title: Effect of extremely low frequency magnetic field exposure on DNA transposition in relation to frequency, wave shape and exposure time.
abstract: OBJECTIVE
  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.
  
  
  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.
authors.affiliation: Department of Evolutionary Experimental Biology, University of Bologna, Bologna, Italy.
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Giorgi
authors.forename: Pamela
authors.initials: P
authors.lastname: Marcantonio
authors.forename: Ferdinando
authors.initials: F
authors.lastname: Bersani
authors.forename: Entelë
authors.initials: E
authors.lastname: Gavoçi
authors.forename: Brunella
authors.initials: B
authors.lastname: Del Re
mesh_terms: D004247:DNA / Q000235:genetics*; D004251:DNA Transposable Elements; D004307:Dose-Response Relationship, Radiation; D004574:Electromagnetic Fields; D004926:Escherichia coli / Q000378:metabolism; D005583:Fourier Analysis; D023281:Genomics; D007763:Lac Operon; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D013696:Temperature; D013997:Time Factors; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D004251:DNA Transposable Elements; D004247:DNA; D001616:beta-Galactosidase