Data from: Thermal fluctuations affect the transcriptome through mechanisms independent of average temperature

Terrestrial ectotherms are challenged by variation in both mean and variance of temperature. Phenotypic plasticity (thermal acclimation) might mitigate adverse effects, however, we lack a fundamental understanding of the molecular mechanisms of thermal acclimation and how they are affected by fluctuating temperature. Here we investigated the effect of thermal acclimation in Drosophila melanogaster on critical thermal maxima (CTmax) and associated global gene expression profiles as induced by two constant and two ecologically relevant (non-stressful) diurnally fluctuating temperature regimes. Both mean and fluctuation of temperature contributed to thermal acclimation and affected the transcriptome. The transcriptomic response to mean temperatures comprised modification of a major part of the transcriptome, while the response to fluctuations affected a much smaller set of genes, which was highly independent of both the response to a change in mean temperature and to the classic heat shock response. Although the independent transcriptional effects caused by fluctuations were relatively small, they are likely to contribute to our understanding of thermal adaptation. We provide evidence that environmental sensing, particularly phototransduction, is a central mechanism underlying the regulation of thermal acclimation to fluctuating temperatures. Thus, genes and pathways involved in phototransduction are likely of importance in fluctuating climates.

陆生外温动物同时面临温度均值与温度方差波动带来的生存挑战。尽管表型可塑性（phenotypic plasticity）——即热驯化（thermal acclimation）——可缓解此类负面影响，但目前学界对热驯化的分子机制及其受波动温度影响的方式仍缺乏基本认知。本研究以黑腹果蝇（Drosophila melanogaster）为实验材料，探究了两种恒定温度与两种生态相关（无胁迫性）的昼夜波动温度模式诱导的热驯化对其临界热极限（CTmax）及关联的全球基因表达谱的影响。研究结果显示，温度均值与温度波动均参与调控热驯化过程，并对转录组产生影响。针对温度均值的转录组响应涉及转录组的大部分区域修饰，而针对温度波动的转录组响应仅影响少量基因，且该响应与温度均值变化诱导的转录组响应及经典热激响应均高度独立。尽管波动温度引发的独立转录调控效应相对微弱，但该效应或有助于加深学界对热适应机制的理解。本研究证实，环境感知尤其是光转导（phototransduction）通路，是调控波动温度下热驯化过程的核心机制。因此，参与光转导的基因与通路在波动气候环境中或具有关键作用。