ENHANCEMENT OF INVERTASE PRODUCTION BY Aspergillus niger OZ-3 USING LOW-INTENSITY STATIC MAGNETIC FIELDS

The aim of this study is to investigate the effect of low-intensity static magnetic fields (SMFs) on invertase activity and growth on different newly identified molds. The most positive effect of SMFs on invertase activity and growth was observed for Aspergillus niger OZ-3. The submerged production of invertase was performed with the spores obtained at the different exposure times (120, 144, 168, and 196 hr) and magnetic field intensities (0.45, 3, 5, 7, and 9 mT). The normal magnetic field of the laboratory was assayed as 0.45 mT (control). Optimization of magnetic field intensity and exposure time significantly increased biomass production and invertase activity compared to 0.45 mT. The maximum invertase activity (51.14 U/mL) and biomass concentration (4.36 g/L) were achieved with the spores obtained at the 144 hr exposure time and 5 mT magnetic field intensity. The effect of low-intensity static magnetic fields (SMFs) on invertase activities of molds was investigated for the first time in the present study. As an additional contribution, a new hyper-invertase-producing mold strain was isolated.

Supplemental materials are available for this article. Go to the publisher's online edition of Preparative Biochemistry and Biotechnology to view the supplemental file.     

Overexpression of miR-26b-5p regulates the cell cycle by targeting CCND2 in GC-2 cells under exposure to extremely low frequency electromagnetic fields

The increasing prevalence of extremely low frequency electromagnetic fields (ELF-EMFs) exposure has raised considerable public concern regarding the potential hazardous effects of ELF-EMFs on male reproductive function. Increasing evidence indicates that miRNAs are necessary for spermatogenesis and male fertility. However, the regulation of miRNA expression and the roles of miRNAs in response to ELF-EMFs remain unclear. In our study, mouse spermatocyte-derived GC-2 cells were intermittently exposed to a 50 Hz ELF-EMF for 72 h (5 min on/10 min off) at magnetic field intensities of 1 mT, 2 mT and 3 mT. MiR-26b-5p was differentially expressed in response to different magnetic field intensities of ELF-EMFs. The host gene CTDSP1 showed an unmethylation status in GC-2 cells at different magnetic field intensities of ELF-EMF exposure. MiR-26b-5p had no significant, obvious influence on the cell viability, apoptosis or cell cycle of GC-2 cells. However, the overexpression of miR-26b-5p significantly decreased the percentage of G0/G1 phase cells and slightly increased the percentage of S phase cells compared to the sham group that was exposed to a 50 Hz ELF-EMF. Computational algorithms identified Cyclin D2 (CCND2) as a direct target of miR-26b-5p. MiR-26b-5p and a 50 Hz ELF-EMF altered the expression of CCND2 at both the mRNA and protein levels. Overexpressed miR-26b-5p in GC-2 cells can change the mRNA expression of CCND2 following 50 Hz ELF-EMF at 3 mT. These findings demonstrate that miR-26b-5p could serve as a potential biomarker following 50 Hz ELF-EMF exposure, and miR-26b-5p-CCND2-mediated cell cycle regulation might play a pivotal role in the biological effects of ELF-EMFs.     

极低频磁场对人肝癌细胞生长、代谢及细胞周期的影响

目的研究一定参数的极低频磁场对人肝癌细胞(SK-HEP-1)在诸多方面的影响。方法在整个SK-HEP-1细胞的培养周期中用50Hz,20mT的极低频磁场对其进行作用,并检测作用后细胞的增殖活性、生长动力学、代谢以及细胞周期的变化。结果50Hz,20mT的极低频磁场对SK-HEP-1细胞的生长与代谢有抑制作用,并能阻碍其有丝分裂的进行。结论50Hz,20mT的极低频磁场为治疗人类恶性肿瘤提供了一种可能的手段。     

Enhancement of the hydrolysis activity of F0F1‐ATPases using 60 Hz magnetic fields

