Small-molecule pheromones that control dauer development in Caenorhabditis elegans.

Area of Science:

• * Nematology
• * Molecular Biology
• * Chemical Ecology

Background:

• * The nematode *Caenorhabditis elegans* enters a dauer larval stage for survival under adverse conditions like high population density or low food supply.
• * Population density is sensed via a secreted small-molecule signal, historically termed the dauer pheromone.
• * Previous research identified components of this signal, but their potency and physiological relevance were not fully established.

Purpose of the Study:

• * To identify the specific chemical components of the *C. elegans* dauer pheromone.
• * To determine the relative potency of identified dauer pheromone components in inducing the dauer larval stage.
• * To establish the physiological relevance of identified dauer pheromone components as signaling molecules.

Main Methods:

• * Chemical analysis to identify compounds secreted by *C. elegans*.
• * Bioassays to measure the ability of identified compounds to induce dauer formation.
• * Structural elucidation of the active signaling molecules.

Main Results:

• * The dauer pheromone is composed of several structurally related ascarosides, which are derivatives of the dideoxysugar ascarylose.
• * Two specific ascarosides, designated as compounds 1 and 2, were identified as the primary potent components.
• * Compounds 1 and 2 are approximately 100 times more potent in inducing dauer formation than previously identified component 3, confirming their physiological relevance.

Conclusions:

• * The key components of the *C. elegans* dauer pheromone have been identified as specific ascarosides (1 and 2).
• * These potent ascarosides are crucial for *C. elegans* to sense population density and initiate the dauer survival response.
• * The identification of these compounds provides a foundation for discovering the receptors and signaling pathways involved in dauer formation.