Cadmium accumulation and metallothionein-like proteins in the Sea star Asterias rubens

Sea stars Asterias rubens, were exposed to cadmium (50 μg Cd 2+/litre) for 4 months. Accumulation rates were highest in body wall and pyloric caeca, while in the gonads a relatively low accumulation rate was measured. In all tissues Cd accumulation showed saturation kinetics. In the cytosolic fraction of pyloric caeca from Cd-exposed sea stars, Cd-binding proteins with a molecular weight of approximately 10 800 Da could be demonstrated. In cytosolic fractions of testes or ovaries, low molecular weight metal-binding proteins were absent and the accumulated Cd was bound exclusively to high molecular weight proteins.