To transmit his genome, the C. elegans male needs to mate with a hermaphrodite. To achieve reproductive success, the male has evolved a wide repertoire of sexual behaviors that rely heavily on sensory stimuli from the hermaphrodite. A blend of secreted short chain ascarosides promotes male aggregation at locations where hermaphrodites are present (Srinivasan, Kaplan et al., 2008). Although this pheromone assists in mate location, hermaphrodite secretions alone are neither sufficient nor necessary to retain males and to suppress male exploratory and mate seeking behavior. For this, contact with an adult hermaphrodite is required (Barrios et al., 2008). Here we present evidence that a pheromone different from that identified by Srinivasan, Kaplan et al. is present on the hermaphrodite cuticle and regulates contact-dependent male sexual behaviors. Using a combination of genetic and chemical manipulations we have perturbed the hermaphrodite cuticle and analyzed their effect on two contact-dependent male sexual behaviors: retention and response. We find that the hermaphrodite cuticle appears to be composed of sexualized chemicals. Males with a feminized hypodermis (by expression of
dpy-7::
tra-2 IC-construct provided by W. Mowrey and D. Portman) can retain other males andelicit a high level of response to contact, whereas wild type males cannot. Male response efficiency is significantly reduced against surface coat mutant hermaphrodites
srf-2, 3 and 5and against hermaphrodites resistant to bacterial adhesion to their cuticle
bus-2, 4, 8, 12and 17. These genes encode galactosyl-transferases and sugar transporters, suggesting that the hermaphrodite contact pheromone is a glyco-conjugate. In contrast,
daf-22 hermaphrodites, which are defective in the production of the ascaroside blend for aggregation, fully retain males and elicit a wild type male response. In order to chemically isolate the contact-based pheromone we have developed an assay to carry out activity-guided fractionation. We have been able to remove activity from wild type hermaphrodites with organic solvents. Applying this hermaphrodite extract to a bus mutant restores male response to wild type levels. Barrios,A., Nurrish, S. and Emmons, S. W.(2008). Sensory regulation of C. elegans male mate-searching behavior. CurrBiol 18, 1865-71. Srinivasan,J., Kaplan, F., Ajredini, R., Zachariah, C., Alborn, H. T., Teal, P. E., Malik,R. U., Edison, A. S., Sternberg, P. W. and Schroeder, F. C. (2008). A blend of small molecules regulates bothmating and development in Caenorhabditis elegans. Nature454, 1115-8.