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Poly(vinyl chloride) undergoes dechlorination in the presence of triethylsilane (Et 3 SiH) and a catalytic amount of [Cp 2 Zr(NPh 2 )][CH 3 B(C 6 F 5 ) 3 ] (1 b) at 40-80 °C, with up to 91 % efficiency. Stoichiometric reactivity studies conducted on cyclohexyl chloride as a model suggest that 1 b dechlorinates PVC by initial chloride abstraction, followed by hydride transfer to the cationic PVC chain from Et 3 SiH. Consumer items such as pipe fitting, vinyl disc or electric cable insulation undergo either dechlorination or hydrosilylation of the carbonyl-containing copolymer (polyvinyl acetate) or plasticizer (phthalate)., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Identifying the mechanisms maintaining population structure in marine fish species with more than a single dispersing life stage is challenging because of the difficulty in tracking all life stages. Here, a two-stage otolith microchemistry approach to examining life-stage movement was adopted, tracking a year-class from the juvenile to adult stage and inferring larval sources from clustering, in order to consider the mechanisms maintaining population structuring in North Sea cod. Clustering of near-core chemistry identified four clusters, two of which had either a southern or northern affinity and were similar to juvenile edge chemistry. The other two clusters, common to the central North Sea, had intermediate chemical composition and may have reflected either larval mixing in this region or a lack of geographic heterogeneity in the elemental signature. From the comparison of whole juvenile and the corresponding component of adult otoliths, adults from the southern North Sea mostly recruited from adjacent nursery grounds. In contrast, many adults in the northern North Sea had a juvenile chemistry consistent with the Skagerrak and juveniles from the northern Skagerrak site had a near-core chemistry consistent with the northern North Sea. Similarities in otolith chemistry were consistent with retention of early life stages at a regional level and also juvenile and adult fidelity. The links between the northern North Sea and Skagerrak indicate natal homing, which when considered in the context of genetic evidence is suggestive of philopatry. The approach used here should be useful in exploring the mechanisms underlying population structuring in other species with multiple dispersive life stages and calcified hard parts.

Although numerous studies have demonstrated the key role of bacterial diversity in soil functions and ecosystem services, little is known about the variations and determinants of such diversity on a nationwide scale. The overall objectives of this study were i) to describe the bacterial taxonomic richness variations across France, ii) to identify the ecological processes (i.e. selection by the environment and dispersal limitation) influencing this distribution, and iii) to develop a statistical predictive model of soil bacterial richness. We used the French Soil Quality Monitoring Network (RMQS), which covers all of France with 2,173 sites. The soil bacterial richness (i.e. OTU number) was determined by pyrosequencing 16S rRNA genes and related to the soil characteristics, climatic conditions, geomorphology, land use and space. Mapping of bacterial richness revealed a heterogeneous spatial distribution, structured into patches of about 111km, where the main drivers were the soil physico-chemical properties (18% of explained variance), the spatial descriptors (5.25%, 1.89% and 1.02% for the fine, medium and coarse scales, respectively), and the land use (1.4%). Based on these drivers, a predictive model was developed, which allows a good prediction of the bacterial richness (R2adj of 0.56) and provides a reference value for a given pedoclimatic condition.

Throughout an organism's early development, variations in physiology and behaviours may have long lasting consequences on individual life histories. While a large part of variation in critical life-history transitions remains unexplained, a significant proportion may be caused by early gender effects as part of gender-specific life histories shaped by sexual selection. In this study, we investigated the presence of early gender effects on the timing of emergence from gravel and the energetic status of brown trout (Salmo trutta) early stages. To investigate this question, individual measures of emergence timing, metabolic rate and energetic content were coupled for the first time with the use of a recent genetic marker for sdY (sexually dimorphic on the Y-chromosome), a master sex-determining gene. Our results show that gender does not influence the energetic content of emerging juveniles or their emergence timing. These findings suggest that gender differences may appear later throughout salmonid life history and that selective pressures associated with the critical period of emergence from gravel may shape early life-history traits similarly in both males and females.

