Section of Genetics, Ecology and Evolution, Department of Biology, Aarhus University, Aarhus C, Denmark.
Mol Ecol. 2022 Jun;31(11):3174-3191. doi: 10.1111/mec.16463. Epub 2022 May 5.
Adaptation to environmental variability is a prerequisite for species' persistence in their natural environments. With climate change predicted to increase the frequency and severity of temperature fluctuations, ectothermic organisms may increasingly depend on acclimation capacity to accommodate thermal variability. To elucidate the molecular basis of fluctuating temperature-induced phenotypic plasticity, we investigated heat tolerance and the mechanisms induced by acclimation to thermal variability as compared to those seen at constant temperature. We ran genome-wide transcriptomic analysis on Drosophila melanogaster subjected to acclimation at constant (19 ± 0°C) and fluctuating (19 ± 8°C) temperatures and contrasted the induction of molecular mechanisms in adult males, adult females and larvae. We found life stage- and sex-specific dynamics of the acclimation responses to fluctuating temperatures. Adult flies exposed to temperature fluctuations showed a constitutive improvement in heat tolerance while heat tolerance of larvae tracked thermal fluctuations. A constitutive down-regulation of gene expression was observed for several genes in the larvae exposed to fluctuations. Our results for adult females showed that, for several genes, fluctuating temperature acclimation resulted in canalization of gene expression. Both transcriptional and post-transcriptional machinery were greatly affected by fluctuations in adult males. Gene ontology analysis showed enrichment of the heat stress response involving several major heat shock proteins in both larvae and adults exposed to fluctuating temperatures, even though fluctuations were in a benign range of temperatures. Finally, molecular mechanisms related to environmental sensing seem to be an important component of insect responses to thermal variability.
适应环境变异性是物种在其自然环境中生存的前提。随着气候变化预计会增加温度波动的频率和强度，变温动物可能越来越依赖于适应能力来适应热变异性。为了阐明波动温度诱导表型可塑性的分子基础，我们研究了耐热性以及与恒温相比，适应温度变异性所诱导的机制。我们对在恒温（19 ± 0°C）和波动温度（19 ± 8°C）下适应的黑腹果蝇进行了全基因组转录组分析，并对比了成年雄性、成年雌性和幼虫中诱导分子机制的情况。我们发现，对波动温度的适应反应存在生命阶段和性别特异性的动态变化。暴露于温度波动的成年果蝇表现出热耐受性的固有改善，而幼虫的热耐受性则与温度波动相吻合。暴露于波动的幼虫中，有几个基因的表达出现了组成型下调。我们对成年雌性的研究结果表明，对于几个基因，波动温度适应导致了基因表达的 canalization。波动对成年雄性的转录和转录后机制都有很大的影响。基因本体分析表明，热应激反应涉及几个主要热休克蛋白在暴露于波动温度的幼虫和成虫中富集，尽管波动温度处于良性范围。最后，与环境感应相关的分子机制似乎是昆虫对热变异性反应的一个重要组成部分。
