摘要
锰超氧化物歧化酶(MnSOD)是一种含金属辅基的抗氧化酶,广泛存在于各种需氧生物中,能将氧自由基快速歧化为分子氧(O_2)和过氧化氢(H_2O_2)。本研究首次获得了黄姑鱼MnSOD基因的cDNA序列,其全长958 bp,包括47 bp的5′端非编码区(untranslated region,UTR)、233 bp的3′UTR和678 bp的开放阅读框(open reading frame,ORF),编码225个氨基酸残基(aa)。氨基酸序列分析显示,MnSOD含有一条信号肽序列(1~27 aa),4个Mn结合位点(His 53、101、190和Asp 186)和一条保守的锰/铁SOD特征序列(186~193 aa)。系统进化树分析显示,黄姑鱼MnSOD在进化上与大黄鱼最近,并与其他鱼类(斜带石斑鱼、暗纹东方鲀、牙鲆、斑马鱼和日本鳗鲡)聚为一支。荧光定量PCR检测显示,MnSOD基因在所检测的11个黄姑鱼组织/器官中均有表达,其中心脏中表达量最高,其次为脑、肝脏、鳃、中肾、肠、胃、头肾、肌肉和鳔,在脾脏中表达量最低。氨氮和亚硝态氮对黄姑鱼的急性毒性实验显示,黄姑鱼对氨氮胁迫更为敏感,其氨氮和亚硝态氮的96 h半致死浓度(LC50)分别为20.23 mg/L (换算成非离子氨0.57 mg/L)和99.08 mg/L,安全浓度分别为2.02 mg/L (换算成非离子氨0.06 mg/L)和9.91 mg/L。此外,黄姑鱼经氨氮和亚硝态氮急性攻毒后,其肝脏、鳃和头肾中MnSOD基因的表达水平均不同程度上调,推测MnSOD的上调是为了及时清除由氨氮和亚硝态氮刺激产生的氧自由基,或可用作水体污染检测的早期生物标志物。
Manganese superoxide dismutase(MnSOD),a transition-metal-containing antioxidant enzyme that dismutates the superoxide radicals to either ordinary molecular oxygen(O2)or hydrogen peroxide(H2O2),widely existed in many aerobic organisms.In this study,the cDNA of MnSOD,identified from Nibea albiflora,was 958 bp in length including 5′-untranslated region(UTR)of 47 bp,3′-UTR of 233 bp and an open reading frame(ORF)of 678 bp encoding a polypeptide of 225 amino acids.The deduced amino acid sequence analysis showed that MnSOD contains a putative signal peptide in the N-terminus(1-27 aa),four Mn binding sites(His 53,101,190 and Asp 186)and a Mn/Fe SOD signature sequence(186-193 aa).Phylogenetic tree analysis indicated that N.albiflora has the closest relationship with Larimichthys crocea,and was classified into the same cluster with other teleosts(Epinephelus coioides,Takifugu fasciatus,Paralichthys olivaceus,Danio rerio and Anguilla japonica).Quant-itative real-time qRT-PCR analysis showed that the mRNA transcripts of MnSOD were detected in all examined tissues and the predominant distribution was in heart,followed by brain,liver,gill,kidney,intestine,stomach,head-kidney,muscle and swim bladder,and the minimum level was displayed in spleen.Moreover,during the acute toxic experiment of ammonia nitrogen or nitrite nitrogen,N.albiflora showed more sensitive to ammonia nitrogen,and the 96 h median lethal concentration(LC50)value was found to be 20.23 mg/L for ammonia nitrogen(or 0.57 mg/L for non-ionic ammonia)with safe concentration(SC)values of 2.02 mg/L(or 0.06 mg/L for non-ionic ammonia)and 99.08 mg/L with SC of 9.91 mg/L for nitrite nitrogen,successively.Furthermore,the temporal expression of MnSOD was significantly up-regulated in the liver,gill and head-kidney of N.albiflora.The expression features of the MnSOD suggested its important role in scavenging oxygen free radicals caused by ammonia nitrogen/nitrite nitrogen and could be used as an early biomarker for detection of environmental pollu-tion.
作者
王小龙
宋青
王志勇
韩芳
WANG Xiaolong;SONG Qing;WANG Zhiyong;HAN Fang(Key Laboratory of Healthy Mariculture for the East China Sea,Ministry of Agriculture and Rural Affairs,Fisheries College,Jimei University,Xiamen 361021,China;Institute of Flexible Electronics,Northwestern Polytechnical University,Xi’an 710072,China)
出处
《水产学报》
CAS
CSCD
北大核心
2019年第4期820-832,共13页
Journal of Fisheries of China
基金
国家海水鱼类产业技术体系专项(CARS-47-G04)
福建省科技厅重大专项(2018N5010)
福建省自然科学基金(2018J01450
2019J01693)~~