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Published on: July 10, 2018
The association between malathion resistance and acetylcholinesterase in Drosophila melanogaster
Abstract:
The relationship between the 50% survival time for flies feeding on a malathion-containing medium and the activity of acetylcholinesterase (AChE) was determined for 15 isofemale lines of Drosophila melanogaster. A significant correlation was found (r = 0.28, P less than 0.05), with more resistant lines tending to have a lower level of AChE activity. An association between AChE and malathion resistance was also observed in a selection experiment. The AChE activity decreased in two of two populations selected for malathion resistance. AChE from these populations was altered in kinetic parameters (measured in crude head extracts) and electrophoretic mobility. Although the "resistant" AChE had a lower activity (Vm) on either a per milligram protein or a per individual basis, its apparent Km for acetylthiocholine was lower than that of "susceptible" AChE. Recombination mapping of both low activity and fast electrophoretic mobility localized these traits to the region of the structural locus (Ace) on the third chromosome. The AChE activity of flies heterozygous for a variety of Ace lesions (kindly provided by Dr. W. M. Gelbart) was consistent with this location. The changes in AChE were suggested to have been caused by selection of alleles at the Ace locus.
Insights
Flies resistant to malathion showed lower acetylcholinesterase (AChE) activity. This suggests that altered AChE, influenced by the Ace locus, is linked to insecticide resistance in Drosophila melanogaster.
Area of Science:
- * Genetics and Molecular Biology
- * Toxicology and Environmental Health
Background:
- * Insecticide resistance is a growing concern in pest management.
- * Acetylcholinesterase (AChE) is a key target for organophosphate insecticides like malathion.
- * Understanding the genetic basis of resistance is crucial for developing effective control strategies.
Purpose of the Study:
- * To investigate the relationship between malathion resistance and AChE activity in Drosophila melanogaster.
- * To identify the genetic locus associated with altered AChE in resistant flies.
Main Methods:
- * Assessed AChE activity and malathion survival time in 15 isofemale lines of D. melanogaster.
- * Conducted a selection experiment to observe changes in AChE activity under malathion pressure.
- * Analyzed kinetic parameters and electrophoretic mobility of AChE.
- * Used recombination mapping to localize genetic traits to the Ace locus on the third chromosome.
Main Results:
- * A significant negative correlation was found between malathion resistance and AChE activity (r = 0.28, P < 0.05).
- * Malathion-selected populations exhibited decreased AChE activity with altered kinetic parameters and electrophoretic mobility.
- * Low AChE activity and fast electrophoretic mobility were mapped to the Ace locus.
- * Heterozygous flies with Ace lesions showed consistent AChE activity patterns, supporting the locus's role.
Conclusions:
- * Selection for malathion resistance in D. melanogaster is associated with alterations in AChE.
- * The Ace locus on the third chromosome harbors alleles that confer malathion resistance through modified AChE.
- * These findings highlight the role of specific genetic variations in AChE in insecticide resistance mechanisms.
