Nitrite levels are generally high in high-density aquaculture. Nitrite is a potential stress-inducing factor and can cause oxidative stress because excessive reactive oxygen species (ROS) formation through nitrite induction cannot be scavenged by the endogenous antioxidant system, thus leading to cell damage or death. Manganese Superoxide Dismutase (MnSOD) is a highly efficient endogenous ROS scavenger that quenches mitochondrial ROS and protective against oxidative stress. To enhance the efficiency of MnSOD in removing ROS and reducing oxidative caused by nitrite, in this study, we cloned grouper MnSOD (gMnSOD) fused with a cell-penetrating peptide, TAT, to construct a TAT-gMnSOD fusion protein and assessed its potential to eliminate excess ROS induced by high nitrite concentrations and enhance the resistance of zebrafish to environmental stressors. Our results revealed that TAT-gMnSOD penetrated the grouper fin (GF-1) cells, scavenged nitrite-induced intracellular ROS, and enhanced cell viability on NaNO₂ treatment. Furthermore, pretreatment of zebrafish with TAT-gMnSOD fusion protein reduced the MDA content and increased the survival rate. In addition, the TAT-gMnSOD fusion protein reduced 2-phenoxyethanol toxicity and attenuated excessive anesthesia among zebrafish. In conlusion, our cell-permeable TAT-gMnSOD fusion protein effectively counters oxidative stress, prevents environmental stress-induced damage, and increases aquaculture benefits.

高密度水产养殖中的亚硝酸盐水平通常较高。亚硝酸盐是一种潜在的应激诱导因子，可引起氧化应激，因为通过亚硝酸盐诱导形成的过量活性氧（ROS）不能被内源性抗氧化系统清除，从而导致细胞损伤或死亡。锰超氧化物歧化酶 (MnSOD) 是一种高效的内源性 ROS 清除剂，可淬灭线粒体 ROS 并防止氧化应激。为了提高 MnSOD 在去除 ROS 和减少亚硝酸盐引起的氧化方面的效率，在本研究中，我们克隆了与细胞穿透肽 TAT 融合的石斑鱼 MnSOD (gMnSOD)，构建 TAT-gMnSOD 融合蛋白并评估其消除高亚硝酸盐浓度诱导的过量 ROS 和增强斑马鱼对环境压力源的抵抗力的潜力。我们的研究结果表明，TAT-gMnSOD 穿透石斑鱼鳍 (GF-1) 细胞，清除亚硝酸盐诱导的细胞内 ROS，并增强 NaNO 上的细胞活力₂治疗。此外，用 TAT-gMnSOD 融合蛋白预处理斑马鱼可降低 MDA 含量并提高存活率。此外，TAT-gMnSOD 融合蛋白降低了斑马鱼的 2-苯氧乙醇毒性并减轻了过度麻醉。总之，我们的细胞渗透性 TAT-gMnSOD 融合蛋白可有效对抗氧化应激，防止环境应激引起的损害，并增加水产养殖效益。