Delayed cell death and bystander effects in the progeny of Chinook Salmon Embryo cells exposed to radiation and a range of aquatic pollutants

Purpose: To determine whether delayed and bystander effects can be seen in both a non malignant teleost fish cell line, (CHSE) and a malignant teleost fish cell line (EPC) when exposed to low doses of ionising radiation and genotoxic pollutants. Methods: Teleost fish cells were briefly exposed to radiation and chemical toxins at low doses. Clonogenic survival was measured in the exposed population and the distant progeny of exposed cells to assess early and delayed cell death. Clonogenic survival was also measured in cultures, which received medium from briefly exposed cells to determine bystander effects. Results: The dose response pattern for both early and delayed cell death was found to differ for different stressors. Different mechanisms of cell death appear to be involved in the early cytotoxic effect and the delayed effect. No delayed cell death occurred in a transformed fish cell line (EPC). Bystander effects occurred in CHSE cells and were similar in intensity to previously reported mammalian cell bystander effects. Conclusions: The results may have implications for radiation and environmental protection of biota. They demonstrate that damage caused by low doses of radiation and common aquatic pollutants is not only similar but occurs in both acute and delayed forms.