MULTIPLE EFFECTS OF FLUORESCENT LIGHT ON REPAIR OF ULTRAVIOLET-INDUCED DNA LESIONS IN CULTURED GOLDFISH CELLS

It is known that fluorescent light illumination prior to UV irradiatio n (FL preillumination) of cultured fish cells increases photorepair (P R) ability. In the present study, it was found that FL preillumination also enhanced UV resistance of logarithmically growing cells in the d ark. This enhancement of UV resistance differs from induction of PR be cause it was not suppressed by cycloheximide (CH) and it occurred imme diately after FL preillumination. The effects of FL preillumination on repair of UV-induced DNA lesions in the dark were examined by an endo nuclease-sensitive site assay to measure the repair of cyclobutyl pyri midine dimers, and by enzyme-linked immunosorbent assay to quantitate the repair of (6-4) photoproducts. It was found that excision repair a bility for (6-4) photoproducts in the genome overall was increased by FL preillumination. Moreover, a decrease in (6-4) photoproducts by FL illumination immediately after UV irradiation of the cells was found, the decrement being enhanced by FL preillumination with or without CH.