title: Duplication, concerted evolution and purifying selection drive the evolution of mosquito vitellogenin genes.
abstract: BACKGROUND
  Mosquito vitellogenin (Vtg) genes belong to a small multiple gene family that encodes the major yolk protein precursors required for egg production. Multiple Vtg genes have been cloned and characterized from several mosquito species, but their origin and molecular evolution are poorly understood.
  
  
  RESULTS
  Here we used in silico and molecular cloning techniques to identify and characterize the evolution of the Vtg gene family from the genera Culex, Aedes/Ochlerotatus, and Anopheles. We identified the probable ancestral Vtg gene among different mosquito species by its conserved association with a novel gene approximately one kilobase upstream of the start codon. Phylogenetic analysis indicated that the Vtg gene family arose by duplication events, but that the pattern of duplication was different in each mosquito genera. Signatures of purifying selection were detected in Culex, Aedes and Anopheles. Gene conversion is a major driver of concerted evolution in Culex, while unequal crossover is likely the major driver of concerted evolution in Anopheles. In Aedes, smaller fragments have undergone gene conversion events.
  
  
  CONCLUSIONS
  The study shows concerted evolution and purifying selection shaped the evolution of mosquito Vtg genes following gene duplication. Additionally, similar evolutionary patterns were observed in the Vtg genes from other invertebrate and vertebrate organisms, suggesting that duplication, concerted evolution and purifying selection may be the major evolutionary forces driving Vtg gene evolution across highly divergent taxa.
authors.affiliation: The W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA.
authors.forename: Song
authors.initials: S
authors.lastname: Chen
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Armistead
authors.forename: Katie N
authors.initials: KN
authors.lastname: Provost-Javier
authors.forename: Joyce M
authors.initials: JM
authors.lastname: Sakamoto
authors.forename: Jason L
authors.initials: JL
authors.lastname: Rasgon
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D009033:Culicidae / Q000235:genetics*; D019143:Evolution, Molecular; D020440:Gene Duplication; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics*; D010802:Phylogeny; D012641:Selection, Genetic; D016415:Sequence Alignment; D014819:Vitellogenins / Q000737:chemistry / Q000235:genetics*
chemical_list: D019476:Insect Proteins; D014819:Vitellogenins
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