1
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Muheim R, Phillips JB. Effects of low-level RF fields reveal complex pattern of magnetic input to the avian magnetic compass. Sci Rep 2023; 13:19970. [PMID: 37968316 PMCID: PMC10651899 DOI: 10.1038/s41598-023-46547-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 11/02/2023] [Indexed: 11/17/2023] Open
Abstract
The avian magnetic compass can be disrupted by weak narrow-band and broadband radio-frequency (RF) fields in the lower MHz range. However, it is unclear whether disruption of the magnetic compass results from the elimination of the perception pattern produced by the magnetic field or from qualitative changes that make the pattern unrecognizable. We show that zebra finches trained in a 4-arm maze to orient relative to the magnetic field are disoriented when tested in the presence of low-level (~ 10 nT) Larmor-frequency RF fields. However, they are able to orient when tested in such RF fields if trained under this condition, indicating that the RF field alters, but does not eliminate, the magnetic input. Larmor-frequency RF fields of higher intensities, with or without harmonics, dramatically alter the magnetic compass response. In contrast, exposure to broadband RF fields in training, in testing, or in both training and testing eliminates magnetic compass information. These findings demonstrate that low-level RF fields at intensities found in many laboratory and field experiments may have very different effects on the perception of the magnetic field in birds, depending on the type and intensity of the RF field, and the birds' familiarity with the RF-generated pattern.
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Affiliation(s)
- Rachel Muheim
- Department of Biology, Lund University, Biology Building, 223 62, Lund, Sweden.
| | - John B Phillips
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, 24061-0406, USA
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2
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Zhang L, Malkemper EP. Cryptochromes in mammals: a magnetoreception misconception? Front Physiol 2023; 14:1250798. [PMID: 37670767 PMCID: PMC10475740 DOI: 10.3389/fphys.2023.1250798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 08/01/2023] [Indexed: 09/07/2023] Open
Abstract
Cryptochromes are flavoproteins related to photolyases that are widespread throughout the plant and animal kingdom. They govern blue light-dependent growth in plants, control circadian rhythms in a light-dependent manner in invertebrates, and play a central part in the circadian clock in vertebrates. In addition, cryptochromes might function as receptors that allow animals to sense the Earth's magnetic field. As cryptochromes are also present in mammals including humans, the possibility of a magnetosensitive protein is exciting. Here we attempt to provide a concise overview of cryptochromes in mammals. We briefly review their canonical role in the circadian rhythm from the molecular level to physiology, behaviour and diseases. We then discuss their disputed light sensitivity and proposed role in the magnetic sense in mammals, providing three mechanistic hypotheses. Specifically, mammalian cryptochromes could form light-induced radical pairs in particular cellular milieus, act as magnetoreceptors in darkness, or as secondary players in a magnetoreception signalling cascade. Future research can test these hypotheses to investigate if the role of mammalian cryptochromes extends beyond the circadian clock.
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Affiliation(s)
| | - E. Pascal Malkemper
- Max Planck Research Group Neurobiology of Magnetoreception, Max Planck Institute for Neurobiology of Behavior—caesar, Bonn, Germany
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3
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Wong SY, Benjamin P, Hore PJ. Magnetic field effects on radical pair reactions: estimation of B1/2 for flavin-tryptophan radical pairs in cryptochromes. Phys Chem Chem Phys 2023; 25:975-982. [PMID: 36519379 PMCID: PMC9811481 DOI: 10.1039/d2cp03793a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Magnetic field effects on the yields of radical pair reactions are often characterised by the "half-field" parameter, B1/2, which encodes useful information on spin relaxation, radical recombination kinetics and electron-electron couplings as well as electron-nuclear hyperfine interactions. Here we use a variety of spin dynamics simulation methods to estimate the hyperfine-only values of B1/2 for the flavin-tryptophan radical pair, [FAD˙- TrpH˙+], thought to be the detector in the magnetic compass sense of migratory songbirds. The main findings are: (a) in the absence of fast recombination and spin relaxation, [FAD˙- TrpH˙+] radical pairs in solution and in the putative magnetoreceptor protein, cryptochrome, have B1/2 ≈ 1.89 mT and 2.46 mT, respectively. (b) The widely used expression for B1/2 due to Weller et al. (Chem. Phys. Lett, 1983, 96, 24-27) is only applicable to small, short-lived (∼5 ns), rapidly tumbling radical pairs in solution, and is quantitatively unreliable in the context of magnetoreception. (c) In the absence of molecular tumbling, the low-field effect for [FAD˙- TrpH˙+] is predicted to be abolished by the anisotropic components of the hyperfine interactions. Armed with the 2.46 mT "base value" for cryptochrome, measurements of B1/2 can be used to understand the impact of spin relaxation on its performance as a magnetic compass sensor.
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Affiliation(s)
- Siu Ying Wong
- Institut für Physik, Carl-von-Ossietzky Universität OldenburgOldenburg 26111Germany
| | - Philip Benjamin
- Department of Chemistry, University of OxfordOxfordOX1 3QZUK
| | - P. J. Hore
- Department of Chemistry, University of OxfordOxfordOX1 3QZUK
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4
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Direct experimental observation of blue-light-induced conformational change and intermolecular interactions of cryptochrome. Commun Biol 2022; 5:1103. [PMID: 36257983 PMCID: PMC9579160 DOI: 10.1038/s42003-022-04054-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 09/30/2022] [Indexed: 11/30/2022] Open
Abstract
Cryptochromes are blue light receptors that mediate circadian rhythm and magnetic sensing in various organisms. A typical cryptochrome consists of a conserved photolyase homology region domain and a varying carboxyl-terminal extension across species. The structure of the flexible carboxyl-terminal extension and how carboxyl-terminal extension participates in cryptochrome’s signaling function remain mostly unknown. In this study, we uncover the potential missing link between carboxyl-terminal extension conformational changes and downstream signaling functions. Specifically, we discover that the blue-light induced opening of carboxyl-terminal extension in C. reinhardtii animal-like cryptochrome can structurally facilitate its interaction with Rhythm Of Chloroplast 15, a circadian-clock-related protein. Our finding is made possible by two technical advances. Using single-molecule Förster resonance energy transfer technique, we directly observe the displacement of carboxyl-terminal extension by about 15 Å upon blue light excitation. Combining structure prediction and solution X-ray scattering methods, we propose plausible structures of full-length cryptochrome under dark and lit conditions. The structures provide molecular basis for light active conformational changes of cryptochrome and downstream regulatory functions. Refined structures, protein-docking analysis and single molecule assays provides insights into light-induced conformational changes in the cryptochrome CraCRY.
