Arabie Daniel A, Moncrief Olivia G, Shirmer Samantha M, Hand Steven C
Division of Cellular Developmental and Integrative Biology, Louisiana State University, Baton Rouge, LA, 70803, USA.
Division of Biochemistry and Molecular Biology, Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA.
J Comp Physiol B. 2025 Aug 26. doi: 10.1007/s00360-025-01631-2.
Deep metabolic transitions promoted by anoxia and diapause are tolerated for years by embryos of the brine shrimp, Artemia franciscana, whereas even short metabolic disruptions in mammals are accompanied by bursts of reactive oxygen species (ROS) that cause tissue damage during ischemia-reperfusion. We hypothesized mitochondria from these embryos are mechanistically poised to avoid ROS bursts and the associated oxidative stress during metabolic recovery. Isolated mitochondria that exhibited robust functional coupling were exposed to anoxia-reoxygenation (A/R) or continuous normoxia. HO efflux was statistically identical between A/R versus normoxia groups (p = 0.221). Addition of auranofin and dinitrochlorobenzene, inhibitors of ROS scavenging pathways, promoted a five-fold increase in HO release for the normoxic mitochondria, which confirmed that scavenging mechanisms substantially suppress routine ROS efflux. Yet when these same inhibitors were added to the A/R group, maximum HO efflux was no greater than for normoxia. Treatment with rotenone, an inhibitor of Complex I and reverse electron transport (RET), produced only a modest decrease in HO efflux. This result indicates that RET, a major contributor to ROS bursts in mammalian mitochondria, is not stimulated by A/R in A. franciscana. Lack of aconitase inactivation, protein carbonyl accumulation, and lipid hydroperoxide production demonstrate that bouts of A/R do not cause significant oxidative damage in A. franciscana mitochondria. Finally, the capacity to downregulate Complex I activity through active-deactive conformations was tested and is not operative. These data collectively suggest that Complex I from A. franciscana may not possess the capacity for RET and the associated ROS surge.
卤虫（Artemia franciscana）胚胎能够耐受由缺氧和滞育引发的深度代谢转变数年之久，而哺乳动物即使是短暂的代谢紊乱也会伴随着活性氧（ROS）的爆发，这会在缺血再灌注期间导致组织损伤。我们推测这些胚胎的线粒体在机制上能够避免代谢恢复过程中ROS的爆发以及相关的氧化应激。将表现出强大功能偶联的分离线粒体暴露于缺氧复氧（A/R）或持续常氧环境中。A/R组与常氧组之间的HO外流在统计学上无显著差异（p = 0.221）。添加金诺芬和二硝基氯苯（ROS清除途径抑制剂）可使常氧线粒体的HO释放增加五倍，这证实了清除机制可大幅抑制常规ROS外流。然而，当将这些相同的抑制剂添加到A/R组时，最大HO外流并不比常氧组更大。用鱼藤酮（复合体I和逆向电子传递（RET）的抑制剂）处理仅使HO外流适度降低。这一结果表明，RET是哺乳动物线粒体中ROS爆发的主要促成因素，但在卤虫中不会因A/R而被激活。缺乏乌头酸酶失活、蛋白质羰基积累和脂质氢过氧化物产生表明，A/R发作不会对卤虫线粒体造成显著的氧化损伤。最后，测试了通过活性-失活构象下调复合体I活性的能力，结果显示该能力不起作用。这些数据共同表明，卤虫的复合体I可能不具备RET及相关ROS激增的能力。
