INDUCTION OF CYCLOBUTANE PYRIMIDINE DIMER PHOTOLYASE IN CULTURED FISHCELLS BY FLUORESCENT LIGHT AND OXYGEN STRESS

The expression of a gene for photolyase in RBCF-1 cells, a line of cul tured goldfish cells, is known to be enhanced by fluorescent light. We have now found that H2O2 is another strong inducer of cyclobutane pyr imidine dimer photolyase. Northern blot analysis suggested that regula tion by H2O2 occurs at the transcriptional level and the time course o f induction of photolyase by H2O2 was similar to that by fluorescent l ight. Treatment with fluorescent light in the presence of riboflavin, which is known as an endogenous photosensitizer, also enhanced the ind uction of photolyase. These results suggest the involvement of oxygen stress in the induction of photolyase by fluorescent light. A cell clo ne with high-level expression of the goldfish gene for photolyase was obtained by transfection with plasmids that expressed the goldfish pho tolyase in OL32 cells derived from another fish, the medaka (Oryzias l atipes). The induction of the medaka gene for photolyase was not affec ted by the high-level expression of the goldfish gene for this enzyme.