Effect of 2.45 mT sinusoidal 50 Hz magnetic field on Saccharomyces cerevisiae strains deficient in DNA strand breaks repair

Critical role of model organism selection in assessing weak urban electromagnetic field effects: Implications for human health

The impact of electromagnetic fields on human health has been investigated in recent years using various model organisms, yet the findings remain unclear. In our work, we examined the effect of less-explored, weak electromagnetic fields commonly found in the urban environments we inhabit. We studied different impacts of electromagnetic fields with a frequency of 50 Hz and a combination of 50 Hz and 150 Hz, on both yeasts (Saccharomyces cerevisiae) and human macrophages. We determined growth, survival, and protein composition (SDS-PAGE) (Saccharomyces cerevisiae) and morphology of macrophages (human monocytic cell line). In yeast, the sole observed change after 24 h of exposure was the extension of the exponential growth phase by 17 h. Conversely, macrophages exhibited morphological transformations from the anti-inflammatory to the pro-inflammatory type within just 2 h of exposure to the electromagnetic field. Our results suggest that effects of electromagnetic field largely depend on the model organism. The selection of an appropriate model organism proves essential for the study of the specific impacts of electromagnetic fields. The potential risk associated with the presence of pro-inflammatory M1 macrophages in everyday urban environments primarily arises from the continual promotion of inflammatory reactions within a healthy organism and deserves further investigation.

Exploring the impact of magnetic fields on biomass production efficiency under aerobic and anaerobic batch fermentation of Saccharomyces cerevisiae

In this work, the effect of moderate electromagnetic fields (2.5, 10, and 15 mT) was studied using an immersed coil inserted directly into a bioreactor on batch cultivation of yeast under both aerobic and anaerobic conditions. Throughout the cultivation, parameters, including CO2 levels, O2 saturation, nitrogen consumption, glucose uptake, ethanol production, and yeast growth (using OD 600 measurements at 1-h intervals), were analysed. The results showed that 10 and 15 mT magnetic fields not only statistically significantly boosted and sped up biomass production (by 38-70%), but also accelerated overall metabolism, accelerating glucose, oxygen, and nitrogen consumption, by 1-2 h. The carbon balance analysis revealed an acceleration in ethanol and glycerol production, albeit with final concentrations by 22-28% lower, with a more pronounced effect in aerobic cultivation. These findings suggest that magnetic fields shift the metabolic balance toward biomass formation rather than ethanol production, showcasing their potential to modulate yeast metabolism. Considering coil heating, opting for the 10 mT magnetic field is preferable due to its lower heat generation. In these terms, we propose that magnetic field can be used as novel tool to increase biomass yield and accelerate yeast metabolism.

Molecular Mechanisms of Resistance to Ionizing Radiation in S. cerevisiae and Its Relationship with Aging, Oxidative Stress, and Antioxidant Activity

The repair of the damage produced to the genome and proteome by the action of ionizing radiation, oxidizing agents, and during aging is important to maintain cellular homeostasis. Many of the metabolic pathways influence multiple processes. In this way, this work aims to study the relationship between resistance/response to ionizing radiation, cellular aging, and the response mechanisms to oxidative stress, free radicals, reactive oxygen species (ROS), and antioxidant activity in the yeast S. cerevisiae. Systems biology allows us to use tools that reveal the molecular mechanisms common to different cellular response phenomena. The results found indicate that homologous recombination, non-homologous end joining, and base excision repair pathways are the most important common processes necessary to maintain cellular homeostasis. The metabolic routes of longevity regulation are those that jointly contribute to the three phenomena studied. This study proposes eleven common biomarkers for response/resistance to ionizing radiation and aging (EXO1, MEC1, MRE11, RAD27, RAD50, RAD51, RAD52, RAD55, RAD9, SGS1, YKU70) and two biomarkers for response/resistance to radiation and oxidative stress, free radicals, ROS, and antioxidant activity (NTG1, OGG1). In addition, it is important to highlight that the HSP104 protein could be a good biomarker common to the three phenomena studied.

