猪源肠球菌的分离及生物特性的初报

本研究从猪粪便中分离了肠球菌两珠,经菌种鉴定两珠菌均为屡肠球菌。其生物特性的研究表明：可耐受15的胆盐和6％NaCI高盐,在pH3．0条件下可存活,对绝大多数抗生素耐药。     

炭样小单孢菌JXNU-1广谱抗生素产物的分离及其理化性质

基于实验室自行分离到的一株具有广谱抗菌活性的炭样小单孢菌JXNU-1,研究了该菌株广谱抗生素产物的分离纯化工艺及其部分理化性质.结果表明,该茵产生的抗生素在中性和碱性条件下具有极高的热稳定性,但在酸性条件下不稳定.发酵液通过离心、过滤的预处理过程后,抗生素可吸附到717型阴离子交换树脂上,经2 mol/L的NaCl溶液洗脱除杂,再用20%的乙醇洗脱,可得抗生素产物,且在20%的乙醇溶液中加入2 mol/L的NaCl,可大大提高抗生素的洗脱效率.抗生素的酒精--盐洗脱液经减压浓缩去酒精、透析除盐后可得抗生素的水溶液.该抗生素水溶液经纸层析分析仅检测到单一活性斑点,HPLC分析表明其纯度达到99%以上.所得抗生素在Molish反应,Benedict反应扣二苯胺反应中均呈现阳性,紫外吸收具有典型的核苷类物质的光吸收特征,推测该抗生素为一核苷类抗生素.     

链霉菌M-1菌株所产抑菌活性物质特性的初步研究

用链霉菌M-1菌株所产的抑菌物质进行稳定性试验和极性试验,稳定性试验表明该菌株连续传代10次后遗传性稳定,且发酵液在100℃处理60 min,紫外线照射3 min和在碱性条件下处理后其对病原指示菌的抑菌活性基本不减。极性试验表明该物质属于弱碱性水溶性抗生素。本研究为进一步对该抑菌活性物质分离提取工艺和其在实践上的应用,提供了有益的试验数据。     

抗生素分离纯化技术研究进展

抗生素分离纯化是抗生素产业中的技术难点和关键环节,对抗生素常用的分离纯化技术及其研究进展进行了概述,以期为抗生素分离领域提供理论指导。最后对新型分离纯化技术进行了总结和展望。     

大肠埃希菌对22种抗生素耐药性分析

目的 :研究大肠埃希菌 (EC)对多种抗生素的耐药性。方法 :用 AMS法检测 173株 EC临床菌株的耐药性。结果 :EC对亚胺培南、头孢他啶、头胞噻肟、丁胺卡那霉素的耐药率为 1.2 %～ 3.5 % ,对氨曲南、头孢西丁、呋喃妥因的耐药率为 8.1%～ 10 .4% ,对头孢呋辛钠、头孢呋辛脂、妥布霉素、头孢噻吩的耐药率为 11.6 %～ 19.6 % ,对头孢唑啉、替卡西林 /克拉维酸、环丙沙星、头孢噻吩、庆大霉素、替卡西林和美洛西林的耐药率为 2 7.7%～ 5 9.0 % ,对哌拉西林、四环素、氨苄西林、羧苄西林的耐药率为 6 1.3%～ 76 .9%。在五类标本中 ,不同标本分离的 EC对 1～ 13种抗生素的耐药性差异有显著性 ,P<(0 .0 5 0～ 0 .0 0 5 )。在 2 2种抗生素中 ,15种抗生素对 2～ 6组配对标本分离 EC的敏感性差异有显著性 ,(P<(0 .0 5 0～ 0 .0 0 5 )。结论 :EC对亚胺培南、头孢他啶、头孢噻肟、丁氨卡那霉素的耐药率低 ,对羧苄西林、氨苄西林、四环素、哌拉西林的耐药率高 ,不同标本分离 EC对多种抗生素的耐药性差异有显著性。     

