双须骨舌鱼卵黄蛋白受体基因(vtgr)组织表达及生物信息学分析

为探究卵黄蛋白受体(Vitellogenin receptor,Vtgr)在双须骨舌鱼性腺发育的作用及组织表达规律,本研究运用RACE技术首次克隆获得双须骨舌鱼vtgr cDNA全序列,该序列全长为2 841 bp,开放阅读框(ORF)为2 556bp,编码氨基酸851个,5'端非编码区26 bp,3'端非编码区258 bp。生物信息学分析显示,vtgr蛋白分子质量为93.6 ku,等电点为4.78,含有8个低密度脂蛋白受体A结构域(LDLa),5个低密度脂蛋白受体YWTD结构域(LY),2个类表皮生长因子结构域(EGF),1个钙结合类表皮生长因子结构域(EGF-CA),1个跨度为23个氨基酸的跨膜结构域,属于极低密度脂蛋白受体(vldlr),是亲水性跨膜蛋白。多序列比对分析表明,双须骨舌鱼vtgr高度保守,与美丽硬仆骨舌鱼(Scleropages formosus)相似度最高为95.96%。系统进化树分析发现,与美丽硬仆骨舌鱼聚为一支,与鲽形目、鲤形目、鲑形目亲缘性较远。qRT-PCR结果分析发现,双须骨舌鱼vtgr在雌雄鱼的8个不同组织中均有表达,在卵巢和精巢中的相对表达量显著高于鳃、肝、脾、心脏、头肾、脑等组织(P0.05)。此外,vtgr在雌雄鱼性腺发育Ⅱ、Ⅲ和Ⅳ期表达分析表明,在卵巢中vtgr相对表达量依次递减,且Ⅱ期显著高于Ⅲ和Ⅳ期(P0.05);精巢中3个时期vtgr表达无显著差异(P0.05),但Ⅱ和Ⅲ期表达量显著低于卵巢(P0.05)。研究表明,vtgr基因编码区序列有较高保守性。Vtgr在双须骨舌鱼前期卵巢发育中发挥着重要作用。

The tissue expression and bioinformatics analysis for vitellogenin receptor gene ( vtgr) of Osteoglossum bicirrhosum

The complete nucleotide sequence of vtgr cDNA was obtained by RACE in this research to investigate the effect of vitellogenin receptor (Vtgr) on the gonadal development of Osteoglossum bicirrhosum and its regularity of tissue expres-sion.The sequence length was 2 841 bp.The open reading frame (ORF) was 2 556 bp, encoded amino acid was 851, 5' and 3' end non-coding region were 26 bp and 258 bp respectively.Bioinformatics analysis showed that the protein molecu-lar weight of Vtgr was 93.6 ku and the isoelectric point was 4.78.The ORF contained eight low density lipoprotein receptor A domains ( LDLa), five low density lipoprotein receptor YWTD domains ( LY), two epidermal growth factor domain ( EGF), a calcium-binding epidermal growth factor domain (EGF-CA), a transmembrane domain with a span of 23 a- mino acids.It was a hydrophilic transmembrane protein and belonging to the very low density lipoprotein receptor (vldlr) . The results of multiple sequence analysis showed that the vtgr of O.bicirrhosum was highly conserved and had the highest similarity of 95.96% with Scleropages formosus.Phylogenetic tree analysis showed that O.bicirrhosum clustered with Scler-opages formosus and was far more affinity with Heterosomata, Cypriniformes, Salmoniformes The results of Qrt -PCR showed that vtgr of O.bicirrhosum was expressed in eight different tissues of males and females.The relative expression in o-vary and testis was significantly higher than that in gill, liver, spleen, heart, head kidney, brain and other organizations (P<0.05) .In addition, the expression of vtgr in male and female gonadal development Ⅱ, Ⅲ and Ⅳ showed that the relative expression of vtgr in the ovary was decreased and the expression in phase Ⅱ was significantly higher than that in stage Ⅲ and Ⅳ(P<0.05) .There was no significant differences in the three stages of testis (P>0.05) .However, the expressions in testis of stageⅡ and Ⅲ were significantly lower than those of ovaries (P<0.05) .In conclusion, this study showed that the sequence of vtgr encoding region had a higher conservatism and Vtgr played an important role in the devel-opment of the ovary in the early stage of O.bicirrhosum.