Effects of benzo[a]pyrene on DNA damage and histological alterations in gonad of scallop Chlamys farreri.

To investigate the biological impact of polycyclic aromatic hydrocarbons (PAHs) on reproductive system, scallops Chlamys farreri were continuously exposed to benzo[a]pyrene (BaP) (0.5, 3, 10microgL(-1)) during 15 days. DNA damage and histological alterations were examined in female gonad. DNA strand break levels significantly increased after 12h exposure, and remained high and significantly different from control values until the end of the exposure. In the ovaries of the scallops exposed to 10microgL(-1) BaP for ten days, histological analysis showed that the cytoplasts of the oocytes in the outer layer of the ovaries became sparse, and the nuclear membranes were obscure. Damaging effects on ovaries and oocytes were more severe after 15 days exposure. Degenerating oocytes increased and the connective tissue of the ovary envelops became loose. Electron microscopic examination revealed ultrastructural aspects of degenerating oocyte and degenerated oocyte after 15 days exposure.