Lysosomal and antioxidant defenses to metals in the Antarctic scallop Adamissiun colbecki

Lysosomal and antioxidant responses were investigated in the Antarctic scallop Adamussium colbecki exposed under laboratory conditions to metals as well as in specimens transplanted from a pristine area to the Bay receiving the discharges of the Italian Base. Exposure to copper and mercury resulted in a significant reduction of lysosomal membrane stability and in the appearance of severe morphological alterations varying from the presence of enlarged lysosomes to the loss of lysosomal structures. More limited effects were observed in Pb-exposed scallops. Moreover, laboratory exposures to Cu and Hg greatly depleted the levels of total glutathione and the activities of catalase and glutathione S-transferases were significantly reduced. More variable were the responses of glutathione peroxidases while superoxide dismutase remained almost constant. The interaction between lysosomal alterations and antioxidant defences is discussed and the results interpreted in view of the extreme environmental conditions for the Antarctic organisms. The results obtained from the transplantation experiment indicated only very limited effects on scallops translocated near the effluents of the Italian Base suggesting that the biological impact of the Base should not have major deleterious consequences on benthic marine communities.