Abstract: Abstract: We used technology of Ultraviolet Spectrophotometry and Agarose Gel Electrophoresis to analyze DNA damage under Pb2 + and Cd2 + stress in Dugesia japonica’somatic cell，and DNA damage repair by lixivium of green beans． The concentration of Pb2 + and Cd2 + were respectively120 mg /L ( Pb( NO3)2) and 1 mg /L ( CdCl2) ．We also added control groups with lixivium of green beans to repair the damaged DNA． Planaria were exposed to 24 hours and extracted using method of Proteinase K ． Though the analysis of experimental data． The results show that Lead and cadmium can induce DNA-DNA cross-linking and cut the DNA into smaller snippet． It had a better effect with the lixivium of green beans for damage repair caused by Cd2 + stress． For DNA damage caused by Pb2 + stress，it also had a better effect if we added the green beans lixivium at the same time with Pb( NO3)2 . The reason is probable because the lixivium can precipitate Pb2 + ． But in control group which we added the lixivium afterdamage，there had not repairable effect in DNA damage．

Key words:  DNA damnification, Dugesia japonica, Pb2 + 、Cd2 + stress, mung bean lixivium, damage repair

摘要： 摘要: 以日本三角涡虫( Dugesia japonica) 为实验材料，采用急性毒性实验研究Pb2 + 、Cd2 + 胁迫下日本三角涡虫体细 胞DNA 损伤情况以及绿豆浸出液对DNA 损伤的保护和修复机制。采用浓度为120 mg /L 的Pb( NO3 ) 2 和1 mg /L 的CdCl2 溶液分别处理涡虫，紫外分光光度法和琼脂糖凝胶电泳检测24 h 后三角涡虫DNA 损伤情况。同时增加 由绿豆浸出液进行修复的2 组对照以研究绿豆对于DNA 重金属损伤后的修复作用和效果。结果表明，Pb2 + 、Cd2 + 胁迫使日本三角涡虫DNA 交联程度增加，并引起DNA 链的断裂; 绿豆浸出液对于由Cd2 + 胁迫引起的DNA 损伤修 复作用较好。而对于Pb2 + 胁迫，在绿豆浸出液与Pb2 + 同时培养的对照组中，推测该浸出液可能使Pb2 + 形成沉淀从 而减小Pb2 + 浓度，因此使DNA 损伤修复具有较好效果，对已经由Pb2 + 胁迫造成损伤的DNA，修复作用不大。

关键词: DNA 损伤, 日本三角涡虫, Pb2 + 、Cd2 + 胁迫, 绿豆浸出液, 损伤修复