| Popis: |
Glutathione-dependent degradation of parathion was studied in six strains of houseflies to find out whether it might be important as a cause of resistance. When supernatant fractions of high-speed centrifuged homogenates were fortified with glutathione and incubated with parathion, water-soluble products were formed. The rate of parathion detoxication was highest in a malathion-resistant strain (c. 4 μg parathion degraded per abdomen per hour), lowest in a susceptible strain, and intermediate in some other organophosphate-resistant strains. In one of the latter strains, E 1 , the gene for glutathione-dependent degradation is located on the second chromosome, closely linked with gene cm + . This is the same chromosome on which gene a for low ali-esterase activity and hydrolytic detoxication of paraoxon is located. It is not likely that the gene for glutathione-dependent degradation is identical with gene a , since it is also present in strain Nie which lacks gene a , and, therefore, the presence of a separate gene which is called gene g is postulated. Since the malathion-resistant strain was only 4-fold resistant to parathion, the glutathione-dependent degradation seems to confer only little resistance, at least to this insecticide. In three of the strains the products were identified. Three labeled products were formed from ethyl-labeled parathion: ethylglutathione, diethylphos-phorothionic acid, and desethylparathion. |
