Recherche d'effets biologiques de l'atrazine sur hémocytes d'huître creuse, Crassostrea gigas, in vivo et in vitro

In the last decades, shellfish farming and in particular ostreiculture have developed in a significant way in France. Marennes-Oleron (Charente-Maritime) basin is the first French producer of oysters. But this area is also subjected to many recurring pollution, brought mainly by the Charente river. The recrudescence using of herbicides in agriculture including atrazine implies the transfer towards the aquatic environment of new pollutants in estuarine areas. Moreover industrial rejections bring many heavy metals in these same estuarine areas. It is appropriate of wondering on harmful effects of all these pollutants on the animals living in these areas, particularly oysters. Bivalve molluscs have been postulated as ideal indicator organisms because of their way of life. They filter large volumes of seawater and may therefore concentrate contaminants within their tissues. Moreover, the development of techniques allowing the analysis of the impact of such compounds on bivalve biology could lead to the installation of diagnostic tools adapted to the follow-up of the transfer of pollutants towards the estuarine areas. In this context, the influence of atrazine on the mechanisms of defence developed by Japanese oyster, Crassostrea gigas, species primarily high in the basin of Marennes-Oléron, was tested. Atrazine was tested in vitro on the defence cells of the organism, haemocytes, with several concentrations (2,20 and 200 mg.L-1) and several times of contact (4 and 24 hours). Atrazine was also tested in in vivo experiments : oysters have been in contact with atrazine (0.01 and 0.1 mg.L-1) for two months. In both experiments types, haemocytes were analyzed by flow cytometry; viability and cellular activities (phagocytosis activity, hydrolytic enzymes, cell cycle) were monitored. The results show that atrazine induce no mortality on the haemocytes under the conditions tested in vitro. But experiments carried out in vivo allowed us to shiw a possible genotoxic effect of this pollutant (increase of number of dividing cells).