FTIR and UV spectroscopy in real-time monitoring of S. cerevisiae cell culture

A combination of FTIR and UV spectroscopy is proposed as a novel technique for integrated real-time monitoring of metabolic activity and growth rates of cell cultures, required for systematic studies of cellular low-frequency (LF) electric and magnetic field (EMF) effects. As an example, we investigated simultaneous influence of periodic LF 3D EMFs on a culture of Saccharomyces cerevisiae (baker's yeast) cells. Amplitudes, frequencies and phases of the field components were the variable parameters. Electromagnetic fields were found to efficiently control the activity of the yeast cells, with the resulting CO(2) production rates, as monitored by FTIR spectroscopy, varying by at least one order of magnitude due to the field action. Additionally, population dynamics of the yeast cells was monitored by UV absorption of the yeast culture at λ(prob)?=?320?nm, and compared to the CO(2) production rates. The detected physiologically active frequencies are all below 1?kHz, namely, 800?Hz excitation was effective in reducing the metabolic rates and arresting cell proliferation, whereas 200?Hz excitation was active in accelerating both cell proliferation and overall metabolic rates. The proposed methods produce objective, reliable and quantitative real-time results within minutes and may be used in various tasks that could benefit from a rapid feedback they provide in the form of metabolic and growth rates. Amplitude and frequency dependences of the LF EMF effects from individual field components with different polarizations were recorded and qualitatively interpreted based on a simple model, describing ion diffusion through a membrane channel.     

Effect of 50 Hz sinusoidal electromagnetic field on the kinetics of 14CO2 exhalation after [14C]‐N‐Nitrosodiethylamine administration in mice

N‐Nitrosodiethylamine (NDEA) has been identified as a typical environmental carcinogen. Its metabolism was studied in mice under the influence of an electromagnetic field (EMF). After intraperitoneal administration of [¹⁴C]‐NDEA, 0.2 μCi/100 g body weight resulted in 22.8% of the total radioactivity exhaled as ¹⁴CO₂ within 1 h. Mice were exposed to a 50 Hz, 2 mT (rms) electromagnetic field, 8 h/day for 8 weeks. There was a significant increase in the metabolic turnover of [¹⁴C]‐NDEA into ¹⁴CO₂ at the end of both 6 and 8 weeks of field exposure, i.e., 26.9% and 37.4% respectively. The enhanced capacity of mice to metabolize NDEA after the exposure to EMF may result in animals with a smaller amount of the bioactive carcinogen burden, thereby indicating a protective role of 2 mT EMF in a whole animal study. Bioelectromagnetics 20:1–4, 1999. © 1999 Wiley‐Liss, Inc.     

Expression of genes involved in symbiotic carbon and nitrogen transport in Pinus taeda mycorrhizal roots exposed to CO2 enrichment and nitrogen fertilization

As atmospheric carbon dioxide (CO₂) concentrations rise, one important mechanism by which plants can gain greater access to necessary soil nutrients is through greater investment in their mycorrhizal symbionts. In this study, we tested the hypotheses that (1) plants increase C allocation to ectomycorrhizal fungi (EMF) under elevated CO₂ conditions, (2) N fertilization decreases C allocation to EMF, and (3) EMF activity at the site of symbiotic C and nutrient exchange is enhanced with CO₂ enrichment. To test these hypotheses, we examined expression levels of Pinus taeda genes encoding monosaccharide transport (MST) and ammonium transport (AMT) proteins thought to be involved in symbiotic C and N movement, respectively, from mycorrhizal root tips exposed to CO₂ and N fertilization. We also examined EMF ribosomal RNA expression (18S rRNA) to determine EMF activity. There was a trend toward lower relative MST expression with increased CO₂. AMT expression levels showed no significant differences between control and treatment plots. EMF 18S rRNA expression was increased in CO₂-enriched plots and there was a marginally significant positive interactive effect of CO₂ and N fertilization on expression (p = 0.09 and 0.10, respectively). These results are consistent with greater C allocation to EMF and greater EMF metabolic activity under elevated CO₂ conditions, although selective allocation of C to particular EMF species and greater fungal biomass on roots are plausible alternative hypotheses.     

