| Abstract: | Possible dynamics of the incidence, repair, and realization of potential chromosome aberrations (PAs) was examined by indirect methods based on cytogenetic analysis of radiation effects. PAs were characterized as chemical modifications of DNA responsible for the incidence of structural aberrations of chromosomes. We interpreted our data as providing evidence that two types of radiation-induced PAs, differing in repair rates, could occur in the exposed cells: quick- (short-term) and slow (long-term) repairing PAs. We showed that the PA spectrum gradually changed with an increase in radiation dose within the interval from 24 to 150 cGy. This process was paralleled by changes in the cell response and chromosome resistance to radiation. Short-term PAs were induced mainly by low radiation doses ranging from 24 to 75 cGy. Their incidence was associated with activation of the corresponding repair process. Further increase in radiation dose resulted in changes in the PA spectrum, and doses of 150 cGy induced predominantly long-term PAs with concomitant activation of the appropriate repair process. Induction of repair occurred in the dose intervals limited by lower and upper threshold doses, Dl and Du. In our experiments, short-term PAs were repaired when Dl < 24 cGy and 126 cGy < Du < < 150 cGy. Long-term PAs were repaired when 75 cGy < Dl < 99 cGy and Du > 150 cGy. |
