plates for monitoring microbial environments

Aim:  The aim of this study was to measure the efficiency of contact plates to recover microbial contaminants from stainless steel surface.
Materials and Methods:  Three commercially available contact plates were used to recover two biological indicators from stainless steel sheets. The method used was standardised and validated to provide robust results. Parameters such as wetness, fertility and loss of water were also investigated for possible correlation with recovery efficiency.
Results:  The percentage of recovery from the contact plates was low and differences in recovery efficiency between brands depended upon the test organism. The poor recovery was probably due to the inability of the dried micro-organism to transfer to the plate, rather than the inability of the plate to grow the micro-organism. Wetness might help in improving recovery.
Conclusions:  The use of a validated protocol allowed robust investigations into the recovery efficiency of contact plates.
Significance and Impact of the Study:  The poor and variable recovery rates are of concern as they cast doubt on the comparability and reliability of environmental monitoring results where different commercial contact plates have been used.     

Energy dispersive analysis of X-rays study of the distribution of chlorhexidine diacetate and cetylpyridinium chloride on the Pseudomonas aeruginosa bacteriophage F116

Using an energy dispersive analyser of X-rays fitted to a scanning electron microscope, chlorhexidine was shown not to bind onto F116 bacteriophage, unlike cetylpyridinium chloride, which possibly penetrated the phage. This could explain the difference in viricidal activity between the two compounds.     

Evaluation of alcohol wipes used during aseptic manufacturing

Aim: During aseptic manufacturing and specifically during the transfer of items into an isolator, disinfection of surfaces is essential for reducing the risk of final product contamination. Surface disinfection can be carried out by a variety of methods, however the most accepted current practice is a combination of spraying with 70% alcohol and wiping. The aim of this study was to evaluate the effectiveness of two wipe systems by determining their ability to remove, kill and transfer bacterial contaminants from standardized surfaces. Methods and Results: The protocol used to achieve these objectives was based on a newly published method specifically designed to test wipes. Alcohol impregnated wipes performed better at reducing microbial bioburden than the alcohol spray/dry wipe applications. Impregnated wipes drastically reduced (1–2 log₁₀ reduction) a small bioburden (approx. 2 log₁₀) of spores of Bacillus subtilis and methicillin‐resistant Staphylococcus aureus from the surface, but failed to remove (<0·2 log₁₀ reduction) Staphylococcus epidermidis. The alcohol spray/dry wipes did not manage to remove (<0·2 log₁₀ reduction) spore or bacterial bioburden from surfaces and was able to transfer some viable micro‐organisms to other surfaces. Both wipe types showed poor antimicrobial efficacy (<1 log₁₀ reduction) against the test bacteria and spores. Conclusions: As far as the authors are aware this is the first time that such a practical study has been reported and our results suggest that the best wipes for surface disinfection in aseptic units are the alcohol (IPA) impregnated wipes when compared with the dry wipes sprayed with alcohol. Significance and Impact of the Study: The impregnated wipes performed better than the dry wipes sprayed with alcohol and should be used for surface disinfection in aseptic units.     

The X-ray Structure of NccX from Cupriavidus metallidurans 31A Illustrates Potential Dangers of Detergent Solubilization When Generating and Interpreting Crystal Structures of Membrane Proteins

The x-ray structure of NccX, a type II transmembrane metal sensor, from Cupriavidus metallidurans 31A has been determined at a resolution of 3.12 Å. This was achieved after solubilization by dodecylphosphocholine and purification in the presence of the detergent. NccX crystal structure did not match the model based on the extensively characterized periplasmic domain of its closest homologue CnrX. Instead, the periplasmic domains of NccX appeared collapsed against the hydrophobic transmembrane segments, leading to an aberrant topology incompatible with membrane insertion. This was explained by a detergent-induced redistribution of the hydrophobic interactions among the transmembrane helices and a pair of hydrophobic patches keeping the periplasmic domains together in the native dimer. Molecular dynamics simulations performed with the full-length protein or with the transmembrane segments were used along with in vivo homodimerization assays (TOXCAT) to evaluate the determinants of the interactions between NccX protomers. Taken as a whole, computational and experimental results are in agreement with the structural model of CnrX where a cradle-shaped periplasmic metal sensor domain is anchored into the inner membrane by two N-terminal helices. In addition, they show that the main determinant of NccX dimerization is the periplasmic soluble domain and that the interaction between transmembrane segments is highly dynamic. The present work introduces a new crystal structure for a transmembrane protein and, in line with previous studies, substantiates the use of complementary theoretical and in vivo investigations to rationalize a three-dimensional structure obtained in non-native conditions.     

Development of a new ultraporous polymer as support in organic synthesis

This paper describes the preparation and post-functionalisation of a new polymeric support based on emulsion-derived foams and called polyHIPEs. The remaining pendant vinylic bonds are easily functionalised by a free radical mechanism. The large pores and channels of this material allow an easy access of the reagent in solution toward the grafted species. PolyHIPE-supported thiol, in the presence of an excess of triethylsilane, showed a good activity and selectivity toward reductive cyclisation of 6-bromohex-1-ene and 1-allyloxy-2-bromobenzene.