Experimental Investigation Of DNA Radiation Damage Induced By Heavy Ions

Research on biological damages caused by various ionizing radiations is the frontier area of radiobiology and radiology. It is also the hot spot included in recent public focus. This research has closed relationship with a wide range of cross-science areas, such as basic research on cancer therapy by heavy ion radiation method, radiation danger level evaluation in space and biological damage induced by long term, low-level dose radiation environment, etc.DNA is the carrier of biological information and the main target of biological effects induced by ionizing radiations. This process, from the beginning of radiation to the following bio-effects, is very complicated. The damage of DNA is the most basic and important sector in this process. Meanwhile, the double strand breaks (DSB) of DNA molecule is the primary damage of all biological effectiveness induced by ionizing radiation. The study of the physics mechanism of the DSB on DNA molecules in the early period of ionizing radiation is very important.7Li(Z=3, LET=120keV/jam, E=26MeV) and 12C(Z=6, LET=260keV/|am, E=84MeV) ion beams were produced by HI-13 tandem accelerator at Department of Nuclear Physics, China Institute of Atomic Energy. Helium particleO particle)(z=2, LET=90keV/|am, E=5.48MeV) was produced by 241Am decay. The purified plasmid DNA was irradiated with the dose ranged from l.OGy to lO.OGy. Using the advanced atomic force microscopy (AFM) and molecularbiological technology------electrophoresis technology, the DNA samples wereobserved experimentally and resulted in the follows:1. By means of the AFM made in Shanghai AiJian Co., Ltd. And Digital Instruments Co., Ltd (U.S.), the DNA strand and their fragments were observed successfully.2. By comparison with AFM experiments of three categories of ion beams, the result has been observed in qualitatively: in the uniform dose, the higher LET heavy ions have caused more double strand breaks than the lower LET radiation.3. DNA double strand breaks (DSBs) induced by ion beams of gel electrophoresis experiment has shown positive linear with dose, i.e., double strand breaks will increase as the dose increased.In conclusion, comparing with low LET radiation, the higher LET heavy- ion radiation to purified plasmid DNA has more efficient biological effectiveness.