Katayama S, Dupuy B, Daube G, China B, Cole S T
Unité de Génétique Moléculaire Bactérienne, Institut Pasteur, Paris, France.
Mol Gen Genet. 1996 Jul 26;251(6):720-6. doi: 10.1007/BF02174122.
The intron-encoded endonuclease I-CeuI from Chlamydomonas eugametos was shown to cleave the circular chromosomes of all Clostridium perfringens strains examined at single sites in the rRNA operons, thereby generating ten fragments suitable for the rapid mapping of virulence genes by pulsed-field gel electrophoresis (PFGE). This method easily distinguishes between plasmid and chromosomal localisations, as I-CeuI only cuts chromosomal DNA. Using this approach, the genes for three of the four typing toxins, beta, epsilon, and tau, in addition to the enterotoxin and lambda-toxin genes, were shown to be plasmid-borne. In a minority of strains, associated with food poisoning, where the enterotoxin toxin gene was located on the chromosome, genes for two of the minor toxins, theta and mu, were missing.
来自衣藻（Chlamydomonas eugametos）的内含子编码内切核酸酶I-CeuI已被证明能在所有检测的产气荚膜梭菌（Clostridium perfringens）菌株的环状染色体上，于rRNA操纵子的单个位点进行切割，从而产生十个片段，适用于通过脉冲场凝胶电泳（PFGE）快速定位毒力基因。由于I-CeuI仅切割染色体DNA，该方法能轻松区分质粒和染色体定位。采用这种方法，除了肠毒素和λ-毒素基因外，四种分型毒素中的三种，即β、ε和τ的基因，被证明是由质粒携带的。在少数与食物中毒相关的菌株中，肠毒素基因位于染色体上，两种次要毒素θ和μ的基因缺失。
