Accumulation, loss and molecular distribution of cadmium inMytilus edulis

Abstract

InMytilus edulis, accumulation and loss of Cd were analyzed under experimental conditions. Cd uptake by the whole soft body is linear, increasing significantly with increasing Cd concentrations in the uptake medium. Until 100 µg Cd l⁻¹, neither limitation of uptake nor any saturation process can be observed. Loss of Cd, measured after transfer of experimentally contaminated mussels to natural sea water, is exponential; biological half lives vary between 14 and 29 days. Gills are the primary sites of Cd uptake from the water, whereas in mid-gut gland, kidney, and mantle the uptake is retarded during the first few days. The mid-gut gland not only bears the main body load of Cd, but also shows the highest Cd concentrations. Gel chromatographic studies of mid-gut gland proteins reveal that Cd is eluated over the whole molecular weight range. Three metallothionein-like proteins with molecular weights of 6,600, 13,200, and 21,000 Dalton could be established. However, they cannot be taken as effective detoxification proteins, because more than 50% of the accumulated metal is bound to high molecular weight proteins.