摘要
为探究金钱鱼（Scatophagusargus）MHCⅡβ基因的结构和特性，采用同源克隆和RACE等技术，在获得cDNA全序列的基础上，分析其内含子序列、基因多态性和组织表达情况。结果表明，金钱鱼MHCⅡβ基因cDNA序列全长1172bp，其中5＇UTR长34bp，3＇UTR长388bp，开放阅读框（ORF）长750bp，编码249个氨基酸，包含信号肽、B1结构域、p2结构域、连接肽（CP）、跨膜区（TM）和胞质区（cYT）；MHCⅡβ基因由6个外显子和5个内含子组成，其中内含子3将p2结构域分开。从43尾金钱鱼的209个有效克隆中，获得209条不同的核苷酸序列，可归为48个等位基因主型，分别命名为Scar-DXB＊0101～Scar-DXB＊4801，揭示金钱鱼MHCⅡβ基因的多态性很丰富。RT-PCR检测发现，金钱鱼MHCIIB基因在所检测的11种组织中均有表达，其中在脾、鳃、肠和皮肤中表达量较高，在肾、胃、心脏表达量中等，而在眼、脑、肝、肌肉中表达量较低。对健康金钱鱼人工感染嗜水气单胞菌后，发现其MHCIID基因在肝、脾、鳃、肾等组织中的表达量均发生了不同程度的变化，证明该基因在金钱鱼免疫反应中有重要作用。在NJ法构建的系统树中，金钱鱼与舌齿鲈、大西洋鲑等硬骨鱼类的亲缘关系相对较近，而与铰口鲨、原鸡、小鼠、人等的亲缘关系则依次渐远。
Abstract： The major histocompatibility complex （MHC） is a gene family common to vertebrates and is encoded by a group of genes closely related to immunological functions. Many studies have indicated that MHC occurs on the sur- face of all karyocytes and that the MHC Ⅱ genes of fish differ by species in structure, character, and polymorphisms. The spotted scat （Scatophagus argus） is eurythermic and euryhaline and is widely distributed in brackish water and ma- rine habitats of the Indo-Pacific region. Spotted scat has become an economically important species in southern China in recent years owing to its strong tolerance to a variety of environmental conditions. However, most spotted scat stud- ies in the last two decades have focused on artificial breeding, biological characteristics, gonadal development, repro- ductive characteristics, and genes related to osmotic adjustment and gonadal development, but not immune system function. Furthermore, farmers have recently found that spotted scat are susceptible to infections by parasites, bacteria, and viruses, which could cause serious economic losses. Thus, we determined the complete cDNA sequence of the spotted scat MHC-II~ gene for the first time using homology-based cloning and rapid amplification of cDNA ends po- lymerase chain reaction （RACE-PCR） and analyzed the introns, gene polymorphisms, and tissue expression. As results, the cDNA sequence of the spotted scat MHC-Ⅱβ gene was 1172 bp in length, including a 34 bp 5＇-untranslated region （UTR）, a 388 bp 3＇-UTR, and a 750 bp open reading frame （ORF）. The ORF contained the signal peptide, the β1 do- main, the 132 domain, a connecting peptide, a transmembrane region, and a cytoplasmic tail. The total length of the gene was 2920 bp. The MHC-Ⅱβ gene contained six exons and five introns （85-1010 bp）, and the third intron separated the 132 domain into two parts. This structure differs from some other teleosts and provides new evidence for the lack of conservation of MHC-Ⅱβ gene
出处
《中国水产科学》
CAS
CSCD
北大核心
2016年第1期21-33,共13页
Journal of Fishery Sciences of China
基金
国家自然科学基金项目(41176109)
关键词
金钱鱼
MHC
Ⅱβ基因
基因结构
多态性
组织表达
Scatophagus argus
MHC Ⅱβ gene
genomic structure
polymorphism
tissue expression
