霍乱弧菌超级整合子的微进化及对霍乱弧菌环境适应性作用的研究

项目名称： 霍乱弧菌超级整合子的微进化及对霍乱弧菌环境适应性作用的研究

项目编号： No.30800987

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 逄波

作者单位： 中国疾病预防控制中心传染病预防控制所

项目金额： 20万元

中文摘要： 细菌整合子对基因尤其是耐药基因在菌间水平传递发挥重要作用，霍乱弧菌携带二百多个基因的超级整合子（SI），不仅携带耐药基因，且大多数基因功能未明。我们对流行以及非流行菌株的比较基因组杂交以及国外初步的研究发现:SI的变异极大地影响了霍乱弧菌整体稳定性分析。为研究霍乱弧菌SI微进化和其在霍乱弧菌环境适应中的作用，采用PCR扫描分析我国不同霍乱流行时期的优势型别的霍乱弧菌，绘制了实验菌株SI的扫描图谱，发现实验菌株SI中大部分基因盒的排列结构具有共线性的特点，但不同流行年代菌株的SI仍具有明显的多样性。多样性的表现形式包括序列插入、替换和缺失。这些变异通过重复序列、VCR之间的重组所介导。同时获得了实验菌株SI中新的基因的信息，新的基因来自不同血清群的霍乱弧菌或者近缘的拟态弧菌，说明霍乱流行中菌株的SI中的基因盒流动持续存在。基于荧光PCR方法的转录组研究结果显示，与在LB培养基中培养相比，在胆盐、AKI培养条件下，SI中少量ORF转录水平出现变化，而M9培养条件下，SI中大部分ORF的转录水平明显升高，其中功能与DNA代谢和脂类代谢相关，可见SI与菌株在低营养状态下的适应性生存密切相关。

中文关键词： 霍乱弧菌；超级整合子；变异；基因盒；转录

英文摘要： Bacterial integron play important role in gene especially antibiotic resistant gene transfers. The superintegron (SI) carried by Vibrio cholerae consists of more than 200 genes with most of which the function is unknown. Our previous investigation focusing on epidemic and non-epidemic strains indicated that the diversity of SI greatly influenced the stability of the V. cholerae genome. In order to investigate the micro-evolution of SI and the role of SI in V. cholerae environment adaption, PCR scanning was employed to explore the SI diversity of the predominant strains in different cholera epidemics.Structrual map of the SI in the test strains were drawn based on the PCR scanning result. The arrangement of gene cassette in different SI exhibited syntenic character. However,obvious divesity was observed.The diversity included sequence insertion, replacement and deletion.These diversity was mediated by recombination between repeat sequence and VCR. Our result also indicated gene cassettes could be transferred between different serogroups of V. cholerae even V. mimicus. The transcriptome based on real-time PCR indicated the transcription of a few of the ORF were up-regulated cultured in bile salt and AKI media compared to that of LB media. However, the transcription of most of the ORFs in SI, whose function were related to DNA and lipid metabolism, were up-regulated in M9 meida compared to that of LB media.We concluded that SI is closely related to the adaption of V. cholerae in nutrition deprived circumstance.

英文关键词： Vibrio cholerae; superintegron;diversity; gene cassette;transcription