A divergent gene family encoding candidate olfactory receptors of the moth Heliothis virescens

The antennae of moths have been an invaluable model for studying the principles of odour perception. In spite of the enormous progress in understanding olfaction on the molecular level, for the moth one of the key elements in olfactory signalling, the odourant receptors, are still elusive. We have assessed a genome database of a heliothine moth (Heliothis virescens, Noctuidae) and employed exon-specific probes to screen an antennal cDNA library of this species. Analysis of isolated cDNA-clones led to the discovery of a divergent gene family encoding putative seven-transmembrane domain proteins. The notion that they may encode candidate olfactory receptors of the moth, was supported by a tissue-specific expression; several of the subtypes were exclusively expressed in antennae. By means of double-labelling in situ hybridization studies it was demonstrated that the receptors are indeed expressed in antennal sensory neurons; moreover, each receptor subtype appears to be expressed in a distinct population of sensory cells. The results strongly suggest that the newly discovered gene family indeed encodes olfactory receptors of moth.