The molecular basis for adaptations to extreme environments can now be understood by interrogating the ever-increasing number of sequenced genomes. Mammals such as cetaceans, bats, and highland species can protect themselves from oxidative stress, a disruption in the balance of reactive oxygen species, which results in oxidative injury and cell damage. Here, we consider the evolution of the glutathione peroxidase (GPX) family of antioxidant enzymes by interrogating publicly available genome data from 70 mammalian species from all major clades. We identified 8 GPX subclasses ubiquitous to all mammalian groups. Mammalian GPX gene families resolved into the GPX4/7/8 and GPX1/2/3/5/6 groups and are characterized by several instances of gene duplication and loss, indicating a dynamic process of gene birth and death in mammals. Seven of the eight GPX subfamilies (all but GPX7) were under positive selection, with the residues under selection located at or close to active sites or at the dimer interface. We also reveal evidence of a correlation between ecological niches (e.g. high oxidative stress) and the divergent selection and gene copy number of GPX subclasses. Notably, a convergent expansion of GPX1 was observed in several independent lineages of mammals under oxidative stress and may be important for avoiding oxidative damage. Collectively, this study suggests that the GPX gene family has shaped the adaption of mammals to stressful environments.

中文翻译：

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氧化应激驱动哺乳动物谷胱甘肽过氧化物酶 (GPX) 基因家族的不同进化

现在可以通过询问不断增加的测序基因组数量来理解适应极端环境的分子基础。鲸类、蝙蝠和高原物种等哺乳动物可以保护自己免受氧化应激，即破坏活性氧平衡，从而导致氧化损伤和细胞损伤。在这里，我们通过询问来自所有主要进化枝的 70 个哺乳动物物种的公开可用的基因组数据来考虑抗氧化酶的谷胱甘肽过氧化物酶 (GPX) 家族的进化。我们确定了所有哺乳动物群体普遍存在的 8 个 GPX 亚类。哺乳动物 GPX 基因家族分解为 GPX4/7/8 和 GPX1/2/3/5/6 组，并以几个基因复制和丢失实例为特征，表明哺乳动物基因出生和死亡的动态过程。八个 GPX 亚家族中的七个（除 GPX7 外）均处于正选择状态，选择的残基位于或靠近活性位点或二聚体界面。我们还揭示了生态位（例如高氧化应激）与 GPX 亚类的不同选择和基因拷贝数之间相关性的证据。值得注意的是，在氧化应激下的几个独立哺乳动物谱系中观察到 GPX1 的收敛扩展，这对于避免氧化损伤可能很重要。总的来说，这项研究表明 GPX 基因家族塑造了哺乳动物对压力环境的适应。高氧化应激）和GPX亚类的不同选择和基因拷贝数。值得注意的是，在氧化应激下的几个独立哺乳动物谱系中观察到 GPX1 的收敛扩展，这对于避免氧化损伤可能很重要。总的来说，这项研究表明 GPX 基因家族塑造了哺乳动物对压力环境的适应。高氧化应激）和GPX亚类的不同选择和基因拷贝数。值得注意的是，在氧化应激下的几个独立哺乳动物谱系中观察到 GPX1 的收敛扩展，这对于避免氧化损伤可能很重要。总的来说，这项研究表明 GPX 基因家族塑造了哺乳动物对压力环境的适应。