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离子注入对微生物细胞的刻蚀与对DNA的损伤及修复 |
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宋道军 姚建铭 吴丽芳 王纪 涂友斌 余增亮
摘 要： 以耐辐射异常球菌为试材，以E. coli 为对照，用显微扫描电镜和3H-TdR标记，研究了离子注入对微生物细胞的刻蚀与对DNA的损伤及其修复。结果表明，注入离子对细胞存在着刻蚀损伤；中性蔗糖梯度密度离心沉降分析证明, 大剂量下离子注入可直接导致DNA损伤，并观察到在对应的存活率峰值注入剂量下，D. radiodurans修复损伤DNA的能力比E. coli 强，还证明了细胞经不同时间温育后，损伤的DNA分子得到了部分修复。
关键词: 离子注入;耐辐射异常球菌;SEM观察;3H-TdR标记;DNA损伤与修复
中图分类号: Q345 文献标识码: A 文章编号: 0253-9772(1999)04-0037-40
The Etching of Cells and Damage and Repair of DNA
in Deinococcus radiodurans by N+Implantation
SONG Dao-jun, YAO Jian-ming, WU Li-fang,WANG Ji, TU You-bin, YU Zeng-liang
(Centre of Ion Beam Bioengineering,Institute of Plasma Physics,Academia Sinica,P. O. Box 1126,Hefei230031,China)
Abstract： The direct action of N+implantationin on D. radioduransand E. coliwas investigated by SEM, and their cells were labeled with 3H-TdR, which were implanted by 20keV N+after incubation 18hours, then the DNA of lysed cells was subjected to the neutral sucrose gradient(5%～20%) ultra-centrifugation sedimentation analysis. The results showed that N+implantation exerted direct action on two kinds of microorganisms; the momentum transfer and energy deposition of implantation ions produced the direct etching damage on cells, and repair DNA efficiency of D.radiodurans was higher than that of E. coli. Meanwhile, the damaged DNA incomplete repairing was observed. When incubation was continued up to 6 hours, the rejoined DNA molecules broke again. The repair of damaged DNA could be inhibited by 200μg/ml chloramphenicol. This suggested that DNA damage was serious by ion implantation and damaged DNA repair of cells need continuously synthesizing repair enzyme.
Key words： Ion implantation;Deinococcus radiodurans;SEM;Radio-labeling;Centrifugation of neutral sucrose gradient;DNA damage and repair
电离辐射可引起细胞膜脂过氧化并导致DNA损伤已被证实〔1〕。研究表明，低剂量辐射主要引起DNA单链损伤，随剂量的增大，受照细胞DNA由单链到双链断裂的比率也逐渐提高〔2〕。但在适宜条件下，不同辐射剂量和不同辐射敏感性生物，受损伤的DNA可得到不同程度地修复〔1〕。另一方面，八十年代中期兴起于我国的低能离子束[1] [2] 下一页
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