发育性缺氧对鳄龟心脏线粒体功能的长期影响

The long-term effects of developmental hypoxia on cardiac mitochondrial function in snapping turtles

Keywords：developmental plasticity; developmental programming; electron transport chain; heart; metabolism; oxygen affinity; reactive oxygen species; reptile.

关键词：发育可塑性；发展规划； 电子传输链；心脏；代谢；氧亲和力；活性氧；爬行动物

非哺乳动物：爬行动物
作者：Galli GLJ, Ruhr IM, Crossley J, Crossley DA 2nd
出版期刊：《Frontiers in Physiology》（2021）

Abstract：

Low O2 availability (hypoxia) is a common environmental stressor in aquatic, terrestrial,and subterranean environments (Bickler and Buck, 2007). Hypoxia can have severe metabolic consequences for animals, because O2 plays a pivotal role in the production of ATP and reactive oxygen species (ROS) during oxidative phosphorylation. (Mitchell, 2011)The effects of developmental hypoxia on mitochondrial function are likely to be more profound, because environmental stress during early life can permanently alter cellular physiology and morphology.Respiration and H2O2 production were measured simultaneously with an Oxygraph O2k high-resolution respirometry system (Oroboros Instruments GmbH, Innsbruck, Austria), fitted with an O2k-fluorescence LED2-module.Mitochondrial H2O2 production and respiration rate(H202/O2) were measured in juvenile snapping turtles from normoxic (N21, red squares, n = 6) and hypoxic H10, (blue circles, n = 7) incubation ,by using a
standard substrate inhibitor titration protocol (SUIT protocol).  Discussion:Developmental hypoxia reduces mitochondrial aerobic capacity and ROS production ,increases the effificiency of mitochondrial ATP production,but has no effect on mitochondrial oxygen affifinity. This finding has ecological significance, because ROS production from RET(reverse electron transport) mainly occurs when tissues are reoxygenated after a period of anoxia or ischemia (Chouchani et al., 2016). Given that turtles regularly engage in long breath-hold dives and overwinter in anoxia for several months, limiting ROS production from RET reduces the likelihood of oxidative stress when turtles resurface. Taken together, our data suggest that developmental hypoxia programs a mitochondrial phenotype in turtles that is better able to cope with oxidative stress.

文章简介：

低 O2 可用性（缺氧）是水生、陆地和地下环境中常见的环境压力源（Bickler 和 Buck，2007 年）。缺氧会对动物产生严重的代谢后果，因为在氧化磷酸化过程中，O2 在 ATP 和活性氧 (ROS) 的产生中起着关键作用 (Mitchell, 2011)。发育缺氧对线粒体功能的影响可能更为深远，因为生命早期的环境压力会永久性地改变细胞生理和形态。文章使用配备 O2k 荧光 LED2 模块的 Oxygraph O2k 高分辨率呼吸测量系统（Oroboros Instruments GmbH，Innsbruck，Austria）同时测量呼吸和 H2O2 的产生。检测材料是海龟的心室线粒体，使用SUIT体系滴定并测量常氧、缺氧及各种状态（state）情况下的H2O2产量和呼吸速率(H2O2/O2)。结论：发育性缺氧会降低线粒体有氧能力和活性氧的产生、提高线粒体 ATP 生产效率，但是对线粒体的氧亲和力没有影响。鉴于海龟经常进行长时间的屏气潜水并在缺氧状态下过冬数月，因此限制 RET（reverse electron transport反向电子传输） 产生的 ROS 会降低海龟重新浮出水面时出现氧化应激的可能性。总之，我们的数据表明，发育性缺氧在海龟中形成了一种线粒体表型，能够更好地应对氧化应激。

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