The impact of background radiation,illumination and temperature on EMF-induced changes of aqua medium properties

The effects of extremely low frequency electromagnetic field (ELF EMF) on physicochemical properties of physiological solution at different environmental media were studied. The existence of frequency “windows” at 4 and 8 Hz frequencies of ELF EMF having effects on heat fusion period, hydrogen peroxide (H₂O₂) formation and oxygen (O₂) content of water solution and different dependency on temperature, background radiation and illumination was shown. Obtained data allow us to suggest that EMF-induced effect on water physicochemical properties depends on abovementioned environmental factors. As cell bathing medium is a target for biological effects of ELF EMF, the variability of experimental data on biological effects of EMF, obtained in different laboratories, can be explained by different environmental conditions of experiments, which very often are not considered adequately.     

Bidirectional frequency-dependent effect of extremely low-frequency electromagnetic field on E. coli K-12

In the present work, the frequency-dependent effects of extremely low-frequency electromagnetic field (ELF EMF) on Escherichia coli K-12 growth have been studied. The frequency-dependent effects of ELF EMF have shown that it can either stimulate or inhibit the growth of microbes. However, the mechanism by which the ELF EMF affects the bacterial cells is not clear yet. It was suggested that the aqua medium can serve as a target through which the biological effect of ELF EMF on microbes may be realized. To check this hypothesis, the frequency-dependent effects (2, 4, 6, 8, 10 Hz, B = 0.4 mT, 30 min) of ELF EMF on the bacterial growth were studied in both cases where the microbes were in the culture media during the exposure and where culture media was preliminarily exposed to the ELF EMF before the addition of bacteria. For investigating the cell proliferation, the radioactive [³H]-thymidine assay was carried out. It has been shown that EMF at 4 Hz exposure has pronounced stimulation while at 8 Hz it has inhibited cell proliferation.     

Metabolic response ofDanaüs archippus andSaccharomyces cerevisiae to weak oscillatory magnetic fields

Respiration of the insect larva,Danaüs archippus, and the yeast,Saccharomyces cerevisiae, in log phase has been monitored before and after an oscillatory magnetic insult of 0.005 Gauss rms amplitude and 40–50 min duration. Frequencies used were 10–16 Hz for the insect and 100–200 Hz for the yeast. Depression of as much as 30% in metabolic rate has been found to occur immediately after the field is both imposed and eliminated with a general recovery over the 30-min period thereafter both in and out of the imposed field, although complete recovery to original levels may take much longer. Evidence is given that the response may depend on the frequency pattern used. This data is used to formulate an hypothesis whereby changes in the geomagnetic field variability pattern may act as a biochronometric zeitgeber.     

Acute exposure to high‐induction electromagnetic field affects activity of model peripheral sensory neurons

Exposure to repetitive low‐frequency electromagnetic field (LF‐EMF) shows promise as a non‐invasive approach to treat various sensory and neurological disorders. Despite considerable progress in the development of modern stimulation devices, there is a limited understanding of the mechanisms underlying their biological effects and potential targets at the cellular level. A significant impact of electromagnetic field on voltage‐gated calcium channels and downstream signalling pathways has been convincingly demonstrated in many distinct cell types. However, evidence for clear effects on primary sensory neurons that particularly may be responsible for the analgesic actions of LF‐EMF is still lacking. Here, we used F11 cells derived from dorsal root ganglia neurons as an in vitro model of peripheral sensory neurons and three different protocols of high‐induction magnetic stimulation to determine the effects on chemical responsiveness and spontaneous activity. We show that short‐term (<180 sec.) exposure of F11 cells to LF‐EMF reduces calcium transients in response to bradykinin, a potent pain‐producing inflammatory agent formed at sites of injury. Moreover, we characterize an immediate and reversible potentiating effect of LF‐EMF on neuronal spontaneous activity. Our results provide new evidence that electromagnetic field may directly modulate the activity of sensory neurons and highlight the potential of sensory neuron‐derived cell line as a tool for studying the underlying mechanisms at the cellular and molecular level.     

