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Resistance‐associated point mutations of organophosphate insensitive acetylcholinesterase, in the olive fruit fly Bactrocera oleae
Author(s) -
Vontas J. G.,
Hejazi M. J.,
Hawkes N. J.,
Cosmidis N.,
Loukas M.,
Hemingway J.
Publication year - 2002
Publication title -
insect molecular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.955
H-Index - 93
eISSN - 1365-2583
pISSN - 0962-1075
DOI - 10.1046/j.1365-2583.2002.00343.x
Subject(s) - biology , organophosphate , bactrocera , acetylcholinesterase , complementary dna , point mutation , serine , tephritidae , glycine , open reading frame , pest analysis , bactrocera dorsalis , amino acid , microbiology and biotechnology , genetics , biochemistry , enzyme , mutation , botany , peptide sequence , gene , pesticide , ecology
Abstract A 2.2‐kb full length cDNA containing an ORF encoding a putative acetylcholinesterase (AChE) precursor of 673 amino acid residues was obtained by a combined degenerate PCR and RACE strategy from an organophosphate‐susceptible Bactrocera oleae strain. A comparison of cDNA sequences of individual insects from susceptible and resistant strains, coupled with an enzyme inhibition assay with omethoate, indicated a novel glycine‐serine substitution (G488S), at an amino acid residue which is highly conserved across species (G396 of Torpedo californica AChE), as a likely cause of AChE insensitivity. This mutation was also associated with a 35–40% reduction in AChE catalytic efficiency. The I199V substitution, which confers low levels of resistance in Drosophila , was also present in B. oleae (I214V) and in combination with G488S produced up to a 16‐fold decrease in insecticide sensitivity. This is the first agricultural pest where resistance has been associated with an alteration in AChE, which arises from point mutations located within the active site gorge of the enzyme.