Meinersmann R J, Phillips R W, Ladely S R
Bacterial Epidemiology and Antimicrobial Resistance Research Unit, USDA Agricultural Research Service, Athens, Richard J. Russell Research Center, P.O. Box 5677, Athens, GA 30604, USA.
Syst Appl Microbiol. 2009 Apr;32(2):91-100. doi: 10.1016/j.syapm.2008.12.004. Epub 2009 Feb 6.
An intervening sequence (IVS) can be present or absent in the 23S rRNA of Campylobacter jejuni and Campylobacter coli. As part of a survey, we used a polymerase chain reaction (PCR) assay to detect the presence of the IVS in 43 isolates of C. coli and 82 isolates of C. jejuni. An IVS was present in 40 (93.0%) of the C. coli and only 34 (41.5%) of the C. jejuni isolates. Twelve (27.9%) of the C. coli isolates and seven (8.5%) of the C. jejuni isolates resulted in two polymerase chain reaction products, indicating heterogeneity in the presence of the 23S rRNA IVS. Fourteen of the isolates with two products were evaluated by pulse-field gel electrophoresis; 13 different patterns were observed. The total band size of one isolate was substantially greater than the expected 1.7 Mb, possibly indicating a mixed culture. Southern blot analyses demonstrated the expected three rRNA operons in all tested isolates. Nested PCR reactions with operon-specific primers followed by primers for the IVS confirmed that the strains of interest contained either one or two operons carrying the IVS and the remaining operon(s) did not. Sequence analysis of the IVS and flanking regions of the 23S rRNA genes did not discriminate C. jejuni and C. coli as distinct populations. These results indicate horizontal transfer of 23S rRNA genes or portions of the genes between C. jejuni and C. coli. Also, data showing sequence polymorphisms between the three 23S rRNA loci outside of the IVS region suggest that the isolates with intra-genomic heterogeneity appear to be members of clones that have an ancient defect in gene conversion mechanisms needed for concerted evolution of the ribosomal operons.
空肠弯曲菌和结肠弯曲菌的23S rRNA中可能存在或不存在间隔序列（IVS）。作为一项调查的一部分，我们使用聚合酶链反应（PCR）检测法来检测43株结肠弯曲菌和82株空肠弯曲菌中IVS的存在情况。40株（93.0%）结肠弯曲菌中存在IVS，而空肠弯曲菌分离株中只有34株（41.5%）存在IVS。12株（27.9%）结肠弯曲菌分离株和7株（8.5%）空肠弯曲菌分离株产生了两种聚合酶链反应产物，表明23S rRNA IVS的存在具有异质性。对14株产生两种产物的分离株进行了脉冲场凝胶电泳评估；观察到13种不同的图谱。其中一株分离株的总条带大小明显大于预期的1.7 Mb，可能表明是混合培养物。Southern印迹分析表明，所有测试分离株中均有预期的三个rRNA操纵子。用操纵子特异性引物随后用IVS引物进行巢式PCR反应证实，感兴趣的菌株含有一个或两个携带IVS的操纵子，其余操纵子则没有。对23S rRNA基因的IVS及其侧翼区域进行序列分析，并未将空肠弯曲菌和结肠弯曲菌区分为不同的群体。这些结果表明，23S rRNA基因或其部分基因在空肠弯曲菌和结肠弯曲菌之间发生了水平转移。此外，显示IVS区域外三个23S rRNA基因座之间序列多态性的数据表明，具有基因组内异质性的分离株似乎是克隆的成员，这些克隆在核糖体操纵子协同进化所需的基因转换机制中存在古老缺陷。
