Model calculations of magnetic field effects on the recombination reactions of radicals with anisotropic hyperfine interactions

Timmel, Christiane R.; Cintolesi, F.; Brocklehurst, B.; Hore, P. J.

doi:10.1016/s0009-2614(00)01436-6

Cited by 57 publications

(64 citation statements)

References 24 publications

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“…This suggestion has been confirmed by numerical simulations (2,33,(43)(44)(45). Anisotropic magnetic field effects arising from hyperfine interactions have recently been observed experimentally (14).…”

supporting

confidence: 55%

“…In the context of radical pair magnetoreception, this unusual property could be related to the field-dependent changes in S 7 T interconversion that are known to arise from energy-level degeneracies (44). As an example, simulations are shown in the SI Appendix that reveal a strong dependence of the form and amplitude of the reaction yield anisotropy on the magnetic field intensity in the range 10-100 T (66).…”

Section: Evidence For Radical Pair Magnetoreceptionmentioning

confidence: 99%

“…A number of quantitative theoretical studies, most of which have been mentioned above, have tested selected aspects of the radical pair mechanism (2,33,43,44,57,58,66,80). However, for the most part, disorder, motion and spin relaxation have all been ignored.…”

Section: Evidence For Radical Pair Magnetoreceptionmentioning

confidence: 99%

“…Numerical simulations generally support the idea of a radical-pair-based compass and have shed some light on the conditions required for significant reaction yield anisotropies. In favorable cases, the orientational dependence is usually no more than a Ϸ50% variation in the reaction yield (43,44,58). Under more realistic conditions, changes of 1-10% seem more likely.…”

Section: Evidence For Radical Pair Magnetoreceptionmentioning

confidence: 99%

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Chemical magnetoreception in birds: The radical pair mechanism

Rodgers

Hore²

2009

Proc. Natl. Acad. Sci. U.S.A.

466

449

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Migratory birds travel vast distances each year, finding their way by various means, including a remarkable ability to perceive the Earth's magnetic field. Although it has been known for 40 years that birds possess a magnetic compass, avian magnetoreception is poorly understood at all levels from the primary biophysical detection events, signal transduction pathways and neurophysiology, to the processing of information in the brain. It has been proposed that the primary detector is a specialized ocular photoreceptor that plays host to magnetically sensitive photochemical reactions having radical pairs as fleeting intermediates. Here, we present a physical chemist's perspective on the ''radical pair mechanism'' of compass magnetoreception in birds. We outline the essential chemical requirements for detecting the direction of an Earth-strength Ϸ50 T magnetic field and comment on the likelihood that these might be satisfied in a biologically plausible receptor. Our survey concludes with a discussion of cryptochrome, the photoactive protein that has been put forward as the magnetoreceptor molecule.

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supporting

confidence: 55%

Section: Evidence For Radical Pair Magnetoreceptionmentioning

confidence: 99%

Section: Evidence For Radical Pair Magnetoreceptionmentioning

confidence: 99%

Section: Evidence For Radical Pair Magnetoreceptionmentioning

confidence: 99%

See 2 more Smart Citations

Chemical magnetoreception in birds: The radical pair mechanism

Rodgers

Hore²

2009

Proc. Natl. Acad. Sci. U.S.A.

466

449

View full text Add to dashboard Cite

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“…A crucial element in all such calculations is the presence of nuclear spins whose hyperfine interactions are the source of the magnetic anisotropy (8,16). Most studies have focused on idealized spin systems comprising the two electron spins, one on each radical, augmented by one or two nuclear spins (9,(21)(22)(23)(24)(25)(26)(27)34). Only a handful has attempted to deal with realistic, multinuclear radical pairs (10,16,17,20).…”

mentioning

confidence: 99%

The quantum needle of the avian magnetic compass

Hiscock

Worster

Kattnig

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

163

223

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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. magnetic compass | magnetoreception | migratory birds | quantum biology | radical pair mechanism M igratory birds have a light-dependent magnetic compass (1-4). The primary sensory receptors are located in the eyes (2, 3, 5-7), and directional information is processed bilaterally in a small part of the forebrain accessed via the thalamofugal visual pathway. The evidence currently points to a chemical sensing mechanism based on photo-induced radical pairs in cryptochrome flavoproteins in the retina (8-18). Anisotropic magnetic interactions within the radicals are thought to give rise to intracellular levels of a cryptochrome signaling state that depend on the orientation of the bird's head in the Earth's magnetic field (8,9,19). In support of this proposal, the photochemistry of isolated cryptochromes in vitro has been found to respond to applied magnetic fields in a manner that is quantitatively consistent with the radical pair mechanism (15). Aspects of the radical pair hypothesis have also been explored in a number of theoretical studies, the majority of which have concentrated on the magnitude of the anisotropic magnetic field effect (9,10,16,17,(19)(20)(21)(22)(23)(24)(25)(26)(27). Very little attention has been devoted to the matter we address here: the precision of the compass bearing available from a radical pair sensor (28).To migrate successfully over large distances, it is not sufficient simply to distinguish north from south (or poleward from equatorward) (29). A bar-tailed godwit (Limosa lapponica baueri), for example, was tracked by satellite flying from Alaska to New Zealand in a single 11,000-km nonstop flight across the Pacific Ocean (30). A directional error of more than a few degre...

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Laser Flash Photolysis of Photoinitiators: ESR, Optical, and IR Spectroscopy Detection of Transients

Khudyakov¹,

Turro

2009

Carbon‐Centered Free Radicals and Radical Cations

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Model calculations of magnetic field effects on the recombination reactions of radicals with anisotropic hyperfine interactions

Cited by 57 publications

References 24 publications

Chemical magnetoreception in birds: The radical pair mechanism

Chemical magnetoreception in birds: The radical pair mechanism

The quantum needle of the avian magnetic compass

Laser Flash Photolysis of Photoinitiators: ESR, Optical, and IR Spectroscopy Detection of Transients

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