• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Microbiology >Pre- and Post-irradiation Effects upon Lethality and Reversion in Salmonella typhimurium
【24h】

Pre- and Post-irradiation Effects upon Lethality and Reversion in Salmonella typhimurium

机译：对杀伤性和逆转后的乳突和逆转后的辐照效应

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Summary: Lag, exponential and stationary phase cells of Salmonella typhimurium LT-2 trpC3) grown in nutrient broth or tryptophan-supplemented minimal medium were irradiated with doses of u.v. up to 570 ergs/mm2. Casein hydrolysate supplementation of the post-irradiation plating medium causes enhanced survival only for lag and exponential phase broth-grown and exponential phase minimal-grown cells. Caffeine invariably leads to decreased survival levels and abolition of any casein hydrolysate enhancement of survival. Cells of all six growth conditions give induced Trp+ reversions, often due to suppressor mutations, on plating media containing casein hydrolysate. Only for minimal-grown lag and exponential phase cells do any induced Trp+ appear on media devoid of casein hydrolysate supplementation. In these cases too, caffeine has a definite antimutagenic action. Mutation frequency decline (MFD) experiments revealed that those cells exhibiting a casein hydrolysate enhancement of survival on plates also show a delayed onset of MFD and a fall of survival, after an initial delay, in liquid minimal medium. MFD experiments in liquid do not give a complete quantitative explanation for the Trp+ revertant yields found on plates. We suggest that intracellular free amino acid pool sizes may be a common factor in the correlations which we have observed.
机译：发明内容：以营养肉汤或色氨酸补充的最小​​培养基生长的Salmonella Typhimurium LT-2 Trpc3的滞后，指数和固定相细胞用剂量的U.V照射。高达570 ergs / mm2。酪蛋白水解产物后照射后电镀介质仅导致增强的存活仅用于滞后和指数液相肉汤生长和指数相位最小生长的​​细胞。咖啡因总是导致减少存活水平，并取消任何酪蛋白水解产物的存活率。所有六种生长条件的细胞赋予诱导的TRP +逆转，通常是由于抑制剂突变，含有酪蛋白水解产物的电镀培养基。仅用于最小生长的​​滞后和指数相位细胞，任何诱导的TRP +出现在没有酪蛋白水解产物补充的培养基上。在这些情况下，咖啡因也有一个明确的抗矫正作用。突变频率下降（MFD）实验表明，那些表现出酪蛋白水解的细胞在平板上存活的增强也显示出MFD的延迟发作和在液体最小介质中初始延迟后存活的下降。 MFD在液体中的实验不给出在板上发现的TRP +回复产率的完全定量解释。我们建议细胞内游离氨基酸池尺寸可以是我们观察到的相关性的常见因素。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号