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1.
Effects of two types of low-intensity electromagnetic fields (EMF) of industrial frequency (50 Hz) on the fine structure and proliferative activity of thymic cells in white rats were studied. It was found that a weak EMF with a prevailing electrical component (380-480 V/m, 120-140 nT1) did not affect the DNA synthesis intensity. An EMF with a stronger magnetic induction (10-15 V/m, 800-1500 nT1) diminished the glucose-6-phosphate dehydrogenase activity and proliferative processes in cultured stimulated lymphocytes. Electron microscopic investigation of the thymus after both types of exposure revealed an accumulation of lymphocytes with pyknotic nuclei and electron-dense cytoplasm, as well as hypoplasia of the vascular endothelium. At the same time, EMF with a prevailing magnetic component produced a more marked negative effect on the ultrastructure of thymic cells, which indicated a lowered secretory activity of epitheliocytes.  相似文献   

2.
Previous investigations of exposure to electric, magnetic, or electromagnetic fields (EMF) in households were either about electricity supply EMFs or radio frequency EMFs (RF‐EMFs). We report results from spot measurements at the bedside that comprise electrostatic fields, extremely low‐frequency electric fields (ELF‐EFs), extremely low‐frequency magnetic fields (ELF‐MFs), and RF‐EMFs. Measurements were taken in 226 households throughout Lower Austria. In addition, effects of simple reduction measures (e.g., removal of clock radios or increasing their distance from the bed, turning off Digital Enhanced Cordless Telecommunication (DECT) telephone base stations) were assessed. All measurements were well below International Commission on Non‐Ionizing Radiation Protection (ICNIRP) guideline levels. Average night‐time ELF‐MFs (long‐term measurement from 10 pm to 6 am, geometric mean over households) above 100 nT were obtained in 2.3%, and RF‐EMFs above 1000 µW/m2 in 7.1% of households. Highest ELF‐EFs were primarily due to lamps beside the bed (max = 166 V/m), and highest ELF‐MFs because of transformers of devices (max = 1030 nT) or high current of power lines (max = 380 nT). The highest values of RF‐EMFs were caused by DECT telephone base stations (max = 28979 µW/m2) and mobile phone base stations (max = 4872 µW/m2). Simple reduction measures resulted in an average decrease of 23 nT for ELF‐MFs, 23 V/m for ELF‐EFs, and 246 µW/m2 for RF‐EMFs. A small but statistically significant correlation between ELF‐MF exposure and overall RF‐EMF levels of R = 0.16 (P = 0.008) was computed that was independent of type (flat, single family) and location (urban, rural) of houses. Bioelectromagnetics 31:200–208, 2010. © 2009 Wiley‐Liss, Inc.  相似文献   

3.
The production of spindle disturbances in a human–hamster hybrid (AL) cell line by an electromagnetic field (EMF) with field strength of 90 V/m at a frequency of 900 MHz was studied in greater detail. The experimental setup presented allows investigating whether either the electrical (E) and/or the magnetic (H) field component of EMF can be associated with the effectiveness of the spindle‐disturbing potential. Therefore, both field components of a transversal electromagnetic field (TEM) wave have been separated during exposure of the biological system. This procedure should give more insight on understanding the underlying mechanisms of non‐thermal effects of EMF. A statistical comparison of the proportions of the fractions of ana‐ and telophases with spindle disturbances, obtained for five different exposure conditions with respect to unexposed controls (sham condition), showed that only cells exposed to the H‐field component of the EMF were not different from the control. Therefore, the results of the present study indicate that an exposure of cells to EMF at E‐field strengths of 45 and 90 V/m, as well as to the separated E component of the EMF, induces significant spindle disturbances in ana‐ and telophases of the cell cycle. Bioelectromagnetics 32:291–301, 2011. © 2010 Wiley‐Liss, Inc.  相似文献   

