Response of Cyprinus carpio to copper exposure: alterations in reduced glutathione, catalase and proteins electrophoretic patterns.

This study was conducted to characterize the alterations in reduced glutathione (GSH) level, catalase (CAT) activity and proteins electrophoretic patterns in response to sublethal copper (Cu) exposure in Cyprinus carpio and to determine whether these responses are related to Cu accumulation in gills, chosen as target tissue. Fish were exposed to 0.1 and 1.0 mg/l Cu for 10 and 20 days. There were increasing level of Cu in the gill with increasing concentrations of metal in the exposure medium, and with increasing duration of exposure. GSH level and CAT activity increased in fish exposed to 1.0 mg/l Cu for both exposure periods, while no change was detected at the lower Cu concentration. Electrophoretic patterns of gill proteins by sodium dodecyl sulphate gel electrophoresis (SDS-PAGE) consist of 25-, 26-, 30-, 44- and 48-kDA medium molecular weight proteins (MMP) for five bands and 64-, 72-, 90- and 101-kDA high molecular weight proteins (HMP) for four bands in both control and treatment groups. The levels of 25-, 26- and 30-kDA MMP and 72- and 90-kDA HMP increased in response to Cu exposure. The present study demonstrated that Cu caused stress in fish gills and an acclimation with induction of GSH, CAT, MMP and HMP, which were important in the protection against metal damage, was observed.