Burkholderia mallei is the etiologic agent of glanders in solipeds and humans. Lipopolysaccharide (LPS) is a major component of cell envelop of this pathogen. O-antigen, the most external component of LPS, is a virule...Burkholderia mallei is the etiologic agent of glanders in solipeds and humans. Lipopolysaccharide (LPS) is a major component of cell envelop of this pathogen. O-antigen, the most external component of LPS, is a virulence factor and a protective antigen in many pathogenic bacteria. Two putative proteins named Wzm (integral membrane protein) and Wzt (hydrophilic ATP-binding protein) are believed to make up an ABC-2 transporter of B. mallei that facilitates transport of components of O-antigen from cytosol to outer-membrane. We studied the importance of wzt (encoding Wzt) to growth, LPS O-antigen profile, and pathogenicity of B. mallei. A wzt mutant strain was generated by deleting a portion of the wzt in B. mallei wild type strain ATCC 23344 by gene replacement. Compared to the wild type strain, the wzt mutant displayed slower growth in vitro and less lethality in CD1 mice when inoculated intraperitoneally. The 50% lethal doses (LD50) of the wild type and the wzt mutant strains were 5.9 × 105 and 9.1 × 105 cfu, respectively. CD1 mice inoculated with a non-lethal dose of the wzt mutant produced specific serum immunoglobulins IgG1 and IgG2a and were partially protected against challenge with 11.2 times LD50 of the wild type strain. These findings suggest that the wzt is required for optimal in vitro growth and pathogenesis of B. mallei, and a wzt mutant protects CD1 mice against glanders.展开更多
Since the logarithmic form of Shannon entropy has the drawback of undefined value at zero points,and most existing threshold selection methods only depend on the probability information,ignoring the within-class unifo...Since the logarithmic form of Shannon entropy has the drawback of undefined value at zero points,and most existing threshold selection methods only depend on the probability information,ignoring the within-class uniformity of gray level,a method of reciprocal gray entropy threshold selection is proposed based on two-dimensional(2-D)histogram region oblique division and artificial bee colony(ABC)optimization.Firstly,the definition of reciprocal gray entropy is introduced.Then on the basis of one-dimensional(1-D)method,2-D threshold selection criterion function based on reciprocal gray entropy with histogram oblique division is derived.To accelerate the progress of searching the optimal threshold,the recently proposed ABC optimization algorithm is adopted.The proposed method not only avoids the undefined value points in Shannon entropy,but also achieves high accuracy and anti-noise performance due to reasonable 2-D histogram region division and the consideration of within-class uniformity of gray level.A large number of experimental results show that,compared with the maximum Shannon entropy method with 2-D histogram oblique division and the reciprocal entropy method with 2-D histogram oblique division based on niche chaotic mutation particle swarm optimization(NCPSO),the proposed method can achieve better segmentation results and can satisfy the requirement of real-time processing.展开更多
目的:构建猪链球菌2型(Streptococcus suis type 2)强毒株05ZYH3389K毒力岛上的ABC转运蛋白gene0910敲除突变体,并初步分析其活性,为进一步研究猪链球菌假想毒力因子在致病中的作用提供实验基础。方法:以猪链球菌2型05ZYH33基因组为模板...目的:构建猪链球菌2型(Streptococcus suis type 2)强毒株05ZYH3389K毒力岛上的ABC转运蛋白gene0910敲除突变体,并初步分析其活性,为进一步研究猪链球菌假想毒力因子在致病中的作用提供实验基础。方法:以猪链球菌2型05ZYH33基因组为模板,扩增gene0910两侧各约500bp左右的片段为上下游同源臂,以pSET1质粒为模板,扩增氯霉素抗性基因Cm为中间片段,采用重叠PCR方法搭建三个片段,并克隆到自杀载体pSET4S上,构建基因敲除的载体。电转化05ZYH33感受态细胞,经30℃双交换和40℃质粒丢失,最后点板法筛选出基因敲除突变体△0910。对突变株和野生株的生物学活性及小鼠的致病性进行了初步比较。结果:PCR分析和测序结果均显示gene0910完全被氯霉素抗性基因Cm所替代,基因敲除突变体构建成功。结论:突变株的生物学活性和对小鼠的致病性与野生株相比差异不显著。展开更多
