Autoradiographically detected impairment of RNA synthesis pattern in 8-16 cell bovine embryos after irradiation

Early preimplantation bovine embryos at 8- or 16-cell stage were analysed by [5-3H]uridine autoradiography for distribution of newly synthesized RNA after 60Co irradiation with a single dose of 1 Gy, 2 Gy or 4 Gy gamma rays, respectively. Embryos irradiated with a single dose of 1 Gy showed equally decreased synthesis of RNA in nucleoplasma as well as in nucleolus. In embryos irradiated with a single dose of 2 Gy or 4 Gy, RNA synthesis was decreased and localized mostly on the periphery of the nucleus; in both cases of irradiation, the nucleus center being without labelling. In most of embryos irradiated with a dose of 4 Gy, the nucleoli were not labelled, and an increasing occurrence appeared of various nucleus chromatin segregation forms, mainly as its marginalization.