Reduction of geomagnetic field (GMF) to near null magnetic field (NNMF) affects some Arabidopsis thaliana clock genes amplitude in a light independent manner

Hypomagnetic Conditions and Their Biological Action (Review)

The geomagnetic field plays an important role in the existence of life on Earth. The study of the biological effects of (hypomagnetic conditions) HMC is an important task in magnetobiology. The fundamental importance is expanding and clarifying knowledge about the mechanisms of magnetic field interaction with living systems. The applied significance is improving the training of astronauts for long-term space expeditions. This review describes the effects of HMC on animals and plants, manifested at the cellular and organismal levels. General information is given about the probable mechanisms of HMC and geomagnetic field action on living systems. The main experimental approaches are described. We attempted to systematize quantitative data from various studies and identify general dependencies of the magnetobiology effects' value on HMC characteristics (induction, exposure duration) and the biological parameter under study. The most pronounced effects were found at the cellular level compared to the organismal level. Gene expression and protein activity appeared to be the most sensitive to HMC among the molecular cellular processes. The nervous system was found to be the most sensitive in the case of the organism level. The review may be of interest to biologists, physicians, physicists, and specialists in interdisciplinary fields.

Cryptochrome and quantum biology: unraveling the mysteries of plant magnetoreception

Magnetoreception, the remarkable ability of organisms to perceive and respond to Earth's magnetic field, has captivated scientists for decades, particularly within the field of quantum biology. In the plant science, the exploration of the complicated interplay between quantum phenomena and classical biology in the context of plant magnetoreception has emerged as an attractive area of research. This comprehensive review investigates into three prominent theoretical models: the Radical Pair Mechanism (RPM), the Level Crossing Mechanism (LCM), and the Magnetite-based MagR theory in plants. While examining the advantages, limitations, and challenges associated with each model, this review places a particular weight on the RPM, highlighting its well-established role of cryptochromes and in-vivo experiments on light-independent plant magnetoreception. However, alternative mechanisms such as the LCM and the MagR theory are objectively presented as convincing perspectives that permit further investigation. To shed light on these theoretical frameworks, this review proposes experimental approaches including cutting-edge experimental techniques. By integrating these approaches, a comprehensive understanding of the complex mechanisms driving plant magnetoreception can be achieved, lending support to the fundamental principle in the RPM. In conclusion, this review provides a panoramic overview of plant magnetoreception, highlighting the exciting potential of quantum biology in unraveling the mysteries of magnetoreception. As researchers embark on this captivating scientific journey, the doors to deciphering the diverse mechanisms of magnetoreception in plants stand wide open, offering a profound exploration of nature's adaptations to environmental cues.

14-3-3 Proteins and the Plasma Membrane H+-ATPase Are Involved in Maize (Zea mays) Magnetic Induction

The geomagnetic field (GMF) is a natural component of the biosphere, and, during evolution, all organisms experienced its presence while some evolved the ability to perceive magnetic fields (MF). We studied the response of 14-3-3 proteins and the plasma membrane (PM) proton pump H+-ATPase to reduced GMF values by lowering the GMF intensity to a near-null magnetic field (NNMF). Seedling morphology, H+-ATPase activity and content, 14-3-3 protein content, binding to PM and phosphorylation, gene expression, and ROS quantification were assessed in maize (Zea mays) dark-grown seedlings. Phytohormone and melatonin quantification were also assessed by LG-MS/MS. Our results suggest that the GMF regulates the PM H+-ATPase, and that NNMF conditions alter the proton pump activity by reducing the binding of 14-3-3 proteins. This effect was associated with both a reduction in H2O2 and downregulation of genes coding for enzymes involved in ROS production and scavenging, as well as calcium homeostasis. These early events were followed by the downregulation of IAA synthesis and gene expression and the increase in both cytokinin and ABA, which were associated with a reduction in root growth. The expression of the homolog of the MagR gene, ZmISCA2, paralleled that of CRY1, suggesting a possible role of ISCA in maize magnetic induction. Interestingly, melatonin, a widespread molecule present in many kingdoms, was increased by the GMF reduction, suggesting a still unknown role of this molecule in magnetoreception.

