Oxidative DNA Damage Induced by 364-nm UVA Laser in Yeast Cells

The mechanisms of the toxic eŠects of UVA (320–400 nm) irradiation remain unclear. The actions of monochromatic longer wavelength UVA, in particular, have been di‹cult to analyze because of a lack of a powerful light source; however, a UVA laser that can be used for biological studies was recently developed. In the current studies, we examined the eŠects of 364-nm irradiation on yeast cells using a potent UVA laser. We found that, when irradiated under aerobic conditions, yeast cells lacking Ogg1 glycosylase were more sensitive than those with Ogg1. The ability of the 364-nm light to kill the yeast cells was almost eliminated by purging with argon gas. The mutagenic eŠects of the UVA irradiation did not appear to be enhanced by a lack of Ogg1. These results indicate the killing of yeast cells by 364-nm UVA may be dependent on oxidation and may involve DNA lesions that can be repaired by Ogg1.