Changes of cationic transport in <Emphasis Type="Italic">AtCAX5</Emphasis> transformant yeast by electromagnetic field environments

The electromagnetic field (EMF) is newly considered as an exogenous environmental stimulus that is closely related to ion transportation on the cellular membrane, maintaining the internal ionic homeostasis. Cation transports of Ca²⁺ and other metal ions, Cd²⁺, Zn²⁺, and Mn²⁺were studied in terms of the external Ca²⁺ stress, [Ca²⁺]_ext, and exposure to the physical EMF. A specific yeast strain K667 was used for controlling CAX5 (cation/H⁺ exchanger) expression. Culture samples were exposed to 60 Hz, 0.1 mT sinusoidal or square magnetics waves, and intracellular cations of each sample were measured and analyzed. AtCAX5 transformant yeast grew normally under the metallic stress. However, the growth of the control group was significantly inhibited under the same cation concentration; 60 Hz and 0.1 mT magnetic field enhanced intracellular cation concentrations significantly as exposure time increased both in the AtCAX5 transformed yeast and in the control group. However, the AtCAX5-transformed yeast showed higher concentration of the intracellular cations than the control group under the same exposure EMF. AtCAX5-transformed yeasts displayed an increment in [Ca²⁺]_int, [K⁺]_int, [Na⁺]_int, and [Zn²⁺]_int concentration under the presence of both sinusoidal and square-waved EMF stresses compared to the control group, which shows that AtCAX5 expressed in the vacuole play an important role in maintaining the homeostasis of intracellular cations. These findings could be utilized in the cultivation of the crops which were resistant to excessive exogenous ions or in the production of biomass containing a large proportion of ions for nutritional food or in the bioremediation process in metal-polluted environments.     

Effects of extremely-law-frequency electromagnetic fields on ion transport in several mammalian cells

We have investigated the effects of sinusoidal electromagnetic fields (EMF) on ion transport (Ca²⁺, Na⁺, K⁺, and H⁺) in several cell types (red blood cells, thymocytes, Ehrlich ascites tumor cells, and HL60 and U937 human leukemia cells). The effects on the uptake of radioactive tracers as well as on the cytosolic Ca²⁺ concentration ([Ca²⁺]_i), the intracellular pH (pH_i), and the transmembrane potentsial (TMP) were studied. Exposure to EMF at 50 Hz and 100–2000 μT (rms) had no significant effects on any of these parameters. Exposure to EMF of 20–1200 μT (rms) at the estimated cyclotron magnetic resonance frequencies for the respective ions had no significant effects except for a 12–32% increase of the uptake of ⁴²K within a window at 14.5–15.5 Hz and 100–200 μT (rms), which was found in U937 and Ehrlich cells but not in the other cell types. © 1994 Wiley-Liss, Inc.     

The Short‐Term Effect of Occupational Levels of 50 Hz Electromagnetic Field on Human Heart Rate Variability

Previous studies have indicated that there is no consensus on the effects of extremely low‐frequency electromagnetic (ELF‐EMF) exposure on the cardiovascular system. This study aimed to explore the short‐term effect of ELF‐EMF exposure on heart rate (HR) and HR variability (HRV). The sample consisted of 34 healthy males aged 18–27 years. The participants were randomly assigned to the EMF (n = 17) or the Sham group (n = 17). We employed a double‐blind repeated‐measures design consisting of three 5 min experimental periods. The chest region of each individual in the EMF group was exposed to 50 Hz, 28 μT, linear polarized, continuous EMF during the EMF exposure period. HR and HRV data were recorded continuously by using a photoplethysmography sensor. Within‐subject statistical analysis indicated a significant HR deceleration in both the EMF and Sham groups. However, the standard deviation of the NN intervals (SDNN), root mean square of successive differences (RMSSD), low‐frequency (LF), and high‐frequency (HF) powers increased only in the EMF group and remained stable in the Sham group. We also compared the same HRV indices measured during the EMF and Sham periods between the two experimental groups. The between‐subject analysis results demonstrated significantly higher SDNN, RMSSD, LF, and HF values in the EMF group than in the Sham group. The LF/HF ratio did not change significantly within and between groups. On the basis of these results, we concluded that short‐term exposure of the chest region to ELF‐EMF could potentially enhance parasympathetic predominance during the resting condition. Bioelectromagnetics. 2021;42:60–75. © 2020 Bioelectromagnetics Society.     

