Principal Investigator David Bartel
In addition to miRNAs and endogenous siRNAs, our high-throughput data has revealed previously unknown types of RNAs. Recently identified classes of small RNAs in animals include Piwi-interacting RNAs (piRNAs) and 21U-RNAs. The piRNAs (found in collaboration with Robert Kingston's lab and also by several other labs) are ~29-nt RNAs that are likely involved in mammalian sperm development. The 21U-RNAs are an intriguing class of small RNAs found in worms. Precisely 21 nt long, they begin with a uridine but are diverse in their remaining 20 nt. They originate from ~12,000 genomic loci dispersed in two broad regions of one chromosome -- primarily between protein-coding genes or within their introns. These loci share a large upstream motif that is conserved in other nematodes, presumably because of its importance for producing this class of small RNAs.