Marine Science Institute, The University of Texas at Austin, Port Aransas, TX 78373, USA.
Department of Zoology, The University of British Columbia, Vancouver, BC, CanadaV6T 1Z4.
J Exp Biol. 2024 Aug 15;227(16). doi: 10.1242/jeb.247618. Epub 2024 Aug 30.
Respiratory plasticity is a beneficial response to chronic hypoxia in fish. Red drum, a teleost that commonly experiences hypoxia in the Gulf of Mexico, have shown respiratory plasticity following sublethal hypoxia exposure as juveniles, but implications of hypoxia exposure during development are unknown. We exposed red drum embryos to hypoxia (40% air saturation) or normoxia (100% air saturation) for 3 days post fertilization (dpf). This time frame encompasses hatch and exogenous feeding. At 3 dpf, there was no difference in survival or changes in size. After the 3-day hypoxia exposure, all larvae were moved and reared in common normoxic conditions. Fish were reared for ∼3 months and effects of the developmental hypoxia exposure on swim performance and whole-animal aerobic metabolism were measured. We used a cross design wherein fish from normoxia (N=24) were exercised in swim tunnels in both hypoxia (40%, n=12) and normoxia (100%, n=12) conditions, and likewise for hypoxia-exposed fish (n=10 in each group). Oxygen consumption, critical swim speed (Ucrit), critical oxygen threshold (Pcrit) and mitochondrial respiration were measured. Hypoxia-exposed fish had higher aerobic scope, maximum metabolic rate, and higher liver mitochondrial efficiency relative to control fish in normoxia. Interestingly, hypoxia-exposed fish showed increased hypoxia sensitivity (higher Pcrit) and recruited burst swimming at lower swim speeds relative to control fish. These data provide evidence that early hypoxia exposure leads to a complex response in later life.
呼吸可塑性是鱼类对慢性低氧的有益反应。红鼓鱼是一种在墨西哥湾经常经历低氧的硬骨鱼，在亚致死低氧暴露后表现出呼吸可塑性，但在发育过程中低氧暴露的影响尚不清楚。我们将红鼓鱼胚胎暴露于低氧（40%空气饱和度）或常氧（100%空气饱和度）中 3 天受精后（dpf）。这个时间框架包括孵化和外源性喂养。在 3 天pf 时，存活率或大小变化没有差异。在 3 天低氧暴露后，所有幼虫都被转移并在常氧条件下饲养。鱼类饲养了约 3 个月，并测量了发育性低氧暴露对游泳性能和整体动物有氧代谢的影响。我们使用交叉设计，其中来自常氧（N=24）的鱼在游泳隧道中在低氧（40%，n=12）和常氧（100%，n=12）条件下进行运动，而低氧暴露的鱼（n=10 在每组）。测量耗氧量、临界游泳速度（Ucrit）、临界氧阈值（Pcrit）和线粒体呼吸。与常氧中的对照鱼相比，低氧暴露的鱼具有更高的有氧范围、最大代谢率和更高的肝脏线粒体效率。有趣的是，与对照鱼相比，低氧暴露的鱼在较低的游泳速度下表现出更高的缺氧敏感性（更高的 Pcrit）和爆发性游泳。这些数据提供了证据，表明早期低氧暴露会导致后期生活中的复杂反应。
