PHOTOREACTIVATION OF ICR 2A FROG CELLS EXPOSED TO SOLAR UV WAVELENGTHS

Abstract Exposure of ICR 2A frog cells to photoreactivating light (PRL) following irradiation with a fluorescent sun lamp (FSL) resulted in an enhancement in survival compared with FSL‐irradiated cells incubated in the dark. Hence, pyrimidine dimers played a role in the killing of cells exposed to the UV produced by this source. However, when the light was passed through a series of filters to remove increasing segments of the wavelength region shorter than 320 nm, the effect of the PRL progressively decreased, demonstrating that non‐dimer photoproducts play an increasingly important role in the killing of cells exposed to wavelengths approaching 320 nm. Cells were also exposed to 313 nm UV produced by a monochromator and it was found, once again, that the effectiveness of the PRL treatment depended on the filter the beam was passed through. These results indicate that for both FSL‐produced UV and 313 nm UV emitted by a monochromator, that the critical photoproducts induced within the cell depend on the filter used in conjunction with the UV source.