The Genome of the Nematode Caenorhabditis elegans

The C. elegans genome project is part of a larger effort to understand how the information encoded in its DN A specifies the biology of this small nematode worm (Brenner 1974; Wood et al. 1988). It was selected for study because it is a highly tractable experimental system. Its short generation time (3 1/2 days), large brood size (300), and its modes of reproduction (self-fertilizing hermaphrodite and cross-fertilizing males) have aided genetic analysis. More than 950 genes have already been identified through mutation (Edgley and Riddle 1990; J. Hodgkin and R. Durbin, pers. comm.). Its small size (∼1 mm), defined number of cells (959 somatic nuclei), and transparent body and eggshell have permitted the elucidation of the cell lineage (Sulston et al. 1983) and the reconstruction of the entire nervous system at the level of the synapse (White et al. 1986). The relatively small genome has facilitated molecular investigations, which...