Biochemical characterization of the antioxidant system in the scallop Adamussium colbecki, a sentinel organism for monitoring the Antarctic environment

Abstract

 The scallop Adamussium colbecki can be profitably used for monitoring Antarctic coastal environments but its utility would be increased if chemical analyses of pollutants were integrated with data on their biological effects. Since oxidative stress is a common pathway of toxicity induced by xenobiotics, a preliminary biochemical characterization was carried out on the antioxidant system of this species and baseline data collected for future assessment of the anthropogenic impact in this remote area. The digestive gland and gills were investigated for levels of glutathione and the activity of several glutathione-dependent and 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 gluta-thione peroxidases; catalase, EC 1.11.1.6; and super-oxide dismutase, EC 1.15.1.1. The same enzymatic activities were measured for comparison in the Mediterranean molluscs Mytilus galloprovincialis and Pecten jacobaeus. Very high levels of glutathione S-transferases were found in the digestive gland of both species of scallop compared to mussels, suggesting the importance of different feeding behaviour among these molluscs. However, catalase activity, much higher in Adamussium colbecki than in the Mediterranean molluscs, may represent a biochemical adaptation to the Antarctic marine environment with high levels of dissolved oxygen. Enzymes from the Antarctic species appeared to be generally more active at low temperatures but, with a few exceptions, their activities increased at higher temperatures.