Effect of 2.45 mT sinusoidal 50 Hz magnetic field on Saccharomyces cerevisiae strains deficient in DNA strand breaks repair

Abstract

Purpose: To investigate whether extremely-low frequency magnetic field (MF) exposure produce alterations in the growth, cell cycle, survival and DNA damage of wild type (wt) and mutant yeast strains.

Materials and methods: wt and high affinity DNA binding factor 1 (hdf1), radiation sensitive 52 (rad52), rad52 hdf1 mutant Saccharomyces cerevisiae strains were exposed to 2.45 mT, sinusoidal 50 Hz MF for 96 h. MF was generated by a pair of Helmholtz coils. During this time the growth was monitored by measuring the optical density at 600 nm and cell cycle evolution were analysed by microscopic morphological analysis. Then, yeast survival was assayed by the drop test and DNA was extracted and electrophoresed.

Results: A significant increase in the growth was observed for rad52 strain (P = 0.005, Analysis of Variance [ANOVA]) and close to significance for rad52 hdf1 strain (P = 0.069, ANOVA). In addition, the surviving fraction values obtained for MF-exposed samples were in all cases less than for the controls, being the P value obtained for the whole set of MF-treated strains close to significance (P = 0.066, Student's t-test). In contrast, the cell cycle evolution and the DNA pattern obtained for wt and the mutant strains were not altered after exposure to MF.

Conclusions: The data presented in the current report show that the applied MF (2.45 mT, sinusoidal 50 Hz, 96 h) induces alterations in the growth and survival of S. cerevisiae strains deficient in DNA strand breaks repair. In contrast, the MF treatment does not induce alterations in the cell cycle and does not cause DNA damage.

Keywords:

• Low frequency magnetic fields
• yeast growth
• yeast cell cycle
• survival
• DNA damage
• genotoxicity

Acknowledgements

We express our gratitude to Dr A.A. Friedl (Strahlenbiologisches Institut der Universität München, Germany) for kindly providing the yeast strains. We also thank Ms L. Gil Carmona (Universidad de Málaga, Spain) for her technical assistance, Dr M. I. Prieto Barcia (Universidad de Málaga, Spain) for magnetic field measurements, Dr F. Rius Díaz (Universidad de Málaga, Spain) for her assistance with Statistics and Dr D. P. Godden for his assistance with the English composition of this paper. This work has been supported by the “Plan Andaluz de Investigación, Desarrollo e Innovación (PAIDI); Junta de Andalucía”, code CTS-181.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.