PHOTOREACTIVATION OF ULTRAVIOLET LIGHT-INDUCED DAMAGE IN CULTURED FISH CELLS AS REVEALED BY INCREASED COLONY FORMING ABILITY AND DECREASED CONTENT OF PYRIMIDINE DIMERS |
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| Authors: | Akihiro Shima Mituo Kenaga Osamu Nikaido Hiraku Takebe Nobuo Egami |
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| Institution: | Department of Experimental Radiology, Shiga University of Medical Science, Otsu, Shiga 520-21, Japan;Department of Fundamental Radiology, Faculty of Medicine, Osaka University, Osaka 530, Japan;Radiation Biology Center, Kyoto University, Kyoto 606, Japan;Zoological Institute, Faculty of Science, University of Tokyo, Tokyo 113, Japan |
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| Abstract: | Abstract— Cultured cells derived from a goldfish were irradiated with 254nm ultraviolet light. Cell survival and splitting of pyrimidine dimers after photoreactivation treatment with white fluorescent lamps were examined by colony forming ability and by a direct dimer assay, respectively. When UV-irradiated (5 J/m2) cells were illuminated by photoreactivating light, cell survival was enhanced up to a factor of 9 (40min) followed by a decline after prolonged exposures. Exposure of UV-irradiated (15 J/m2) cells to radiation from white fluorescent lamps reduced the amounts of thymine-containing dimers in a photoreactivating fluence dependent manner, up to about 60% reduction at 120 min exposure. Keeping UV-irradiated cells in the dark for up to 120min did not affect either cell survival or the amount of pyrimidine dimers in DNA, indicating that there were not detectable levels of a dark-repair system in the cells under our conditions. Correlation between photoreactivation of colony forming ability and photoreactivation of the pyrimidine dimers was demonstrated, at least at relatively low fluences of photoreactivating light. |
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