4.
Plant–soil feedbacks have been observed in many forest communities, but the role of the mycorrhizal community in perpetuating feedback loops is still poorly understood. Mycorrhizal community composition is closely linked to soil properties and host plant composition, which highlights their potential importance in plant–soil–fungus loops. Eastern hemlock (hemlock; Tsuga canadensis) seedlings were grown in soil bioassays in growth chambers and transplanted under closed forest canopy to examine the effect of hardwood and hemlock forest soil on seedling growth, survival, and ectomycorrhizal fungi (EMF) colonization. Seedlings propagated in hemlock forest soil had greater height growth compared with sterile control soil and achieved greater mycorrhizal colonization than seedlings grown in hardwood forest soils after 9 months in a growth chamber. Outplanted seedlings grown in hemlock communities achieved significantly greater increment growth than those seedlings grown in hardwood communities (mean height difference (95% CI)?=?0.39 cm (0.14–0.63 cm)), although final survival and EMF colonization was similar between forest types. EMF diversity (Shannon-Wiener index (SE)?=?1.88 (0.28) and 1.23 (0.44) for hardwood and hemlock, respectively) and community assemblage (Jaccard index (SE)?=?19.0% (4%)) differed between the two forest communities. EMF community assemblage was associated with both the forest type (i.e. plant community/microsite effects) and initial soil type (i.e. soil characteristics/resistant inoculum). The results support previously observed positive feedbacks between conspecifics under hemlock forest communities and provides evidence for the role of the EMF community within this feedback loop. Alternatively, the reduced growth of hemlocks under hardwoods may be attributed to the different EMF community associated with that forest.  相似文献   

5.
Large numbers of bats are killed by collisions with wind turbines, and there is at present no direct method of reducing or preventing this mortality. We therefore determine whether the electromagnetic radiation associated with radar installations can elicit an aversive behavioural response in foraging bats. Four civil air traffic control (ATC) radar stations, three military ATC radars and three weather radars were selected, each surrounded by heterogeneous habitat. Three sampling points matched for habitat type and structure, dominant vegetation species, altitude and surrounding land class were located at increasing distances from each station. A portable electromagnetic field meter measured the field strength of the radar at three distances from the source: in close proximity (<200 m) with a high electromagnetic field (EMF) strength >2 volts/metre, an intermediate point within line of sight of the radar (200-400 m) and with an EMF strength <2 v/m, and a control site out of sight of the radar (>400 m) and registering an EMF of zero v/m. At each radar station bat activity was recorded three times with three independent sampling points monitored on each occasion, resulting in a total of 90 samples, 30 of which were obtained within each field strength category. At these sampling points, bat activity was recorded using an automatic bat recording station, operated from sunset to sunrise. Bat activity was significantly reduced in habitats exposed to an EMF strength of greater than 2 v/m when compared to matched sites registering EMF levels of zero. The reduction in bat activity was not significantly different at lower levels of EMF strength within 400 m of the radar. We predict that the reduction in bat activity within habitats exposed to electromagnetic radiation may be a result of thermal induction and an increased risk of hyperthermia.  相似文献   

6.
We tested if root colonisation by ectomycorrhizal fungi (EMF) could alter the susceptibility of Norway spruce (Picea abies) seedlings to root rot infection or necrotic foliar pathogens. Firstly, spruce seedlings were inoculated by various EMF and challenged with Heterobasidion isolates in triaxenix tubes. The ascomycete EMF Meliniomyces bicolor, that had showed strong antagonistic properties towards root rot causing Heterobasidion in vitro, protected spruce seedlings effectively against root rot. Secondly, spruce seedlings, inoculated with M. bicolor or the forest humus, were subjected to necrotrophic foliar pathogens in conventional forest nursery conditions on peat substrates. Botrytis cinerea infection after winter was mild and the level of needle damage was independent of substrate and EMF colonisation. Needle damage severity caused by Gremminiella abietina was high in seedlings grown in substrates with high nutrient availability as well as in seedlings with well-established EMF communities. These results show that albeit M. bicolor is able to protect spruce seedlings against Heterobasidion root rot in axenic cultures it fails to induce systemic protection against foliar pathogens. We also point out that unsterile inoculum sources, such as the forest humus, should not be considered for use in greenhouse conditions as they might predispose seedlings to unintended needle damages.  相似文献   

