Despite cold adaptation, Antarctic fish show lower growth than expected from the van’t Hoff’s Q10 rule. Protein synthesis is one of the main energy-consuming processes, which is downregulated under energy deficiency. Considering the effect of temperature on growth performance, we tested if temperature-dependent cellular energy allocation to protein synthesis correlates with temperature-dependent whole-animal growth and thus thermal tolerance. Cell respiration and energy expenditure for protein synthesis were determined in hepatocytes of the circumpolar-distributed Antarctic eelpout Pachycara brachycephalum after warm acclimation (0 °C vs 5 °C) and, of two notothenioids the sub-Antarctic Lepidonotothen squamifrons and the high-Antarctic icefish Chionodraco hamatus. We used intermittent-flow respirometry to analyse cellular response to acute warming from 5 to 10 °C (P. brachycephalum) and from 1 to 5 °C (L. squamifrons, C. hamatus). Warming-induced rise in respiration was similar between 0- and 5 °C-acclimated P. brachycephalum and between L. squamifrons and C. hamatus. Irrespective of acclimation, warming decreased energy expenditure for protein synthesis in P. brachycephalum, which corresponds to reduced whole-animal growth at temperatures > 5 °C. Warming doubled energy expenditure for protein synthesis in L. squamifrons but had no effect on C. hamatus indicating that L. squamifrons might benefit from warmer waters. The species-specific temperature effect on energy expenditure for protein synthesis is discussed to mirror thermal sensitivity of whole-animal growth performance, thereby paralleling the degree of cold adaptation. Clearly more data are necessary including measurements at narrower temperature steps particularly for C. hamatus and an increased species’ number per ecotype to reinforce presented link between cellular and whole-animal thermal sensitivity.

中文翻译：

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不同南极鱼类细胞代谢的热敏感性反映了生物体的温度耐受性

尽管适应寒冷，南极鱼的生长速度低于范特霍夫 Q10 规则的预期。蛋白质合成是主要的能量消耗过程之一，在能量缺乏时会被下调。考虑到温度对生长性能的影响，我们测试了蛋白质合成的温度依赖性细胞能量分配是否与温度依赖性全动物生长以及热耐受性相关。在暖驯化（0°C 与 5°C）后，在环绕极地分布的南极鳗 Pachycara brachycephalum 的肝细胞中测定了用于蛋白质合成的细胞呼吸和能量消耗，并且在两种 notothenioids 中，亚南极 Lepidonotothen squamifrons 和高南极冰鱼Chionodraco hamatus。我们使用间歇流动呼吸测量法来分析细胞对从 5 到 10 °C（短头假单胞菌）和从 1 到 5 °C（L. squamifrons, C. hamatus）的急性变暖的反应。在 0 到 5 °C 驯化的 P. brachycephalum 以及 L. squamifrons 和 C. hamatus 之间，变暖引起的呼吸增加是相似的。无论适应情况如何，变暖都会降低 P. brachycephalum 蛋白质合成的能量消耗，这对应于温度 > 5 °C 时整个动物生长的减少。变暖使 L. squamifons 蛋白质合成的能量消耗增加了一倍，但对 C. hamatus 没有影响，表明 L. squamifons 可能受益于温暖的水域。讨论了物种特异性温度对蛋白质合成能量消耗的影响，以反映整个动物生长性能的热敏感性，从而平行冷适应的程度。显然，需要更多的数据，包括在更窄的温度步长下进行测量，特别是对 C. hamatus 和每个生态型的物种数量增加，以加强细胞和全动物热敏感性之间的现有联系。