Department of Biology and Marine Biology, University of North Carolina at Wilmington, Wilmington, NC 28403, USA.
Integr Comp Biol. 2024 Oct 28;64(4):1115-1130. doi: 10.1093/icb/icae144.
Hypoxia tolerance in aquatic ectotherms involves a suite of behavioral and physiological responses at the organismal, tissue, and cellular levels. The current study evaluated two closely related killifish species (Fundulus heteroclitus, Fundulus majalis) to evaluate responses to acute moderate and acute severe hypoxia. Routine metabolic rate and loss of equilibrium were assessed, followed by analysis in skeletal muscle of markers of oxidative damage to proteins (2,4-DNPH), lipids (4-HNE), and DNA (8-OHdG), hypoxia signaling (HIF1α, HIF2α), cellular energy state (p-AMPK: AMPK), and protein degradation (Ubiquitin, LC3B, Calpain 2, Hsp70). Both species had a similar reduction in metabolic rate at low PO2. However, F. heteroclitus was the more hypoxia-tolerant species based on a lower PO2 at which there was loss of equilibrium, perhaps due in part to a lower oxygen demand at all oxygen tensions. Despite the differences in hypoxia tolerance between the species, skeletal muscle molecular markers were largely insensitive to hypoxia, and there were few differences in responses between the species. Thus, the metabolic depression observed at the whole animal level appears to limit perturbations in skeletal muscle in both species during the hypoxia treatments.
水生变温动物的耐缺氧能力涉及到一系列在机体、组织和细胞水平上的行为和生理反应。本研究评估了两种密切相关的丽鱼科鱼类（Fundulus heteroclitus，Fundulus majalis），以评估它们对急性中度和急性重度缺氧的反应。评估了常规代谢率和失去平衡，随后分析了骨骼肌中蛋白质氧化损伤的标志物（2,4-DNPH）、脂质（4-HNE）和 DNA（8-OHdG）、缺氧信号（HIF1α、HIF2α）、细胞能量状态（p-AMPK：AMPK）和蛋白降解（泛素、LC3B、钙蛋白酶 2、Hsp70）。这两个物种在低 PO2 下的代谢率都有相似的降低。然而，由于在所有氧分压下的耗氧量较低，F. heteroclitus 是更耐缺氧的物种，在失去平衡时所需的 PO2 更低。尽管这两个物种在耐缺氧能力上存在差异，但骨骼肌分子标志物对缺氧的反应大多不敏感，并且在物种之间的反应差异很小。因此，在整个动物水平上观察到的代谢抑制似乎限制了在缺氧处理期间两种物种骨骼肌中的干扰。
