5.0%与1.0%葡萄糖环境中变形链球菌差异表达基因的检测

目的:观察高浓度葡萄糖营养条件对变形链球菌基因表达的影响。方法:变形链球菌分别在5.0%、1.0%葡萄糖条件下培养,利用前期构建的变形链球菌基因表达谱检测芯片筛选两种培养条件下变形链球菌中差异表达的基因,以观察高浓度葡萄糖对变形链球菌基因表达的影响。结果:相对于1.0%葡萄糖,在5.0%葡萄糖条件下变形链球菌中有约54种基因表达发生显著变化,其中与变形链球菌糖转运系统和能量代谢、DNA代谢、氨基酸代谢、细胞生理过程、信号传递与调控系统、粘附等细菌毒力等相关的44种基因表达明显上调,而一些感受态蛋白和参与信号传递与调控的10种基因表达显著下调(P相似文献   

变形链球菌磷酸转移酶在不同蔗糖浓度下的差异性表达

目的 检测变形链球菌不同毒力株的致龋性与磷酸转移酶(pts)系统各编码基因表达变化的关系.方法 选取高毒力株临床分离株502与低毒力株标准株UA159,以real-time PCR方法检测在1%和2%蔗糖浓度下,变形链球菌磷酸转移酶系统各编码基因的表达变化.结果 1%蔗糖浓度,高毒力株和低毒力株的scrA、scrB、p...     

变形链球菌gtfs在不同蔗糖浓度下的差异性表达

目的 检测具有不同产细胞外多糖能力的变形链球菌株,在不同培养条件下产细胞外多糖的能力及与gtfA、B、C、D表达变化的关系.方法 选取变形链球菌高产糖与低产糖的临床分离菌株各10株及标准菌株UA159,用蒽酮法分别检测在1％、2％蔗糖培养下产细胞外多糖的能力;再用real-time PCR方法检测这些条件下与变链产糖...     

基因芯片技术在变形链球菌分子生物学研究中的应用

基因芯片技术是近年来的一种新兴的分子生物学研究工具,用来分析基因的突变、多态性以及测序等;变形链球菌是人类主要致龋菌,定量检测和鉴别变形链球菌的种属类型和它们的相互关系,对龋病的防治具有重要意义.本文就基因芯片技术在口腔变形链球菌研究中的应用作一综述.     

在不同浓度蔗糖条件下变形链球菌对镍铬合金腐蚀性能的影响

目的 探讨不同浓度的蔗糖条件下,变形链球菌与镍铬合金共同培养后,合金耐蚀性能受到的影响。方法 将镍铬合金制作12个试件,随机分为5.0%蔗糖实验组、5.0%蔗糖培养基对照组、1.0%蔗糖实验组及1.0%蔗糖培养基对照组。8周后分别取出做电化学实验和扫描电镜实验进行耐腐蚀性能的研究。结果 电化学实验结果显示:5.0%蔗糖实验组与1.0%蔗糖实验组相比,自腐蚀电位与自腐蚀电流密度差异均不显著;5.0%蔗糖培养基对照组与1.0%蔗糖培养基对照组相比,自腐蚀电位绝对值减小,自腐蚀电流密度减小(差异均有统计学意义)。扫描电镜实验结果显示:两实验组试件表面无明显差别,与1.0%蔗糖培养基对照组比较,5.0%蔗糖培养基对照组表面出现斑块状花纹,无明显腐蚀痕迹。结论 蔗糖浓度的增加对变形链球菌的生长繁殖有利,但未必会增强变形链球菌对镍铬合金表面腐蚀性的影响。     

变形链球菌表面蛋白PAc不同表达株的蔗糖粘附实验

研究变形链球菌表面蛋白ＰＡｃ没表达株在含蔗糖培养基中，及加氟至１ｐｐｍ或洗必地０．００５％的含蔗培养基中对玻壁表面粘附能力的差异。方法 在厌氧培养条件下培养各株变形链球菌，用ＯＤ值测量法计算粘附量。结果 在普通 入氟至１ｐｐｍ的含蔗糖培养基中，变链菌表面蛋白ＰＡｃ没表达株对玻壁的粘附无差异。     

蔗糖浓度对变形链球菌wapA基因表达的影响

目的:观察不同浓度蔗糖环境对变形链球菌粘附相关基因wapA表达的影响.方法:变形链球菌分别在0.5%、1%、5%蔗糖条件下培养,提取总RNA,逆转录成cDNA,利用TaqMan实时荧光定量PCR技术检测不同环境条件下变形链球菌粘附相关基因wapA的表达.结果:不同浓度蔗糖条件下变形链球菌wapA基因表达的变化不具有统计学意义;0.5%和5%蔗糖条件下,粘附较强的菌株其wapA基因的表达明显高于粘附较弱的菌株.结论:蔗糖量的增加对变形链球菌wapA基因表达的影响不大;wapA基因表达的量可能与变形链球菌的蔗糖依赖性粘附呈正相关关系.     

