scholarly journals Radical pairs can explain magnetic field and lithium effects on the circadian clock

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Hadi Zadeh-Haghighi ◽  
Christoph Simon

AbstractDrosophila’s circadian clock can be perturbed by magnetic fields, as well as by lithium administration. Cryptochromes are critical for the circadian clock. Further, the radical pairs in cryptochrome also can explain magnetoreception in animals. Based on a simple radical pair mechanism model of the animal magnetic compass, we show that both magnetic fields and lithium can influence the spin dynamics of the naturally occurring radical pairs and hence modulate the circadian clock’s rhythms. Using a simple chemical oscillator model for the circadian clock, we show that the spin dynamics influence a rate in the chemical oscillator model, which translates into a change in the circadian period. Our model can reproduce the results of two independent experiments, magnetic field and lithium effects on the circadian clock. Our model predicts that stronger magnetic fields would shorten the clock’s period. We also predict that lithium influences the clock in an isotope-dependent manner. Furthermore, our model also predicts that magnetic fields and hyperfine interactions modulate oxidative stress. The findings of this work suggest that the quantum nature of radical pairs might play roles in the brain, as another piece of evidence in addition to recent results on xenon anesthesia and lithium effects on hyperactivity.

2021 ◽  
Author(s):  
Hadi Zadeh-Haghighi ◽  
Christoph Simon

Drosophila's circadian clock can be perturbed by magnetic fields, as well as by lithium administration. Cryptochromes are critical for the circadian clock. Further, the radical pairs in cryptochrome also can explain magnetoreception in animals. Based on a simple radical pair mechanism model of the animal magnetic compass, we show that both magnetic fields and lithium can influence the spin dynamics of the naturally occurring radical pairs and hence modulate the circadian clock's rhythms. Using a simple chemical oscillator model for the circadian clock, we show that the spin dynamics influence a rate in the chemical oscillator model, which translates into a change in the circadian period. Our model can reproduce the results of two independent experiments, magnetic fields and lithium effects on the circadian clock. Our model predicts that stronger magnetic fields would shorten the clock's period. We also predict that lithium influences the clock in an isotope-dependent manner. Furthermore, our model also predicts that magnetic fields and hyperfine interactions modulate oxidative stress. The findings of this work suggest that quantum nature and entanglement of radical pairs might play roles in the brain, as another piece of evidence in addition to recent results on xenon anesthesia and lithium effects on hyperactivity.


2009 ◽  
Vol 37 (2) ◽  
pp. 358-362 ◽  
Author(s):  
Jonathan R. Woodward ◽  
Timothy J. Foster ◽  
Alex R. Jones ◽  
Adrian T. Salaoru ◽  
Nigel S. Scrutton

The effect of magnetic fields on chemical reactions through the RP (radical pair) mechanism is well established, but there are few examples, in the literature, of biological reactions that proceed through RP intermediates and show magnetic field-sensitivity. The present and future relevance of magnetic field effects in biological reactions is discussed.


2021 ◽  
Author(s):  
Hadi ZADEH-HAGHIGHI ◽  
Christoph Simon

The exact mechanism behind general anesthesia remains an open question in neuroscience. It has been proposed that anesthetics selectively prevent consciousness and memory via acting on microtubules (MTs). It is known that the magnetic field modulates MT organization. A recent study shows that a radical pair model can explain the isotope effect in xenon-induced anesthesia and predicts magnetic field effects on anesthetic potency. Further, reactive oxygen species are also implicated in MT stability and anesthesia. Based on a simple radical pair mechanism model and a simple mathematical model of MT organization, we show that magnetic fields can modulate spin dynamics of naturally occurring radical pairs in MT. We show that the spin dynamics influence a rate in the reaction cycle, which translates into a change in the MT density. We can reproduce magnetic field effects on the MT concentration that have been observed. Our model also predicts additional effects at slightly higher fields. Our model further predicts that the effect of zinc on the MT density exhibits isotopic dependence. The findings of this work make a connection between microtubule-based and radical pair-based quantum theories of consciousness.


2018 ◽  
Author(s):  
P. J. Hore

AbstractProlonged 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.


eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
PJ Hore

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.


