黄河高原鳅血红蛋白基因家族全基因组分析及低氧胁迫响应

GENOME-WIDE ANALYSIS OF THE TRIPLOPHYSA PAPPENHEIMI HEMOGLOBIN GENE FAMILY AND ITS RESPONSE TO HYPOXIA STRESS

  • 摘要: 为探究血红蛋白基因家族在黄河高原鳅(Triplophysa pappenheimi)低氧适应中的作用, 研究基于黄河高原鳅基因组数据对血红蛋白基因家族进行了生物信息学分析, 并开展低氧胁迫和基因表达检测。结果显示, 黄河高原鳅血红蛋白基因家族由11个成员组成, 其中包括6个α珠蛋白基因(hbaa1hbaa2hbae1hbae3hbae4hbae5)和5个β珠蛋白基因(hbba1hbba2hbbe1.1hbbe1.2hbbe2)。Motif、Domain 及基因结构分析结果均表明该家族成员具有较高的保守性, 除hbbe2外, 其余基因结构相似。染色体定位分析结果显示, 血红蛋白基因家族成员分布在2条染色体上(Chr_07、Chr_17)。蛋白理化性质分析结果显示, 除hbbe1.2为疏水性不稳定蛋白, 其余基因产物均为疏水性稳定蛋白, 其中hbae3hbbe1.1hbbe2为酸性蛋白; 其余8个为碱性蛋白, 其中α-螺旋是主要的二级结构。亚细胞定位预测结果显示, 除hbae4基因产物位于细胞质中, hbae3位于细胞质和细胞外; 其余血红蛋白基因均位于线粒体中。基因表达研究表明, 在急性低氧胁迫12h (0.3±0.1 mg/L)后, hbaa1、hbaa2、hbba1hbba2基因在肝脏、鳃和血液中的表达量具有上调趋势, 但是差异不显著(P<0.05); 在慢性低氧24h至96h (3.0±0.1 mg/L)时, hbaa1hbba1hbaa2hbba2基因在肝脏和血液中的表达量达到峰值(P<0.05), 随着胁迫时间延长, 上述基因的表达量均有所下调。在鳃组织中, hbaa1、hbaa2hbba1的最高表达量出现在慢性低氧后的196h, 而hbba2基因表达峰值出现在24h。研究展示了黄河高原鳅血红蛋白基因家族成员的低氧胁迫表达模式, 为黄河高原鳅的低氧适应机制研究积累科学数据。

     

    Abstract: Triplophysa pappenheimi is a representative species of Nemacheilinae, which can adapt to the aquatic environment of Tibetan Plateau. To investigate the role of hemoglobin gene family in T. pappenheimi adaptation to hypoxia, bioinformatics analysis of hemoglobin gene family was performed based on genome data, followed by an examination of expression changes of hemoglobin genes in response to hypoxia. The hemoglobin gene family to T. pappenheimi consists of 11 members, including six α-globin genes (hbaa1, hbaa2, hbae1, hbae3, hbae4, and hbae5) and five β-globin genes (hbba1, hbba2, hbbe1.1, hbbe1.2, and hbbe2). Motif, domain, and gene structure analysis showed high conservation among these genes; with the exception of hbbe2, the others exhibited similar structure features. Chromosomal localization analysis showed that the members of hemoglobin gene family were distributed on two chromosomes (Chr_07 and Chr_17). The results of physicochemical analysis indicated that all the gene products were stable hydrophobic proteins, except hbbe1.2, among which, hbae3, hbbe1.1, and hbbe2 were classified as acidic proteins, and the other eight were basic proteins, with α-helix is the main secondary structure. Subcellular localization prediction showed that hbae3 and hbae4 were located in the cytoplasm and the other hemoglobin genes were found in the mitochondria. The expression of hbaa1, hbaa2, hbba1 and hbba2 genes in liver, gill and blood showed an up-regulated trend after 12h of acute hypoxia stress, though the difference was not significant (P<0.05). The expression levels of hbaa1, hbba1, hbaa2, and hbba2 genes in liver and blood reached the peak at 24 to 96h under chronic hypoxia (P<0.05). In gill tissue, the highest expression of hbaa1, hbaa2, and hbba1 appeared at 196h after chronic hypoxia, while hbba2 reached its peak at 24h. This study reveals the role of the hemoglobin gene family in hypoxic environment of T. pappenheimi, accumulating valuable scientific data for its conservation.

     

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