Two acetylcholinesterase (AChE) genes cDNA fragments,Ag.acel and Ag.ace2,have been cloned from cotton aphid,Aphis gossypii Glover using degenerate primers with RT-PCR technique.Ag.acel gene cDNA fragment is of 282?bp encoding 94 amino acids,and Ag.ace2 gene cDNA fragment is of 264?bp encoding 88 amino acids.Both two putative AChE genes cDNA fragments share numerous similarities with those cloned from other insects.This is the first report of two AChE cDNA fragment sequences in the insect species,which provided the direct evidence of multiple AChE existence in insects.
Acetylcholinesterase (AChE) is the target of organophosphate and carbamate pesticides. Organophosphate resistance is worldspread in the cotton bollworm[Helicoverpa armigera (Hübner)]. With the degenerate primers we amplified a 281 bp cDNA fragment of acetylcholinesterase (AChE) gene in H. armigera by reverse transcription-polymerase chain reaction (RT-PCR) method using total RNA extracted from 4th larva as the template. The cDNA fragment was inserted into pGEMT vector and then cloned. The deduced amino acid sequence of AChE consisted of 94 residues. The sequence analysis indicated that the deduced amino acid sequence of the cDNA fragment shares high identity with AChE gene from other published insects and animals. The acquired sequence had 84%,79%,74%,70%,70%,72%,68%,61%,55% and 57% of amino acid residues identical to those of Leptinotarsa decemlineata(L.d.), Nephotettix cincticeps(N.c.),Anopheles stephensi(A.s.), Aedes aegypti(A.a.), Lucilia cuprina(L.c.), Drosophila melanogaster(D.m.), Musca domestica(M.d.), Meloidogyne incognita(M.i.), Torpedo californica(T.c.) and Gallus gallus(G.g.), respectively. All these results firmly established that the amplified cDNA fragment was the partial sequence of AChE gene in H. armigera. This is the first report of partial cDNA sequence of AChE in H. armigera.
