Participation of Drosophila melanogaster alcohol dehydrogenase (ADH) in the detoxification of 1-pentene-3-ol and 1-pentene-3-one.

The participation of the ADH enzymes in the detoxification by D. melanogaster of 1-pentene-3-ol (also called pentenol) and its oxidized product, 1-pentene-3-one (usually known as ethyl-vinyl-ketone or pentenone) have been studied using the LR lines. For this purpose flies of AdhS AdhS (SS) and AdhF AdhF (FF) genotypes were independently pretreated with a 2 per cent isopropanol (2-propanol) solution and the survivors exposed to water, to a 0.0075 per cent pentenol solution or to a 0.00375 per cent pentenone solution. After one day in these solutions, the ability to tolerate both compounds was checked and the ADH activity of the surviving flies was measured and compared with those of control flies not pretreated with isopropanol. Additionally, the effects of pentenone on ADH enzymes have been studied by comparing them with those of acetone. Our results show that, in contrast to acetone, pentenone neither reduced significantly the ADH activity in vivo nor altered the normal proportion of ADH isozymes of either SS or FF flies. Our findings also demonstrate that the isopropanol pretreatment implied a considerable decrease in sensitivity not only to pentenol (60 and 91 per cent for SS and FF flies, respectively) but also to pentenone (72 and 80 per cent for SS and FF flies, respectively). After isopropanol pretreatment, FF flies continued exhibiting higher ADH activities than SS ones. However, FF pretreated flies displayed higher tolerance to pentenol and a similar tolerance to pentenone than SS animals. Our results suggest that pentenol (unsaturated secondary alcohol) and isopropanol (saturated secondary alcohol) may be detoxified by slightly different processes (both ADH-activity-dependent), and that pentenone could not be accumulated in the fly but transformed into another compound(s) by means of some ADH-independent mechanism(s).