Abstract:Superoxide dismutase (SOD), the first barrier of antioxidation, protects cells through the removal of excessive superoxide. However, little is known about the function of SOD genes in Odontobutis potamophila. In the present study, the rapid amplification of cDNA ends (RACE) approach and quantitative real-time PCR were used to clone the full-length cDNA of Mn-SOD and analyze its expression patterns. The full length of cDNA Mn-SOD was 1008 bp, including an open reading frame (ORF) of 678 bp, a 5¢-untranslated regions (UTR) of 15 bp and a 3¢UTR of 315 bp. Each 3¢UTR possessed a polyadenylation signal sequences of AATAAA and a poly A tail of 31 bp, a phenomenon that vertebrate usually has. It was speculated that the sequence encoded 225 amino acids. The Mn-SOD genes contains two conserved domains: the Sod_Fe_N (28-109) and Sod_Fe_C (116-219). The structure was similar with other species, which showed that the gene was conserved in the evolution. The homologous comparison with other species revealed that the Mn-SOD had the highest sequence identity with Oplegnathus fasciatus and Channa striatawhich, about 90.3 %. Quantitative real-time PCR was used to quantify the tissue-specific expression of Mn-SOD gene. Predominant expression of Mn-SOD was detected in muscle. Different developmental stages from embryo to larva had Mn-SOD gene expressed. Morula stage had the highest expression level. In addition, the expression levels of Mn-SOD mRNA in liver increased initially and then declined after the exposure of NaNO2. In gill, the mRNA expression levels of Mn-SOD fluctuated significantly. The findings of this study suggested that the Mn-SOD may play an important role in defending oxidative stress and cellular damage induced by nitrite, by detoxifying harmful reactive oxygen. Our study provides valuable reference to optimize the artificial breeding and rearing conditions of O.potamophila.
