Effets endocriniens des contaminants en milieu marin

This report presents the state of art of endocrine disruption aspects in ecotoxicology. Some contaminants of the aquatic environment are able to mimic female fish hormones and thereby cause inappropriate feminisation of male fish. This feminisation involves artificial induction and emergence of ovotestis in male (oestrogenic disruption). Natural and synthetic oestrogenic hormones and several contaminants (alkylphenols, PCBs, phtalates and some pesticides) are already known to cause widespread feminisation of male. Two different types of analysis can be performed to detect oestrogenics effects. Immunochemical analysis of plasma (Enzyme-linked immunosorbent assay ELISA and radioimmuno assay RIA) shows that xenoestrogens induce vitellogenin and protein zona radiata in male fish. These two proteins can be used as biomarkers in the detection of effects. The sexual reversion in male can also be detected by histological observation of testicular tissue. Together with this bibliographic study, research laboratory work was also conducted. Field studies on three males of the flounder (Platichthys flesus) in the Loire estuary sampled after the reproductive period have shown no effects on the histology of testes. Two histological methods were tested and revealed that the classical method of paraffin inclusion led better results in terms of gonadal observation. The method using cryomicrotome from frozen gonads still needs to be optimized.