In Vitro Evaluation of the Effects of Electromagnetic Fields used for Bone Healing

The use of therapeutic electromagnetic fields (EMF) for bone healing has positive clinical effects but may have adverse biologic effects. For this reason, EMF exposure has been repeatedly investigated to exclude the possibility of genotoxic effects and tumour risk. This paper describes the effects of EMFs on cell cultures. We analyzed the effects of EMF (28 gauss, 75 Hz) on growth and metabolic activities in four different cell types: L929 fibro-blasts, osteoblast-like HOS/TE85 cells, human lymphocytes, and rabbit chondrocytes. We found no cytotoxic or mutagenic effects on cultures exposed to EMF compared with unexposed controls. Results of cell proliferation showed a statistically significant increase for all cultures exposed to EMF with respect to controls (L929 +45%, p = 0.002; HOS/TE85 +32%, p = 0.001; chondrocytes +40%, p = 0.0003; lymphocytes +39%, p = 0.0002). Biochemical and enzymatic tests gave different results, depending on cell types: all tested values were increased after EMF exposure, even if only some of them reached statistical significance (total proteins: HOS/TE85 p = 0.004, chondrocytes p = 0.003; alkaline phosphatase: L929p = 0.0003, HOS/RE85 p = 0.0001, chondrocytes p = 0.009, lymphocytes p = 0.006; lactate dehydrogenase: chondrocytes p = 0.0002, lymphocytes p = 0.0005). Biochemical and enzymatic tests and cell proliferation results suggest a more active metabolism in cartilage and bone cells after EMF exposure. These effects could be relevant for bone healing in clinical practice.     

The production of ethanol by immobilized yeast cells

Saccharomyces cerevisiae cells were immobilized in calcium alginate beads for use in the continuous production of ethanol. Yeasts were grown in medium supplemented with ethanol to selectively screen for a culture which showed the greatest tolerance to ethanol inhibition. Yeast beads were produced from a yeast slurry containing 1.5% alginate (w/v) which was added as drops to 0.05M CaCl₂ solution. To determine their optimum fermentation parameters, ethanol production using glucose as a substrate was monitored in batch systems at varying physiological conditions (temperature, pH, ethanol concentration), cell densities, and gel concentration. The data obtained were compared to optimum free cell ethanol fermentation parameters. The immobilized yeast cells examined in a packed-bed reactor system operated under optimized parameters derived from batch-immobilized yeast cell experiments. Ethanol production rates, as well as residual sugar concentration were monitored at different feedstock flow rates.     

Robust metabolic responses to varied carbon sources in natural and laboratory strains of Saccharomyces cerevisiae

Understanding factors that regulate the metabolism and growth of an organism is of fundamental biologic interest. This study compared the influence of two different carbon substrates, dextrose and galactose, on the metabolic and growth rates of the yeast Saccharomyces cerevisiae. Yeast metabolic and growth rates varied widely depending on the metabolic substrate supplied. The metabolic and growth rates of a yeast strain maintained under long-term laboratory conditions was compared to strain isolated from natural condition when grown on different substrates. Previous studies had determined that there are numerous genetic differences between these two strains. However, the overall metabolic and growth rates of a wild isolate of yeast was very similar to that of a strain that had been maintained under laboratory conditions for many decades. This indicates that, at in least this case, metabolism and growth appear to be well buffered against genetic differences. Metabolic rate and cell number did not co-vary in a simple linear manner. When grown in either dextrose or galactose, both strains showed a growth pattern in which the number of cells continued to increase well after the metabolic rate began a sharp decline. Previous studied have reported that O₂ consumption in S. cerevisiae grown in reduced dextrose levels were elevated compared to higher levels. Low dextrose levels have been proposed to induce caloric restriction and increase life span in yeast. However, there was no evidence that reduced levels of dextrose increased metabolic rates, measured by either O₂ consumption or CO₂ production, in the strains used in this study.     

