Mixed Function Oxidase Activity and Malathion Resistance in a Selected Strain of Drosophila Melanogaster

Abstract

The genetic factors controlling Mixed Function Oxidase (MFO) Activity and malathion resistance was studied in the larva and the adult of a malathion resistant strain of Drosophila melanogaster. In addition, the developmental expression and tissue localization of high MFO activity was characterized in the larva and the adult. Microsomal extracts from a strain with a resistant second chromosome were found to have increased amounts of protein with a relative molecular mass of 52 kD, while a strain with a resistant third chromosome was found to have increased amounts of proteins with relative molecular masses of 51 and 55 kD in the microsomal extract. MFO activity associated with a strain with a resistant second chromosome was found to be most concentrated in the intestine and abdominal wall of the imago, while found primarily in the malpigian tubules and the fat body of the larva. The mapping of genes on the second chromosome associated with larval resistance to malathion suggested two loci, a major resistance gene at 2-64 cM and a second minor resistance gene. The mapping of genes on the second chromosome associated with adult resistance again suggested two loci, one at 2-64 cM and a second just to the left of the marker black (48.5 cM). The mapping of genes on the second chromosome associated with high PNA demethylase activity (an MFO activity) in the adult suggested a locus at 2-64 cM and a second between 54.5 and 60.0 cM. The locus at 2-64 cM and a third locus between 48.5 and 51 cM was found to be associated with high 7-EC hydroxylase activity ( a second MFO activity) in the adult.