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Co‐selection and replacement of resistance alleles to Lysinibacillus sphaericus in a Culex quinquefasciatus colony
Author(s) -
Melo Chalegre Karlos Diogo,
Tavares Daniella A.,
Romão Tatiany P.,
Menezes Heverly Suzany G.,
Nascimento Nathaly A.,
Oliveira Cláudia Maria F.,
deMeloNeto Osvaldo P.,
SilvaFilha Maria Hele. L.
Publication year - 2015
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.13364
Subject(s) - biology , allele , culex quinquefasciatus , genetics , gene , midgut , microbiology and biotechnology , phenotype , larva , ecology , aedes aegypti
The Cqm1 α‐glucosidase, expressed within the midgut of Culex quinquefasciatus mosquito larvae, is the receptor for the Binary toxin (Bin) from the entomopathogen Lysinibacillus sphaericus . Mutations of the Cqm1 α‐glucosidase gene cause high resistance levels to this bacterium in both field and laboratory populations, and a previously described allele, cqm1 REC , was found to be associated with a laboratory‐resistant colony (R2362). This study described the identification of a novel resistance allele, cqm1 REC ‐ 2 , that was co‐selected with cqm1 REC within the R2362 colony. The two alleles display distinct mutations but both generate premature stop codons that prevent the expression of midgut‐bound Cqm1 proteins. Using a PCR ‐based assay to monitor the frequency of each allele during long‐term maintenance of the resistant colony, cqm1 REC was found to predominate early on but later was replaced by cqm1 REC ‐ 2 as the most abundant resistance allele. Homozygous larvae for each allele were then generated that displayed similar high‐resistance phenotypes with equivalent low levels of transcript and lack of protein expression for both cqm1 REC and cqm1 REC ‐ 2 . In progeny from a cross of homozygous individuals for each allele at a 1 : 1 ratio, analyzed for ten subsequent generations, cqm1 REC showed a higher frequency than cqm1 REC ‐ 2 . The replacement of cqm1 REC by cqm1 REC ‐ 2 observed in the R2362 colony, kept for 210 generations, indicates changes in fitness related to traits that are unknown but linked to these two alleles, and constitutes a unique example of evolution of resistance within a controlled laboratory environment.