文摘Burkholderia mallei is the etiologic agent of glanders in solipeds and humans. Lipopolysaccharide (LPS) is a major component of cell envelop of this pathogen. O-antigen, the most external component of LPS, is a virulence factor and a protective antigen in many pathogenic bacteria. Two putative proteins named Wzm (integral membrane protein) and Wzt (hydrophilic ATP-binding protein) are believed to make up an ABC-2 transporter of B. mallei that facilitates transport of components of O-antigen from cytosol to outer-membrane. We studied the importance of wzt (encoding Wzt) to growth, LPS O-antigen profile, and pathogenicity of B. mallei. A wzt mutant strain was generated by deleting a portion of the wzt in B. mallei wild type strain ATCC 23344 by gene replacement. Compared to the wild type strain, the wzt mutant displayed slower growth in vitro and less lethality in CD1 mice when inoculated intraperitoneally. The 50% lethal doses (LD50) of the wild type and the wzt mutant strains were 5.9 × 105 and 9.1 × 105 cfu, respectively. CD1 mice inoculated with a non-lethal dose of the wzt mutant produced specific serum immunoglobulins IgG1 and IgG2a and were partially protected against challenge with 11.2 times LD50 of the wild type strain. These findings suggest that the wzt is required for optimal in vitro growth and pathogenesis of B. mallei, and a wzt mutant protects CD1 mice against glanders.
基金Supported by the CRSRI Open Research Program(CKWV2013225/KY)the Priority Academic Program Development of Jiangsu Higher Education Institution+2 种基金the Open Project Foundation of Key Laboratory of the Yellow River Sediment of Ministry of Water Resource(2014006)the State Key Lab of Urban Water Resource and Environment(HIT)(ES201409)the Open Project Program of State Key Laboratory of Food Science and Technology,Jiangnan University(SKLF-KF-201310)
文摘Since the logarithmic form of Shannon entropy has the drawback of undefined value at zero points,and most existing threshold selection methods only depend on the probability information,ignoring the within-class uniformity of gray level,a method of reciprocal gray entropy threshold selection is proposed based on two-dimensional(2-D)histogram region oblique division and artificial bee colony(ABC)optimization.Firstly,the definition of reciprocal gray entropy is introduced.Then on the basis of one-dimensional(1-D)method,2-D threshold selection criterion function based on reciprocal gray entropy with histogram oblique division is derived.To accelerate the progress of searching the optimal threshold,the recently proposed ABC optimization algorithm is adopted.The proposed method not only avoids the undefined value points in Shannon entropy,but also achieves high accuracy and anti-noise performance due to reasonable 2-D histogram region division and the consideration of within-class uniformity of gray level.A large number of experimental results show that,compared with the maximum Shannon entropy method with 2-D histogram oblique division and the reciprocal entropy method with 2-D histogram oblique division based on niche chaotic mutation particle swarm optimization(NCPSO),the proposed method can achieve better segmentation results and can satisfy the requirement of real-time processing.
文摘目的:构建猪链球菌2型(Streptococcus suis type 2)强毒株05ZYH3389K毒力岛上的ABC转运蛋白gene0910敲除突变体,并初步分析其活性,为进一步研究猪链球菌假想毒力因子在致病中的作用提供实验基础。方法:以猪链球菌2型05ZYH33基因组为模板,扩增gene0910两侧各约500bp左右的片段为上下游同源臂,以pSET1质粒为模板,扩增氯霉素抗性基因Cm为中间片段,采用重叠PCR方法搭建三个片段,并克隆到自杀载体pSET4S上,构建基因敲除的载体。电转化05ZYH33感受态细胞,经30℃双交换和40℃质粒丢失,最后点板法筛选出基因敲除突变体△0910。对突变株和野生株的生物学活性及小鼠的致病性进行了初步比较。结果:PCR分析和测序结果均显示gene0910完全被氯霉素抗性基因Cm所替代,基因敲除突变体构建成功。结论:突变株的生物学活性和对小鼠的致病性与野生株相比差异不显著。
