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Brian K Taylor
Diverse taxa use Earth's magnetic field in conjunction with other sensory modalities to accomplish navigation tasks ranging from local homing to long-distance migration across continents and ocean basins. However, despite extensive research, the mechanisms that underlie animal magnetoreception are not clearly understood, and how animals use Earth's magnetic field to navigate is an active area of investigation. Concurrently, Earth's magnetic field offers a signal that engineered systems can leverage for navigation in environments where man-made systems such as GPS are unavailable or unreliable...
May 15, 2018: Bioinspiration & Biomimetics
Yunshan Cao, Peng Yan
It is a well established notion that animals can detect the Earth's magnetic field, while the biophysical origin of such magnetoreception is still elusive. Recently, a magnetic receptor Drosophila CG8198 (MagR) with a rodlike protein complex is reported [S. Qin et al., Nat. Mater. 15, 217 (2016)10.1038/nmat4484] to act like a compass needle to guide the magnetic orientation of animals. This view, however, is challenged [M. Meister, Elife 5, e17210 (2016)10.7554/eLife.17210] by arguing that thermal fluctuations beat the Zeeman coupling of the proteins's magnetic moment with the rather weak geomagnetic field (∼25-65 μT)...
April 2018: Physical Review. E
Andres Vidal-Gadea, Chance Bainbridge, Ben Clites, Bridgitte E Palacios, Layla Bakhtiari, Vernita Gordon, Jonathan Pierce-Shimomura
Many animals can orient using the earth's magnetic field. In a recent study, we performed three distinct behavioral assays providing evidence that the nematode Caenorhabditis elegans orients to earth-strength magnetic fields (<xref ref-type="bibr" rid="bib28">Vidal-Gadea et al., 2015</xref>). A new study by Landler et al. suggests that C. elegans does not orient to magnetic fields (<xref ref-type="bibr" rid="bib10">Landler et al., 2018</xref>)...
April 13, 2018: ELife
Atticus Pinzon-Rodriguez, Staffan Bensch, Rachel Muheim
The light-dependent magnetic compass of birds provides orientation information about the spatial alignment of the geomagnetic field. It is proposed to be located in the avian retina, and be mediated by a light-induced, biochemical radical-pair mechanism involving cryptochromes as putative receptor molecules. At the same time, cryptochromes are known for their role in the negative feedback loop in the circadian clock. We measured gene expression of Cry1, Cry2 and Cry4 in the retina, muscle and brain of zebra finches over the circadian day to assess whether they showed any circadian rhythmicity...
March 2018: Journal of the Royal Society, Interface
Wei Lin, Wensi Zhang, Xiang Zhao, Andrew P Roberts, Greig A Paterson, Dennis A Bazylinski, Yongxin Pan
The origin and evolution of magnetoreception, which in diverse prokaryotes and protozoa is known as magnetotaxis and enables these microorganisms to detect Earth's magnetic field for orientation and navigation, is not well understood in evolutionary biology. The only known prokaryotes capable of sensing the geomagnetic field are magnetotactic bacteria (MTB), motile microorganisms that biomineralize intracellular, membrane-bounded magnetic single-domain crystals of either magnetite (Fe3 O4 ) or greigite (Fe3 S4 ) called magnetosomes...
March 26, 2018: ISME Journal
Martin L Pall
Repeated Wi-Fi studies show that Wi-Fi causes oxidative stress, sperm/testicular damage, neuropsychiatric effects including EEG changes, apoptosis, cellular DNA damage, endocrine changes, and calcium overload. Each of these effects are also caused by exposures to other microwave frequency EMFs, with each such effect being documented in from 10 to 16 reviews. Therefore, each of these seven EMF effects are established effects of Wi-Fi and of other microwave frequency EMFs. Each of these seven is also produced by downstream effects of the main action of such EMFs, voltage-gated calcium channel (VGCC) activation...
March 21, 2018: Environmental Research
Rugang Geng, Ram C Subedi, Hoang M Luong, Minh T Pham, Weichuan Huang, Xiaoguang Li, Kunlun Hong, Ming Shao, Kai Xiao, Lawrence A Hornak, Tho D Nguyen
Hyperfine interaction (HFI), originating from the coupling between spins of charge carriers and nuclei, has been demonstrated to strongly influence the spin dynamics of localized charges in organic semiconductors. Nevertheless, the role of charge localization on the HFI strength in organic thin films has not yet been experimentally investigated. In this study, the statistical relation hypothesis that the effective HFI of holes in regioregular poly(3-hexylthiophene) (P3HT) is proportional to 1/N^{0.5} has been examined, where N is the number of the random nuclear spins within the envelope of the hole wave function...
