TISSUE-SPECIFIC DIFFERENCES IN ACCUMULATION OF STRESS PROTEINS IN MYTILUS-EDULIS EXPOSED TO A RANGE OF COPPER CONCENTRATIONS

This study examines the expression and accumulation of two major stres s proteins, stress70 and chaperonin60 (cpn60), in the gill and mantle of blue mussels, Mytilus edulis, which were exposed to a range of Cu c oncentrations for 7 days. Scope-for-growth (SFG), mortality, and Cu ac cumulation in gill and mantle tissue were also measured to monitor the physiological effects of Cu exposure in the organisms. In general Cu accumulated to a greater extent in gill relative to mantle tissue. A r eduction of SFG index and increased mortality was also observed at the two highest Cu concentrations. We found no significant differences be tween the two tissues in the expression of cpn60 and stress70 for muss els exposed to Cu ranging from 0 to 10 mu g/liter Cu (cpn60) and 0 to 32 mu g/liter Cu (stress70) in seawater. However, differences in the s tress response were observed between the gill and the mantle tissue of mussels exposed to higher Cu concentrations. Chaperonin concentration s were greater than an order of magnitude higher in the gill than in t he mantle for these mussels. Further, although the accumulation of str ess70 was similar between the two tissues, two additional proteins rea cted with antibody to stress70 in gill, but not mantle tissue, of muss els exposed to 100 mu g/liter Cu. This study suggests that the physiol ogical processes involved in contaminant uptake, distribution, and det oxification may affect the tissue-level expression of the stress respo nse in multicellular organisms. Further, the intensity of the stress r esponse and relative concentrations of chaperonin and stress70 among t issues may help identify tissues which are the most vulnerable to dama ge caused by a particular environmental stressor. (C) 1994 Academic Pr ess, Inc.