| Abstract: | Experiments have been carried out on Chlorella, beans, wheat and developing loach eggs to study the dose-response relationship (dose-function of dose rate) with 90Sr, 90Y and 147Pm as the sources of beta-radiation. The yield of point mutations in Chlorella under 147Pm and that of chromosome aberrations in cells of bean roof and apical meristem tissue as well as in meiosis of wheat and bean cells irradiated by 90Sr- 90Y is proved to show degree dependence at a dose less than 1. It means that the dose which doubles the number of induced mutations is not constant and depends on the dose rate. Reverse relationship is shown between dose intensity and genetic effect per dose unit. The decrease in the yield of genetic damages in the range of dose rates analysed is supposed to be due to repair activation induced by ionizing radiations. In view of these results, consideration is given to the role of the level of spontaneous mutagenesis in estimation of the resolution of test systems. An increase in the level of the spontaneous mutational process is shown to increase the size of population samples which are ment, when analysed, to reveal statistically significant differences between the effect observed and the level of spontaneous mutagenesis. The possibility of application of the experimental results to the prediction of effects of ionizing radiations on natural animal and plant populations is considered. |
