HUGGINS, T.*; LETT, K.; CATAPANE, E.J.; CARROLL, M.A.; Medgar Evers College; Medgar Evers College; Medgar Evers College; Medgar Evers College: Effects of Heavy Metals on Mitochondrial Cytochrome c Oxidase of the American Oyster, Crassostrea virginica

The ongoing oyster rehabitation study our lab has been conducting has shown that Crassostrea virginica transplanted to Jamaica Bay (JB), NY readily accumulate copper and other heavy metals. Many of these metals are believed to have prooxidant effects when present in excess. Mitochondria are sensitive to increased oxidative stress caused by metal toxicity. Previously, our lab determined that copper had a deliterious effect on 0₂ utilization in C. virginica gill mitochondria. In this study we compared the in vitro effects of copper to three other metals, cadmium, mercury and lead on the activity of a component of the respiratory chain, cytochrome c oxidase (COX). The oxidation of reduced cytochrome c by COX, in the presense and absence of added metals was determined spectrophometrically in detergent treated mitochondrial samples prepared from oyster gill. We found a 85% drop in COX activity when as little as 12.5 µg of copper was present in the assay mixture. Similar amounts of cadmium, mercury and lead caused a 49%, 41% and 34% drop in activity, respectively. Higher concentrations resulted in greater decreases. The toxic effects of these heavy metals on oyster gill mitochondrial respiration could be of physiological significance to the growth and long-term health of oysters and other marine animals living in a heavy metal polluted environment. This work was supported by grants 1R25GM62003 of NIGMS, 0516041071 of NYSDOE and 66288-0035 of PSC-CUNY. We thank Frank M. Flower & Sons, Inc., Oyster Bay, NY for supplying oysters.