Functional characterisation of the antioxidant system in Drosophila melanogaster, after metals exposure.

Reactive oxygen species (ROS) are a normal byproduct of aerobic metabolism playing an important role in cell signaling and immunity when their production is regulated or controlled by antioxidant enzymes. Reduced expression and/or activity of these proteins lead to an excess of ROS production and oxidative stress, accelerating aging and neurodegeneration. For example, amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease caused by motoneuron loss and some familial cases (fALS) are linked to mutations of superoxide dismutase type-1 (SOD1). Many animal models, such as Drosophila melanogaster, are used as useful tool to study this disease, focusing the attention on the different mutant SOD1s but not considering the complex relationships of functional complementarity between SOD1 and the other components of the enzymatic antioxidant system. In the present work we study, for the first time, the gene expression, by qRT-PCR, of SOD1 together with that of superoxide dismutase type-2, catalase, glutathione peroxidases and peroxiredoxins in wild type D. melanogaster, exposed to various concentration of copper or cadmium, used as pro-oxidants. The aim was to determine the adequate experimental condition to employ with D. melanogaster SOD1 mutants. On the basis of our results, copper is the major inducer of all considered enzymes, and the dose of 1.0 mM seems to be the more suitable. Catalase is temporally co-expressed with SOD1, at least in males and the gene expression of other enzymes seems to be temporally uncorrelated to SOD1. Other important indication will be obtained by biochemical quantification of activity for all considered enzymes and the evaluation of ROS production, that are now in progress.