title: Testing the unique amplification event and the worldwide migration hypothesis of insecticide resistance genes with sequence data.
abstract: In the mosquito Culex pipiens, over-production of esterases is a common insecticide resistance mechanism. Different alleles at the esterase A and B loci are known to occur in natural populations, as shown by enzyme electrophoresis and RFLP studies on the esterase B locus. Here we analyse the variability of the esterase A locus at the nucleotide level in mosquitoes possessing or lacking over-produced esterase A. A surprisingly high level of nucleotide polymorphism is found in coding and noncoding regions, and the extent of polymorphism detected is higher than that previously described for the most polymorphic loci in Drosophila. We also show that eight strains from different localities (Africa, America, Asia) that possess the over-produced esterase A2 share the same nucleotide sequence at the esterase A locus, strongly supporting the evolutionary scenario of a unique event of amplification of this gene followed by dispersal through migration rather than the occurrence of multiple independent mutational events of the gene.
authors.affiliation: Laboratoire Génétique et Environnement (C.C. 065), URA CNRS 327, Université de Montpellier II, France.
authors.forename: T
authors.initials: T
authors.lastname: Guillemaud
authors.forename: S
authors.initials: S
authors.lastname: Rooker
authors.forename: N
authors.initials: N
authors.lastname: Pasteur
authors.forename: M
authors.initials: M
authors.lastname: Raymond
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002265:Carboxylic Ester Hydrolases / Q000235:genetics; D003465:Culex / Q000201:enzymology / Q000235:genetics*; D004247:DNA / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D005784:Gene Amplification; D017344:Genes, Insect; D014644:Genetic Variation; D005828:Genetics, Population; D007305:Insecticide Resistance / Q000235:genetics*; D007438:Introns; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D011110:Polymorphism, Genetic
chemical_list: D017931:DNA Primers; D004247:DNA; C019724:arginine esterase; D002265:Carboxylic Ester Hydrolases