铜绿假单胞菌液体发酵产生絮凝现象的研究

对铜绿假单胞菌液体发酵产生的絮凝现象进行了研究。初步确定其由铜绿假单胞菌产生的生物膜引起,测得生物膜中多糖含量约为6.3%,蛋白质含量约为7.7%。考察了添加颗粒营养物质豆饼粉对絮凝现象的影响,分析了天然群体感应抑制剂水杨酸、丁香酚、儿茶素、姜黄素和大蒜提取物对生物膜和菌浓的影响以及群体感应淬灭酶对菌浓的影响。结果显示,添加颗粒营养物质对絮凝物影响不显著;天然群体感应抑制剂不能显著提高铜绿假单胞菌液体发酵菌浓,但对生物膜的分散具有一定作用;群体感应淬灭酶对铜绿假单胞菌液体发酵浓度无显著影响。     

中草药对铜绿假单胞菌及其群体感应抑制作用

为了筛选对多重耐药铜绿假单胞菌具有抑菌作用的中草药,并筛选铜绿假单胞菌的群体感应蛋白LasR的抑制剂,本实验利用纸片扩散法对59株临床分离的铜绿假单胞菌和1株PAO1进行抗生素药敏试验,并对其中3株菌进行中草药提取物体外抑菌试验,通过检测报告质粒中β-半乳糖苷酶的活性来筛选LasR蛋白抑制剂。实验发现,丁香、赤芍等中药粗提物具有良好的抑菌效果,部分中草药可通过影响LasR蛋白的水溶性或信号分子与受体蛋白的结合来实现对细菌群体感应的调控。     

铜绿假单胞菌多重耐药性分子机制的研究

铜绿假单胞菌是重要的医院感染条件致病菌.由于各种抗生素的广泛使用,细菌耐药问题日趋严重,导致了铜绿假单胞菌产生了很强的耐药性而且多重耐药,铜绿假单胞菌通过多种途径产生耐药.而从分子水平对其耐药性机制进行研究具有重要意义.     

铜绿假单胞菌毒力相关小RNA的筛选与鉴定

小RNA在细菌的基因调控过程中具有重要的作用,然而目前在铜绿假单胞菌中仅发现了几种有功能的小RNA.铜绿假单胞菌中存在着许多短片段RNA(100-250 bp),然而这些短片段RNA的功能尚不清楚.为了筛选与铜绿假单胞菌毒力相关的小RNA,结合生物信息学手段和实验检测技术对这些短片段RNA进行了靶点基因预测及相关表型研究.结果显示:利用小RNA靶点预测软件,筛选到23个毒力相关小RNA;通过构建小RNA过表达质粒,对这些小RNA进行了高表达及相关的表型检测,发现Pant116对铜绿假单胞菌的3型分泌系统具有负调控作用.     

应用RAPD技术研究金黄色葡萄球菌和铜绿假单胞菌DNA的多态性

本试验利用RAPD技术对临床上重要的致病菌金黄色葡萄球菌28株和铜绿假单胞菌2l株，用10bp引物进行扩增，结果铜绿假单胞菌和金黄色葡萄球菌的DNA带谱均出现了多态性；根据带谱的不同可将铜绿假单胞菌分成8个型，金葡菌分成3个型；根据铜绿假单胞菌的带型计算各菌间的相似系数，依此系数绘制了系统树，从系统树中清晰可见各菌间的亲缘关系。     

烧伤病房感染患者铜绿假单胞菌的分离及耐药性分析

目的 了解烧伤病房感染患者铜绿假单胞菌耐药谱的变化,为防治烧伤病区患者感染铜绿假单胞菌提供合理用药依据.方法 常规方法收集同一时间烧伤病房9名感染患者的患部浓汁和血液标本,分离鉴定出9株铜绿假单胞菌,K-B法进行药敏试验及统计学分析.结果 9株铜绿假单胞菌对氨苄西林、哌拉西林、亚胺培南/西司他丁、头孢他啶、氨曲南、阿米卡星、复方磺胺等11种抗菌药物耐药率均为100%.结论 烧伤病房感染患者铜绿假单胞菌耐药现象严重,应注意铜绿假单胞菌耐药性的监测.     

