2 NEURONAL G-PROTEINS ARE INVOLVED IN CHEMOSENSATION OF THE CAENORHABDITIS-ELEGANS DAUER-INDUCING PHEROMONE

Caenorhabditis elegans uses chemosensation to determine its course of development. Young larvae can arrest as dauer larvae in response to in creasing population density, which they measure by a nematode-excreted pheromone, and decreasing food supply. Dauer larvae can resume develo pment in response to a decrease in pheromone and increase in food conc entration. We show here that two novel G protein alpha subunits (GPA-2 and GPA-3) show promoter activity in subsets of chemosensory neurons and are involved in the decision to form dauer larvae primarily throug h the response to dauer pheromone. Dominant activating mutations in th ese G proteins result in constitutive, pheromone-independent dauer for mation, whereas inactivation results in reduced sensitivity to pheromo ne, and, under certain conditions, an alteration in the response to fo od. Interactions between gpa-2, gpa-3 and other genes controlling daue r formation suggest that these G proteins may act in parallel to regul ate the neuronal decision making that precedes dauer formation.