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 repair of cyclobutane pyrimidine dimers (CPD) and (6-4) photoproducts ([6-4] PD) in cultured goldfish cells (RBCF-1) at the exponentially growing phase. In this study, it is shown that even under the confluent condition of RBCF-1 cells, FL preillumination increased the disappearance of (6-4) PD in the dark. In addition, both at confluence and at the exponentially growing phase, the disappearance of (6-4) PD after PR treatment was increased by FL preillumination to RBCF-1 cells. Moreover, it was found that H2O2 pretreatment, followed by UV irradiation, of the exponentially growing cells also enhanced the disappearance of (6-4) PD in the dark and by photorepair treatment. The degree of enhancement by H2O2 pretreatment was almost the same as that by FL preillumination.