Abstract
We have developed an X-ray microbeam irradiation system using synchrotron radiation, by which we can recognize cells individually and irradiate one by one with desired dose of monochromatic X-rays. Human fibroblast cells (NB1-RGB) were individually irradiated with X-ray microbeam, and fixed and stained by γ-H2AX antibody. The slit system installed just below the sample stage enables to change the size of the beam easily and the minimum size is 5 micrometer square. We irradiated the cells with two different microbeam in sizes, 5 and 10 micrometer square.
All the irradiated cells could be found at the revisited position, and could be distinguished from surrounding unirradiated cells by their high yield of fluorescence of γ-H2AX. Most fluorescent foci were observed in localized area in cell nuclei, the sizes of which were almost the same as the beam size. Difference in size of the stained area can be easily recognized between cells irradiated with 5-micrometer beam and those irradiated with 10-micrometer beam. Dose dependence of γ-H2AX induction was also clearly observed.
