会議発表用資料 FISH analysis of chromosomal aberrations in mouse splenocytes following total body irradiation with heavy ions (iron-56 ions) and X-rays

勝部, 孝則  ,  王, 冰  ,  田中, 薫  ,  二宮, 康晴  ,  平川, 博一  ,  劉, 翠華  ,  丸山, 耕一  ,  Vares, Guillaume  ,  中島, 徹夫  ,  永松, 愛子  ,  藤森, 亮  ,  根井, 充

2017-10-18
内容記述
Purpose: High atomic number and energy (HZE) particles such as iron-56 (Fe) ions are a major contributor to health risks in long-term manned space exploration. To understand radiation-induced differential genotoxic effects between high linear energy transfer (LET) HZE particles and low LET photons, ground-based experiments were carried out at the National Institute of Radiological Sciences (NIRS) using total body irradiation (TBI) of mice with accelerated Fe particles generated by the Heavy Ion Medical Accelerator in Chiba (HIMAC). Materials and Methods: C57BL/6J Jms strain female mice of 8 weeks old were used in this study. Animals were treated in accordance with the Guidelines for the Care and Use of Laboratory Animals established by NIRS. TBI was performed at a dose ranging from 0.1 to 3.0 Gy for Fe particles (500 MeV/nucleon, 200 keV/m), or from 0.1 to 5.0 Gy for X-rays (200 kVp, 0.50 mm Al+0.50 mm Cu filter). At one or two months after TBI, splenocytes were isolated and cultured in the presence of mitogens for 24 h. Colcemid was added to the last 2 h of the culture. Metaphase chromosome spreads prepared from splenocytes were painted with the fluorescence in situ hybridization (FISH) probes for chromosomes 1 (green), 2 (red) and 3 (yellow). Chromosomal aberrations (CAs) visualized by FISH were classified as translocations, insertions, dicentrics, and acentric fragments. Results and Conclusions: The present study is still in progress and observation of CAs is ongoing. Induction of CAs was detected at 0.5 Gy and higher doses of both X-rays and Fe particles in cell samples obtained at one month after TBI. Unstable-type CAs (dicentrics and acentric fragments) were remarkably less frequent than stable-type ones (translocations and insertions) in every sample. When compared at same dose (3.0 Gy), stable-type CAs were found at 5-6 times lower frequency in mice exposed to Fe particles than in those exposed to X-rays. Probably because of its difficulty to repair, DNA damages induced by Fe particles might be removed frequently by cell death rather than be fixed as CAs. Funding: Ministry of Education, Culture, Sports, Science and Technology (MEXT) Grant-in-Aid for Scientific Research on Innovative Areas, Grant Number 15H05935 “Living in Space”.
63rd Annual International Meeting, Radiation Research Society

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