Biochemical and ultrastructural observations of long-term silver accumulation in the mussel, Mytilus edulis

The cellular distribution and chemical forms of Ag were determined in mussels after accumulation of the metal from sea water. The major accumulations were either in the vacuoles of connective tissue macrophages, where it was associated with S, or in deposits in the fibrillar layer of the basement membranes of the digestive diverticulum and kidney epithelia, where it was bound to the sulphydryl and sulphate groups of glycoproteins and proteoglycans. In acutely exposed animals, about 10 % of the accumulated Ag was found in a (Ag, Cu)-binding protein with characteristics indicating that it may be a metallothionein. There was a concomitant increase in the body Cu levels after Ag exposure and 40 % of this was bound to this low molecular weight metal-binding protein.