Poly(L-lysine) (PLL) dendrigrafts (DGLs) are arborescent biosynthetic polymers of regular and controlled structures. They have specific properties such as biocompatibility and non-immunogenicity, and their surface density of NH2 functions can be easily modified and therefore appears as a powerful tool for the functionalization of hydrophobic polymers used in the context of tissue engineering. In this study, we evaluated several criteria of human skin fibroblasts when cultured with DGL of generations 2, 3 and 4, with linear PLL polymer as reference. In aqueous phase, DGLs and PLL displayed a similar cytotoxicity towards fibroblasts. Plastic culture plates grafted with DGLs were further characterized as homogeneous surfaces by atomic force microscopy and surface characterization by amino density estimation by colorimetric assay. Proliferation of fibroblasts was increased when cultured onto PLL and DGLs monolayers when compared with crude plates. Cellular adhesion was increased by 20% on DGLs in comparison to PLL. Integrin α5 subunit protein expression level was increased after 48 h of culture on DGLs, in comparison to control or PLL-coated surfaces. The presence of DGLs did not lead to overexpression or activation of matrix metalloproteinases 2 and 9. Finally, fibroblasts adhesion was increased by 40% on poly-(lactic-co-glycolic acid) matrices functionalized with DGLs when compared to PLL. Overall, these features make DGL promising candidates for the surface engineering of biomaterials in tissue engineering.

Energetic status can be defined as the interaction between energy stores and metabolic rate. In salmonids, it is variable and influences the timing of emergence, and therefore may have strong effects on both juvenile and maternal fitness. The aim of this study is to (i) describe the ontogeny of energy use for different brown trout clutches to understand how such a variability of energetic status is developed at the end of incubation and (ii) to estimate maternal influences over offspring physiological processes. Using individual measures of total mass and metabolism throughout ontogeny combined with a hierarchical Bayesian modeling approach, we successfully described clutch-specific (i) metabolic trajectories, (ii) use of yolk resources and the building of new tissues throughout ontogeny. Our results show that females laying large eggs have offspring with lower metabolic costs and higher yolk conversion efficiencies. Females also influence within clutch variance of metabolic and yolk consumption rates leading to potential developmental variations. These results are discussed with regard to their consequences on early life history through the critical period of emergence., (© 2012 WILEY PERIODICALS, INC.)

Ontogenetic niche shift should occur when the ratio of growth opportunities to mortality risk becomes higher in the subsequent habitat. While most studies have focused on size to understand the timing of these shifts, an endogenous factor like energetic status (interaction between energy available and energy requirements) appears as a natural candidate to integrate and analyze the growth trade-off between habitats. In this study, we measure energetic content and metabolic rate of individual brown trout (Salmo trutta) fry at emergence from gravel to investigate the influence of energetic status on the timing of this critical ontogenetic niche shift. In addition, as offspring energetic status is subject to parental effects, we examine how females could maximize their own fitness by influencing offspring emergence timing. Our results demonstrate that emergence from gravel is influenced by energetic status. Individuals that emerge first have a higher energetic content but deplete it faster because of a higher metabolic rate. We also find that female fecundity is positively related to emergence period duration. Moreover, our results suggest that females may decrease kin competition during the critical period of emergence by influencing the energetic status of offspring, thus, maximizing their own fitness. Our results help elucidate the mechanisms underlying early ontogenetic niche shifts in juvenile fish and suggest reasons why maternal investment can be so variable within populations.

Routine metabolic rate (oxygen consumption) of individual eggs and larvae of brown trout (Salmo trutta) originating from different families were monitored from fertilisation to the onset of emergence by means of flow through micro-respirometry. This measuring system revealed an accurate tool to measure oxygen consumption on small organisms at the individual level, and daily consumption proved to be very stable. The mass-specific metabolic rate remained low from fertilisation to hatching, and then increased quickly until the age of emergence. A Bayesian modelling approach was used to adequately infer maternal effects on metabolic rate dynamics all along the development period. Substantial differences were found between families, affecting average metabolic rate as well as intra-family variance. That is, offspring originating from different females may have different energetic needs at emergence from gravel. Moreover, between siblings, variability in metabolic rate is also under the influence of maternal effects. Implications of this metabolic rate variability are discussed with regard to life history strategies and early behaviours.