The behavioral genetics of Caenorhabditis elegans

Caenorhabditis elegans, a small free-living soil nematode, is an ideal organism for the genetic dissection of simple behaviors. Over 150 genes required for normal behavior have been identified. We review here the neural and genetic pathways underlying four of the best-studied C. elegans behaviors: locomotion, response to gentle touch, egg-laying, and chemotaxis. Mutations affecting these behaviors have identified genes which specify neuronal cell lineage, neuronal cell fate, and the formation of cell matrix cues involved in axonal guidance. Molecular analysis of genes required for normal behavior offers the prospect of characterizing functionally important nervous system proteins, regardless of their abundance or biochemical role.