Bystander effects induced with inner shell ionization followed by Auger effects

在大多数受辐射的细胞可以存活的低剂量区域，现在已知对辐射的生物反应是细胞内和/或细胞间信号通路的结果。本研究项目的目的是从能量的角度研究辐射沉积能量引起的原始信号的爆发。为了充分利用本课题组在云雾科学研究(A)项目中开发的微束细胞辐照系统中同步辐射X射线的稳定性，我们研制了一种能量可调谐的微束X射线辐照系统。在克服了有关细胞照射室的一些问题后，我们成功地获得了可靠和可重复性的生物学结果。虽然由于波束时间不足，这些结果仍然是初步的，但结果总结如下1.结果：1.当用调谐到Fe K壳层吸收边的X射线照射时，掺铁细胞的旁观者细胞死亡率低于边缘以下能量X射线照射的细胞。当用调到S K边吸收边的软X射线照射时，受照射的细胞表现出比低于边缘的X射线照射更低的敏感性。对于旁观者细胞死亡，S K边X射线表现出比边缘下X射线更高的致命性，我们将继续研究导致上述有趣生物现象的机制。

In low dose region where most of the irradiated cells can survive, biological response to radiation is now known to appear as a result of intra-and/or inter-cell signaling pathway. Purpose of this research project is to investigate the outbreak of original signal induced with energy deposited by radiation from energetic point of view. In order to utilize the tenability of synchrotron X-rays in the microbeain cell irradiation system which had been developed in our previous project funded by scientific research (A) of MIST, we developed an energy-tunable microbeam X-ray irradiation system by aligning all the components along the horizontal beam axis. After overcoming some problems concerning cell irradiation chamber, we succeeded in getting reliable and reproducible biological results. Although these are still preliminary due to the shortage of the beamtime, results are summarized as follows.1. When irradiated with X-rays tuned to Fe K-shell absorption edge, Fe-incorporated cells showed lower bystander cell death than irradiated with below-edge energy X-rays.2. When irradiated with soft X-rays tuned to S K-edge absorption edge, irradiated cells showed less sensitive than cells irradiated with below-edge X-rays. As for the bystander cell death, S K-edge X-rays showed higher lethality than below-edge X-rays.We will continue to study the mechanisms leading to interesting biological phenomena obtained as above.