Methylmercury (MeHg) is an environmental toxin capable of interacting with chromatin and suspected of inducing chromosomal damage. In order to further evaluate the cytogenetic effects of MeHg in vivo, Syrian hamsters received a single injection of either 5, 10, 15, or 20 mg/kg MeHg 24 hours presacrifice and preparation of bone marrow cells for cytogenetic analysis. Negative and positive controls (0.25 mg/kg Trenimon) were also incorporated into the experimental design. The most prevalant type of cytogenetic damage observed was chromosome pulverization. A dose-response increase in the incidence of chromosomal aberrations following MeHg treatment was not observed. However, both MeHg- and Trenimon-treated hamsters had significantly higher proportions of cells with pulverized chromosomes than did controls. The observation that fewer cells with pulverized chromosomes were detected in the 15 and 20 mg/kg MeHg groups as compared with the 5 and 10 mg/kg MeHg groups was attributed to cellular toxicity. These data indicate that MeHg severely damages hamster bone marrow chromosomes, as demonstrated by chromosome pulverization.
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