The effects of extremely low frequency (ELF) magnetic fields on membrane F₀F₁‐ATPase activity have been studied. When the F₀F₁‐ATPase was exposed to 60 Hz magnetic fields of different magnetic intensities, 0.3 and 0.5 mT magnetic fields enhanced the hydrolysis activity, whereas 0.1 mT exposure caused no significant changes. Even if the F₀F₁‐ATPase was inhibited by N,N‐dicyclohexylcarbodiimide, its hydrolysis activity was enhanced by a 0.5 mT 60 Hz magnetic field. Moreover, when the chromatophores which were labeled with F‐DHPE were exposed to a 0.5 mT, 60 Hz magnetic field, it was found that the pH of the outer membrane of the chromatophore was unchanged, which suggested that the magnetic fields used in this work did not affect the activity of F0. Taken together, our results show that the effects of magnetic fields on the hydrolysis activity of the membrane F₀F₁‐ATPases were dependent on magnetic intensity and the threshold intensity is between 0.1 and 0.3 mT, and suggested that the F1 part of F₀F₁‐ATPase may be an end‐point affected by magnetic fields. Bioelectromagnetics 30:663–668, 2009. © 2009 Wiley‐Liss, Inc.     

Age-Dependent Effects of ELF-MF on Oxidative Stress in the Brain of Mongolian Gerbils

The aim of study was to investigate the effects of extremely low frequency magnetic field (ELF-MF; 50 Hz; 0.1, 0.25 and 0.5 mT) on oxidative stress in the brain of 3- (adult) and 10-month-old (middle-aged) gerbils. Nitric oxide (NO) level, superoxide (O₂ ^?) production, superoxide dismutase (SOD) activity, and index of lipid peroxidation (ILP) were measured in the forebrain cortex, striatum, hippocampus, and cerebellum immediately and 3 days after cessation of 7-day exposure. In all gerbils, ELF-MF significantly increased oxidative stress in all tested brain regions. This effect was correlated with the value of magnetic induction and was higher in middle-aged gerbils. Three days after cessation of exposure, the values of examined parameters were closer to control levels. In adult gerbils, the effect of ELF-MF of 0.1 mT on NO level, O₂ ^? production and SOD activity was almost fully disappeared, and ILP was at the control level regardless of the value of magnetic induction. In middle-aged gerbils, the effect of ELF-MF was still present but to a lesser degree than those observed immediately after cessation of exposure. These findings pointed out the ability of ELF-MF to induce age- and magnetic induction-dependent modification of oxidative stress in the brain.     

Effect of sinusoidally varying magnetic fields on cell proliferation and adenosine deaminase specific activity

The effect of sinusoidally varying magnetic fields (SVMF) on chick embryo fibroblasts (CEF) was examined by two independent methods: 1) measurement of cell proliferation at 0.06–0.7 mT (100, 60 and 50 Hz) using a colorimetric assay (MTT); 2) monitoring of specific activity of adenosine deaminase (ADA) at 0.3 and 0.7 mT, 60 Hz. Both increased cell proliferation and reduced ADA specific activity are associated with cell transformation. The MTT test showed an increase in cell proliferation of up to 64% after a 24 h exposure to SVMF at 100 Hz, 0.7 mT. Cell proliferation at constant frequency (100 Hz) depended on SVMF intensity. Cell proliferation at constant intensity (0.7 mT) increased with increasing field frequency. At 0.7 mT, 60 Hz cell proliferation increased by 31%, 28%, and 26% when measured by hemocytometry, ³H-thymidine incorporation, and the MTT assay, respectively. ADA specific activity in CEF decreased by circa 48% on exposure to SVMF at 60 Hz, 0.3 mT for 24 h; only a statistically insignificant trend was seen at 0.7 mT, 60 Hz. Our findings showed that CEF cell proliferation and ADA specific activity were modified by SVMF. Both methods, independently, qualitatively detect a magnetic field effect. Bioelectromagnetics 19:46–52, 1998. © 1998 Wiley-Liss, Inc.     

