Mise en évidence de protéines révélant une réponse au stress adaptative divergente entre les espèces Dreissena polymorpha et Dreissena rostriformis bugensis

International audienceZebra mussels Dreissena polymorpha, are bivalve molluscs used in ecotoxicology, as a sentinel species with, among other things, a strong bioaccumulation capacity. The quagga mussel, Dreissena rostriformis bugensis, has more recently colonized Western Europe. Also invasive, it competes with zebra mussels for habitats and, in some areas, has completely replaced it. Its use as a sentinel species is envisaged but requires understanding the mechanisms involved during the adaptive stress response and comparing them to those of the zebra mussel, which are better characterized. With this in mind, an exposure of the two species to a classical contaminant was performed to compare their responses. The individuals were exposed to a concentration of 100 μg / L of cadmium for 7 days, and then the gill proteins were separated by two-dimensional electrophoresis and the variable abundance proteoforms were identified by mass spectrometry. The functional analysis reveals promising elements for the study of the adaptive response in both species. A difference of expression of actors of the energy metabolism pathways points a physiological difference, with a reallocation of energy as well as the appearance of truncated proteins.Les moules zébrées, Dreissena polymorpha sont des mollusques bivalves utilisés en écotoxicologie comme espèces sentinelles du fait, entre autre, de leur capacité de bioaccumulation. La moule quagga, Dreissena rostriformis bugensis, a colonisé plus récemment l'Europe occidentale. Egalement invasive, elle est en compétition avec la moule zébrée pour les habitats et, dans certaines zones, l'a complètement remplacée. Son utilisation en tant qu'espèce sentinelle est envisagée mais nécessite de comprendre les mécanismes mis en jeu au cours de la réponse adaptative au stress et de les comparer à ceux de la moule zébrée, mieux caractérisés. Dans cette optique, une exposition des deux espèces à un contaminant classique a été réalisée afin de comparer leurs réponses. Les individus ont été exposés à une concentration de 100μg/L de cadmium pendant 7 jours, puis les protéines des branchies ont été séparées par électrophorèse bidimensionnelle et les protéoformes d'abondance variable ont été identifiées par spectrométrie de masse. L'analyse fonctionnelle révèle des éléments prometteurs pour l'étude de la réponse adaptative chez les deux espèces. Une différence d'expression d'acteurs des voies du métabolisme énergétique pointe une différence physiologique, avec une réallocation de l'énergie ainsi que l'apparition de protéines tronquées

Catching Element Formation In The Act

Gamma-ray astronomy explores the most energetic photons in nature to address some of the most pressing puzzles in contemporary astrophysics. It encompasses a wide range of objects and phenomena: stars, supernovae, novae, neutron stars, stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays and relativistic-particle acceleration, and the evolution of galaxies. MeV gamma-rays provide a unique probe of nuclear processes in astronomy, directly measuring radioactive decay, nuclear de-excitation, and positron annihilation. The substantial information carried by gamma-ray photons allows us to see deeper into these objects, the bulk of the power is often emitted at gamma-ray energies, and radioactivity provides a natural physical clock that adds unique information. New science will be driven by time-domain population studies at gamma-ray energies. This science is enabled by next-generation gamma-ray instruments with one to two orders of magnitude better sensitivity, larger sky coverage, and faster cadence than all previous gamma-ray instruments. This transformative capability permits: (a) the accurate identification of the gamma-ray emitting objects and correlations with observations taken at other wavelengths and with other messengers; (b) construction of new gamma-ray maps of the Milky Way and other nearby galaxies where extended regions are distinguished from point sources; and (c) considerable serendipitous science of scarce events -- nearby neutron star mergers, for example. Advances in technology push the performance of new gamma-ray instruments to address a wide set of astrophysical questions.Comment: 14 pages including 3 figure

Variation in variance means more than mean variations: What does variability tell us about population health status?