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5
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Zhang Y, Zeng L, Wei Y, Zhang M, Pan W, Sword GA, Yang F, Chen F, Wan G. Reliable reference genes for gene expression analyses under the hypomagnetic field in a migratory insect. Front Physiol 2022; 13:954228. [PMID: 36003646 PMCID: PMC9393789 DOI: 10.3389/fphys.2022.954228] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 07/07/2022] [Indexed: 11/13/2022] Open
Abstract
Manipulating the hypomagnetic field (HMF), which is the absence or significant weakening (<5 μT) of the geomagnetic field (GMF), offers a unique tool to investigate magnetic field effects on organismal physiology, development, behavior and life history. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) has been utilized to study changes in gene expression associated with exposure to the HMF. However, selecting appropriate reference genes (RGs) with confirmed stable expression across environments for RT-qPCR is often underappreciated. Using three algorithms (BestKeeper, NormFinder, and GeNorm), we investigated the expression stability of eight candidate RGs when exposed to the HMF condition versus local GMF during developmental from juveniles to adults in the migratory insect pest, the brown planthopper Nilaparvata lugens. During the nymphal stage, RPL5 & α-TUB1, EF1-α & ARF1, RPL5 & AK, EF1-α & RPL5, and ARF1 & AK were suggested as the most stable RG sets in the 1st to 5th instars, respectively. For 1- to 3-day-old adults, AK & ARF1, AK & α-TUB1, AK & ARF1 and EF1-α & RPL5, AK & α-TUB1, AK & EF1-α were the optimal RG sets for macropterous and brachypterous females, respectively. ACT1 & RPL5, RPL5 & EF1-α, α-TUB1 & ACT1 and EF1-α & RPL5, ARF1 & ACT1, ACT1 & ARF1 were the optimal RG sets for macropterous and brachypterous males, respectively. These results will facilitate accurate gene expression analyses under the HMF in N. lugens. The verification approach illustrated in this study highlights the importance of identifying reliable RGs for future empirical studies of magnetobiology (including magnetoreception) that involve magnetic field intensity as a factor.
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Affiliation(s)
- Ying Zhang
- Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Plant Health & Crop Safety, Nanjing Agricultural University, Nanjing, China
| | - Luying Zeng
- Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Plant Health & Crop Safety, Nanjing Agricultural University, Nanjing, China
| | - Yongji Wei
- Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Plant Health & Crop Safety, Nanjing Agricultural University, Nanjing, China
| | - Ming Zhang
- Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Plant Health & Crop Safety, Nanjing Agricultural University, Nanjing, China
| | - Weidong Pan
- Beijing Key Laboratory of Bioelectromagnetics, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China
| | - Gregory A. Sword
- Department of Entomology, Texas A&M University, College Station, TX, United States
| | - Fei Yang
- Department of Entomology, Texas A&M University, College Station, TX, United States
| | - Fajun Chen
- Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Plant Health & Crop Safety, Nanjing Agricultural University, Nanjing, China
| | - Guijun Wan
- Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Plant Health & Crop Safety, Nanjing Agricultural University, Nanjing, China
- *Correspondence: Guijun Wan,
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6
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Alachkar A. Aromatic patterns: Tryptophan aromaticity as a catalyst for the emergence of life and rise of consciousness. Phys Life Rev 2022; 42:93-114. [PMID: 35905538 DOI: 10.1016/j.plrev.2022.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 07/12/2022] [Indexed: 11/28/2022]
Abstract
Sunlight held the key to the origin of life on Earth. The earliest life forms, cyanobacteria, captured the sunlight to generate energy through photosynthesis. Life on Earth evolved in accordance with the circadian rhythms tied to sensitivity to sunlight patterns. A unique feature of cyanobacterial photosynthetic proteins and circadian rhythms' molecules, and later of nearly all photon-sensing molecules throughout evolution, is that the aromatic amino acid tryptophan (Trp) resides at the center of light-harvesting active sites. In this perspective, I review the literature and integrate evidence from different scientific fields to explore the role Trp plays in photon-sensing capabilities of living organisms through its resonance delocalization of π-electrons. The observations presented here are the product of apparently unrelated phenomena throughout evolution, but nevertheless share consistent patterns of photon-sensing by Trp-containing and Trp-derived molecules. I posit the unique capacity to transfer electrons during photosynthesis in the earliest life forms is conferred to Trp due to its aromaticity. I propose this ability evolved to assume more complex functions, serving as a host for mechanisms underlying mental aptitudes - a concept which provides a theoretical basis for defining the neural correlates of consciousness. The argument made here is that Trp aromaticity may have allowed for the inception of the mechanistic building blocks used to fabricate complexity in higher forms of life. More specifically, Trp aromatic non-locality may have acted as a catalyst for the emergence of consciousness by instigating long-range synchronization and stabilizing the large-scale coherence of neural networks, which mediate functional brain activity. The concepts proposed in this perspective provide a conceptual foundation that invites further interdisciplinary dialogue aimed at examining and defining the role of aromaticity (beyond Trp) in the emergence of life and consciousness.
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Affiliation(s)
- Amal Alachkar
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, CA 92697, USA; UC Irvine Center for the Neurobiology of Learning and Memory, University of California-Irvine, Irvine, CA 92697, USA; Institute for Genomics and Bioinformatics, School of Information and Computer Sciences, University of California, Irvine, CA 92697, USA.
