Sun Hong, Ye Kaihong, Liu Denghui, Pan Dan, Gu Shiming, Wang Zhenlong
School of Physical Education (Main campus), Zhengzhou University, Zhengzhou 450000, China.
School of Life Sciences, Zhengzhou University, Zhengzhou 450000, China.
Biology (Basel). 2020 May 20;9(5):106. doi: 10.3390/biology9050106.
The Mandarin vole (), a typical subterranean rodent, has undergone hematological adaptations to tolerate the hypoxic/hypercapnic underground environment. Hemoglobin (Hb) genes encode respiratory proteins functioning principally in oxygen binding and transport to various tissues and organs. To investigate the evolution of α- and β-hemoglobin (Hb) in subterranean rodent species, we sequenced Hb genes of the Mandarin vole and the related aboveground Brandt's vole (. ). Sequencing showed that in both voles, α-globin was encoded by a cluster of five functional genes in the following linkage order: , , , , and ; among these, is a pseudogene in both voles. The β-globin gene cluster in both voles also included five functional genes in the following linkage order: , , , , and . Phylogenetic analysis revealed that the Mandarin vole underwent convergent evolution with its related aboveground species (Brandt's vole) but not with other subterranean rodent species. Selection pressure analyses revealed that α- and β-globin genes are under strong purifying selection (ω < 1), and branch-site analyses identified positive selection sites on and in different subterranean rodent species. This suggests that the adaptive evolution of these genes enhanced the ability of Hb to store and transport oxygen in subterranean rodent species. Our findings highlight the critical roles of Hb genes in the evolution of hypoxia tolerance in subterranean rodent species.
棕色田鼠是一种典型的地下啮齿动物，它在血液学方面进行了适应性变化，以耐受低氧/高碳酸的地下环境。血红蛋白（Hb）基因编码主要在氧气结合以及向各种组织和器官运输氧气过程中发挥作用的呼吸蛋白。为了研究地下啮齿动物物种中α-和β-血红蛋白（Hb）的进化情况，我们对棕色田鼠以及相关的地上种类布氏田鼠的Hb基因进行了测序。测序结果表明，在这两种田鼠中，α-珠蛋白由五个功能基因组成的基因簇编码，其连锁顺序如下：、、、、，其中，在两种田鼠中均为假基因。两种田鼠的β-珠蛋白基因簇也包括五个功能基因，连锁顺序如下：、、、、。系统发育分析表明，棕色田鼠与其相关的地上物种（布氏田鼠）经历了趋同进化，但与其他地下啮齿动物物种没有趋同进化。选择压力分析表明，α-和β-珠蛋白基因受到强烈的纯化选择（ω < 1），分支位点分析确定了不同地下啮齿动物物种中、上的正选择位点。这表明这些基因的适应性进化增强了Hb在地下啮齿动物物种中储存和运输氧气的能力。我们的研究结果突出了Hb基因在地下啮齿动物物种耐缺氧进化中的关键作用。
