Suppressors of Transforming Growth Factor-β Pathway Mutants in the Caenorhabditis elegans Dauer Formation Pathway

The dauer is a developmentally arrested alternative third larval stage of Caenorhabditis elegans. Entry into this state is regulated by environmental cues, including temperature, food, and the concentration of constitutively secreted dauer pheromone. Genetically, three parallel pathways have been found that regulate this process. Of these, the group 2 pathway, which includes the genes daf-1, daf-3, daf-4, daf-5, daf-7, daf-8, and daf-14, mediates the transduction of environmental signals through the ASI chemosensory neuron and encodes a TGF-β-related signaling pathway. To identify additional genes that function in this pathway, we carried out a screen for suppressors of mutations in daf-1, daf-8, and daf-14. From the total of 36 mutations, seven complementation groups were identified. Three complementation groups correspond to the previously described genes daf-3, daf-5, and daf-12. Three correspond to novel genes scd-1, scd-2, and scd-3. Genetic analysis of these scd genes is presented here. A fourth complementation group was represented by a single mutation sa315, which affects the daf-2/age-1 insulin-related signaling pathway.