尼罗罗非鱼NITR基因的克隆鉴定与组织表达分析

Cloning and Tissue Expression Analysis of NITR in Nile Tilapia(Oreochromis niloticus)

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(Gen Bank登录号:KX989509;命名为On-NITR),该基因c DNA全长1 119 bp,ORF为1 026 bp,可编码341个氨基酸,理论分子量为37.38k D,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。

The encoding sequence of NITR （ Novel immune-type receptor） gene （ GenBank accession number ： KX989509 ; designated as On-NITR ） was eloned from the spleen of Nile tilapia （ Oreochromis niloticus ） . The complete cDNA sequence of On-NITR gene was 1 119 bp with an ORF of 1 026 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.