基于高通量解析和可培养技术的白蔹内生真菌类群分析及分离菌株的抗痤疮致病菌活性

【背景】药用植物蕴含丰富的内生真菌类群资源,而且内生真菌可产生与宿主相关的次级代谢产物,具有多种生物活性,是活性化合物生产的潜在经济来源。【目的】分析药用植物白蔹根部内生真菌的物种多样性,并筛选出具有抗痤疮致病菌活性的目标菌株。【方法】基于高通量和组织分离法分析白蔹内生真菌的类群结构多样性;通过琼脂扩散法对内生真菌代谢产物的抗痤疮致病菌活性进行筛选;以微量肉汤稀释法测定代谢产物的最小抑菌浓度(minimuminhibitory concentration, MIC)和最小杀菌浓度(minimum bactericidal concentration, MBC)。【结果】高通量测序结果显示,白蔹根部内生真菌可注释到8门22纲45目73科93属,根部的优势属为Tainosphaeria(20.86%)和镰刀菌属(Fusarium, 15.38%)。基于组织分离法共从白蔹根部分离获得83株内生真菌,隶属于12个属,其中青霉属(Penicillium,24.10%)、木霉属(Trichoderma,14.46%)、背芽突霉属(Cadophora, 13.25%)、镰刀菌属(Fusarium, ...     

纳米银的抗菌特性及对多重耐药菌株的抗菌作用

【目的】利用革兰氏阴性细菌、革兰氏阳性细菌和真菌的模式菌株分析纳米银的抗菌特性,并评价纳米银对多重耐药菌株的抗菌作用。【方法】利用生物法合成的纳米银,以微量肉汤法测定3种标准菌株的最小抑菌浓度(MIC)和最小杀菌浓度(MBC),并计算MBC/MIC比值。用系列浓度的纳米银处理3株标准菌株后经平板计数法绘制时间-杀菌曲线。采用菌落平板计数法测定了纳米银对3种标准菌株的"抗生素后效应"(post-antibiotic effect,PAE),最后在生物安全II级实验室测定纳米银对临床分离的多重耐药菌株的抗菌作用。【结果】用生物法合成了粒径5–30 nm的纳米银,zeta电位为–19.5 m V。该纳米银制剂对3种标准菌株的时间-杀菌曲线均表现为时间依赖型抗菌作用。纳米银对大肠杆菌和白色念珠菌"抗生素后效应"随着浓度增加而增加,对金黄色葡萄球菌无明显"抗生素后效应"。纳米银对3种标准菌株的MIC值和MBC值均在1.00–4.00μg/m L之间;对3株人源性多重耐药菌MIC值在6.00–26.00μg/m L之间,MBC值在1.00–32.00μg/m L之间;对14株动物源性多重耐药菌MIC值在4.00–10.00μg/m L之间,MBC值在8.00–16.00μg/m L之间。纳米银对所有测试菌株的MBC/MIC值均小于2。【结论】纳米银是一种时间依赖型的抗菌剂,有不同程度的"抗生素后效应",对人源和动物源性多重耐药菌有杀菌作用。     

蒺藜内生真菌发酵液抗菌及抗肿瘤活性初步研究

【目的】筛选出具有抗菌和抗肿瘤活性的蒺藜内生真菌。【方法】采用牛津杯法、稻瘟菌模型及肿瘤细胞模型评价蒺藜内生真菌PDB和察氏培养基发酵产物的抗菌活性和肿瘤细胞毒性。【结果】PDB培养基发酵液和察氏培养基发酵液抑菌圈直径大于10 mm的菌株分别占总菌株数的19.05%和23.81%。PDB培养基发酵液和察氏培养基发酵液对稻瘟菌的最小抑制浓度(MIC)低于10%的菌株分别占总菌株数的19.05%和47.61%。对肿瘤细胞抑制率高于50%的PDB发酵产物占PDB发酵产物总数的52.38%, 而对肿瘤细胞抑制率高于50%的察氏发酵产物占察氏发酵产物总数的28.57%。【结论】部分蒺藜内生真菌的发酵产物具有抗菌和抗肿瘤活性。     