7.
Starch obtained from yellow and white plantain varieties were subjected to proximate analysis, physicochemical and rheological characterization in order to evaluate their properties. Yellow plantain variety gave higher yield of starch than the white variety. The two varieties differed in the purity of starch extract; white plantain starch contained: ash (1.09%), protein (0.640%) and fat (0.276%) while yellow plantain starch contained: ash (0.95%), protein (0.325%) and fat (0.403%). The amylose content of yellow plantain starch (24.36% (apparent), 26.13% (total)) was similar to that of white plantain starch (24.24% (apparent), 26.01% (total)). Scanning electron microscopy revealed bimodal irregular shaped granules (3.74–7.00 and 10.00–33.00 μm) in white plantain starch and elliptical granules (11.22–41.00 μm) in yellow plantain starch. Both starches differed markedly in their physicochemical properties. Their differences in gelatinization temperature (yellow plantain, 64.99–73.90 °C; white plantain, 68.08–77.15 °C), swelling and solubility patterns, and pasting characteristics indicated that yellow plantain starch had weaker granule architecture compared with white plantain starch. Further evidence of differences in properties was obtained from flow and viscoelastic properties of the starch gels, paste clarity and freeze–thaw stability.  相似文献   

8.
Ectomycorrhizal fungal (EMF) communities vary among microhabitats, supporting a dominant role for deterministic processes in EMF community assemblage. EMF communities also differ between forest and clearcut environments, responding to this disturbance in a directional manner over time by returning to the species composition of the original forest. Accordingly, we examined EMF community composition on roots of spruce seedlings planted in three different microhabitats in forest and clearcut plots: decayed wood, mineral soil adjacent to downed wood, or control mineral soil, to determine the effect of retained downed wood on EMF communities over the medium and long term. If downed and decayed wood provide refuge habitat distinct from that of mineral soil, we would expect EMF communities on seedlings in woody habitats in clearcuts to be similar to those on seedlings planted in the adjacent forest. As expected, we found EMF species richness to be higher in forests than clearcuts (P ≤ 0.01), even though soil nutrient status did not differ greatly between the two plot types (P ≥ 0.05). Communities on forest seedlings were dominated by Tylospora spp., whereas those in clearcuts were dominated by Amphinema byssoides and Thelephora terrestris. Surprisingly, while substrate conditions varied among microsites (P ≤ 0.03), especially between decayed wood and mineral soil, EMF communities were not distinctly different among microhabitats. Our data suggest that niche partitioning by substrate does not occur among EMF species on very young seedlings in high elevation spruce-fir forests. Further, dispersal limitations shape EMF community assembly in clearcuts in these forests.  相似文献   

9.
In a shadehouse experiment we tested the effects of light, nutrients and ectomycorrhizal fungi (EMF) on the growth of Vatica albiramis van Slooten (Dipterocarpaceae) seedlings. We hypothesised that it is more advantageous for plants to form connections with EMF and to trade carbon for nutrients with EMF under high light than low light. The relationship between seedling growth and the proportion of ectomycorrhizal root tips was expected as positive in high light and as negative in low light. Light conditions simulated the forest understory (low; 3% full sunlight), a small gap (medium; 11%) and a large gap (high; 33%) and a fully factorial combination of nutrients (F?/+) and ectomycorrhizal colonization (EMF?/+) treatments were applied within light conditions. The application of EMF and nutrients did significantly alter seedling growth across the range of forest floor light conditions, however the key hypothesis was rejected as seedling growth under low light was not affected by increased EMF colonization of root tips (light:EMF colonization χ2?=?2.97, p?=?0.23). In addition, the lack of difference in morphotype abundance across light conditions indicated that light changes may not favour the association to specific EMF in seedlings of this particular dipterocarp species. Our results suggest that antagonistic (non-beneficial to the plant) effects due to ectomycorrhizal colonization under a light constrained environment may not affect seedling growth of Vatica albiramis.  相似文献   

10.
The influence of mature trees on colonization of Douglas-fir (Pseudotsuga menziesii) seedlings by ectomycorrhizal fungi (EMF) is not well understood. Here, the EMF communities of seedlings planted near and far from trees are compared with each other, with EMF of seedlings potted in field soils and with EMF of mature trees. Seedlings were planted within 6 m, or beyond 16 m, from residual Douglas-fir trees in recently harvested green-tree retention units in Washington State, USA, or potted in soils gathered from near each residual tree. Mature tree roots were sampled by partly excavating the root system. The EMF communities were assessed by polymerase chain reaction-restriction fragment length polymorphism and sequence analysis of ribosomal RNA genes. Seedlings near trees had higher species richness and diversity of EMF communities compared with seedlings far from trees. The EMF communities of seedlings near trees were more similar to those of mature trees, while seedlings far from trees were more similar to glasshouse seedlings. By enhancing the EMF diversity of seedlings, residual trees may maintain or accelerate the re-establishment of mycorrhizal communities associated with mature forests.  相似文献   

