Detection of DNA damage in individual cells from marine organisms using the single cell gel assay

The single cell gel (SCG) or comet assay is a simple method by which DNA damage is expressed as relative nuclear 'tail' length of gel-embedded cells following alkaline electrophoresis. While potentially applicable to any cell type, laboratory experiments were conducted to examine the utility of the SCG method for the detection of genotoxicity in cells of marine fish and invertebrates. Selected cells included those from flounder (Pleuronectes americanus) and oysters (Crassostrea virginica). In vitro exposures were used to optimize parameters and evaluate sensitivity, reproducibility and dose-responsiveness of the SCG method. In vivo exposures were used to examine the effects of factors such as intra-animal variability on low level DNA damage detection. In one experimental series, individually identified oysters were repeatedly sampled to monitor DNA damage and recovery following in vivo exposure to genotoxicant-spiked sediment. Preliminary results suggest that the SCG may be a useful tool to monitor for genotoxic environmental exposures and investigate pollution-mediated health effects.