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(22-32) Detection of DNA strand breaks in fish cells exposed in vitro and in vivo to cadmium. Kilemade, M.*,1, O'Brien, N.2, O’Halloran, J.1, van Pelt, F.3, Sheehan, D.4, Mothersill, C.5, 1 University College Cork, Cork, Ireland2 University College Cork, Cork, Ireland3 University College Cork, Cork, Ireland4 University College Cork, Cork, Ireland5 Dublin Institute of Technology, Dublin, Ireland ABSTRACT- Cadmium poses a serious environmental threat to aquatic ecosystems however the mechanisms of its toxicity remain somewhat unclear. The single cell gel electrophoresis or comet assay was employed to determine whether or not cadmium induces DNA strand breaks in cells from a salmonid fish cell line (CHSE-214) and in primary cultured rainbow trout epidermal and spleen cells incubated in vitro for 6, 24 and 48 hrs with sub-cytotoxic concentrations (1-10 Key words: Comet Assay, Fish Cells, CdCl2 |
M) of cadmium chloride (CdCl2), a known aquatic pollutant and widely suspected genotoxicant. CdCl2 produced a statistically significant concentration-dependent increase in the percentage of DNA in the comet tail in both in vitro systems. Increases in tail length and tail moment were also observed. Following 6, 24 and 48 hrs direct exposure of rainbow trout to CdCl2 spiked water, epidermal, spleen and blood cells also demonstrated a significant increase in tail DNA, tail length and tail moment, indicative of increased DNA strand break formation. In the in vivo exposures comets were induced at levels of CdCl2 that were lower than those in the in vitro exposures. This study has demonstrated the potential of the comet assay to detect DNA strand breakage in fish cells exposed in vitro and in vivo to suspected aquatic genotoxicants. This approach may well provide a sensitive, non-specific end-point of genotoxicity as part of an environmental bio-monitoring program. The in vivo exposure data set validated that of the in vitro set. This has potential implications for the scaling down of numbers of whole animals needed for bio-monitoring purposes and for the classification of potentially genotoxic chemicals.