scholarly journals Cryptochrome expression in avian UV cones: revisiting the role of CRY1 as magnetoreceptor

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Atticus Pinzon-Rodriguez ◽  
Rachel Muheim
Keyword(s):  
Zebra Finch ◽  
Migratory Birds ◽  
Radical Pair ◽  
Magnetic Compass ◽  
Radical Pair Mechanism ◽  
Type Ii ◽  
Light Activation ◽  
Functional Changes ◽  
Circadian Expression

AbstractCryptochromes (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.

scholarly journals Cryptochrome Expression in Avian UV Cones: Revisiting the Role of Cry1 As Magnetoreceptor

2020 ◽  
Author(s):  
Atticus Pinzon-Rodriguez ◽  
Rachel Muheim
Keyword(s):  
Zebra Finch ◽  
Migratory Birds ◽  
Radical Pair ◽  
Magnetic Compass ◽  
Radical Pair Mechanism ◽  
Type Ii ◽  
Light Activation ◽  
Functional Changes ◽  
Circadian Expression

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 localization 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 colocalized with the UV/V opsin (SWS1) in the outer segments of UV cones, but restricted to the tip of the segments. Cry1 was expressed 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 expression, 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.

scholarly journals The magnetic compass mechanisms of birds and rodents are based on different physical principles

2006 ◽  
Vol 3 (9) ◽  
pp. 583-587 ◽  
Author(s):  
Peter Thalau ◽  
Thorsten Ritz ◽  
Hynek Burda ◽  
Regina E Wegner ◽  
Roswitha Wiltschko
Keyword(s):  
Geomagnetic Field ◽  
Migratory Birds ◽  
Radical Pair ◽  
Broad Band ◽  
Static Field ◽  
Magnetic Compass ◽  
Radical Pair Mechanism ◽  
Zeeman Frequency ◽  
Compass Mechanisms ◽  
Physical Principles

Recently, oscillating magnetic fields in the MHz-range were introduced as a useful diagnostic tool to identify the mechanism underlying magnetoreception. The effect of very weak high-frequency fields on the orientation of migratory birds indicates that the avian magnetic compass is based on a radical pair mechanism. To analyse the nature of the magnetic compass of mammals, we tested rodents, Ansell's mole-rats, using their tendency to build their nests in the southern part of the arena as a criterion whether or not they could orient. In contrast to birds, their orientation was not disrupted when a broad-band field of 0.1–10 MHz of 85 nT or a 1.315 MHz field of 480 nT was added to the static geomagnetic field of 46 000 nT. Even increasing the intensity of the 1.315 MHz field (Zeeman frequency in the local geomagnetic field) to 4800 nT, more than a tenth of the static field, the mole-rats remained unaffected and continued to build their nests in the south. These results indicate that in contrast to that of birds, their magnetic compass does not involve radical pair processes; it seems to be based on a fundamentally different principle, which probably involves magnetite.

Resonance effects indicate a radical-pair mechanism for avian magnetic compass

Nature ◽  
2004 ◽  
Vol 429 (6988) ◽  
pp. 177-180 ◽  
Author(s):  
Thorsten Ritz ◽  
Peter Thalau ◽  
John B. Phillips ◽  
Roswitha Wiltschko ◽  
Wolfgang Wiltschko
Keyword(s):  
Radical Pair ◽  
Magnetic Compass ◽  
Radical Pair Mechanism ◽  
Resonance Effects

scholarly journals Stable inhibition of interleukin 1 receptor type II in Ishikawa cells augments secretion of matrix metalloproteinases: possible role in endometriosis pathophysiology

Reproduction ◽  
2007 ◽  
Vol 134 (3) ◽  
pp. 525-534 ◽  
Author(s):  
S Guay ◽  
A Akoum
Keyword(s):  
Interleukin 1 ◽  
Receptor Type ◽  
Type Ii ◽  
Endometrial Cells ◽  
Functional Changes ◽  
Empty Vector ◽  
Ishikawa Cells ◽  
Empty Expression Vector

Our previous studies showed a marked deficiency in interleukin 1 receptor type II (IL1R2) in the endometrial tissue of women with endometriosis, particularly in epithelial cells. We believe that such a deficiency in IL1R2, a potent and specific IL1 inhibitor, makes endometrial cells more sensitive to IL1 and less capable of buffering the cytokine’s effects, which may lead to functional changes that favor endometriosis development. The main objective of our study was to stably inhibit IL1R2 expression in endometrial cells in order to evaluate the role of IL1R2 deficiency in endometriosis pathophysiology. Stable clones of Ishikawa adenocarcinoma endometrial cells transfected with IL1R2 antisense and showing downregulation of IL1R2 protein expression, or with the empty expression vector alone and showing no noticeable difference in IL1R2 expression, were selected. The downregulation of IL1R2 expression in IL1R2 antisense transfectants when compared with control cells was confirmed by ELISA, Western blot and immunofluorescence. In these cells, IL1R2 expression was markedly reduced, compared with non-transfected cells or cells transfected with the empty vector, and there was a significant increase in the basal and the IL1-β (IL1B)-induced levels of matrix metalloproteinase (MMP)-2 and MMP-9 secretion. Furthermore, a significant decrease in IL1B-induced secretion of tissue inhibitor of MMPs-1, a known MMP-9 inhibitor, was observed. These in vitro data make plausible a role for IL1R2 deficiency in the capability of endometrial cells to invade the host tissue and develop in ectopic locations.

scholarly journals Electromagnetic 0.1–100 kHz noise does not disrupt orientation in a night-migrating songbird implying a spin coherence lifetime of less than 10 µs