February 23, 2018: Physical Review Letters
Sandra Malewski, E Pascal Malkemper, František Sedláček, Radim Šumbera, Kai R Caspar, Hynek Burda, Sabine Begall
Magnetosensitivity is widespread among animals with rodents being the most intensively studied mammalian group. The available behavioural assays for magnetoreception are time-consuming, which impedes screens for treatment effects that could characterize the enigmatic magnetoreceptors. Here, we present a fast and simple approach to test if an animal responds to magnetic stimuli: the magnetic object assay (MOA). The MOA focuses on investigating an animal's spontaneous exploration behaviour in the presence of a bar magnet compared to a demagnetised control...
June 2018: Behavioural Processes
Jacques Vanderstraeten, Philippe Gailly, E Pascal Malkemper
Various responses to static magnetic fields (MF) have been reported in plants, and it has been suggested that the geomagnetic field influences plant physiology. Accordingly, diverse mechanisms have been proposed to mediate MF effects in plants. The currently most probable sensor candidates are cryptochromes (Cry) which are sensitive to submillitesla MF. Here, we propose a quantitative approach of the MF effect on Cry depending on light intensity, and try to link it to a possible functional role for magnetic sensitivity in plants...
2018: Frontiers in Plant Science
Ahne Myklatun, Antonella Lauri, Stephan H K Eder, Michele Cappetta, Denis Shcherbakov, Wolfgang Wurst, Michael Winklhofer, Gil G Westmeyer
An impediment to a mechanistic understanding of how some species sense the geomagnetic field ("magnetoreception") is the lack of vertebrate genetic models that exhibit well-characterized magnetoreceptive behavior and are amenable to whole-brain analysis. We investigated the genetic model organisms zebrafish and medaka, whose young stages are transparent and optically accessible. In an unfamiliar environment, adult fish orient according to the directional change of a magnetic field even in darkness...
February 23, 2018: Nature Communications
David A Ernst, Kenneth J Lohmann
On a global scale, the geomagnetic field varies predictably across the Earth's surface, providing animals that migrate long distances with a reliable source of directional and positional information that can be used to guide their movements. In some locations, however, magnetic minerals in the Earth's crust generate an additional field that enhances or diminishes the overall field, resulting in unusually steep gradients of field intensity within a limited area. How animals respond to such magnetic anomalies is unclear...
March 1, 2018: Journal of Experimental Biology
S Krichen, L Liu, P Sharma
Sharks, birds, bats, turtles, and many other animals can detect magnetic fields. Aside from using this remarkable ability to exploit the terrestrial magnetic field map to sense direction, a subset is also able to implement a version of the so-called geophysical positioning system. How do these animals detect magnetic fields? The answer to this rather deceptively simple question has proven to be quite elusive. The currently prevalent theories, while providing interesting insights, fall short of explaining several aspects of magnetoreception...
October 2017: Physical Review. E
Adriano Barreto Nogueira, Ariel Barreto Nogueira, José Carlos Esteves Veiga, Manoel Jacobsen Teixeira
We have recently found that the temperature variability (TV) in the day-night cycle may predict the mean intracranial pressure in the following 24 h (ICP24 ) in subarachnoid hemorrhage (SAH) patients under multimodality monitoring, sedation, and hypothermia (<35°C). Specifically, we found that ICP24  = 6 (4 - TV) mmHg. TV is the ratio between the coefficient of variation of temperature during the nocturnal and the preceding diurnal periods. This result suggests that the circadian clock reflects brain plasticity mechanisms and its malfunctioning leads to deterioration of the neurologic status...
2017: Frontiers in Neurology
Ida Friis, Emil Sjulstok, Ilia A Solov'yov
Birds use the magnetic field of the Earth to navigate during their annual migratory travel. The possible mechanism to explain the biophysics of this compass sense involves electron transfers within the photoreceptive protein cryptochrome. The magnetoreceptive functioning of cryptochromes is supposedly facilitated through an iron rich polymer complex which couples to multiple cryptochromes. The present investigation aims to independently reconstruct this complex and describe its interaction with Drosophila melanogaster cryptochromes...
