The Gr Family of Candidate Gustatory and Olfactory Receptors in the Yellow-Fever Mosquito Aedes aegypti

The gustatory receptor (Gr) protein family contains most of the diversity in the insect chemoreceptor superfamily, including within it not only taste receptors but select olfactory receptors as well. Manual annotation of the Gr family in the genome sequence of the yellow-fever mosquito, Aedes aegypti, yielded a total of 114 potential proteins encoded by 79 genes. In the sequenced genome, 23 of these genes and protein isoforms are pseudogenic, leaving 91 putatively functional Grs. Comparison with our previously published set of 76 Grs encoded by 52 genes in the distantly related Anopheles gambiae mosquito revealed 13 new AgGrs encoded by 8 genes. Phylogenetic analysis reveals the conservation of carbon dioxide, sugar, and several orphan receptors in these 2 mosquitoes and Drosophila flies. On the other hand, most of these Grs are unique to mosquitoes and many are specific to the Aedes or Anopheles lineages, indicating their involvement in mosquito-specific aspects of both gustatory and olfactory perception. In particular, most instances of alternative splicing in orthologous loci appear to have evolved after the culicine–anopheline split ±150 million years ago.