Development of a new low density stress response microarray STREM

Development of a new low density stress response microarray to evaluate biological effects of contaminants in Mytilus sp: laboratory validation. Background: Despite the increasing use of mussels in environmental monitoring, their genome and gene functions remain weakly explored. Recently several cDNA microarrays were proposed in Mytilussp, however partial putatively identified transcripts are provided rendering very difficult the generation of robust transcriptional responses in term of pathwaysidentification. In this study we developed a new medium density oligonucleotide microarray with 476 probes covering the same number of well identified genes representing 16 Biological processes at cellular and tissue levels among the most important in mussel’s response to stress (Lysosomal activity, DNA Metabolism, Translation, Mitochondrial activity, Carbohydrate metabolism, Heat choc response, Oxydatif stress, Proteolysis, Phase I and II detoxification, Metal resistance, Endocrine disruptors, Endocytosis, Macrophage, Pumps, Cytoskeleton, Adhesion to substrate). Our new platform STREM (STress Response Microarray in Mytilussp) consists of eight sub-arrays with 3 repetitions for each target in each sub-array. To assess the potential use of the new array, we tested the effect of three Benzo[a]pyren (B[a]P) concentrations, a relevant environmental contaminants in two mussel’s tissues; gills and digestive gland. Our data provided clues about the higher sensitivity of the new array. Moreover transcriptional data were confirmed using Q-RT-PCR and the possible implication in biological role by conventional biomarkers of stress (oxidative stress biomarkers) as well as immune-histochemical analysis (Tubulin). Digestive gland and gills tissue from individual animals in different experimental conditions were analyzed in a complete loop design. Dual color competitive hybridizations (Control vs BaP 5µg/L vs 50µg/L and 100 µg/L ). Single individuals. Four biological replicates. two replicates per array.