变形链球菌检测技术新进展

变形链球菌是目前公认的最重要的致龋菌,在龋风险评价中有重要意义。笔者从微生物学方法、分子生物学方法、免疫学方法、生物芯片技术、代谢组学方法等方面对变形链球菌的检测技术作一综述。     

变形链球菌临床株F-ATPase亚基基因uncEBF在mRNA水平的表达

目的:研究变形链球菌临床分离株耐酸因子F-ATPase c、a、b亚基联合基因uncEBF在mRNA水平的表达差异,探讨基因表达水平与细菌耐酸力以及uncEBF基因型的关系。方法:应用半定量RT-PCR两步法和凝胶成像系统定量软件分析,分别对18株来自不同基因型和不同耐酸力变链菌的uncEBF基因表达水平进行评价,以SPSS11.0软件分析和比较mRNA表达的差异。结果:不同基因型及不同耐酸力菌株un-cEBF的mRNA表达水平不同(P<0.05),表现为A基因型uncEBF表达高于B基因型,高耐酸力菌株un-cEBF表达高于低耐酸力菌株。结论:变链菌不同基因型uncEBF基因的表达水平不同,表达水平高低与菌株的耐酸力相关。     

聚合酶链反应检测致龋性变形链球菌

本研究旨在应用聚合酶链反应检测致龋性变形链球菌。针对血清C型变形链球菌的spaP基因序列合成特异性引物,用聚合酶链反应(PCR)扩增spaP基因片段的方法检测变形链球菌各菌株和口腔多种常居菌。结果只有变形链球菌血清C型产生了扩增产物,呈现单一的192bpDNA条带。这种方法使过去不能检出的微量靶序列(3个cfu)得以检出,具有高度的特异性和敏感性。用本方法检测50例口腔菌斑标本,有44例呈阳性结果。提示该检测技术是一种快速、准确检测变形链球菌的新方法。     

定量聚合酶链反应检测致龋性变形链球菌

目的 创建一种临床定量检测致龋性变形链球菌的分子生物学方法。方法 采用靶基因与参照基因同步扩增法，根据变形链球菌葡聚糖酶（dexA)基因序列，设计一对特异性引物，以pET23b质粒DNA为参照基因。对196名儿童的唾液样品进行定量PCR检测并进行常规培养法的对比研究。结果 196份唾液样品定量PCR检测致龋性变形链球菌≥10^8CFU/L，唾液的检出率为91.3%。与常规培养计量法的对比符合率为94.9%。结论 变形链球菌PCR定量检测是一种早期发现龋病活性的新方法，具有快速可靠、特异性强、符合率高等特点，有广泛的临床应用前景。     

Detection of serotype k Streptococcus mutans in Thai subjects

Introduction:  Streptococcus mutans , known to be a pathogen of dental caries as well as bacteremia and infective endocarditis, is classified into four serotypes, c , e , f and k , based on the structures of serotype-specific polysaccharides. Serotype k was recently designated using blood isolates from Japanese subjects and such strains are considered to be virulent in the bloodstream. The purpose of the present study was to analyse the serotype distribution of strains isolated from Thai subjects and determine whether serotype k strains were present.
Methods:  A total of 250 S. mutans strains were isolated from 50 Thai subjects, and serotypes of all strains were determined. Then, molecular and biological analyses were carried out for serotype k strains.
Results:  Immunodiffusion and polymerase chain reaction analyses showed that serotype c was the most prevalent (70%), followed by serotypes e (22.8%), f (4.4%) and k (2.8%), which indicated that serotype k S. mutans strains occurred in Thai individuals at a similar rate to that previously reported for Japanese and Finnish populations. Molecular analyses of the seven serotype k strains showed extremely low expression of rgpE , which is related to glucose side-chain formation in serotype-specific rhamnose-glucose polymers, similar to previous reports for those other populations. In addition, analysis of the biological properties of the seven serotype k strains demonstrated low levels of sucrose-dependent adhesion, cellular hydrophobicity, dextran-binding activity and phagocytosis susceptibility by human polymorphonuclear leukocytes, which are characteristics similar to those of serotype k strains previously isolated in Japan.
Conclusion:  Our results indicate the possibility of a worldwide prevalence of serotype k strains with properties in common with those of previously reported strains.     

pH regulation by Streptococcus mutans.

The intracellular pH (pHi) optimum for glycolysis in Streptococcus mutans Ingbritt was determined to be 7.0 by use of the ionophore gramicidin for manipulation of pHi. Glycolytic activity decreased to zero as the pHi was lowered from 7.0 to 5.0. In contrast, glycolysis had an extracellular pH (pHo) optimum of 6.0 with a much broader profile. The relative insensitivity of glycolysis to the lowering of pHo was attributed to the ability of S. mutans to maintain a transmembrane pH gradient (delta pH, inside more alkaline) at low pHo. At a pHo of 5.0, glycolyzing cells of S. mutans maintained a delta pH of 1.37 +/- 0.09 units. The maintenance of this delta pH was dependent on the concentration of potassium ions in the extracellular medium. Potassium was rapidly taken up by glycolyzing cells of S. mutans at a rate of 70 nmol/mg dry weight/min. This uptake was dependent on the presence of both ATP and a proton motive-force (delta p). The addition of N-N'-dicyclohexylcarbodiimide (DCCD) to glycolyzing cells of S. mutans caused a partial collapse of the delta pH. Growth of S. mutants at pHo 5.5 in continuous culture resulted in the maintenance of a delta pH larger than that produced by cells grown at pH 7.0. These results suggest the presence of a proton-translocating F1Fo-ATPase in S. mutans whose activity is regulated by the intracellular pH and transmembrane electrical potential (delta psi). The production of an artificial delta p of 124 mV across the cell membrane of S. mutans did not result in proton movement through the F1Fo-ATPase coupled to ATP synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)