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Corbicula fluminea gene expression modulated by nCeO2 exposure and salinity
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International audience. Nanotechnology interest has considerably grown during last decades andnanoproducts are now part of our everyday life. Nanoparticle (NP) concentrationsin natural environment are not yet known but releases during their life cycle are toconsider. NP harmful effects have already been demonstrated on freshwater andmarine species but their potential toxicity at more realistic low exposureconcentration is still not well studied. Cerium dioxide nanoparticles (nCeO2) arelisted in OECD priority list of manufactured nanomaterials for their assessmentbecause of their large production making them available for widespread uses indaily products. They are used in different fields such as automotive or optic. Severalstudies highlighted that nCeO2 impact organism’s physiology by affectingoxidative defenses and cellular membrane stability while gene expression studiesremain still scarce and especially among non-sequenced organisms.\nThe aim ofthe present work was to evaluate gene expression disturbance occurring in C.fluminea, a widespread freshwater bivalve, exposed during 28 days under indoormesocosm to multistress conditions. Two salinities (1.5 and 15 PSU) were appliedto cover a range of salinity from the continent to the estuaries and three NPs wereselected in order to have both standardized and commercial NPs but also to mimicchanges occurring after NP uses. Two studies were done on variation of 12 geneexpression by RT-qPCR in gills and digestive gland according to the exposureconditions and time. Global profile of gene expression responses are clearlydifferent according to the salinity and both organs selected were responding to NPcontamination. Results obtained for NPs extracted from commercial product havehighlighted the need of further studies using consumer available NPs. The secondstudy was about comparing expression level of the 12 selected genes in both organsafter 28 days in control organisms. Interestingly, tissues expression gene analysisrevealed strong differences of expression level (>2 fold) for some genes in gillscompared to digestive gland regardless to salinity. This work followed expressionof 12 genes that showed expression variation according to medium salinity, organor nCeO2. Studying gene expression changes is an earlier way to detectcontamination impact. Genome sequencing of C. fluminea should allow to analyzemore gene expression involved in other molecular pathway potentially impacted.
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