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

## TL;DR

This study shows how introducing alternative mitochondrial enzymes in fruit flies affects their metabolism and oxidative stress levels.

## Contribution

The paper demonstrates the metabolic and redox impacts of expressing yeast NDI1 and ascidian AOX in Drosophila.

## Key findings

- NDI1-expressing flies showed increased food intake and oxidative stress markers.
- AOX-expressing flies had reduced lipid peroxides and altered glucose metabolism.
- NDI1 may increase energy demand, while AOX could reduce superoxide production.

## Abstract

The 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.

Female 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.