11.
A sub‐acute electromagnetic field (EMF) biological effect study was carried out on rats exposed in the Transverse ElectroMagnetic exposure chamber at 171 MHz Continuous Wave (CW). The experiments involved three exposure levels (15, 25, and 35 V/m) for 15 days with triplicate parallel sham‐exposed controls in each series. All exposure conditions were simulated for the evaluation of the electromagnetic energy distribution and specific absorption rate (SAR) in the rat phantoms. Studies have shown a biphasic biological response depending on time and absorbed electromagnetic energy. Under low SAR, approximately 0.006 W/kg, EMF exposure leads to the stimulation of adrenal gland activity. This process is accompanied by an initial increase of daily excretion of corticosterone and Na+, which is seen as a higher Na+/K+ ratio, followed by a decrease of these parameters over time. It is possible that EMF exposure causes a stress response in animals, which is seen as an increased adrenal activity. Bioelectromagnetics. 2019;40:578–587. © 2019 Bioelectromagnetics Society.  相似文献   

12.
The influence of magnetic resonance imaging (MRI) devices at high field strengths on living tissues is unknown. We investigated the effects of a 3-tesla electromagnetic field (EMF) on the biosynthetic activity of bovine articular cartilage. Bovine articular cartilage was obtained from juvenile and adult animals. Whole joints or cartilage explants were subjected to a pulsed 3-tesla EMF; controls were left unexposed. Synthesis of sulfated glycosaminoglycans (sGAGs) was measured by using [35S]sulfate incorporation; mRNA encoding the cartilage markers aggrecan and type II collagen, as well as IL-1β, were analyzed by RT–PCR. Furthermore, effects of the 3-tesla EMF were determined over the course of time directly after exposure (day 0) and at days 3 and 6. In addition, the influence of a 1.5-tesla EMF on cartilage sGAG synthesis was evaluated. Chondrocyte cell death was assessed by staining with Annexin V and TdT-mediated dUTP nick end labelling (TUNEL). Exposure to the EMF resulted in a significant decrease in cartilage macromolecule synthesis. Gene expression of both aggrecan and IL-1β, but not of collagen type II, was reduced in comparison with controls. Staining with Annexin V and TUNEL revealed no evidence of cell death. Interestingly, chondrocytes regained their biosynthetic activity within 3 days after exposure, as shown by proteoglycan synthesis rate and mRNA expression levels. Cartilage samples exposed to a 1.5-tesla EMF remained unaffected. Although MRI devices with a field strength of more than 1.5 T provide a better signal-to-noise ratio and thereby higher spatial resolution, their high field strength impairs the biosynthetic activity of articular chondrocytes in vitro. Although this decrease in biosynthetic activity seems to be transient, articular cartilage exposed to high-energy EMF may become vulnerable to damage.  相似文献   

13.
This study was designed to test whether extremely low frequency electromagnetic field (ELF‐EMF) could enhance the apoptosis‐induction effect of X‐ray radiotherapy on liver cancer cell line BEL‐7402 in vitro. EMF exposure was performed inside an energized solenoid coil. X‐ray irradiation was performed using a linear accelerator. Apoptosis rates of BEL‐7402 cells were analyzed using Annexin V‐Fit Apoptosis Detection kit. Apoptosis rates of EMF group and sham EMF group were compared when combined with X‐ray irradiation. Our results suggested that the apoptosis rate of BEL‐7402 cells exposed to low doses of X‐ray irradiation could be significantly increased by EMF. More EMF exposures obtain significantly higher apoptosis rates than fewer EMF exposures when combined with 2 Gy X‐ray irradiation. These findings suggested that ELF‐EMF could augment the cell apoptosis effects of low doses of X‐ray irradiation on BEL‐7402 cells in a synergistic and cumulative way. Bioelectromagnetics 30:163–165, 2009. © 2008 Wiley‐Liss, Inc.  相似文献   

