Localisation of cryptochrome 2 in the avian retina

Einwich, Angelika; Seth, Pranav Kumar; Bartölke, Rabea; Bolte, Petra; Feederle, Regina; Dedek, Karin; Mouritsen, Henrik

doi:10.1007/s00359-021-01506-1

Cited by 16 publications

(13 citation statements)

References 81 publications

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“…Cryptochromes (Cry), currently the only group of vertebrate proteins known to form radical pairs upon photoexcitation (Ritz et al 2000 ; Liedvogel et al 2007 ; Maeda et al 2012 ; Zoltowski et al 2019 ; Xu et al 2021 ), have been proposed as the light-activated, radical-pair-forming, magnetosensory proteins in the avian retina (Ritz et al 2000 ; Mouritsen et al 2004 ; Maeda et al 2012 ; Nießner et al 2014 ; but see Bolte et al 2021 ; Hore and Mouritsen 2016 ; Günther et al 2018 ; Xu et al 2021 ; Wong et al 2021 ). At least six different cryptochrome variants are known to occur in retinal neurons of night-migratory songbirds: Cry1a (Mouritsen et al 2004 ; Möller et al 2004 ; Nießner et al 2011 ; Bolte et al 2021 ), Cry1b (Möller et al 2004 ; Bolte et al 2016 ; Nießner et al 2016 ), Cry2a (Mouritsen et al 2004 ; Möller et al 2004 ; Balay et al 2021 ; Einwich et al 2021 ), Cry2b (Hochstoeger et al 2020 ; Balay et al 2021 ), Cry4a (Liedvogel and Mouritsen 2010 ; Günther et al 2018 ; Wu et al 2020 ; Xu et al 2021 ), and Cry4b (Einwich et al 2020 ); a and b forms are alternative splicing variants.…”

Section: Introductionmentioning

confidence: 99%

Broadband 75–85 MHz radiofrequency fields disrupt magnetic compass orientation in night-migratory songbirds consistent with a flavin-based radical pair magnetoreceptor

et al. 2022

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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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Section: Introductionmentioning

confidence: 99%

Broadband 75–85 MHz radiofrequency fields disrupt magnetic compass orientation in night-migratory songbirds consistent with a flavin-based radical pair magnetoreceptor

et al. 2022

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“…The magnetic compass sense of night-migratory birds seems to be based on a light-dependent, radical-pair-based mechanism in cryptochrome proteins [1,2,[26][27][28][29][30][31][32][33][34][35][36][37] located in both of the birds' eyes [38][39][40][41]. Among the six cryptochromes known from bird retinas [15,36,[42][43][44][45][46][47][48][49][50][51], cryptochrome 4 (Cry4) seems particularly interesting because it binds the cofactor flavin, which is crucial for any magnetic sensitivity of any cryptochrome [36,46,[52][53][54]. So far, there is no convincing evidence of flavin binding in other types of vertebrate cryptochomes, e.g.…”

Section: Introductionmentioning

confidence: 99%

Double cones in the avian retina form an oriented mosaic which might facilitate magnetoreception and/or polarized light sensing

Chetverikova

Dautaj

Schwigon

et al. 2022

J. R. Soc. Interface.

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To navigate between breeding and wintering grounds, night-migratory songbirds are aided by a light-dependent magnetic compass sense and maybe also by polarized light vision. Although the underlying mechanisms for magnetoreception and polarized light sensing remain unclear, double cone photoreceptors in the avian retina have been suggested to represent the primary sensory cells. To use these senses, birds must be able to separate the directional information from the Earth's magnetic field and/or light polarization from variations in light intensity. Theoretical considerations suggest that this could be best achieved if neighbouring double cones were oriented in an ordered pattern. Therefore, we investigate the orientation patterns of double cones in European robins ( Erithacus rubecula ) and domestic chickens ( Gallus gallus domesticus ). We used whole-mounted retinas labelled with double cone markers to quantify the orientations of individual double cones in relation to their nearest neighbours. In both species, our data show that the double cone array is highly ordered: the angles between neighbouring double cones were more likely to be 90°/−90° in the central retina and 180°/0° in the peripheral retina, respectively. The observed regularity in double cone orientation could aid the cells' putative function in light-dependent magnetoreception and/or polarized light sensing.

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“…Based on these findings, Mouritsen et al ( 2005 ) proposed that this night-vision processing could be related to a vision-mediated magnetic compass based on radical-pair-forming sensor molecules, cryptochromes, located in the birds eyes (Ritz et al 2000 ; Hore and Mouritsen 2016 ; Mouritsen 2018 , 2021 ). Cryptochromes are currently considered the most likely molecular basis for a radical pair-based magnetic compass sense in birds (Möller et al 2004 ; Mouritsen et al 2004b ; Liedvogel et al 2007b ; Niessner et al 2011 , 2016 ; Bolte et al 2016 , 2021 ; Hore and Mouritsen 2016 ; Günther et al 2018 ; Zoltowski et al 2019 ; Einwich et al 2020 , 2021 ; Xu et al 2021 ). Connectivity studies have shown that the eye and Cluster N are interconnected via parts of the thalamofugal visual pathway (Heyers et al 2007 ).…”

Section: Introductionmentioning

confidence: 99%

Morphology, biochemistry and connectivity of Cluster N and the hippocampal formation in a migratory bird

et al. 2022

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The exceptional navigational capabilities of migrating birds are based on the perception and integration of a variety of natural orientation cues. The "Wulst" in the forebrain of night-migratory songbirds contains a brain area named "Cluster N", which is involved in processing directional navigational information derived from the Earth´s magnetic field. Cluster N is medially joined by the hippocampal formation, known to retrieve and utilise navigational information. To investigate the connectivity and neurochemical characteristics of Cluster N and the hippocampal formation of migratory birds, we performed morphological and histochemical analyses based on the expression of calbindin, calretinin, parvalbumin, glutamate receptor type 1 and early growth response protein-1 in the night-migratory Garden warbler (Sylvia borin) and mapped their mutual connections using neuronal tract tracing. The resulting expression patterns revealed regionally restricted neurochemical features, which mapped well onto the hippocampal and hyperpallial substructures known from other avian species. Magnetic fieldinduced neuronal activation covered caudal parts of the hyperpallium and the medially adjacent hippocampal dorsomedial/ dorsolateral subdivisions. Neuronal tract tracings revealed connections between Cluster N and the hippocampal formation with the vast majority originating from the densocellular hyperpallium, either directly or indirectly via the area corticoidea dorsolateralis. Our data indicate that the densocellular hyperpallium could represent a central relay for the transmission of magnetic compass information to the hippocampal formation where it might be integrated with other navigational cues in night-migratory songbirds.

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Localisation of cryptochrome 2 in the avian retina

Cited by 16 publications

References 81 publications

Broadband 75–85 MHz radiofrequency fields disrupt magnetic compass orientation in night-migratory songbirds consistent with a flavin-based radical pair magnetoreceptor

Broadband 75–85 MHz radiofrequency fields disrupt magnetic compass orientation in night-migratory songbirds consistent with a flavin-based radical pair magnetoreceptor

Double cones in the avian retina form an oriented mosaic which might facilitate magnetoreception and/or polarized light sensing

Morphology, biochemistry and connectivity of Cluster N and the hippocampal formation in a migratory bird

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