Control of developmental timing in animals.

The molecular mechanisms that time development are now being deciphered in various organisms, particularly in Caenorhabditis elegans. Key recent findings indicate that certain C. elegans timekeeping genes are conserved across phyla, and their developmental expression patterns indicate that a timing function might also be conserved. Small regulatory RNAs have crucial roles in the timing mechanism, and the cellular machinery required for production of these RNAs intersects with that used to process double-stranded RNAs during RNA interference.