Abstract
Recently radiation biology using microbeam is developing in the world. In this study, abnormal cell division in cultured human cells induced by X ray microbeam is investigated using synchrotron radiation as a microbeam radiation source. Irradiation with microbeam X rays on each cell enabled us to analyze the cell division in M phase minutely and in detail.
HeLa cells with EGFP Aurora B protein were used all through this study. The EGFP Aurora B protein can indicate the each stage in M phase of each cell. The irradiation was carried out at Beamline–B27 of PF in KEK. The energy of the beam was 5.35 keV, and the beam size was 10 µm square. The irradiation dose rate was about 20 Gy per min. Each cell was irradiated with 10 Gy X rays at various stages in M phase. The cells under fluorescent microscope were set at 35±1 °C using special heating system. Thus the cell cycle progress could be normally observed and progress of irradiated cell also could be observed easily.
Results was that 10 Gy irradiation to cells before metaphase induced the cell cycle arrest at metaphase. The elapsed time of each stage except for metaphase was not significantly different from unirradiatted HeLa cells. Cells irradiated after anaphase progressed their cycle at normal speed. From these results, it is suggested that the existence of mechanism to arrest the cell cycle at metaphase caused by irradiation of X rays. Now, we are researching about mad2 to evaluate the relation between mechanism of metaphase arrest and spindle assembly checkpoint.
