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The amphibian magnetic sense(s). J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2022; 208:723-742. [PMID: 36269404 DOI: 10.1007/s00359-022-01584-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 10/02/2022] [Accepted: 10/03/2022] [Indexed: 12/14/2022]
Abstract
Sensitivity to the earth's magnetic field is the least understood of the major sensory systems, despite being virtually ubiquitous in animals and of widespread interest to investigators in a wide range of fields from behavioral ecology to quantum physics. Although research on the use of magnetic cues by migratory birds, fish, and sea turtles is more widely known, much of our current understanding of the functional properties of vertebrate magnetoreception has come from research on amphibians. Studies of amphibians established the presence of a light-dependent magnetic compass, a second non-light-dependent mechanism involving particles of magnetite and/or maghemite, and an interaction between these two magnetoreception mechanisms that underlies the "map" component of homing. Simulated magnetic displacement experiments demonstrated the use of a high-resolution magnetic map for short-range homing to breeding ponds requiring a sampling strategy to detect weak spatial gradients in the magnetic field despite daily temporal variation at least an order of magnitude greater. Overall, reliance on a magnetic map for short-range homing places greater demands on the underlying sensory detection, processing, and memory mechanisms than comparable mechanisms used by long-distance migrants. Moreover, unlike sea turtles and migratory birds, amphibians are exceptionally well suited to serve as model organisms in which to characterize the molecular and biophysical mechanisms underlying the light-dependent 'quantum compass'.
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2
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Wiltschko R, Wiltschko W. The discovery of the use of magnetic navigational information. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2022; 208:9-18. [PMID: 34476571 PMCID: PMC8918449 DOI: 10.1007/s00359-021-01507-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 08/13/2021] [Accepted: 08/19/2021] [Indexed: 12/01/2022]
Abstract
The magnetic field of the Earth provides animals with various kinds of information. Its use as a compass was discovered in the mid-1960s in birds, when it was first met with considerable skepticism, because it initially proved difficult to obtain evidence for magnetic sensitivity by conditioning experiments. Meanwhile, a magnetic compass was found to be widespread. It has now been demonstrated in members of all vertebrate classes, in mollusks and several arthropod species, in crustaceans as well as in insects. The use of the geomagnetic field as a 'map' for determining position, although already considered in the nineteenth century, was demonstrated by magnetically simulating displacements only after 2000, namely when animals, tested in the magnetic field of a distant site, responded as if they were physically displaced to that site and compensated for the displacement. Another use of the magnetic field is that as a 'sign post' or trigger: specific magnetic conditions elicit spontaneous responses that are helpful when animals reach the regions where these magnetic characteristics occur. Altogether, the geomagnetic field is a widely used valuable source of navigational information for mobile animals.
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Affiliation(s)
- Roswitha Wiltschko
- Fachbereich Biowissenschaften, Goethe-Universität Frankfurt, Max-von-Laue-Straße 13, 60438, Frankfurt am Main, Germany.
| | - Wolfgang Wiltschko
- Fachbereich Biowissenschaften, Goethe-Universität Frankfurt, Max-von-Laue-Straße 13, 60438, Frankfurt am Main, Germany
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3
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Thoss F, Bartsch B. A model of the FAD redox cycle describes the dynamics of the effect of the geomagnetic field on the human visual system. BIOLOGICAL CYBERNETICS 2017; 111:347-352. [PMID: 28776258 DOI: 10.1007/s00422-017-0725-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 07/27/2017] [Indexed: 06/07/2023]
Abstract
In experimental studies, we could show that the visual threshold of man is influenced by the geomagnetic field. One of the results was that the threshold shows periodic fluctuations when the vertical component of the field is reversed periodically. The maximum of these oscillations occurred at a period duration of 110 s. To explain this phenomenon, we chose the process that likely underlies the navigation of birds in the geomagnetic field: the light reaction of the FAD component of cryptochrome in the retina. The human retina contains cryptpochrome like the bird retina. Based on the investigations of Müller and Ahmad (J Biol Chem 286:21033-21040, 2011) and Solov'yov and Schulten (J Phys Chem B 116:1089-1099, 2012), we designed a model of the light-induced reduction and subsequent reoxidation of FAD. This model contains a radical pair, whose interconversion dynamics are affected by the geomagnetic field. The parameters of the model were partly calculated from the data of our experimental investigation and partly taken from the results of other authors. These parameters were then optimized by adjusting the model behaviour to the experimental results. The simulation of the finished model shows that the concentrations of all substances included show really oscillations with the frequency of the modelled magnetic field. After optimization of the parameters, the oscillations of FAD and FADH* show maximal amplitude at a period duration of 110 s, as was observed in the experiment. This makes it most likely that the signal, which influences the visual system, originates from FADH* (signalling state).
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Affiliation(s)
- Franz Thoss
- Carl-Ludwig-Institute of Physiology, University of Leipzig, Liebigstr. 27, 04103, Leipzig, Germany.
| | - Bengt Bartsch
- Carl-Ludwig-Institute of Physiology, University of Leipzig, Liebigstr. 27, 04103, Leipzig, Germany
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4
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Paul S, Meng L, Berger S, Grampp G, Matysik J, Wang X. The Flavin-Tryptophan Dyad F10T as a Cryptochrome Model Compound: Synthesis and Photochemistry. CHEMPHOTOCHEM 2016. [DOI: 10.1002/cptc.201600025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Shubhajit Paul
- Institut für Analytische Chemie; Universität Leipzig; Linnéstr. 3 04103 Leipzig Germany
| | - Lingqiang Meng
- Department of Chemistry and Biology; National University of Defense Technology; 410073 Changsha China
- Yanching Institute of Technology; 065200, Sanhe, Hebei China
| | - Stefan Berger
- Institut für Analytische Chemie; Universität Leipzig; Linnéstr. 3 04103 Leipzig Germany
| | - Günter Grampp
- Institut für Physikalische und Theoretische Chemie; Technische Universität Graz; Streymayrgasse 9/I 8010 Graz Austria
| | - Jörg Matysik
- Institut für Analytische Chemie; Universität Leipzig; Linnéstr. 3 04103 Leipzig Germany
| | - Xiaojie Wang
- Department of Chemistry and Biology; National University of Defense Technology; 410073 Changsha China
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5
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Qin S, Yin H, Yang C, Dou Y, Liu Z, Zhang P, Yu H, Huang Y, Feng J, Hao J, Hao J, Deng L, Yan X, Dong X, Zhao Z, Jiang T, Wang HW, Luo SJ, Xie C. A magnetic protein biocompass. NATURE MATERIALS 2016; 15:217-226. [PMID: 26569474 DOI: 10.1038/nmat4484] [Citation(s) in RCA: 176] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 10/21/2015] [Indexed: 06/05/2023]
Abstract
The notion that animals can detect the Earth's magnetic field was once ridiculed, but is now well established. Yet the biological nature of such magnetosensing phenomenon remains unknown. Here, we report a putative magnetic receptor (Drosophila CG8198, here named MagR) and a multimeric magnetosensing rod-like protein complex, identified by theoretical postulation and genome-wide screening, and validated with cellular, biochemical, structural and biophysical methods. The magnetosensing complex consists of the identified putative magnetoreceptor and known magnetoreception-related photoreceptor cryptochromes (Cry), has the attributes of both Cry- and iron-based systems, and exhibits spontaneous alignment in magnetic fields, including that of the Earth. Such a protein complex may form the basis of magnetoreception in animals, and may lead to applications across multiple fields.
