The effect of mitochondrial superoxide on drosophila lifespan

Abstract

One of the aims of this research is to create a system with high mitochondrial oxidative stress. This was done by knocking down Superoxide dismutase 2 using RNA interference technology in Drosophila melanogaster. This knocking down would result in a decreased efficiency of the flies to dismutate superoxide and thus resulting in high superoxide levels. The consequences of such a system whose conditions are similar to that seen in late-life stages were studied. According to the Mitochondrial Free Radical Theory of Aging (MFRTA) the damage caused by ROS produced during normal metabolism is determinant of aging. The validity of MFRTA was checked in this system. Also from previous work, it is known that alternative enzymes NDI1 and AOX reduce ROS production and that NDI1 extends lifespan in flies. The mechanism by which NDI1 extends lifespan was not clear. We set out to investigate how NDI extends lifespan by coexpressing NDI1 and AOX in the flies expressing SOD2 RNAi using a binary system GAL4/UAS. NDI1 was previously found to decrease ROS production as well as increase complex I specific substrate oxidation. Here we try to find if NDI1 functions by a ROS dependent or independent method to extend lifespan. The alternative enzyme AOX was expressed in parallel to be used as a control due to its location in the electron transport chain (ETC) and its complementation of complex III as opposed to NDI1 which compliments complex I of the ETC.