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7
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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; 208:97-106. [PMID: 35019998 PMCID: PMC8918455 DOI: 10.1007/s00359-021-01537-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [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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8
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Ozturk N. Light-dependent reactions of animal circadian photoreceptor cryptochrome. FEBS J 2021; 289:6622-6639. [PMID: 34750956 DOI: 10.1111/febs.16273] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/21/2021] [Accepted: 11/08/2021] [Indexed: 11/29/2022]
Abstract
Circadian rhythms are endogenous autonomous 24-h oscillations that are generated by a transcription-translation feedback loop (TTFL). In the positive arm of the TTFL, two transcription factors activate the expression of two genes of the negative arm as well as circadian clock-regulated genes. The circadian clocks are reset through photoreceptor proteins by sunlight in the early morning to keep synchrony with the geological clock. Among animal circadian photoreceptors, Drosophila Cryptochrome (DmCRY) has some unique properties because Drosophila has a single cryptochrome (CRY) that appears to have functions which are specific to organs or tissues, or even to a subset of cells. In mammals, CRYs are not photoreceptors but function in the TTFL, while insects have a light-insensitive mammalian-like CRY or a Drosophila-like photoreceptor CRY (or both). Here, we postulate that as being just one CRY in Drosophila, DmCRY might play different roles in different tissues/organs in a context-dependent manner. In addition to being a circadian photoreceptor/protein, attributing also a magnetoreception function to DmCRY has increased its workload. Considering that DmCRY senses photons as a photoreceptor but also can regulate many different events in a light-dependent manner, differential protein-protein interactions (PPIs) of DmCRY might play a critical role in the generation of such diverse outputs. Therefore, we need to add novel approaches in addition to the current ones to study multiple and context-dependent functions of DmCRY by adopting recently developed techniques. Successful identification of transient/fast PPIs on a scale of minutes would enhance our understanding of light-dependent and/or magnetoreception-associated reactions.
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Affiliation(s)
- Nuri Ozturk
- Molecular Biology and Genetics, Gebze Technical University, Turkey
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9
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Wong SY, Wei Y, Mouritsen H, Solov'yov IA, Hore PJ. Cryptochrome magnetoreception: four tryptophans could be better than three. J R Soc Interface 2021; 18:20210601. [PMID: 34753309 PMCID: PMC8580466 DOI: 10.1098/rsif.2021.0601] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 10/14/2021] [Indexed: 12/28/2022] Open
Abstract
The biophysical mechanism of the magnetic compass sensor in migratory songbirds is thought to involve photo-induced radical pairs formed in cryptochrome (Cry) flavoproteins located in photoreceptor cells in the eyes. In Cry4a-the most likely of the six known avian Crys to have a magnetic sensing function-four radical pair states are formed sequentially by the stepwise transfer of an electron along a chain of four tryptophan residues to the photo-excited flavin. In purified Cry4a from the migratory European robin, the third of these flavin-tryptophan radical pairs is more magnetically sensitive than the fourth, consistent with the smaller separation of the radicals in the former. Here, we explore the idea that these two radical pair states of Cry4a could exist in rapid dynamic equilibrium such that the key magnetic and kinetic properties are weighted averages. Spin dynamics simulations suggest that the third radical pair is largely responsible for magnetic sensing while the fourth may be better placed to initiate magnetic signalling particularly if the terminal tryptophan radical can be reduced by a nearby tyrosine. Such an arrangement could have allowed independent optimization of the essential sensing and signalling functions of the protein. It might also rationalize why avian Cry4a has four tryptophans while Crys from plants have only three.
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Affiliation(s)
- Siu Ying Wong
- Institut für Physik, Carl-von-Ossietzky Universität Oldenburg, Oldenburg 26111, Germany
| | - Yujing Wei
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, UK
| | - Henrik Mouritsen
- Institut für Biologie und Umweltwissenschaften, Carl-von-Ossietzky Universität Oldenburg, Oldenburg 26111, Germany
- Research Centre for Neurosensory Science, University of Oldenburg, Oldenburg 26111, Germany
| | - Ilia A. Solov'yov
- Institut für Physik, Carl-von-Ossietzky Universität Oldenburg, Oldenburg 26111, Germany
| | - P. J. Hore
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, UK
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10
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Einwich A, Seth PK, Bartölke R, Bolte P, Feederle R, Dedek K, Mouritsen H. Localisation of cryptochrome 2 in the avian retina. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2021; 208:69-81. [PMID: 34677638 PMCID: PMC8918457 DOI: 10.1007/s00359-021-01506-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 08/13/2021] [Accepted: 08/19/2021] [Indexed: 12/12/2022]
Abstract
Cryptochromes are photolyase-related blue-light receptors acting as core components of the mammalian circadian clock in the cell nuclei. One or more members of the cryptochrome protein family are also assumed to play a role in avian magnetoreception, but the primary sensory molecule in the retina of migratory birds that mediates light-dependent magnetic compass orientation has still not been identified. The mRNA of cryptochrome 2 (Cry2) has been reported to be located in the cell nuclei of the retina, but Cry2 localisation has not yet been demonstrated at the protein level. Here, we provide evidence that Cry2 protein is located in the photoreceptor inner segments, the outer nuclear layer, the inner nuclear layer and the ganglion cell layer in the retina of night-migratory European robins, homing pigeons and domestic chickens. At the subcellular level, we find Cry2 both in the cytoplasm and the nucleus of cells residing in these layers. This broad nucleic expression rather points to a role for avian Cry2 in the circadian clock and is consistent with a function as a transcription factor, analogous to mammalian Cry2, and speaks against an involvement in magnetoreception.
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Affiliation(s)
- Angelika Einwich
- Institute for Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Pranav Kumar Seth
- Institute for Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Rabea Bartölke
- Institute for Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Petra Bolte
- Institute for Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Regina Feederle
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute for Diabetes and Obesity, Monoclonal Antibody Core Facility, Neuherberg, Germany
| | - Karin Dedek
- Institute for Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany.,Research Centre for Neurosensory Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Henrik Mouritsen
- Institute for Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany. .,Research Centre for Neurosensory Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany.
