Temperature synchronization of the Drosophila circadian clock.
BACKGROUND
Circadian clocks are synchronized by both light:dark cycles and by temperature fluctuations. Although it has long been known that temperature cycles can robustly entrain Drosophila locomotor rhythms, nothing is known about the molecular mechanisms involved.


RESULTS
We show here that temperature cycles induce synchronized behavioral rhythms and oscillations of the clock proteins PERIOD and TIMELESS in constant light, a situation that normally leads to molecular and behavioral arrhythmicity. We show that expression of the Drosophila clock gene period can be entrained by temperature cycles in cultured body parts and isolated brains. Further, we show that the phospholipase C encoded by the norpA gene contributes to thermal entrainment, suggesting that a receptor-coupled transduction cascade signals temperature changes to the circadian clock. We initiated the further genetic dissection of temperature-entrainment and isolated the novel Drosophila mutation nocte, which is defective in molecular and behavioral entrainment by temperature cycles but synchronizes normally to light:dark cycles.


CONCLUSIONS
We conclude that temperature synchronization of the circadian clock is a tissue-autonomous process that is able to override the arrhythmia-inducing effects of constant light. Our data suggest that it involves a cell-autonomous signal-transduction cascade from a thermal receptor to the circadian clock. This process includes the function of phospholipase C and the product specified by the novel mutation nocte.
Glaser
Franz T
FT
Institut für Zoologie, Universität Regensburg, 93040 Regensburg, Germany.
Stanewsky
Ralf
R
D000818:Animals; D030801:Animals, Genetically Modified; D001683:Biological Clocks / Q000502:physiology*; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology*; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D008124:Locomotion / Q000502:physiology; D008156:Luciferases / Q000378:metabolism; D016296:Mutagenesis; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D056950:Period Circadian Proteins; D017440:Photoperiod; D015398:Signal Transduction; D013696:Temperature; D010738:Type C Phospholipases / Q000378:metabolism
D029721:Drosophila Proteins; D009687:Nuclear Proteins; C539040:PER protein, Drosophila; D056950:Period Circadian Proteins; C096445:tim protein, Drosophila; D008156:Luciferases; D010738:Type C Phospholipases