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Comparative radiation tolerance based on the induction of DNA double-strand breaks in Tobacco BY-2 cells and CHO-K1 cells irradiated with $$gamma$$ rays

$$gamma$$線照射したタバコBY-2細胞及びチャイニーズハムスターCHO-K1細胞におけるDNA2本鎖切断生成に基づく放射線耐性の比較

横田 裕一郎; 鹿園 直哉; 田中 淳; 長谷 純宏; 舟山 知夫; 和田 成一; 井上 雅好*

Yokota, Yuichiro; Shikazono, Naoya; Tanaka, Atsushi; Hase, Yoshihiro; Funayama, Tomoo; Wada, Seiichi; Inoue, Masayoshi*

一般的に高等植物は哺乳動物よりも放射線に強い。高等植物の放射線耐性機構を探索するために、タバコBY-2細胞及びその対照としてチャイニーズハムスターCHO-K1細胞に$$gamma$$線を照射し、パルスフィールドゲル電気泳動法によりDNA2本鎖切断(DSB)を定量した。タバコBY-2細胞におけるDSB生成量(2.0$$pm$$0.1DSBs Gbp$$^{-1}$$Gy$$^{-1}$$)はCHO-K1細胞のわずか1/3であり、一方で、平均致死線量の$$gamma$$線照射による細胞あたりのDSB生成量は、タバコBY-2細胞(263.2$$pm$$13.2)ではCHO-K1細胞より5倍多かった。これらの結果は、タバコBY-2細胞で認められた放射線耐性の原因として、DNA損傷が少ないばかりでなく、DNA損傷が効果的に修復されることを示唆している。

Higher plants are generally more tolerant to ionizing radiation than mammals. To explore the radiation tolerance of higher plants, the amount of DNA double-strand breaks (DSBs) induced by $$gamma$$-rays was investigated in tobacco BY-2 cells and compared with that investigated in Chinese hamster ovary (CHO)-K1 cells as a reference. The resulting DNA fragments were separated by pulsed-field gel electrophoresis and stained with SYBR Green I. Initial DSB yield was then quantified from the fraction of DNA fragments shorter than 1.6 Mbp based on the assumption of random distribution of DSBs. The DSB yield in tobacco BY-2 cells (2.0 $$pm$$ 0.1 DSBs Gbp$$^{-1}$$ Gy$$^{-1}$$) was only one-third of that in CHO-K1 cells. Furthermore, the calculated number of DSBs per diploid cell irradiated with $$gamma$$-rays of mean lethal dose was five times greater in tobacco BY-2 cells (263.2 $$pm$$ 13.2) than in CHO-K1 cells. These results suggest that the radiation tolerance of tobacco BY-2 cells appears to be due to not only a lower induction of DNA damage but also a more efficient repair of the induced DNA damage.

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パーセンタイル:48.92

分野:Biology

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