TOXIC LEVELS OF SELENIUM IN ENZYMES AND SELENIUM UPTAKE IN TISSUES OFA MARINE FISH

Acute toxicity of selenium as selenite in Zosterisessor ophiocephalus by ip injection was studied. The 50% lethal dose and 50% lethal time w ere measured to be 0.29 ppm and 96 h, respectively. Se concentrations in liver, gill, skin and muscle, and Cyt. P450 level, Se-GPx, and Tota l GPx enzyme activities in liver were also assessed at different doses and times after injection. Starting at 0.3 ppm injected dose, enzyme activities and Se concentration in tissues, but not in muscle, showed significant differences from the control group. A threshold behavior w as inferred. Normal conditions of enzyme activities and Se concentrati on in tissues were restored about 1 wk after injection. Biological eli mination half-lives were about 2 d for liver and gill, and 5 d for ski n.