低能离子束对微生物细胞的刻蚀与损伤研究  

Studies on Etching and Damage Action of Low Energy Ion Beam on Microbial Cells

作　　者：宋道军[1] 余汛[1] 姚建铭[1] 邵春林[1] 

机构地区：[1]中国科学院等离子体物理研究所离子束生物工程中心

出　　处：《生物化学与生物物理学报》1998年第6期570-574,共5页

基　　金：国家自然科学基金

摘　　要：以耐辐射异常微球菌（Ｄｅｉｎｏｃｏｃｃｕｓｒａｄｉｏｄｕｒａｎｓ）和大肠杆菌（Ｅ．ｃｏｌｉ）为试材，用显微扫描电镜（ＳＥＭ）和电子自旋共振（ＥＳＲ）波谱仪研究了２０ｋｅＶ的Ｎ＋离子注入对其细胞的作用。结果表明，Ｎ＋离子注入对两种微生物既存在着直接作用的刻蚀损伤又存在着能量沉积所产生自由基的间接作用；对细胞的直接刻蚀作用是导致ＤＮＡ损伤和生物诱变的主要原因，而自由基所引起的主要是ＤＮＡ以外生物大分子的损伤和细胞的膜脂过氧化。随着注入剂量增大，两种微生物细胞受到直接刻蚀作用和间接作用损伤的程度也逐渐加剧。蔗糖密度梯度（５０ｇ／Ｌ～２００ｇ／Ｌ）离心ＤＮＡ沉降分析发现，Ｎ＋离子６０×１０１５个／ｃｍ２注入的Ｄ．ｒａｄｉｏｄｕｒａｎｓ温育４ｈ后ＤＮＡ的沉降峰仍未恢复到对照水平，这证明离子注入的直接作用不仅损伤了ＤＮＡ，而且导致了ＤＮＡ的双链断裂，用ＤＮＡ损伤修复抑制剂咖啡因和Ｎａ２－ＥＤＴＡ处理注入后的细胞，所测存活率下降的结论进一步说明了注入离子对细胞的直接刻蚀作用是导致ＤＮＡ损伤和生物诱变的直接原因。The action of 20 keV N + ion on Deinococcus radiodurans and E.coli was investigated by means of scanning electron microscope(SEM) and electron spin resonance(ESR). The results showed that ion implantation exerted direct etching damage and indirect free radicals action by energy deposition on the cells of the two microbes. The DNA damage and biological mutation resulted mainly from the etching action of injected ions; the free radicals resulted chiefly in the damage of peroxidation of biological macromolecule and membrane lipids except of DNA. Moreover, the damages in D.radiodurans and E.coli by etching and free radicals action aggravated gradually with increasing doses. The sedimentation patterns of tritiated DNA materials in D.radiodurans by neutral sucrose gradient(50—200 g/L) indicated that DNA sedimentation peak of cells incubated for 4 h did not resume control state after the implantation of 60×10 15 N + ions injection per cm 2, proving that the direct action of implanted ions led to DNA damage; the survival rate of the implanted D.radiodurans and E.coli lowered after 2 mol/L caffeine and 0.5 mmol/L EDTA treatment, confirming that the etching action of implanted ions was the direct cause resulting in DNA damage and organism mutation.

关 键 词：离子注入 微生物细胞 刻蚀作用 损伤修复抑制剂 

分 类 号：Q274[生物学—细胞生物学] Q691.5