铜绿假单胞菌的耐药现状及外膜孔蛋白分析

目的:总结分析我院2007年-2009年铜绿假单胞菌对常用抗生素的耐药状况,以指导临床合理选用抗生素,同时探讨外膜孔蛋白缺失介导的铜绿假单胞菌对亚胺培南的耐药机制.方法:采用PCR方法检测外膜孔蛋白OprD的编码基因,利用Whonet 5.4 软件对药敏资料进行统计分析.结果:3年中铜绿假单胞菌每年的分离数量分别为13...     

铜绿假单胞菌下呼吸道感染的临床分析

目的 :分析和总结铜绿假单胞菌下呼吸道感染的临床特点及抗生素敏感性的分布情况。方法 :对 2 8例铜绿假单胞菌下呼吸道感染的临床资料进行综合分析 ,采用纸片法 (Kirby- Bauer)测定该菌的体外药物敏感性。结果 :2 8例患者均有基础肺部疾病 ,其中以慢性支气管炎最常见。临床上表现为发热、咳嗽、咳痰 ,脑部 X线表现为双肺淡薄、斑片状阻影。药敏试验表明 ,铜绿假单胞菌对头孢他啶、头孢哌酮耐药率增加。结论 :铜绿假单胞菌下呼吸道感染多发生在患有各种基础疾病 ,尤其是肺部疾病患者 ,临床表现无特异性 ,耐药率有增加趋势。     

应用正交实验研究铜绿假单胞菌原生质体制备与再生

通过对铜绿假单胞菌原生质体制备与再生进行正交实验,探讨各因子对铜绿假单胞菌原生质体制备与再生影响水平,得到铜绿假单胞菌原生质体制备与再生的最优条件:酶解时间 0. 5h,酶浓度 2mg/L,菌龄为 15h 此时原生质体形成率为 80. 5%,再生率为 20. 6%     

铜绿假单胞菌外膜亚蛋白质组图谱的建立

铜绿假单胞菌是人类重要的病原菌,容易造成免疫缺陷患者如烧伤、艾滋病、癌症或囊性纤维化感染,对该菌外膜蛋白的研究有助于了解该菌的致病机制,为进一步疫苗研制奠定基础.采用月桂酰基氨酸钠的方法提取了铜绿假单胞菌的外膜蛋白,首次建立了外膜亚蛋白质组学表达图谱,鉴定了23个外膜蛋白,占所鉴定蛋白的82.1%.然后对其中的一个外膜蛋白基因PA3988进行了克隆及原核表达与纯化,经免疫小鼠获得抗血清后对外膜蛋白进行双向Western blotting分析,验证了质谱的结果.这些研究结果对铜绿假单胞菌外膜蛋白的深入研究具有积极作用.     

Complete genome sequence of Pseudomonas aeruginosa PAO1, an opportunistic pathogen

Pseudomonas aeruginosa is a ubiquitous environmental bacterium that is one of the top three causes of opportunistic human infections. A major factor in its prominence as a pathogen is its intrinsic resistance to antibiotics and disinfectants. Here we report the complete sequence of P. aeruginosa strain PAO1. At 6.3 million base pairs, this is the largest bacterial genome sequenced, and the sequence provides insights into the basis of the versatility and intrinsic drug resistance of P. aeruginosa. Consistent with its larger genome size and environmental adaptability, P. aeruginosa contains the highest proportion of regulatory genes observed for a bacterial genome and a large number of genes involved in the catabolism, transport and efflux of organic compounds as well as four potential chemotaxis systems. We propose that the size and complexity of the P. aeruginosa genome reflect an evolutionary adaptation permitting it to thrive in diverse environments and resist the effects of a variety of antimicrobial substances.     

Pseudomonas biofilm formation and antibiotic resistance are linked to phenotypic variation

Colonization of the lungs of cystic fibrosis (CF) patients by the opportunistic bacterial pathogen Pseudomonas aeruginosa is the principal cause of mortality in CF populations. Pseudomonas aeruginosa infections generally persist despite the use of long-term antibiotic therapy. This has been explained by postulating that P. aeruginosa forms an antibiotic-resistant biofilm consisting of bacterial communities embedded in an exopolysaccharide matrix. Alternatively, it has been proposed that resistant P. aeruginosa variants may be selected in the CF respiratory tract by antimicrobial therapy itself. Here we report that both explanations are correct, and are interrelated. We found that antibiotic-resistant phenotypic variants of P. aeruginosa with enhanced ability to form biofilms arise at high frequency both in vitro and in the lungs of CF patients. We also identified a regulatory protein (PvrR) that controls the conversion between antibiotic-resistant and antibiotic-susceptible forms. Compounds that affect PvrR function could have an important role in the treatment of CF infections.     

