Toxic effects of copper on antioxidative and metabolic enzymes of the marine gastropod, onchidium struma

The goals of this study were to evaluate the acute and sublethal toxicity of copper (Cu²⁺) on the marine gastropod, Onchidium struma, and to examine the utility of enzymatic parameters as indicators of Cu²⁺ exposure. In a semistatic renewal test, the 96-hour median lethal concentration of Cu²⁺ for O. struma, 74.80 mg/L, was higher than that for other intertidal species. The activities of the antioxidative enzymes, Cu/Zn superoxide dismutase (Cu/Zn-SOD) and catalase (CAT), and those of the metabolic enzymes-acid phosphatase (ACP), alkaline phosphatase (AKP), glutamic-oxaloacetic transaminase (GOT), and glutamic-pyruvic transaminase (GPT) -in both hepatopancreas and muscle were determined after a 1-week exposure to Cu ²⁺ (range 1.35 to 4.20 mg/L). The activities of both Cu/Zn-SOD and CAT were higher in hepatopancreas than muscle. In addition, there was a negative correlation between Cu²⁺ concentration and Cu/Zn-SOD activity in hepatopancreas, whereas a positive correlation was observed for CAT activity. Concentration-dependent changes in ACP and AKP activity showed a similar trend in hepatopancreas, increasing then decreasing and, finally, a slight increase. In contrast, ACP activity was positively correlated with Cu²⁺ across the concentration range tested. In both hepatopancreas and muscle, both GOT and GPT were activated by lower concentrations of Cu²⁺ and inhibited at higher concentrations.