Effect of elevated temperatures on the radiation sensitivity of yeast cells of different species

Abstract

The influence of hyperthermia on the survival of irradiated yeast cells of different species has been studied. The experiments reported in the paper have shown: (1) simultaneous action of ionizing radiation and high temperatures appeared to increase the radiation response by a factor of approximately 2.7 for diploid and only by a factor of 1.5 for haploid cells of wild-type; (2) the combined action of high temperature and ionizing radiation had no synergistic effect for rad51 mutant diploid yeast cells; (3) heating before or after irradiation did not alter the radiation response of yeast cells; (4) enhancement of yeast cell sensitivity by simultaneous action of hyperthermia and 239Pu-alpha-particles was negligible; (5) the magnitude and the rate of liquid holding recovery is lowered with increasing of irradiation temperature. On this basis, it was concluded that possible mechanism for thermal sensitization of yeast cells may involve the reduced capacity of cells to recover damages resulted from the combined action of both modalities.

Cellular radiation effects and hyperthermia cell cycle kinetics of radiation sensitive mutants of Saccharomyces cerevisiae after X-irradiation and hyperthermia

“…The synergism factor which is the ratio of the product of the surviving fraction of the combined treatment [19] is about two for an X-irradiation with 120 Gy in air. This result is at variance with reports on the same yeast strain by Petin and Berdnikova [20] who found no sensitization of the fadS1 mutant against v-irradiation by HT. A possible reason for this might be different irradiation conditions used by these authors.…”

Combined action of ultrasound and ionizing radiation on yeast cells

“…However, here again (y-rays + US)-treatment was more effective at the initial part of the survival curves. It has previously been found [13] that the combined action of elevated temperatures and ionizing radiation had more pronounced effect on diploid yeast cells than on haploid ones. Therefore, it may be worthwhile to fulfil similar investigation for combined action of ultrasound and F-rays.…”

“…This was found to be only about 10°C for the maximum intensity and exposure time used in these experiments. Since the cells can easily tolerate temperatures of 30-40° C [13], a temperature rise of 10 ° C seems unlikely to be significant. The ultrasonic dose rate was calculated by noting the initial rate of increase of the sample temperatures (without cooling) and computing the rate of energy deposition.…”

“…Our previous studies have shown that heat, in the form of elevated temperatures, interacts with ionizing radiation in a synergistic manner for yeast cells, the simplest model of eukaryotic cells; some new aspects of the interaction of these modalities have been observed using different yeast strains [13]. In particular, it was established that thermal potentiation of yeast cell responses to ionizing radiation may be connected both with a greater proportion of irreversible damage and a reduced rate of recovery.…”

The peculiarities of the interaction of radiation and hyperthermia in Saccharomyces cerevisiae irradiated with various dose rates

“…Linear regression calculation based on the multi-target single-hit mathematical model was used to fit the survival curves. Other details were as described previously (Petin and Berdnikova, 1979). Figure 1 provides an example of the basic experimental data observed in this investigation.…”