Mitochondrial manganese superoxide dismutase knock-down increases oxidative stress and caspase-3 activity in the white shrimp Litopenaeus vannamei exposed to high temperature, hypoxia, and reoxygenation

Abstract

Shrimp are increasingly exposed to warmer temperatures and lower oxygen concentrations in their habitat due to climate change. These conditions may lead to oxidative stress and apoptosis. We studied the effects of high temperature, hypoxia, reoxygenation, and the combination of these factors on lipid peroxidation, protein carbonylation, and caspase-3 activity in gills of white shrimp Litopenaeus vannamei. Silencing of mitochondrial manganese superoxide dismutase (mMnSOD) was used to determine the role of this enzyme in response to the abiotic stressors described above, to avoid oxidative damage and apoptosis. In addition, mMnSOD gene expression and mitochondrial SOD activity were evaluated to determine the efficiency of silencing this enzyme. The results showed that there was no effect of the abiotic stress conditions on the thiobarbituric acid reactive substances (TBARS), but protein carbonylation increased in all the oxidative stress treatments and caspase-3 activity decreased in hypoxia at 28 °C. On the other hand, mMnSOD-silenced shrimp experienced higher oxidative stress, since TBARS, carbonylated proteins and caspase-3 activity increased in some silenced treatments. Unexpectedly, mitochondrial SOD activity increased in some of the silenced treatments as well. Altogether, these results suggest that mMnSOD has a key role in shrimp for the prevention of oxidative damage development and induction of apoptosis in response to hypoxia, reoxygenation, high temperature, and their interactions, as conditions derived from climate change.

Keywords: Hypoxia; MnSOD; Oxidative biomarkers; Oxidative stress; RNAi; Shrimp; Temperature.