A Review on radiation tolerance mechanism of higher plants

Yokota, Yuichiro; Inoue, Masayoshi; Narumi, Issei; Funayama, Tomoo; Kobayashi, Yasuhiko; Tanaka, Atsushi

Hoshasen Seibutsu Kenkyu, 42(4), p.402 - 415, 2007/12

http://ci.nii.ac.jp/naid/40015788848

It has been known that many types of higher plants are several hundred times more radio-tolerant than mammals at an individual level. There was, however, no available information on the detail mechanism of radiation tolerance of higher plants. Thus, we have done the radiobiological studies using tobacco BY-2 cell line as a model plant cell. In their studies, we made clear that tobacco cells are ten times more radio-tolerant than mammalian cells, and that radioresistant tobacco cells can tolerate a large number of DNA double-strand breaks compared with mammalian cells. In this review, we discussed the radiation tolerant mechanism of higher plants by taking together the past findings with our latest data: tobacco cells are tolerant of radiation-induced chromosomal aberration although DNA double-strand break repair abilities of tobacco and mammalian cells are almost the same.

Introduction to plasma fusion energy

Takamura, Shuichi*; Kado, Shinichiro*; Fujii, Takashi*; Fujiyama, Hiroshi*; Takabe, Hideaki*; Adachi, Kazuo*; Morimiya, Osamu*; Fujimori, Naoji*; Watanabe, Takayuki*; Hayashi, Yasuaki*; et al.

Kara Zukai, Purazuma Enerugi No Subete, P. 164, 2007/03

no abstracts in English

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

Yokota, Yuichiro; Yamada, Shinya*; Hase, Yoshihiro; Shikazono, Naoya; Narumi, Issei; Tanaka, Atsushi; Inoue, Masayoshi*

Radiation Research, 167(1), p.94 - 101, 2007/01

https://doi.org/10.1667/RR0701.1

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.

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

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

Radiation Research, 163(5), p.520 - 525, 2005/05

https://doi.org/10.1667/RR3355

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.

A Study and Modeling about Ground Water Flow Considering the Properties of Sedimentary Soft Rock Summary Report

Inoue, Hiroyuki*; Ishiguro, Takeshi*; Kuji, Masayoshi*; Yoshino, Naoto

JNC TJ8400 2004-014, 59 Pages, 2004/02

JNC-TJ8400-2004-014.pdf:5.57MB

In this paper, authors examined the properties of sedimentary soft rock which might affect the groundwater flow rate and flow path in the sedimentary soft rock. As a general sample of sedimentary soft rock, we focused on the rock of HORONOBE area in HOKKAIDO prefecture. Then, following four issues were examined.1) a study of numerical flow rate analysis considering the difference of water density in the sedimentary soft rock.2) the hydro-geological modeling of HORONOBE area and a fundamental study of water pressure and saline density in HORONOBE area.3) a fundamental study of numerical coupling analysis about groundwater flow rate ,the difference of underground temperature, rock pressure and deformation. 4) a study about best performance of numerical flow rate analysis program.As a result, hydro-geological modeling of HORONOBE area using the information before 2002 as input data was succeeded by using the basic geological model which was made by IMAI et al,. And the applicability of TOUGH2 program as analysis method considering the density difference of underground water in sedimentary soft rock was verified. Then, we will be able to simulate underground flow considering the difference of saline density and specific water pressure in HORONOBE area. In addition, the applicability of TOUGH-FLAC program in which TOUGH2 was coupled with FLAC3D and consider rock pressure and deformation was verified. The best numerical performance of TOUGH2 program was studied in order to deal with large scale simulations. Then, it was shown that efficient method of the best numerical performance about TOUGH2 was possible.

LET dependence of lethality of carbon ion irradiation to single tobacco cells

Yokota, Yuichiro; Hase, Yoshihiro; Shikazono, Naoya; Tanaka, Atsushi; Inoue, Masayoshi*

International Journal of Radiation Biology, 79(8), p.681 - 685, 2003/08

https://doi.org/10.1080/09553000310001622832

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.

Reduction of survival and induction of chromosome aberrations in tobacco irradiated by carbon ions with different linear energy transfers

Hase, Yoshihiro; Yamaguchi, Muratoshi*; Inoue, Masayoshi*; Tanaka, Atsushi

International Journal of Radiation Biology, 78(9), p.799 - 806, 2002/09

https://doi.org/10.1080/09553000210152971

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.

Relationships among species revealed by the 5S rDNA spacer sequence and fluorescence in situ hybridization

Kitamura, Satoshi; Inoue, Masayoshi*; Shikazono, Naoya; Tanaka, Atsushi

Theoretical and Applied Genetics, 103(5), p.678 - 686, 2001/10

https://doi.org/10.1007/s001220100643

no abstracts in English

-resistance in the progeny of haploid mutants obtained by the culture of L. Anthers exposed to ion beams

Hamada, Kentaro*; Inoue, Masayoshi*; Tanaka, Atsushi; Watanabe, Hiroshi

Plant Biotechnology, 18(4), p.251 - 257, 2001/04

https://doi.org/10.5511/plantbiotechnology.18.251

no abstracts in English

Penetration controlled irradiation with ion beams for biological study

; Watanabe, Hiroshi; Shimizu, Takashi*; Inoue, Masayoshi*; Kikuchi, Masahiro; Kobayashi, Yasuhiko; Tano, Shigemitsu*

Nuclear Instruments and Methods in Physics Research B, 129(1), p.42 - 48, 1997/00

https://doi.org/10.1016/S0168-583X(97)00131-6

no abstracts in English