(Below N is a link to NCBI taxonomic web page and E link to ESTHER at designed phylum.) > cellular organisms: NE > Eukaryota: NE > Opisthokonta: NE > Metazoa: NE > Eumetazoa: NE > Bilateria: NE > Protostomia: NE > Ecdysozoa: NE > Panarthropoda: NE > Arthropoda: NE > Mandibulata: NE > Pancrustacea: NE > Hexapoda: NE > Insecta: NE > Dicondylia: NE > Pterygota: NE > Neoptera: NE > Holometabola: NE > Diptera: NE > Nematocera: NE > Culicomorpha: NE > Culicoidea: NE > Culicidae: NE > Culicinae: NE > Culicini: NE > Culex [genus]: NE > Culex [subgenus]: NE > Culex pipiens complex: NE > Culex quinquefasciatus: NE
LegendThis sequence has been compared to family alignement (MSA) red => minority aminoacid blue => majority aminoacid color intensity => conservation rate title => sequence position(MSA position)aminoacid rate Catalytic site Catalytic site in the MSA MEIRGLITRLLGPCHLRHLILCSLGLYSILVQSVHCRHHDIGSSVAHQLG SKYSQSSSLSSSSQSSSSLAEEATLNKDSDAFFTPYIGHGDSVRIVDAEL GTLEREHIHSTTTRRRGLTRRESSSDATDSDPLVITTDKGKIRGTTLEAP SGKKVDAWMGIPYAQPPLGPLRFRHPRPAERWTDRGHVFGDFPGATMWNR NTPLSEDCLYINVFVPRPRPKNAAVMLWIFGGGFYSGTATLDVYDHRTLA SEENVIVVSLQYRVASLGFLFLGTPEAPGNAGLFDQNLALRWVRDNIHRF GGDPSRVTLFGESAGAVSVSLHLLSALSRDLFQRAILQSGSPTAPWALVS REEATLRALRLAEAVNCPHDATKLSDAVECLRTKDPNELVDNEWGTLGIC EFPFVPVVDGAFLDETPQRSLASGRFKKTDILTGSNTEEGYYFIIYYLTE LLRKEEGVTVTREEFLQAVRELNPYVNGAARQAIVFEYTDWIEPDNPNSN RDALDKMVGDYHFTCNVNEFAQRYAEEGNNVFMYLYTHRSKGNPWPRWTG VMHGDEINYVFGEPLNSALGYQDDEKDFSRKIMRYWSNFAKTGNPNPSTP SVDLPEWPKHTAHGRHYLELGLNTTFVGRGPRLRQCAFWKKYLPQLVAAT SNLQVTPAPSVPCESSSTSYRSTLLLIVTLLLVTRFKI
Gene duplications occur at a high rate. Although most appear detrimental, some homogeneous duplications (identical gene copies) can be selected for beneficial increase in produced proteins. Heterogeneous duplications, which combine divergent alleles of a single locus, are seldom studied due to the paucity of empirical data. We investigated their role in an ongoing adaptive process at the ace-1 locus in Culex pipiens mosquitoes. We assessed the worldwide diversity of the ace-1 alleles (single-copy, susceptible S and insecticide-resistant R, and duplicated D that pair one S and one R copy), analysed their phylogeography and measured their fitness to understand their early dynamics using population genetics models. It provides a coherent and comprehensive evolutionary scenario. We show that D alleles are present in most resistant populations and display a higher diversity than R alleles (27 vs. 4). Most appear to result from independent unequal crossing-overs between local single-copy alleles, suggesting a recurrent process. Most duplicated alleles have a limited geographic distribution, probably resulting from their homozygous sublethality (HS phenotype). In addition, heterozygotes carrying different HS D alleles showed complementation, indicating different recessive lethal mutations. Due to mosaic insecticide control practices, balancing selection (overdominance) plays a key role in the early dynamics of heterogeneous duplicated alleles; it also favours a high local polymorphism of HS D alleles in natural populations (overdominance reinforced by complementation). Overall, our study shows that the evolutionary fate of heterogeneous duplications (and their long-term role) depends on finely balanced selective pressures due to the environment and to their genomic structure.
Gene duplication is thought to be the main potential source of material for the evolution of new gene functions. Several models have been proposed for the evolution of new functions through duplication, most based on ancient events (Myr). We provide molecular evidence for the occurrence of several (at least 3) independent duplications of the ace-1 locus in the mosquito Culex pipiens, selected in response to insecticide pressure that probably occurred very recently (<40 years ago). This locus encodes the main target of several insecticides, the acetylcholinesterase. The duplications described consist of 2 alleles of ace-1, 1 susceptible and 1 resistant to insecticide, located on the same chromosome. These events were detected in different parts of the world and probably resulted from distinct mechanisms. We propose that duplications were selected because they reduce the fitness cost associated with the resistant ace-1 allele through the generation of persistent, advantageous heterozygosis. The rate of duplication of ace-1 in C. pipiens is probably underestimated, but seems to be rather high.
One view of adaptation is that it proceeds by the slow and steady accumulation of beneficial mutations with small effects. It is difficult to test this model, since in most cases the genetic basis of adaptation can only be studied a posteriori with traits that have evolved for a long period of time through an unknown sequence of steps. In this paper, we show how ace-1, a gene involved in resistance to organophosphorous insecticide in the mosquito Culex pipiens, has evolved during 40 years of an insecticide control program. Initially, a major resistance allele with strong deleterious side effects spread through the population. Later, a duplication combining a susceptible and a resistance ace-1 allele began to spread but did not replace the original resistance allele, as it is sublethal when homozygous. Last, a second duplication, (also sublethal when homozygous) began to spread because heterozygotes for the two duplications do not exhibit deleterious pleiotropic effects. Double overdominance now maintains these four alleles across treated and nontreated areas. Thus, ace-1 evolution does not proceed via the steady accumulation of beneficial mutations. Instead, resistance evolution has been an erratic combination of mutation, positive selection, and the rearrangement of existing variation leading to complex genetic architecture.
Culex quinquefasciatus (Southern house mosquito) C. pipiens, C. pipiens pipiens (Northern house mosquito) (C. pungens) CqestBeta1 CqestB1 Esterase B1, esterase b2 esterase b8 esterase b10 esterase b11