14.
The main purpose of this work was to investigate the fluctuation of Greek indoor electromagnetic field (EMF) intensity values and identify peaks that might occur. The scientific interest is mainly focused on the bands of extremely low-frequency (ELF) magnetic fields and radiofrequency (RF) electric fields which have been suggested to be possibly carcinogenic to humans by the Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR).Electromagnetic radiation (EMR) measurements were performed in a variety of indoor dwellings, in Attica and in the islands of Zakynthos and Lesvos.A total number of 4540 measurements were taken in a wide frequency range (50 Hz–2100 MHz) of which 3301 in Attica, 963 in Lesvos and 276 in Zakynthos.Statistical analysis of the data revealed specific statistically significant differences between the mean values of the electric (ELF and RF) but not the magnetic (ELF) field strengths measured at different distances from the EMF source, as well as between some of the mean values of the RF electric field at different bands. Some statistically significant differences between mean electric field values at different geographic locations were also identified.As far as the RF electric field is concerned, the maximum values, in most cases, were below 0.5 V/m, however increased values above 1 V/m and up to 5.6 V/m were occasionally observed. The ELF magnetic field values were lower than 1 μT. It may be concluded that overall, the observed indoor EMF intensity values remained well below domestic and European established limits.  相似文献   

15.
Wildfire severity in forests is projected to increase with warming and drying conditions associated with climate change. Our objective was to determine the impact of wildfire and clearcutting severity on the ectomycorrhizal fungal (EMF) community of Douglas-fir seedlings in the dry forests of interior British Columbia, Canada. We located our study within and surrounding the area of the McLure fire (August 2003). We hypothesized that disturbance would affect EMF community assembly due to reductions in fungal inoculum. Five treatments representing a range of disturbance severities were compared: high severity burn, low severity burn, screefed clearcut (manual removal of forest floor), clearcut, and undisturbed forest. EMF communities in the undisturbed forest were more complex than those in all disturbance treatments. However, aspects of community assembly varied with disturbance type, where the burn treatments had the simplest communities. After 4 months, regenerating seedlings in the burn treatments had the lowest colonization, but seedlings in all treatments were fully colonized within 1 year. EMF communities were similar among the four disturbance types, largely due to dominance of Wilcoxina throughout the study period. However, forest floor retention influenced community assembly as the EMF in the clearcut treatment, where forest floor was retained, had levels of diversity and richness comparable to the undisturbed forest. Overall, the results suggest that increasing forest floor disturbance can alter EMF community assembly in the first year of regeneration. A correlation between poorly colonized seedlings and seedling productivity also suggests a role for productivity in influencing community assembly.  相似文献   

16.
Pollen of Antirrhinum majus was irradiated with radiowaves (γ = 1.5 m; field strength 1.5 V/m) in 3 series for 4, 12 and 43 34 h, then crossed on styles of emasculated untreated flowers. After selfing of the M1 generation an increase in embryonic lethality and in mutations for characters of the seedlings and young plants was observed. These observations confirmed the mutagenic action of the treatment that was described earlier in Vicia faba and Oenothera hookeri.  相似文献   

17.
The aim of this study was to elucidate the possible effects of short‐term exposure to a 1439‐MHz electromagnetic field (EMF) employing time division multiple access (TDMA), which is the basis of the Japanese Personal Digital Cellular system, on estrogenic activity in rats. Sixty‐four ovariectomized female Sprague–Dawley rats were divided into four groups: EMF exposure (EM), sham exposure, cage control, and 17 beta‐estradiol injected (E2). The EM group was exposed, for 4 h per day on three consecutive days, to the 1439‐MHz TDMA signal that produced 5.5–6.1 and 0.88–0.99 W/kg average specific absorption rates in the brain and the whole body, respectively. The uterine wet mass and serum estradiol level significantly increased in the E2 group, while there were no differences among the other three groups. Although negative effects of long‐term EMF exposure must be thoroughly investigated before a final conclusion can be reached, our results do not support the assumption that the high frequency EMF used in cellular phones exerts estrogenic activity. Bioelectromagnetics 31:573–575, 2010. © 2010 Wiley‐Liss, Inc.  相似文献   