枯草芽孢杆菌中bacilosarcin B对美人鱼发光杆菌的抑菌机理

【背景】美人鱼发光杆菌(Photobacteriumdamselae)是一种海洋条件致病菌,能够引起多种海洋生物和人类疾病。因此,探究美人鱼发光杆菌的生物防治技术具有重要意义。【目的】探究枯草芽孢杆菌(Bacillus subtilis)中bacilosarcin B对美人鱼发光杆菌的抑菌活性及其可能的抑菌机理。【方法】利用高效液相色谱法从枯草芽孢杆菌fmb60发酵液中制备bacilosarcin B,采用分光光度法测定bacilosarcinB对多种致病菌的最小抑菌浓度及其对美人鱼发光杆菌的时间-抑菌曲线。测定bacilosarcin B对美人鱼发光杆菌生物被膜、胞外核酸、蛋白质和胞内碱性磷酸酶含量的影响,结合荧光显微镜、扫描电镜和透射电镜检测美人鱼发光杆菌细胞膜通透性和细胞壁完整性,并研究bacilosarcin B对细菌运动能力和胞内DNA的作用。【结果】Bacilosarcin B对美人鱼发光杆菌最小抑菌浓度为8μg/mL。抑菌机理研究表明bacilosarcin B通过破坏细菌细胞壁和细胞膜的完整性使细胞膜通透性增强,造成细胞内成分渗出。此外,bacilosarcinB还可与...     

生姜精油化学成分及其抗菌活性

【背景】随着耐药微生物种类的增多和耐药性增强,抗耐药微生物新药的发现已成为全球关注的问题。生姜精油是纯天然植物精油,是天然抗菌材料的优选。【目的】分析生姜精油的化学成分,研究生姜精油对常见条件致病菌抗菌活性的影响,并阐明其可能的抗菌机制。【方法】采用气相色谱/质谱技术(Gas Chromatography/Mass Spectrometry,GC/MS)对生姜精油的化学成分进行分析,利用牛津杯法、最小抑菌浓度法(Minimum Inhibitory Concentration,MIC)、最小杀菌浓度法(Minimum Bactericidal Concentration,MBC)和生长曲线绘制法研究生姜精油的抗菌活性和抗菌动力学特征,并通过透射电镜(Transmission Electron Microscopy,TEM)观察生姜精油对细菌超微结构的影响。【结果】生姜精油的化学成分主要为姜烯(22.014%)、β-倍半水芹烯(11.276%)、α-法呢烯(8.222%)、α-姜黄烯(6.854%)、姜酮(5.610%)、姜辣二酮(5.192%)、6-姜烯酚(4.670%)、桧烯(3.393%)和β-红没药烯(3.080%)等萜类物质。生姜精油对枯草芽孢杆菌的MIC和MBC分别为2.3μg/mL和4.6μg/mL;对表皮葡萄球菌及金黄色葡萄球菌的MIC均为9.2μg/mL,MBC均为18.4μg/mL;对肺炎克雷伯菌的MIC和MBC分别为18.4μg/m L和36.8μg/mL。生长曲线结果显示,生姜精油能延长细菌的生长停滞期、抑制细菌的生长速率。透射电镜结果表明,生姜精油能引起细菌细胞膜破损,致使胞内物质渗漏。【结论】生姜精油富含萜类化合物,具有中度的抗菌活性,能破坏细菌细胞膜的完整性,引起菌体损伤和死亡。本文有望更好地为有害微生物的防控提供新方法。     

复合生物保鲜剂对松鼠葡萄球菌的抑菌性能及其作用机理研究

以冷藏带鱼中分离出的革兰氏阳性优势菌——松鼠葡萄球菌(Staphylococcus sciuri)为试验菌,研究复合生物保鲜剂(配比浓度为:壳聚糖10.0 g/L,溶菌酶0.3 g/L与茶多酚3.0 g/L)对松鼠葡萄球菌的抑菌效果与作用机理。通过牛津杯法确定复合保鲜剂对松鼠葡萄球菌的最小抑菌浓度(MIC)与最小杀菌浓度(MBC),结合抑菌活力、细菌生长曲线、碱性磷酸酶(AKP)活性、细胞膜完整性、膜通透性与细菌超微结构观察等,综合评价不同浓度复合保鲜剂在不同处理时间内对松鼠葡萄球菌的作用效果。结果表明,复合保鲜剂对松鼠葡萄球菌的MIC与MBC分别为0.8与1.6 mg/mL,随着处理时间的延长,复合生物保鲜剂明显抑制松鼠葡萄球菌的生长,使菌体细胞外的AKP量增多,造成细菌菌体细胞壁通透性增大,细胞结构的完整性受到破坏,菌液电导率值显著升高,菌体电解质等内容物外泄,影响细胞内环境和细胞膜的稳定性,菌体皱缩变形,表面粗糙,细胞壁塌陷,细胞质外泄渗出,导致菌体死亡。     

