Level and amino acid acceptor activity of mouse brain tRNA during neural development.

Abstract

Abstract— The level of tRNA in mouse brain tissue was measured at various stages of postnatal development. The amount of tRNA per unit of brain wet weight was little, if at all, altered during the first 22 days after birth and decreased by 26 and 32 per cent by 56 days and maturity, respectively. On a DNA or cellular basis, there was no maturation‐dependent decrease in tRNA content. The total amino acid acceptor activity of tRNA for seven different amino acids was measured during neural development. There were considerable differences in the tRNA acceptor activities of individual amino acids within an age group; however on a DNA basis, there was little difference between tRNA preparations obtained from newborn and adult mouse brain tissue. The in vivo levels of aminoacylated‐tRNA for the seven amino acids of interest, were measured in brain tissue of 1–, 9–, 34, 70–day‐old and adult (over 9 months old) mice. Alterations in tRNA level, total tRNA acceptor activity, for each amino acid, and the levels of in uivo aminoacylation of tRNA were shown to be independent of developmental alterations in brain amino acid pool sizes. The results are discussed with regard to the availability of cellular amino acids for translational events during early mammalian brain development.