18.
To investigate possible health effects of mobile phone use, we conducted a double-blind, cross-over provocation study to confirm whether subjects with mobile phone related symptoms (MPRS) are more susceptible than control subjects to the effect of electromagnetic fields (EMF) emitted from base stations. We sent questionnaires to 5,000 women and obtained 2,472 valid responses from possible candidates; from these, we recruited 11 subjects with MPRS and 43 controls. There were four EMF exposure conditions, each of which lasted 30 min: continuous, intermittent, and sham exposure with and without noise. Subjects were exposed to EMF of 2.14 GHz, 10 V/m (W-CDMA), in a shielded room to simulate whole-body exposure to EMF from base stations, although the exposure strength we used was higher than that commonly received from base stations. We measured several psychological and cognitive parameters pre- and post-exposure, and monitored autonomic functions. Subjects were asked to report on their perception of EMF and level of discomfort during the experiment. The MPRS group did not differ from the controls in their ability to detect exposure to EMF; nevertheless they consistently experienced more discomfort, regardless of whether or not they were actually exposed to EMF, and despite the lack of significant changes in their autonomic functions. Thus, the two groups did not differ in their responses to real or sham EMF exposure according to any psychological, cognitive or autonomic assessment. In conclusion, we found no evidence of any causal link between hypersensitivity symptoms and exposure to EMF from base stations.  相似文献   

19.
Abstract

The growing spread of mobile phone use is raising concerns about the effect on human health of the electromagnetic field (EMF) these devices emit. The purpose of this study was to investigate the effects on rat pup heart tissue of prenatal exposure to a 900 megahertz (MHz) EMF. For this purpose, pregnant rats were divided into experimental and control groups. Experimental group rats were exposed to a 900?MHz EMF (1?h/d) on days 13–21 of pregnancy. Measurements were performed with rats inside the exposure box in order to determine the distribution of EMF intensity. Our measurements showed that pregnant experimental group rats were exposed to a mean electrical field intensity of 13.77?V/m inside the box (0.50?W/m2). This study continued with male rat pups obtained from both groups. Pups were sacrificed on postnatal day 21, and the heart tissues were extracted. Malondialdehyde, superoxide dismutase and catalase values were significantly higher in the experimental group rats, while glutathione values were lower. Light microscopy revealed irregularities in heart muscle fibers and apoptotic changes in the experimental group. Electron microscopy revealed crista loss and swelling in the mitochondria, degeneration in myofibrils and structural impairments in Z bands. Our study results suggest that exposure to EMF in the prenatal period causes oxidative stress and histopathological changes in male rat pup heart tissue.  相似文献   

20.
The ability of extremely low, time-varying electromagnetic field (EMF) to improve germination efficacy was studied in Foxtail millet (Setaria italica) seeds using response surface methodology. An optimal factorial central composite design was chosen to optimize the EMF with three critical factors, viz. frequency, intensity, and duration. The adequacy of the model and fitness was evaluated by analysis of variance and regression coefficients. This model suggested that the factors, frequency, and intensity had a significant impact on germination. Optimal conditions for germination were observed to be 10 Hz frequency, 30,007 nT intensity, and 30-min duration with an observed germination percentage of 93.0, and a predicted germination percentage of 92.92. Magneto-priming was found to increase the germination efficacy (15.66%), shoot length (27.78%), total seedling length (20.30%), seedling dry mass (26.49%), and water uptake (34.48% at 80 min) showing significant output when compared with the control and positive controls. Remarkable improvements were observed in germination parameters such as vigor index-1 (39.14%), vigor index-2 (46.28%), speed of germination (27.52%), and emergence index (12.50%). Magneto-priming was found to reduce the levels of germination-specific enzymes, viz. α-amylase, protease, and dehydrogenase, while it enhanced the levels of antioxidant enzymes, viz. catalase (114.63%) and superoxide dismutase (19.62%), triggering fast germination and early vigor of seedlings. This study clearly showed that EMF priming significantly improved the germination effect and other characteristics of Foxtail millet seeds. Bioelectromagnetics. © 2020 Bioelectromagnetics Society  相似文献   

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