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Affiliation(s)
- Siying Qin
- State Key Laboratory of Membrane Biology, Laboratory of Molecular Biophysics, School of Life Sciences, Peking University, Beijing 100871, China
| | - Hang Yin
- State Key Laboratory of Membrane Biology, Laboratory of Molecular Biophysics, School of Life Sciences, Peking University, Beijing 100871, China
| | - Celi Yang
- State Key Laboratory of Membrane Biology, Laboratory of Molecular Biophysics, School of Life Sciences, Peking University, Beijing 100871, China
| | - Yunfeng Dou
- State Key Laboratory of Membrane Biology, Laboratory of Molecular Biophysics, School of Life Sciences, Peking University, Beijing 100871, China
| | - Zhongmin Liu
- Ministry of Education Key Laboratory of Protein Science, Center for Structural Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Peng Zhang
- Key Laboratory of Protein &Peptide Pharmaceuticals, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - He Yu
- School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Yulong Huang
- Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Jing Feng
- Key Laboratory of Protein &Peptide Pharmaceuticals, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Junfeng Hao
- Center for Experimental Animal Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Jia Hao
- State Key Laboratory of Membrane Biology, Laboratory of Molecular Biophysics, School of Life Sciences, Peking University, Beijing 100871, China
| | - Lizong Deng
- Key Laboratory of Protein &Peptide Pharmaceuticals, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiyun Yan
- Key Laboratory of Protein &Peptide Pharmaceuticals, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiaoli Dong
- Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhongxian Zhao
- Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Taijiao Jiang
- Key Laboratory of Protein &Peptide Pharmaceuticals, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Hong-Wei Wang
- Ministry of Education Key Laboratory of Protein Science, Center for Structural Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shu-Jin Luo
- School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Can Xie
- State Key Laboratory of Membrane Biology, Laboratory of Molecular Biophysics, School of Life Sciences, Peking University, Beijing 100871, China
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Abstract
The ability to perceive geomagnetic fields (GMFs) represents a fascinating biological phenomenon. Studies on transgenic flies have provided evidence that photosensitive Cryptochromes (Cry) are involved in the response to magnetic fields (MFs). However, none of the studies tackled the problem of whether the Cry-dependent magnetosensitivity is coupled to the sole MF presence or to the direction of MF vector. In this study, we used gene silencing and a directional MF to show that mammalian-like Cry2 is necessary for a genuine directional response to periodic rotations of the GMF vector in two insect species. Longer wavelengths of light required higher photon fluxes for a detectable behavioral response, and a sharp detection border was present in the cyan/green spectral region. Both observations are consistent with involvement of the FADox, FAD(•-) and FADH(-) redox forms of flavin. The response was lost upon covering the eyes, demonstrating that the signal is perceived in the eye region. Immunohistochemical staining detected Cry2 in the hemispherical layer of laminal glia cells underneath the retina. Together, these findings identified the eye-localized Cry2 as an indispensable component and a likely photoreceptor of the directional GMF response. Our study is thus a clear step forward in deciphering the in vivo effects of GMF and supports the interaction of underlying mechanism with the visual system.
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Wiltschko R, Thalau P, Gehring D, Nießner C, Ritz T, Wiltschko W. Magnetoreception in birds: the effect of radio-frequency fields. J R Soc Interface 2015; 12:rsif.2014.1103. [PMID: 25540238 DOI: 10.1098/rsif.2014.1103] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The avian magnetic compass, probably based on radical pair processes, works only in a narrow functional window around the local field strength, with cryptochrome 1a as most likely receptor molecule. Radio-frequency fields in the MHz range have been shown to disrupt the birds' orientation, yet the nature of this interference is still unclear. In an immuno-histological study, we tested whether the radio-frequency fields interfere with the photoreduction of cryptochrome, but this does not seem to be the case. In behavioural studies, birds were not able to adjust to radio-frequency fields like they are able to adjust to static fields outside the normal functional range: neither a 2-h pre-exposure in a 7.0 MHz field, 480 nT, nor a 7-h pre-exposure in a 1.315 MHz field, 15 nT, allowed the birds to regain their orientation ability. This inability to adjust to radio-frequency fields suggests that these fields interfere directly with the primary processes of magnetoreception and therefore disable the avian compass as long as they are present. They do not have lasting adverse after-effects, however, as birds immediately after exposure to a radio-frequency field were able to orient in the local geomagnetic field.
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Affiliation(s)
- Roswitha Wiltschko
- FB Biowissenschaften, J.W.Goethe-Universität Frankfurt, Max von Laue Straße 13, D-60438 Frankfurt am Main, Germany
| | - Peter Thalau
- FB Biowissenschaften, J.W.Goethe-Universität Frankfurt, Max von Laue Straße 13, D-60438 Frankfurt am Main, Germany
| | - Dennis Gehring
- FB Biowissenschaften, J.W.Goethe-Universität Frankfurt, Max von Laue Straße 13, D-60438 Frankfurt am Main, Germany
| | - Christine Nießner
- FB Biowissenschaften, J.W.Goethe-Universität Frankfurt, Max von Laue Straße 13, D-60438 Frankfurt am Main, Germany
| | - Thorsten Ritz
- Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575, USA
| | - Wolfgang Wiltschko
- FB Biowissenschaften, J.W.Goethe-Universität Frankfurt, Max von Laue Straße 13, D-60438 Frankfurt am Main, Germany
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8
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Kishkinev DA, Chernetsov NS. Magnetoreception systems in birds: A review of current research. ACTA ACUST UNITED AC 2015. [DOI: 10.1134/s2079086415010041] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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9
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Lee AA, Lau JCS, Hogben HJ, Biskup T, Kattnig DR, Hore PJ. Alternative radical pairs for cryptochrome-based magnetoreception. J R Soc Interface 2014; 11:20131063. [PMID: 24671932 DOI: 10.1098/rsif.2013.1063] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
There is growing evidence that the remarkable ability of animals, in particular birds, to sense the direction of the Earth's magnetic field relies on magnetically sensitive photochemical reactions of the protein cryptochrome. It is generally assumed that the magnetic field acts on the radical pair [FAD•- TrpH•+] formed by the transfer of an electron from a group of three tryptophan residues to the photo-excited flavin adenine dinucleotide cofactor within the protein. Here, we examine the suitability of an [FAD•- Z•] radical pair as a compass magnetoreceptor, where Z• is a radical in which the electron spin has no hyperfine interactions with magnetic nuclei, such as hydrogen and nitrogen. Quantum spin dynamics simulations of the reactivity of [FAD•- Z•] show that it is two orders of magnitude more sensitive to the direction of the geomagnetic field than is [FAD•- TrpH•+] under the same conditions (50 µT magnetic field, 1 µs radical lifetime). The favourable magnetic properties of [FAD•- Z•] arise from the asymmetric distribution of hyperfine interactions among the two radicals and the near-optimal magnetic properties of the flavin radical. We close by discussing the identity of Z• and possible routes for its formation as part of a spin-correlated radical pair with an FAD radical in cryptochrome.
