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values calculated from radiocesium interception potentialUno, Koichiro*; Nakao, Atsushi*; Okumura, Masahiko; Yamaguchi, Akiko; Kogure, Toshihiro*; Yanai, Junta*
Nihon Dojo Hiryo Gaku Zasshi, 94(5), p.376 - 384, 2023/10
Radiocesium interception potential (RIP) has been widely used as a quantitative indicator of cesium (Cs) adsorption capacity of soil, but it has been found that RIP does not always correlate with the distribution coefficient () of Cs in the actual environment. In order to clarify the cause of this discrepancy, we measured Kd using more realistic solutions, compared it with RIP, and evaluated the mineral structure. As a result, it was found that the concentration of competing cations, such as potassium and ammonium ions, and the structural change of the mineral itself are important.
Yamaguchi, Akiko; Asano, Ikumi*; Kitagawa, Yuri*; Meng, C.*; Nakao, Atsushi*; Okumura, Masahiko
Proceedings of Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo 2020 (SNA + MC 2020), p.127 - 130, 2020/10
no abstracts in English
/M phase after 
-ray irradiationYokota, Yuichiro; Funayama, Tomoo; Wada, Seiichi*; Hase, Yoshihiro; Kobayashi, Yasuhiko; Inoue, Masayoshi*; Tanaka, Atsushi; Narumi, Issei
JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 69, 2008/03
no abstracts in English
Yokota, Yuichiro; Yamada, Shinya*; Hase, Yoshihiro; Shikazono, Naoya; Narumi, Issei; Tanaka, Atsushi; Inoue, Masayoshi
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 77, 2007/02
no abstracts in English
Yokota, Yuichiro; Yamada, Shinya*; Hase, Yoshihiro; Shikazono, Naoya; Narumi, Issei; Tanaka, Atsushi; Inoue, Masayoshi*
Radiation Research, 167(1), p.94 - 101, 2007/01
Times Cited Count：27 Percentile：61.29(Biology)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 is poorly understood. In this study, tobacco BY-2 protoplasts as a model of single plant cells were irradiated with helium, carbon and neon ions having different LETs. Following irradiation, DNA fragments were separated into sizes by pulsed-field gel electrophoresis. Information on DNA fragmentation was obtained by staining the gels with SYBR Green I. Initial DSB yields (Gbp
Gy) were found to depend on LET, and the highest relative biological effectiveness (about 1.6) was obtained at 124 and 241 keV/
m carbon ions. High-LET carbon and neon ions yielded short DNA fragments more efficiently than rays. These results partially explain the large biological effects caused by high-LET ions in plants.
species with different ploidy levels revealed by 5S rDNA spacer sequences and FISH/GISHKitamura, Satoshi; Tanaka, Atsushi; Inoue, Masayoshi*
Genes and Genetic Systems, 80(4), p.251 - 260, 2005/08
Times Cited Count：10 Percentile：20.11(Biochemistry & Molecular Biology)We used the intergenic spacer sequences of the 5S ribosomal RNA genes (5S rDNA) to obtain insights into the genomic origin of putative amphidiploid/tetraploid species with 2n=48 and their descendants in Nicotiana. Comparison of the spacer sequences with those from diploid (2n=24) Nicotiana species made it possible to detect some groups consisting of the sequences from the 2n=24 and 2n=48 level species. Chromosomal localizations of the 5S rDNA arrays were similar in most groups. The relationships suggested by the 5S rDNA were also assessed at the genome level by using genomic in situ hybridization. We showed that the grouping based on the 5S rDNA spacer sequence reflects high genomic homology between 2n=24 and 2n=48 level species. Our results are generally in agreement with the relationships previously suggested by morphological and cytogenetic observations, and some novel relationships were also revealed.
raysYokota, Yuichiro; Shikazono, Naoya; Tanaka, Atsushi; Hase, Yoshihiro; Funayama, Tomoo; Wada, Seiichi; Inoue, Masayoshi*
Radiation Research, 163(5), p.520 - 525, 2005/05
Times Cited Count：20 Percentile：48.84(Biology)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 -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 
0.1 DSBs Gbp Gy) was only one-third of that in CHO-K1 cells. Furthermore, the calculated number of DSBs per diploid cell irradiated with -rays of mean lethal dose was five times greater in tobacco BY-2 cells (263.2 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.
