title: Phylogenetic analyses of vector mosquito basic helix-loop-helix transcription factors.
abstract: Basic helix-loop-helix (bHLH) transcription factors play critical roles in the regulation of a wide range of developmental processes in higher organisms and have been identified in more than 20 organisms. Mosquitoes are important vectors of certain human diseases. In this study, Aedes aegypti, Anopheles gambiae str. PEST and Culex quinquefasciatus genomes were found to encode 55, 55 and 57 bHLH genes, respectively. Further phylogenetic analyses and OrthoDB and Kyoto encyclopedia of genes and genomes orthology database searches led us to define orthology for all the identified mosquito bHLHs successfully. This provides useful information with which to update annotations to 40 Ae. aegypti, 55 An. gambiae and 38 C. quinquefasciatus bHLH genes in VectorBase. The mosquito lineage has more bHLH genes in the Atonal, neurogenin (Ngn) and Hes-related with YRPW motif (Hey) families than do other insect species, suggesting that mosquitoes have evolved to be more sensitive to vibration, light and chemicals. Mosquito bHLH genes generally have higher evolutionary rates than other insect species. However, no pervasive positive selection occurred in the evolution of insect bHLH genes. Only episodic positive selection was found to affect evolution of bHLH genes in 11 families. Besides, coding regions of several Ae. aegypti bHLH motifs have unusually long introns in which multiple copies of transposable elements have been identified. These data provide a solid basis for further studies on structures and functions of bHLH proteins in the regulation of mosquito development and for prevention and control of mosquito-mediated human diseases.
authors.affiliation: Institute of Life Sciences, Jiangsu University, Zhenjiang, China.
authors.forename: D B
authors.initials: DB
authors.lastname: Zhang
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: A K
authors.initials: AK
authors.lastname: Liu
authors.forename: X H
authors.initials: XH
authors.lastname: Wang
authors.forename: C W
authors.initials: CW
authors.lastname: Dang
authors.forename: Q
authors.initials: Q
authors.lastname: Yao
authors.forename: K P
authors.initials: KP
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics*; D009033:Culicidae / Q000235:genetics*; D019143:Evolution, Molecular; D020224:Expressed Sequence Tags; D019476:Insect Proteins / Q000235:genetics*; D007303:Insect Vectors / Q000235:genetics*; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D016366:Open Reading Frames / Q000235:genetics; D010802:Phylogeny; D012641:Selection, Genetic; D017386:Sequence Homology, Amino Acid
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D019476:Insect Proteins
keywords: basic helix-loop-helix; phylogenetic analysis; transcription factor; vector mosquito