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Affiliation(s)
- Alpha A Lee
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, , Oxford OX1 3QZ, UK
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10
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Holland RA, Helm B. A strong magnetic pulse affects the precision of departure direction of naturally migrating adult but not juvenile birds. J R Soc Interface 2013; 10:20121047. [PMID: 23389901 DOI: 10.1098/rsif.2012.1047] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The mechanisms by which migratory birds achieve their often spectacular navigational performance are still largely unclear, but perception of cues from the Earth's magnetic field is thought to play a role. Birds that possess migratory experience can use map-based navigation, which may involve a receptor that uses ferrimagnetic material for detecting gradients in the magnetic field. Such a mechanism can be experimentally disrupted by applying a strong magnetic pulse that re-magnetizes ferrimagnetic materials. In captivity, this treatment indeed affected bearings of adult but not of naive juvenile birds. However, field studies, which expose birds to various navigational cues, yielded mixed results. Supportive studies were difficult to interpret because they were conducted in spring when all age groups navigate back to breeding areas. The present study, therefore, applied a magnetic pulse treatment in autumn to naturally migrating, radio-tagged European robins. We found that, although overall bearings were seasonally correct, orientation of adult but not juvenile robins was compromised by a pulse. Pulsed adults that departed within 10 days of treatment failed to show significant orientation and deviated more from mean migration direction than adult controls and juveniles. Thus, our data give field-based support for a possible ferrimagnetic map-sense during bird migration.
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Affiliation(s)
- Richard A Holland
- Department for Migration and Immune-ecology, Max Planck Institute for Ornithology, Schlossallee 2, Radolfzell 78315, Germany.
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11
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Phillips JB, Muheim R, Jorge PE. A behavioral perspective on the biophysics of the light-dependent magnetic compass: a link between directional and spatial perception? ACTA ACUST UNITED AC 2011; 213:3247-55. [PMID: 20833916 DOI: 10.1242/jeb.020792] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In terrestrial organisms, sensitivity to the Earth's magnetic field is mediated by at least two different magnetoreception mechanisms, one involving biogenic ferromagnetic crystals (magnetite/maghemite) and the second involving a photo-induced biochemical reaction that forms long-lasting, spin-coordinated, radical pair intermediates. In some vertebrate groups (amphibians and birds), both mechanisms are present; a light-dependent mechanism provides a directional sense or 'compass', and a non-light-dependent mechanism underlies a geographical-position sense or 'map'. Evidence that both magnetite- and radical pair-based mechanisms are present in the same organisms raises a number of interesting questions. Why has natural selection produced magnetic sensors utilizing two distinct biophysical mechanisms? And, in particular, why has natural selection produced a compass mechanism based on a light-dependent radical pair mechanism (RPM) when a magnetite-based receptor is well suited to perform this function? Answers to these questions depend, to a large degree, on how the properties of the RPM, viewed from a neuroethological rather than a biophysical perspective, differ from those of a magnetite-based magnetic compass. The RPM is expected to produce a light-dependent, 3-D pattern of response that is axially symmetrical and, in some groups of animals, may be perceived as a pattern of light intensity and/or color superimposed on the visual surroundings. We suggest that the light-dependent magnetic compass may serve not only as a source of directional information but also provide a spherical coordinate system that helps to interface metrics of distance, direction and spatial position.
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Affiliation(s)
- John B Phillips
- Department of Biological Sciences, Virginia Tech, 4100 Derring Hall, Blacksburg, VA 24061-0406, USA
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12
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Holland RA. Differential effects of magnetic pulses on the orientation of naturally migrating birds. J R Soc Interface 2010; 7:1617-25. [PMID: 20453067 PMCID: PMC2988258 DOI: 10.1098/rsif.2010.0159] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Accepted: 04/16/2010] [Indexed: 11/12/2022] Open
Abstract
In migratory passerine birds, strong magnetic pulses are thought to be diagnostic of the remagnetization of iron minerals in a putative sensory system contained in the beak. Previous evidence suggests that while such a magnetic pulse affects the orientation of migratory birds in orientation cages, no effect was present when pulse-treated birds were tested in natural migration. Here we show that two migrating passerine birds treated with a strong magnetic pulse, designed to alter the magnetic sense, migrated in a direction that differed significantly from that of controls when tested in natural conditions. The orientation of treated birds was different depending on the alignment of the pulse with respect to the magnetic field. These results can aid in advancing understanding of how the putative iron-mineral-based receptors found in birds' beaks may be used to detect and signal the intensity and/or direction of the Earth's magnetic field.
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Affiliation(s)
- Richard A Holland
- Department of Migration and Immunoecology, Max Planck Institute for Ornithology, Radolfzell, Germany.
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13
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Light-dependent magnetic compass in Iberian green frog tadpoles. Naturwissenschaften 2010; 97:1077-88. [DOI: 10.1007/s00114-010-0730-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Revised: 10/12/2010] [Accepted: 10/13/2010] [Indexed: 10/18/2022]
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14
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Lau JCS, Wagner-Rundell N, Rodgers CT, Green NJB, Hore PJ. Effects of disorder and motion in a radical pair magnetoreceptor. J R Soc Interface 2010; 7 Suppl 2:S257-64. [PMID: 20007172 PMCID: PMC2844003 DOI: 10.1098/rsif.2009.0399.focus] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Accepted: 11/18/2009] [Indexed: 11/12/2022] Open
Abstract
A critical requirement in the proposed chemical model of the avian magnetic compass is that the molecules that play host to the magnetically sensitive radical pair intermediates must be immobilized and rotationally ordered within receptor cells. Rotational disorder would cause the anisotropic responses of differently oriented radical pairs within the same cell to interfere destructively, while rapid molecular rotation would tend to average the crucial anisotropic magnetic interactions and induce electron spin relaxation, reducing the sensitivity to the direction of the geomagnetic field. So far, experimental studies have been able to shed little light on the required degree of ordering and immobilization. To address this question, computer simulations have been performed on a collection of radical pairs undergoing restricted rigid-body rotation, coherent anisotropic spin evolution, electron spin relaxation and spin-selective recombination reactions. It is shown that the ordering and motional constraints necessary for efficient magnetoreception can be simultaneously satisfied if the radical pairs are uniaxially ordered with a moderate order parameter and if their motional correlation time is longer than about a quarter of their lifetime.
