Data from: Temperature-dependent resetting of the molecular circadian oscillator in Drosophila.

Circadian clocks responsible for daily time keeping in a wide range of organisms synchronize to daily temperature cycles via pathways that remain poorly understood. To address this problem from the perspective of the molecular oscillator, we monitored temperature-dependent resetting of four of its core components in the fruitfly Drosophila melanogaster: the transcripts and proteins for the clock genes period (per) and timeless (tim). The molecular circadian cycle in adult heads exhibited parallel responses to temperature-mediated resetting at the levels of per transcript, tim transcript and TIM protein. Early phase adjustment specific to per transcript rhythms was explained by clock-independent temperature-driven transcription of per. The cold-induced expression of Drosophila per contrasts with the previously reported heat-induced regulation of mammalian Period 2. An altered and more readily re-entrainable temperature-synchronized circadian oscillator that featured temperature-driven per transcript rhythms and phase-shifted TIM and PER protein rhythms was found for flies of the ‘Tim 4’ genotype, which lacked daily tim transcript oscillations but maintained post-transcriptional temperature entrainment of tim expression. The accelerated molecular and behavioural temperature entrainment observed for Tim 4 flies indicates that clock-controlled tim expression constrains the rate of temperature cycle-mediated circadian resetting.

在众多生物中负责日常计时的昼夜节律钟（circadian clock），可通过尚未完全阐明的通路与每日温度周期实现同步。为从分子振荡器（molecular oscillator）的视角解决这一科学问题，我们对黑腹果蝇（Drosophila melanogaster）体内4个核心组分的温度依赖性节律重置进行了监测，检测对象为生物钟基因period（per）与timeless（tim）的转录本及对应蛋白质。成虫头部的分子昼夜节律周期，在per转录本、tim转录本以及TIM蛋白水平上，均表现出对温度介导节律重置的平行响应。仅针对per转录本节律的早期相位调整，可通过不依赖生物钟的温度驱动型per转录过程加以解释。果蝇per基因的冷诱导表达模式，与此前报道的哺乳动物Period 2的热诱导调控特征形成显著差异。针对‘Tim 4’基因型的果蝇，我们观测到一类发生改变且更易重新同步的温度同步化昼夜节律振荡器：该振荡器具备温度驱动的per转录本节律，同时伴有相位偏移的TIM和PER蛋白节律。这类果蝇缺乏每日tim转录本的振荡表达，但仍可维持tim表达的转录后温度同步化过程。我们在Tim 4果蝇中观测到的分子与行为层面的温度同步化加速现象表明，受生物钟调控的tim表达会限制温度周期介导的昼夜节律重置速率。