Abstract：
The Siberian frog Rana amurensis has a uniquely high tolerance to hypoxia among amphibians, as it is able to withstand several months underwater with almost no oxygen (0.2 mg/liter) vs. several days for other studied species. Since it was hypothesized that hypoxia actives the antioxidant defense system in hypoxia-tolerant animals, one would expect similar response in R. amurensis. Here, we studied the effect of hypoxia in the Siberian frog based on the transcriptomic data, activities of antioxidant enzyme, and content of low-molecular-weight antioxidants. Exposure to hypoxia upregulated expression of three relevant transcripts (catalase in the brain and two aldo-keto reductases in the liver). The activities of peroxidase in the blood and catalase in the liver were significantly increased, while the activity of glutathione S-transferase in the liver was reduced. The content of low-molecular-weight antioxidants (thiols and ascorbate) in the heart and liver was unaffected. In general, only a few components of the antioxidant defense system were affected by hypoxia, while most remained unchanged. Comparison to other hypoxia-tolerant species suggests species-specific adaptations to hypoxia-related ROS stress.
摘要：
西伯利亚蛙Ranaamurensis在两栖动物中对缺氧具有独特的高耐受性，因为它能够承受几个月的水下几乎没有氧气（0.2毫克/升）与其他研究物种的几天。由于假设缺氧激活了耐缺氧动物的抗氧化防御系统，人们会期望在R.amurensis中产生类似的反应。这里,我们根据转录组数据研究了缺氧对西伯利亚蛙的影响，抗氧化酶的活性，和低分子量抗氧化剂的含量。暴露于缺氧会上调三种相关转录物（大脑中的过氧化氢酶和肝脏中的两种醛酮还原酶）的表达。血液中的过氧化物酶和肝脏中的过氧化氢酶的活性显著增加，而肝脏中谷胱甘肽S-转移酶的活性降低。心脏和肝脏中低分子量抗氧化剂（硫醇和抗坏血酸盐）的含量不受影响。总的来说,抗氧化防御系统中只有少数成分受到缺氧的影响,而大多数保持不变。与其他耐缺氧物种的比较表明，物种特异性适应缺氧相关的ROS胁迫。
