The dauer larva is a specialized third‐larval stage of Caenorhabditis elegans that is long‐lived and resistant to environmental insult. The dauer larva is formed in response to a high external concentration of a constitu‐tively secreted pheromone. Response to the dauer‐inducing pheromone of C. elegans is a promising genetic model for metazoan chemosensory transduction. More than 20 genes have been identified that are required for normal pheromone response. The functions of these genes include production of the pheromone, exposure of sensory neuron (...) endings to the environment, structural and functional integrity of those sensory endings, and the capacity of sensory neurons to make appropriate output. Genetic evidence suggests that two partially redundant sensory pathways act in concert to control dauer formation. At least two classes of chemosensory neurons, ADF and ASI, are implicated in the pheromone response. On the basis of on these findings, a speculative model for the pheromone response is proposed. In this model, the neurons ADF and ASI are pheromone sensors that repress dauer formation in the absence of pheromone and dere‐press dauer formation in response to pheromone. It is currently unclear whether or not the two genetically defined sensory pathways both act in ADF and ASI. (shrink)

Mutations in the daf-2 and age-1 genes cause constitutive dauer larva formation and double adult life span in C. elegans. Their effect on life span has excited considerable interest and their effect on dauer formation has facilitated rapid progress in their genetic and molecular analysis. Two recent papers12,13 report that daf-2 encodes a member of the insulin-receptor family and that age-1 encodes a PI3 kinase subunit, a second-messenger producing enzyme known to act downstream of the mammalian insulin receptor. These findings (...) provide the first mechanistic insight into the well-established link between metabolism and aging. BioEssays 20:113–115, 1998. © 1998 John Wiley & Sons, Inc. (shrink)