Biochemical analysis of allozyme copper and cadmium tolerance in fish using starch gel electrophoresis

Abstract

AbstractThe in vitro effects of copper and cadmium on fish enzyme activity were assayed by combining the metals with the biochemical stains used to resolve these enzyme systems on starch gels. The effects of copper and cadmium on the activity of PGM‐2, GPI‐2 and IDH‐2 enzymes in mosquitofish were assayed using stain‐metal mixtures containing 2.0 ml 0.1 m CuSO4 · 5H2O or 0.1 m CdSO4. Enzymes whose activities were effected by copper in this initial test were resolved using a series of stain‐metal mixtures containing copper at lower concentrations to determine effect threshold concentration ranges and to determine concentration ranges that might produce differential effects on activity among allozymes of a single protein. Interspecific differences in the effect of copper on the activity of PGM‐2 enzyme variants were examined for 17 fish species from seven locations.Copper was found to effect the activity of PGM‐2, GPI‐2, and IDH‐2 enzymes in mosquitofish and intraspecific and interspecific differences existed in the copper sensitivity of enzymes in a number of the fish species tested. Allozyme phenotypes at the PGM‐2 locus in mosquitofish observed on test gels (0.9 mg Cu/L) suggests that two isoalleles, one copper‐tolerant and one copper‐sensitive, are present at this locus.