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11
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Balay SD, Hochstoeger T, Vilceanu A, Malkemper EP, Snider W, Dürnberger G, Mechtler K, Schuechner S, Ogris E, Nordmann GC, Ushakova L, Nimpf S, Keays DA. The expression, localisation and interactome of pigeon CRY2. Sci Rep 2021; 11:20293. [PMID: 34645873 PMCID: PMC8514597 DOI: 10.1038/s41598-021-99207-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 09/13/2021] [Indexed: 11/18/2022] Open
Abstract
Cryptochromes (CRY) are highly conserved signalling molecules that regulate circadian rhythms and are candidate radical pair based magnetoreceptors. Birds have at least four cryptochromes (CRY1a, CRY1b, CRY2, and CRY4), but few studies have interrogated their function. Here we investigate the expression, localisation and interactome of clCRY2 in the pigeon retina. We report that clCRY2 has two distinct transcript variants, clCRY2a, and a previously unreported splice isoform, clCRY2b which is larger in size. We show that clCRY2a mRNA is expressed in all retinal layers and clCRY2b is enriched in the inner and outer nuclear layer. To define the localisation and interaction network of clCRY2 we generated and validated a monoclonal antibody that detects both clCRY2 isoforms. Immunohistochemical studies revealed that clCRY2a/b is present in all retinal layers and is enriched in the outer limiting membrane and outer plexiform layer. Proteomic analysis showed clCRY2a/b interacts with typical circadian molecules (PER2, CLOCK, ARTNL), cell junction proteins (CTNNA1, CTNNA2) and components associated with the microtubule motor dynein (DYNC1LI2, DCTN1, DCTN2, DCTN3) within the retina. Collectively these data show that clCRY2 is a component of the avian circadian clock and unexpectedly associates with the microtubule cytoskeleton.
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Affiliation(s)
- Spencer D Balay
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria.,Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, 1030, Vienna, Austria
| | - Tobias Hochstoeger
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria
| | - Alexandra Vilceanu
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria
| | - E Pascal Malkemper
- Max Planck Research Group Neurobiology of Magnetoreception, Center of Advanced European Studies and Research (Caesar), Ludwig-Erhard-Allee 2, 53175, Bonn, Germany
| | - William Snider
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, USA
| | - Gerhard Dürnberger
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria.,Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), Dr. Bohr-Gasse 3, 1030, Vienna, Austria
| | - Karl Mechtler
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria.,Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), Dr. Bohr-Gasse 3, 1030, Vienna, Austria
| | - Stefan Schuechner
- Monoclonal Antibody Facility, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9, 1030, Vienna, Austria
| | - Egon Ogris
- Monoclonal Antibody Facility, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9, 1030, Vienna, Austria
| | - Gregory C Nordmann
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria.,Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, 1030, Vienna, Austria
| | - Lyubov Ushakova
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria
| | - Simon Nimpf
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria
| | - David A Keays
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria. .,Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Australia. .,Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University Munich, Planegg-Martinsried, 82152, Munich, Germany.
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12
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Pinzon-Rodriguez A, Muheim R. Cryptochrome expression in avian UV cones: revisiting the role of CRY1 as magnetoreceptor. Sci Rep 2021; 11:12683. [PMID: 34135416 PMCID: PMC8209128 DOI: 10.1038/s41598-021-92056-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 06/03/2021] [Indexed: 02/05/2023] Open
Abstract
Cryptochromes (CRY) have been proposed as putative magnetoreceptors in vertebrates. Localisation of CRY1 in the UV cones in the retinas of birds suggested that it could be the candidate magnetoreceptor. However, recent findings argue against this possibility. CRY1 is a type II cryptochrome, a subtype of cryptochromes that may not be inherently photosensitive, and it exhibits a clear circadian expression in the retinas of birds. Here, we reassessed the localisation and distribution of CRY1 in the retina of the zebra finch. Zebra finches have a light-dependent magnetic compass based on a radical-pair mechanism, similar to migratory birds. We found that CRY1 colocalised with the UV/V opsin (SWS1) in the outer segments of UV cones, but restricted to the tip of the segments. CRY1 was found in all UV cones across the entire retina, with the highest densities near the fovea. Pre-exposure of birds to different wavelengths of light did not result in any difference in CRY1 detection, suggesting that CRY1 did not undergo any detectable functional changes as result of light activation. Considering that CRY1 is likely not involved in magnetoreception, our findings open the possibility for an involvement in different, yet undetermined functions in the avian UV/V cones.
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Affiliation(s)
- Atticus Pinzon-Rodriguez
- grid.4514.40000 0001 0930 2361Department of Biology, Lund University, Biology Building B, 223 62 Lund, Sweden
| | - Rachel Muheim
- grid.4514.40000 0001 0930 2361Department of Biology, Lund University, Biology Building B, 223 62 Lund, Sweden
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13
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Karki N, Vergish S, Zoltowski BD. Cryptochromes: Photochemical and structural insight into magnetoreception. Protein Sci 2021; 30:1521-1534. [PMID: 33993574 DOI: 10.1002/pro.4124] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/10/2021] [Accepted: 05/11/2021] [Indexed: 12/21/2022]
Abstract
Cryptochromes (CRYs) function as blue light photoreceptors in diverse physiological processes in nearly all kingdoms of life. Over the past several decades, they have emerged as the most likely candidates for light-dependent magnetoreception in animals, however, a long history of conflicts between in vitro photochemistry and in vivo behavioral data complicate validation of CRYs as a magnetosensor. In this review, we highlight the origins of conflicts regarding CRY photochemistry and signal transduction, and identify recent data that provides clarity on potential mechanisms of signal transduction in magnetoreception. The review primarily focuses on examining differences in photochemistry and signal transduction in plant and animal CRYs, and identifies potential modes of convergent evolution within these independent lineages that may identify conserved signaling pathways.
