Effect of the complex I inhibitor rotenone on mitochondrial ROS levels and in the fly transcriptome

Abstract

ABSTRACT Background: Reactive Oxygen Species (ROS) are intriguing molecules that, for decades, have been considered as undesirable molecules that damaging the living cell, but recently, it has become proven that ROS plays a vital role to regulate and maintain many biological and physiological processes. The main sites of ROS production are the complexes of the respiratory chain in the mitochondria, especially complexes CI and CIII. It has been reported that knowing where the ROS production sites, is essential to determine the effect on the mitochondrial physiology and cellular haemostasis. Aim: To study the effects on the mitochondrial ROS levels and determine the changes in the fly transcriptome after using rotenone (ROS) which is CI inhibitor. Methods: We measured the level of ROS in Female Drosophila melanogaster that was treated using three different Electron Transport Chain (ETC) inhibitors, rotenone, malonate and myxothiazol, using ImageJ to analyse images of the fly brain. Also, we analysed data of RNA sequence reads into expression and differential expression values using an online tool called Galaxy. Result: Significant increase in ROS level was observed in the fly brain as a result of inhibiting complex I by rotenone. Inhibiting CIII by myxothiazol increase the level of ROS but did not trigger Reverse Electron Transport (RET). Also, there were 33 genes in the dataset appeared to be statistically significant, of which four genes were found indirectly connected to mitochondrial functioning. Conclusion: Our data reveal that there was a significant increase in the level of ROS. Moreover, 33 genes are relatively low number of genes compare to the whole genome. Therefore, the effect of rotenone on the fly transcriptome might not be plausible or may interfere with another defensive mechanism.