REPAIR OF (6-4)-PHOTOPRODUCTS IN CULTURED GOLDFISH CELLS AT CONFLUENCE OR TREATED WITH H2O2

Previously we reported that fluorescent light (FL) illumination prior to UV irradiation (FL preillumination) had multiple effects on the rep air of cyclobutane pyrimidine dimers (CPD) and (6-4) photoproducts ([6 -4] PD) in cultured goldfish cells (RBCF-1) at the exponentially growi ng phase. In this study, it is shown that even under the confluent con dition of RBCF-1 cells, FL preillumination increased the disappearance of (6-4) PD in the dark. In addition, both at confluence and at the e xponentially growing phase, the disappearance of (6-4) PD after PR tre atment was increased by FL preillumination to RBCF-1 cells. Moreover, it was found that H2O2 pretreatment, followed by UV irradiation, of th e exponentially growing cells also enhanced the disappearance of (6-4) PD in the dark and by photorepair treatment. The degree of enhancemen t by H2O2 pretreatment was almost the same as that by FL preilluminati on.