[Dynamics and dose-dependent changes in RNA and DNA synthesis in the thymus of irradiated animals].

Effects of an exposure of male vistar rats to 60Co--quanta in the doses of 0.2; 0.5; 1.0; 3.0; 5.0 Gy for 120 days; 7.0 Gy for 20 days and 9.0 Gy for 15 days on the dynamics of the thymic nucleinic acids have been studied. Experiments were conducted in 0.5, 1, 2, 4, 6, 8, 10, 15, 20, 30, 45, 65, 90, 120 days after an exposure to radiation. Essential shifts in metabolism of the nucleinic acids determined on the base of changes in their contents and ratio RNA/DNA have been established. The mass reduction of a radiosensitive organ was mainly due to a decrease in its cellular tissue. The greatest rate of RNA and DNA changes has been found to be on the first day following radiation. Significant reduce in the thymic total DNA synthesis can testify to a sharp decrease in the cellular production by this organ, and the decrease in the RNA synthesis gives evidence for a delay of the differentiation of the thymic cells. Defining the ratio of DNA to RNA can serve a qualitative indicator of the additional generations of the proliferating cells and finally of the size and state of trunk cells.