THE ROLE OF METALLOTHIONEIN IN CADMIUM ACCUMULATION OF ARCTIC CHAR (SALVELINUS-ALPINUS) FROM HIGH ALPINE LAKES

Cadmium, copper and zinc concentrations were measured in water and org ans (gill, liver and kidney) of Arctic char (Salvelinus alpinus) from four alpine lakes in Tyrol, Austria. In comparison with control fish, concentrations of metals, especially of cadmium, were elevated in tiss ues of fish from low-alkalinity lakes. In contrast, low metal levels w ere detected in water of the alpine lakes, suggesting that the high ne t accumulation of metals in fish tissues might have been caused by inc reased availability of these metals under conditions of low alkalinity . After chromatographic purification and Reversed-Phase HPLC of tissue supernatants from lake fish, several metallothionein (MT) peaks were identified in liver and kidney. In both organs MT accounted for the se questration of virtually all the cadmium present in the tissues, and o f considerable proportions of copper and zinc. However, there were con spicuous organ-specific differences in the metal patterns of the isola ted MTs. Whereas liver MT of lake fish was dominated by copper and zin c despite high amounts of cadmium in the tissue, kidney MT showed a re versed pattern with cadmium predominating at the expense of copper and zinc. At slightly elevated cadmium concentrations in the liver, seque stration of this metal was achieved by displacement of zinc from MT bi nding sites, whereas at higher concentrations more MT was synthesized to bind excess amounts of the metal. The concentration of (Cd,Zn)-MT i n the liver was inversely correlated with lake alkalinity. Finally, si gnificant positive correlations were observed between the age of Arcti c char and hepatic concentrations of cadmium and (Cd,Zn)-MT.