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Affiliation(s)
- Nischal Karki
- Department of Chemistry, Southern Methodist University, Dallas, Texas, USA
| | - Satyam Vergish
- Department of Chemistry, Southern Methodist University, Dallas, Texas, USA
| | - Brian D Zoltowski
- Department of Chemistry, Southern Methodist University, Dallas, Texas, USA
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14
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Kavet R, Brain J. Cryptochromes in Mammals and Birds: Clock or Magnetic Compass? Physiology (Bethesda) 2021; 36:183-194. [PMID: 33904789 DOI: 10.1152/physiol.00040.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Species throughout the animal kingdom use the Earth's magnetic field (MF) to navigate using either or both of two mechanisms. The first relies on magnetite crystals in tissue where their magnetic moments align with the MF to transduce a signal transmitted to the central nervous system. The second and the subject of this paper involves cryptochrome (CRY) proteins located in cone photoreceptors distributed across the retina, studied most extensively in birds. According to the "Radical Pair Mechanism" (RPM), blue/UV light excites CRY's flavin cofactor (FAD) to generate radical pairs whose singlet-to-triplet interconversion rate is modulated by an external MF. The signaling product of the RPM produces an impression of the field across the retinal surface. In birds, the resulting signal on the optic nerve is transmitted along the thalamofugal pathway to the primary visual cortex, which projects to brain regions concerned with image processing, memory, and executive function. The net result is a bird's orientation to the MF's inclination: its vector angle relative to the Earth's surface. The quality of ambient light (e.g., polarization) provides additional input to the compass. In birds, the Type IV CRY isoform appears pivotal to the compass, given its positioning within retinal cones; a cytosolic location therein indicating no role in the circadian clock; relatively steady diurnal levels (unlike Type II CRY's cycling); and a full complement of FAD (essential for photosensitivity). The evidence indicates that mammalian Type II CRY isoforms play a light-independent role in the cellular molecular clock without a photoreceptive function.
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Affiliation(s)
| | - Joseph Brain
- Environmental Physiology, Molecular, and Integrative Physiological Sciences Program, Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
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15
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Xue X, Ali YF, Luo W, Liu C, Zhou G, Liu NA. Biological Effects of Space Hypomagnetic Environment on Circadian Rhythm. Front Physiol 2021; 12:643943. [PMID: 33767637 PMCID: PMC7985258 DOI: 10.3389/fphys.2021.643943] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 02/12/2021] [Indexed: 11/13/2022] Open
Abstract
The intrinsic earth magnetic field (geomagnetic field, GMF) provides an essential environmental condition for most living organisms to adapt the solar cycle by rhythmically synchronizing physiological and behavioral processes. However, hypomagnetic field (HMF) of outer space, the Moon, and the Mars differs much from GMF, which poses a critical problem to astronauts during long-term interplanetary missions. Multiple experimental works have been devoted to the HMF effects on circadian rhythm and found that HMF perturbs circadian rhythms and profoundly contributes to health problems such as sleep disorders, altered metabolic as well as neurological diseases. By systemizing the latest progress on interdisciplinary cooperation between magnetobiology and chronobiology, this review sheds light on the health effects of HMF on circadian rhythms by elaborating the underlying circadian clock machinery and molecular processes.
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Affiliation(s)
- Xunwen Xue
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, China.,Academy of Space Life Sciences, Soochow University, Suzhou, China
| | - Yasser F Ali
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, China.,Academy of Space Life Sciences, Soochow University, Suzhou, China.,Biophysics lab, Physics Department, Faculty of Science, Al-Azhar University, Nasr City, Egypt
| | - Wanrong Luo
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, China.,Academy of Space Life Sciences, Soochow University, Suzhou, China
| | - Caorui Liu
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, China.,Academy of Space Life Sciences, Soochow University, Suzhou, China
| | - Guangming Zhou
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, China.,Academy of Space Life Sciences, Soochow University, Suzhou, China
| | - Ning-Ang Liu
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, China.,Academy of Space Life Sciences, Soochow University, Suzhou, China
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16
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Bolte P, Einwich A, Seth PK, Chetverikova R, Heyers D, Wojahn I, Janssen-Bienhold U, Feederle R, Hore P, Dedek K, Mouritsen H. Cryptochrome 1a localisation in light- and dark-adapted retinae of several migratory and non-migratory bird species: no signs of light-dependent activation. ETHOL ECOL EVOL 2021. [DOI: 10.1080/03949370.2020.1870571] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Petra Bolte
- Institute for Biology and Environmental Sciences, Carl-von-Ossietzky-University Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
| | - Angelika Einwich
- Institute for Biology and Environmental Sciences, Carl-von-Ossietzky-University Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
| | - Pranav K. Seth
- Institute for Biology and Environmental Sciences, Carl-von-Ossietzky-University Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
| | - Raisa Chetverikova
- Institute for Biology and Environmental Sciences, Carl-von-Ossietzky-University Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
| | - Dominik Heyers
- Institute for Biology and Environmental Sciences, Carl-von-Ossietzky-University Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
- Research Centre for Neurosensory Sciences, Carl-von-Ossietzky-University Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
| | - Irina Wojahn
- Institute for Biology and Environmental Sciences, Carl-von-Ossietzky-University Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
| | - Ulrike Janssen-Bienhold
- Research Centre for Neurosensory Sciences, Carl-von-Ossietzky-University Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
- Department of Neuroscience, Carl-von-Ossietzky-University Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
| | - Regina Feederle
- Institute for Diabetes and Obesity, Monoclonal Antibody Core Facility, Helmholtz Zentrum München, German Research Center for Environmental Health, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - Peter Hore
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Karin Dedek
- Institute for Biology and Environmental Sciences, Carl-von-Ossietzky-University Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
- Research Centre for Neurosensory Sciences, Carl-von-Ossietzky-University Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
| | - Henrik Mouritsen
- Institute for Biology and Environmental Sciences, Carl-von-Ossietzky-University Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
- Research Centre for Neurosensory Sciences, Carl-von-Ossietzky-University Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
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17
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Einwich A, Dedek K, Seth PK, Laubinger S, Mouritsen H. A novel isoform of cryptochrome 4 (Cry4b) is expressed in the retina of a night-migratory songbird. Sci Rep 2020; 10:15794. [PMID: 32978454 PMCID: PMC7519125 DOI: 10.1038/s41598-020-72579-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 07/28/2020] [Indexed: 01/22/2023] Open
Abstract
The primary sensory molecule underlying light-dependent magnetic compass orientation in migratory birds has still not been identified. The cryptochromes are the only known class of vertebrate proteins which could mediate this mechanism in the avian retina. Cryptochrome 4 of the night-migratory songbird the European robin (Erithacus rubecula; erCry4) has several of the properties needed to be the primary magnetoreceptor in the avian eye. Here, we report on the identification of a novel isoform of erCry4, which we named erCry4b. Cry4b includes an additional exon of 29 amino acids compared to the previously described form of Cry4, now called Cry4a. When comparing the retinal circadian mRNA expression pattern of the already known isoform erCry4a and the novel erCry4b isoform, we find that erCry4a is stably expressed throughout day and night, whereas erCry4b shows a diurnal mRNA oscillation. The differential characteristics of the two erCry4 isoforms regarding their 24-h rhythmicity in mRNA expression leads us to suggest that they might have different functions. Based on the 24-h expression pattern, erCry4a remains the more likely cryptochrome to be involved in radical-pair-based magnetoreception, but at the present time, an involvement of erCry4b cannot be excluded.
