ARS | Publication request: The insect SNMP gene family

Submitted to: Journal of Insect Biochemistry and Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 25, 2009
Publication Date: July 1, 2009
Repository URL: http://hdl.handle.net/10113/31081
Citation: Vogt, R. G., Miller, N. E., Litvack, R., Fandino, R. A., Sparks, J., Staples, J., Friedman, R. and Dickens, J. C. 2009. The insect SNMP gene family. Insect Biochemistry and Molecular Biology. 39(7):448-456.

Interpretive Summary: Detection of odors and tastes in insects involves: 1) odorant binding proteins (OBPs) and odor degrading enzymes (ODEs) present in the haemolymph surrounding receptor cells, and 2) odorant receptors (Ors) present in the membranes of receptor cells. Sensory Neuron Membrane Protein (SNMP) also occurs in the membranes of receptor cells and is thought to function in pheromone reception in moths and fruit flies. Here we show that SNMPs occur in two forms and are distributed in four major insect orders comprising nearly 80% of all insect species. In fruit flies and the yellow fever mosquito, SNMPs may function in both smell and taste. The fact that SNMPs may function in pheromone detection makes them potential targets for chemicals aimed at disrupting behavior of insect pests, e.g. mosquitoes. These results provide entomologists and molecular biologists with important information for studies of the functional role of SNMPs in detection of volatile pheromones and non-volatile chemicals which may result in discovery of novel pest management strategies.

Technical Abstract: SNMPs are membrane proteins that have been shown to associate with chemosensory neurons in insects; in Drosophila melanogaster, SNMP1 has been shown to be essential for the detection of the pheromone cis vaccenyl acetate (Benton et al., 2001; Jin et al., 2008). To extend these observations to other insects we have characterized the SNMP gene family in 4 insect Orders that effectively covers the Holometabola, or some 80% of known insect species and the 300 million years of evolution since this lineage emerged: Lepidoptera (e.g. Bombyx mori, Antheraea polyphemus, Manduca sexta, Heliothis virescens, Helicoverpa, assulta, Helicoverpa armigera, Mamestra brassicae), Diptera (Drosophila melanogaster, D. pseudoobscura, Aedes aegypti, Anopheles gambiae), Hymenoptera (Apis mellifera) and Colepotera (Tribolium castaneum) (Nichols and Vogt, 2008). We have used cDNA sequences of SNMP1 and SNMP2 from various Lepidoptera species, D. melanogaster and Ae. aegypti, as well as BAC derived genomic sequences form Ae. aegypti as models for proposing corrected sequences of orthologues in the D. pseudoobscura, An. gambiae and B. mori genomes, as well as identifying orthologues in the C. pipiens quinquefasciatus genome. We then used these revised sequences to reanalyze the SNMP clade, suggesting that the SNMP1 and SNMP2 sub-clades are well supported throughout the dipteran and lepidopteran lineages, and plausibly throughout the Holometabola. We present evidence(dN/dS) that the Lepidoptera and Diptera genes are expressed and functional. We observed expansions of the SNMP1 sub-clade in C. pipiens quinquefasciatus. and T. castaneum which suggest that the SNMP1s may have an expanded functional role in these species. We finally observe that the SNMPs of D. melanogaster and Ae. aegypti are not exclusively expressed in antennae; if expression of these genes consistently associates with chemosensory organs, this suggests that the SNMPs may function in both olfactory and gustatory pathways.