Pilpel, Y; Lancet, D

Nature, vol. 398, no. 6725, pp. 285-287, 25 Mar 1999

Insects have exquisite chemosensory faculties--some can sense pheromones from several miles away. Yet although the genes for olfactory receptors in vertebrates and the nematode worm Caenorhabditis elegans have been known for years, their insect counterparts have remained elusive. Now, reports in Neuron and Cell describe the identification of genes for olfactory receptors in the fruitfly Drosophila melanogaster. These genes encode membrane receptor proteins that probably mediate odorant recognition in the fly. The discovery of Drosophila olfactory receptor genes was possible largely due to the availability, in databases, of genomic DNA sequences. To find these genes, Clyne et al. initially used a pure in silico approach. They assumed that Drosophila olfactory receptors would be structurally similar to the other known olfactory receptor genes. So, the authors identified two candidate genes from databases with an algorithm based on seeking their potential to code for proteins with multiple transmembrane segments. Vosshall et al. first identified an olfactory-specific rare messenger RNA (as befits a protein expected to be expressed in only a small subset of sensory neurons). Both groups then found further transmembrane homologues by searching the archives of the Drosophila genome project and they confirmed that, as expected, the dozen or so candidate genes are specifically expressed in sub-populations of cells within the fly olfactory organs--the antennae and maxillary palps.