2019 ◽  
Vol 16 (161) ◽  
pp. 20190716 ◽  
Author(s):  
Dmitry Kobylkov ◽  
Joe Wynn ◽  
Michael Winklhofer ◽  
Raisa Chetverikova ◽  
Jingjing Xu ◽  
...  
Keyword(s):  
Electromagnetic Fields ◽  
Migratory Birds ◽  
Radical Pair ◽  
Coherence Time ◽  
Magnetic Compass ◽  
Radio Waves ◽  
Spin Coherence ◽  
Compass Orientation ◽  
Magnetic Compass Orientation ◽  
Migrating Birds

According to the currently prevailing theory, the magnetic compass sense in night-migrating birds relies on a light-dependent radical-pair-based mechanism. It has been shown that radio waves at megahertz frequencies disrupt magnetic orientation in migratory birds, providing evidence for a quantum-mechanical origin of the magnetic compass. Still, many crucial properties, e.g. the lifetime of the proposed magnetically sensitive radical pair, remain unknown. The current study aims to estimate the spin coherence time of the radical pair, based on the behavioural responses of migratory birds to broadband electromagnetic fields covering the frequency band 0.1–100 kHz. A finding that the birds were unable to use their magnetic compass under these conditions would imply surprisingly long-lived (greater than 10 µs) spin coherence. However, we observed no effect of 0.1–100 kHz radiofrequency (RF) fields on the orientation of night-migratory Eurasian blackcaps ( Sylvia atricapilla ). This suggests that the lifetime of the spin coherence involved in magnetoreception is shorter than the period of the highest frequency RF fields used in this experiment (i.e. approx. 10 µs). This result, in combination with an earlier study showing that 20–450 kHz electromagnetic fields disrupt magnetic compass orientation, suggests that the spin coherence lifetime of the magnetically sensitive radical pair is in the range 2–10 µs.

scholarly journals The quantum needle of the avian magnetic compass

2016 ◽  
Vol 113 (17) ◽  
pp. 4634-4639 ◽  
Author(s):  
Hamish G. Hiscock ◽  
Susannah Worster ◽  
Daniel R. Kattnig ◽  
Charlotte Steers ◽  
Ye Jin ◽  
...  
Keyword(s):  
Migratory Birds ◽  
Radical Pair ◽  
Spin Dynamics ◽  
Energy Levels ◽  
Magnetic Compass ◽  
Spin Coherence ◽  
Radical Pairs ◽  
Sharp Feature ◽  
In The Wild ◽  
Dynamics Simulations

Migratory birds have a light-dependent magnetic compass, the mechanism of which is thought to involve radical pairs formed photochemically in cryptochrome proteins in the retina. Theoretical descriptions of this compass have thus far been unable to account for the high precision with which birds are able to detect the direction of the Earth's magnetic field. Here we use coherent spin dynamics simulations to explore the behavior of realistic models of cryptochrome-based radical pairs. We show that when the spin coherence persists for longer than a few microseconds, the output of the sensor contains a sharp feature, referred to as a spike. The spike arises from avoided crossings of the quantum mechanical spin energy-levels of radicals formed in cryptochromes. Such a feature could deliver a heading precision sufficient to explain the navigational behavior of migratory birds in the wild. Our results (i) afford new insights into radical pair magnetoreception, (ii) suggest ways in which the performance of the compass could have been optimized by evolution, (iii) may provide the beginnings of an explanation for the magnetic disorientation of migratory birds exposed to anthropogenic electromagnetic noise, and (iv) suggest that radical pair magnetoreception may be more of a quantum biology phenomenon than previously realized.

scholarly journals Polarized light modulates light-dependent magnetic compass orientation in birds

2016 ◽  
Vol 113 (6) ◽  
pp. 1654-1659 ◽  
Author(s):  
Rachel Muheim ◽  
Sissel Sjöberg ◽  
Atticus Pinzon-Rodriguez
Keyword(s):  
Magnetic Field ◽  
Radical Pair ◽  
Polarized Light ◽  
Magnetic Compass ◽  
Radical Pair Mechanism ◽  
Magnetic Field Effects ◽  
Compass Orientation ◽  
Magnetic Compass Orientation ◽  
Avian Retina ◽  
The Magnetic Field

Magnetoreception of the light-dependent magnetic compass in birds is suggested to be mediated by a radical-pair mechanism taking place in the avian retina. Biophysical models on magnetic field effects on radical pairs generally assume that the light activating the magnetoreceptor molecules is nondirectional and unpolarized, and that light absorption is isotropic. However, natural skylight enters the avian retina unidirectionally, through the cornea and the lens, and is often partially polarized. In addition, cryptochromes, the putative magnetoreceptor molecules, absorb light anisotropically, i.e., they preferentially absorb light of a specific direction and polarization, implying that the light-dependent magnetic compass is intrinsically polarization sensitive. To test putative interactions between the avian magnetic compass and polarized light, we developed a spatial orientation assay and trained zebra finches to magnetic and/or overhead polarized light cues in a four-arm “plus” maze. The birds did not use overhead polarized light near the zenith for sky compass orientation. Instead, overhead polarized light modulated light-dependent magnetic compass orientation, i.e., how the birds perceive the magnetic field. Birds were well oriented when tested with the polarized light axis aligned parallel to the magnetic field. When the polarized light axis was aligned perpendicular to the magnetic field, the birds became disoriented. These findings are the first behavioral evidence to our knowledge for a direct interaction between polarized light and the light-dependent magnetic compass in an animal. They reveal a fundamentally new property of the radical pair-based magnetoreceptor with key implications for how birds and other animals perceive the Earth’s magnetic field.

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