Étude de la formation d'adduits et de 8-oxodguo à l'ADN de moule, Mytilus sp: perspectives d'utilisation dans le milieu marin en tant que biomarqueurs de génotoxicité des hydrocarbures aromatiques polycycliques

In the aim to develop biomarkers of genotoxicity for the biomonitoring of the marine environment,the formation of DNA adducts and oxidized DNA bases was studied for the sentinel organism, Mytilus sp, following exposure to B[a]P via the trophic supply. DNA adducts and 8-oxo-7,8-dihydro-2'-désoxyguanosine (8-oxodGuo) were respectively measured by 32P post-labeling technique and high performance liquid chromatography coupled to electrochemical detection. The developped model of exposure was validated for the realisation of toxicological studies in Mytilus sp. The bioavailability of B[a]P for the exposed organisms and its biotransformation resulted in variations in most of the measured enzymatic biomarkers of exposure. Such an exposure allowed the expression ofB[a]P genotoxic effects in mussels. In mussel gills and digestive gland, the observation of correlations between total DNA adduct level and both exposure time and B[a]P concentration in whole mussel tissues was in favour of the proposal of DNA adducts as biomarkers of PAH genotoxicity. For the studied marine invertebrate, gills appeared as a target tissue for DNA adduct formation. In the field, DNA adduct measurement allowed the discrin1Ïnation of the different sampling sites in accordance to their presumed level of contan1Înation to genotoxic compounds. 8-oxodGuo appeared as a potential biomarker of genotoxicity only in the digestive gland, identified as a target tissue of oxidative stress in the mussel. In the field, observation of correlations between 8-oxodGuo level and response of the measured biomarkers of the oxidative stress was in favour of further investigations.