Effects of weak static magnetic fields on the development of seedlings of Arabidopsis thaliana

To study magnetoreception of Arabidopsis thaliana, we analysed several developmental responses including cryptochrome-independent seed germination and the phytochrome- and cryptochrome-dependent hypocotyl elongation and photo-accumulation of anthocyanins and chlorophylls in weak static magnetic fields ranging from near null to 122 μT. A field of 50 μT accelerated seed germination by about 20 h relative to samples maintained in a near-null field. The double mutant, cry1cry2, lacking cryptochromes 1 and 2 displayed the same magnetic field-induced germination acceleration under blue light as the wild-type strain. Magnetic field-induced germination acceleration was masked in the presence of exogenous sucrose. Stimulus-response curves for hypocotyl elongation in a range between near-null to 122 μT indicated maxima near 9 and 60 μT for the wild-type strain as well as mutant cry1cry2. The photo-accumulation of anthocyanins and chlorophylls could be effectively modulated by magnetic fields in the presence of low-irradiance red and blue light, respectively. The findings indicate that Arabidopsis thaliana possesses light-independent mechanisms of magnetic field reception, which remain presently unidentified. Our results are in better agreement with predictions of the level crossing mechanism (LCM) of magnetoreception rather than those of the cryptochrome-associated radical-pair mechanism (RPM).

The Geomagnetic Field (GMF) Is Required for Lima Bean Photosynthesis and Reactive Oxygen Species Production

Plants evolved in the presence of the Earth's magnetic field (or geomagnetic field, GMF). Variations in MF intensity and inclination are perceived by plants as an abiotic stress condition with responses at the genomic and metabolic level, with changes in growth and developmental processes. The reduction of GMF to near null magnetic field (NNMF) values by the use of a triaxial Helmholtz coils system was used to evaluate the requirement of the GMF for Lima bean (Phaseolus lunatus L.) photosynthesis and reactive oxygen species (ROS) production. The leaf area, stomatal density, chloroplast ultrastructure and some biochemical parameters including leaf carbohydrate, total carbon, protein content and δ¹³C were affected by NNMF conditions, as were the chlorophyll and carotenoid levels. RubisCO activity and content were also reduced in NNMF. The GMF was required for the reaction center's efficiency and for the reduction of quinones. NNMF conditions downregulated the expression of the MagR homologs PlIScA2 and PlcpIScA, implying a connection between magnetoreception and photosynthetic efficiency. Finally, we showed that the GMF induced a higher expression of genes involved in ROS production, with increased contents of both H₂O₂ and other peroxides. Our results show that, in Lima bean, the GMF is required for photosynthesis and that PlIScA2 and PlcpIScA may play a role in the modulation of MF-dependent responses of photosynthesis and plant oxidative stress.

Iron-sulfur complex assembly: Potential players of magnetic induction in plants

Iron-sulfur (Fe-S) clusters are involved in fundamental biological reactions and represent a highly regulated process involving a complex sequence of mitochondrial, cytosolic and nuclear-catalyzed protein-protein interactions. Iron-sulfur complex assembly (ISCA) scaffold proteins are involved in Fe-S cluster biosynthesis, nitrogen and sulfur metabolism. ISCA proteins are involved in abiotic stress responses and in the pigeon they act as a magnetic sensor by forming a magnetosensor (MagS) complex with cryptochrome (Cry). MagR gene exists in the genomes of humans, plants, and microorganisms and the interaction between Cry and MagR is highly conserved. Owing to the extensive presence of ISCA proteins in plants and the occurrence of homology between animal and human MagR with at least four Arabidopsis ISCAs and several ISCAs from different plant species, we believe that a mechanism similar to pigeon magnetoperception might be present in plants. We suggest that plant ISCA proteins, homologous of the animal MagR, are good candidates and could contribute to a better understanding of plant magnetic induction. We thus urge more studies in this regard to fully uncover the plant molecular mechanisms underlying MagR/Cry mediated magnetic induction and the possible coupling between light and magnetic induction.

