Gasc A M, Giammarinaro P, Ton-Hoang B, Geslin P, van der Giezen M, Sicard M
Laboratoire de Microbiologie et Génétique Moléculaire du CNRS, Toulouse, France.
Microb Drug Resist. 1997 Spring;3(1):65-72. doi: 10.1089/mdr.1997.3.65.
Fragmentation of Streptococcus pneumoniae genomic DNA with low-frequency-cleavage restriction endonucleases and separation of the fragments by field-inversion gel electrophoresis (FIGE) provides a DNA-fingerprint of a strain. This method enables us to construct a physical and genetic map of the R6 laboratory strain what will be presented. The origin of replication containing several Dna boxes was located in the dnaA region. It was of interest to compare the profiles of subclones. Two clones of strain R36A (R6 and C13) were cultivated separately for more than 15,000 generations in two laboratories. FIGE profiles differed by only one band. Another R36A descendant, isolated in 1958 by Ravin, strain Rx was of interest since it was deficient in Dpn restriction enzymes and methylases and in the hex B function. Its origin was questionable; its profile is identical to others R6 descendants, demonstrating that Rx is derived from R36A. FIGE analysis was carried out on several penicillin-resistant strains of type 9V because penicillin-resistance in this type increased recently. The profiles of a collection of a number of these resistant isolates were very similar, showing that they result from a clone. The profiles of penicillin sensitive isolates of the same type are very similar to the resistant isolates. This suggests that the 9V type has spread recently from a clone, and the resistance genes have mutated and were selected when penicillin was extensively used.
用低频切割限制内切酶切割肺炎链球菌基因组DNA，并通过场反转凝胶电泳（FIGE）分离片段，可提供菌株的DNA指纹图谱。该方法使我们能够构建将展示的R6实验室菌株的物理和遗传图谱。含有多个Dna框的复制起点位于dnaA区域。比较亚克隆的图谱很有意义。菌株R36A的两个克隆（R6和C13）在两个实验室分别培养了超过15000代。FIGE图谱仅相差一条带。另一个R36A后代，由拉文于1958年分离得到的菌株Rx很受关注，因为它缺乏Dpn限制酶和甲基化酶以及hex B功能。其起源存在疑问；它的图谱与其他R6后代相同，表明Rx源自R36A。对几种9V型耐青霉素菌株进行了FIGE分析，因为该型中的青霉素抗性最近有所增加。许多这些抗性分离株的集合图谱非常相似，表明它们来自一个克隆。同一类型的青霉素敏感分离株的图谱与抗性分离株非常相似。这表明9V型最近从一个克隆传播而来，并且在青霉素广泛使用时，抗性基因发生了突变并被选择。