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Affiliation(s)
| | | | | | | | - P. J. Hore
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
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15
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Vanderstraeten J, Gillis P. Theoretical evaluation of magnetoreception of power-frequency fields. Bioelectromagnetics 2010; 31:371-9. [DOI: 10.1002/bem.20568] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Keary N, Ruploh T, Voss J, Thalau P, Wiltschko R, Wiltschko W, Bischof HJ. Oscillating magnetic field disrupts magnetic orientation in Zebra finches, Taeniopygia guttata. Front Zool 2009; 6:25. [PMID: 19852792 PMCID: PMC2774300 DOI: 10.1186/1742-9994-6-25] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Accepted: 10/23/2009] [Indexed: 11/14/2022] Open
Abstract
Background Zebra finches can be trained to use the geomagnetic field as a directional cue for short distance orientation. The physical mechanisms underlying the primary processes of magnetoreception are, however, largely unknown. Two hypotheses of how birds perceive magnetic information are mainly discussed, one dealing with modulation of radical pair processes in retinal structures, the other assuming that iron deposits in the upper beak of the birds are involved. Oscillating magnetic fields in the MHz range disturb radical pair mechanisms but do not affect magnetic particles. Thus, application of such oscillating fields in behavioral experiments can be used as a diagnostic tool to decide between the two alternatives. Methods In a setup that eliminates all directional cues except the geomagnetic field zebra finches were trained to search for food in the magnetic north/south axis. The birds were then tested for orientation performance in two magnetic conditions. In condition 1 the horizontal component of the geomagnetic field was shifted by 90 degrees using a helmholtz coil. In condition 2 a high frequently oscillating field (1.156 MHz) was applied in addition to the shifted field. Another group of birds was trained to solve the orientation task, but with visual landmarks as directional cue. The birds were then tested for their orientation performance in the same magnetic conditions as applied for the first experiment. Results The zebra finches could be trained successfully to orient in the geomagnetic field for food search in the north/south axis. They were also well oriented in test condition 1, with the magnetic field shifted horizontally by 90 degrees. In contrast, when the oscillating field was added, the directional choices during food search were randomly distributed. Birds that were trained to visually guided orientation showed no difference of orientation performance in the two magnetic conditions. Conclusion The results indicate that zebra finches use a receptor that bases on radical pair processes for sensing the direction of the earth magnetic field in this short distance orientation behavior.
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Affiliation(s)
- Nina Keary
- Lehrstuhl Verhaltensforschung, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
| | - Tim Ruploh
- Lehrstuhl Verhaltensforschung, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
| | - Joe Voss
- Lehrstuhl Verhaltensforschung, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
| | - Peter Thalau
- FB Biowissenschaften, J. W. Goethe-Universität, Siesmayerstr. 70, D-60054 Frankfurt/Main, Germany
| | - Roswitha Wiltschko
- FB Biowissenschaften, J. W. Goethe-Universität, Siesmayerstr. 70, D-60054 Frankfurt/Main, Germany
| | - Wolfgang Wiltschko
- FB Biowissenschaften, J. W. Goethe-Universität, Siesmayerstr. 70, D-60054 Frankfurt/Main, Germany
| | - Hans-Joachim Bischof
- Lehrstuhl Verhaltensforschung, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
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Cryptochrome mediates light-dependent magnetosensitivity of Drosophila's circadian clock. PLoS Biol 2009; 7:e1000086. [PMID: 19355790 PMCID: PMC2667543 DOI: 10.1371/journal.pbio.1000086] [Citation(s) in RCA: 397] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Accepted: 03/03/2009] [Indexed: 11/20/2022] Open
Abstract
Since 1960, magnetic fields have been discussed as Zeitgebers for circadian clocks, but the mechanism by which clocks perceive and process magnetic information has remained unknown. Recently, the radical-pair model involving light-activated photoreceptors as magnetic field sensors has gained considerable support, and the blue-light photoreceptor cryptochrome (CRY) has been proposed as a suitable molecule to mediate such magnetosensitivity. Since CRY is expressed in the circadian clock neurons and acts as a critical photoreceptor of Drosophila's clock, we aimed to test the role of CRY in magnetosensitivity of the circadian clock. In response to light, CRY causes slowing of the clock, ultimately leading to arrhythmic behavior. We expected that in the presence of applied magnetic fields, the impact of CRY on clock rhythmicity should be altered. Furthermore, according to the radical-pair hypothesis this response should be dependent on wavelength and on the field strength applied. We tested the effect of applied static magnetic fields on the circadian clock and found that flies exposed to these fields indeed showed enhanced slowing of clock rhythms. This effect was maximal at 300 μT, and reduced at both higher and lower field strengths. Clock response to magnetic fields was present in blue light, but absent under red-light illumination, which does not activate CRY. Furthermore, cryb and cryOUT mutants did not show any response, and flies overexpressing CRY in the clock neurons exhibited an enhanced response to the field. We conclude that Drosophila's circadian clock is sensitive to magnetic fields and that this sensitivity depends on light activation of CRY and on the applied field strength, consistent with the radical pair mechanism. CRY is widespread throughout biological systems and has been suggested as receptor for magnetic compass orientation in migratory birds. The present data establish the circadian clock of Drosophila as a model system for CRY-dependent magnetic sensitivity. Furthermore, given that CRY occurs in multiple tissues of Drosophila, including those potentially implicated in fly orientation, future studies may yield insights that could be applicable to the magnetic compass of migratory birds and even to potential magnetic field effects in humans. Magnetic fields influence endogenous clocks controlling the sleep–wake cycle of animals, but the underyling mechanisms are unclear. Birds that can do magnetic compass orientation also depend on light, and the blue-light photopigment cryptochrome was proposed to act as a navigational magnetosensor. Here we tested the role of cryptochrome as a light-dependent magnetosensor of the clock in the fruit fly Drosophila melanogaster. In wild-type flies we found that constant magnetic fields slowed down the speed of the clock in a dose-dependent manner—but only in the presence of blue light. In mutants lacking functional cryptochrome, the magnetic fields had no significant effects on the endogenous clock, whereas the effects were enhanced after overexpression of cryptochrome. Our data suggest that cryptochrome works as a magnetosensor in the endogenous clock when it is excited by blue light. Our work supports previous data showing that fruit flies need functional cryptochrome to perceive a magnetic field, demonstrating that the interaction of cryptochome and magnetic fields are not just for the birds. The molecular clock of the fruit fly is sensitive to magnetic fields in a manner dependent on blue light and the photopigment cryptochrome.
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Efimova O, Hore P. Evaluation of nuclear quadrupole interactions as a source of magnetic anisotropy in the radical pair model of the avian magnetic compass. Mol Phys 2009. [DOI: 10.1080/00268970902852624] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Rodgers CT, Hore PJ. Chemical magnetoreception in birds: the radical pair mechanism. Proc Natl Acad Sci U S A 2009; 106:353-60. [PMID: 19129499 PMCID: PMC2626707 DOI: 10.1073/pnas.0711968106] [Citation(s) in RCA: 314] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Indexed: 11/18/2022] Open
Abstract
Migratory birds travel vast distances each year, finding their way by various means, including a remarkable ability to perceive the Earth's magnetic field. Although it has been known for 40 years that birds possess a magnetic compass, avian magnetoreception is poorly understood at all levels from the primary biophysical detection events, signal transduction pathways and neurophysiology, to the processing of information in the brain. It has been proposed that the primary detector is a specialized ocular photoreceptor that plays host to magnetically sensitive photochemical reactions having radical pairs as fleeting intermediates. Here, we present a physical chemist's perspective on the "radical pair mechanism" of compass magnetoreception in birds. We outline the essential chemical requirements for detecting the direction of an Earth-strength approximately 50 microT magnetic field and comment on the likelihood that these might be satisfied in a biologically plausible receptor. Our survey concludes with a discussion of cryptochrome, the photoactive protein that has been put forward as the magnetoreceptor molecule.
