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Merlin C. Insect magnetoreception: a Cry for mechanistic insights. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2023; 209:785-792. [PMID: 37184693 DOI: 10.1007/s00359-023-01636-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/24/2023] [Accepted: 05/04/2023] [Indexed: 05/16/2023]
Abstract
Migratory animals can detect and use the Earth's magnetic field for orientation and navigation, sometimes over distances spanning thousands of kilometers. How they do so remains, however, one of the greatest mysteries in all sensory biology. Here, the author reviews the progress made to understand the molecular bases of the animal magnetic sense focusing on insect species, the only species in which genetic studies have so far been possible. The central hypothesis in the field posits that magnetically sensitive radical pairs formed by photoexcitation of cryptochrome proteins are key to animal magnetoreception. The author provides an overview of our current state of knowledge for the involvement of insect light-sensitive type I and light-insensitive type II cryptochromes in this enigmatic sense, and highlights some of the unanswered questions to gain a comprehensive understanding of magnetoreception at the organismal level.
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Affiliation(s)
- Christine Merlin
- Center for Biological Clock Research and Department of Biology, Texas A&M University, College Station, TX, 77845, USA.
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Phillips J, Muheim R, Painter M, Raines J, Anderson C, Landler L, Dommer D, Raines A, Deutschlander M, Whitehead J, Fitzpatrick NE, Youmans P, Borland C, Sloan K, McKenna K. Why is it so difficult to study magnetic compass orientation in murine rodents? J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2022; 208:197-212. [PMID: 35094127 DOI: 10.1007/s00359-021-01532-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 11/30/2021] [Accepted: 12/03/2021] [Indexed: 01/21/2023]
Abstract
A magnetic compass sense has been demonstrated in all major classes of vertebrates, as well as in many invertebrates. In mammals, controlled laboratory studies of mice have provided evidence for a robust magnetic compass that is comparable to, or exceeds, the performance of that in other animals. Nevertheless, the vast majority of laboratory studies of spatial behavior and cognition in murine rodents have failed to produce evidence of sensitivity to magnetic cues. Given the central role that a magnetic compass sense plays in the spatial ecology and cognition of non-mammalian vertebrates, and the potential utility that a global/universal reference frame derived from the magnetic field would have in mammals, the question of why responses to magnetic cues have been so difficult to demonstrate reliably is of considerable importance. In this paper, we review evidence that the magnetic compass of murine rodents shares a number of properties with light-dependent compasses in a wide variety of other animals generally believed to be mediated by a radical pair mechanism (RPM) or related quantum process. Consistent with the RPM, we summarize both published and previously unpublished findings suggesting that the murine rodent compass is sensitive to low-level radio frequency (RF) fields. Finally, we argue that the presence of anthropogenic RF fields in laboratory settings, may be an important source of variability in responses of murine rodents to magnetic cues.
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Affiliation(s)
- John Phillips
- Dept of Biological Sciences, Virginia Tech, Blacksburg, VA, 24061-0406, USA.
| | - Rachel Muheim
- Dept of Biology, Lund University, Biology Building, 223 62, Lund, Sweden
| | - Michael Painter
- Dept of Biology, Barry University, 11300 NE 2nd Ave, Miami, FL, 33161, USA
| | - Jenny Raines
- University of Virginia, 409 Lane Road, Charlottesville, VA, 22908, USA
| | - Chris Anderson
- Electrical Engineering Dept, US Naval Academy, 105 Maryland Ave, Annapolis, MD, 21402, USA
| | - Lukas Landler
- Institute of Zoology, University of Natural Resources and Life Sciences (BOKU), Gregor-Mendel-Straße 33/I, 1180, Vienna, Austria
| | - Dave Dommer
- University of Mount Olive, 5001 South Miami Boulevard, Durham, NC, 27703, USA
| | - Adam Raines
- Dept of Biological Sciences, Virginia Tech, Blacksburg, VA, 24061-0406, USA
| | - Mark Deutschlander
- Dept of Biology, Hobart and William Smith Colleges, 300 Pulteney St., Geneva, NY, 14456, USA
| | - John Whitehead
- Dept of Biological Sciences, Virginia Tech, Blacksburg, VA, 24061-0406, USA
| | | | - Paul Youmans
- Dept of Biological Sciences, Virginia Tech, Blacksburg, VA, 24061-0406, USA
| | - Chris Borland
- Civic Champs, 642 N. Madison St., Suite 116, Bloomington, IN, 47404, USA
| | - Kelly Sloan
- Sanibel Captiva Conservation Foundation, 3333 Sanibel Captiva Rd, PO Box 839, Sanibel, FL, 33957, USA
| | - Kaitlyn McKenna
- Dept of Biological Sciences, Virginia Tech, Blacksburg, VA, 24061-0406, USA
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Leberecht B, Kobylkov D, Karwinkel T, Döge S, Burnus L, Wong SY, Apte S, Haase K, Musielak I, Chetverikova R, Dautaj G, Bassetto M, Winklhofer M, Hore PJ, Mouritsen H. Broadband 75-85 MHz radiofrequency fields disrupt magnetic compass orientation in night-migratory songbirds consistent with a flavin-based radical pair magnetoreceptor. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2022. [PMID: 35019998 DOI: 10.1007/s00359-021-01537-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 12/15/2021] [Accepted: 12/17/2021] [Indexed: 12/20/2022]
Abstract
The light-dependent magnetic compass sense of night-migratory songbirds can be disrupted by weak radiofrequency fields. This finding supports a quantum mechanical, radical-pair-based mechanism of magnetoreception as observed for isolated cryptochrome 4, a protein found in birds’ retinas. The exact identity of the magnetically sensitive radicals in cryptochrome is uncertain in vivo, but their formation seems to require a bound flavin adenine dinucleotide chromophore and a chain of four tryptophan residues within the protein. Resulting from the hyperfine interactions of nuclear spins with the unpaired electrons, the sensitivity of the radicals to radiofrequency magnetic fields depends strongly on the number of magnetic nuclei (hydrogen and nitrogen atoms) they contain. Quantum-chemical calculations suggested that electromagnetic noise in the frequency range 75–85 MHz could give information about the identity of the radicals involved. Here, we show that broadband 75–85 MHz radiofrequency fields prevent a night-migratory songbird from using its magnetic compass in behavioural experiments. These results indicate that at least one of the components of the radical pair involved in the sensory process of avian magnetoreception must contain a substantial number of strong hyperfine interactions as would be the case if a flavin–tryptophan radical pair were the magnetic sensor.
