Submitted to: DNA Sequence
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/9/2006
Publication Date: 4/3/2007
Citation: Temeyer, K.B., Chen, A.C. 2007. Identification and characterization of a cDNA encoding the acetylcholinesterase of Haematobia irritans (L.) (Diptera: Muscidae). DNA Sequence. 18(2):85-91. Interpretive Summary: The horn fly, a biting fly which feeds on the blood of cattle has developed resistance to the organophosphate pesticides frequently used in fly control, compromising the ability to kill these pests. Organophosphate pesticides kill insects by inhibiting the activity of acetylcholinesterase, an enzyme essential to the function of the insect brain. Often insects become resistant to organophosphate pesticides as a result of natural selection for a mutant form of acetylcholinesterase that is not inhibited by the pesticide. A new study has determined the genetic sequence and structural composition of horn fly acetylcholinesterase. This information will enable researchers to rapidly sequence the acetylcholinesterase genes of horn flies resistant to pesticides to determine if they contain mutations in the acetylcholinesterase gene. If mutations are found, their effects on pesticide resistance can be determined, and sensitive, rapid tests can be developed to aid in choosing effective insecticides.
Technical Abstract: A 2217-nucleotide cDNA presumptively encoding acetylcholinesterase (AChE) of the horn fly, Haematobia irritans (L.) was sequenced. The open reading frame encoded a 91 amino acid secretion signal peptide and a 613 amino acid mature protein with 95% identity and 98% similarity to the AChE of Musca domestica (L.). Structural features characteristic of the M. domestica and Drosophila melanogaster AChEs are conserved in the H. irritans AChE. The M. domestica and D. melanogaster AChEs are target sites for organophosphate inhibition as previously shown (Walsh et al. 2001. Biochem. J. 359: 175-181, Kozaki et al. 2002. Appl. Entomol. Zool. 37: 213-218), strongly suggesting that this H. irritans AChE is the target site for organophosphate.