Influence of fillers on mechanical properties of ATH filled EPDM during ageing by gamma irradiation

International audienceThe presence of a significant content of fillers accelerates the degradation of ATH filled EPDM subjected to gamma irradiation at room temperature. Above the melting temperature of the EPDM, this induces a decrease in the apparent mechanical reinforcement of the fillers. This also promotes de-cohesion mechanisms which leads to an increase in the strain at break with irradiation dose. It is not clear whether the use of a filler treatment attenuates this accelerating effect or not; however, part of this treatment remains efficient at a high dose and seems also to delay but not suppress the occurrence of de-cohesion mechanisms at large strain. Moreover, at room temperature, i.e. below the melting temperature, all the consequences of ageing by gamma irradiation are strongly attenuated by the presence of a semicrystalline microstructure, the morphology of which is not too strongly modified by irradiation. (C) 2010 Elsevier Ltd. All rights reserved

Natural hybridization between pen shell species: Pinna rudis and the critically endangered Pinna nobilis may explain parasite resistance in P. nobilis

Recently, Pinna nobilis pen shells population in Mediterranean Sea has plummeted due to a Mass Mortality Event caused by an haplosporidian parasite. In consequence, this bivalve species has been included in the IUCN Red List as “Critically Endangered”. In the current scenario, several works are in progress to protect P. nobilis from extinction, being identification of hybrids (P. nobilis x P. rudis) among survivors extremely important for the conservation of the species. Morphological characteristics and molecular analyses were used to identify putative hybrids. A total of 10 individuals of each species (P. nobilis and P. rudis) and 3 doubtful individuals were considered in this study. The putative hybrids showed shell morphology and mantle coloration intermingled exhibiting both P. nobilis and P. rudis traits. Moreover, the analyses of 1150 bp of the 28S gene showed 9 diagnostic sites between P. rudis and P. nobilis, whereas hybrids showed both parental diagnostic alleles at the diagnostic loci. Regarding the multilocus genotypes from the 8 microsatellite markers, the segregation of two Pinna species was clearly detected on the PCoA plot and the 3 hybrids showed intermediate positions. This is the first study evidencing the existence of hybrids P. nobilis x P. rudis, providing molecular methodology for a proper identification of new hybrids. Further studies testing systematically all parasite-resisting isolated P. nobilis should be undertaken to determine if the resistance is resulting from introgression of P. rudis into P. nobilis genome and identifying aspects related to resistance.En prens

Genetic homogeneity of the critically endangered fan mussel, Pinna nobilis, throughout lagoons of the Gulf of Lion (North‑Western Mediterranean Sea)

The fan mussel, Pinna nobilis, endemic to the Mediterranean Sea, is a critically endangered species facing mass mortality events in almost all of its populations, following the introduction of the parasite Haplosporidium pinnae. Such a unique pandemic in a marine organism, which spreads rapidly and with mortality rates reaching up to 100%, could lead to the potential extinction of the species. Only few regions, involving lagoon habitats, remain healthy throughout the entire Mediterranean Sea. This study describes the genetic structure of P. nobilis across the Gulf of Lion, including confined locations such as lagoons and ports. A total of 960 samples were collected among 16 sites distributed at 8 localities, and then genotyped using 22 microsatellite markers. Genetic diversity was high in all sites with mean allele numbers ranging between 10 and 14.6 and with observed heterozygosities (Ho) between 0.679 and 0.704. No genetic differentiation could be identified (FST ranging from 0.0018 to 0.0159) and the percentages of related individuals were low and similar among locations (from 1.6 to 6.5%). Consequently, all fan mussels, over the entire coastline surveyed, including those in the most geographically isolated areas, belong to a large genetically homogeneous population across the Gulf of Lion. Considering the ongoing mass mortality context, this result demonstrates that almost all of the genetic diversity of P. nobilis populations is still preserved even in isolated lagoons, which might represent a refuge habitat for the future of the species.En prensa2,92

Investigating population dynamics from parentage analysis in the highly endangered fan mussel Pinna nobilis

Understanding dispersal patterns is a major focus for conservation biology as it influences local survival and resilience in case of local disturbance, particularly for sessile species. Dispersal can be assessed through parentage analyses by estimating family structure and self-recruitment. This study documents the family structure of a pelagic spawner, Pinna nobilis, which is facing a major crisis that threatens its survival as most of its populations have been decimated by a parasite, Haplosporidium pinnae. In this context, we focused on a single population (Peyrefite, Banyuls-sur- mer, France) where 640 individuals were sampled in 2011, 2015, and 2018 and genotyped for 22 microsatellite markers. Genetic diversity was high and homogeneous among years, with mean allele numbers ranging between 13.6 and 14.8 and observed heterozygosities (Ho) between 0.7121 and 0.7331. Low, but significant, genetic differentiations were found between 2011–2015 and 2015–2018. A parentage analysis described 11 clusters, including one prevailing, and revealed that 46.9% of individuals were involved in half-sib relationships, even between years, suggesting that source populations were recurrent year after year. There were few individuals resampled between years (30 in 2015 and 14 in 2018), indicating a rapid turnover. Considering the large number of half-sib relationships but the low number of relations per individual, we conclude that P. nobilis exhibit homogeneous reproductive success. Self-recruitment was not detected, making this population highly vulnerable as replenishment only relies on connectivity from neighboring populations. In the context of the pandemic caused by H. pinnae, these results will have to be considered when choosing a location to reintroduce individuals in potential future rescue plans.En prensa

