The duration of exposure to 50 Hz magnetic fields: Influence on circadian genes and DNA damage responses in murine hematopoietic FDC-P1 cells

Mutat Res. 2021 Jul-Dec;823:111756. doi: 10.1016/j.mrfmmm.2021.111756. Epub 2021 Jun 12.


We investigated the effects of 50 Hz extremely low-frequency magnetic fields (MFs) on gene expression related to the circadian rhythm or DNA damage signaling and whether these fields modify DNA damage repair rate after bleomycin treatment. Murine FDC-P1 hematopoietic cells were exposed for different durations (15 min, 2 h, 12 h, and 24 h) to either 200 μT MFs or sham-exposures. Cells were then collected for comet assay or real-time PCR to determine immediate DNA damage level and circadian rhythm gene expression, respectively. To assess DNA-damage signaling and DNA repair rate, the cells were subsequently treated with 20 μg/mL bleomycin for 1 h and then either assayed immediately or allowed to repair their DNA for 1 or 2 h. We found that circadian rhythm-related genes were upregulated after 12 h of MF exposure and downregulated after 24 h of MF exposure, but none of the affected genes were core genes controlling the circadian rhythm. In addition, we found that the repair rate for bleomycin-induced damage was only decreased after MF exposure for 24 h. In conclusion, our findings suggest that the effects of MFs are duration-dependent; they were observed predominantly after long exposures.

Keywords: Circadian rhythm; DNA damage; DNA repair; Gene expression; Magnetic fields.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bleomycin / pharmacology
  • Cell Differentiation
  • Cell Line
  • Circadian Clocks / drug effects*
  • Circadian Clocks / genetics
  • Circadian Rhythm Signaling Peptides and Proteins / genetics*
  • Circadian Rhythm Signaling Peptides and Proteins / metabolism
  • Comet Assay
  • DNA Damage
  • DNA Repair*
  • Gene Expression / drug effects
  • Magnetic Fields / adverse effects*
  • Mice
  • Monocytes / cytology
  • Monocytes / drug effects*
  • Monocytes / metabolism
  • Mutagens / pharmacology
  • Mutation*
  • Myeloid Progenitor Cells / cytology
  • Myeloid Progenitor Cells / drug effects
  • Myeloid Progenitor Cells / metabolism
  • Time Factors


  • Circadian Rhythm Signaling Peptides and Proteins
  • Mutagens
  • Bleomycin