Oxygen radical metabolism in Drosophila melanogaster

F. Missirlis & H. Jäckle

Dep. of Molecular and Developmental Biology, Max-Planck-Institut für biophysikalische Chemie, Am Fassberg 11, Göttingen 37077, Germany

Reactive oxygen species (ROS) in cells are formed in response to high oxygen levels. They cause lipid peroxidation, DNA damage and protein modifications, referred to as oxidative stress. Insects, like all aerobic organisms, possess antioxidant enzymes which protect the cells against the toxicity of ROS. We use Drosophila melanogaster as a model system to investigate the function of the antioxidant enzymes superoxide dismutase (SOD), catalase (Cat), glutathione peroxidase (Gpx) and glutathione reductase (Gr) in vivo, and we address the role of ROS. We have cloned Drosophila homologues of Gpx and Gr. We have examined the expression profile of the enzymes SOD, Cat, Gpx and Gr, which are thought to function in all cells. We found that they are expressed in spatially restricted patterns during embryogenesis. We have also generated transgenic flies, by P-element- mediated transformation, bearing an extra copy of the gpx1 locus. Homogenates from transgenic flies showed increased Gpx activity. These flies were found to be more resistant to acute oxidative stress (feeding with paraquat; exposure to 100% O 2 levels) than the wild type controls. Similar results were obtained in response to transgene-derived overexpression of Gpx1 from a gpx1 cDNA that was placed under the control of an inducible promoter. In contrast, Gpx1 overexpression in SOD mutants caused lethality. SOD null mutants are semilethal, i.e. only 20% of the flies hatch from the pupal case. However, if such mutants carry an extra copy of gpx1, they fail to hatch. Possible explanations of these phenomena will be discussed.

More Topics on the Wing

About Us