褐变蚕蛹分离蛋白脱色与改性研究

研究了褐变蚕蛹分离蛋白脱色方法及其酸酐、硫酸锆改性。用酸性乙酸酐法处理蚕蛹分离蛋白质 ,可获得白色脱色物 ,其最佳条件是 ,蚕蛹分离蛋白∶乙酸酐∶H2 O2 =1∶1.2 5∶1.5、温度≥ 80℃、时间≥ 30min。过氧乙酸的作用可能是使参与褐变的赖氨酸ε 氨基重新游离并断开胱氨酸之间的二硫键。乙酸酐或顺丁烯二酸酐修饰赖氨酸ε 氨基的最适条件是 :脱色蛋白∶乙酸酐 (或顺丁烯二酸酐 ) =1∶0 .3(或 0 4 )、pH 9.0～ 9.5、温度≤ 4 5℃、时间 6 0min。硫酸锆修饰氨基和羧基的最适条件是 :脱色蛋白∶硫酸锆 =1∶0 .0 4、pH≤ 3.0、温度≥ 80℃、时间 10min。脱色蛋白经过乙酸酐或顺丁烯二酸酐、硫酸锆修饰 ,其白色可稳定 ,在pH 2～ 12及 80℃条件下均不变色。在碱性条件下 ,H2 O2 可部分氧化蚕蛹分离蛋白褐色 ,获得乳黄色脱色物 ,其最适条件是 ,蚕蛹蛋白∶H2 O2 =1∶1.5、pH 9.0～ 9.5、温度≥ 80℃、时间≥30min。蚕蛹蛋白褐变的原因可能主要是其赖氨酸ε 氨基与氨基葡萄糖在碱性加热条件下发生Marl laid反应所致。此外 ,蛋白质中游离α 氨基、谷氨酸γ 羧基及天门冬氨酸β 羧基可能也参与了褐变反应     

辽宁西部丘陵山区土壤微生物调查

为了调查和利用我省土壤微生物资源,寻求新的农业抗生素,我们从北票市大黑山和朝阳市凤凰山主峰周围共采集土壤样品83份;对其中好氧微生物进行了分离测定。初步探明了不同海拔高度、不同植被土壤环境条件下,微生物类群的分布     

拮抗放线菌Y-71的鉴定及其代谢活性物质的性质

本研究从云南采集的腐质土壤样品中分离筛选到一株拮抗放线菌Y-71,通过形态特征、培养特征、生理生化特征、细胞化学组分和基于16SrRNA基因序列的相似性分析等研究,鉴定菌株Y-71为脱叶链霉菌(Streptomyces exfoliatus)。抗菌谱测定及稳定性研究结果表明,菌株Y-71发酵液抑菌谱较广,对革兰氏阳性细菌和革兰氏阴性细菌都有较好的抑制作用;其抑菌活性物质对温度敏感,在70°C处理后抑菌活性丧失;在pH2-8条件下稳定;不能被蛋白酶降解,可初步判定此活性物质不属于蛋白质或肽类物质。本研究为该菌株今后的应用、抗生素的分离提纯奠定了基础。     

长效益生素菌株的筛选及生产工艺的初步研究

益生素是一种能够替代抗生素的绿色饲料添加剂。报道了通过对益生素菌种的初筛和复筛、菌株药敏实验、菌体吸附方法及产品的中试研究 ,确定了生产工艺 :采用筛选的地衣芽孢杆菌YS 0 2 ,在特定的培养基和培养条件下 18～ 2 2h ,通过 10 %CaCO3 吸附、过滤、干燥获得微生态制剂 ,其活菌数≥ 15 0亿 / g。实验证明 ,YS 0 2活菌制剂可替代抗生素防治动物习惯性腹泻。     

外排泵抑制剂对阴沟肠杆菌耐药表型影响

目的探讨主动外排泵在临床分离阴沟肠杆菌多重耐药的作用。方法收集、分离及鉴定阴沟肠杆菌,采用琼脂稀释法测定多重耐药泵抑制剂氰氯苯腙(carbonyl cyanldem-chlorophenylhydrazone,CCCP)应用前后,阴沟肠杆菌对头孢他啶、阿米卡星、阿奇霉素、左氧氟沙星和四环素5种抗生素的最小抑菌浓度(MIC)的变化。结果以上述5种抗生素为底物8,3株阴沟肠杆菌中,分别有303、61、9、32和28株在10μg/mL CCCP条件下MIC值降低4倍或4倍以上,其中有19株同时对3种及以上抗生素有明显外排作用。外排泵存在于耐药株和非耐药株中,但对耐药株的影响较大。结论主动外排系统广泛存在于临床分离阴沟肠杆菌中,是引起阴沟肠杆菌多重耐药的重要机制。外排泵抑制剂CCCP可增加阴沟肠杆菌对抗菌药物的敏感性。     

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.