Abstract
Quantitative and qualitative changes in acetylcholinesterase confer resistance to insecticides. We have constructed several Drosophila melanogaster strains producing various amounts of enzyme by P-mediated transformation. Toxicological analysis of these strains demonstrates that resistance to organophosphorus insecticides is correlated with the amount of acetylcholinesterase in the central nervous system. Resistance may also be qualitatively determined. Comparison of the Drosophila acetylcholinesterase gene between a resistant strain caught in the wild and a wild type susceptible strain only revealed one nucleotide transition resulting in the replacement of a phenylalanine by a tyrosine. Flies mutant for acetylcholinesterase and rescued with a minigene mutagenized for this same transition produced an altered enzyme which renders flies resistant to pesticides.
Highlights
From the Centre de Recherche d’Antibes,Laboratoire de Biotogie des Invertkbres, F-06606, Antibes, France and the §Department of Zoology and Animal Biology, University of Geneva, 154 route de Malagmu, CH-1224 CEone-Boweries/ Geneva, Switzerland
We have constructed several Drosophila melanogasterstrains producing various amounts of enzyme by P-mediated transformation. Toxicological analysis of these strains demonstrates that resistance to organophosphorusinsecticides is correlated with the amount of acetylcholinesterase in the central nervous system
InAsceecttyiRlcctieohdsoeislitannedscteerase phenylalanine residue is conservedin other cholinesterases sequenced so far, suggesting that it is important for catalytic properties.Wehave verified that this base substitution is specific for the MH19 strain and did not originate from a cloning artifact by genomic Southern blot hybridization using as a probe an oligonucleotide bearing the mutation (Fig. 3R). To demonstrate that this changies responsible for the resistance, we introduced the MH19 mutatioinnthe minigene and rescued Ace- flies by P-element transformation.Rescued ki Cantoc ki resistant strain flies bearing the mutation arme ore resistant than theicrounterparts transformed with the wild type minigene (Fig. 4A)
Summary
From the Centre de Recherche d’Antibes,Laboratoire de Biotogie des Invertkbres, F-06606, Antibes, France and the §Department of Zoology and Animal Biology, University of Geneva, 154 route de Malagmu, CH-1224 CEone-Boweries/ Geneva, Switzerland. We have constructed several Drosophila melanogasterstrains producing various amounts of enzyme by P-mediated transformation Toxicological analysis of these strains demonstrates that resistance to organophosphorusinsecticides is correlated with the amount of acetylcholinesterase in the central nervous system. Using P element transformation of wild type flies or Acemutants, we have constructed several strains producing various amounts of acetylcholinesterase These transgenic strains enabled us to demonstrate thatthere is astrong correlation between the amount of acetylcholinesterase in the central nervous system and the susceptibility to insecticides. They display only20-25% of wild type activity (3.1 f 0.3, 3.5 f 0.45, and 2.9 f 0.3 units) probably because we used an intronless minigene insteadof the complete geneand only 1.5 k b of promoter sequences These flies are the most susceptible to insecticides (Fig. 1). These results demonstrate that resistance to organophosphorus compounds is correlated to the amount of acetylcholinesterasein the centralnervous
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