Influence of extremely low frequency magnetic fields on chromosomes and the mitotic cycle in Vicia faba L., the broad bean

Vicia faba seedlings were subjected to one of the following magnetic fields continuously for 3 days: 0 Hz (DC) at 5 mT, 50 Hz at 1.5 mT, 60 Hz at 1.5 mT, and 75 Hz at 1.5 mT. The lengths of all the phases of mitosis differed from the controls in all treatments using alternating magnetic fields and for prophase and metaphase in the DC condition. In particular, all treatments increased the length of prophase significantly in meristematic root-tip cells compared with the controls. The implications of these results for chromosome coiling are discussed. The length of prophase, however, did not vary significantly between any of the treatments. Furthermore, none of the exposed seedlings had a greater frequency of chromosome breakages above that of the control plants. Bioelectromagnetics 19:152–161, 1998. © 1998 Wiley-Liss, Inc.     

Influence of weak static and 50 Hz magnetic fields on the redox activity of cytochrome-C oxidase

The effects of static and 50 Hz magnetic fields on cytochrome-C oxidase activity were investigated in vitro by strictly controlled, simultaneous polarographic measurements of the enzyme's high- and low-affinity redox reaction. Cytochrome-C oxidase was isolated from beef heart. Control experiments were carried out in the ambient geomagnetic and 50 Hz magnetic fields at respective flux densities of 45 and 1.8 μT. The experimentally applied fields, static and time-varying, were generated by Helmholtz coils at flux densities between 50 μT and 100 mT. Exposures were timed to act either on the combined enzyme-substrate interchange or directly on the enzyme's electron and proton translo-cations. Significant changes as high as 90% of the overall cytochrome-C oxidase activity resulted during exposure (1) to a static magnetic field at 300 μT or 10 mT in the high-affinity range, and (2) to a 50 Hz magnetic field at 10 or 50 mT in the low-affinity range. No changes were observed at other flux densities. After exposure to a change-inducing, static or time-varying field, normal activity returned. © 1993 Wiley-Liss. Inc.     

Influence of Magnetic Field on Brain Activity During Administration of Caffeine

The aim of the present work is to evaluate the effect of caffeine, the world’s most popular psychoactive drug, on the electric activity of the rat’s brain that exposed to extremely low-frequency magnetic field (ELF-MF), during 15 days. The obtained results showed that administration of caffeine in a group of rats by dose of 10 mg/kg (equivalent to human daily consumption) caused a reduction in the mean power amplitude of electroencephalogram (EEG) trace for almost all frequency bands especially α (8–12 Hz). It was observed that the influence of caffeine was more evident in motor cortex than in visual cortex. While the exposure of another group to ELF-MF of intensity 0.2 mT during the same period caused an enhancement in the mean power amplitude of most EEG frequency bands; this was more observed in the right hemisphere of the brain than that of the left hemisphere. The administration of caffeine while rats were exposed to ELF-MF, led, after 5 days of exposure, to a great increase in the mean power amplitude of α band at all places of recording electrodes. It may be concluded that caffeine administration was more effective in reducing the hazardous of ELF-MF in motor cortex than in visual cortex.     

Ameliorative Effects of a Static Magnetic Field on Hyssop (Hyssopus officinalis L.) Growth and Phytochemical Traits Under Water Stress

