三角帆蚌BPI/LBP基因cDNA的分子特征及表达分析

Molecular Characteristics and Expression Analysis of BPI/LBP Gene cDNA from Hyriopsis cumingii

杀菌通透性增加蛋白/脂多糖结合蛋白(bactericidal permeability-increasing protein/LPS-binding protein,BPI/LBP)在生物体的免疫应答过程中发挥着重要作用,但是在三角帆蚌中未见其相关的研究。我们采用RACE法获得三角帆蚌BPI/LBP基因c DNA全长(Gen Bank KX363568),该基因序列全长为1 793 bp,5'非编码区(untranslated region,UTR)和3'UTR分别为65 bp和219 bp,开放阅读框(open reading frame,ORF)1 509 bp,共编码氨基酸502个。氨基酸序列包括BPI1和BPI2两个结构域,同源性分析其与一些已知物种的BPI/LBP基因氨基酸发现各物种间具有相似的结构域,属于典型的BPI/LBP基因。q RT-PCR(Quantitative Real-time PCR)分析结果表明BPI/LBP基因表达于血液、肠、肾脏、外套膜、肝、腮、闭壳肌、性腺和斧足9个正常组织,表达量最高的是血液,最低的是肝脏。利用嗜水气单胞菌诱导后检测发现,血液、外套膜变化趋势最为明显,均呈现出先升高再降低的趋势,在3 h或12 h达到最大值,之后开始逐渐下降并趋于稳定,我们推测BPI/LBP基因在三角帆蚌的免疫反应中发挥着重要的作用。

Bactericidal permeability increasing protein and lipopolysaccharide binding protein（BPI/LBP） is very important in the immune reaction of biological body,but the study of BPI/LBP gene has been rarely reported in Hyriopsis cumingii.In this study,the full length of c DNA sequence of BPI/LBP gene was obtained from H.cumingii（Genbank KX363568） by RACE.It was 1 793 bp,containing 5＇ untranslated region（UTR） of 65 bp,3＇UTR of 219 bp,and an ORF of 1 509 bp encoding 502 amino acids.The amino acid sequence contained two protein domains of BPI1 and BPI2.The result of homology analysis showed that it has a few of similarity with other species,which suggested that this gene belongs to the typical BPI/LBP gene.Quantitative Real-time PCR dedicated that BPI/LBP gene expressed in a wide range of tissues including the blood,intestines,kidney,mantle,liver,gill,adductor,gonad,foot.The highest expression of BPI/LBP was in blood,on the contrary,the lowest in liver.After being infected with Aeromonas hydrophila,the expression of BPI/LBP had significant change trend in blood and mantle.It presented that the expression of BPI/LBP in mantle increased to the highest value at 3 h and decreased and then stabilized,which showed the similar tendency with the expression of BPI/LBP in blood.The difference was that the highest value of the expression of BPI/LBP in blood was at 12 h.We speculated that BPI/LBP gene plays an important role in the immune reaction of Hyriopsis cumingii.