耐热潮间带三鳍鱼（雷公藤科）在急性热应激下比潮下带物种更能维持 ATP 动力学

Thermally tolerant intertidal triplefin fish (Tripterygiidae) sustain ATP dynamics better than subtidal species under acute heat stress.

Keywords：Physiology, Metabolism, Ecology, Ecophysiology 

关键词：生理学、新陈代谢、生态学、生态生理学 • 生化细胞

非哺乳动物：鱼
作者：Willis Jaime R, Hickey Anthony J R, Devaux Jules B L

出版期刊：《Scientifc Reports》（2021年）

Abstract：

Temperature is a key factor that affects all levels of organization. Minute shifts away from thermal optima result in detrimental effects that impact growth, reproduction and survival. Metabolic rates of ectotherms are especially sensitive to temperature and for organisms exposed to high acute temperature changes, in particular intertidal species, energetic processes are often negatively impacted. Previous investigations exploring acute heat stress have implicated cardiac mitochondrial function in determining thermal tolerance. The brain, however, is by weight, one of the most metabolically active and arguably the most temperature sensitive organ. It is essentially aerobic and entirely reliant on oxidative phosphorylation to meet energetic demands, and as temperatures rise, mitochondria become less efficient at synthesising the amount of ATP required to meet the increasing demands. This leads to an energetic crisis. Here we used brain homogenate of three closely related triplefin fish species (Bellapiscis medius, Forsterygion lapillum, and Forsterygion varium) and measured respiration and ATP dynamics at three temperatures (15, 25 and 30 °C). We found that the intertidal B. medius and F. lapillum were able to maintain rates of ATP production above rates of ATP hydrolysis at high temperatures, compared to the subtidal F. varium, which showed no difference in rates at 30 °C. These results showed that brain mitochondria became less efficient at temperatures below their respective species thermal limits, and that energetic surplus of ATP synthesis over hydrolysis narrows. In subtidal species synthesis matches hydrolysis, leaving no scope to elevate ATP supply.

文章摘要：

温度是影响组织各个层面的关键因素。偏离热最佳状态的微小变化会导致影响生长、繁殖和生存的不利影响。变温动物的代谢率对温度特别敏感，对于暴露于高急性温度变化的生物，特别是潮间带物种，能量过程经常受到负面影响。先前探索急性热应激的研究表明心脏线粒体功能在确定热耐受性方面的作用。然而，按重量计算，大脑是新陈代谢最活跃的器官之一，可以说是对温度最敏感的器官。它本质上是有氧的，完全依赖氧化磷酸化来满足能量需求，随着温度的升高，线粒体在合成满足不断增长的需求所需的 ATP 量方面的效率降低。这导致了能量危机。在这里，我们使用了三种密切相关的三鳍鱼类（Bellapiscis medius、Forsterygion lapillum 和 Forsterygion varium）的脑匀浆，并在三种温度（15、25 和 30°C）下测量了呼吸和 ATP 动力学。我们发现，与潮下带的 F. varium 相比，潮间带的 B. medius 和 F. lapillum 能够将 ATP 的产生速率保持在高于 ATP 水解的速率，后者在 30 °C 下的速率没有差异。这些结果表明，脑线粒体在低于其各自物种的热极限的温度下效率降低，并且 ATP 合成相对于水解的能量过剩变窄。在潮下带物种的合成与水解相匹配，没有提高 ATP 供应的空间。

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