Dicing Up RNAs

Abstract
What do stRNAs and siRNAs have in common apart from their small size and their ability to regulate gene expression? The enzyme Dicer it seems, according to a Perspective by Ambros discussing new findings by Hutvà gner et al. and Knight and Bass. Dicer cleaves larger dsRNA precursors into stRNAs and siRNAs. stRNAs regulate gene expression during worm development by preventing the mRNAs they bind to from being translated. siRNAs inactivate gene expression by binding to and degrading target mRNAs.