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Affiliation(s)
- Christopher T. Rodgers
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QZ, United Kingdom; and
- Oxford Centre for Clinical Magnetic Resonance Research, Level 0, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
| | - P. J. Hore
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QZ, United Kingdom; and
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Diego-Rasilla FJ, Phillips JB. Magnetic Compass Orientation in Larval Iberian Green Frogs, Pelophylax Perezi. Ethology 2007. [DOI: 10.1111/j.1439-0310.2007.01334.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Wiltschko W, Ford H, Munro U, Winklhofer M, Wiltschko R. Magnetite-based magnetoreception: the effect of repeated pulsing on the orientation of migratory birds. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2007; 193:515-22. [PMID: 17318656 DOI: 10.1007/s00359-006-0207-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2006] [Revised: 12/27/2006] [Accepted: 12/28/2006] [Indexed: 11/27/2022]
Abstract
Previous studies have shown that a magnetic pulse affected the orientation of passerine migrants for a short period only: for about 3 days, the birds' headings were deflected eastward from their migratory direction, followed by a phase of disorientation, with the birds returning to their normal migratory direction after about 10 days. To analyze the processes involved in the fading of the pulse effect, migratory birds were subjected to a second, identical pulse 16 days after the first pulse, when the effect of that pulse had disappeared. This second pulse affected the birds' behavior in a different way: it caused an increase in the scatter of the birds' headings for 2 days, after which the birds showed normal migratory orientation again. These observations are at variance with the hypothesis that the magnetite-based receptor had been fully restored, but also with the hypothesis that the input of this receptor was ignored. They rather indicate dynamic processes, which include changes in the affected receptor, but at the same time cause the birds to weigh and rate the altered input differently. The bearing of these findings on the question of whether single domains or superparamagnetic particles are involved in the magnetite-based receptors is discussed.
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Affiliation(s)
- Wolfgang Wiltschko
- Fachbereich Biowissenschaften der J.W. Goethe-Universität, Siesmayerstrasse 70, D-60054, Frankfurt am Main, Germany.
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Wiltschko W, Munro U, Ford H, Wiltschko R. Bird navigation: what type of information does the magnetite-based receptor provide? Proc Biol Sci 2007; 273:2815-20. [PMID: 17015316 PMCID: PMC1664630 DOI: 10.1098/rspb.2006.3651] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Previous experiments have shown that a short, strong magnetic pulse caused migratory birds to change their headings from their normal migratory direction to an easterly direction in both spring and autumn. In order to analyse the nature of this pulse effect, we subjected migratory Australian silvereyes, Zosterops lateralis, to a magnetic pulse and tested their subsequent response under different magnetic conditions. In the local geomagnetic field, the birds preferred easterly headings as before, and when the horizontal component of the magnetic field was shifted 90 degrees anticlockwise, they altered their headings accordingly northwards. In a field with the vertical component inverted, the birds reversed their headings to westwards, indicating that their directional orientation was controlled by the normal inclination compass. These findings show that although the pulse strongly affects the magnetite particles, it leaves the functional mechanism of the magnetic compass intact. Thus, magnetite-based receptors seem to mediate magnetic 'map'-information used to determine position, and when affected by a pulse, they provide birds with false positional information that causes them to change their course.
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Affiliation(s)
- Wolfgang Wiltschko
- Fachbereich Biowissenschaften der J.W.Goethe-Universität, Siesmayerstrasse 70, 60054 Frankfurt am Main, Germany.
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Abstract
The vector of the geomagnetic field provides animals with directional information, while intensity and/or inclination provide them with positional information. For magnetoreception, two hypotheses are currently discussed: one proposing magnetite-based mechanisms, the other suggesting radical pair processes involving photopigments. Behavioral studies indicate that birds use both mechanisms: they responded to a short, strong magnetic pulse designed to change the magnetization of magnetite particles, while, at the same time, their orientation was found to be light-dependent and could be disrupted by high-frequency magnetic fields in the MHz range, which is diagnostic for radical pair processes. Details of these findings, together with electrophysiological and histological studies, suggest that, in birds, a radical pair mechanism located in the right eye provides directional information for a compass, while a magnetite-based mechanism located in the upper beak records magnetic intensity, thus providing positional information. The mechanisms of magnetoreception in other animals have not yet been analyzed in detail.
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Affiliation(s)
- Roswitha Wiltschko
- Fachbereich Biowissenschaften der J.W. Goethe-Universität Frankfurt am Main, Germany
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Abstract
Diverse animals can detect magnetic fields but little is known about how they do so. Three main hypotheses of magnetic field perception have been proposed. Electrosensitive marine fish might detect the Earth's field through electromagnetic induction, but direct evidence that induction underlies magnetoreception in such fish has not been obtained. Studies in other animals have provided evidence that is consistent with two other mechanisms: biogenic magnetite and chemical reactions that are modulated by weak magnetic fields. Despite recent advances, however, magnetoreceptors have not been identified with certainty in any animal, and the mode of transduction for the magnetic sense remains unknown.
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Affiliation(s)
- Sönke Johnsen
- Department of Biology, Duke University, Durham, North Carolina 27708, USA.
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Wiltschko W, Wiltschko R. Magnetic orientation and magnetoreception in birds and other animals. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2005; 191:675-93. [PMID: 15886990 DOI: 10.1007/s00359-005-0627-7] [Citation(s) in RCA: 291] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2004] [Revised: 03/04/2005] [Accepted: 03/05/2005] [Indexed: 10/25/2022]
Abstract
Animals use the geomagnetic field in many ways: the magnetic vector provides a compass; magnetic intensity and/or inclination play a role as a component of the navigational 'map', and magnetic conditions of certain regions act as 'sign posts' or triggers, eliciting specific responses. A magnetic compass is widespread among animals, magnetic navigation is indicated e.g. in birds, marine turtles and spiny lobsters and the use of magnetic 'sign posts' has been described for birds and marine turtles. For magnetoreception, two hypotheses are currently discussed, one proposing a chemical compass based on a radical pair mechanism, the other postulating processes involving magnetite particles. The available evidence suggests that birds use both mechanisms, with the radical pair mechanism in the right eye providing directional information and a magnetite-based mechanism in the upper beak providing information on position as component of the 'map'. Behavioral data from other animals indicate a light-dependent compass probably based on a radical pair mechanism in amphibians and a possibly magnetite-based mechanism in mammals. Histological and electrophysiological data suggest a magnetite-based mechanism in the nasal cavities of salmonid fish. Little is known about the parts of the brain where the respective information is processed.
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Affiliation(s)
- Wolfgang Wiltschko
- Zoologisches Institut der J.W.Goethe-Universität Frankfurt, Siesmayerstr. 70, 60054 Frankfurt am Main, Germany.
