この研究は、仔ウシ胸腺の腫瘍由来循環DNA（ctDNA）を用いた実験で、携帯電話からの無線周波電磁界（RF-EMF；940 MHz、電界強度15 V / m、SAR = 40 mW / kg、ばく露時間45分間）のばく露がDNA構造に与える影響をばく露直後および2時間後に、さまざまな分光分析機器を用いて評価した。その結果、紫外・可視領域を利用する円偏光二色性（CD）分析では、携帯電話のRF-EMFはctDNA構造に著しい障害を引き起こすかもしれないことが示された；ばく露直後および2時間後のばく露群のDNA溶液は、無ばく露群のDNA溶液に比べ、温度が相対的に不安定であった；ばく露群のDNA試料は、無ばく露群のDNA試料に比べ、蛍光発光が高かった；これは、ばく露を受けたDNA構造の拡大が原因で生じた可能性がある；動的光散乱法（DLS）およびゼータ電位測定により、RF-EMFがDNAの表面電荷およびサイズの増加をもたらすことが示された；ただし、ばく露直後のDNAの構造は、2時間後のものと有意な差はなかったので、RF-EMFにより誘発される立体配座の変化は不可逆的である、と報告している。
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To evaluate the possible biological effects of mobile phone exposure on the structure of calf thymus DNA immediately and 2 hours after 45 minutes exposure.
All data are obtained from the means of respectively three independent measurements.
|ばく露時間||continuous for 45 minutes|
|ばく露装置の詳細||exposure system consisted of a 17 cm x 17 cm square aluminium waveguide with a length of 60 cm; waveguide was split in its center in two equal parts to provide access to the X-shaped sample holder; two fans at two sides of the waveguide circulated the air and kept the temperature approximately constant in the incubator (37°C); the DNA sample in a polystyrene tube (with 5 cm in length and 1 cm in diameter) was fixed horizontally inside the X-shape holder and placed inside the waveguide|
|Additional information||control sample was placed in a small shielded box and placed outside the waveguide structure, but in an incubator to have the same temperature treatment|
The UV-vis and circular dichroism experiments showed that the exposure caused disturbances on the structure of DNA (absorbance in the UV-vis spectrum was incremented and a shift in the maximum of the circular dichroism spectrum, as well as a decrease of the molar ellipticity in exposed DNA). In addition the exposed DNA samples were thermally more unstable than unexposed DNA (melting point decreased in exposed samples). Furthermore, the exposed DNA samples showed an increased fluorescence emission compared to the unexposed DNA samples, which may have occurred attributable to expansion of the exposed DNA (increased fluorescence intensity in exposed DNA incubated with berberine). The results of dynamic light scattering and zeta potential experiments demonstrated that the surface charge and the size of DNA was incremented in exposed samples compared to unexposed ones (hydrodynamic radius and zeta potential increased in exposed samples). The structure of the DNA examined immediately after the exposure is not significantly different from the DNA examined 2 h after the exposure.
Collectively, these experiments indicate that exposure to an electromagnetic radiofrequency field can alter the structure of DNA irreversibly.