Expression of Superoxide Dismutase from the Desert Beetle <i>Microdera Punctipennis</i> Enhances Cold Tolerance in <i>Drosophila Melanogaster</i>

BACKGROUND: SODs are key enzymes that degrade the superoxide radical, representing a primary defense in the antioxidant system against the toxicity caused by overproduction of ROS under environmental stresses. However, there is scarce data about SOD functions in insects under low temperature. OBJECTIVE: In this research, we investigated whether the heterologous superoxide dismutase overexpression in Drosophila melanogaster improves cold tolerance in flies. MATERIALS AND METHODS: A novel extracellular copper/zinc SOD ( MpSOD3 ) from the desert beetle Microdera punctipennis was transferred to D. melanogaster via P-element-mediated transformation. The protection effect of increased SOD activity on lipid peroxidation and apoptosis were determined by measuring oxidative parameters and TUNEL assay during cold treatment. RESULTS: Compared to non-transgenic flies exposed to 0°C treatment for 12-24 h period, the expression level of MpSOD3 and SOD activity were significantly higher in all transgenic lines with less accumulation of superoxide(O 2 • - ). MpSOD3 expressing Drosophila exhibited higher survival rates compared with the control under cold and oxidative exposure. In response to cold, the MDA content and TUNEL assay showed that MpSOD3 expressing adult flies exhibited less lipid peroxidation and apoptotic damage in comparison to control flies. CONCLUSION: Collectively, these results indicate that the overexpression of MpSOD3 in transgenic Drosophila lines enhances cold tolerance by eliminating O 2 • - and lessening over-oxidation of the cellular membrane system.