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Freake MJ, Phillips JB. Light-Dependent Shift in Bullfrog Tadpole Magnetic Compass Orientation: Evidence for a Common Magnetoreception Mechanism in Anuran and Urodele Amphibians. Ethology 2005. [DOI: 10.1111/j.1439-0310.2004.01067.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Timmel CR, Henbest KB. A study of spin chemistry in weak magnetic fields. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2004; 362:2573-2589. [PMID: 15539359 DOI: 10.1098/rsta.2004.1459] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This paper reviews the latest developments in the field of spin chemistry with a particular focus on the effects of weak static and/or oscillating magnetic fields (typically smaller than the average hyperfine coupling) on radical recombination reactions. Anisotropic magnetic field effects and their significance in the debate about potential mechanisms controlling magnetoreception in birds are discussed.
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Affiliation(s)
- Christiane R Timmel
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK.
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28
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Möller A, Sagasser S, Wiltschko W, Schierwater B. Retinal cryptochrome in a migratory passerine bird: a possible transducer for the avian magnetic compass. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2004; 91:585-8. [PMID: 15551029 DOI: 10.1007/s00114-004-0578-9] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2004] [Accepted: 09/26/2004] [Indexed: 11/25/2022]
Abstract
The currently discussed model of magnetoreception in birds proposes that the direction of the magnetic field is perceived by radical-pair processes in specialized photoreceptors, with cryptochromes suggested as potential candidate molecules mediating magnetic compass information. Behavioral studies have shown that magnetic compass orientation takes place in the eye and requires light from the blue-green part of the spectrum. Cryptochromes are known to absorb in the same spectral range. Because of this we searched for cryptochrome (CRY) in the retina of European robins, Erithacus rubecula, passerine birds that migrate at night. Here, we report three individually expressed cryptochromes, eCRY1a, eCRY1b, and eCRY2. While eCRY1a and eCRY2 are similar to the cryptochromes found in the retina of the domestic chicken, eCRY1b has a unique carboxy (C)-terminal. In light of the 'radical-pair' model, our findings support a potential role of cryptochromes as transducers for the perception of magnetic compass information in birds.
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Affiliation(s)
- Andrea Möller
- Zoologisches Institut, Fachbereich Biologie und Informatik, J.W. Goethe Universität, Siesmayerstrasse 70, 60323, Frankfurt am Main, Germany
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Wiltschko W, Möller A, Gesson M, Noll C, Wiltschko R. Light-dependent magnetoreception in birds: analysis of the behaviour under red light after pre-exposure to red light. ACTA ACUST UNITED AC 2004; 207:1193-202. [PMID: 14978060 DOI: 10.1242/jeb.00873] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In previous experiments, migratory birds had been disoriented under 635 nm red light, apparently unable to use their magnetic compass. The present study with European robins, Erithacus rubecula, confirms these findings for red light at the levels of 6 x 10(15) quanta s(-1) m(-2) and 43 x 10(15) quanta s(-1) m(-2), suggesting that the disorientation under red light was not caused by the test light being below the threshold for magnetoreception. However, pre-exposure to red light for 1 h immediately before the critical tests under red light of 6-7 x 10(15) quanta s(-1) m(-2) enabled robins to orient in their seasonally appropriate migratory direction in spring as well as in autumn. Pre-exposure to darkness, by contrast, failed to induce orientation under red light. Under green light of 7 x 10(15) quanta s(-1) m(-2), the birds were oriented in their migratory orientation after both types of pre-exposure. These findings suggest that the newly gained ability to orient under red light might be based on learning to interpret a novel pattern of activation of the magnetoreceptors and hence may represent a parallel to the previously described enlargement of the functional window to new magnetic intensities. Mechanisms involving two types of spectral mechanisms with different absorbance maxima and their possible interactions are discussed.
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Affiliation(s)
- Wolfgang Wiltschko
- Fachbereich Biologie und Informatik, Zoologie, J. W. Goethe-Universität Frankfurt, Siesmayerstrasse 70, D-60054 Frankfurt am Main, Germany.
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Wiltschko W, Munro U, Ford H, Wiltschko R. Magnetic orientation in birds: non-compass responses under monochromatic light of increased intensity. Proc Biol Sci 2003; 270:2133-40. [PMID: 14561276 PMCID: PMC1691490 DOI: 10.1098/rspb.2003.2476] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Migratory Australian silvereyes (Zosterops lateralis) were tested under monochromatic light at wavelengths of 424 nm blue and 565 nm green. At a low light level of 7 x 10(15) quanta m(-2) s(-1) in the local geomagnetic field, the birds preferred their seasonally appropriate southern migratory direction under both wavelengths. Their reversal of headings when the vertical component of the magnetic field was inverted indicated normal use of the avian inclination compass. A higher light intensity of 43 x 10(15) quanta m(-2) s(-1), however, caused a fundamental change in behaviour: under bright blue, the silvereyes showed an axial tendency along the east-west axis; under bright green, they showed a unimodal preference of a west-northwesterly direction that followed a shift in magnetic north, but was not reversed by inverting the vertical component of the magnetic field. Hence it is not based on the inclination compass. The change in behaviour at higher light intensities suggests a complex interaction between at least two receptors. The polar nature of the response under bright green cannot be explained by the current models of light-dependent magnetoreception and will lead to new considerations on these receptive processes.
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Affiliation(s)
- Wolfgang Wiltschko
- Zoologisches Institut der J.W. Goethe-Universität Frankfurt a.M., Siesmayerstrasse 70, D-60054 Frankfurt a.M., Germany.
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Phillips JB, Borland SC, Freake MJ, Brassart J, Kirschvink JL. `Fixed-axis' magnetic orientation by an amphibian: non-shoreward-directed compass orientation, misdirected homing or positioning a magnetite-based map detector in a consistent alignment relative to the magnetic field? J Exp Biol 2002; 205:3903-14. [PMID: 12432012 DOI: 10.1242/jeb.205.24.3903] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYExperiments were carried out to investigate the earlier prediction that prolonged exposure to long-wavelength (>500 nm) light would eliminate homing orientation by male Eastern red-spotted newts Notophthalmus viridescens. As in previous experiments, controls held in outdoor tanks under natural lighting conditions and tested in a visually uniform indoor arena under full-spectrum light were homeward oriented. As predicted, however,newts held under long-wavelength light and tested under either full-spectrum or long-wavelength light (>500 nm) failed to show consistent homeward orientation. The newts also did not orient with respect to the shore directions in the outdoor tanks in which they were held prior to testing. Unexpectedly, however, the newts exhibited bimodal orientation along a more-or-less `fixed' north-northeast—south-southwest magnetic axis. The orientation exhibited by newts tested under full-spectrum light was indistinguishable from that of newts tested under long-wavelength light,although these two wavelength conditions have previously been shown to differentially affect both shoreward compass orientation and homing orientation. To investigate the possibility that the `fixed-axis' response of the newts was mediated by a magnetoreception mechanism involving single-domain particles of magnetite, natural remanent magnetism (NRM) was measured from a subset of the newts. The distribution of NRM alignments with respect to the head—body axis of the newts was indistinguishable from random. Furthermore, there was no consistent relationship between the NRM of individual newts and their directional response in the overall sample. However, under full-spectrum, but not long-wavelength, light, the alignment of the NRM when the newts reached the 20 cm radius criterion circle in the indoor testing arena (estimated by adding the NRM alignment measured from each newt to its magnetic bearing) was non-randomly distributed. These findings are consistent with the earlier suggestion that homing newts use the light-dependent magnetic compass to align a magnetite-based `map detector'when obtaining the precise measurements necessary to derive map information from the magnetic field. However, aligning the putative map detector does not explain the fixed-axis response of newts tested under long-wavelength light. Preliminary evidence suggests that, in the absence of reliable directional information from the magnetic compass (caused by the 90° rotation of the response of the magnetic compass under long-wavelength light), newts may resort to a systematic sampling strategy to identify alignment(s) of the map detector that yields reliable magnetic field measurements.