The present study was carried out in order to evaluate the promoting effect of a static magnetic field (SMF) on drought tolerance and medicinal properties in Hyssopus officinalis. In the current work, the effect of seed priming with SMF (45, 90, 200, and 250 mT for 5 min) was investigated in 60-day-old hyssop (H. officinalis) plants that were irrigated every 8 days. The assessments consisted of total dry mass, membrane integrity, photosynthetic pigment concentrations, polyphenol content, antioxidant enzyme activities, and antioxidant capacity. Compared with exclusively water stress, magnetopriming, particularly at 200 mT, significantly altered these parameters in the grown plants. At this intensity, the level of total dry mass, total chlorophyll, and polyphenol content increased by 94%, 2.5- and 7.7-fold, respectively. Also, the level of electrolyte leakage and malondialdehyde decreased by 35% and 33%. The reducing power, DPPH (1,1-diphenyl-2-picrylhydrozyl), and superoxide anion-scavenging activities were highly augmented as well. Magnetopriming at 200 mT increased catalase (+92%) and ascorbate peroxidase (+2.3-fold) activities. However, the highest activity of guaiacol peroxidase was recorded at 90 mT. Generally, the present study illustrated the positive effect of magnetopriming (200 mT) on improvement of drought tolerance in H. officinalis through protection of cellular membrane integrity, maintenance of photosynthetic pigment content, and alternation of antioxidant enzyme activities. Furthermore, the data showed this treatment (200 mT) not only had no negative effect on medicinal properties of H. officinalis, but also improved it via increasing total phenolic content and antioxidant capacity. Bioelectromagnetics. 2020;41:403–412. © 2020 Bioelectromagnetics Society.     

Sinusoidal 60 Hz electromagnetic fields failed to induce changes in protein synthesis in Escherichia coli

Escherichia coli JM83 {F^? ara Δ(lac-proAB) rpsL [?80dΔ(lacZ)M15]} in midlog growth phase at 30 °C were exposed to 60 Hz sinusoidal magnetic field of 3 mT of nonuniform diverging flux, inducing a nonuniform electric field with a maximum intensity of 32 μV/cm using an inductor coil. Exposed and unexposed control cells were maintained at 30.8 ± 0.1 °C and 30.5 ± 0.1 °C, respectively. Quadruplicate samples of exposed and unexposed E. coli cells were simultaneously radiolabeled with ³⁵S-L-methionine at 10 min intervals over 2 hr. Radiochemical incorporation into proteins was analyzed via liquid scintillation counting and by denaturing 12.5% polyacrylamide gel electrophoresis. The results showed that E. coli exposed to a 60 Hz magnetic field of 3 mT exhibited no qualitative or quantitative changes in protein synthesis compared to unexposed cells. Thus small prokaryotic cells (less than 2 μm × 0.5 μm) under constant-temperature conditions do not alter their protein synthesis following exposure to 60 Hz magnetic fields at levels at 3 mT. © 1994 Wiley-Liss, Inc.     

Absence of DNA damage after 60-Hz electromagnetic field exposure combined with ionizing radiation,hydrogen peroxide,or c-Myc overexpression

The principal objective of this study was to assess the DNA damage in a normal cell line system after exposure to 60 Hz of extremely low frequency magnetic field (ELF-MF) and particularly in combination with various external factors, via comet assays. NIH3T3 mouse fibroblast cells, WI-38 human lung fibroblast cells, L132 human lung epithelial cells, and MCF10A human mammary gland epithelial cells were exposed for 4 or 16 h to a 60-Hz, 1 mT uniform magnetic field in the presence or absence of ionizing radiation (IR, 1 Gy), H₂O₂ (50 μM), or c-Myc oncogenic activation. The results obtained showed no significant differences between the cells exposed to ELF-MF alone and the unexposed cells. Moreover, no synergistic or additive effects were observed after 4 or 16 h of pre-exposure to 1 mT ELF-MF or simultaneous exposure to ELF-MF combined with IR, H₂O₂, or c-Myc activation.     

No effect of exposure to static and sinusoidal magnetic fields on nitric oxide production by macrophages

The effects of exposure to static (1–100 mT) or sinusoidal (1 Hz, 1.6 mT) magnetic fields on the production of nitric oxide (NO) by murine BCG-activated macrophages were investigated. In these cells, the inducible isoform of NO synthase is present. No significant differences were observed in nitrite levels among exposed, sham-exposed, or control macrophages after exposure for 14 h to static fields of 1, 10, 50, and 100 mT and to sinusoidal 1.6 mT, 1 Hz magnetic fields. © 1996 Wiley-Liss, Inc.     