蓝莓提取物对产超广谱β-内酰胺酶肺炎克雷伯菌的抑菌活性

【背景】随着细菌耐药性的增强,产超广谱β-内酰胺酶肺炎克雷伯菌的出现严重危害食品安全和人体健康。蓝莓中含有丰富的多酚和花青素,是天然抗菌材料的优选。【目的】分析蓝莓提取物对3株产超广谱β-内酰胺酶肺炎克雷伯菌的抑制活性及作用机制,并以牛乳为样品检测食品基质对蓝莓提取物抑菌活性的影响。【方法】利用甲醇制备巴尔德温和黑珍珠蓝莓提取物并检测提取物中总酚和花青素含量,利用纸片扩散法检测肺炎克雷伯菌的耐药性,利用最小抑菌浓度(minimum inhibitory concentration,MIC)、最小杀菌浓度(minimum bactericidal concentration,MBC)和生长曲线研究蓝莓提取物的抗菌活性,通过共聚焦激光扫描显微镜观察蓝莓提取物对细胞膜完整性的影响,并检测其在牛乳中的抑菌活性。【结果】巴尔德温和黑珍珠蓝莓提取物中的总酚含量分别为2.3 mg/g和3.5 mg/g,花青素含量分别为67.5 mg/100 g和92.5 mg/100 g。两种蓝莓提取物对肺炎克雷伯菌KP106、KP305和KP408的MIC均为25mg/mL,MBC均为50mg/mL。生长曲线表明...     

海洋芽孢杆菌（Bacillus marinus）B-9987菌株抑制病原真菌机理的研究

摘要：【目的】：探讨海洋芽孢杆菌（Bacillus marinus）B-9987菌株的代谢产物BMME-1,对植物病原真菌茄链格孢菌的抑菌作用机理。【方法】分别使用分光光法、气相色谱-质谱GC-MS联用技术、红外光谱法等,检测了BMME-1处理病原真菌后,菌体渗透性、细胞壁及细胞膜成份的变化。【结果】BMME-1对茄链格孢菌的抑菌中浓度（MIC50）为6.2 mg/L,最小杀菌浓度（MFC）为50 mg/L,在MIC50浓度或高于此浓度处理靶标菌,将导致菌体蛋白质、核酸等大分子物质的外流;处理菌株葡聚糖结     

链霉菌H03发酵液提取物的抗菌活性研究

以常见的病原细菌和植物病原真菌为指示菌研究了链霉菌发酵液提取物的抗菌活性,测定了发酵液提取物的抗菌谱和最小抑菌浓度(MIC)。结果表明:与青霉素、链霉素相比,该菌发酵液提取物的抗菌范围更广,对植物病原真菌棉花黄萎病菌、苹果轮纹病菌、小麦赤霉病菌、油菜菌核病菌、黄瓜炭疽病菌、甜菜褐斑病菌、稻瘟病菌,以及常见病原细菌大肠杆菌、枯草杆菌、绿脓杆菌和金黄色葡萄球菌都具有明显的抑制作用。利用试管二倍稀释法测定发酵液提取物对上述诸菌的最小抑菌浓度(MIC),结果分别为0.125、0.062 5、0.125、0.25、0.015、0.03、0.015、0.015、0.03、0.250、.015 mg/mL。其中对植物病原真菌中的黄瓜炭疽病菌、甜菜褐斑病菌、稻瘟病菌,以及病原细菌中的大肠杆菌、枯草杆菌、金黄色葡萄球菌抑制效果最佳。将发酵液提取物置于100℃下加热处理10 min后,其对金黄色葡萄球菌的抑菌活性不变,说明该发酵液提取物具有较好的热稳定性。     

香芹酚联合头孢曲松对耐药性沙门氏菌的体外抗菌作

【背景】由于抗生素的滥用,使得细菌耐药性问题严峻,寻找解决耐药性细菌感染的治疗策略迫在眉睫。临床上,中药与抗菌药物联用在抗耐药性细菌感染方面效果显著。【目的】研究香芹酚联合头孢曲松对耐药性沙门氏菌(SJ2)的协同效应及机制。【方法】通过二倍肉汤稀释法测定香芹酚和头孢曲松对SJ2的最小抑菌浓度(minimal inhibitory concentration, MIC);通过棋盘法和生长曲线测定探究香芹酚和头孢曲松联合抗SJ2活性;通过膜电位检测、胞外碱性磷酸酶(alkaline phosphatase, AKP)含量测定、菌体内抗生素蓄积分析、细菌生存活力测定及扫描电镜研究香芹酚联合头孢曲松对SJ2细胞壁、细胞膜的影响。【结果】香芹酚和头孢曲松对SJ2的MIC分别为256μg/mL和2 048μg/mL;香芹酚联合头孢曲松对SJ2具有协同作用,其分级抑制浓度指数(fractional inhibitory concentration index, FICI)为0.375;香芹酚可协同头孢曲松使SJ2细胞膜出现去极化,显著增加AKP泄漏至胞外的量(P<0.05),显著增加菌体胞内抗...     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.