Expression of yeast NADH dehydrogenase and ascidian alternative oxidase affects metabolism and free radical processes in Drosophila.

objectiveThe study aimed to investigate the effect of overexpression of alternative mitochondrial enzymes such as yeast NADH dehydrogenase I (NDI1) and alternative oxidase (AOX) on the metabolism, oxidative stress and feeding behavior of the fruit fly Drosophila melanogaster. Experimental flies with expression of NDI1 or AOX were generated using genetic crosses based on the GAL4-UAS system.

resultsFemale flies with NDI1 expression showed increased food consumption, markers of oxidative stress (elevated carbonyl protein content), and increased activity of the detoxification enzyme glutathione-S-transferase, along with decreased activity of key metabolic enzymes, including dehydrogenases of isocitrate, lactate, and glucose-6-phosphate. In contrast, AOX-expressing flies had reduced lactate dehydrogenase activity, decreased levels of lipid peroxides, and increased glutathione reductase activity. Lower free glucose levels with elevated glycogen stores were found in AOX-expressing female flies. The results suggest that the alternative electron transport chain may alter energy and redox metabolism. In particular, NDI1 expression could increase energy demand and induce compensatory hyperphagia. In contrast, AOX might bypass key steps of proton gradient generation, potentially reducing superoxide production.