Vesicle-related OsSEC27P enhances H<Superscript>+</Superscript> secretion in the iron deficient transgenic tobacco root

Iron is an essential micronutritional element for plants. In addition to the iron uptake mechanism Strategy I and Strategy II, the vesicle transport process was also found to participate in iron uptake and homeostasis. Herein, a new iron deficiency induced OsSEC27P gene was isolated and investigated in both its localization and its function in transgenic plants. The vesicle-related protein OsSEC27P may play a potential role in enhancing H⁺ secretion in roots under the iron deficiency conditions.     

高等植物铁元素的吸收、转位和调控

铁(Fe)是大多数生物体必需的微量营养元素.虽然铁在许多土壤中是丰富的,但铁在土壤中的可溶性非常低,常常限制植物生长.此外,铁自身存在高度的氧化还原特性,对细胞具有潜在的毒性.因此,细胞内铁的动态平衡需要严格调控.植物细胞中形成了一个复杂的信号网络来调节对铁的摄取、分配、运输及其代谢等过程.非禾本科和禾本科植物物种分别通过基于铁还原和铁螯合的两种不同策略从土壤中获得铁.植物对铁的吸收受到局部和全身信号的调控.系统信号通路似乎整合了激素信号、一氧化氮(NO)信号和植物营养需求等多种因素.综述了两种策略所依赖的分子机制和在铁缺乏条件下负责诱导这些策略的因素.     

Iron metabolism in the mononuclear phagocyte system

The maintenance of body iron homeostasis requires the coordination of multiple regulatory mechanisms of iron metabolism. The mononuclear phagocyte system （MPS, composed of monocytes, macrophages, and their precursor cells） is crucial in the maintenance of iron homeostasis. Recycling of iron is carried out by specialized macrophages via engulfment of aged erythrocytes. The iron stores of macrophages depend on the levels of recovered and exported iron. However, the molecular mechanisms underlying iron homeostasis in macrophages are poorly understood. Recent studies characterizing the function and regulation of natural resistance-associated mac- rophage protein 1 （Nrampl）, divalent metal transporter 1 （DMT1）, HLA-linked hemechromatosis gene （HFE）, ferroportin 1 （FPN1）, and hepcidin are rapidly expanding our knowledge on the molecular level of MPS iron handling. These studies are deepening our under- standing about the molecular mechanism of iron homeostasis and iron-related diseases.     

Quorum-sensing signals indicate that cystic fibrosis lungs are infected with bacterial biofilms

The bacterium Pseudomonas aeruginosa permanently colonizes cystic fibrosis lungs despite aggressive antibiotic treatment. This suggests that P. aeruginosa might exist as biofilms--structured communities of bacteria encased in a self-produced polymeric matrix--in the cystic fibrosis lung. Consistent with this hypothesis, microscopy of cystic fibrosis sputum shows that P. aeruginosa are in biofilm-like structures. P. aeruginosa uses extracellular quorum-sensing signals (extracellular chemical signals that cue cell-density-dependent gene expression) to coordinate biofilm formation. Here we found that cystic fibrosis sputum produces the two principal P. aeruginosa quorum-sensing signals; however, the relative abundance of these signals was opposite to that of the standard P. aeruginosa strain PAO1 in laboratory broth culture. When P. aeruginosa sputum isolates were grown in broth, some showed quorum-sensing signal ratios like those of the laboratory strain. When we grew these isolates and PAO1 in a laboratory biofilm model, the signal ratios were like those in cystic fibrosis sputum. Our data support the hypothesis that P. aeruginosa are in a biofilm in cystic fibrosis sputum. Moreover, quorum-sensing signal profiling of specific P. aeruginosa strains may serve as a biomarker in screens to identify agents that interfere with biofilm development.     