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Affiliation(s)
- Angelika Einwich
- Institute for Biology and Environmental Sciences, Neurosensorics/Animal Navigation, Carl-von-Ossietzky-Universität Oldenburg, Oldenburg, Germany.,Research Centre for Neurosensory Sciences, Carl-von-Ossietzky-Universität Oldenburg, Oldenburg, Germany
| | - Karin Dedek
- Institute for Biology and Environmental Sciences, Neurosensorics/Animal Navigation, Carl-von-Ossietzky-Universität Oldenburg, Oldenburg, Germany.,Research Centre for Neurosensory Sciences, Carl-von-Ossietzky-Universität Oldenburg, Oldenburg, Germany
| | - Pranav Kumar Seth
- Institute for Biology and Environmental Sciences, Neurosensorics/Animal Navigation, Carl-von-Ossietzky-Universität Oldenburg, Oldenburg, Germany.,Research Centre for Neurosensory Sciences, Carl-von-Ossietzky-Universität Oldenburg, Oldenburg, Germany
| | - Sascha Laubinger
- Institute for Biology and Environmental Sciences, Evolutionäre Genetik der Pflanzen, Carl-von-Ossietzky-Universität Oldenburg, Oldenburg, Germany
| | - Henrik Mouritsen
- Institute for Biology and Environmental Sciences, Neurosensorics/Animal Navigation, Carl-von-Ossietzky-Universität Oldenburg, Oldenburg, Germany. .,Research Centre for Neurosensory Sciences, Carl-von-Ossietzky-Universität Oldenburg, Oldenburg, Germany.
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18
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Otsuka H, Mitsui H, Miura K, Okano K, Imamoto Y, Okano T. Rapid Oxidation Following Photoreduction in the Avian Cryptochrome4 Photocycle. Biochemistry 2020; 59:3615-3625. [PMID: 32915550 DOI: 10.1021/acs.biochem.0c00495] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Avian magnetoreception is assumed to occur in the retina. Although its molecular mechanism is unclear, magnetic field-dependent formation and the stability of radical-containing photointermediate(s) are suggested to play key roles in a hypothesis called the radical pair mechanism. Chicken cryptochrome4 (cCRY4) has been identified as a candidate magnetoreceptive molecule due to its expression in the retina and its ability to form stable flavin neutral radicals (FADH●) upon blue light absorption. Herein, we used millisecond flash photolysis to investigate the cCRY4 photocycle, in both the presence and absence of dithiothreitol (DTT); detecting the anion radical form of FAD (FAD●-) under both conditions. Using spectral data obtained during flash photolysis and UV-visible photospectroscopy, we estimated the absolute absorbance spectra of the photointermediates, thus allowing us to decompose each spectrum into its individual components. Notably, in the absence of DTT, approximately 37% and 63% of FAD●- was oxidized to FADOX and protonated to form FADH●, respectively. Singular value decomposition analysis suggested the presence of two FAD●- molecular species, each of which was destined to be oxidized to FADOX or protonated to FADH●. A tyrosine neutral radical was also detected; however, it likely decayed concomitantly with the oxidation of FAD●-. On the basis of these results, we considered the occurrence of bifurcation prior to FAD●- generation, or during FAD●- oxidization, and discussed the potential role played by the tyrosine radical in the radical pair mechanism.
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Affiliation(s)
- Hiroaki Otsuka
- Department of Electrical Engineering and Bioscience, Graduate School of Sciences and Engineering, Waseda University, TWIns, Wakamatsucho 2-2, Shinjuku-Ku, Tokyo 162-8480, Japan
| | - Hiromasa Mitsui
- Department of Electrical Engineering and Bioscience, Graduate School of Sciences and Engineering, Waseda University, TWIns, Wakamatsucho 2-2, Shinjuku-Ku, Tokyo 162-8480, Japan
| | - Kota Miura
- Department of Electrical Engineering and Bioscience, Graduate School of Sciences and Engineering, Waseda University, TWIns, Wakamatsucho 2-2, Shinjuku-Ku, Tokyo 162-8480, Japan
| | - Keiko Okano
- Department of Electrical Engineering and Bioscience, Graduate School of Sciences and Engineering, Waseda University, TWIns, Wakamatsucho 2-2, Shinjuku-Ku, Tokyo 162-8480, Japan
| | - Yasushi Imamoto
- Department of Biophysics, Division of Biological Sciences, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-Ku, Kyoto 606-8502, Japan
| | - Toshiyuki Okano
- Department of Electrical Engineering and Bioscience, Graduate School of Sciences and Engineering, Waseda University, TWIns, Wakamatsucho 2-2, Shinjuku-Ku, Tokyo 162-8480, Japan
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19
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Hochstoeger T, Al Said T, Maestre D, Walter F, Vilceanu A, Pedron M, Cushion TD, Snider W, Nimpf S, Nordmann GC, Landler L, Edelman N, Kruppa L, Dürnberger G, Mechtler K, Schuechner S, Ogris E, Malkemper EP, Weber S, Schleicher E, Keays DA. The biophysical, molecular, and anatomical landscape of pigeon CRY4: A candidate light-based quantal magnetosensor. SCIENCE ADVANCES 2020; 6:eabb9110. [PMID: 32851187 PMCID: PMC7423367 DOI: 10.1126/sciadv.abb9110] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 06/26/2020] [Indexed: 06/11/2023]
Abstract
The biophysical and molecular mechanisms that enable animals to detect magnetic fields are unknown. It has been proposed that birds have a light-dependent magnetic compass that relies on the formation of radical pairs within cryptochrome molecules. Using spectroscopic methods, we show that pigeon cryptochrome clCRY4 is photoreduced efficiently and forms long-lived spin-correlated radical pairs via a tetrad of tryptophan residues. We report that clCRY4 is broadly and stably expressed within the retina but enriched at synapses in the outer plexiform layer in a repetitive manner. A proteomic survey for retinal-specific clCRY4 interactors identified molecules that are involved in receptor signaling, including glutamate receptor-interacting protein 2, which colocalizes with clCRY4. Our data support a model whereby clCRY4 acts as an ultraviolet-blue photoreceptor and/or a light-dependent magnetosensor by modulating glutamatergic synapses between horizontal cells and cones.
