Studies on the Labelling Patterns of Rna From Cerebral Cortex Nuclei

RNA labelling patterns in nuclei from rat cerebral cortex were investigated subsequent to intracerebral injection of [3H]uridine. Although there was a rapid uptake of label into the ‘heavy’ regions when nuclear RNA was analysed in density gradients, it was not possible to show conclusive evidence for 455 ribosomal precursor RNA. Methyl‐ation of 18S and 28S nuclear RNA became evident only after 2 hr and did not appear to involve the intermediacy of RNA species of higher molecular weight.