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Affiliation(s)
- John B Phillips
- Biology Department, Virginia Tech University, Blacksburg 24061, USA.
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Muheim R, Bäckman J, Akesson S. Magnetic compass orientation in European robins is dependent on both wavelength and intensity of light. J Exp Biol 2002; 205:3845-56. [PMID: 12432008 DOI: 10.1242/jeb.205.24.3845] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYMagnetic compass orientation in birds has been shown to be light dependent. Results from behavioural studies indicate that magnetoreception capabilities are disrupted under light of peak wavelengths longer than 565 nm, and shifts in orientation have been observed at higher light intensities(43-44×1015 quanta s-1 m-2). To investigate further the function of the avian magnetic compass with respect to wavelength and intensity of light, we carried out orientation cage experiments with juvenile European robins, caught during their first autumn migration,exposed to light of 560.5 nm (green), 567.5 nm (green-yellow) and 617 nm (red)wavelengths at three different intensities (1 mW m-2, 5 mW m-2 and 10 mW m-2). We used monochromatic light of a narrow wavelength range (half bandwidth of 9-11 nm, compared with half bandwidths ranging between 30 nm and 70 nm used in other studies) and were thereby able to examine the magnetoreception mechanism in the expected transition zone between oriented and disoriented behaviour around 565 nm in more detail. We show (1) that European robins show seasonally appropriate migratory directions under 560.5 nm light, (2) that they are completely disoriented under 567.5 nm light under a broad range of intensities, (3) that they are able to orient under 617 nm light of lower intensities, although into a direction shifted relative to the expected migratory one, and (4) that magnetoreception is intensity dependent, leading to disorientation under higher intensities. Our results support the hypothesis that birds possess a light-dependent magnetoreception system based on magnetically sensitive,antagonistically interacting spectral mechanisms, with at least one high-sensitive short-wavelength mechanism and one low-sensitive long-wavelength mechanism.
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Affiliation(s)
- Rachel Muheim
- Bird Migration Group, Department of Animal Ecology, Lund University, Ecology Building, Sweden.
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Wiltschko W, Wiltschko R. Light-dependent magnetoreception in birds: the behaviour of European robins,Erithacus rubecula, under monochromatic light of various wavelengths and intensities. J Exp Biol 2001; 204:3295-302. [PMID: 11606603 DOI: 10.1242/jeb.204.19.3295] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYTo investigate how magnetoreception is affected by the wavelength and intensity of light, we tested European robins, Erithacus rubecula, under monochromatic lights of various wavelengths at two intensities using oriented behaviour as an indicator of whether the birds could derive directional information from the geomagnetic field. At a quantal flux of 7×1015 quanta s–1 m–2, the birds were well oriented in their migratory direction east of North under 424 nm blue, 510 nm turquoise and 565 nm green light, whereas they were disoriented under 590 nm yellow light. Increasing the intensity of light at the same wavelengths more than sixfold to 43×1015 quanta s–1 m–2 resulted in a change in behaviour: under bright blue and green light, the birds now showed a preference for the East–West axis, with the majority of headings at the western end; under bright turquoise light, they oriented unimodally towards a direction slightly west of North. Under bright yellow light, the birds continued to be disoriented.These findings suggest a rather complex relationship between the receptors involved in magnetoreception. Magnetoreception appears to follow rules that are different from those of vision, suggesting that light-dependent magnetoreception may involve receptors and neuronal pathways of its own.
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Affiliation(s)
- W Wiltschko
- Fachbereich Biologie, Zoologie, J. W. Goethe-Universität Frankfurt a.M., Siesmayerstrasse 70, D-60054 Frankfurt a.M., Germany.
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34
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Timmel C, Cintolesi F, Brocklehurst B, Hore P. Model calculations of magnetic field effects on the recombination reactions of radicals with anisotropic hyperfine interactions. Chem Phys Lett 2001. [DOI: 10.1016/s0009-2614(00)01436-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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35
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Stass D, Woodward J, Timmel C, Hore P, McLauchlan K. Radiofrequency magnetic field effects on chemical reaction yields. Chem Phys Lett 2000. [DOI: 10.1016/s0009-2614(00)00980-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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36
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Weaver JC, Vaughan TE, Astumian RD. Biological sensing of small field differences by magnetically sensitive chemical reactions. Nature 2000; 405:707-9. [PMID: 10864331 DOI: 10.1038/35015128] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
There is evidence that animals can detect small changes in the Earth's magnetic field by two distinct mechanisms, one using the mineral magnetite as the primary sensor and one using magnetically sensitive chemical reactions. Magnetite responds by physically twisting, or even reorienting the whole organism in the case of some bacteria, but the magnetic dipoles of individual molecules are too small to respond in the same way. Here we assess whether reactions whose rates are affected by the orientation of reactants in magnetic fields could form the basis of a biological compass. We use a general model, incorporating biological components and design criteria, to calculate realistic constraints for such a compass. This model compares a chemical signal produced owing to magnetic field effects with stochastic noise and with changes due to physiological temperature variation. Our analysis shows that a chemically based biological compass is feasible with its size, for any given detection limit, being dependent on the magnetic sensitivity of the rate constant of the chemical reaction.
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Affiliation(s)
- J C Weaver
- Harvard-M.I.T. Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge 02139, USA.
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37
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Rappl R, Wiltschko R, Weindler P, Berthold P, Wiltschko W. Orientation Behavior of Garden Warblers (Sylvia borin) Under Monochromatic Light of Various Wavelengths. ACTA ACUST UNITED AC 2000. [DOI: 10.1093/auk/117.1.256] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Ralf Rappl
- Fachbereich Biologie, Zoologie der Johann Wolfgang Goethe-Universität, Siesmayerstraße 70, D-60054 Frankfurt am Main, Germany
| | - Roswitha Wiltschko
- Fachbereich Biologie, Zoologie der Johann Wolfgang Goethe-Universität, Siesmayerstraße 70, D-60054 Frankfurt am Main, Germany
| | - Peter Weindler
- Fachbereich Biologie, Zoologie der Johann Wolfgang Goethe-Universität, Siesmayerstraße 70, D-60054 Frankfurt am Main, Germany
| | - Peter Berthold
- Forschungsstelle für Ornithologie der Max-Planck-Gesellschaft, Vogelwarte Radolfzell, D-78315 Möggingen, Germany
| | - Wolfgang Wiltschko
- Fachbereich Biologie, Zoologie der Johann Wolfgang Goethe-Universität, Siesmayerstraße 70, D-60054 Frankfurt am Main, Germany
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Abstract
This paper postulates five experiments that may be used to characterize the nature of the transduction step in which a magnetic or electric field is converted into a biological signal. Each of the five experiments is formulated as a refutable hypothesis in such a manner that rejection of the hypothesis will provide information about the transduction process and an associated confidence level for evaluating each experiment. The proposed hypotheses are formulated to provide inferences about the mode of interaction (magnetic field or induced electric field transduction), spatial distribution of the detector elements in the biological system, and the timescale of the transductive step.
