Do mitochondrial properties explain intraspecific variation in thermal tolerance?
Do mitochondrial properties explain intraspecific variation in thermal tolerance?
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DOI：
10.1242/jeb.024034
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发表时间：
2009-02-15
影响因子：
2.8
通讯作者：
Schulte, Patricia M.
中科院分区：
文献类型：
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作者：
Fangue, Nann A.;Richards, Jeffrey G.;Schulte, Patricia M.
随着全球气温的上升，人们越来越需要了解决定生物热生态位的生理机制。在这里，我们使用两个不同热生态位的鳉鱼亚种（Fundulus heteroclitus）来验证线粒体能力随着冷驯化和适应的增加与热耐受性的降低有关的假设。我们评估了适应不同温度的鳉鱼的整体代谢率、线粒体数量和线粒体功能。北方亚种的线粒体酶活性和mRNA水平更高，特别是在冷适应的鱼类中，这表明推定的冷适应北方亚种在应对冷驯化时具有更大的线粒体数量增加能力。当在鱼的驯化温度下测试时，寒冷驯化的北方鱼的最大adp刺激（状态III）线粒体体外耗氧率高于南方鱼，但在较高的驯化温度下，亚种之间没有差异。在所有驯化温度下，北方亚种鱼的整体代谢率都较高。冷驯化也改变了线粒体呼吸对急性温度挑战的反应。在低测试温度下，适应寒冷的北方鱼类的线粒体耗氧量高于南方鱼类，但在高测试温度下则相反。这些差异反映在整个生物体的耗氧量上。我们的数据表明，在不同的鳉鱼亚种之间，线粒体功能和数量的可塑性是不同的，较不耐高温的北方亚种在寒冷中有更大的能力增加线粒体容量。然而，在温暖的驯化温度下，亚种之间的线粒体特性几乎没有差异，尽管在这些温度下整个生物体的耗氧量和热耐受性都存在差异。
As global temperatures rise, there is a growing need to understand the physiological mechanisms that determine an organism's thermal niche. Here, we test the hypothesis that increases in mitochondrial capacity with cold acclimation and adaptation are associated with decreases in thermal tolerance using two subspecies of killifish (Fundulus heteroclitus) that differ in thermal niche. We assessed whole-organism metabolic rate, mitochondrial amount and mitochondrial function in killifish acclimated to several temperatures. Mitochondrial enzyme activities and mRNA levels were greater in fish from the northern subspecies, particularly in cold-acclimated fish, suggesting that the putatively cold-adapted northern subspecies has a greater capacity for increases in mitochondrial amount in response to cold acclimation. When tested at the fish's acclimation temperature, maximum ADP-stimulated (State III) rates of mitochondrial oxygen consumption in vitro were greater in cold-acclimated northern fish than in southern fish but did not differ between subspecies at higher acclimation temperatures. Whole-organism metabolic rate was greater in fish of the northern subspecies at all acclimation temperatures. Cold acclimation also changed the response of mitochondrial respiration to acute temperature challenge. Mitochondrial oxygen consumption was greater in cold-acclimated northern fish than in southern fish at low test temperatures, but the opposite was true at high test temperatures. These differences were reflected in whole-organism oxygen consumption. Our data indicate that the plasticity of mitochondrial function and amount differs between killifish subspecies, with the less high-temperature tolerant, and putatively cold adapted, northern subspecies having greater ability to increase mitochondrial capacity in the cold. However, there were few differences in mitochondrial properties between subspecies at warm acclimation temperatures, despite differences in both whole-organism oxygen consumption and thermal tolerance at these temperatures.