title: Temperature compensation and temperature sensation in the circadian clock.
abstract: All known circadian clocks have an endogenous period that is remarkably insensitive to temperature, a property known as temperature compensation, while at the same time being readily entrained by a diurnal temperature oscillation. Although temperature compensation and entrainment are defining features of circadian clocks, their mechanisms remain poorly understood. Most models presume that multiple steps in the circadian cycle are temperature-dependent, thus facilitating temperature entrainment, but then insist that the effect of changes around the cycle sums to zero to enforce temperature compensation. An alternative theory proposes that the circadian oscillator evolved from an adaptive temperature sensor: a gene circuit that responds only to temperature changes. This theory implies that temperature changes should linearly rescale the amplitudes of clock component oscillations but leave phase relationships and shapes unchanged. We show using timeless luciferase reporter measurements and Western blots against TIMELESS protein that this prediction is satisfied by the Drosophila circadian clock. We also review evidence for pathways that couple temperature to the circadian clock, and show previously unidentified evidence for coupling between the Drosophila clock and the heat-shock pathway.
authors.affiliation: Laboratory of Genetics, Rockefeller University, New York, NY 10065; Center for Physics and Biology, Rockefeller University, New York, NY 10065.
authors.forename: Philip B
authors.initials: PB
authors.lastname: Kidd
authors.affiliation: Laboratory of Genetics, Rockefeller University, New York, NY 10065;
authors.forename: Michael W
authors.initials: MW
authors.lastname: Young
authors.affiliation: Center for Physics and Biology, Rockefeller University, New York, NY 10065 siggiae@rockefeller.edu.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Siggia
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D057906:Circadian Clocks / Q000502:physiology*; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster; D018869:Heat-Shock Response / Q000502:physiology*; D008954:Models, Biological; D013697:Thermosensing / Q000502:physiology*
chemical_list: D029721:Drosophila Proteins; C096445:tim protein, Drosophila
keywords: circadian clock; mathematical models; temperature compensation