Sensory experience and sensory activity regulate chemosensory receptor gene expression in Caenorhabditis elegans

Changes in the environment cause both short-term and long-term changes in a n animal's behavior. Here we show that specific sensory experiences cause c hanges in chemosensory receptor gene expression that may alter sensory perc eption in the nematode Caenorhabditis elegans. Three predicted chemosensory receptor genes expressed in the ASI chemosensory neurons, srd-1, str-2, an d str-3, are repressed by exposure to the dauer pheromone, a signal of crow ding. Repression occurs at pheromone concentrations below those that induce formation of the alternative dauer larva stage, suggesting that exposure t o pheromones can alter the chemosensory behaviors of non-dauer animals. In addition, ASI expression of srd-1, but not str-2 and str-3, is induced by s ensory activity of the ASI neurons. Expression of two receptor genes is reg ulated by developmental entry into the dauer larva stage. srd-1 expression in ASI neurons is repressed in dauer larvae. str-2 expression in dauer anim als is induced in the ASI neurons, but repressed in the AWC neurons. The AS I and AWC neurons remodel in the dauer stage, and these results suggest tha t their sensory specificity changes as well. We suggest that experience-dep endent changes in chemosensory receptor gene expression may modify olfactor y behaviors.