Chen G, Lu D, Chiang H, Leszczynski D, Xu Z. · 2012
Researchers used the yeast Saccharomyces cerevisiae to study how exposure to extremely low frequency magnetic fields and radiofrequency EMF affects gene expression. Yeast cells were exposed for 6 hours to either 0.4 mT 50 Hz ELF-MF or 1800 MHz RF-EMF at a specific absorption rate of 4.7 W/kg. The study found no confirmed gene expression changes from ELF-MF exposure, and only the expressions of SMC3 and AQY2 were confirmed as responsive to RF-EMF.
Unknown authors · 2011
Researchers exposed E. coli GE499 cells to a combination of static and extremely low frequency magnetic fields and measured chromatin conformation using the anomalous viscosity time dependence technique, as well as cell growth, cloning efficiency, and SOS response. Nalidixic acid at 3-30 μg/ml decreased AVTD peaks, caused cytotoxic effects, and induced SOS response. ELF exposure increased AVTD, stimulated cell growth, and increased cloning efficiency, with these effects depending on frequency within the 7-11 Hz range. ELF exposure did not induce the recA-lacZ fusion and did not modify the genotoxic effects of nalidixic acid. The article was retracted in 2014, with a retraction notice in Mutat Res Genet Toxicol Environ Mutagen on January 15, 2014.
Unknown authors · 2011
Researchers exposed two Escherichia coli model systems 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). Transposition of both mini-Tn10 and Tn5 decreased under SiMF and increased under PMF compared to sham exposure control. No significant difference was found between frequencies and between exposure times.
Verschaeve L et al · 2011
Researchers performed a genotoxicity investigation of extremely low-frequency magnetic fields at 50 Hz, 100 and 500 µT, for 1 and 2 hours exposure, alone and with chemical mutagens using the VITOTOX test. The study showed that ELF magnetic fields do not induce SOS-based mutagenicity in S. typhimurium and do not show any synergetic effect when combined with chemical mutagens.
Unknown authors · 2011
Researchers exposed Spirostomum ambiguum infusoria to 1 GHz radiofrequency at energy flow densities of 5 μW/cm(2) and 50 μW/cm(2). Both exposure levels caused a reduction in motor activity that appeared in a jump-wise manner after a certain exposure duration and did not increase with longer exposure. The safe exposure duration was 8-9 h and 10 min at 5 and 50 μW, respectively.
Unknown authors · 2010
Researchers exposed wild-type and DNA-repair-deficient Saccharomyces cerevisiae strains to a 2.45 mT, 50 Hz sinusoidal magnetic field for 96 hours. Growth increased significantly in the rad52 strain and nearly significantly in the rad52 hdf1 strain. Survival was lower in all magnetic-field-exposed strains compared with controls, with the overall difference close to statistical significance. Cell cycle progression and DNA patterns were unchanged in all strains after exposure.
Unknown authors · 2010
Researchers exposed H. pylori ATCC 43629 cultures and 2-day-old biofilm to ELF-EMF at 50 Hz and 1 mT for 2 days. Exposed cultures and sham-exposed controls were studied for cell viability, morphology, biofilm mass, genotypic profile, and luxS and amiA gene expression. During biofilm formation, ELF-EMF exposure significantly increased spiral forms to 58.41% versus 33.14% in controls and reduced biofilm cell mass. On mature biofilm, no significant differences were found compared to controls, though biofilm mass was also reduced. No changes in DNA patterns were recorded, but amiA gene expression was modulated.
Unknown authors · 2009
Researchers investigated whether ELF-MF exposure could increase DnaK and GroEL protein levels in E. coli cells that lack a classic heat shock response. The cells showed enhanced DnaK and GroEL protein levels after 30 or 90 minutes of sinusoidal 50 Hz, 1 mT ELF-MF exposure. The result suggests the HSP induction pathway from ELF-MF exposure may differ from the heat shock pathway.
Unknown authors · 2008
Researchers exposed Escherichia coli ATCC 700926 to 50 Hz electromagnetic fields at 0.1, 0.5, and 1.0 mT and compared them with sham-exposed controls. Exposed and control samples had similar total and culturable counts. Exposed samples showed increased cell viability after 24 hours of re-incubation outside the solenoid. Exposure for 20–120 minutes caused significant morphological changes including coccoid cells and atypical lengthened forms. DNA fingerprinting showed no changes, while RNA-AFLP analysis revealed some differences at each field intensity.
Unknown authors · 2006
Unknown authors · 2005
Researchers studied singlet oxygen production sensitized by chemically modified, carotenoidless bacterial photosynthetic reaction centres. Both the singlet oxygen yield and the ensuing oxidative damage were shown to depend on magnetic field.
Unknown authors · 2004
Researchers investigated effects of magnetic fields from permanent magnets on different DNA sources in vivo and in vitro. They used Escherichia coli DNA, plasmid, and amplification products of different lengths as targets. In vivo assays showed no DNA alterations, while in vitro assays showed magnetic field exposure induces point mutations.
Unknown authors · 2004
Researchers exposed Escherichia coli strain XL-1Blue to a 300mT static magnetic field from permanent neodymium disks. They measured biomass by visible-light spectrometry and gene expression by RNA arbitrarily primed PCR. Exposed cells showed increased proliferation and changes in gene expression compared with controls. Three cDNAs were expressed only in exposed cells, one cDNA was more expressed in controls, and one exposed-only clone matched a putative transposase.