International audienceIn environmental science, the variability of biological responses in natural or laboratory populations is a well known and documented phenomenon. However, while an extensive literature aims to explain and understand the origin of variability, few try to use it as a demonstration of the population's response facing a stress. We propose here a theoretical framework that explores various patterns of variability both within and among populations, and seeks methods useful in bioevaluation methodologies. We also introduce the concept of “ecotoxicological niche” to characterize the ability of a population to endure contamination

Long-term monitoring of benthic invertebrate communities in a highly invaded ecosystem, the Mosel River

International audienceExotic species, once established in the recipient ecosystem, can established and, in some cases, become invasive. However, long-term monitoring of invaded ecosystems remains quite rare, while it’s the unique method to describe and understand how local communities adapt -or not- to the continuous fluxes of new exotic invasive species, and how these exotic species manage to persist within these local communities. Some species’ proliferations can indeed be only transitory, with sometimes their disappearance, either naturally or through the interaction with a newcomer. The Mosel River, located in North-eastern France, is studied since 1994 with the same protocol to investigate benthic macroinvertebrates communities. It is one of the main corridors for aquatic invasions in France, with near to 20 exotic invertebrate species, mainly molluscans and crustaceans, established within its biocenosis. Benthic communities were investigated 13 times between 1994 and 2021, by dredge-sampling from a boat at four stations in spring and/or autumn. Our results evidenced strong modifications of community composition over years, while structure index showed a come-back of 2021 structure to that identified in 1996, that is however not a pre-invasion state. We also evidenced that the species richness did not increase with the increasing number of exotic species, suggesting that newcomers took the place of species already there, and did not colonize a vacant niche. The investigation of trophic groups showed communities strongly dominated by parasites and predators in 1994, filter-feeder and detritivore from 1996 to 2001, and a stabilization of the relative abundance of the different groups in recent years. Such observation strategies need to be developed in other systems for a better description of exotic species dynamic, especially now that global change is potentially accelerating migration of species

Depict the mechanisms governing parasite communities within Dreissena polymorpha: stochastic, biotic interaction or driven by contamination?

International audienc

Fiches pratiques pour l'utilisation des dreissènes en bioévaluation

Le rapport est constitué de 7 fiches techniques :FICHE 1 : PROSPECTION DES DREISSENESFICHE 2 : IDENTIFICATION DES DREISSENESFICHE 3 : PRELEVEMENT ET DISSECTIONFICHE 4 : MESURE DE L'INDICE DE CONDITIONFICHE 5 : MESURE DU TAUX DE FILTRATIONFICHE 6 : MESURE DES BIOMARQUEURSFICHE 7 : CALCUL DE L'IB

Variabilité saisonnière des biomarqueurs chez les bivalves du genre Dreissena et implications pour le biomonitoring

National audienc

Multi-biomarker evaluation of a multi-stress exposure in two freshwater bivalves

International audienc

Biomarker versus environmental factors: seasonal variations and modelling of multixenobiotic defence (MXD) transport activity in transplanted zebra mussels

International audienceThe occurrence of biomarker temporal variations linked to environmental factors makes it difficult to distinguish the specific effect of pollution. The present work aims to investigate the seasonal variations of the transport activity of the multixenobiotic defence (MXD), which is used as a biological tool for the monitoring of pollution in aquatic ecosystems. The MXD transport activity was monitored monthly from August 2001 to October 2002 in zebra mussels (Dreissena polymorpha) transplanted to three sites in the Moselle River. The ‘efflux method’ was used to evaluate functional activity of MXD by assessing rhodamine B efflux with or without an inhibitor (verapamil). Environmental parameters were provided by a French regulatory agency (Water Agency) that monitors river water quality. The results of a principal components analysis describe the seasonal cycle of water characteristics and demonstrate that MXD activity is subjected to significant temporal variations. These data were described with a generalised linear model that enables it to link MXD variability to the seasonal variations of environmental parameters such as temperature or levels of organic contamination. This work proposes a modelling approach and highlights that the occurrence of seasonal variations in MXD response has to be taken into account in the interpretation of in situ monitoring studies