[Biosynthesis and maturation of ribosomal RNA in thymocyte subpopulations of X-irradiated rats].

A study was made of RNA biosynthesis and maturation in the control and irradiated thymocyte fractions isolated in a ficoll-paque gradient. The post-irradiation impairment of rRNA processing was manifested by the enhancement of pre-rRNA biosynthesis and the increase in 18S rRNA "wastage" during the first hours following X-irradiation. The changes were most pronounced in the thymocyte fraction sedimenting in a gradient zone with the density of above 1.077.