Initial yields of DNA double-strand breaks and DNA Fragmentation patterns depend on linear energy transfer in tobacco BY-2 protoplasts irradiated with helium, carbon and neon ions.
The ability of ion beams to kill or mutate plant cells is known to depend on the linear energy transfer (LET) of the ions, although the mechanism of damage is poorly understood. In this study, DNA double-strand breaks (DSBs) were quantified by a DNA fragment-size analysis in tobacco protoplasts irradiated with high-LET ions. Tobacco BY-2 protoplasts, as a model of single plant cells, were irradiated with helium, carbon and neon ions having different LETs and with gamma rays. After irradiation, DNA fragments were separated into sizes between 1600 and 6.6 kbp by pulsed-field gel electrophoresis. Information on DNA fragmentation was obtained by staining the gels with SYBR Green I. Initial DSB yields were found to depend on LET, and the highest relative biological effectiveness (about 1.6) was obtained at 124 and 241 keV/microm carbon ions. High-LET carbon and neon ions induced short DNA fragments more efficiently than gamma rays. These results partially explain the large biological effects caused by high-LET ions in plants.
Yokota
Yuichiro
Y
Gene Resource Research Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Takasaki, Gunma 370-1292, Japan. yokota.yuichiro@jaea.go.jp
Yamada
Shinya
S
Hase
Yoshihiro
Y
Shikazono
Naoya
N
Narumi
Issay
I
Tanaka
Atsushi
A
Inoue
Masayoshi
M
D000818:Animals; D002244:Carbon / Q000737:chemistry*; D002453:Cell Cycle; D004247:DNA / Q000737:chemistry* / Q000528:radiation effects*; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage; D053938:DNA Fragmentation; D004260:DNA Repair; D005720:Gamma Rays; D006371:Helium / Q000737:chemistry*; D007477:Ions; D009356:Neon / Q000737:chemistry*; D011523:Protoplasts / Q000528:radiation effects*; D013696:Temperature; D014026:Nicotiana / Q000235:genetics / Q000528:radiation effects*
D007477:Ions; D006371:Helium; D009356:Neon; D002244:Carbon; D004247:DNA