The differentiation and function of the touch receptor neurons of Caenorhabditis elegans.

We have identified several genes required for four aspects of the differentiation and function of a set of six touch receptor neurons in the nematode Caenorhabditis elegans: (1) the generation of appropriate cells; (2) the specification of those cells to differentiate as touch receptors; (3) the maintenance of the differentiated state; and (4) the expression of products need for the cell function. Three major conclusions about the development of the touch cells arise from the analysis of these genes. First, specification of cell fate is a combinatorial process. At least seven genes, none of which are expressed solely in these cells, are needed to restrict the expression of touch-cell features in the appropriate cells. Second, the differentiated state must also be maintained. Three genes appear necessary for this maintenance function. Third, regulation of development is not strictly linear; at least one gene is needed at more than one stage of differentiation. In addition to being interested in the factor that determine cell fate, we are also interested in understanding the molecular basis of mechanosensory transduction. The function class genes are particularly important in this regard, especially those that when mutant result in the loss of the touch response without producing any obvious morphological defects in the touch cells.