Relationships between accumulation of a 60 kDa stress protein and scope-for-growth in Mytilus edulis exposed to a range of copper concentrations

Blue mussels, Mytilus edulis, were exposed in the laboratory for 7 days to a range of Cu concentrations (0 to 100 μg/liter) to test the feasibility of using the accumulation of a 60 kDa stress protein, also referred to as heat shock protein 60 (hsp60), as a molecular indicator of contaminant exposure and ecological status. At the end of the experiment, scope-for-growth (SFG) measurements were completed to assess whole organism physiological condition. In addition, antibodies raised against hsp60 were employed as probes for Western blot analysis and immunobinding assays of mantle tissue. Physiological measurements revealed a significant (p < 0·05) decrease in the SFG index for organisms at 32 and 100 μg/liter Cu. Western blot analysis indicated that the abundance of hsp60 was greater in tissues exposed to elevated Cu concentrations than in controls. Quantitation of hsp60 accumulation as determined by a dot immunobinding assay demonstrated a significant correlation between hsp60 accumulation and nominal Cu concentration in the seawater. Significant (p < 0·1) increases in accumulation of hsp60 over controls was detected at 3·2 μg/liter Cu and higher, Cu concentrations which were substantially lower than that at which a significant decrease in SFG was observed. These data suggest that hsp60 accumulation may hold promise as a molecular indicator of contaminant exposure and an early warning of adverse biological effects.