Age-related changes in function of transfer ribonucleic acid of rat livers.

Changes in transfer ribonucleic acids during aging could be caused by alterations in regulation or mutation and give rise to slower and less accurate protein synthesis. Rodent liver parenchymal cells, purified from disaggregated livers, do decrease in ability to incorporate labeled amino acids during aging. Moreover, old rodents have a rapidly degraded fraction of liver soluble RNA which is absent from middle-aged animals. In addition, tRNAs purified from old unfractionated liver cannot be acylated as well as from young. High speed supernatant tRNAs from old and young liver are quite similar in acylation capacity. Analysis indicates that a defective subfraction of tRNA may be bound to the ribosomal fraction of the liver cell. Some evidence indicates that base modification levels differ in young and old rodent liver. Shifts in the proportions of lysine and serine isoacceptors during aging are consistent with this idea. One isoacceptor change is an increase in tRNAlys4, which is correlated with cell division capacity in other systems.