Hypomagnetic Fields and Their Multilevel Effects on Living Organisms

The Earth’s magnetic field is one of the basic abiotic factors in all environments, and organisms had to adapt to it during evolution. On some occasions, organisms can be confronted with a significant reduction in a magnetic field, termed a “hypomagnetic field—HMF”, for example, in buildings with steel reinforcement or during interplanetary flight. However, the effects of HMFs on living organisms are still largely unclear. Experimental studies have mostly focused on the human and rodent models. Due to the small number of publications, the effects of HMFs are mostly random, although we detected some similarities. Likely, HMFs can modify cell signalling by affecting the contents of ions (e.g., calcium) or the ROS level, which participate in cell signal transduction. Additionally, HMFs have different effects on the growth or functions of organ systems in different organisms, but negative effects on embryonal development have been shown. Embryonal development is strictly regulated to avoid developmental abnormalities, which have often been observed when exposed to a HMF. Only a few studies have addressed the effects of HMFs on the survival of microorganisms. Studying the magnetoreception of microorganisms could be useful to understand the physical aspects of the magnetoreception of the HMF.

Inactivation of RAD52 and HDF1 DNA repair genes leads to premature chronological aging and cellular instability

The present study aims to investigate the role of radiation sensitive 52 (RAD52) and high-affinity DNA binding factor 1 (HDF1) DNA repair genes on the life span of budding yeasts during chronological aging. Wild type (wt) and rad52, hdf1, and rad52 hdf1 mutant Saccharomyces cerevisiae strains were used. Chronological aging and survival assays were studied by clonogenic assay and drop test. DNA damage was analyzed by electrophoresis after phenol extraction. Mutant analysis, colony forming units and the index of respiratory competence were studied by growing on dextrose and glycerol plates as a carbon source. Rad52 and rad52 hdf1 mutants showed a gradual decrease in surviving fraction in relation to wt and hdf1 mutant during aging. Genomic DNA was spontaneously more degraded during aging, mainly in rad52 mutants. This strain showed an increased percentage of revertant colonies. Moreover, all mutants showed a decrease in the index of respiratory competence during aging. The inactivation of RAD52 leads to premature chronological aging with an increase in DNA degradation and mutation frequency. In addition, RAD52 and HDF1 contribute to maintain the metabolic state, in a different way, during chronological aging. The results obtained could have important implications in the chronobiology of aging.

Inhibition of Salmonella typhi growth using extremely low frequency electromagnetic (ELF-EM) waves at resonance frequency

AIMS

Typhoid is a serious disease difficult to be treated with conventional drugs. The aim of this study was to demonstrate a new method for the control of Salmonella typhi growth, through the interference with the bioelectric signals generated from the microbe during cell division by extremely low frequency electromagnetic waves (ELF-EMW-ELF-EM) at resonance frequency.

METHODS AND RESULTS

Isolated Salmonella typhi was subjected to square amplitude modulated waves (QAMW) with different modulation frequencies from two generators with constant carrier frequency of 10 MHz, amplitude of 10 Vpp, modulating depth ± 2 Vpp and constant field strength of 200 V m(-1) at 37°C. Both the control and exposed samples were incubated at the same conditions during the experiment. The results showed that there was highly significant inhibition effect for Salm. typhi exposed to 0·8 Hz QAMW for a single exposure for 75 min. Dielectric relaxation, TEM and DNA results indicated highly significant changes in the molecular structure of the DNA and cellular membrane resulting from the exposure to the inhibiting EM waves.

CONCLUSIONS

It was concluded that finding out the inhibiting resonance frequency of ELF-EM waves that deteriorates Salm. typhi growth will be promising method for the treatment of Salm. typhi infection either in vivo or in vitro.

