The School of Molecular and Cellular Biology at the University of Illinois at Urbana-Champaign

Insect olfaction and taste are major aspects of insect chemical ecology. With the identification of the insect chemoreceptor superfamily as a novel class of seven-transmembrane G-protein-coupled receptors, it is now possible to undertake detailed studies of the molecular basis of insect olfaction. We are studying the chemoreceptors revealed by the Drosophila fruit fly, Anopheles mosquito, and Apis bee genome sequences, as well as some we have identified in the Manduca moth genome. Expression patterns and molecular evolutionary analysis allow identification of candidates for particular roles in insect biology, such as mate recognition or animal/plant host detection. Detailed studies of particular receptors and their ligand specificity are being carried out in the Drosophila model system.

Comparisons of insect genomes reveal remarkable lineage-specific evolution. One aspect is the loss of genes in particular species, for example we find that about 500 “animal” genes have been lost from the Drosophila genome. They are still present in mosquito, moth, bee, and beetle genomes and have orthologs in mammalian genomes. These genes can therefore only be studied in these other insects. In addition, the expected completion of several additional insect genomes this decade opens the opportunity to study the tempo and mode of gene loss across the 300-million-year timescale of higher insect evolution.

We have long had a major program studying the molecular evolution of DNA transposons in insect and other animal genomes, and this continues with work on genes derived from DNA transposons in mammalian genomes. We are also undertaking molecular evolutionary analyses of the remarkably large families of candidate chemoreceptors that constitute 5% of the Caenorhabditis nematode genomes.