BIOCHEMICAL-CHARACTERIZATION OF THE ANTIOXIDANT SYSTEM IN THE SCALLOPADAMUSSIUM-COLBECKI, A SENTINEL ORGANISM FOR MONITORING THE ANTARCTICENVIRONMENT

The scallop Adamussium colbecki can be profitably used for monitoring Antarctic coastal environments but its utility would be increased if c hemical analyses of pollutants were integrated with data on their biol ogical effects. Since oxidative stress is a common pathway of toxicity induced by xenobiotics, a preliminary biochemical characterization wa s carried out on the antioxidant system of this species and baseline d ata collected for future assessment of the anthropogenic impact in thi s remote area. The digestive gland and gills were investigated for lev els of glutathione and the activity of several glutathione-dependent a nd antioxidant enzymes: gluthathione reductase, EC 1.6.4.2; glyoxalase I, EC 4.4.1.5; glyoxalase II, EC 3.1.2.6; gluthathione S-transferases , EC 2.5.1.18; Se-dependent, EC 1.11.1.9 and Se-independent, EC 2.5.1. 18 glutathione peroxidases; catalase, EC 1.11.1.6; and superoxide dism utase, EC 1.15.1.1. The same enzymatic activities were measured for co mparison in the Mediterranean molluscs Mytilus galloprovincialis and P ecten jacobaeus. Very high levels of glutathione S-transferases were f ound in the digestive gland of both species of scallop compared to mus sels, suggesting the importance of different feeding behaviour among t hese molluscs. However, catalase activity, much higher in Adamussium c olbecki than in the Mediterranean molluscs, may represent a biochemica l adaptation to the Antarctic marine environment with high levels of d issolved oxygen. Enzymes from the Antarctic species appeared to be gen erally more active at low temperatures but, with a few exceptions, the ir activities increased at higher temperatures.