No abstract

Cadmium and Zinc content was determined in organs of the Japanese scallop Mizuhopecten yessoensis, collected in 1984 from the Sea of Japan and aged between 1 and 8 yr. Under conditions of background Cd, Cd concentration in hepatopancreas and kidney increased linearly with age from 39 to 400#gg -1 dry wt in hepatopancreas, and from 100 to 640/~g g-1 dry wt in kidney. Such a pattern was not determined for Zn. Cd concentration in muscle, mantle and gill did not exceed 6/~g g -t dry wt in the oldest scallops. In subcellular fractions of the hepatopancreas, cytosolic Cd accounted for 71.7% in l-yr-old scallops and 98.8% in 8-yrolds. A similar ratio was established for gills, although gill Cd content was an order of magnitude lower. Analysis of Cd distribution in cytoplasmic proteins (of different molecular weight) in the hepatopancreas, showed that the amount of Cd bound to metallothionein-like proteins increases with scallop growth. A considerable amount of Cd also was detected in high molecular weight proteins. Thus, Cd accumulation, with age, in organs of the Japanese scallop is due to metal binding by cytoplasmic proteins.

No abstract

Cadmium-induced oxidative stress in the bivalve Modiolus modiolus is studied from the standpoint of the universality of the mechanism of free-radical oxidation. The kinetics of cadmium accumulation by the bivalve was revealed in a laboratory experiment. The gills accumulated higher Cd levels than the digestive gland. In the process of cadmium accumulation, there was an increase in lipid peroxidation products (malondialdehyde and lipofuscin) and a reduction in the total oxiradical scavenging capacity (TOSC). Cadmium induces oxidative stress in molluscan tissues through damage to the antioxidation system. Thus, TOSC can provide a useful biochemical indicator of early pathological changes in the cell or the organism, as well as of the environmental effects of heavy metal pollution.