Yokota, Yuichiro; Hase, Yoshihiro; Shikazono, Naoya; Tanaka, Atsushi; Inoue, Masayoshi*
International Journal of Radiation Biology, 79(8), p.681 - 685, 2003/08
Times Cited Count：21 Percentile：78.49(Biology)To determine the radiation sensitivity and the relationship between linear energy transfer (LET) and relative biological effectiveness (RBE) in single plant cells irradiated with heavy ions, single tobacco (BY-2) cells were irradiated with carbon ions (78.6 to 309 kev/m) and gamma rays (0.2 kev/m). Two weeks after the irradiation, colonies derived from the irradiated cells that had 16 cells or more were counted as survivors. The surviving fraction was fitted using the single-hit, multitarget theory. The dose needed to reduce the surviving fraction of the cells to 0.1 (D
) of gamma rays and carbon ions were 47.2 and 10.5 to 12.6 Gy, respectively. The radiation sensitivity of single tobacco cells was much lower than that of mammalian cells, although the mean number of base pairs per chromosome in the two cell types is similar. The RBE based on the D peaked at a LET of 247 keV/m. The RBE peak based on the D of carbon ions in single tobacco cells occurred at a higher LET than it dose in other organisms.
Domin and 
L., obtained by crossing with pollen exposed to helium ion beams or -raysKitamura, Satoshi; Inoue, Masayoshi*; Omido, Nobuko*; Fukui, Kiichi*; Tanaka, Atsushi
Nuclear Instruments and Methods in Physics Research B, 206, p.548 - 552, 2003/05
Times Cited Count：8 Percentile：50.24(Instruments & Instrumentation)no abstracts in English
Hase, Yoshihiro; Yamaguchi, Muratoshi*; Inoue, Masayoshi*; Tanaka, Atsushi
International Journal of Radiation Biology, 78(9), p.799 - 806, 2002/09
Times Cited Count：35 Percentile：88.28(Biology)In order to determine the relationship between linear energy transfer (LET) and relative biological effectiveness (RBE) for survival reduction and chromosome aberration induction in plants, tobacco seeds were exposed to carbon ions having LET ranging from 92 to 260 keV/m. The RBE for both endpoints increased with increasing LET and showed the highest value at 230 keV/m. The highest RBE was 65.0 for survival reduction and 52.5 for chromosome aberration induction. The types and yield ratio of chromosome aberrations such as fragments and bridges were not affected by the radiation type at 0.5 mm root length (immediately after radicle emergence). As the rots elongated, the frequency of aberrant cells gradually decreased. The number of cells with fragments decreased faster than the number of cells with bridges. The decrement of chromosome aberrations appear to be slower in roots irradiated by carbon ions than in roots irradiated by -rays. These results show a close relationship between survival reduction and chromosome aberration induction in plants.
-resistance in the progeny of haploid mutants obtained by the culture of 
L. Anthers exposed to ion beamsHamada, Kentaro*; Inoue, Masayoshi*; Tanaka, Atsushi; Watanabe, Hiroshi
Plant Biotechnology, 18(4), p.251 - 257, 2001/04
no abstracts in English
Yokota, Yuichiro; Wada, Seiichi*; Shikazono, Naoya; Hase, Yoshihiro; Inoue, Masayoshi*; Tanaka, Atsushi; Narumi, Issei
no journal, ,
no abstracts in English
Yokota, Yuichiro; Yamada, Shinya*; Hase, Yoshihiro; Shikazono, Naoya; Narumi, Issei; Tanaka, Atsushi; Inoue, Masayoshi*
no journal, ,
The ability of ion beams to kill or mutate plant cells is known to depend on LET of the ions, although the mechanism of damage is poorly understood. In this study, tobacco BY-2 protoplasts, as a model of single plant cells, were irradiated by helium, carbon and neon ions with different LETs at ice temperature. Resulting DNA fragments were separated into sizes by pulsed-field gel electrophoresis. Initial DSB yields and intervals between neighboring DSBs were evaluated from the DNA fragmentation patterns. Initial DSB yields (Gbp DNA Gy) were found to depend on LET, and the highest value was obtained at 124 and 241 keV/m carbon ions in the investigated range. High-LET carbon and neon ions induced DSBs at closer sites than rays did. These results partially explained the large biological effects caused by high-LET heavy ions in plants.
Yokota, Yuichiro
no journal, ,
no abstracts in English
Yokota, Yuichiro; Hase, Yoshihiro; Funayama, Tomoo; Kobayashi, Yasuhiko; Tanaka, Atsushi; Narumi, Issei; Wada, Seiichi*; Inoue, Masayoshi*
no journal, ,
no abstracts in English
Uno, Koichiro*; Nakao, Atsushi*; Okumura, Masahiko; Kogure, Toshihiro*; Yamaguchi, Akiko; Takeda, Hikaru*; Maruyama, Hayato*; Shinano, Takuro*; Yanai, Junta*
no journal, ,
Biotite inhibits radiocesium (RCs) transfer from soil to plants by two functions of selective adsorption of radiocesium (Cs) between layers (Cs adsorption ability) and K supply from between layers (K supply ability). However, it was difficult to distinguish between the two. In this study, the authors succeeded in preparing biotite in which both functions are variously different by preparing weathered biotite in which interlayer pottasium (K) was replaced with rubidium (Rb) to lose K supply ability. By systematically comparing these biotites, the authors clarified the effects of Cs adsorption ability and K supply ability on Cs transfer to plants.
