作　　者： ; ; ; ; ; ; ;

机构地区： 中国水产科学研究院珠江水产研究所

出　　处： 《农业生物技术学报》 2016年第10期1588-1599,共12页

摘　　要： β2-微球蛋白（β2-microglobulin,β2m）是主要组织相容性复合体（major histocompatibility complex,MHC）Ⅰ分子的亚基之一,与MHC-Iα链非共价结合构成MHCⅠ分子。本实验通过反转录PCR（RT-PCR）和c DNA末端快速扩增技术（rapid-amplification of c DNA ends,RACE）克隆了尼罗罗非鱼（Oreochromis niloticus）β2m基因的全长c DNA序列及基因组序列,并对c DNA多态性、m RNA组织分布及感染链球菌后表达的变化进行了分析。结果共获得尼罗罗非鱼2条β2m基因c DNA,全长分别为900和906 bp。两c DNA均包括351 bp的ORF,共编码116个氨基酸残基,还包含68 bp的5＇非编码区（5＇-UTR）和486（492）bp的3＇-UTR。两条c DNA对应各自不同的基因组序列。基因组序列分析发现,β2m基因含3个外显子和2个内含子。尼罗罗非鱼β2m基因推测氨基酸序列与其他物种的β2m基因相似性在39.20%-89.80%之间。β2m基因c DNA多态性分析表明,尼罗罗非鱼中共有2种不同类型的β2m c DNA,每种类型c DNA又有3种不同的亚型。定量PCR分析表明,β2m基因在尼罗罗非鱼脾脏、心脏和肾脏中表达量最高,鳃与肠中的表达量较高,在皮肤和肌肉中的表达量最低。腹腔注射无乳链球菌（Streptococcus agalactiae）后,尼罗罗非鱼β2m m RNA表达量在4个所检测组织（鳃,肾脏,心脏和脾脏）中均出现了先上升后下降的变化趋势。本实验结果表明,β2m基因可能参与尼罗罗非鱼的免疫应答,在免疫反应中发挥重要功能。本研究有助于进一步了解尼罗罗非鱼的免疫调节机制和更好地理解鱼类β2m的生理功能。 β2-microglobulin（β2m） is one of the subunits of classⅠmajor histocompatibility complex（MHCⅠ）molecular, which binds non-covalently with the α-chain of the MHC-Ⅰ molecular. Based on the RT-PCR and RACE-PCR, full-length c DNA of β2m was cloned from Nile tilapia（Oreochromis niloticus）. In addition, c DNA polymorphism and the m RNA expression pattern were analyzed. The results showed that the two β2m c DNAwas 900 and 906 bp in length, respectively, including an open reading frame（ORF） of 351 bp encoding a polypeptide of 116 amino acids. The 5＇- UTR and 3＇- UTR was 68 nts and 486（492） nts respectively. The two c DNA had different genomic sequence, but they all had 3 exons and 2 introns. The putative protein of the 2 β2m had 92.3% identity. The putative amino acid sequence of β2m had 39.20%~89.8% identity with those of other teleost and mammals. The putative protein of the 2 β2ms exhibited the highest identity with zebra mbuna（Maylandia zebra）（89.80% and 84.7%, respectively）. The 2 β2ms had 63.2% and 60.70% identity with catfish（Ictalurus punctatus） respectively. And β2m-2 had the lowest identity with chicken（Gallus gallus） and mouse（Mus musculus）（39.50% and 39.20%, respectively）. Predictprotein online analysis found that the 2 β2m all had the typical immunoglobulin（Ig） and major histocompatibility complex protein（MHC） signature Yx Cx Vx H.The phylogenetic tree showed that the β2ms of Nile tilapia clustered with zebra mbuna first, then clustered with orange- spotted grouper（Epinephelus coioides）, large yellow croaker（Pseudosciaena crocea）, and seabass（Dicentrarchus labrax）, and then clustered with other teleost and mammals. In addition, the rainbow trout（Oncorhynchus mykiss）, catfish, zebrafish（Brachydanio rerio）, and grass carp（Ctenopharyngodon idella） formed a subcluster. The Atlantic cod（Gadus morhua）, red seabream（Parus major）, and flounder（Paralichthys olivaceus） formed another subcluster. The chicken, huma

关 键 词： 尼罗罗非鱼 微球蛋白基因 分子多态性 组织表达

领　　域： [农业科学]