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Animal cryptochromes mediate magnetoreception by an unconventional photochemical mechanism


Understanding the biophysical basis of animal magnetoreception has been one of the greatest challenges in sensory biology. Recently it was discovered that the light-dependent magnetic sense of Drosophila melanogaster is mediated by the ultraviolet (UV)-A/blue light photoreceptor cryptochrome (Cry)1. Here we show, using a transgenic approach, that the photoreceptive, Drosophila-like type 1 Cry and the transcriptionally repressive, vertebrate-like type 2 Cry of the monarch butterfly (Danaus plexippus) can both function in the magnetoreception system of Drosophila and require UV-A/blue light (wavelength below 420 nm) to do so. The lack of magnetic responses for both Cry types at wavelengths above 420 nm does not fit the widely held view that tryptophan triad-generated radical pairs mediate the ability of Cry to sense a magnetic field. We bolster this assessment by using a mutant form of Drosophila and monarch type 1 Cry and confirm that the tryptophan triad pathway is not crucial in magnetic transduction. Together, these results suggest that animal Crys mediate light-dependent magnetoreception through an unconventional photochemical mechanism. This work emphasizes the utility of Drosophila transgenesis for elucidating the precise mechanisms of Cry-mediated magnetosensitivity in insects and also in vertebrates such as migrating birds.

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Figure 1: Type 1 Crys rescue light-dependent magnetoreception in Cry-deficient flies.
Figure 2: Monarch type 2 Cry rescues light-dependent magnetosensivity in Cry-deficient flies.
Figure 3: Effects of terminal tryptophan mutations on type 1 and type 2 Cry-mediated magnetosensitivity.
Figure 4: The clock proteins Tim and Cyc are not required for Drosophila magnetoreception.

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  1. Gegear, R. J., Casselman, A., Waddell, S. & Reppert, S. M. Cryptochrome mediates light-dependent magnetosensitivity in Drosophila . Nature 454, 1014–1018 (2008)

    Article  ADS  CAS  Google Scholar 

  2. Wiltschko, W. & Wiltschko, R. Magnetic orientation and magnetoreception in birds and other animals. J. Comp. Physiol. A 191, 675–693 (2005)

    Article  Google Scholar 

  3. Lohmann, K. J., Lohmann, C. M. F. & Putman, N. F. Magnetic maps in animals: nature’s GPS. J. Exp. Biol. 210, 3697–3705 (2007)

    Article  Google Scholar 

  4. Wiltschko, R., Ritz, T., Stapput, K., Thalau, P. & Wiltschko, W. Two different types of light-dependent responses to magnetic fields in birds. Curr. Biol. 15, 1518–1523 (2005)

    Article  CAS  Google Scholar 

  5. Phillips, J. B. & Borland, S. C. Wavelength specific effects of light on magnetic compass orientation of the eastern red-spotted newt Notophthalmus viridescens . Ethol. Ecol. Evol. 4, 33–42 (1992)

    Article  Google Scholar 

  6. Rodgers, C. T. & Hore, P. J. Chemical magnetoreception in birds: the radical pair mechanism. Proc. Natl Acad. Sci. USA 106, 353–360 (2009)

    Article  ADS  CAS  Google Scholar 

  7. Ritz, T., Adem, S. & Schulten, K. A model for photoreceptor-based magnetoreception in birds. Biophys. J. 78, 707–718 (2000)

    Article  CAS  Google Scholar 

  8. Maeda, K. et al. Chemical compass model of avian magnetoreception. Nature 453, 387–390 (2008)

    Article  ADS  CAS  Google Scholar 

  9. Mouritsen, H. & Ritz, T. Magnetoreception and its use in bird navigation. Curr. Opin. Neurobiol. 15, 406–414 (2005)

    Article  CAS  Google Scholar 

  10. Zhu, H. S. et al. The two CRYs of the butterfly. Curr. Biol. 15, R953–R954 (2005)

    Article  CAS  Google Scholar 

  11. Yuan, Q., Metterville, D., Briscoe, A. D. & Reppert, S. M. Insect cryptochromes: gene duplication and loss define diverse ways to construct insect circadian clocks. Mol. Biol. Evol. 24, 948–955 (2007)

    Article  CAS  Google Scholar 

  12. Öztürk, N., Song, S. H., Selby, C. P. & Sancar, A. Animal type 1 cryptochromes: analysis of the redox state of the flavin cofactor by site-directed mutagenesis. J. Biol. Chem. 283, 3256–3263 (2008)

    Article  Google Scholar 

  13. vanVickle-Chavez, S. J. & van Gelder, R. N. Action spectrum of Drosophila cryptochrome. J. Biol. Chem. 282, 10561–10566 (2007)

