Control of developmental timing in Caenorhabditis elegans

Studies of the nematode Caenorhabditis elegans have identified genetic and molecular mechanisms controlling temporal patterns of developmental events. Mutations in genes of the C. elegans heterochronic pathway cause altered t emporal patterns of larval development, in which cells at certain larval st ages execute cell division patterns or differentiation programs normally sp ecific for other stages. The products of the heterochronic genes include tr anscriptional and translational regulators and two different cases of novel small translational regulatory RNAs. Other genes of the pathway encode evo lutionarily conserved proteins, including a homolog of the Drosophila Perio d circadian timing regulator, and a member of the nuclear receptor family o f proteins. These regulators interact with each other to elaborate stage-sp ecific regulatory switches and act through downstream effecters to control the timing of cell-type-specific developmental events.