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Affiliation(s)
- S Engström
- Biomedical Sciences, University of California, Riverside, California.
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Thoss F, Bartsch B, Tellschaft D, Thoss M. Periodic inversion of the vertical component of the earth's magnetic field influences fluctuations of visual sensitivity in humans. Bioelectromagnetics 1999; 20:459-61. [PMID: 10495312 DOI: 10.1002/(sici)1521-186x(199910)20:7<459::aid-bem8>3.0.co;2-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
According to theoretical considerations, the magnetic field of the earth could influence the first steps of light-induced changes in ocular photopigment, an effect that is thought to underlie the magnetic orientation of some animals. To find out whether man could be influenced in this way, we have tested the effect of an artificial fluctuation in the direction of the earth's magnetic field on oscillations of the visual sensitivity in 27 healthy subjects. The resultant spectra show a significant influence of the field fluctuations, indicating that man is sensitive to changes in the direction of the earth's magnetic field.
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Affiliation(s)
- F Thoss
- Carl Ludwig Institute of Physiology of the University of Leipzig, Leipzig, Germany.
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40
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Timmel C, Till U, Brocklehurst B, Mclauchlan K, Hore P. Effects of weak magnetic fields on free radical recombination reactions. Mol Phys 1998. [DOI: 10.1080/00268979809483134] [Citation(s) in RCA: 195] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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41
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43
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Weaver JC, Astumian RD. Estimates for ELF effects: noise-based thresholds and the number of experimental conditions required for empirical searches. Bioelectromagnetics 1992; Suppl 1:119-38. [PMID: 1285708 DOI: 10.1002/bem.2250130712] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Interactions between physical fields and biological systems present difficult conceptual problems. Complete biological systems, even isolated cells, are exceedingly complex. This argues against the pursuit of theoretical models, with the possible consequence that only experimental studies should be considered. In contrast, electromagnetic fields are well understood. Further, some subsystems of cells (viz. cell membranes) can be reasonably represented by physical models. This argues for the pursuit of theoretical models which quantitatively describe interactions of electromagnetic fields with that subsystem. Here we consider the hypothesis that electric fields, not magnetic fields, are the source of interactions, From this it follows that the cell membrane is a relevant subsystem, as the membrane is much more resistive than the intra- or extracellular regions. A general class of interactions is considered: electroconformational changes associated with the membrane. Expected results of such as approach include the dependence of the interaction on key parameters (e.g., cell size, field magnitude, frequency, and exposure time), constraints on threshold exposure conditions, and insight into how experiments might be designed. Further, because it is well established that strong and moderate electric fields interact significantly with cells, estimates of the extrapolated interaction for weaker fields can be sought. By employing signal-to-noise (S/N) ratio criteria, theoretical models can also be used to estimate threshold magnitudes. These estimates are particularly relevant to in vitro conditions, for which most biologically generated background fields are absent. Finally, we argue that if theoretical model predictions are unavailable to guide the selection of experimental conditions, an overwhelmingly large number of different conditions will be needed to find, establish, and characterize bioelectromagnetic effects in an empirical search. This is contrasted with well-established chemical dosimetry, which is much simpler. Because of the large number of possible electromagnetic field conditions, we also conclude that in vitro studies, rather than in vivo studies, should be emphasized in studies aimed at discovering and characterizing mechanisms for bioelectromagnetic effects.
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Affiliation(s)
- J C Weaver
- Massachusetts Institute of Technology, Harvard-MIT Division of Health Sciences and Technology, Cambridge 02139
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44
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Phillips J, Borland S. Wavelength specific effects of light on magnetic compass orientation of the eastern red-spotted newtNotophthalmus viridescens. ETHOL ECOL EVOL 1992. [DOI: 10.1080/08927014.1992.9525348] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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45
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Magnetic field effects on activity and ageing in honeybees. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1989. [DOI: 10.1007/bf00610436] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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46
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Kirschvink JL. Magnetite biomineralization and geomagnetic sensitivity in higher animals: an update and recommendations for future study. Bioelectromagnetics 1989; 10:239-59. [PMID: 2665750 DOI: 10.1002/bem.2250100304] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Magnetite, the only known biogenic material with ferromagnetic properties, has been identified as a biochemical precipitate in three of the five kingdoms of living organisms, with a fossil record that now extends back nearly 2 billion years. In the magnetotactic bacteria, protoctists, and fish, single-domain crystals of magnetite are arranged in membrane-bound linear structures called magnetosomes, which function as biological bar magnets. Magnetosomes in all three of these groups bear an overall structural similarity to each other, which includes alignment of the individual crystallographic [111] directions parallel to the long axis. Although the magnetosomes represent only a small volume fraction in higher organisms, enough of these highly energetic structures are present to provide sensitivity to extremely small fluctuations and gradients in the background geomagnetic field. Previous experiments with elasmobranch fish are reexamined to test the hypothesis that gradients played a role in their successful geomagnetic conditioning, and a variety of four-turn coil designs are considered that could be used to test the various hypotheses proposed for them.
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Affiliation(s)
- J L Kirschvink
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena 91125
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Wallraff HG. [Navigation by means of an olfactory map and a sun compass: the homing ability of pigeons]. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 1988; 75:380-92. [PMID: 3065647 DOI: 10.1007/bf00377814] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Pigeon homing, investigated as a paradigmatic example of bird navigation, appears to be based on two mechanisms of orientation whose functions correspond to those of map and compass. Tasks of the latter are usually accomplished by a sun compass, taking into account the sun's movement and time of day. Under overcast skies, the magnetic field of the earth may be used for compass orientation. The "map" part of the system, responsible for site localization, makes use of olfactory perception of atmospheric trace compounds, which must be concluded to contain positional information in unfamiliar areas up to several hundreds of kilometers from home.
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Affiliation(s)
- H G Wallraff
- Max-Planck-Institut für Verhaltensphysiologie, Seewiesen Post Starnberg
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48
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Korall H, Leucht T, Martin H. Bursts of magnetic fields induce jumps of misdirection in bees by a mechanism of magnetic resonance. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1988. [DOI: 10.1007/bf00606116] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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49
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Leucht T. Magnetic effects on tail-fin melanophores of Xenopus laevis tadpoles in vitro. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 1987; 74:441-3. [PMID: 3683589 DOI: 10.1007/bf00446101] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- T Leucht
- Zoologisches Institut (II) der Universität, Wruzburg
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