The ability of Antarctic notothenioid fishes to mount a robust molecular response to hypoxia is largely unknown. The transcription factor, hypoxia-inducible factor-1 (HIF-1), a heterodimer of HIF-1α and HIF-1β subunits, is the master regulator of oxygen homeostasis in most metazoans. We sought to determine if, in the hearts of Antarctic notothenioids, HIF-1 is activated and functional in response to either an acute heat stress or hypoxia. The red-blooded Notothenia coriiceps and the hemoglobinless icefish, Chaenocephalus aceratus, were exposed to their critical thermal maximum (CT_MAX) or hypoxia (5.0 ± 0.3 mg of O₂ L⁻¹) for 2 h. Additionally, N. coriiceps was exposed to 2.3 ± 0.3 mg of O₂ L⁻¹ for 12 h, and red-blooded Gobionotothen gibberifrons was exposed to both levels of hypoxia. Levels of HIF-1α were quantified in nuclei isolated from heart ventricles using western blotting. Transcript levels of genes involved in anaerobic metabolism, and known to be regulated by HIF-1, were quantified by real-time PCR, and lactate levels were measured in heart ventricles. Protein levels of HIF-1α increase in nuclei of hearts of N. coriiceps and C. aceratus in response to exposure to CT_MAX and in hearts of N. coriiceps exposed to severe hypoxia, yet mRNA levels of anaerobic metabolic genes do not increase in any species, nor do lactate levels increase, suggesting that HIF-1 does not stimulate metabolic remodeling in hearts of notothenioids under these conditions. Together, these data suggest that Antarctic notothenioids may be vulnerable to hypoxic events, which are likely to increase with climate warming.

南极拟南芥鱼对缺氧产生强烈的分子反应的能力在很大程度上是未知的。转录因子缺氧诱导因子-1 (HIF-1) 是 HIF-1α 和 HIF-1β 亚基的异二聚体，是大多数后生动物氧稳态的主要调节因子。我们试图确定，在南极拟南芥的心脏中，HIF-1 是否在响应急性热应激或缺氧时被激活和起作用。红血的Notothenia coriiceps和无血红蛋白的冰鱼Chaenocephalus aceratus暴露于它们的临界热最大值 (CT _MAX ) 或缺氧 (5.0 ± 0.3 mg O ₂ L ^-1 ) 2 小时。此外，N. coriiceps暴露于 2.3 ± 0.3 mg O ₂ L ^-1 12 小时，并且红血Gobionotthen gibberifrons暴露于两种缺氧水平。使用蛋白质印迹法在从心室分离的细胞核中量化 HIF-1α 的水平。参与厌氧代谢并已知受 HIF-1 调节的基因的转录水平通过实时 PCR 进行量化，并在心室中测量乳酸水平。的HIF-1α增加的心脏的核蛋白质水平N. coriiceps和C. aceratus响应于暴露于CT _MAX和在心中N. coriiceps暴露于严重缺氧，但厌氧代谢基因的 mRNA 水平在任何物种中都没有增加，乳酸水平也没有增加，这表明 HIF-1 在这些条件下不会刺激类拟杆菌的心脏代谢重塑。总之，这些数据表明南极拟南芥可能容易受到缺氧事件的影响，而缺氧事件可能会随着气候变暖而增加。