Growth alteration of Allium cepa L. roots exposed to 1.5 mT, 25 Hz pulsed magnetic field

The response of plants to magnetic fields (MF) is not fully understood. This work studies the effects of pulsed MF on the germination and growth of Allium cepa roots. Onions were exposed to 25Hz, 1.5mT, 33h. Pulsed MF was generated by a Helmholtz-type equipment that generated rectangular voltage pulses. The results showed that fewer roots grew in the specimens exposed to pulsed MF (14±6 roots on day 1 to 21±8 on day 4) than in the control groups (32±17 to 48±23) (p<0.05 Friedman). Control specimens showed a root mean length of 7±4 mm (day 1) and 24±10 mm (day 4). The specimens treated with pulsed MF showed a length of 4±2 mm (day 1), reaching 18±9 mm on day 4 (p<0.001 ANOVA). In conclusion, the exposure of Allium cepa specimens to 25Hz, 1.5mT pulsed MF during 33h produces a decrease in the germination and growth of roots.

Influence of hypomagnetic field on the heartbeat in zebrafish embryos

The magnetic environment may influence the functioning of the cardiovascular system. It was reported that low-frequency and static magnetic fields affect hemodynamics, heart rate, and heart rate variability in animals and humans. Moreover, recent data suggest that magnetic fields affect the circadian rhythms of physiological processes. The influence of the magnetic environment on heart functionating during early development has been studied insufficiently. We utilized transparent zebrafish embryos to evaluate the effect of the hypomagnetic field on the characteristics of cardiac function using a noninvasive optical approach based on photoplethysmographic microscopic imaging. The embryos were exposed to the geomagnetic and hypomagnetic fields from the second to the 116th hour post fertilization under a 16 h light/8 h dark cycle or constant illumination. The exposure of embryos to the hypomagnetic field in both lighting modes led to increased embryo mortality, the appearance of abnormal phenotypes, and a significant increase in the embryo’s heartbeat rate. The difference between maximal and minimal heartbeat intervals, maximal to minimal heartbeat intervals ratio, and the coefficient of variation of heartbeat rate were increased in the embryos exposed to the hypomagnetic field under constant illumination from 96 to 116 h post fertilization. The dynamics of heartbeat rate changes followed a circadian pattern in all studied groups except zebrafish exposed to the hypomagnetic field under constant illumination. The results demonstrate the importance of natural magnetic background for the early development of zebrafish. The possible mechanisms of observed effects are discussed.

Reliable reference genes for gene expression analyses under the hypomagnetic field in a migratory insect

Manipulating the hypomagnetic field (HMF), which is the absence or significant weakening (<5 μT) of the geomagnetic field (GMF), offers a unique tool to investigate magnetic field effects on organismal physiology, development, behavior and life history. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) has been utilized to study changes in gene expression associated with exposure to the HMF. However, selecting appropriate reference genes (RGs) with confirmed stable expression across environments for RT-qPCR is often underappreciated. Using three algorithms (BestKeeper, NormFinder, and GeNorm), we investigated the expression stability of eight candidate RGs when exposed to the HMF condition versus local GMF during developmental from juveniles to adults in the migratory insect pest, the brown planthopper Nilaparvata lugens. During the nymphal stage, RPL5 & α-TUB1, EF1-α & ARF1, RPL5 & AK, EF1-α & RPL5, and ARF1 & AK were suggested as the most stable RG sets in the 1st to 5th instars, respectively. For 1- to 3-day-old adults, AK & ARF1, AK & α-TUB1, AK & ARF1 and EF1-α & RPL5, AK & α-TUB1, AK & EF1-α were the optimal RG sets for macropterous and brachypterous females, respectively. ACT1 & RPL5, RPL5 & EF1-α, α-TUB1 & ACT1 and EF1-α & RPL5, ARF1 & ACT1, ACT1 & ARF1 were the optimal RG sets for macropterous and brachypterous males, respectively. These results will facilitate accurate gene expression analyses under the HMF in N. lugens. The verification approach illustrated in this study highlights the importance of identifying reliable RGs for future empirical studies of magnetobiology (including magnetoreception) that involve magnetic field intensity as a factor.

