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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 1298

Aoyama Isao and Athanassios Kungolos; [Toxicity and bioaccumulation study for the effect of various chemical forms of mercury on Saccharomyces cerevisiae]. J.Japan Society on Water Environment 15(10):690-697, 1992

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It has been commonly known that mercury is one of the most toxic metals and that organic mercury is more toxic than inorganic mercury. This paper treats relationship between bioaccumulation and toxicity of various chemical forms of mercury on cell growth of the yeast Saccharomyces cerevisiae, DNA damage by mercury and effect of chelate agents on mercury toxicity. Four kinds of strains of S. cerevisiae were used. They are a wild type (AOY1) and three mutants. CA11-mutation repair-deficient mutant (rad18), CA13-exicion repair-deficient mutant (rad2) and CA15-recombination repair-deficient mutant (rad52) for DNA damage test. In terms of EC50 toward AOY1, the order of toxicity was Hg(NO3)2 > HgSO4 > HgCl2. For the same nitrate mercury, monovalent mercury (HgNO3) was more toxic than divalent mercury (Hg(NO3)2). Toxicity of organic mercury (CH3HgCl) on cell growth was two order higher than inorganic mercury (HgCl2). Comparing with the survival rate after 8 hours of inoculation and the content of both chemical forms of mercury in cells, the survival rate for CH3HgCl was about one hundredth of HgCl2, but the concentration of CH3HgCl in cells was about 170 times higher than that of HgCl2. Addition of chelate agents, EDTA and methl penicillamine to the medium did not modify the toxicity by mercury. The mutant which is deficient in recombination repair system was most sensitive for mercury among three mutants mentioned above.