Efficient measurement of H2O2 resistance in Drosophila using an activity monitor

We have established a method for the efficient measurement of oxidative stress resistance inDrosophila melanogaster, using a commercially available activity monitor. Conditions under which flies in glass tubes placed in the monitor can survive over one month at 25 °C were optimized. The active periods of flies were reduced by administration of H2O2 into the media in a dose-dependent manner. Although we used only eight flies per assay, far fewer individuals than in conventional methods, it was possible to detect the effects of H2O2 at a statistically significant level. Increased levels of H2O2 resistance were confirmed in transgenic flies overexpressing antioxidant enzymes, catalase or Cu/Zn superoxide dismutase. We applied the method to determine oxidative stress resistance in fly lines bearing insertions of a gene misexpression vector. H2O2 resistance in these flies varied considerably depending on the insertion, and positively correlated with previously determined longevity. We identified one insertion that conferred a significantly higher level of resistance to H2O2compared to controls. Molecular analysis of the insertion revealed that a misexpressed transcript matched an expressed sequence tag, and suggested that its full-length product was overproduced upon GAL4 activation. Our method should be applicable to the systematic screening for genes involved in the antioxidant mechanism in Drosophila.