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Affiliation(s)
- Tobias Hochstoeger
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, Vienna 1030, Austria
| | - Tarek Al Said
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, Freiburg 79104, Germany
| | - Dante Maestre
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, Vienna 1030, Austria
| | - Florian Walter
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, Vienna 1030, Austria
| | - Alexandra Vilceanu
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, Vienna 1030, Austria
| | - Miriam Pedron
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, Vienna 1030, Austria
| | - Thomas D. Cushion
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, Vienna 1030, Austria
| | - William Snider
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Simon Nimpf
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, Vienna 1030, Austria
| | - Gregory Charles Nordmann
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, Vienna 1030, Austria
| | - Lukas Landler
- Institute of Zoology, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria
| | - Nathaniel Edelman
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Lennard Kruppa
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, Freiburg 79104, Germany
| | - Gerhard Dürnberger
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, Vienna 1030, Austria
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), VBC, Dr. Bohr-Gasse 3, Vienna 1030, Austria
| | - Karl Mechtler
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, Vienna 1030, Austria
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), VBC, Dr. Bohr-Gasse 3, Vienna 1030, Austria
| | - Stefan Schuechner
- Monoclonal Antibody Facility, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9, Vienna 1030, Austria
| | - Egon Ogris
- Monoclonal Antibody Facility, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9, Vienna 1030, Austria
| | - E. Pascal Malkemper
- Monoclonal Antibody Facility, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9, Vienna 1030, Austria
- Max Planck Research Group Neurobiology of Magnetoreception, Center of Advanced European Studies and Research (CAESAR), Ludwig-Erhard-Allee 2, Bonn 53175, Germany
| | - Stefan Weber
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, Freiburg 79104, Germany
| | - Erik Schleicher
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, Freiburg 79104, Germany
| | - David A. Keays
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus-Vienna-Biocenter 1, Vienna 1030, Austria
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Australia
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University Munich, Planegg-Martinsried 82152, Germany
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20
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Vanderstraeten J, Gailly P, Malkemper EP. Light entrainment of retinal biorhythms: cryptochrome 2 as candidate photoreceptor in mammals. Cell Mol Life Sci 2020; 77:875-884. [PMID: 31982933 PMCID: PMC11104904 DOI: 10.1007/s00018-020-03463-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 01/08/2020] [Accepted: 01/14/2020] [Indexed: 12/31/2022]
Abstract
The mechanisms that synchronize the biorhythms of the mammalian retina with the light/dark cycle are independent of those synchronizing the rhythms in the central pacemaker, the suprachiasmatic nucleus. The identity of the photoreceptor(s) responsible for the light entrainment of the retina of mammals is still a matter of debate, and recent studies have reported contradictory results in this respect. Here, we suggest that cryptochromes (CRY), in particular CRY 2, are involved in that light entrainment. CRY are highly conserved proteins that are a key component of the cellular circadian clock machinery. In plants and insects, they are responsible for the light entrainment of these biorhythms, mediated by the light response of their flavin cofactor (FAD). In mammals, however, no light-dependent role is currently assumed for CRY in light-exposed tissues, including the retina. It has been reported that FAD influences the function of mammalian CRY 2 and that human CRY 2 responds to light in Drosophila, suggesting that mammalian CRY 2 keeps the ability to respond to light. Here, we hypothesize that CRY 2 plays a role in the light entrainment of retinal biorhythms, at least in diurnal mammals. Indeed, published data shows that the light intensity dependence and the wavelength sensitivity commonly reported for that light entrainment fits the light sensitivity and absorption spectrum of light-responsive CRY. We propose experiments to test our hypothesis and to further explore the still-pending question of the function of CRY 2 in the mammalian retina.
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Affiliation(s)
- Jacques Vanderstraeten
- Faculty of Medicine, School of Public Health, Environmental and Work Health Research Center, Université Libre de Bruxelles, CP593, Route de Lennik, 808, 1070, Brussels, Belgium.