SIGNIFICANCE AND IMPACT OF THE STUDY

This new non-invasive technique for treatment of bacterial infections is of considerable interest for the use in medical and biotechnological applications.

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), H(2)O(2) (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, H(2)O(2), or c-Myc activation.

Increased γ-H2AX by exposure to a 60-Hz magnetic fields combined with ionizing radiation, but not hydrogen peroxide, in non-tumorigenic human cell lines

PURPOSE

Genotoxic effects have been considered the gold standard to determine if an environmental factor is a carcinogen, but the currently available data for extremely low frequency time-varying magnetic fields (ELF-MF) remain controversial. As an environmental stimulus, the effect of ELF-MF on cellular DNA may be subtle. Therefore, a more sensitive method and systematic research strategy are warranted to evaluate genotoxicity.

MATERIALS AND METHODS

We investigated the effect of ELF-MF in combination with ionizing radiation (IR) or H(2)O(2) on the DNA damage response of expression of phosphorylated H2AX (γ-H2AX) and production of γ-H2AX foci in non-tumorigenic human cell systems consisting of human lung fibroblast WI-38 cells and human lung epithelial L132 cells.

RESULTS

Exposure to a 60-Hz, 2 mT ELF-MF for 6 h produced increased γ-H2AX expression, as well as γ-H2AX foci production, a common DNA double-strand break (DSB) marker. However, exposure to a 1 mT ELF-MF did not have the same effect. Moreover, 2 mT ELF-MF exposure potentiated the expression of γ-H2AX and γ-H2AX foci production when combined with IR, but not when combined with H(2)O(2).

CONCLUSIONS

ELF-MF could affect the DNA damage response and, in combination with different stimuli, provide different effects on γ-H2AX.

Could radiotherapy effectiveness be enhanced by electromagnetic field treatment?

One of the main goals in radiobiology research is to enhance radiotherapy effectiveness without provoking any increase in toxicity. In this context, it has been proposed that electromagnetic fields (EMFs), known to be modulators of proliferation rate, enhancers of apoptosis and inductors of genotoxicity, might control tumor recruitment and, thus, provide therapeutic benefits. Scientific evidence shows that the effects of ionizing radiation on cellular compartments and functions are strengthened by EMF. Although little is known about the potential role of EMFs in radiotherapy (RT), the radiosensitizing effect of EMFs described in the literature could support their use to improve radiation effectiveness. Thus, we hypothesized that EMF exposure might enhance the ionizing radiation effect on tumor cells, improving the effects of RT. The aim of this paper is to review reports of the effects of EMFs in biological systems and their potential therapeutic benefits in radiotherapy.

Effect of extremely low frequency magnetic field exposure on DNA transposition in relation to frequency, wave shape and exposure time

PURPOSE

To examine the effect of extremely low frequency magnetic field (ELF-MF) exposure on transposon (Tn) mobility in relation to the exposure time, the frequency and the wave shape of the field applied.

MATERIALS AND METHODS

Two Escherichia coli model systems were used: (1) Cells unable to express β-galactosidase (LacZ(-)), containing a mini-transposon Tn10 element able to give ability to express β-galactosidase (LacZ(+)) upon its transposition; therefore in these cells transposition activity can be evaluated by analysing LacZ(+) clones; (2) cells carrying Fertility plasmid (F(+)), and a Tn5 element located on the chromosome; therefore in these cells transposition activity can be estimated by a bacterial conjugation assay. Cells were exposed to sinusoidal (SiMF) or pulsed-square wave (PMF) magnetic fields of various frequencies (20, 50, 75 Hz) and for different exposure times (15 and 90 min).

RESULTS

Both mini-Tn10 and Tn5 transposition decreased under SiMF and increased under PMF, as compared to sham exposure control. No significant difference was found between frequencies and between exposure times.

CONCLUSIONS

ELF-MF exposure affects transposition activity and the effects critically depend on the wave shape of the field, but not on the frequency and the exposure time, at least in the range observed.