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Plant Responses to Electromagnetic Fields
Published in Ben Greenebaum, Frank Barnes, Biological and Medical Aspects of Electromagnetic Fields, 2018
In plants, cryptochromes control different aspects of growth and development (Wang et al., 2014; Liu et al., 2016); i.e., involvement in de-etiolation responses such as inhibition of hypocotyl growth (Ahmad and Cashmore, 1993; Lin, 2002), anthocyanin accumulation (Ahmad et al., 1995), leaf and cotyledon expansion (Cashmore et al., 1999; Lin, 2002), transitions to flowering (El-Assal et al., 2003), or regulation of blue-light-regulated genes (Jiao et al., 2003). In Arabidopsis, cryptochromes are encoded by two similar genes, cry1 and cry2. CRY2 protein levels in seedlings decrease rapidly upon illumination by blue light, presumably as a result of protein degradation of the light-activated form of the receptor (Ahmad et al., 2007). Like photolyases, plant cryptochromes undergo a light-dependent electron transfer reaction, known as photoactivation, that leads to photoreduction of the flavin cofactor, FAD (Giovani et al., 2003).
Treatment Options for Chemical Sensitivity
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 5, 2017
William J. Rea, Kalpana D. Patel
Features of the circadian clock in all organisms include its persistence under constant conditions, a periodicity that is temperature compensated, and its entrainment to light from the sun. In mammals, cell autonomous circadian clocks are generated by a transcriptional autoregulatory feedback loop composed of the transcriptional activators, CLOCK and BMAL1, and their target genes, Period and Cryptochrome, which rhythmically accumulate and form a repressor complex that interacts with CLOCK-BMAL1, to inhibit their own transcription.72 This autoregulatory loop is posttranscriptionally regulated by casein kinases (CK1ε and CK1δ), which target the PER proteins for degradation via the SCF/β-TrCP–ubiquitin ligase complex, and by AMP kinase, which targets the CRY proteins for degradation via the SCF/FBXL3–ubiquitin ligase complex by the 26S proteosome (Figure 6.10).
Magnetoreception in Plants
Published in Shoogo Ueno, Tsukasa Shigemitsu, Bioelectromagnetism, 2022
Cryptochromes undergo forward light-induced reactions involving electron transfer to excited state flavin to generate radical intermediates, which correlate with biological activity. A mechanism for the reverse reaction, namely dark reoxidation of protein-bound flavin in Arabidopsis cryptochrome (AtCRY1) by molecular oxygen, involves the formation of a spin-correlated FADH-superoxide RP (Muller and Ahmad, 2011). Under conditions of illumination, the cryptochrome photoreceptors are constantly cycling between inactive (oxidized) and activated (reduced) redox states, such that the net biological activity results from the sum of the light-induced (activating) and reverse (de-activating) redox reactions at any given timepoint. A model of the cryptochrome photocycle incorporating these elements and an estimation of the quantum efficiency of redox state interconversions both in vitro and in vivo has been recently derived (Procopio et al., 2016). However, when light and dark intervals are given intermittently, the plant MFE is observed even when the MF is given exclusively during the dark intervals between light exposures. This indicates that the magnetically sensitive reaction step in the cryptochrome photocycle must occur during flavin reoxidation, and likely involves the formation of reactive oxygen species (Pooam et al., 2019). A recent model of MFE on the cryptochrome photocycle involves activation of cryptochrome by flavin reduction which triggers conformational change leading to unfolding and subsequent phosphorylation of the C-terminal domain. The flavin is subsequently reoxidized by reaction with molecular oxygen that occurs independently of light (Ahmad, 2016). The effect of an applied MF on the cryptochrome photocycle occurs during the period of flavin reoxidation. The most likely effect is to alter the rate constant of reoxidation of the reduced flavin intermediates, and thereby alter the lifetime of the activated state (Figure 5.11). As discussed above, theoretical considerations have argued against a flavin/superoxide radical pair, which is formed in the course of flavin reoxidation as the magnetosensing intermediate in cryptochromes (Hore and Mouritsen, 2016); however, cryptochrome localized within living cells is in contact with many cellular metabolites, which, moreover, can move into the flavin pocket in close association with the flavin cofactor. Therefore, the possibility of the third-party cellular factors participating in the formation of RPs during the process of cryptochrome flavin reoxidation cannot be excluded (Pooam et al., 2019). In sum, there are at least two reaction steps in the course of cryptochrome photocycle that could in principle be altered by the magnetic fields: the step of flavin photoreduction and that of flavin reoxidation. In either case, the effect of the magnetic field would be to alter cryptochrome biological activity by changing the rate of formation of the active state (forward reaction) or the rate of disappearance of the active state (reoxidation reaction) (Pooam et al., 2020a).