The influences and regulatory mechanisms of magnetic fields on circadian rhythms

A variety of devices used in daily life and biomedical field will generate magnetic fields with different parameters, raising concern about their influences on people's physiological functions. Multiple experimental works have been devoted to the influences of magnetic fields on circadian rhythms, yet the findings were not always consistent due to the differences in magnetic field parameters and experimental organisms. Also, clear regulatory mechanisms have not been found. By systematizing the major achievements in research on magnetic and circadian rhythms based on magnetic flux density and analyzing the potential mechanisms of the magnetic fields affecting circadian rhythms, this review sheds light on the effects of magnetic fields on circadian rhythms and the potential applications in biomedicine.

Magnetic Fluctuations Entrain the Circadian Rhythm of Locomotor Activity in Zebrafish: Can Cryptochrome Be Involved?

Simple Summary

Most physiological processes are subject to biological circadian rhythms maintained by a complex cascade of biochemical events. The circadian rhythmicity of behavior allows organisms to use energy and resources optimally under changing environmental conditions. To that end, endogenous circadian rhythms are synchronized with external pacemakers (zeitgebers), especially daily changes in illumination. In the 1960s, it was assumed that, in addition to this primary photic cue, animals can use diurnal geomagnetic variation as a secondary zeitgeber. Earlier research found that slow magnetic fluctuations can affect some behavioral endpoints of circadian rhythms by modulating an organism’s physiological state. However, no direct experiments to test such an entrainment of biological clocks by artificial magnetic fields were performed due to the technical difficulty of eliminating natural geomagnetic variation. For the first time, we carried out such tests in a fully controlled magnetic environment using zebrafish as a research model. The experimental treatments included various light/dark cycles and continuous illumination coupled with pre-recorded natural geomagnetic variations. The obtained results indicate that slow magnetic fluctuations can entrain endogenous rhythmical activity in vertebrates. Probably, cryptochromes play a key role in this process. This research provides promising opportunities for the magnetic control of circadian processes, e.g., correcting circadian dysfunctions.

Abstract

In the 1960s, it was hypothesized that slow magnetic fluctuations could be a secondary zeitgeber for biological circadian rhythms. However, no comprehensive experimental research has been carried out to test the entrainment of free-running circadian rhythms by this zeitgeber. We studied the circadian patterns of the locomotor activity of zebrafish (Danio rerio) under different combinations of light regimes and slow magnetic fluctuations, based on a record of natural geomagnetic variation. A rapid synchronization of activity rhythms to an unusual 24:12 light/dark cycle was found under magnetic fluctuations with a period of 36 h. Under constant illumination, significant locomotor activity rhythms with 26.17 h and 33.07 h periods were registered in zebrafish exposed to magnetic fluctuations of 26.8 h and 33.76 h, respectively. The results reveal the potential of magnetic fluctuations for entrainment of circadian rhythms in zebrafish and genuine prospects to manipulate circadian oscillators via magnetic fields. The putative mechanisms responsible for the entrainment are discussed, including the possible role of cryptochromes.

Theoretical Concepts in Magnetobiology after 40 Years of Research

This review contains information on the development of magnetic biology, one of the multidisciplinary areas of biophysics. The main historical facts are presented and the general observed properties of magnetobiological phenomena are listed. The unavoidable presence of nonspecific magnetobiological effects in the everyday life of a person and society is shown. Particular attention is paid to the formation of theoretical concepts in magnetobiology and the state of the art in this area of research. Some details are provided on the molecular mechanisms of the nonspecific action of a magnetic field on organisms. The prospects of magnetobiology for the near and distant future are discussed.

