Candidate pheromone receptors of the silkmoth Bombyx mori

Communication via specific chemical signals is vitally important for the reproductive behaviour of many species. The first identified sex-attractant pheromone was bombykol from the silkmoth Bombyx mori. This female-released signalling compound is perceived by the male moth with extreme sensitivity and specificity. Antennal sensory cells supposedly respond to individual bombykol molecules and can efficiently distinguish bombykol from highly related structural analogues like bombykal, a second female-released pheromone component. In the four decades since the discovery of bombykol, the Bombyx mori system has continued to serve as an invaluable model system for unraveling the intricacies of chemical communication. The molecular basis for this extraordinary specific recognition of an extraneous compound is still elusive but probably based on specific receptors of the pheromone-responsive cells. In this study, molecular and bioinformatic approaches were employed to search for candidate pheromone receptors of Bombyx mori. A few receptor types were identified that are related to Heliothis candidate pheromone receptors. They were found to be almost exclusively expressed in male antennae, and double in situ hybridization experiments disclosed a characteristic topographic expression pattern that was reminiscent of pheromone-responsive cells. Furthermore, the receptor-expressing cells were closely associated with cells expressing the pheromone-binding protein. Together, the data support the view that the identified receptor types of Bombyx mori are candidate receptors for pheromone components.