THE NEUROMOLECULAR MECHANISMS THAT COORDINATE FOOD AVAILABILITY WITH C. elegans MALE SEXUAL BEHAVIOR A Dissertation by TODD

The Neuromolecular Mechanisms That Coordinate Food Availability with C. elegans Male Sexual Behavior. (August 2008) Todd R. Gruninger, B.S., Texas A&M University Chair of Advisory Committee: Dr. L. Rene Garcia Organisms must coordinate behavioral and physiological responses to changing environmental conditions. In the nematode C. elegans, the presence or absence of food in the environment affects many metabolic and behavioral responses, including fat homeostasis, lifespan, and male mating. Specifically, male mating behavior normally occurs when a well-nourished male encounters a hermaphrodite, and is repressed if the male is under-nourished. To understand how environmental changes influence the drive to carry out specific behavioral tasks, I used C. elegans male mating as a model. Previously, mutants were isolated that display male mating behavior at inappropriate times, i.e. in the absence of mating cues. Loss of function mutations in the ERG K channel, UNC-103, results in spontaneous seizures of the male sex muscles. Interestingly, I found that food deprivation can suppress unc-103(lf)-induced seizures, suggesting that pathways activated under this environmental condition can suppress the excitability of the mating circuit. Using molecular, genetic, and behavioral assays, I identified sensory and molecular mechanisms that reduce sex-muscle excitability under food-deprived