Influence of Geomagnetic Disturbances at Different Times of Day on Locomotor Activity in Zebrafish (Danio Rerio)

The influence of magnetic fields and natural geomagnetic storms on biological circadian rhythms are actively studied. This study reveals an impact of local natural perturbations in the geomagnetic field that occurred at different times of the day on circadian patterns of locomotor activity of zebrafish. A decrease in zebrafish swimming speed was observed during the geomagnetic disturbances before or after the fluctuations of diurnal geomagnetic variation. However, if the geomagnetic perturbations coincided with the fluctuations of diurnal geomagnetic variation, the decrease in zebrafish swimming speed was insignificant. This result suggests that the biological effects of geomagnetic disturbances may depend on synchronization with the diurnal geomagnetic variation. It implies that the previously published correlations between geomagnetic activity and medical or biological parameters could result from a disruption in circadian biorhythms.

Differential root and shoot magnetoresponses in Arabidopsis thaliana

The geomagnetic field (GMF) is one of the environmental stimuli that plants experience continuously on Earth; however, the actions of the GMF on plants are poorly understood. Here, we carried out a time-course microarray experiment to identify genes that are differentially regulated by the GMF in shoot and roots. We also used qPCR to validate the activity of some genes selected from the microarray analysis in a dose-dependent magnetic field experiment. We found that the GMF regulated genes in both shoot and roots, suggesting that both organs can sense the GMF. However, 49% of the genes were regulated in a reverse direction in these organs, meaning that the resident signaling networks define the up- or downregulation of specific genes. The set of GMF-regulated genes strongly overlapped with various stress-responsive genes, implicating the involvement of one or more common signals, such as reactive oxygen species, in these responses. The biphasic dose response of GMF-responsive genes indicates a hormetic response of plants to the GMF. At present, no evidence exists to indicate any evolutionary advantage of plant adaptation to the GMF; however, plants can sense and respond to the GMF using the signaling networks involved in stress responses.

Circadian rhythms in zebrafish (Danio rerio) behaviour and the sources of their variability

Over recent decades, changes in zebrafish (Danio rerio) behaviour have become popular quantitative indicators in biomedical studies. The circadian rhythms of behavioural processes in zebrafish are known to enable effective utilization of energy and resources, therefore attracting interest in zebrafish as a research model. This review covers a variety of circadian behaviours in this species, including diurnal rhythms of spawning, feeding, locomotor activity, shoaling, light/dark preference, and vertical position preference. Changes in circadian activity during zebrafish ontogeny are reviewed, including ageing-related alterations and chemically induced variations in rhythmicity patterns. Both exogenous and endogenous sources of inter-individual variability in zebrafish circadian behaviour are detailed. Additionally, we focus on different environmental factors with the potential to entrain circadian processes in zebrafish. This review describes two principal ways whereby diurnal behavioural rhythms can be entrained: (i) modulation of organismal physiological state, which can have masking or enhancing effects on behavioural endpoints related to endogenous circadian rhythms, and (ii) modulation of period and amplitude of the endogenous circadian rhythm due to competitive relationships between the primary and secondary zeitgebers. In addition, different peripheral oscillators in zebrafish can be entrained by diverse zeitgebers. This complicated orchestra of divergent influences may cause variability in zebrafish circadian behaviours, which should be given attention when planning behavioural studies.

The Geomagnetic Field (GMF) Modulates Nutrient Status and Lipid Metabolism during Arabidopsis thaliana Plant Development

The Geomagnetic field (GMF) is a typical component of our planet. Plant perception of the GMF implies that any magnetic field (MF) variation would induce possible metabolic changes. In this work was we assessed the role of the GMF on Arabidopsis thaliana Col0 mineral nutrition and lipid metabolism during plant development. We reduced the local GMF (about 40 μT) to Near Null Magnetic Field (NNMF, about 30 nT) to evaluate the effects of GMF on Arabidopsis in a time-course (from rosette to seed-set) experiment by studying the lipid content (fatty acids, FA; and surface alkanes, SA) and mineral nutrients. The expression of selected genes involved in lipid metabolism was assessed by Real-Time PCR (qPCR). A progressive increase of SA with carbon numbers between 21 and 28 was found in plants exposed to NNMF from bolting to flowering developmental stages, whereas the content of some FA significantly (p < 0.05) increased in rosette, bolting and seed-set developmental stages. Variations in SA composition were correlated to the differential expression of several Arabidopsis 3-ketoacyl-CoAsynthase (KCS) genes, including KCS1, KCS5, KCS6, KCS8, and KCS12, a lipid transfer protein (LTPG1) and a lipase (LIP1). Ionomic analysis showed a significant variation in some micronutrients (Fe, Co, Mn and Ni) and macronutrients (Mg, K and Ca) during plant development of plants exposed to NNMF. The results of this work show that A. thaliana responds to variations of the GMF which are perceived as is typical of abiotic stress responses.

