Effect of cadmium on lysosomal responses in an arcid blood clam Anadara granosa L.

Abstract

Lysosomes and metallothioneins playa significant role in detoxification of a galaxy of pollutants including heavy metals. Lysosomal enzymes in digestive glands of the blood clam Anadara granosa varied significantly on exposure to Cd" alone and in the presence of Zn++, Cu" and EDTA. Changes in arylsulphatase activity were directly related to Cd levels in tissues. Bioaccumulation exceeding 50~g Cd g-! dry tissues showed an inhibitory effect on free and total arylsulphatase activity between 7 and 70% in the digestive glands. The lysosomal bound (latent/particle bound) arylsulphatase activity on the contrary increased but not significantly. Interestingly CdCl2 increased particle bound enzyme activity, whereas CdS04 decreased it, although both these salts are reported to completely ionize on addition to sea water forming exclusively various cadmium chloride salts (Ca 99%). Neither cadmium as CdCl2 nor as CdS04 , in the presence of Zn and EDTA showed any significant change in the enzyme activity. So also Zn and EDTA alone failed to show any change. However, Cd significantly reduced (total and free) arylsulphatase activity (P