Jimenez Ana Gabriela, Van Brocklyn James, Wortman Matthew, Williams Joseph B
Department of Evolution, Ecology and Organismal Biology, Ohio State University, Columbus, Ohio, United States of America.
Cancer Institute, University of Cincinnati, Cincinnati, Ohio, United States of America.
PLoS One. 2014 Jan 30;9(1):e87349. doi: 10.1371/journal.pone.0087349. eCollection 2014.
In general, tropical birds have a "slow pace of life," lower rates of whole-animal metabolism and higher survival rates, than temperate species. A fundamental challenge facing physiological ecologists is the understanding of how variation in life-history at the whole-organism level might be linked to cellular function. Because tropical birds have lower rates of whole-animal metabolism, we hypothesized that cells from tropical species would also have lower rates of cellular metabolism than cells from temperate species of similar body size and common phylogenetic history. We cultured primary dermal fibroblasts from 17 tropical and 17 temperate phylogenetically-paired species of birds in a common nutritive and thermal environment and then examined basal, uncoupled, and non-mitochondrial cellular O2 consumption (OCR), proton leak, and anaerobic glycolysis (extracellular acidification rates [ECAR]), using an XF24 Seahorse Analyzer. We found that multiple measures of metabolism in cells from tropical birds were significantly lower than their temperate counterparts. Basal and uncoupled cellular metabolism were 29% and 35% lower in cells from tropical birds, respectively, a decrease closely aligned with differences in whole-animal metabolism between tropical and temperate birds. Proton leak was significantly lower in cells from tropical birds compared with cells from temperate birds. Our results offer compelling evidence that whole-animal metabolism is linked to cellular respiration as a function of an animal's life-history evolution. These findings are consistent with the idea that natural selection has uniquely fashioned cells of long-lived tropical bird species to have lower rates of metabolism than cells from shorter-lived temperate species.
一般来说，热带鸟类具有“慢生活节奏”，与温带物种相比，其整体动物代谢率较低，存活率较高。生理生态学家面临的一个基本挑战是理解整个生物体水平上生活史的变化如何与细胞功能相关联。由于热带鸟类的整体动物代谢率较低，我们推测，与体型相似且系统发育史相同的温带鸟类的细胞相比，热带物种的细胞代谢率也会更低。我们在共同的营养和热环境中培养了来自17种热带和17种温带系统发育配对鸟类的原代表皮成纤维细胞，然后使用XF24 Seahorse分析仪检测基础、解偶联和非线粒体细胞耗氧量（OCR）、质子泄漏和无氧糖酵解（细胞外酸化率[ECAR]）。我们发现，热带鸟类细胞中多种代谢指标显著低于温带鸟类细胞。热带鸟类细胞的基础和解偶联细胞代谢分别比温带鸟类细胞低29%和35%，这一降低与热带和温带鸟类整体动物代谢的差异密切相关。与温带鸟类细胞相比，热带鸟类细胞的质子泄漏显著更低。我们的结果提供了令人信服的证据，表明整体动物代谢与细胞呼吸相关，这是动物生活史进化的一个功能。这些发现与以下观点一致，即自然选择独特地塑造了长寿热带鸟类物种的细胞，使其代谢率低于寿命较短的温带物种的细胞。