The dynamic behaviour of yeast cells immobilised in porous glass studied by membrane mass spectrometry

Membrane mass spectrometry (MMS) with reduced sample withdrawal has been used to investigate the metabolic activity of yeast cells immobilised in porous glass. An adapted MS membrane inlet reactor with a polyethylene terephthalate barrier membrane has been constructed for this purpose. In a first experiment, the mass transport of O₂ in a porous glass disc under well-defined experimental conditions has been studied by determining the apparent effective diffusion coefficient. The behaviour of immobilised Saccharomyces cerevisiae has been monitored by the MMS measurement of O₂ and CO₂ after applying a step in glucose concentration. Free-cell kinetic parameters were used in a dynamic reaction-diffusion model to simulate the O₂ consumption curve. The theoretical and experimental curve showed comparable behaviour, which means that the immobilisation of yeast cells in porous glass has no substantial effect on its growth kinetics.     

Elevated CO2 and O3 effects on ectomycorrhizal fungal root tip communities in consideration of a post-agricultural soil nutrient gradient legacy

Despite the critical role of EMF in nutrient and carbon (C) dynamics, combined effects of global atmospheric pollutants on ectomycorrhizal fungi (EMF) are unclear. Here, we present research on EMF root-level community responses to elevated CO₂ and O₃. We discovered that belowground EMF community richness and similarity were both negatively affected by CO₂ and O₃, but the effects of CO₂ and O₃ on EMF communities were contingent on a site soil pH and cation availability gradient. These results contrast with our previous work showing a strong direct effect of CO₂ and O₃ on sporocarp community dynamics and production. We discuss the possible role of carbon demand and allocation by EMF taxa in the discrepancy of these results. EMF communities were structured by a legacy of spatially defined soil properties, changing atmospheric chemistry and temporal dynamics. It is therefore necessary to understand global change impacts across multiple environmental gradients and spatiotemporal scales.     

Orientation response of haematophagous bugs to CO2: the effect of the temporal structure of the stimulus

Carbon dioxide is generally recognized as an important cue used by haematophagous insects to locate a food source. When the mammalian hosts of these insects breathe, they normally emanate considerable amounts of CO₂ at discrete intervals, i.e. with each exhalation. In this work, we analysed the effect of temporally pulsing CO₂ on the host-seeking behaviour of Triatoma infestans. We investigated the ability of T. infestans to follow continuous and intermittent air pulses of 0.25, 0.5 and 1 Hz that included different concentrations of CO₂. We found that insects were attracted to pulsed airstreams of 0.25 and 0.5 Hz transporting 400 ppm of CO₂ above the ambient levels and to continuous streams added with the same amount of CO₂. On the other hand, insects walked away from streams pulsed at rates of 1 Hz regardless of the amount of CO₂ they bear. The walking trajectories displayed by bugs to attractive CO₂-pulsed streams were as rectilinear and accurate as those to CO₂-continuous streams. Our results are discussed in the frame of the interaction between olfactory and mechanoreceptive inputs as affecting the behavioural response of bugs.     

