Changes in the expression of genes involved in protein synthesis during Drosophila aging.

A characteristic feature of aging organisms is their loss in homeostatic functions, including the ability of protein synthesis and turnover. It has been proposed that in senescent Drosophila melanogaster the peptide synthesis elongation factor (EF) EF-1 alpha may become limiting and be responsible for the age-related decline in protein synthesis. We have determined the expression levels of EF genes in Drosophila and have compared them with the expression of several other genes involved in the protein synthesis pathway. Steady-state levels of mRNAs for EF-1 alpha F1 and F2, of mRNAs for four ribosomal proteins, of total poly A+ RNA, rRNA, and tRNA were measured. We show that most RNAs studied decrease immediately after eclosion. There is no evidence for EF-1 alpha mRNA becoming limiting in old flies. Our data suggest that down-regulation of RNA polymerase I-, II-, and III-mediated transcription may contribute to an age-related decrease in protein synthesis or other homeostatic functions.