In vitro effects of 50 Hz magnetic fields on oxidatively damaged rabbit red blood cells

The aim of this study was to investigate the effects of 50 Hz magnetic fields (0.2–0.5 mT) on rabbit red blood cells (RBCs) that were exposed simultaneously to the action of an oxygen radical-generating system, Fe(II)/ascorbate. Previous data obtained in our laboratory showed that the exposure of rabbit erythrocytes or reticulocytes to Fe(II)/ascorbate induces hexokinase inactivation, whereas the other glycolytic enzymes do not show any decay. We also observed depletion of reduced glutathione (GSH) content with a concomitant intracellular and extracellular increase in oxidized glutathione (GSSG) and a decrease in energy charge. In this work we investigated whether 50 Hz magnetic fields could influence the intracellular impairments that occur when erythrocytes or reticulocytes are exposed to this oxidant system, namely, inactivation of hexokinase activity, GSH depletion, a change in energy charge, and hemoglobin oxidation. The results obtained indicate that a 0.5 mT magnetic field had no effect on intact RBCs, whereas it increased the damage in an oxidatively stressed erythrocyte system. In fact, exposure of intact erythrocytes incubated with Fe(II)/ascorbate to a 0.5 mT magnetic field induced a significant further decay in hexokinase activity (about 20%) as well as a twofold increase in methemoglobin production compared with RBCs that were exposed to the oxidant system alone. Although further studies will be needed to determine the physiological implications of these data, the results reported in this study demonstrate that the effects of the magnetic fields investigated are able to potentiate the cellular damage induced in vitro by oxidizing agents. Bioelectromagnetics 18:125–131, 1997. © 1997 Wiley-Liss, Inc.     

Enhanced mutagenic effect of a 60 Hz time-varying magnetic field on numbers of azide-induced TA100 revertant colonies

Forty-eight hours exposure to a two Gauss (0.2 mT) rms 60 Hz time varying sinusoidal electromagnetic field increased the number of azide induced TA100 revertant colonies of Salmonella typhimurium 14% as compared with controls in the ambient < 2 milli-Gauss 60 Hz field. In the absence of the electromagnetic field, the numbers of mutant colonies grown within and outside the non-energized coil were nearly identical. Without azide, the number of “spontaneous” mutant colonies forming in the experimental field was not statistically significant from numbers of colonies not exposed to field effects. Experimental temperature variation of 2 °C had little effect on colony formation, and the enhanced production of revertant colonies in the presence of the magnetic field was maintained during continued culture for 5 additional days. © 1994 Wiley-Liss, Inc.     

Do ELF magnetic fields affect human reaction time?

Two double-blind studies were run in an attempt to confirm the finding that a 0.2 Hz magnetic field affects simple reaction time (RT) in humans, whereas a 0.1 Hz field does not. In the first experiment, 12 volunteer subjects were exposed to a continuous 0.2 Hz, 0.1 Hz, or sham field in a fully counter-balanced, within-subjects design. Subjects were run singly for one condition each day over 3 consecutive days with a field strength of 1.1 mT and a daily exposure duration of 5 min. Neither magnetic field had any effect on RT at any time during the exposure. One condition of a second study, using a new group of 24 volunteer subjects, also failed to find any field effects at 0.2 Hz. Additionally, the second study failed to show any effects when the frequency, flux density, and field orientation were set according to parametric resonance theory. It is suggested that, although ELF magnetic field effects on human behaviour may be elusive, future research can improve detection rates by paying greater attention to reducing error variance and increasing statistical power. © 1995 Wiley-Liss, Inc.     

Oviposition and development of Drosophila modified by magnetic fields

Drosophila flies placed in a habitat with two lateral boxes demonstrated sensitivity to magnetic fields: Oviposition decreased by exposure to pulsated extremely low frequency (ELF) (100)Hz, 1.76 miliTesla (mT) and sinusosidal fields (50 Hz, 1 mT), while there was no initial effect of exposure to a static magnetic field (4.5 mT). Drosophila eggs treated for 48 h with the above described fields showed that (1) mortality of eggs was lower in controls than in eggs exposed to all tested magnetic fields; (2) mortality of larvae increased when a permanent magnet was used; (3) mortality of pupae was highest when a permanent magnet was used; and (4) general adult viability was highest in controls (67%) and diminished progressively when eggs were exposed to pulsated (55%), sinusoidal (45%), and static (35%) magnetic fields.     

