METALLOTHIONEIN-LIKE HEAVY-METAL BINDING-PROTEIN LEVELS IN ASIATIC CLAMS ARE DEPENDENT ON THE DURATION AND MODE OF EXPOSURE TO CADMIUM

The influence of duration and route of exposure to cadmium (Cd) on the levels of Cd and metallothionein (MT)-like heavy metal binding protein (HMBP) in soft tissues of the Asiatic clam Corbicula fluminea was asessed. Tissue concentrations of Cd and MT-like HMBP were highly correlated (correlation coefficient=0.97) during a continuous 30-day exposure of clams to dissolved Cd (0.10 mg l-1). Continuous exposure of Asiatic clams to dissolved Cd (0.10 mg lMIN1) for 30 days in a second study revealed that gills, mantle and adductor muscles (collectively referred to as GMA) had higher concentrations of Cd and MT-like HMBP than visceral mass of the same organism. Ingestion of Cd-contaminated algae by C. fluminea (4 h dayMIN1 for 15 days) resulted in higher concentrations of Cd and MT-like HMBP in visceral mass than GMA. These data indicate that the levels of Cd and MT-like HMBP in soft tissues of the Asiatic clam are dependent on the duration and mode of exposure to Cd.