Cranfield CG, Wieser HG, Dobson J. · 2003
Researchers exposed magnetic bacteria to simulated mobile phone RF radiation and found no impact on mortality. Repeat experiments with only the GSM RF component in a waveguide system showed no significant change in cell mortality compared to sham exposures. A nonmagnetite control strain also showed no significant change in mortality between RF and sham samples.
Unknown authors · 2000
Researchers used a bacterial conjugation assay with Escherichia coli carrying the transposable element Tn5 as the donor strain. Donor cultures exposed to a 50 Hz, 1.2 mT magnetic field showed stimulated transposition of chromosomal Tn5 to an extrachromosomal episome and subsequent transfer to recipient cells. The transposition increase was mediated by induced synthesis and accumulation of the heat shock proteins DnaK/J. Magnetic field exposure was found to be stimulatory to transposition activity, similar to heat shock and UV irradiation.
Unknown authors · 2000
Researchers used Escherichia coli strain XL-1 Blue as the host and hydroxylamine-mutagenized plasmid pUC8 as the vector for assessment. Bacterial transformants exposed to a 50 Hz magnetic field showed lower percentages of white colonies than unexposed transformants. The lower white colony percentage indicated that DNA repair efficiency had improved. The improvement was mediated by induced overproduction of heat shock proteins DnaK/J (Hsp70/40).
Gos P, Eicher B, Kohli J, Heyer WD · 2000
Researchers exposed actively growing and resting yeast cells to 900 MHz fields at specific absorption rates of 0.13 and 1.3 W/kg. Assays measured forward mutation rates at CAN1, petite clone formation, intrachromosomal deletion formation, and intragenic recombination in the ADE2 gene. Fields were also tested in combination with the alkylating agent methyl methansulfonate to assess whether they could enhance genotoxic damage. Fluctuation tests failed to detect any significant effect on any of these measures, in the absence or presence of methyl methansulfonate.
Mineta M et al. · 1999
Researchers exposed Salmonella typhimurium tester strains to a 6.3 Tesla magnetic field with RF radiation for up to 60 minutes. They used TA98 and TA7001-7006 mixed strains to detect frameshift and point mutations. The rates of revertant mutation were not statistically significant in either strain.
Kol'tsov IuV, Korolev VN, Kusakin SA, · 1999
Researchers studied the effect of two-step exposure of bacterial objects to infrared laser and microwave pulse radiations. The effect depends on the time interval between two excitation steps and pulse duration. The biologically active dose of microwave radiation is much lower than that of infrared laser radiation, but laser radiation induces a stronger cellular response. Microwaves enhance the efficiency of infrared laser radiation.
Gos, P, Eicher, B, Kohli, J, Heyer, WD · 1997
Researchers exposed exponentially growing Saccharomyces cerevisiae cells to electromagnetic fields from 41.682 GHz to 41.710 GHz in 2 MHz increments at power densities of 0.5 and 50 microW/cm2. Cell division was assessed by time-lapse photography using two identical chambers that allowed concurrent control and exposure experiments. Control experiments showed the cells were dividing at submaximal rates, ensuring that any increase or decrease in division rate could be observed. No consistently significant differences were found between exposed and unexposed cells across multiple independent experiment series.
Belyaev IY, Shcheglov VS, Alipov YD, Polunin VA · 1996
Researchers studied how millimeter waves affected the genome conformational state of E. coli AB1157 cells across a frequency range of 51.64 to 51.85 GHz. The resonance frequency of 51.755 GHz did not shift with power density, though the magnitude of the effect differed significantly and depended on the power density of exposure. Sharp narrowing of the 51.755 GHz resonance at lower power densities was followed by an emergence of new resonance frequencies.
Kakita Y et al. · 1995
Researchers studied the effect of microwave irradiation on the survival of bacteriophage PL-1 specific for Lactobacillus casei using a commercial 2,450 MHz microwave oven. Phage inactivation followed almost first-order reaction kinetics and was unaffected by continuous versus intermittent irradiation or phage concentration but was affected by suspension volume which prevented heat loss. Phage genome DNA breakage was primarily caused by heat generated by microwave irradiation, while the same temperature from external heat did not affect phage DNA.
Unknown authors · 1994
Researchers exposed E. coli to weak, pulsed magnetic fields at 1.5 mT peak for 60 minutes. Quantitative two-dimensional gel electrophoresis showed numerous proteins both increased and decreased by a factor of two or more. Increases in the alpha subunit of DNA-dependent RNA polymerase and NusA were confirmed by Western blot analysis.
Unknown authors · 1993
Researchers exposed growing Escherichia coli strain AB1157 to a 1 Hz field at 1 or 3 kV/m and found no effect on spontaneous or UV-induced mutation frequencies to rifampicin resistance. Growth in the presence of charge did not alter the UV sensitivity of strains AB1157, TK702 umuC, or TK501 umuC uvrB. Although plasmid pKM101 increased UV resistance in repair-deficient strains, pre-growth in electric fields did not further increase UV resistance, and low frequency fields did not affect mitomycin C-induced mutation frequencies.
H.F. Huang, R.A. Yates · 1980
Researchers used a platen-electrode dielectric dryer at 85 MHz and 8.5 kW to prepuff extruded fungal mycelial fibers, then finish-dried the chunks in a 60°C hot-air oven for 16 hours. The extrudate shrank about 20% in length during radio-frequency heating with little further shrinkage during finish drying. Rehydration improved as initial free interstitial water was removed, with samples prepuffed to below 70% moisture rewetting well and softness increasing as moisture decreased. The method was found viable over frequencies from 27 MHz to 2450 MHz, with resilience and hydration controlled by the prepuffing termination moisture level.
