Total RNA, rRNA and poly(A)+RNA abundances during aging in Caenorhabditis elegans

This is the second in a series of studies in which we characterize gene expression at the level of RNA during aging in the nematode Caenorhabditis elegans. Here, we quantitatively analyzed total RNA, poly(A)+ RNA, and ribosomal RNA as a function of chronological age in two different strains (TJ1060 and TJ1061) having wild-type life spans and in a long-lived age-1 mutant strain (TJ1062). In addition, we compared the age-dependent abundance patterns of these RNAs in two different culture environments. Total RNA yield did not show a consistent pattern of age-related changes. However, total RNA yield was significantly higher in all three strains when grown on agar than when grown in liquid. In addition, total RNA yield was significantly lower from strain TJ1061 than from strain TJ1060 and TJ1062. Relative to total RNA, rRNA did not exhibit any consistent differences with age, strain or environment. Poly(A)+ RNA decreased by 23-43% in old animals from the long-lived strain and one of the wild-type strains, but was not changed in the second wild-type strain. In addition, control experiments to determine the amount of RNA contributed by E. coli bacteria (present in the nematode culture medium as a food source) suggest that the age-1 mutant strain has a lower bacterial infection rate, which may contribute to the increased life span of this strain.