Methylmercury (MeHg) is the most toxic form of Hg to wildlife, partly because of its ability to biomagnify through the food chain. Previous studies have shown that river otter (Lutra canadensis) is particularly susceptible to increased exposure and body burdens of MeHg due to the piscivorous nature of its diet. The objectives of this study were to attempt to establish a relationship between MeHg concentrations in otter tissues and DNA fragmentation using single cell electrophoresis (comet assay) as well as evaluate the effectiveness of the comet assay as a tool in genotoxicity assessment in field samples. Results of preliminary experiments indicate that both time and storage temperature markedly influence the rate of spontaneous DNA degradation. Increased numbers of freeze/thaw cycling also appear to have a negative effect on DNA integrity. In addition, a cell culture experiment was set up to measure the effects of differing levels of MeHg on a neuroblastoma cell line.

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