Mitotic recombination and inactivation in Saccharomyces cerevisiae inducedby UV-radiation (254 nm) and hyperthermia depend on UV fluence rate

In experiments with wild-type diploid yeast cells of Saccharomyces cerevisi ae, the synergistic interaction of ultraviolet (UV) light (wavelength, 254 nm) and heat (45-60 degreesC) was studied both for mutagenic and inactivati on effects. Simultaneous hyperthermia and UV light treatments increase the frequency of UV-induced mitotic intergenic recombination (crossing-over) an d cell inactivation. The enhancing effect was a function of UV light fluenc e rate. It is concluded that the effect of hyperthermia on low fluence UV o r high fluence W irradiation results in comparable effects on survival and mitotic recombination suggesting similar modulation by hyperthermia of the effects induced by UV at different fluence rates. The interpretation of the data obtained was carried out within the widely accepted point of view con sidering the synergistic effects as a result of repair ability damage. (C) 2001 Elsevier Science B.V. All rights reserved.