October 24, 2017: Scientific Reports
Jing-Jing Xu, Ying-Chao Zhang, Jian-Qi Wu, Wei-Hong Wang, Yue Li, Gui-Jun Wan, Fa-Jun Chen, Gregory A Sword, Wei-Dong Pan
The mechanisms of magnetoreception have been proposed as the magnetite-based, the chemical radical-pair and biocompass model, in which magnetite particles, the cryptochrome (Cry) or iron-sulfur cluster assembly 1 (IscA1) may be involved. However, little is known about the association among the molecules. Here we investigated the molecular characterization and the mRNA expression of IscA1 in different developmental stages, tissues and magnetic fields in the migratory brown planthopper (BPH), Nilaparvata lugens...
October 23, 2017: Insect Science
Gregory C Nordmann, Tobias Hochstoeger, David A Keays
Evolution has equipped life on our planet with an array of extraordinary senses, but perhaps the least understood is magnetoreception. Despite compelling behavioral evidence that this sense exists, the cells, molecules, and mechanisms that mediate sensory transduction remain unknown. So how could animals detect magnetic fields? We introduce and discuss 3 concepts that attempt to address this question: (1) a mechanically sensitive magnetite-based magnetoreceptor, (2) a light-sensitive chemical-based mechanism, and (3) electromagnetic induction within accessory structures...
October 2017: PLoS Biology
Min Jiang, Lujia Zhang, Fengqing Wang, Jie Zhang, Guosong Liu, Bei Gao, Dongzhi Wei
Recently, a magnetic protein was discovered, and a multimeric magnetosensing complex was validated, which may form the basis of magnetoreception. In this study, the magnetic protein was firstly used in biotechnology application, and a novel convenient one-step purification and immobilization method was established. A universal vector and three linker patterns were developed for fusion expression of magnetic protein and target protein. The magnetic protein was absorbed by iron beads, followed by target protein aggregation, purification, and immobilization...
October 17, 2017: Scientific Reports
Daniel R Kattnig
Birds and several other species are equipped with the remarkable ability to sense the geomagnetic field for the purpose of navigation and orientation. The primary detection mechanism of this compass sense is uncertain but appears to originate from a truly quantum process involving spin-correlated radical pairs. In order to elicit sensitivity to weak magnetic fields, such as the Earth's magnetic field, the underlying spin dynamics must be protected from fast decoherence. In this work, we elucidate the effects of spin relaxation on a recently suggested reaction scheme involving three radicals, instead of a radical pair, doublet-quartet interconversion under magnetic interactions, and a spin-selective scavenging reaction...
October 26, 2017: Journal of Physical Chemistry. B
Kwon-Seok Chae, Yong-Hwan Kim
Throughout the long history of various therapeutic trials of transcranial magnetic stimulation (TMS), some TMS protocols have been reported to be clearly effective in the treatment of neurodegenerative diseases. Despite promising results from repetitive TMS (rTMS) using low frequency electromagnetic fields (EMFs) for neurodegenerative diseases, the low reproducibility has hampered the clinical applications of rTMS. Here, based on the notion of radical pair mechanism explaining magnetoreception in living organisms, we propose a new perspective that rTMS with controlled geomagnetic field (rTMS-GMF) can be an efficient and reproducible therapeutic approach for neurodegenerative diseases...
2017: Frontiers in Human Neuroscience
Hamish G Hiscock, Henrik Mouritsen, David E Manolopoulos, P J Hore
The radical-pair mechanism has been put forward as the basis of the magnetic compass sense of migratory birds. Some of the strongest supporting evidence has come from behavioral experiments in which birds exposed to weak time-dependent magnetic fields lose their ability to orient in the geomagnetic field. However, conflicting results and skepticism about the requirement for abnormally long quantum coherence lifetimes have cast a shroud of uncertainty over these potentially pivotal studies. Using a recently developed computational approach, we explore the effects of various radiofrequency magnetic fields on biologically plausible radicals within the theoretical framework of radical-pair magnetoreception...
October 3, 2017: Biophysical Journal
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