Characterization of olfactory genes in the antennae of the Southern house mosquito, Culex quinquefasciatus.

Odorant reception in insects is mediated by different families of olfactory proteins. Here we focus on the characterization of odorant-binding proteins (OBPs), "plus-C" odorant-binding proteins ("plus-C" OBPs), chemosensory proteins (CSPs) and sensory neuron membrane proteins (SNMPs) families from the Southern house mosquito, Culex quinquefasciatus, a vector of pathogens implicated in multiple human diseases. Using bioinformatics and molecular approaches, we have identified a diversity of genes in the genome of Culex quinquefasciatus and examined their expression profiles by RT-PCR and real-time quantitative PCR. Based on their high transcript enrichment in female antennae compared to non-olfactory tissues, we have identified twelve OBPs, two "plus-C" OBPs and two SNMPs that likely play important roles in odorant reception. Transcripts of two genes were clearly enriched in female antennae compared to male antennae, whereas other genes displayed relatively equivalent transcript levels in antennae of both sexes. Additionally, eight genes were found to be transcribed at very high levels in female antennae compared to CquiOR7, suggesting they might encode highly abundant olfactory proteins. Comparative analysis across different mosquito species revealed that olfactory genes of Culex quinquefasciatus are related to putative orthologs in other species, indicating that they might perform similar functions. Understanding how mosquitoes are able to detect ecologically relevant odorant cues might help designing better control strategies. We have identified olfactory genes from different families which are likely important in Culex quinquefasciatus behaviors, thus paving the way towards a better understanding of the diversity of proteins involved in the reception of semiochemicals in this species.