REACTIVE OXYGEN SPECIES AND DEFENSE-MECHA NISMS IN MARINE BIVALVES

The main results published on the production of reactive oxygen interm ediates by hemocytes and digestive glands of marine bivalves such as m ussels, oysters or clams have been reviewed and discussed. Mussel and oyster hemocytes respond to appropriate stimuli with a burst of respir atory activity and the generation of reactive oxygen intermediates in a manner resembling the respiratory burst of mammalian phagocytes. How ever, interspecies differences in hemocytes-mediated antimicrobial def ense mechanisms occur since clam hemocytes do not show any increase of reactive oxygen intermediate production upon similar stimulations. He patopancreatic gland of bivalves, as mammalian and fish liver produce reactive oxygen species during the one-electron reduction of xenobioti cs, and mechanistic differences appear between bivalves and mammals. T hus, it appears that, in spite of some interspecies differences, the g eneration of cytotoxic reactive oxygen species is a general protective mechanism of most, if not all, animal species.