Long-term exposure to a pulsed magnetic field (1.5 mT, 25 Hz) increases genomic DNA spontaneous degradation

Abstract

The aim of this work is to investigate whether long-term pulsed magnetic field (MF) has genotoxic activity by induction of DNA damage on DNA molecules in vitro, in the absence of repair mechanisms. Yeast genomic DNA prepared by phenol extraction from S. cerevisiae cultures and the commercial DNA molecular weight marker Hyperladder I (HL-I) were exposed to 1.5 mT peak, pulsed 25 Hz MF, 8 h/day, 16 days. The total content of DNA (undamaged and damaged DNA) decreased during the exposure of genomic DNA to MF. On day 16 of exposure the DNA content was 41 ± 8.1%. In addition, the undamaged DNA decreases until 6.2 ± 3.1% for unexposed control samples and until 0.3 ± 0.1% for pulsed MF-treated samples at day 16 of exposure. Therefore, the pulsed MF induced at day 16 an increase of 20.7-fold more degradation of DNA molecules >10 000 bp (undamaged DNA) than that observed for unexposed control samples. However, no effect was observed for HL-I DNA marker exposures. We conclude that long-term exposure to a pulsed MF (1.5 mT peak, 25 Hz, 8 h/day, 16 days) induces an increment in the DNA spontaneous degradation of yeast genomic DNA.

• DNA damage
• DNA strand break
• genotoxicity
• genomic instability
• magnetic field

Acknowledgments

We express our gratitude to Dr A.A. Friedl (Strahlenbiologisches Institut der Universität München, Germany) for kindly providing the yeast strain. We also thank Ms. L. Gil Carmona (Universidad de Málaga, Spain) for her technical assistance and Dr. M. I. Prieto Barcia (Universidad de Málaga, Spain) for magnetic field measurements.