[Structure of DNA from the rat thymus during prolonged exposure to tritium oxide and external gamma-irradiation].

Thymus depopulation, DNA destruction as estimated according to the level of single-stranded breaks (SSB) and DNA structural derangement revealed by the viscosimetric assay of alkaline lysed thymocytes were observed in the course of a prolonged (1 mos) radiation exposure to tritium oxide (the 1st group) and equidimensional external gamma-irradiation (the 2nd group) in a summary dose of 10 Gy in rats. Depletion and destruction were 1.5-2 times more pronounced in case of HTO exposure. A study of the repair has revealed an increase in the number of hardly repairable or irrepairable breaks by the end of the study: by the 25th day the number of SSB repaired after additional test irradiation was O and 30% in the rats of the 1st and 2nd groups respectively.