Department of Zoology, University of British Columbia, Vancouver, BC, V6T1Z4, Canada.
Sci Rep. 2017 Nov 24;7(1):16238. doi: 10.1038/s41598-017-16598-6.
Mitochondrial function has been suggested to underlie constraints on whole-organism aerobic performance and associated hypoxia and thermal tolerance limits, but most studies have focused on measures of maximum mitochondrial capacity. Here we investigated whether variation in mitochondrial oxygen kinetics could contribute to local adaptation and plasticity in response to temperature using two subspecies of the Atlantic killifish (Fundulus heteroclitus) acclimated to a range of temperatures (5, 15, and 33 °C). The southern subspecies of F. heteroclitus, which has superior thermal and hypoxia tolerances compared to the northern subspecies, exhibited lower mitochondrial O P50 (higher O affinity). Acclimation to thermal extremes (5 or 33 °C) altered mitochondrial O P50 in both subspecies consistent with the effects of thermal acclimation on whole-organism thermal tolerance limits. We also examined differences between subspecies and thermal acclimation effects on whole-blood Hb O-P50 to assess whether variation in oxygen delivery is involved in these responses. In contrast to the clear differences between subspecies in mitochondrial O-P50 there were no differences in whole-blood Hb-O P50 between subspecies. Taken together these findings support a general role for mitochondrial oxygen kinetics in differentiating whole-organism aerobic performance and thus in influencing species responses to environmental change.
线粒体功能被认为是限制整个生物体有氧表现和相关缺氧及耐热极限的基础，但大多数研究都集中在最大线粒体容量的测量上。在这里，我们研究了两种适应不同温度的大西洋小翻车鱼（Fundulus heteroclitus）亚种，其一种是南方亚种，另一种是北方亚种，以探讨线粒体氧动力学的变化是否能为适应和对温度的可塑性做出贡献。与北方亚种相比，南方亚种具有更好的耐热性和耐缺氧性，其线粒体 O P50 较低（亲和力较高）。两种亚种的线粒体 O P50 在热极端（5 或 33°C）适应中发生改变，这与热适应对整个生物体耐热极限的影响一致。我们还研究了亚种间的差异以及热适应对全血 Hb O-P50 的影响，以评估氧气输送的变化是否参与了这些反应。与亚种间线粒体 O-P50 的明显差异相反，亚种间全血 Hb-O P50 没有差异。这些发现共同支持了线粒体氧动力学在区分整个生物体有氧表现方面的一般作用，从而影响物种对环境变化的反应。
