The homeotic gene lin-39 and the evolution of nematode epidermal cell fates.

The fate of ventral epidermal cells differs among nematode species. Nonvulval cells fuse with the epidermis in Caenorhabditis elegans, whereas the homologous cells undergo apoptosis in Pristionchus pacificus. The homeotic gene lin-39 is involved in the regulation of these epidermal cell fates. In Caenorhabditis, lin-39 prevents cell fusion of potential vulval cells and specifies the vulva equivalence group. Pristionchus vulvaless mutants that displayed apoptosis of the vulval precursor cells were isolated, and point mutations in lin-39 were identified. Thus, the evolution of these epidermal cell fates is driven by different intrinsic properties of homologous cells.