- , Avenue Constant Montald, 11, 1200, Brussels, Belgium.
| | - Philippe Gailly
- Faculty of Medicine, Institute of Neuroscience (IONS), Cellular and Molecular Pole (CEMO), Catholic University of Louvain, Avenue Mounier 53/B1.53.17, 1200, Brussels, Belgium
| | - E Pascal Malkemper
- Center of Advanced European Studies and Research (CAESAR), Ludwig-Erhard-Allee 2, Bonn, 53175, Germany
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21
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Margiotta JF, Howard MJ. Cryptochromes Mediate Intrinsic Photomechanical Transduction in Avian Iris and Somatic Striated Muscle. Front Physiol 2020; 11:128. [PMID: 32153427 PMCID: PMC7047837 DOI: 10.3389/fphys.2020.00128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 02/06/2020] [Indexed: 01/12/2023] Open
Abstract
Irises isolated from the eyes of diverse species constrict when exposed to light. Depending on species this intrinsic photomechanical transduction response (PMTR) requires either melanopsin or cryptochrome (CRY) photopigment proteins, generated by their respective association with retinoid or flavin adenine dinucleotide (FAD) chromophores. Although developmentally relevant circadian rhythms are also synchronized and reset by these same proteins, the cell type, mechanism, and specificity of photomechanical transduction (PMT) and its relationship to circadian processes remain poorly understood. Here we show that PMTRs consistent with CRY activation by 430 nm blue light occur in developing chicken iris striated muscle, identify relevant mechanisms, and demonstrate that similar PMTRs occur in striated iris and pectoral muscle fibers, prevented in both cases by knocking down CRY gene transcript levels. Supporting CRY activation, iris PMTRs were reduced by inhibiting flavin reductase, but unaffected by melanopsin antagonism. The largest iris PMTRs paralleled the developmental predominance of striated over smooth muscle fibers, and shared their requirement for extracellular Ca2+ influx and release of intracellular Ca2+. Photo-stimulation of identified striated myotubes maintained in dissociated culture revealed the cellular and molecular bases of PMT. Myotubes in iris cell cultures responded to 435 nm light with increased intracellular Ca2+ and contractions, mimicking iris PMTRs and their spectral sensitivity. Interestingly PMTRs featuring contractions and requiring extracellular Ca2+ influx and release of intracellular Ca2+ were also displayed by striated myotubes derived from pectoral muscle. Consistent with these findings, cytosolic CRY1 and CRY2 proteins were detected in both iris and pectoral myotubes, and knocking down myotube CRY1/CRY2 gene transcript levels specifically blocked PMTRs in both cases. Thus CRY-mediated PMT is not unique to iris, but instead reflects a more general feature of developing striated muscle fibers. Because CRYs are core timing components of circadian clocks and CRY2 is critical for circadian regulation of myogenic differentiation CRY-mediated PMT may interact with cell autonomous clocks to influence the progression of striated muscle development.
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Affiliation(s)
- Joseph F Margiotta
- Department of Neurosciences, University of Toledo College of Medicine and Life Sciences, Toledo, OH, United States
| | - Marthe J Howard
- Department of Neurosciences, University of Toledo College of Medicine and Life Sciences, Toledo, OH, United States
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22
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Zoltowski BD, Chelliah Y, Wickramaratne A, Jarocha L, Karki N, Xu W, Mouritsen H, Hore PJ, Hibbs RE, Green CB, Takahashi JS. Chemical and structural analysis of a photoactive vertebrate cryptochrome from pigeon. Proc Natl Acad Sci U S A 2019; 116:19449-19457. [PMID: 31484780 PMCID: PMC6765304 DOI: 10.1073/pnas.1907875116] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Computational and biochemical studies implicate the blue-light sensor cryptochrome (CRY) as an endogenous light-dependent magnetosensor enabling migratory birds to navigate using the Earth's magnetic field. Validation of such a mechanism has been hampered by the absence of structures of vertebrate CRYs that have functional photochemistry. Here we present crystal structures of Columba livia (pigeon) CRY4 that reveal evolutionarily conserved modifications to a sequence of Trp residues (Trp-triad) required for CRY photoreduction. In ClCRY4, the Trp-triad chain is extended to include a fourth Trp (W369) and a Tyr (Y319) residue at the protein surface that imparts an unusually high quantum yield of photoreduction. These results are consistent with observations of night migratory behavior in animals at low light levels and could have implications for photochemical pathways allowing magnetosensing.
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Affiliation(s)
- Brian D Zoltowski
- Department of Chemistry, Southern Methodist University, Dallas, TX 75275
- Center for Drug Discovery, Design, and Delivery, Southern Methodist University, Dallas, TX 75275
| | - Yogarany Chelliah
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Anushka Wickramaratne
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Lauren Jarocha
- Department of Chemistry, University of Oxford, OX1 3QZ Oxford, United Kingdom
| | - Nischal Karki
- Department of Chemistry, Southern Methodist University, Dallas, TX 75275
- Center for Drug Discovery, Design, and Delivery, Southern Methodist University, Dallas, TX 75275
| | - Wei Xu
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Henrik Mouritsen
- Institute for Biology and Environmental Sciences, Carl von Ossietzky University of Oldenburg, DE-26111 Oldenburg, Germany
- Research Center for Neurosensory Sciences, University of Oldenburg, DE-26111 Oldenburg, Germany
| | - Peter J Hore
- Department of Chemistry, University of Oxford, OX1 3QZ Oxford, United Kingdom
| | - Ryan E Hibbs
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Carla B Green
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Joseph S Takahashi
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390;
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
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Hore PJ. Upper bound on the biological effects of 50/60 Hz magnetic fields mediated by radical pairs. eLife 2019; 8:44179. [PMID: 30801245 PMCID: PMC6417859 DOI: 10.7554/elife.44179] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 02/02/2019] [Indexed: 01/02/2023] Open
Abstract
Prolonged exposure to weak (~1 μT) extremely-low-frequency (ELF, 50/60 Hz) magnetic fields has been associated with an increased risk of childhood leukaemia. One of the few biophysical mechanisms that might account for this link involves short-lived chemical reaction intermediates known as radical pairs. In this report, we use spin dynamics simulations to derive an upper bound of 10 parts per million on the effect of a 1 μT ELF magnetic field on the yield of a radical pair reaction. By comparing this figure with the corresponding effects of changes in the strength of the Earth’s magnetic field, we conclude that if exposure to such weak 50/60 Hz magnetic fields has any effect on human biology, and results from a radical pair mechanism, then the risk should be no greater than travelling a few kilometres towards or away from the geomagnetic north or south pole.
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Affiliation(s)
- P J Hore
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, Oxford, United Kingdom
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