| 1. | After iptg induction , the lexa protein was significantly expressed in the strain jm109 ( pza172 ) , and the survival rate of this strain was lower than that of the control strain jm109
抗辐射菌lexa基因在大肠杆菌细胞中，经iptg诱导能稳定地表达， lexa基因的显著表达降低了大肠杆菌经射线照射和mmc作用后的存活率。 |
| 2. | The expression of deinococcus radiodurans lexa gene in escherichia coli resulted in the increase of sensitivity of the latter to dna toxins y - rays and mmc , although the mechanism of this effect is not clear
抗辐射菌lexa基因在大肠杆菌中的显著表达降低了大肠杆菌对射线和mmc的抗性，其作用机理还有待于进一步的研究。 |
| 3. | This resistance is known to be due to deinococcus radiodurans " extremely proficient dna repair pathway employed by this organism . also , the exsistence of sos response and characterization of deinococcus radiodurans lexa protein remains unclear
抗辐射菌中是否存在sos修复路径，及在大肠杆菌等菌中广泛存在的lexa蛋白在抗辐射菌中的功能特性如何均是未解之谜。 |
| 4. | In this study , lexa mutant of deinococcus radiodurans xe has been successfully constructed . the survival curve of this strain was measured using colony formation assay after treatment with different doses of radiation and different times of mmc
本研究利用已构建的抗辐射菌lexa基因突变体菌株xe ，经受不同剂量射线照射和不同时间的mmc作用，平板菌落计数，绘制存活曲线。 |
| 5. | The expression of lexa protein in the iptg - induced jm109 ( pza172 ) was checked by sds - page , and the survival curve of this strain was measured using colony formation assay after treatment with different doses of radiation and different concentrations of mmc
应用电穿孔技术将携带有抗辐射菌lexa基因的重组质粒pza172转入大肠杆菌jm109 ，其启动子为lacz ，用iptg诱导， sds - page凝胶电泳检测lexa蛋白的表达。 |
| 6. | In this study , dna strand breaks in jm109 cells caused by - rays and the protective effect of lexa protein of deinococcus radiodurans have been studied by fluorometric assay of dna unwinding . , the results indicated that the rate of dna strand breaks increased with the increase of - rays dose . however , when the concentration of lexa protein from 0 . 1 g / ml to 10 g / ml , it still showed no protective effect on dna strand breaks , then lexa protein of deinococcus radiodurans was n ' t radioprotector
本研究采用了dna解旋荧光法检测由射线所致的dna链断裂的损伤程度以及抗辐射菌lexa蛋白的辐射防护作用，在辐照前加入不同浓度的lexa蛋白，检测dna链的断裂，结果表明dna链的断裂程度随着射线辐照剂量的增加而增强，抗辐射菌lexa蛋白对射线所致dna链断裂的修复不起作用，进一步说明抗辐射菌lexa蛋白不起辐射防护作用。 |
| 7. | When compared with kds301 ( lexa + ) , xe ( lexa - ) cells showed quite similar levels of survival curve to y - irradiation and mmc , indicating lexa gene had no effect on radiation resistance of deinococcus radiodurans . deinococcus radiodurans " lexa had no revelance with its extremely radioresistance . the recombinant plasmid pza172 was constructed by cloning the lexa gene of deinococcus radiodurans into the vector plasmid puc19 in the downstream of lacz promoter
对lexa基因突变体xe的研究表明，其辐射抗性与lexa基因野生型的抗辐射菌kd8301相近，存活曲线上均显示有一个宽大的肩区，结果发现lexa基因的突变并没有改变抗辐射菌的独特抗性，说明lexa基因与辐射抗性无关。 |
