Epigenetics and the maintenance of gene activity states in Caenorhabditis elegans.

The nematode Caenorhabditis elegans has been the subject of many detailed investigations in developmental biology. Molecular analyses have failed to detect covalent alterations to DNA, such as methylation or rearrangement, during development of C. elegans. Genetic experiments indicate that imprinting of gamete genomes does not occur to any significant extent. The maintenance of gene activity states in this organism may depend predominantly on regulatory gene circuitry. Some possible examples of maintenance circuits are discussed.