尼罗罗非鱼NITR基因的克隆鉴定与组织表达分析

摘要

The encoding sequence of NITR(Novel immune-type receptor)gene(GenBank accession number :KX989509 ;designated as On-NITR)was cloned from the spleen of Nile tilapia(Oreochromis niloticus). The complete cDNA sequence of On-NITR gene was 1119 bp with an ORF of 1026 bp encoding 341 amino acids. The deduced amino acid sequence of On-NITR had an estimated molecular weight of 37.38 kD and a theoretical pI of 8.28. Through NCBI BLAST,we found the amino acid sequence identities between On-NITR and previously reported fish NITRs were approximately 27% - 46%. Amino acid alignment indicated that On-NITR consisted of one typical signal peptide,two extracellular immunoglobulin(Ig)domains(V and V/C2),one transmembrane domain,and one highly conserved the cytoplasmic region with an immunoreceptor tyrosine-based inhibitor motif(ITIM)and an ITIM-like motif(itim). Moreover,the analysis by real time quantitative PCR revealed that the expression of On-NITR was detected in all examined tissues of a healthy Nile tilapia with the higher expression level in intestine,skin and liver,while lower expression in thymus,gill,spleen,heart,and brain as well as the lowest level in head and kidney.%从尼罗罗非鱼脾脏组织中克隆获得新型免疫受体(NITR,Novel immune-type receptor)基因的编码区序列(GenBank登录号:KX989509;命名为On-NITR),该基因cDNA全长1119 bp,ORF为1026 bp,可编码341个氨基酸,理论分子量为37.38 kD,等电点为8.28.通过NCBI BLAST比对发现罗非鱼NITR与其他已报道的物种NITR氨基酸序列相似度为27%-46%.氨基酸序列分析显示:On-NITR具有1个信号肽区域、2个胞外Ig-domain区、1个跨膜结构域,以及1个胞质尾区,该胞质尾区含有NITR典型的免疫受体酪氨酸抑制基序(ITIM)和一个ITIM类似基序itim,且具有较高的保守性.荧光定量PCR分析显示,On-NITR在健康尼罗罗非鱼组织中均有表达,在肠道、皮肤、肝脏表达水平较高,在胸腺、鳃、脾脏、心脏、脑组织中的表达量较低,在头肾组织中的表达量最低.