Chung Dillon J, Sparagna Genevieve C, Chicco Adam J, Schulte Patricia M
Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
Department of Medicine/Division of Cardiology, University of Colorado Anschutz Medical Center, Aurora, CO 80045, USA.
J Exp Biol. 2018 Apr 11;221(Pt 7):jeb174458. doi: 10.1242/jeb.174458.
The effect of temperature on mitochondrial performance is thought to be partly due to its effect on mitochondrial membranes. Numerous studies have shown that thermal acclimation and adaptation can alter the amount of inner-mitochondrial membrane (IMM), but little is known about the capacity of organisms to modulate mitochondrial membrane composition. Using northern and southern subspecies of Atlantic killifish () that are locally adapted to different environmental temperatures, we assessed whether thermal acclimation altered liver mitochondrial respiratory capacity or the composition and amount of IMM. We measured changes in phospholipid headgroups and headgroup-specific fatty acid (FA) remodeling, and used respirometry to assess mitochondrial respiratory capacity. Acclimation to 5°C and 33°C altered mitochondrial respiratory capacity in both subspecies. Northern exhibited greater mitochondrial respiratory capacity across acclimation temperatures, consistent with previously observed subspecies differences in whole-organism aerobic metabolism. Mitochondrial phospholipids were altered following thermal acclimation, and the direction of these changes was largely consistent between subspecies. These effects were primarily driven by remodeling of specific phospholipid classes and were associated with shifts in metabolic phenotypes. There were also differences in membrane composition between subspecies that were driven largely by differences in phospholipid classes. Changes in respiratory capacity between subspecies and with acclimation were largely but not completely accounted for by alterations in the amount of IMM. Taken together, these results support a role for changes in liver mitochondrial function in the ectothermic response to thermal stress during both acclimation and adaptation, and implicate lipid remodeling as a mechanism contributing to these changes.
温度对线粒体性能的影响被认为部分归因于其对线粒体膜的作用。大量研究表明，热驯化和适应能够改变线粒体内膜（IMM）的数量，但对于生物体调节线粒体膜组成的能力却知之甚少。利用在当地适应了不同环境温度的大西洋鳉鱼的北方和南方亚种，我们评估了热驯化是否会改变肝脏线粒体的呼吸能力或IMM的组成及数量。我们测量了磷脂头部基团的变化以及头部基团特异性脂肪酸（FA）重塑情况，并使用呼吸测定法评估线粒体呼吸能力。在5°C和33°C下的驯化改变了两个亚种的线粒体呼吸能力。北方亚种在整个驯化温度范围内表现出更强的线粒体呼吸能力，这与之前观察到的该亚种在全生物体有氧代谢方面的差异一致。热驯化后线粒体磷脂发生了改变，并且这些变化的方向在两个亚种之间基本一致。这些效应主要是由特定磷脂类别的重塑驱动的，并且与代谢表型的转变有关。亚种之间的膜组成也存在差异，这在很大程度上是由磷脂类别差异驱动的。亚种之间以及随着驯化而产生的呼吸能力变化在很大程度上但并非完全由IMM数量的改变所解释。综上所述，这些结果支持了肝脏线粒体功能变化在变温动物对热应激的驯化和适应过程中的反应中所起的作用，并表明脂质重塑是导致这些变化的一种机制。