Effects of 50‐Hz magnetic field exposure on hormone secretion and apoptosis‐related gene expression in human first trimester villous trophoblasts in vitro

Evidence from epidemiological and animal studies showed that exposure to extremely low frequency magnetic fields (ELF‐MF) could produce deleterious effects on reproduction. In order to investigate the possible mechanism of MF exposure on reproductive effects, first trimester human chorionic villi at 8–10 weeks' gestation were obtained, and trophoblasts were isolated, cultured, and exposed to a 50‐Hz MF for different durations. The human chorionic gonadotropin (hCG) and progesterone in the culture medium was measured by electrochemiluminescence immunoassay. The mRNA levels of apoptosis‐related genes bcl‐2, bax, caspase‐3, p53, and fas in trophoblasts were analyzed using real‐time RT‐PCR. The results showed that exposure of trophoblasts to MF at 0.2 mT for 72 h did not affect secretion of hCG and progesterone from these cells. There was also no significant change in secretion of these hormones when trophoblasts were exposed to a 0.4 mT MF for 48 h. However, MF significantly inhibited hCG and progesterone secretion of trophoblasts after exposure for 72 h at 0.4 mT. Results of apoptosis‐related gene expression analysis showed that, within 72 h of exposure at 0.4 mT, there was no significant difference between MF exposure and control on the expression pattern of each gene. Based on results of the present experiment, it is suggested that exposure to MF for a longer duration (72 h) could inhibit secretion of hCG and progesterone by human first trimester villous trophoblasts, however, the effect might not be related to trophoblast apoptosis. Bioelectromagnetics 31:566–572, 2010. © 2010 Wiley‐Liss, Inc.     

Acute exposure to a 60 Hz magnetic field increases DNA strand breaks in rat brain cells

Acute (2 h) exposure of rats to a 60 Hz magnetic field (flux densities 0.1, 0.25, and 0.5 mT) caused a dose-dependent increase in DNA strand breaks in brain cells of the animals (assayed by a microgel electrophoresis method at 4 h postexposure). An increase in single-strand DNA breaks was observed after exposure to magnetic fields of 0.1, 0.25, and 0.5 mT, whereas an increase in double-strand DNA breaks was observed at 0.25 and 0.5 mT. Because DNA strand breaks may affect cellular functions, lead to carcinogenesis and cell death, and be related to onset of neurodegenerative diseases, our data may have important implications for the possible health effects of exposure to 60 Hz magnetic fields. Bioelectromagnetics 18:156–165, 1997. © 1997 Wiley-Liss, Inc.     

The Effect of ELF Magnetic Field on Tumor Growth after Electrochemotherapy

From a fundamental point of view, chemotherapy is the most widely used treatment for cancers despite its side effects on normal cells and tissues. Electrochemotherapy (ECT) is a method for increasing the permeability of cancer cells to drugs and, hence, decreasing their dosage. It apparently creates electropores on the cell membrane using electric pulses. ECT can decrease tumor volume; but this effect is not permanent, and partial regrowth has been reported. The aim of this study was to investigate the potential of magnetic fields in preventing the regrowth of tumors after ECT. Tumoral Balb/c mice were exposed to a magnetic field (15 mT, 50 Hz) for 12 days after treating additionally with 70 V/cm electric pulses and bleomycin at the first day. The magnetic field caused a significant reduction in tumor volumes, while there was no significant difference between the ECT and the electroporation with ECT and magnetic field groups. The exploited magnetic field (15 mT, 50 Hz) could decrease the tumor growth rate significantly, without any effect on ECT efficiency.