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Published on: March 14, 2012
Avian ultraviolet/violet cones identified as probable magnetoreceptors
Christine Niessner1, Susanne Denzau, Julia Christina Gross
1Fachbereich Biowissenschaften der J.W. Goethe-Universität Frankfurt, Frankfurt am Main, Germany.
Plos One
|June 8, 2011
Summary
Researchers found cryptochrome 1a (Cry1a) in the UV/V cones of bird retinas, supporting its role in magnetic compass orientation via the Radical-Pair-Model. This identifies a key molecule for avian navigation.
Area of Science:
- Avian biology
- Neuroethology
- Biophysics
Background:
- The Radical-Pair-Model suggests birds use cryptochromes in specialized eye photopigments for magnetic compass orientation.
- The precise subcellular location of these cryptochromes in the retina was previously unknown.
Purpose of the Study:
- To determine the subcellular localization of cryptochrome 1a (Cry1a) in the retinas of European robins and domestic chickens.
- To investigate the structural basis for Cry1a's potential role in avian magnetoreception.
Main Methods:
- Localization studies of Cry1a in the retinas of *Erithacus rubecula* and *Gallus gallus*.
- Utilized electron microscopy to examine Cry1a's subcellular arrangement.
- Employed cell fractionation to determine Cry1a's association with cellular membranes.
Main Results:
- Cry1a was exclusively found in ultraviolet/violet (UV/V) cones across the retinas of both species.
- Electron microscopy revealed Cry1a organized in ordered bands along the outer segment membrane discs.
- Cell fractionation indicated Cry1a is associated with the membrane fraction.
Conclusions:
- Provides the first structural evidence for Cry1a within a sensory structure consistent with the Radical-Pair-Model's requirements.
- Identifies UV/V cones as likely magnetoreceptors, supporting Cry1a as the molecule mediating magnetic direction information.
- Offers a significant histological foundation for the Radical-Pair-Model of avian magnetic compass orientation.
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