Radiation Protection Dosimetry Advance Access published online on December 13, 2006
Radiation Protection Dosimetry, doi:10.1093/rpd/ncl512
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Micros 2005 Special Issue
1 Department of Physics, Graduate School of Natural Sciences, International Christian University, 3-10-2, Osawa, Mitaka, Tokyo 181-8585, Japan
* To whom correspondence should be addressed.
Although the highest radiosensitivity of cells in the M phase among the other cell phases, such as the G1, S and G2 phases, has been known, the exact mechanism of radiosensitivity in mitotic cells remains unclear. Recently, mitotic arrest caused by DNA-damaging reagents has been shown, and the molecular mechanism in the arrest has been discussed in detail. In this study, abnormal cell-cycle progression in the M phase was investigated when a single mitotic cell in each mitotic stage was irradiated with a 5.35 keV X-ray microbeam focused on the cell nucleus. An X-ray microbeam irradiation system installed at BL-27 in Photon Factory, High Energy Accelerator Research Organization (HEARO, Tsukuba) was used. HeLa cells, genetically modified and expressing enhanced green fluorescent protein-tagged aurora kinase B, were used as irradiated samples in order to recognise the stage of each cell in the M phase. Thus, 10 Gy irradiation concentrated at the nucleus of a single cell elongated the cell-cycle progression in the M phase by delaying the metaphase/anaphase transition. The dose dependence of the elongation of the M phase was also examined. An irregular distribution of DNA in anaphase cells was observed after irradiation.
MITOTIC ARREST CAUSED BY AN X-RAY MICROBEAM IN A SINGLE CELL EXPRESSING EGFP-AURORA KINASE B
Y. Tanno 1, K. Kobayashi 2, M. Tatsuka 3, E. Gotoh 4, and K. Takakura 1 *
2 Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Oho 1-1, Tsukuba, Ibaraki 305-0801, Japan
3 Department of Molecular Radiobiology, Division of Genome Biology, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734, Japan
4 Department of Virology I, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162, Japan
K. Takakura, E-mail: kaoru{at}icu.ac.jp
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