An Extensive Class of Small RNAs in <i>Caenorhabditis elegans</i>

TLDR

Small noncoding RNAs such as lin‑4 and let‑7 act as temporal regulators in *C. elegans*, and the miRNA class is evolutionarily ancient, diverse, and widely conserved across bilaterians. The authors used bioinformatics and cDNA cloning to identify 15 novel miRNA genes in *C.

Abstract

The lin-4 and let-7 antisense RNAs are temporal regulators that control the timing of developmental events in Caenorhabditis elegans by inhibiting translation of target mRNAs. let-7 RNA is conserved among bilaterian animals, suggesting that this class of small RNAs [microRNAs (miRNAs)] is evolutionarily ancient. Using bioinformatics and cDNA cloning, we found 15 new miRNA genes in C. elegans. Several of these genes express small transcripts that vary in abundance during C. elegans larval development, and three of them have apparent homologs in mammals and/or insects. Small noncoding RNAs of the miRNA class appear to be numerous and diverse.