Regulation of gene expression

A variety of anthropogenic xenobiotics bring about a considerable increase in pollution and the progressive degradation of marine ecosystems. Certain of these chemical compounds are suspected or well-known to interfere with endocrine systems; so called endocrine disrupting compounds, EDCs have multiple modes of action: binding to hormone receptors, modification of the intrinsic natural hormone concentrations by acting on their synthesis, storage, transport, metabolism and secretion. Whatever their modes of action, the deleterious effects of the EDCs upon the endocrine system of fishes are notable: thyroid dysfunction, the appearance of developmental and behavioural anomalies, incomplete development of genital organs, a reduction in fecundity, the appearance of « imposex »... Even low concentrations of EDCs in marine environments represent a significant threat to wildlife (e.g. feminization of marine species and vice versa) and ultimately to human health. In order to complete current knowledges about the molecular mecanisms and effects of EDCs, this project was designed to study the impact of six substances, with distinct endocrine activities (E2, 11KT, tamoxifen, cyproterone acetate, BaP and 4NP) in European sea bass (Dicentrarchus labrax L.). Various studies about EDC impact in fish are performed using both traditional biomarkers and biochimical analysis: detoxification enzyme status, plasma hormone concentrations, immuno-assays... Current studies are interested in molecular responses using of cDNA microarrays. The purpose of the « Quality Fish » project is to investigate the feasability of applying array technology as a monitoring tool for assessing the presence of endocrine compounds in D. Labrax. The results obtained with these new pollutants will allow to re-design a set of genes (more complete) and this new genetic signature could be extrapolated to common mediterranean species.Projet approved in February 2008