MOLECULAR BIOLOGY AND PHYSIOLOGY OF BITING FLIES AFFECTING LIVESTOCK
Location: Tick and Biting Fly Research
Title: Acetylcholinesterase of Stomoxys calcitrans (L.) (Diptera: Muscidae): cDNA sequence, baculovirus expression, and biochemical properties
Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 3, 2011
Publication Date: February 28, 2012
Citation: Temeyer, K.B., Chen, A.C. 2012. Acetylcholinesterase of Stomoxys calcitrans (L.) (Diptera: Muscidae): cDNA sequence, baculovirus expression, and biochemical properties. Veterinary Parasitology. 184(1):92-95.
Interpretive Summary: Stable flies are significant pests of both people and animals. Adult stable flies of both sexes must feed on fresh blood in order to reproduce, and they inflict a very painful bite. In addition, the flies are capable of passively transmitting disease organisms from infected animals as well as from feces or decaying material where they lay their eggs. Stable fly numbers have increased in recent years, apparently due to increased availability of larval habitat and also development of resistance to chemical pesticides. One of the major targets for chemical pesticides is an enzyme in the central nervous system of the fly that breaks down the neurotransmitter, acetylcholine. This enzyme, acetylcholinesterase, can become resistant to organophosphate or carbamate pesticides by mutation to a form that is insensitive to the presence of the pesticide. New research has identified the gene sequence that encodes information for making stable fly acetylcholinesterase, and has allowed production of a recombinant form of the natural enzyme allowing biochemical studies of its properties. This new information will allow identification of mutations that occur in nature that result in pesticide resistance, and will allow the development of rapid tests to identify resistance and guide the choice of pesticides used for control of stable fly populations. In addition, the recombinant enzyme may also allow the development of new control technologies based on the structure of the enzyme.
A 2193-nucleotide cDNA encoding acetylcholinesterase (AChE) of the stable fly, Stomoxys calcitrans (L.) was expressed in the baculovirus system. The open reading frame encoded a 91 amino acid secretion signal peptide and a 613 amino acid mature protein with 96% and 94% identity to the AChEs of Haematobia irritans (L.) and Musca domestica (L.), respectively. Structural features characteristic of the M. domestica, H. irritans, and Drosophila melanogaster AChEs are largely conserved in the S. calcitrans AChE. The M. domestica and D. melanogaster AChEs are target sites for organophosphate inhibition as previously shown, strongly suggesting that this S. calcitrans AChE is the target site for organophosphate.