AT细胞DNA双链断裂重接修复效率及其忠实性

用脉冲电场凝胶电泳和双标记基因质粒ＤＮＡ转染技术研究辐射敏感的毛细血管扩张性共济失调症患者皮肤成纤维细胞（ＡＴ５ＢＩＶＡ）和正常辐射抗性的人宫颈癌细胞（ＨｅＬａＳ３）ＤＮＡ双链断裂重接修复率及其忠实性。结果表明γ射线照射诱发ＤＮＡ双链断裂的产额和重接修复率，在两株细胞间无差别．而ＡＴ细胞对导入的限制性内切酶ＥｃｏＲＶ产生双链断裂质粒ＤＮＡ的重接修复忠实性显著低于ＨｅｌａＳ３ｔｅ胞，表明ＡＴ细胞易发生ＤＮＡ错误修复，这很可能就是ＡＴ细胞高度辐射敏感性的主要原因。

The Repair Efficiency and Fidelity of DNA Double-strand Break Rejoning in AT Cells

The repair efficiencies of DNA double-strand break rejoining were assessed in radiation-sensitive ATSBIVA cells and radioresistance HeLa S3 cells by pulsed field gel electrophoresis. DNA errorprone repair was considered probably to be the main cause of hypersensitivity to gamma radiation in AT cells. The results indicated that the intial production and the rejoining efficiency of ionizing radiationinduced DNA double-strand breaks were similar in two cell lines.However. ATSBIVA cells showed a significantly reduced fidelity of rejoining DNA double-strand breaks cut by restriction endonuclease EcoR V in transferred vector DNA. The plasmid dublemarked with neo and gpt genes was transfered into both kinds of cells and the fidelity of DNA double-strand break rejoining was examined