Molecular and expression analysis of manganese superoxide dismutase (Mn–SOD) gene under temperature and starvation stress in rotifer Brachionus calyciflorus

Superoxide dismutase (SOD) is an important antioxidant enzyme that protects organs from damage by reactive oxygen species. We cloned cDNA encoding SOD activated with manganese (Mn–SOD) from the rotifer Brachionus calyciflorus Pallas. The full-length cDNA of Mn–SOD was 1,016 bp and had a 669 bp open reading frame encoding 222 amino acids. The deduced amino acid sequence of B. calyciflorus Mn–SOD showed 89.1, 71.3, and 62.1 % similarity with the Mn–SOD of the marine rotifer Brachionus plicatilis, the nematode Caenorhabditis elegans, and the fruit fly Drosophila melanogaster, respectively. The phylogenetic tree constructed based on the amino acid sequences of Mn–SODs from B. calyciflorus and other organisms revealed that this rotifer is closely related to nematodes. Analysis of the mRNA expression of Mn–SOD under different conditions revealed that expression was enhanced 5.6-fold (p < 0.001) at 30 °C after 2 h, however, low temperature (15 °C) promoted Mn SOD temporarily (2.5-fold, p < 0.001) and then decreased to normal level (p > 0.05). Moderate starvation promoted Mn–SOD mRNA expression (p12 < 0.01, p36 < 0.05), which reached a maximum value (15.3 times higher than control, p24 < 0.01) at 24 h. SOD and CAT activities also elevated at the 12 h–starved group. These results indicate that induction of Mn–SOD expression by stressors likely plays an important role in aging of B. calyciflorus.