title: Temperature-dependent resetting of the molecular circadian oscillator in Drosophila.
abstract: 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.
authors.affiliation: Department of Biology, University of Virginia, Charlottesville, VA 22904-4328, USA.
authors.forename: Tadahiro
authors.initials: T
authors.lastname: Goda
authors.affiliation: Department of Biology, University of Virginia, Charlottesville, VA 22904-4328, USA.
authors.forename: Brandi
authors.initials: B
authors.lastname: Sharp
authors.affiliation: Department of Biology, University of Virginia, Charlottesville, VA 22904-4328, USA Centre for Biological Sciences and Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK hw3a11@soton.ac.uk.
authors.forename: Herman
authors.initials: H
authors.lastname: Wijnen
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D002940:Circadian Rhythm; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics / Q000502:physiology*; D056950:Period Circadian Proteins / Q000235:genetics* / Q000378:metabolism; D013696:Temperature
chemical_list: D029721:Drosophila Proteins; C539040:PER protein, Drosophila; D056950:Period Circadian Proteins; C096445:tim protein, Drosophila
keywords: Drosophila melanogaster; circadian clock; entrainment; temperature; transcriptional regulation