Ecology, Biology and Genetics of <em>Millepora</em> Hydrocorals on Coral Reefs

Coral reefs are one of the most productive and diverse ecosystems on Earth. However, climate warming is occurring at an unprecedented rate and has negatively affected coral reefs worldwide. Evaluating the life history of reef-building species carries important implications for coral reef conservation. This chapter examines the taxonomy, biogeography, ecology, symbiosis, morphology and reproductive biology of Millepora hydrocorals, an important but relatively unstudied component of coral reefs. An emphasis is also placed on the influence of variable reef environments on Millepora life history traits, providing a fascinating opportunity to study the interplay between ecology and evolution. Special attention is given to ecological and evolutionary benefits of asexual versus sexual reproduction in the maintenance of genetic and phenotypic diversity. Lastly, this chapter discusses whether life-history strategies of Millepora hydrocorals and tolerance to different stressors can influence their ability to adapt and survive to future climate change, and other natural and anthropogenic disturbances

Chronic pulmonary fibrosis alters the functioning of the respiratory neural network

Some patients with idiopathic pulmonary fibrosis present impaired ventilatory variables characterised by low forced vital capacity values associated with an increase in respiratory rate and a decrease in tidal volume which could be related to the increased pulmonary stiffness. The lung stiffness observed in pulmonary fibrosis may also have an effect on the functioning of the brainstem respiratory neural network, which could ultimately reinforce or accentuate ventilatory alterations. To this end, we sought to uncover the consequences of pulmonary fibrosis on ventilatory variables and how the modification of pulmonary rigidity could influence the functioning of the respiratory neuronal network. In a mouse model of pulmonary fibrosis obtained by 6 repeated intratracheal instillations of bleomycin (BLM), we first observed an increase in minute ventilation characterised by an increase in respiratory rate and tidal volume, a desaturation and a decrease in lung compliance. The changes in these ventilatory variables were correlated with the severity of the lung injury. The impact of lung fibrosis was also evaluated on the functioning of the medullary areas involved in the elaboration of the central respiratory drive. Thus, BLM-induced pulmonary fibrosis led to a change in the long-term activity of the medullary neuronal respiratory network, especially at the level of the nucleus of the solitary tract, the first central relay of the peripheral afferents, and the Pre-Bötzinger complex, the inspiratory rhythm generator. Our results showed that pulmonary fibrosis induced modifications not only of pulmonary architecture but also of central control of the respiratory neural network

Chaotic genetic structure and past demographic expansion of the invasive gastropod Tritia neritea in its native range, the Mediterranean Sea

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Boissin, E., Neglia, V., Baksay, S., Micu, D., Bat, L., Topaloglu, B., Todorova, V., Panayotova, M., Kruschel, C., Milchakova, N., Voutsinas, E., Beqiraj, S., Nasto, I., Aglieri, G., Taviani, M., Zane, L., & Planes, S. Chaotic genetic structure and past demographic expansion of the invasive gastropod Tritia neritea in its native range, the Mediterranean Sea. Scientific Reports, 10(1), (2020): 21624. doi:10.1038/s41598-020-77742-3.To better predict population evolution of invasive species in introduced areas it is critical to identify and understand the mechanisms driving genetic diversity and structure in their native range. Here, we combined analyses of the mitochondrial COI gene and 11 microsatellite markers to investigate both past demographic history and contemporaneous genetic structure in the native area of the gastropod Tritia neritea, using Bayesian skyline plots (BSP), multivariate analyses and Bayesian clustering. The BSP framework revealed population expansions, dated after the last glacial maximum. The haplotype network revealed a strong geographic clustering. Multivariate analyses and Bayesian clustering highlighted the strong genetic structure at all scales, between the Black Sea and the Adriatic Sea, but also within basins. Within basins, a random pattern of genetic patchiness was observed, suggesting a superimposition of processes involving natural biological effects (no larval phase and thus limited larval dispersal) and putative anthropogenic transport of specimens. Contrary to the introduced area, no isolation-by-distance patterns were recovered in the Mediterranean or the Black Seas, highlighting different mechanisms at play on both native and introduced areas, triggering unknown consequences for species’ evolutionary trajectories. These results of Tritia neritea populations on its native range highlight a mixture of ancient and recent processes, with the effects of paleoclimates and life history traits likely tangled with the effects of human-mediated dispersal.This project was funded by the European FP7 CoCoNet project (Ocean.2011-4, grant agreement #287844) and we are grateful to the whole CoCoNET consortium. We are grateful to the following people for their critical help with logistics and field work ‘Antheus srl (Lecce, Italy)’; S Bevilacqua, G Guarnieri, S Fraschetti and T Terlizzi (University of Salento, Italy); L Angeletti and M Sigovini (ISMAR, Italy); D Shamrey (IBSS, Sevastopol); A Anastasopoulou, MA Pancucci-Papadopoulou and S Reizopoulou (HCMR, Greece) and E Hajdëri (Catholic University ‘Our Lady of Good Counsel’, Tirana). Thank you to J Almany for English corrections. This is ISMAR-CNR scientific contribution n1987. E Boissin was supported by a European Marie Curie postdoctoral fellowship MC-CIG-618480