Studies on coherent and incoherent spin dynamics that control the magnetic field effect on photogenerated radical pairs
Published in Molecular Physics, 2020
Alternatively, there is a great possibility that the molecular dynamics can be quantitatively probed by observing the decoherence processes of radical pairs. Such an approach would help understanding complicated electron transfer mechanisms in biological and artificial systems. In the future, the mechanism of avian magnetoreception would be clarified by studying controlling mechanisms of the spin decoherence in avian cryptochrome with detailed analysis of experimental MFE by MD-assisted spin dynamics simulations. In the case of electron−hole pairs in organic semiconductor thin films, diffusion modelling based on the microscopic structures of the disordered organic solids and its combination with spin dynamics simulations would clarify the molecular-level mechanisms of charge extinction (mainly recombination) from electrically and/or optically detected MFE. Such studies would offer important feedback to development and engineering of these future materials.
Dynamics of flavin containing radical pairs in SDS micellar media probed by static and pulse magnetic field effect and pulse ADMR
Published in Molecular Physics, 2019
Recently, the attraction to the photochemistry of the flavin systems has been increased in connection with the flavin containing photoreceptor molecule such as phototropin, photolyase, and cryptochrome [16–18]. Since some experimental evidence suggests that the photochemical dynamics of flavins has been considered as the source of the magneto reception of animals and plants [17,19,20], the MFE on the dynamics of RP comprised of flavin has received various attentions [21–23]. Since the flavin derivatives have a mixed character of hydrophobic and hydrophilic, the association feature of them to the hydrophobic molecular system is rather complicated. Previously, we have reported a dependence of the association feature on the hydrophobic character of flavin derivatives by using MFE [24]. Addition to the hydrophobic nature, the Coulomb forces of the ionic structure of the molecules also have a great contribution to the association of the molecules [25,26]. We can think that such character is one of the essential problems of the spin related reaction dynamics in the biological environments [27–29].
Enhanced amylase production by a Bacillus subtilis strain under blue light-emitting diodes
Published in Preparative Biochemistry and Biotechnology, 2019
Punniyakotti Elumalai, Jeong-Muk Lim, Yool-Jin Park, Min Cho, Patrick J. Shea, Byung-Taek Oh
Light is important for maximum enzyme production; it governs propagation and growth of bacteria, metabolic activity and metabolite production, and functions through photoreceptors.[13,14] Classes of photoreceptors include cryptochrome, blue light sensing using flavin adenine dinucleotide (BLUF), light oxygen voltage (LOV), photoactive yellow protein (PYP), rhodopsin, and phytochrome. The non-phototrophic bacteria Bacillus subtilis, Deinococcus radiodurans, and Pseudomonas aeruginosa can sense light by the LOV photoreceptor and the BLUF blue-light sensing photoreceptor has been reported and characterized in B. subtilis.[15,16] BLUF and LOV are involved in the electron transfer mechanism.[17] BLUF is a positive regulator and stress transcription factor.[16] In sensing blue light, BLUF regulates and enhances pigment production, fruiting body formation, and encodes proteins with numerous conserved LOV domains.[13]