Study type: Medical/biological study (experimental study)

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

Published in: Int J Radiat Biol 2011; 87 (6): 601-608

Aim of study (acc. to author)

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

Background/further details

Two different bacterial Escherichia coli strains were used.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 20–75 Hz
Exposure duration: continuous for 15 min or 90 min
Exposure 2: 20–75 Hz
Modulation type: pulsed
Exposure duration: continuous for 15 min or 90 min

Exposure 1

Main characteristics
Frequency 20–75 Hz
Type
Waveform
Exposure duration continuous for 15 min or 90 min
Additional info 20, 50, 75 Hz
Exposure setup
Exposure source
Setup two pairs of double-wrapped Helmholtz coills with a diameter of 23 cm and 40 (20 + 20) turns, placed in an incubator with a constant temperature of 37° C; 10 cm high cylindrical exposure area with a diameter of 12 cm and a field homogeneity of 5% in the center of the coil system; samples placed in Petri dishes with 9 cm diameter in the center of the coil system where the field uniformity was within 1%
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT effective value measured - -
cf. remarks - - - - dB/dt = 0.66 T/s

Exposure 2

Main characteristics
Frequency 20–75 Hz
Type
Exposure duration continuous for 15 min or 90 min
Additional info 20, 50, 75 Hz
Modulation
Modulation type pulsed
Rise time 1 ms
Duty cycle 50 %
Pulse type rectangular
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT effective value measured - -
cf. remarks - - - - dB/dt = 0.14 T/s

Reference articles

  • Del Re B et al. (2006): Synthesis of DnaK and GroEL in Escherichia coli cells exposed to different magnetic field signals.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

Both Tn10 and Tn5 transpositions decreased under sinusoidal magnetic field and increased under pulsed square wave magnetic field, as compared to sham exposure. No significant difference was found between frequencies and between exposure times.
In conclusion, extremely low frequency magnetic field exposure affects transposition activity and the effects depended on the wave shape of the field, but not on the frequency and the exposure time, at least in the range observed.

Study character:

Study funded by

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