Data for Interindividual variation in maximum aerobic metabolism varies with gill morphology and myocardial bioenergetics in Gulf killifish

This study asked whether interindividual variation in maximum and standard
aerobic metabolic rates of the Gulf killifish, Fundulus grandis, correlate
with gill morphology and cardiac mitochondrial bioenergetics, traits
reflecting critical steps in the O2 transport cascade from the environment
to the tissues. Maximum metabolic rate (MMR) was positively related to
body mass, total gill filament length, and myocardial oxygen consumption
during maximum oxidative phosphorylation (multiple R2 = 0.836).
Standard metabolic rate (SMR) was positively related to body mass, total
gill filament length, and myocardial oxygen consumption during maximum
electron transport system activity (multiple R2 = 0.717). After
controlling for body mass, individuals with longer gill filaments, summed
over all gill arches, or greater cardiac respiratory capacity had higher
whole-animal metabolic rates. The overall model fit and the explanatory
power of individual predictor variables were better for MMR than for SMR,
suggesting that gill morphology and myocardial bioenergetics are more
important in determining maximum rather than resting metabolism. After
controlling for body mass, heart ventricle mass was not related to
variation in MMR or SMR, indicating that the quality of the heart (i.e.,
the capacity for mitochondrial metabolism) was more influential than heart
size. Finally, myocardial oxygen consumption required to offset the
dissipation of the transmembrane proton gradient in the absence of ATP
synthesis was not correlated with either MMR or SMR. The results support
the idea that interindividual variation in aerobic metabolism,
particularly MMR, is associated with variation in specific steps in the O2
transport cascade.

本研究旨在探讨墨西哥湾底鳉（Fundulus grandis）的最大有氧代谢率与标准有氧代谢率的个体间差异，是否与鳃形态及心脏线粒体生物能学（mitochondrial bioenergetics）特征相关——此类特征反映了从环境到组织的氧气转运级联反应中的关键环节。最大代谢率（Maximum Metabolic Rate, MMR）与体质量、鳃丝总长度以及最大氧化磷酸化（oxidative phosphorylation）过程中的心肌耗氧量呈显著正相关（多重决定系数R²=0.836）；标准代谢率（Standard Metabolic Rate, SMR）则与体质量、鳃丝总长度以及最大电子传递系统（electron transport system）活性下的心肌耗氧量呈显著正相关（多重决定系数R²=0.717）。在控制体质量变量后，鳃弓总鳃丝更长或心脏呼吸容量更高的个体，其整体动物代谢水平更高。相较于SMR，MMR的整体模型拟合优度与单个预测变量的解释力均更优异，提示鳃形态与心肌生物能学特征对最大代谢率的调控作用强于静息代谢率。在控制体质量后，心室质量与MMR或SMR的个体差异均无显著关联，表明心脏功能质量（即线粒体代谢能力）较心脏体积更具影响力。此外，在无ATP合成（ATP synthesis）的条件下，抵消跨膜质子梯度（transmembrane proton gradient）耗散所需的心肌耗氧量，与MMR或SMR均无相关性。本研究结果支持如下学术观点：有氧代谢的个体间差异（尤其是MMR），与氧气转运级联反应中特定步骤的变异存在显著关联。