The Tara Pacific expedition—A pan-ecosystemic approach of the “-omics” complexity of coral reef holobionts across the Pacific Ocean

Coral reefs are the most diverse habitats in the marine realm. Their productivity, structural complexity, and biodiversity critically depend on ecosystem services provided by corals that are threatened because of climate change effects—in particular, ocean warming and acidification. The coral holobiont is composed of the coral animal host, endosymbiotic dinoflagellates, associated viruses, bacteria, and other microeukaryotes. In particular, the mandatory photosymbiosis with microalgae of the family Symbiodiniaceae and its consequences on the evolution, physiology, and stress resilience of the coral holobiont have yet to be fully elucidated. The functioning of the holobiont as a whole is largely unknown, although bacteria and viruses are presumed to play roles in metabolic interactions, immunity, and stress tolerance. In the context of climate change and anthropogenic threats on coral reef ecosystems, the Tara Pacific project aims to provide a baseline of the “-omics” complexity of the coral holobiont and its ecosystem across the Pacific Ocean and for various oceanographically distinct defined areas. Inspired by the previous Tara Oceans expeditions, the Tara Pacific expedition (2016–2018) has applied a pan-ecosystemic approach on coral reefs throughout the Pacific Ocean, drawing an east–west transect from Panama to Papua New Guinea and a south–north transect from Australia to Japan, sampling corals throughout 32 island systems with local replicates. Tara Pacific has developed and applied state-of-the-art technologies in very-high-throughput genetic sequencing and molecular analysis to reveal the entire microbial and chemical diversity as well as functional traits associated with coral holobionts, together with various measures on environmental forcing. This ambitious project aims at revealing a massive amount of novel biodiversity, shedding light on the complex links between genomes, transcriptomes, metabolomes, organisms, and ecosystem functions in coral reefs and providing a reference of the biological state of modern coral reefs in the Anthropocene

Influence des charges sur l\u27évolution des propriétés mécaniques des EPDM chargés lors de leur vieillissement par irradiation

La compréhension de l\u27évolution des propriétés mécaniques et la détermination de la durée de vie des matériaux en ambiance industrielle est un problème récurrent. Cette question est notamment déterminante dans la mise au point de formulations de polymères utilisés pour la fabrication de câbles électriques employés dans les centrales nucléaires. Ainsi il importe de connaître l\u27évolution de ces matériaux lorsqu\u27ils sont soumis à des conditions de marche normale d\u27une centrale nucléaire. Il existe dans la littérature plusieurs études concernant le vieillissement par irradiation d\u27élastomères non chargés mais l\u27introduction de charges dans le matériau peut avoir des conséquences sur l\u27évolution des propriétés mécaniques lors de leur irradiation. Notre travail a donc porté sur l\u27étude du vieillissement par irradiation des élastomères chargés et l\u27identification de rôle des charges dans les mécanismes de vieillissement. Nos efforts se sont concentrés sur une seule matrice largement utilisée pour ce type d\u27application utilisée pour ce type d\u27application : il s\u27agit de l\u27EPDM norbordène. Les charges sont de d\u27eux types : la silice et les trihydrates d\u27aluminium. leurs surfaces ont été traitées afin de mieux comprendre le rôle des interfaces charges-matrice lors du vieillissement. Afin de déterminer l\u27influence des charges sur les mécanismes de dégradation et sur l\u27évolution des propriétés mécaniques, l\u27évolution dans le temps de ces matériaux chargés ou non a été étudié dans le cadre du vieillissement par irradiation : ils ont été testés et caractérisés à différents niveaux de vieillissement en termes physico-chimique, microstructural et mécanique