The effects of exposure to heavy metal ions on cytochrome b sub(5) and components of the mixed-function oxidases from the digestive gland microsomes of the mollusc Monodonta turbinata

LT sub(50) values obtained for Monodonta turbinata exposed to heavy metal ions were as follows: 25.2 days after exposure to final concentration of 1.0 ppm Cd super(+2); 21.2 days for 0.1 ppm Hg super(+2); 25.2 for 0.5 ppm Cr super(+3) and 16.8 days for 0.5 ppm Cr super(+6), compared to 32.8 days for the control. The final concentrations of metal ions in the mollusc tissue increased by 20 times in the Hg super(+2), and by 10 times in the Cd super(+2) treated Monodonta , compared to the untreated control. The normal contents of cytochromes b sub(5) and P450 in M. turbinata) digestive gland microsomes were 195 plus or minus 51 and 58 plus or minus 20 nmol/mg protein, respectively. NADPH-cytochrome c reductase activity was 5.9 plus or minus 3.0 nmol/min/mg protein. Exposure to all heavy metal ions had a destructive effect on the two hemoproteins, especially on cytochrome P450, and a pronounced impact on NADPH-cytochrome c activity which was reduced to about 50% in the treated mollusc. No alarming concentrations of metal ions could be detected in M. turbinata collected from different sites along Israel Mediterranean coast.