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Sales MVG, Lima BS, Acosta-Avalos D. U-turn time and velocity dependence on the wavelength of light: multicellular magnetotactic prokaryotes of different sizes behave differently. Eur Biophys J 2020; 49:633-642. [PMID: 33094363 DOI: 10.1007/s00249-020-01472-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 08/17/2020] [Accepted: 10/19/2020] [Indexed: 06/11/2023]
Abstract
'Candidatus Magnetoglobus multicellularis' is a multicellular magnetotactic prokaryote found in the Araruama lagoon in Rio de Janeiro, Brazil. This microorganism shows a photokinesis that depends on the incident light wavelength, but that dependence can be canceled by the presence of radio-frequency (RF) electromagnetic fields. The present manuscript has as its aim to study the effect of light wavelength and RF fields on the U-turn time of 'Candidatus Magnetoglobus multicellularis', a behavior more related to magnetotaxis. As the experiments were performed during the night, the microorganisms were greater in size than normal, indicating that they were in the process of division. Our results show that when normal in size, the microorganism's U-turn time is modified by the light wavelength (lower for blue light than for green and red light), but RF fields do not affect that U-turn time dependence on the light wavelength. For the microorganism in the process of division, we describe for the first time how the photokinesis and U-turn time dependence on the light wavelength disappear. It is proposed that methyl-accepting chemotaxis proteins are involved in that light wavelength dependence for the U-turn time, but still more studies are necessary to understand how RF fields cancel the photokinesis light wavelength dependence, but do not affect the dependence of the U-turn time.
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Affiliation(s)
| | - Beatriz Silva Lima
- Centro Brasileiro de Pesquisas Físicas, CBPF, Rua Xavier Sigaud 150, Urca, Rio de Janeiro, RJ, 22290-180, Brazil
| | - Daniel Acosta-Avalos
- Centro Brasileiro de Pesquisas Físicas, CBPF, Rua Xavier Sigaud 150, Urca, Rio de Janeiro, RJ, 22290-180, Brazil.
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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. Biol Cybern 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] [What about the content of this article? (0)] [Affiliation(s)] [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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Wiltschko R, Gehring D, Denzau S, Nießner C, Wiltschko W. Magnetoreception in birds: II. Behavioural experiments concerning the cryptochrome cycle. ACTA ACUST UNITED AC 2015; 217:4225-8. [PMID: 25472973 PMCID: PMC4254397 DOI: 10.1242/jeb.110981] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Behavioural tests of the magnetic compass of birds and corresponding immunohistological studies on the activation of retinal cryptochrome 1a, the putative receptor molecule, showed oriented behaviour and activated Cry1a under 373 nm UV, 424 nm blue, 502 nm turquoise and 565 nm green light, although the last wavelength does not allow the first step of photoreduction of cryptochrome to the semiquinone form. The tested birds had been kept under ‘white’ light before, hence we suggested that there was a supply of semiquinone present at the beginning of the exposure to green light that could be further reduced and then re-oxidized. To test the hypothesis in behavioural experiments, we tested robins, Erithacus rubecula, under various wavelengths (1) after 1 h pre-exposure to total darkness and (2) after 1 h pre-exposure to the same light as used in the test. The birds were oriented under blue and turquoise light, where the full cryptochrome cycle can run, but not under green light. This finding is in agreement with the hypothesis. Orientation under green light appears to be a transient phenomenon until the supply of semiquinone is depleted.
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Affiliation(s)
- Roswitha Wiltschko
- Goethe-Universität Frankfurt, FB Biowissenschaften, Max-von-Laue-Straße 13, D-60438 Frankfurt am Main, Germany
| | - Dennis Gehring
- Goethe-Universität Frankfurt, FB Biowissenschaften, Max-von-Laue-Straße 13, D-60438 Frankfurt am Main, Germany
| | - Susanne Denzau
- Goethe-Universität Frankfurt, FB Biowissenschaften, Max-von-Laue-Straße 13, D-60438 Frankfurt am Main, Germany
| | - Christine Nießner
- Goethe-Universität Frankfurt, FB Biowissenschaften, Max-von-Laue-Straße 13, D-60438 Frankfurt am Main, Germany
| | - Wolfgang Wiltschko
- Goethe-Universität Frankfurt, FB Biowissenschaften, Max-von-Laue-Straße 13, D-60438 Frankfurt am Main, Germany
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