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Solov'yov, I. A., & Schulten, K. (2009). Magnetoreception through cryptochrome may involve superoxide. Biophys J, 96(12), 4804–4813.
Abstract: In the last decades, it has been demonstrated that many animal species orient in the Earth magnetic field. One of the best-studied examples is the use of the geomagnetic field by migratory birds for orientation and navigation. However, the biophysical mechanism underlying animal magnetoreception is still not understood. One theory for magnetoreception in birds invokes the so-called radical-pair model. This mechanism involves a pair of reactive radicals, whose chemical fate can be influenced by the orientation with respect to the magnetic field of the Earth through Zeeman and hyperfine interactions. The fact that the geomagnetic field is weak, i.e., approximately 0.5 G, puts a severe constraint on the radical pair that can establish the magnetic compass sense. For a noticeable change of the reaction yield in a redirected geomagnetic field, the hyperfine interaction has to be as weak as the Earth field Zeeman interaction, i.e., unusually weak for an organic compound. Such weak hyperfine interaction can be achieved if one of the radicals is completely devoid of this interaction as realized in a radical pair containing an oxygen molecule as one of the radicals. Accordingly, we investigate here a possible radical pair-based reaction in the photoreceptor cryptochrome that reduces the protein's flavin group from its signaling state FADH* to the inactive state FADH- (which reacts to the likewise inactive FAD) by means of the superoxide radical, O2*-. We argue that the spin dynamics in the suggested reaction can act as a geomagnetic compass and that the very low physiological concentration (nM-microM) of otherwise toxic O2*- is sufficient, even favorable, for the biological function.
Keywords: Cryptochromes; Flavin-Adenine Dinucleotide/chemistry; Flavoproteins/*chemistry; Light; *Magnetics; Photochemical Processes; Superoxides/*chemistry
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Maeda, K., Robinson, A. J., Henbest, K. B., Hogben, H. J., Biskup, T., Ahmad, M., et al. (2012). Magnetically sensitive light-induced reactions in cryptochrome are consistent with its proposed role as a magnetoreceptor. Proceedings of the National Academy of Sciences, 109(13), 4774–4779.
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Remondini, D., Nylund, R., Reivinen, J., Poulletier de Gannes, F., Veyret, B., Lagroye, I., et al. (2006). Gene expression changes in human cells after exposure to mobile phone microwaves. Proteomics, 6(17), 4745–4754.
Abstract: Possible biological effects of mobile phone microwaves were investigated in vitro. In this study, which was part of the 5FP EU project REFLEX (Risk Evaluation of Potential Environmental Hazards From Low-Energy Electromagnetic Field Exposure Using Sensitive in vitro Methods), six human cell types, immortalized cell lines and primary cells, were exposed to 900 and 1800 MHz. RNA was isolated from exposed and sham-exposed cells and labeled for transcriptome analysis on whole-genome cDNA arrays. The results were evaluated statistically using bioinformatics techniques and examined for biological relevance with the help of different databases. NB69 neuroblastoma cells, T lymphocytes, and CHME5 microglial cells did not show significant changes in gene expression. In EA.hy926 endothelial cells, U937 lymphoblastoma cells, and HL-60 leukemia cells we found between 12 and 34 up- or down-regulated genes. Analysis of the affected gene families does not point towards a stress response. However, following microwave exposure, some but not all human cells might react with an increase in expression of genes encoding ribosomal proteins and therefore up-regulating the cellular metabolism.
Keywords: Cell Line; *Cellular Phone; Down-Regulation/*radiation effects; Humans; *Microwaves; Up-Regulation/*radiation effects
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Hosking, F. J., Papaemmanuil, E., Sheridan, E., Kinsey, S. E., Lightfoot, T., Roman, E., et al. (2010). Genome-wide homozygosity signatures and childhood acute lymphoblastic leukemia risk. Blood, 115(22), 4472–4477.
Abstract: Recent studies have reported that regions of homozygosity (ROH) in the genome are detectable in outbred populations and can be associated with an increased risk of malignancy. To examine whether homozygosity is associated with an increased risk of developing childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL), we analyzed 824 ALL cases and 2398 controls genotyped for 292 200 tagging SNPs. Across the genome, cumulative distribution of ROH was not significantly different between cases and controls. Four common ROH at 10p11.2-10q11.21, 1p31.1, 19p13.2-3, and 20q11.1-23 were, however, associated with ALL risk at P less than .01 (including 1 ROH to which the erythropoietin receptor [EPOR] gene maps, P = .005) but were nonsignificant after adjusting for multiple testing. Our findings make it unlikely that levels of measured homozygosity, caused by autozygosity, uniparental isodisomy, or hemizygosity, play a major role in defining BCP-ALL risk in predominantly outbred populations.
Keywords: Case-Control Studies; Child; Child, Preschool; Chromosome Mapping; European Continental Ancestry Group/genetics; Female; Genes, Recessive; Genome-Wide Association Study; Great Britain; *Homozygote; Humans; Infant; Male; Polymorphism, Single Nucleotide; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma/*genetics; Receptors, Erythropoietin/genetics; Risk Factors
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Fedele, G., Green, E. W., Rosato, E., & Kyriacou, C. P. (2014). An electromagnetic field disrupts negative geotaxis in Drosophila via a CRY-dependent pathway. Nature communications, 5, 4391.
Abstract: Many higher animals have evolved the ability to use the Earth's magnetic field, particularly for orientation. Drosophila melanogaster also respond to electromagnetic fields (EMFs), although the reported effects are quite modest. Here we report that negative geotaxis in flies, scored as climbing, is disrupted by a static EMF, and this is mediated by cryptochrome (CRY), the blue-light circadian photoreceptor. CRYs may sense EMFs via formation of radical pairs of electrons requiring photoactivation of flavin adenine dinucleotide (FAD) bound near a triad of Trp residues, but mutation of the terminal Trp in the triad maintains EMF responsiveness in climbing. In contrast, deletion of the CRY C terminus disrupts EMF responses, indicating that it plays an important signalling role. CRY expression in a subset of clock neurons, or the photoreceptors, or the antennae, is sufficient to mediate negative geotaxis and EMF sensitivity. Climbing therefore provides a robust and reliable phenotype for studying EMF responses in Drosophila.
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