全球变暖导致极端天气事件的频率和强度增加，在不同的日子和季节中，放大等温线所面临的温度宽度。尽管昼夜热变化的重要性和生态相关性，关于基因表达模式和生理学的绝大多数知识源于适应恒定温度或暴露于新温度状态的早期阶段的动物。如果异质热环境与恒定热环境不同地调制响应，我们预测气候变暖影响的现有能力可能会受到损害。为了解决这个知识差距，我们将加拿大肺鱼（Latescalcarifer）适应到23°C，29°C（最佳），35°C和热循环条件（每天23-35°C，平均值为29°C），并在适应前以及适应2和17周后采样肝脏和白肌肉组织。NanoStringnCounter技术用于测量与代谢相关的20个基因的表达，细胞稳态的生长和维持。适应凉爽和温暖的条件会导致整个动物的性能（代谢和生长）和潜在的基因表达模式发生可预测的变化。与适应恒定29°C的barramundi相比，适应循环温度制度并没有改变代谢或生长的分子调节。它也没有对整个动物的表现造成任何明显的影响。然而,前一组的热休克反应较高，这表明，在每天的温度循环下，barramundi对细胞伴侣的需求增加，以最大程度地减少温度对蛋白质的有害影响。我们得出的结论是，代谢和生长的遗传调节可能更依赖于每日平均温度而不是每日温度范围。
Global warming is leading to an increase in the frequency and intensity of extreme weather events, magnifying the breadth of temperatures faced by ectotherms across days and seasons. Despite the importance and ecological relevance of diurnal thermal variability, the vast majority of knowledge on gene expression patterns and physiology stems from animals acclimated to constant temperatures or in the early stages of exposure to a new temperature regime. If heterothermal environments modulate responses differently from constant thermal environments, our existing capacity to forecast impacts of climate warming may be compromised. To address this knowledge gap, we acclimated barramundi (Lates calcarifer) to 23 °C, 29 °C (optimal), 35 °C and to thermal cycling conditions (23-35 °C daily with a mean of 29 °C) and sampled liver and white muscle tissue before acclimation and after 2 and 17 weeks of acclimation. NanoString nCounter technologies were used to measure expression of 20 genes related to metabolism, growth and maintenance of cellular homeostasis. Acclimation to cool and warm conditions caused predictable changes in whole-animal performance (metabolism and growth) and the underlying gene expression patterns. Acclimation to a cycling temperature regime did not change the molecular regulation of metabolism or growth compared with barramundi acclimated to constant 29 °C, nor did it cause any discernible effects on whole-animal performance. However, the heat shock response was higher in the former group, suggesting that barramundi under a daily temperature cycle have an increased need for cellular chaperoning to minimise detrimental effects of temperature on proteins. We conclude that the genetic regulation of metabolism and growth may be more dependent on the mean daily temperature than on the daily temperature range.
