INFLUENCE OF COPPER ON THE CLAMPROTOTHACA STAMINEA:EFFECTS ON GILLS AND OCCURRENCE OF COPPER-BINDING PROTEINS

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Abstract
P. staminea were exposed to a range of Cu concentrations of control (= 0.35), 7, 18, 39 and 82 .mu.g/l for 30 days. Mortalities were monitored during the exposure. Cu concentrations of 39 and 82 .mu.g/l were apparently extremely stressful with survivals of only 14 and 3%, respectively, after 30 days. At 7 and 18 .mu.g/l, survival was slightly reduced when compared to controls. Analyses for tissue Cu concentrations showed that the gill was the primary organ for the concentration of Cu and exhibited a linear relationship between its Cu content and the exposure concentration. Effects of Cu on the gill were demonstrated by a disruption of Na and K regulation at 39 .mu.g/l and increases in acid phosphatase activity at lower exposure concentrations. The former was associated with high mortalities, while the latter was considered to be a sublethal cytotoxic response. Two low-molecular-weight, Cu-binding proteins could be distinguished by differences in their eluting properties. In gill and muscle, Cu was associated with a protein of approximately 14,000 daltons while Zn was associated with a protein of approximately 10,500 daltons. In viscera and kidney, Cu and Zn co-eluted on the smaller of the 2 proteins and, in addition, considerable amounts of Cd were detected on the kidney low MW protein. The estimated MW of the smaller protein and its ability to bind Cu, Zn and Cd are similar to properties described for metallothionein.