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RISS 인기검색어
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- 저자 : Ruifu Yang (검색결과 3 건)
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Soft sweep development of resistance in Escherichia coli under fluoroquinolone stress
Xianxing Xie,Ruichen Lv,Chao Yang,Yajun Song,Yanfeng Yan,Yujun Cui,Ruifu Yang 한국미생물학회 2019 The journal of microbiology Vol.57 No.12
We employed a stepwise selection model for investigating the dynamics of antibiotic-resistant variants in Escherichia coli K-12 treated with increasing concentrations of ciprofloxacin (CIP). Firstly, we used Sanger sequencing to screen the variations in the fluoquinolone target genes, then, employed Illumina NGS sequencing for amplicons targeted regions with variations. The results demonstrated that variations G81C in gyrA and K276N and K277L in parC are standing resistance variations (SRVs), while S83A and S83L in gyrA and G78C in parC were emerging resistance variations (ERVs). The variants containing SRVs and/or ERVs were selected successively based on their sensitivities to CIP. Variant strain 1, containing substitution G81C in gyrA, was immediately selected following ciprofloxacin exposure, with obvious increases in the parC SRV, and parC and gyrA ERV allele frequencies. Variant strain 2, containing the SRVs, then dominated the population following a 20× increase in ciprofloxacin concentration, with other associated allele frequencies also elevated. Variant strains 3 and 4, containing ERVs in gyrA and parC, respectively, were then selected at 40× and 160× antibiotic concentrations. Two variants, strains 5 and 6, generated in the selection procedure, were lost because of higher fitness costs or a lower level of resistance compared with variants 3 and 4. For the second induction, all variations/indels were already present as SRVs and selected out step by step at different passages. Whatever the first induction or second induction, our results confirmed the soft selective sweep hypothesis and provided critical information for guiding clinical treatment of pathogens containing SRVs.
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DNA Microarray-Based Global Transcriptional Profiling of Yersinia pestis in Multicellularity
Jingfu Qiu,Zhaobiao Guo,Haihong Liu,Dongsheng Zhou,Yanping Han,Ruifu Yang 한국미생물학회 2008 The journal of microbiology Vol.46 No.5
Yersinia pestis, the causative agent of plague, has a feature of forming multicellular aggregates at liquid-air interface around the wall of glass tube. In this study, we employed the whole-genome DNA microarray of Y. pestis to investigate the global transcriptional profile in multicellularity compared with that in its planktonic growth. A total of 177 genes were differentially expressed in Y. pestis during early stage of multicellular formation; Seventy genes of them were up-regulated while 107 down-regulated. In addition to a large number of genes encoding unknown functions, most of the induced genes encode cell envelope and transport/binding proteins. The up-regulation of amino acid biosynthesis, the differentially altered genes that are involved in virulence, and the cold shock protein genes were for the first time reported to be associated with the multicellular formation. Our results revealed the global gene expression of Y. pestis were changed in the formation of multicellularity, providing insights into the molecular mechanism of multicellular behaviour, which need investigating further.
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Parallel Gene Loss and Acquisition Among Strains of Different Brucella Species and Biovars
Zhijun Zhong,Yufei Wang,Jie Xu,Yanfen Chen,Yuehua Ke,Xiaoyan Zhou,Xitong Yuan,Dongsheng Zhou,Yi Yang,Ruifu Yang,Guangneng Peng,Hai Jiang,Jing Yuan,Hongbin Song,Buyun Cui,Liuyu Huang,Zeliang Chen 한국미생물학회 2012 The journal of microbiology Vol.50 No.4
The genus Brucella is divided into six species; of these, B. melitensis and B. abortus are pathogenic to humans, and B. ovis and B. neotomae are nonpathogenic to humans. The definition of gene loss and acquisition is essential for understanding Brucella’s ecology, evolutionary history, and host relationships. A DNA microarray containing unique genes of B. melitensis Type strain 16MT and B. abortus 9-941 was constructed and used to determine the gene contents of the representative strains of Brucella. Phylogenetic relationships were inferred from sequences of housekeeping genes. Gene loss and acquisition of different Brucella species were inferred. A total of 214 genes were found to be differentially distributed,and 173 of them were clustered into 15 genomic islands (GIs). Evidence of horizontal gene transfer was observed for 10GIs. Phylogenetic analysis indicated that the 19 strains formed five clades, and some of the GIs had been lost or acquired independently among the different lineages. The derivation of Brucella lineages is concomitant with the parallel loss or acquisition of GIs, indicating a complex interaction between various Brucella species and hosts.
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