Data from: Links between mitochondrial function, whole-animal metabolic rate, telomere dynamics and swimming performance in minnows

The majority of fish swim by aerobic muscular force, and so there has been considerable interest in the metabolic basis for swimming. Most of this work has measured whole-body oxygen consumption as a metabolic proxy, without any quantification of the actual energy that is produced at the cellular level. In this study we explored links between organism level metabolic rate (both standard (SMR) and maximal (MMR)), mitochondrial function - the rates of oxygen consumption associated with oxidative phosphorylation (OXPHOS) and offsetting proton leak (i.e., OXPHOS coupling efficiency; OxCE) - and swim performance (Ucrit), using the European minnow (Phoxinus phoxinus). We also measured the relative proportion of aerobic (slow twitch) and anaerobic (fast twitch) muscle fibres within the muscle tissue. Lastly, we measured mitochondrial reactive oxygen species (ROS) production rates and also the telomere lengths of the minnows (since rates of telomere shortening are known to be influenced by ROS). We found that the critical swimming speed of a fish was unrelated to measures of mitochondrial efficiency (OxCE), MMR or to the proportion of aerobic fibres within the muscle mass. However, Ucrit was positively related to an individual's SMR and its OXPHOS capacity, indicating that better swimmers are supported by a higher baseline metabolism and a greater cellular capacity for producing ATP. There was also a significant link between OxCE and rates of mitochondrial ROS production, but this was unrelated to telomere length. This study exemplifies how cellular energy production can influence overall performance.

绝大多数鱼类依靠有氧肌肉力量完成游动，因此学界对于鱼类游泳行为的代谢基础始终抱有浓厚研究兴趣。既往相关研究多以全身体耗氧量作为代谢替代指标，但未对细胞水平实际产生的能量进行量化。本研究以欧洲鲦鱼（*Phoxinus phoxinus*）为实验对象，探究了个体水平代谢率[包括标准代谢率（Standard Metabolic Rate, SMR）与最大代谢率（Maximal Metabolic Rate, MMR）]、线粒体功能——即与氧化磷酸化（Oxidative Phosphorylation, OXPHOS）及代偿性质子漏相关的氧消耗速率，亦即氧化磷酸化偶联效率（OxCE）——与游泳性能（临界游泳速度Ucrit）之间的关联。此外，本研究还测定了肌肉组织内有氧（慢肌）与无氧（快肌）肌纤维的相对占比。最后，我们测定了实验鱼的线粒体活性氧（Reactive Oxygen Species, ROS）生成速率及其端粒长度——已知端粒缩短速率会受到ROS的影响。研究结果显示，鱼类的临界游泳速度与线粒体效率（OxCE）、最大代谢率（MMR）以及肌肉中有氧纤维的占比均无显著关联。然而，临界游泳速度与个体的标准代谢率及其氧化磷酸化容量呈显著正相关，这表明游动能力更强的个体拥有更高的基础代谢水平与更强的细胞ATP生成能力。此外，氧化磷酸化偶联效率与线粒体活性氧生成速率之间存在显著关联，但这一关联与端粒长度无关。本研究清晰展现了细胞能量产生过程如何影响机体整体运动性能。