PROOXIDANT PROCESSES AND ANTIOXIDANT DEFENSE SYSTEMS IN THE TISSUES OF THE ANTARCTIC SCALLOP (ADAMUSSIUM-COLBECKI) COMPARED WITH THE MEDITERRANEAN SCALLOP (PECTEN-JACOBAEUS)

Antioxidant defences (scavengers, enzymes), pro-oxidant processes (in vitro NAD(P)H-dependent iron/EDTA-mediated hydroxyl radical (. OH) production and susceptibility to lipid peroxidation) were investigated in the tissues of the antarctic scallop Adamussium colbecki (Smith, 1902) compared with a scallop species typical of temperate, mediterranean waters, Pecten jacobaeus L. Levels of free radical scavengers (total glutathione, vitamin E, total carotenoids) and activities of antioxidant enzymes (superoxide dismutase, EC 1.15.1.1.; catalase, EC 1.11.1.6.; glutathione peroxidase, EC 1.11.1.9.) were in the same range in both species and in both were higher in digestive gland than gills, The in vitro potential for . OH production was higher in the digestive gland than the gills for both species, consistent with the former tissue's higher levels of antioxidant defences, Inhibition studies (A, colbecki) indicated the involvement of superoxide anion radical and hydrogen peroxide in . OH formation, The digestive gland of A, colbecki showed a lower susceptibility to 'in vitro' stimulated lipid peroxidation than that of P,jacobaeus, The results are discussed in relation to the adaptation of A, colbecki to extreme Antarctic conditions, including low temperature, high oxygen tension and marked seasonality of food intake, all of which can influence reactive oxygen species formation.