2015 ◽  
Vol 233-234 ◽  
pp. 113-116
Author(s):  
Eleonora A. Kravchenko

209Bi NQR experiments, including analysis of zero-field line shapes, Zeeman-perturbed patterns and zero-field spin-echo envelopes were made to examine magnetic splitting of resonances revealed in the spectra of Main group element compounds of general composition BakBilAmOn (A=Al, В, Ge, Br, Cl). The results were explained assuming the existence in the compounds of ordered internal magnetic fields from 5 to 250 G which notably exceed those of nuclear magnetic moments. A dramatic (8−10-fold) increase in the resonance intensities, instead of broadening and fading, was observed for such compounds upon applying weak (below 500 Oe) external magnetic fields. The effect was shown to relate to the spin dynamics, namely, to the influence of external magnetic field on the nuclear spin-spin relaxation of the compounds with anomalous magnetic properties. In α-Bi2O3, paramagnetism depending on the thermal prehistory of a sample was found using SQUID-technique; magnetoelectric effect linear in magnetic field was also observed for this oxide.


2014 ◽  
Vol 11 (95) ◽  
pp. 20131063 ◽  
Author(s):  
Alpha A. Lee ◽  
Jason C. S. Lau ◽  
Hannah J. Hogben ◽  
Till Biskup ◽  
Daniel R. Kattnig ◽  
...  

There is growing evidence that the remarkable ability of animals, in particular birds, to sense the direction of the Earth's magnetic field relies on magnetically sensitive photochemical reactions of the protein cryptochrome. It is generally assumed that the magnetic field acts on the radical pair [FAD •− TrpH • + ] formed by the transfer of an electron from a group of three tryptophan residues to the photo-excited flavin adenine dinucleotide cofactor within the protein. Here, we examine the suitability of an [FAD •− Z • ] radical pair as a compass magnetoreceptor, where Z • is a radical in which the electron spin has no hyperfine interactions with magnetic nuclei, such as hydrogen and nitrogen. Quantum spin dynamics simulations of the reactivity of [FAD •− Z • ] show that it is two orders of magnitude more sensitive to the direction of the geomagnetic field than is [FAD •− TrpH • + ] under the same conditions (50 µT magnetic field, 1 µs radical lifetime). The favourable magnetic properties of [FAD •− Z • ] arise from the asymmetric distribution of hyperfine interactions among the two radicals and the near-optimal magnetic properties of the flavin radical. We close by discussing the identity of Z • and possible routes for its formation as part of a spin-correlated radical pair with an FAD radical in cryptochrome.


2015 ◽  
Vol 12 (103) ◽  
pp. 20141155 ◽  
Author(s):  
Hanan L. Messiha ◽  
Thanyaporn Wongnate ◽  
Pimchai Chaiyen ◽  
Alex R. Jones ◽  
Nigel S. Scrutton

Environmental exposure to electromagnetic fields is potentially carcinogenic. The radical pair mechanism is considered the most feasible mechanism of interaction between weak magnetic fields encountered in our environment and biochemical systems. Radicals are abundant in biology, both as free radicals and reaction intermediates in enzyme mechanisms. The catalytic cycles of some flavin-dependent enzymes are either known or potentially involve radical pairs. Here, we have investigated the magnetic field sensitivity of a number of flavoenzymes with important cellular roles. We also investigated the magnetic field sensitivity of a model system involving stepwise reduction of a flavin analogue by a nicotinamide analogue—a reaction known to proceed via a radical pair. Under the experimental conditions used, magnetic field sensitivity was not observed in the reaction kinetics from stopped-flow measurements in any of the systems studied. Although widely implicated in radical pair chemistry, we conclude that thermally driven, flavoenzyme-catalysed reactions are unlikely to be influenced by exposure to external magnetic fields.


2019 ◽  
Vol 116 (7) ◽  
pp. 2512-2520 ◽  
Author(s):  
Pablo R. Zangara ◽  
Siddharth Dhomkar ◽  
Ashok Ajoy ◽  
Kristina Liu ◽  
Raffi Nazaryan ◽  
...  

A broad effort is underway to improve the sensitivity of NMR through the use of dynamic nuclear polarization. Nitrogen vacancy (NV) centers in diamond offer an appealing platform because these paramagnetic defects can be optically polarized efficiently at room temperature. However, work thus far has been mainly limited to single crystals, because most polarization transfer protocols are sensitive to misalignment between the NV and magnetic field axes. Here we study the spin dynamics of NV−13C pairs in the simultaneous presence of optical excitation and microwave frequency sweeps at low magnetic fields. We show that a subtle interplay between illumination intensity, frequency sweep rate, and hyperfine coupling strength leads to efficient, sweep-direction-dependent 13C spin polarization over a broad range of orientations of the magnetic field. In particular, our results strongly suggest that finely tuned, moderately coupled nuclear spins are key to the hyperpolarization process, which makes this mechanism distinct from other known dynamic polarization channels. These findings pave the route to applications where powders are intrinsically advantageous, including the hyperpolarization of target fluids in contact with the diamond surface or the use of hyperpolarized particles as contrast agents for in vivo imaging.


Sign in / Sign up

Export Citation Format

Share Document