MOLECULAR NATURE OF R-FACTORS
MOLECULAR NATURE OF R-FACTORS
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DOI：
10.1016/s0022-2836(66)80097-9
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发表时间：
1966-01-01
影响因子：
5.6
通讯作者：
WATANABE, T
中科院分区：
文献类型：
--
作者：
FALKOW, S;CITARELL.RV;WATANABE, T
奇异变形杆菌感染性多重耐药因子的获得与添加一个或多个物理可识别的天然卫星DNA片段相关。由R-因子携带的一种或多种耐药特征的自发丧失与卫星DNA的特定密度区域的明显丧失或卫星DNA的不同级分的相对量的变化相关。氯霉素抗性特征的丧失伴随着56%的G + C DNA片段的消失。R-因子的抗性转移因子组分以及四环素抗性特征被发现与总G + C含量为49 ± 1%的DNA片段相关。另一方面，磺胺、链霉素和卡那霉素抗性特征与50 - 54%G + C组成的DNA片段相关。同时考虑了DNA丢失和耐药性的两种替代机制：重组和突变（缺失）。这项研究的结果支持删除假说。R-因子可以根据其对大肠杆菌性因子的抑制作用进行遗传分化，但不能根据其DNA在氯化铯密度梯度中的带型进行分化。
The acquistion of infectious multiple drug resistance factors by Proteus mirabilis was correlated with the addition of one or more physically recognizable, native, satellite DNA fractions. The spontaneous loss of one or more drug resistance characteristics carried by R-factors was correlated with either an apparent loss of particular density regions of the satellite DNA or a change in the relative amounts of the different fractions of the satellite DNA. Loss of the chloramphenicol resistance characteristic was accompanied by a disappearance of 56% G + C DNA fragments. The resistance transfer factor component of R-factors, as well as the tetracycline resistance characteristic, were found to be associated with DNA fragments with an over-all G + C content of 49 + 1%. The sulfonamide, streptomycin and kanamycin resistance characteristics, on the other hand, were associated with DNA fragments of 50 to 54% G + C composition. Two alternative mechanisms for the concomitant loss of DNA and drug resistance were considered: recombination and mutation (deletion). The results of this investigation favor the deletion hypothesis. R-factors which may be differentiated genetically on the basis of their inhibition of the Escherichia coli sex factor could not be differentiated by the banding patterns of their DNA in cesium chloride density gradients.