Heavy metal detoxication in the mussel Mytilus edulis-composition of Cd-containing kidney granules (tertiary lysosomes).

A new method for isolation and purification of lipofuschin granules (tertiary lysosomes) from mussel kidney is described. The results confirm previous ultrastructural evidence for the accumulation of Cd in these organelles. Granules from Cd-exposed animals contain higher concentrations of protein, Ca, Cd and S than those from control animals. Gel filtration experiments indicate that secondary lysosomes contain metallothionein whilst only low molecular weight Cd-complexes can be solubilised from tertiary lysosomes. Amino acid analysis of Cd-containing tertiary lysosomes show that they are not enriched in cysteine, indicating the absence of insoluble polymerised metallothionein.