Negrete Benjamin, Ackerly Kerri Lynn, Dichiera Angelina M, Esbaugh Andrew J
Marine Science Institute, The University of Texas at Austin, Port Aransas, TX 78373, USA.
Marine Science Institute, The University of Texas at Austin, Port Aransas, TX 78373, USA.
Sci Total Environ. 2022 Nov 25;849:157880. doi: 10.1016/j.scitotenv.2022.157880. Epub 2022 Aug 6.
Ocean deoxygenation is a pressing concern in the face of climate change. In response to prolonged hypoxia, fishes have demonstrated the ability to dynamically regulate hemoglobin (Hb) expression to enhance oxygen (O) uptake. Here, we examined hypoxia-inducible Hb expression in red drum (Sciaenops ocellatus) and the subsequent implications on Hb-O binding affinity and aerobic scope. Fish were acclimated to 30 % air saturation for 1 d, 4 d, 8 d, 2 w, or 6 w, and red blood cells were collected for gene expression and biochemical profiling. Hypoxia acclimation induced significant up-regulation of one Hb subunit isoform (hbα 2) relative to control by 4 d with consistent upregulation thereafter. Hematocrit increased in hypoxia, with no changes in the allosteric modulator [NTP] at any time point. Changes in Hb expression co-occurred with a reduced Root effect (~26 % in normoxia, ~14 % in hypoxia) at a physiologically relevant pH while increasing O binding affinity (i.e., lower P). These changes correlated with increased maximum metabolic rate and aerobic scope relative to controls when fish were tested in hypoxia. These results demonstrate an important role for Hb multiplicity in improving O affinity and maximizing respiratory performance in hypoxia.
面对气候变化，海洋脱氧是一个紧迫的问题。为应对长期缺氧，鱼类已表现出动态调节血红蛋白（Hb）表达以增强氧气（O）摄取的能力。在此，我们研究了红鼓鱼（Sciaenops ocellatus）中缺氧诱导的Hb表达及其对Hb-O结合亲和力和有氧代谢范围的后续影响。将鱼分别适应于30%空气饱和度1天、4天、8天、2周或6周，然后收集红细胞用于基因表达和生化分析。缺氧适应在4天时相对于对照组显著上调了一种Hb亚基异构体（hbα 2）的表达，此后持续上调。缺氧时血细胞比容增加，在任何时间点变构调节剂[NTP]均无变化。在生理相关pH值下，Hb表达的变化与Root效应降低（常氧时约26%，缺氧时约14%）同时发生，同时增加了O结合亲和力（即较低的P）。当在缺氧条件下对鱼进行测试时，这些变化与相对于对照组增加的最大代谢率和有氧代谢范围相关。这些结果表明Hb多样性在改善缺氧时的O亲和力和最大化呼吸性能方面具有重要作用。