    Article  CAS  Google Scholar 

  14. Ritz, T., Dommer, D. H. & Phillips, J. B. Shedding light on vertebrate magnetoreception. Neuron 34, 503–506 (2002)

    Article  CAS  Google Scholar 

  15. Kaneko, M. & Hall, J. C. Neuroanatomy of cells expressing clock genes in Drosophila: transgenic manipulation of the period and timeless genes to mark the perikarya of circadian pacemaker neurons and their projections. J. Comp. Neurol. 422, 66–94 (2000)

    Article  CAS  Google Scholar 

  16. Zhu, H. S. et al. Cryptochromes define a novel circadian clock mechanism in monarch butterflies that may underlie sun compass navigation. PLoS Biol. 6, 138–155 (2008)

    Article  CAS  Google Scholar 

  17. Tu, D. C., Batten, M. L., Palczewski, K. & Van Gelder, R. N. Nonvisual photoreception in the chick iris. Science 306, 129–131 (2004)

    Article  ADS  CAS  Google Scholar 

  18. Hoang, N. et al. Human and Drosophila cryptochromes are light activated by flavin photoreduction in living cells. PLoS Biol. 6, 1559–1569 (2008)

    CAS  Google Scholar 

  19. Berndt, A. et al. A novel photoreaction mechanism for the circadian blue light photoreceptor Drosophila cryptochrome. J. Biol. Chem. 282, 13011–13021 (2007)

    Article  CAS  Google Scholar 

  20. Song, S. H. et al. Formation and function of flavin anion radical in cryptochrome 1 blue-light photoreceptor of monarch butterfly. J. Biol. Chem. 282, 17608–17612 (2007)

    Article  CAS  Google Scholar 

  21. Solov’yov, I. A. & Schulten, K. Magnetoreception through cryptochrome may involve superoxide. Biophys. J. 96, 4804–4813 (2009)

    Article  ADS  Google Scholar 

  22. Hogben, H. J., Efimova, O., Wagner-Rundell, N., Timmel, C. R. & Hore, P. J. Possible involvement of superoxide and dioxygen with cryptochrome in avian magnetoreception: origin of Zeeman resonances observed by in vivo EPR spectroscopy. Chem. Phys. Lett. 480, 118–122 (2009)

    Article  ADS  CAS  Google Scholar 

  23. Öztürk, N. et al. Structure and function of animal cryptochromes. Cold Spring Harb. Symp. Quant. Biol. 72, 119–131 (2007)

    Article  Google Scholar 

  24. Yoshii, T., Ahmad, M. & Helfrich-Forster, C. Cryptochrome mediates light-dependent magnetosensitivity of Drosophila’s circadian clock. PLoS Biol. 7, 813–819 (2009)

    Article  Google Scholar 

  25. Stanewsky, R. Genetic analysis of the circadian system in Drosophila melanogaster and mammals. J. Neurobiol. 54, 111–147 (2003)

    Article  CAS  Google Scholar 

  26. Rutila, J. E. et al. CYCLE is a second bHLH-PAS clock protein essential for circadian rhythmicity and transcription of Drosophila period and timeless. Cell 93, 805–814 (1998)

    Article  CAS  Google Scholar 

  27. Sheeba, V., Gu, H., Sharma, V. K., O’Dowd, D. K. & Holmes, T. C. Circadian- and light-dependent regulation of resting membrane potential and spontaneous action potential firing of Drosophila circadian pacemaker neurons. J. Neurophysiol. 99, 976–988 (2008)

    Article  Google Scholar 

  28. Reppert, S. M. A colorful model of the circadian clock. Cell 124, 233–236 (2006)

    Article  CAS  Google Scholar 

  29. Emery, P., So, W. V., Kaneko, M., Hall, J. C. & Rosbash, M. CRY, a Drosophila clock and light-regulated cryptochrome, is a major contributor to circadian rhythm resetting and photosensitivity. Cell 95, 669–679 (1998)

    Article  CAS  Google Scholar 

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We thank Q. Yuan for performing the assays in Fig. 3d and the cryptochrome alignments in Supplementary Fig. 1, and P. Emery, C. Merlin and D. R. Weaver for discussions. This work was supported by a grant from the National Institutes of Health.

Author Contributions All authors contributed to experimental design, execution, data analysis and writing the paper.

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Correspondence to Robert J. Gegear or Steven M. Reppert.

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Gegear, R., Foley, L., Casselman, A. et al. Animal cryptochromes mediate magnetoreception by an unconventional photochemical mechanism. Nature 463, 804–807 (2010).

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