Comparative embryotoxicity and genotoxicity of the herbicide diuron and its metabolites in early life stages of Crassostrea gigas: implication of reactive oxygen species production

• Published in: Aquatic Toxicology
• Main Authors: Behrens, Daphne, Rouxel, Julien, Burgeot, Thierry, Akcha, Farida
• Other Authors: Laboratoire d'Écotoxicologie (LEX), Biogéochimie et Ecotoxicologie (BE), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: [SDV]Life Sciences [q-bio]; Pacific; Crassostrea gigas; Pacific oyster
• Online Access: https://hal.science/hal-04200814; https://doi.org/10.1016/j.aquatox.2016.04.003

Herbicides are one of the major classes of pollutants contaminating coastal waters over the world. Among them, diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) is a phenylurea herbicide frequently detected in oyster-producing area, known to be toxic for this important exploited non-target species. With the aim to investigate the mechanisms by which diuron displays its toxicity in oyster, the implication of both biotransformation and oxygen reactive species (ROS) production was studied considering embryotoxicity and genotoxicity as endpoints. Comparative embryotoxicity and genotoxicity of diuron and its main metabolites (DCPMU, DCPU and 3,4-DCA) were thus studied on oyster larvae by the embryo-larval bioassay on D larvae and the comet assay on trochophore larvae, respectively. Exposures were also performed in presence and absence of known ROS scavenger compounds − ascorbic acid and N-acetylcysteine, to evaluate the involvement of oxyradicals in the toxic responses. In the case of diuron, the production of ROS on exposed oyster larvae was also measured using 2',7'-dichlorodihydrofluorescein diacetate as a probe for flow cytometric analysis.The results we obtained showed the embryotoxicity and genotoxicity of diuron and its metabolites in early life stages of the Pacific oyster. For concentrations ranging from 0.05 to 0.5 μg.L−1, diuron appeared significantly more embryotoxic than DCPMU and DCPU (p < 0.001). Embryotoxicity decreased with diuron metabolism as follows: diuron ≥ DCPMU = DCPU, highlighting that biotransformation can constitute a true detoxication pathways in oyster larvae by decreasing the toxicity of the parent compound. In the opposite, no difference was observed between diuron and its metabolites concerning larval development when considering a lower and more environmentally realistic range of concentrations (0.002 to 0.050 μg.L−1). 3,4-DCA was the only compound that did not show any sign of embryotoxicity, even at concentrations up to 5 μg.L−1. Concerning genotoxicity, no significant difference ...