硬骨鱼类血红蛋白转换表达的新模式——以黄河裸裂尻鱼胚胎型血红蛋白研究为例

A NEW PATTERN OF HEMOGLOBIN SWITCHING IN TELEOST FISH-STUDY OF THE EMBRYONIC HEMOGLOBIN IN THE SCHIZOPYGOPSIS PYLZOVI

  • 摘要: 为了探讨高原硬骨鱼类胚胎型血红蛋白的转换表达模式, 研究利用转录组数据和克隆方法研究了黄河裸裂尻鱼(Schizopygopsis pylzovi)胚胎型血红蛋白的组成和基因结构, 并通过qRT-PCR和整胚原位杂交方法确定了胚胎发育过程中血红蛋白基因的表达情况。结果表明, 黄河裸裂尻鱼胚胎型血红蛋白基因由hbae1、hbae4、hbbe1和hbbe3组成, 均包含3个外显子和2个内含子, 其中hbbe1/hbae1以“头对头”(3′-5′—5′-3′)转录方式串联在一起, hbbe3/hbae4则以“尾对尾”(5′-3′—3-5′)的转录方式串联在一起。进一步的研究初步判断hbae3、hbae5和hbbe2基因在裂腹鱼亚科鱼类进化过程中可能发生了丢失。qRT-PCR和整胚原位杂交结果均表明在早期胚胎发育过程中4个胚胎型血红蛋白基因的表达都是从受精后第5天(120 hpf)开始明显上升, 但是hbae4和hbbe3基因的高表达只维持在受精后第5天(120 hpf)至破膜期(216 hpf), 随后急剧下降, 而hbae1和hbbe1基因表达从破膜(216 hpf)开始急剧上升。研究揭示了硬骨鱼类一种全新的血红蛋白转换表达模式, 这可能与黄河裸裂尻鱼特殊的进化历程和高原环境的适应有关, 研究结果将为进一步深入研究硬鱼类血红蛋白的时序转换表达和环境适应机制奠定基础。

     

    Abstract: In order to investigate the pattern of hemoglobin switching in teleost fish endemic to Qinghai-Tibetan Plateau, the membership composition and gene structure of embryonic hemoglobin were determined using transcriptome data and cloning in S. pylzovi. Then qRT-PCR and whole embryo in situ hybridization were used to detect the expression patterns of hemoglobin genes during embryonic development. The results showed that the embryonic hemoglobin genes of S. pylzovi included hbae1, hbae4, hbbe1, and hbbe3, which all contain 3 exons and 2 introns, and the hbbe1/hbae1 pair was transcribed in a “head-to-head” (3′-5′—5′-3′) fashion, and hbbe3/hbae4 were arranged in a “tail-to-tail” (5′-3′—3′-5′) fashion. Further analysis indicated that the gene loss event has caused the lack of hbae3, hbae5 and hbbe2 genes in schizothoracine fish. The results of qRT-PCR and whole embryo in situ hybridization showed that the expression levels of four embryonic hemoglobin genes increased from the 5th day after fertilization (120 hpf) during the early embryo development stages. However, high expression levels of the hbae4 and hbbe3 genes were found only from the 5th day after fertilization to the hatching stage (216 hpf), and then dropped sharply, and the expression of hbae1 and hbbe1 genes increased from the beginning of hatching stage. This study observed a new pattern of hemoglobin switching in teleost fish, which may be related to the particular evolutionary history and the adaptation of the S. pylzovi to the plateau environment. This findings will lay the foundation for further investigation on the hemoglobin switching and environmental adaptation mechanism of teleost fish.

     

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