研究のタイプ: 医学/生物学の研究 (experimental study)

[ELF変動磁界はDNA損傷誘導によって生殖を低下させる] med./bio.

ELF Alternating Magnetic Field Decreases Reproduction by DNA Damage Induction.

掲載誌: Cell Biochem Biophys 2013; 67 (2): 703-716

この研究は、キイロショウジョウバエ生殖に対する50 Hz磁界磁界強度1、11、21G:各群とも雌雄10匹の計20匹)の影響を調べた。羽化した時点から5日間連続してばく露した。生殖力はF1蛹(よく定義されたプロトコルで判定)の数で評価した。その結果、磁界により最大4.3%生殖が低下した;磁界強度の増加に伴って影響は強くなった;生殖力の低下は、重大なDNA損傷(DNA断片化)およびその結果としての細胞死誘導によるものであった;DNA損傷(最大7.5 %)の方が生殖力低下よりも顕著であった;TUNEL分析により、卵形成進行の初期、中期のそれぞれ特定の1段階で特に反応性高いDNA断片化が観察された(以前の著者らのマイクロばく露研究では、DNA断片化は初期から中期の全ての段階で誘導されたのとは対照的であるとしている)、などを報告している。

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研究目的(著者による)

To study the effect of extremely low frequency magnetic fields on the reproduction of the fly Drosophila melanogaster.

詳細情報

Newly eclosed insects were separated into 12 identical groups of ten males and ten females and exposed (at 3 different intensities) or sham exposed continuously during the first 5 days of their adult lives. For the first 48 hours male and female flies were put in different glass vials. After the 48 h, when both males and females of each group were sexually mature, they were put together (10 pairs) in another glass vial and they were allowed to mate and lay eggs for the next 72 h. After these 5 days, the flies were removed from the vials. The female flies were dissected and ovaries studied for DNA damage. The vials with the developing embryos were incubated in the culture room for 6 additional days without exposure.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 50 Hz
ばく露時間: continuous for 5 days
  • 磁束密度: 2.1 mT (in the centre of the air core)
  • 電界強度: 2.72 V/m (induced electric field (remark EMF-Portal: seems to be the induced eddy current in the fly?))
  • electric current in the coil = 1.48 A
ばく露2: 50 Hz
ばく露時間: continuous for 5 days
  • 磁束密度: 1.1 mT (in the centre of the air core)
  • 電界強度: 1.43 V/m (induced electric field (remark EMF-Portal: seems to be the induced eddy current in the fly?))
  • electric current in the coil = 0.77 A
ばく露3: 50 Hz
ばく露時間: continuous for 5 days
  • 磁束密度: 0.1 mT (in the centre of the air core)
  • 電界強度: 0.13 V/m (induced electric field (remark EMF-Portal: seems to be the induced eddy current in the fly?))
  • electric current in the coil = 0.07 A

ばく露1

主たる特性
周波数 50 Hz
タイプ
  • magnetic field
波形
  • sinusoidal
ばく露時間 continuous for 5 days
ばく露装置
ばく露の発生源/構造
チャンバの詳細 glass tubes with flys were put in the centre of the air cores of the coils, suspended by nylon strings
ばく露装置の詳細 two nearly identical cylindrical coils were used; both coils had a length of 0.25 m, a radius of 7.5 x 10-2 m and a diameter of insulated wire of 2 x 10-3 m; number of turns in each coil = 330; in the first coil, the turns were parallel and in the same direction, thus generating a magnetic field; in the second coil, half of the turns were antiparallel (parallel but in opposite direction), so that the magnetic field (and the magnetically induced electric field) in a region of about 12 cm width around the centre of the coil was zero (used for sham exposure)
Sham exposure A sham exposure was conducted.
Additional information after it was checked by preliminary experiments that the sequence (mutual position) of the two coils did not affect the outcome of the experiments, their positions were always the same during all experiments, at a certain place of the laboratory with the minimum stray 50-Hz fields and in at least 2 m distance between each other so that the fields of the "exposure coil" did not affect the "sham exposure coil"
パラメータ
測定量 種別 Method Mass 備考
磁束密度 2.1 mT - 測定値および計算値 - in the centre of the air core
電界強度 2.72 V/m - 計算値 - induced electric field (remark EMF-Portal: seems to be the induced eddy current in the fly?)
参照 - - - - electric current in the coil = 1.48 A

ばく露2

主たる特性
周波数 50 Hz
タイプ
  • magnetic field
波形
  • sinusoidal
ばく露時間 continuous for 5 days
ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
磁束密度 1.1 mT - 測定値および計算値 - in the centre of the air core
電界強度 1.43 V/m - 計算値 - induced electric field (remark EMF-Portal: seems to be the induced eddy current in the fly?)
参照 - - - - electric current in the coil = 0.77 A

ばく露3

主たる特性
周波数 50 Hz
タイプ
  • magnetic field
波形
  • sinusoidal
ばく露時間 continuous for 5 days
ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
磁束密度 0.1 mT - 測定値および計算値 - in the centre of the air core
電界強度 0.13 V/m - 計算値 - induced electric field (remark EMF-Portal: seems to be the induced eddy current in the fly?)
参照 - - - - electric current in the coil = 0.07 A

ばく露を受けた生物:

方法 影響評価項目/測定パラメータ/方法

研究対象とした生物試料:
研究対象とした臓器系:
調査の時期:
  • ばく露後

研究の主なアウトカム(著者による)

In the exposed groups, the number of F1 pupae was decreased in comparison to the sham exposed group. The stronger the field intensity the less pupae were counted. However, this effects was only statistically significant with magnetic flux densities of 1.1 and 2.1 mT.
In the ovaries, DNA fragmentation due to apoptotic cell death was found in all exposure groups, but not in the sham exposure group. This effect increased and became more statistically significant with higher field intensities.
The authors conclude that exposure to a 50 Hz-magnetic field could decrease insect reproduction by DNA damage.

研究の種別:

研究助成

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