The Geomagnetic Field Is a Contributing Factor for an Efficient Iron Uptake in Arabidopsis thaliana

The Earth's magnetic field, defined as the geomagnetic field (GMF), is an unavoidable environmental factor for all living organisms. Variation in the GMF intensity was found to affect the content of some nutrients and their associated channels and transporters in Arabidopsis thaliana. In this work, we observed that reduction of the GMF to near null magnetic field (NNMF) affects the accumulation of metals in plant tissues, mainly iron (Fe) and zinc (Zn) content, while the content of others metals such as copper (Cu) and manganese (Mn) is not affected. Accordingly, Fe uptake genes were induced in the roots of NNMF-exposed plants and the root Fe reductase activity was affected by transferring GMF-exposed plant to NNMF condition. Under Fe deficiency, NNMF-exposed plants displayed a limitation in the activation of Fe-deficiency induced genes. Such an effect was associated with the strong accumulation of Zn and Cu observed under NNMF conditions. Overall, our results provide evidence on the important role of the GMF on the iron uptake efficiency of plants.

The Geomagnetic Field Is a Contributing Factor for an Efficient Iron Uptake in Arabidopsis thaliana

The Earth's magnetic field, defined as the geomagnetic field (GMF), is an unavoidable environmental factor for all living organisms. Variation in the GMF intensity was found to affect the content of some nutrients and their associated channels and transporters in Arabidopsis thaliana. In this work, we observed that reduction of the GMF to near null magnetic field (NNMF) affects the accumulation of metals in plant tissues, mainly iron (Fe) and zinc (Zn) content, while the content of others metals such as copper (Cu) and manganese (Mn) is not affected. Accordingly, Fe uptake genes were induced in the roots of NNMF-exposed plants and the root Fe reductase activity was affected by transferring GMF-exposed plant to NNMF condition. Under Fe deficiency, NNMF-exposed plants displayed a limitation in the activation of Fe-deficiency induced genes. Such an effect was associated with the strong accumulation of Zn and Cu observed under NNMF conditions. Overall, our results provide evidence on the important role of the GMF on the iron uptake efficiency of plants.

Wheat Space Odyssey: "From Seed to Seed". Kernel Morphology

The long-term autonomous existence of man in extraterrestrial conditions is associated with the need to cultivate plants-the only affordable and effective means for both providing oxygen and CO2 utilization, and providing one of the most habitual and energetically valuable products: plant food. In this study, we analyzed the results of the space odyssey of wheat and compared the morphological features of parental grains harvested from soil grown wheat plants, the grains obtained from plants grown in a specialized device for plant cultivation-the "Lada" space greenhouses during space flight in the ISS, and the grains obtained from plants in the same device on Earth. The seeds obtained under various conditions were studied using scanning electron microscopy. We studied the mutual location of the surface layers of the kernel cover tissues, the structural features of the tube and cross cells of the fruit coat (pericarp), and the birsh hairs of the kernels. It was found that the grains obtained under wheat plants cultivation on board of the ISS in near space had some specific differences from the parental, original grains, and the grains obtained from plants grown in the "Lada" greenhouse in ground conditions. These changes were manifested in a shortening of the birsh hairs, and a change in the size and relative arrangement of the cells of the kernel coat. We suggest that such changes are a manifestation of the sensitivity of the cytoskeleton reorganization systems and water exchange to the influence of particular physical conditions of space flight (microgravity, increased doses of radiation, etc.). Thus, the revealed changes did not hinder the wheat grains production "from seed to seed", which allows the cultivation of this crop in stable life support systems in near earth orbit.