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A new role for cryptochrome in a Drosophila circadian oscillator


Cryptochromes are flavin/pterin-containing proteins that are involved in circadian clock function in Drosophila and mice. In mice, the cryptochromes Cry1 and Cry2 are integral components of the circadian oscillator within the brain1,2,3,4,5,6 and contribute to circadian photoreception in the retina7. In Drosophila, cryptochrome (CRY) acts as a photoreceptor that mediates light input to circadian oscillators in both brain and peripheral tissue8,9,10,11,12. A Drosophila cry mutant, cryb, leaves circadian oscillator function intact in central circadian pacemaker neurons but renders peripheral circadian oscillators largely arrhythmic. Although this arrhythmicity could be caused by a loss of light entrainment, it is also consistent with a role for CRY in the oscillator. A peripheral oscillator drives circadian olfactory responses in Drosophila antennae13. Here we show that CRY contributes to oscillator function and physiological output rhythms in the antenna during and after entrainment to light–dark cycles and after photic input is eliminated by entraining flies to temperature cycles. These results demonstrate a photoreceptor-independent role for CRY in the periphery and imply fundamental differences between central and peripheral oscillator mechanisms in Drosophila.

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Figure 1: Olfactory responses of wild-type and cryb mutant Drosophila under LD and DD conditions.
Figure 2: Examples of clock-gene-controlled luciferase (luc) activity rhythms from Drosophila antennae during LD.
Figure 3: EAG responses of wild-type and cryb flies during and after temperature entrainment.


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We thank R. Stanewsky for comments on the manuscript and additional tim–luc lines. This work was supported by US NIH grants to J.C.H., P.E.H. and S.E.D.

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Correspondence to Paul E. Hardin.

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Krishnan, B., Levine, J., Lynch, M. et al. A new role for cryptochrome in a Drosophila circadian oscillator. Nature 411, 313–317 (2001).

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