Synthesis of Cu-binding proteins in different tissues of mussels exposed to the metal

The results demonstrate that Cu²⁺, when present in sea water at the sublethal concentration of 0.08 ppm, is able to induce, within 48 h, the synthesis of Cu-binding proteins having a molecular weight similar to that of the metallothioneins (12 000), in the gills and in the mantle of the mussels. In the digestive gland of the animals, part of the copper present in the cells is always associated to soluble low molecular weight thionein-like proteins; the level of these copper-binding proteins increases greatly in the mussels exposed to Cu²⁺. In addition, it has also been shown that an extremely low concentration of copper (0.015 ppm)—similar to the Cu²⁺ concentration found in polluted coastal areas—is able to stimulate the synthesis of thionein-like Cu-binding proteins in the three tissues examined within 2–5 days.