Transfer RNA methylase activity in normal and dystrophic chicken muscle

Brain transfer RNA. I. Methylation of newly synthesized tRNA

Present study demonstrates differences between the labeling patterns of rat cerebral cortex and cerebellum. Although the initial rates of synthesis and methylation of tRNA from these two regions of brain are different, their final degree of methylation is the same in both the cases. Differences in the rates of incorporation of radioactivities in both the tissues can be explained by the differences in the rates of equilibrium of the labeled precursors with the pools. Increased incorporation of labeled uridine into cerebral cortical tRNA following dibutyryl cAMP treatment probably resulted from higher uptake of the labeled precursor due to permeability changes.

Brain transfer RNA. II. Analysis of modified nucleosides

Transfer RNAs were isolated from rat and calf brains and their nucleosides were analysed by tritium derivative technique. Qualitative changes in the minor nucleoside components were compared on the fluorograms which showed differences in the intensities of spots. Cerebellar and cortical tRNAs were also compared, but revealed no significant quantitative differences in their methylated constituants despite 60% higher methyltransferase activity observed in cerebellum compared to cerebral cortex. An overall similarity was noticed between the relative proportions of the major and minor nucleosides of tRNAs derived from rat or calf brain, expressed as mol%. Brain tRNA was also analysed by two-dimensional polyacrylamide gel electrophoresis which showed qualitative and quantitative changes during postnatal development.