Comparative genomics of chemosensory protein genes (CSPs) in twenty-two mosquito species (Diptera: Culicidae): Identification, characterization, and evolution.

Ting Mei,Bo Li,Wen-Bo Fu,Bin Chen,Zheng-Bo He,J Joe Hull

doi:10.1371/journal.pone.0190412

Abstract

Chemosensory proteins (CSP) are soluble carrier proteins that may function in odorant reception in insects. CSPs have not been thoroughly studied at whole-genome level, despite the availability of insect genomes. Here, we identified/reidentified 283 CSP genes in the genomes of 22 mosquitoes. All 283 CSP genes possess a highly conserved OS-D domain. We comprehensively analyzed these CSP genes and determined their conserved domains, structure, genomic distribution, phylogeny, and evolutionary patterns. We found an average of seven CSP genes in each of 19 Anopheles genomes, 27 CSP genes in Cx. quinquefasciatus, 43 in Ae. aegypti, and 83 in Ae. albopictus. The Anopheles CSP genes had a simple genomic organization with a relatively consistent gene distribution, while most of the Culicinae CSP genes were distributed in clusters on the scaffolds. Our phylogenetic analysis clustered the CSPs into two major groups: CSP1-8 and CSE1-3. The CSP1-8 groups were all monophyletic with good bootstrap support. The CSE1-3 groups were an expansion of the CSP family of genes specific to the three Culicinae species. The Ka/Ks ratios indicated that the CSP genes had been subject to purifying selection with relatively slow evolution. Our results provide a comprehensive framework for the study of the CSP gene family in these 22 mosquito species, laying a foundation for future work on CSP function in the detection of chemical cues in the surrounding environment.

Highlights

Over time, insects have developed a complete chemosensing system to perceive chemical cues from external environment [1]
We identified a total of 130 putative Chemosensory proteins (CSP) genes from the genomes of these 19 Anopheles species, with an average of seven CSP genes per species (4 CSP genes in 1 species; 6 in 6 species; 7 in 6 species, and 8 in 6 species)
Among the 283 CSP genes identified across the 22 mosquito species, 269 genes are complete protein-coding sequences extracted from the genome assemblies

Summary

Introduction

Insects have developed a complete chemosensing system to perceive chemical cues from external environment [1]. Discerned olfactory stimuli are conveyed into the central nervous system via electrical signal transduction, producing a series of behavioral responses such as feeding, courtship, and avoidance to adapt to the external environment [1,2]. The lymph of the insect sensillum houses all processes and interactions by which the environmental odorant molecules reach the nerve membrane receptors [1]. Comparative genomics of CSPs in mosquitoes (2015FY210300), and the Science and Technology Research Project of Chongqing Municipal Education Commission (KJ1500328). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Methods

Results

Conclusion