Magnetoreception in birds : I. immunohistochemical studies concerning the cryptochrome cycle

  • Cryptochrome 1a, located in the UV/violet-sensitive cones in the avian retina, is discussed as receptor molecule for the magnetic compass of birds. Our previous immunohistochemical studies of chicken retinae with an antiserum that labelled only activated cryptochrome 1a had shown activation of cryptochrome 1a under 373 nm UV, 424 nm blue, 502 nm turquoise and 565 nm green light. Green light, however, does not allow the first step of photoreduction of oxidized cryptochromes to the semiquinone. As the chickens had been kept under ‘white’ light before, we suggested that there was a supply of the semiquinone present at the beginning of the exposure to green light, which could be further reduced and then re-oxidized. To test this hypothesis, we exposed chickens to various wavelengths (1) for 30 min after being kept in daylight, (2) for 30 min after a 30 min pre-exposure to total darkness, and (3) for 1 h after being kept in daylight. In the first case, we found activated cryptochrome 1a under UV, blue, turquoise and green light; in the second two cases we found activated cryptochrome 1a only under UV to turquoise light, where the complete redox cycle of cryptochrome can run, but not under green light. This observation is in agreement with the hypothesis that activated cryptochrome 1a is found as long as there is some of the semiquinone left, but not when the supply is depleted. It supports the idea that the crucial radical pair for magnetoreception is generated during re-oxidation.

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Author:Christine Nießner, Susanne DenzauGND, Leo Peichl, Wolfgang WiltschkoGND, Roswitha WiltschkoORCiDGND
Pubmed Id:
Parent Title (German):Journal of experimental biology
Publisher:Company of Biologists
Place of publication:Cambridge
Document Type:Article
Date of Publication (online):2016/11/28
Date of first Publication:2014/12/03
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2016/11/28
Tag:Activated Cry1a; Cryptochrome 1a; Flavin cycle; Magnetic compass; Photoreduction; Radical pair mechanisms
Page Number:4
First Page:4221
Last Page:4224
© 2014. Published by The Company of Biologists Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.
Institutes:Biowissenschaften / Biowissenschaften
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 59 Tiere (Zoologie) / 590 Tiere (Zoologie)
Licence (German):License LogoCreative Commons - Namensnennung 3.0