ACETYLCHOLINESTERASE CDNA OF THE CATTLE TICK, BOOPHILUS-MICROPLUS - CHARACTERIZATION AND ROLE IN ORGANOPHOSPHATE RESISTANCE

Acetylcholinesterase is the target of organophosphate and carbamate pe sticides. Organophosphate resistance is widespread in the cattle tick, Boophilus microplus, in Australia. We have isolated a cDNA of acetylc holinesterase from B. microplus and show that it would encode a protei n 62 kDa in size. The predicted amino acid sequence contains all the r esidues characteristic of an acetylcholinesterase. Alternative splicin g of the transcript was detected at both the 5' and 3' ends. Alternati ve splicing at the 5' end would result in two proteins differing by si x amino acids. This is the first report of alternative splicing of the N-terminal coding region in a cholinesterase. No point mutations were detected in the acetylcholinesterase gene from organophosphate resist ant strains of B. microplus. Alternative explanations for resistance t o organophosphates in B. microplus are discussed. (C) 1998 Elsevier Sc ience Ltd. All rights reserved.