Changes in the secondary structure of DNA under the influence of external low-intensity electromagnetic field

Semin IuA, Shvartsburg LK, Dubovik BV

Radiats Biol Radioecol 35(1):36-41, 1995

[Article in Russian]

The effect of weak RF on the stability of DNA secondary structure was studied in vitro. DNA was exposed in the presence of glycine and formaldehyde.

Aminomethynol compounds, which form in this medium, react with DNA bases at single-strand sites, which prevents recovery from damage to the DNA secondary structure. The damage accumulates during the incubation, and its amount can be estimated from the dynamics of thermal DNA denaturalization after RF or sham exposure.

Samples were exposed in an anechoic chamber at 18oC at 10 different microwave frequencies simultaneously (4- to 8 GHz, 25 ms pulses, 0.4 to 0.7 mW/cm² peak power, 1- to 6-Hz repetition rate, no heating). Parallel control samples were sham exposed in a shielded area in the same chamber.

The experiments established that irradiation at 3 or 4 Hz and 0.6 mW/cm² peak power clearly increased the accumulated damage to the DNA secondary structure (P< .00001). However, changing the pulse repetition rate to 1, 5, 6 Hz, as well as changing the peak power to 0.4 or 0.7 mW/cm², eliminated the effect entirely.

Thus, the effect occurred only within narrow Świndowsą of the peak intensities and modulation frequencies.