微量元素铁对3种水华藻类生长的影响

在温度为25℃,光照强度为2500lx,光暗比为14h∶10h的实验室条件下,研究微量元素铁对3种水华藻类(铜绿微囊藻、小球藻和小环藻)生长的影响.结果表明:当其他营养盐富足时,培养液中的微量元素铁对3种水华藻类的生长均有显著的影响.在培养中期,较高的铁浓度对细胞密度和叶绿素a质量浓度均有明显的促进作用;在培养20d后,当培养液中的铁浓度分别低至0.19~0.24、0.22~0.47和0.15~0.16mg·L~(-1)时,铜绿微囊藻、小球藻和小环藻细胞增殖缓慢.因此,有效调节微量元素铁的浓度也会影响到自然水体中藻类的生长.     

Mitoferrin is essential for erythroid iron assimilation

Iron has a fundamental role in many metabolic processes, including electron transport, deoxyribonucleotide synthesis, oxygen transport and many essential redox reactions involving haemoproteins and Fe-S cluster proteins. Defective iron homeostasis results in either iron deficiency or iron overload. Precise regulation of iron transport in mitochondria is essential for haem biosynthesis, haemoglobin production and Fe-S cluster protein assembly during red cell development. Here we describe a zebrafish mutant, frascati (frs), that shows profound hypochromic anaemia and erythroid maturation arrest owing to defects in mitochondrial iron uptake. Through positional cloning, we show that the gene mutated in the frs mutant is a member of the vertebrate mitochondrial solute carrier family (SLC25) that we call mitoferrin (mfrn). mfrn is highly expressed in fetal and adult haematopoietic tissues of zebrafish and mouse. Erythroblasts generated from murine embryonic stem cells null for Mfrn (also known as Slc25a37) show maturation arrest with severely impaired incorporation of 55Fe into haem. Disruption of the yeast mfrn orthologues, MRS3 and MRS4, causes defects in iron metabolism and mitochondrial Fe-S cluster biogenesis. Murine Mfrn rescues the defects in frs zebrafish, and zebrafish mfrn complements the yeast mutant, indicating that the function of the gene may be highly conserved. Our data show that mfrn functions as the principal mitochondrial iron importer essential for haem biosynthesis in vertebrate erythroblasts.     

细菌铁(Ⅲ)结合蛋白:结构与机理(英文)

铁是生命体必需的微量元素,在大多数环境中铁是有限的资源.高效摄取铁是入侵属主的微生物生存和毒力的关键.许多致病细菌进化出一个特异的铁吸收系统,利用特定的外膜受体和周质铁离子结合蛋白(FBP或FbpA)从属主偷取铁离子.FBP在高效摄取铁的过程中,无论从自由铁源摄取铁或从属主体内转铁蛋白和乳铁蛋白摄取结合的铁,都起着至关重要的作用.FBP的铁结合机制在不同物种间高度保守.结构数据显示,FBP的三维折叠类似于哺乳动物转铁蛋白(TF)的一叶,铁(Ⅲ)在FBP的两个结构域之间的间隙结合但其铁结合位点较其在转铁蛋白中更暴露于溶剂.该小综述总结了FBP铁转运系统,主要讨论了铁结合蛋白的结构和配位化学特征以及铁转运及调控机理.     

铁限制诱导对聚球藻转录组的影响

为探究Fe元素限制对聚球藻转录组的影响,该文以聚球藻Synechococcus sp. PCC 7002为研究对象,采用高通量测序技术对经过铁限制处理的聚球藻Synechococcus sp. PCC 7002进行转录组分析.以铁的3种摩尔浓度进行处理,其中每组数据重复3次实验,一共获得9组实验数据; 对照组摩尔浓度为10.900 nmol·L^-1,铁限制组摩尔浓度分别为0.410、0.003 nmol·L^-1.实验发现:在铁限制环境下,聚球藻通过增加对胞外铁摄取、上调光合作用相关蛋白的表达和调整代谢通路来应对缺铁环境,且铁限制程度与差异基因数量成正相关关系.此外,在强缺铁时通过下调CRISPR系统中某些核酸酶的表达来影响聚球藻抵御外源病毒感染的能力,其转运磷酸基团ABC转运蛋白表达水平下降,从而极大地影响了聚球藻的生存.