Perception of the electromagnetic field emitted by a mobile phone

Electromagnetic sensibility refers to the ability to perceive the electromagnetic field (EMF) without necessarily developing health symptoms attributed to EMF exposure. A large sample of young healthy adults (n = 84) performed two forced‐choice tasks on the perception of the GSM mobile phone EMF (902 MHz pulsed at 217 Hz), “Was the field on?” and “Did the field change?” (3 conditions × 100 trials for each task, n = 600 trials in total). A monetary prize was announced for good performance (correct response rate ≥75%, n = 600 trials). The performance was no better than expected by chance, and thus none of the participants won the prize. Two participants showed extraordinary performance in one of the task conditions (“Was the field on?”, n = 100 trials), with correct response rates of 97% (P = 1.28 × 10^?25) and 94% (P = 9.40 × 10^?22), but they failed to replicate the result in the retest of six blocks of the same condition 1 month later. Six participants had reported being able to perceive the mobile phone EMF in the preliminary inquiry, but they performed no better than the others. This study provides empirical evidence against the existence of electromagnetic sensibility to the mobile phone EMF, demonstrating the necessity for replication in EMF studies. Bioelectromagnetics 29:154–159, 2008. © 2007 Wiley‐Liss, Inc.     

Effects of immersion in water containing high concentrations of CO2 (CO2-water) at thermoneutral on thermoregulation and heart rate variability in humans

Immersion in high concentrations of CO₂ dissolved in freshwater (CO₂-water) might induce peripheral vasodilatation in humans. In this study, we investigated whether such immersion could affect the autonomic nervous system in humans using spectral analysis of heart rate variability. Ten healthy men participated in this study. Tympanic temperature, cutaneous blood flow and electrocardiogram (ECG) were measured continuously during 20 min of immersion in CO₂-water. The ECG was analyzed by spectral analysis of R–R intervals using the maximal entropy method. The decrease in tympanic temperature was significantly greater in CO₂-water immersion than in freshwater immersion. Cutaneous blood flow at the immersed site was significantly increased with CO₂-water immersion compared to freshwater. The high frequency component (HF: 0.15–0.40 Hz) was significantly higher in CO₂-water immersion than in freshwater immersion, but the low frequency (LF: 0.04–0.15 Hz) /high frequency ratio (LF/HF ratio) was significantly lower in CO₂-water immersion than in freshwater immersion. The present study contributes evidence supporting the hypothesis that CO₂-water immersion activates parasympathetic nerve activity in humans.     

Carbon dioxide balance of a fen ecosystem in northern Finland under elevated UV-B radiation

The effect of elevated UV‐B radiation on CO₂ exchange of a natural flark fen was studied in open‐field conditions during 2003–2005. The experimental site was located in Sodankylä in northern Finland (67°22′N, 26°38′E, 179 m a.s.l.). Altogether 30 study plots, each 120 cm × 120 cm in size, were randomly distributed between three treatments (n=10): ambient control, UV‐A control and UV‐B treatment. The UV‐B‐treated plots were exposed to elevated UV‐B radiation level for three growing seasons. The instantaneous net ecosystem CO₂ exchange (NEE) and dark respiration (R_TOT) were measured during the growing season using a closed chamber method. The wintertime CO₂ emissions were estimated using a gradient technique by analyzing the CO₂ concentration in the snow pack. In addition to the instantaneous CO₂ exchange, the seasonal CO₂ balances during the growing seasons were modeled using environmental data measured at the site. In general, the instantaneous NEE at light saturation was slightly higher in the UV‐B treatment compared with the ambient control, but the gross photosynthesis was unaffected by the exposure. The R_TOT was significantly lower under elevated UV‐B in the third study year. The modeled seasonal (June–September) CO₂ balance varied between the years depending on the ground water level and temperature conditions. During the driest year, the seasonal CO₂ balance was negative (net release of CO₂) in the ambient control and the UV‐B treatment was CO₂ neutral. During the third year, the seasonal CO₂ uptake was 43±36 g CO₂‐C m⁻² in the ambient control and 79±45 g CO₂‐C m⁻² in the UV‐B treatment. The results suggest that the long‐term exposure to high UV‐B radiation levels may slightly increase the CO₂ accumulation to fens resulting from a decrease in microbial activity in peat. However, it is unlikely that the predicted development of the level of UV‐B radiation would significantly affect the CO₂ balance of fen ecosystems in future.