Development of a multifunctional and efficient conjugal plasmid for use in Streptomyces spp

A plasmid, pGB112, has recently been developed to transfer DNA from Escherichia coli to Streptomyces spp via conjugation. This technique made use of (A) E. coli replicon, (B) ampicillin (amp) resistance gene for selection in E. coli and thiostrepton (tsr) resistance gene for selection in Streptomyces, (C) a fragment of SCP2* replicon, (D) a 2.6 kb fragment of tra-cassette which consists of pIJ101 transfer gene (tra) and two ermE promoters, (E) a 0.8 kb fragment of oriT of (IncP) RK2. The results showed that this plasmid was able to transfer plasmid DNA from E. coli to Streptomyces coelicolor via conjugation, and that it could also transfer DNA between Streptomyces strains. Since this plasmid has both pBR322 and SCP2* replicons, it may provide a novel and useful method for genetic operation in E. coli and Streptomyces.An erratum to this article can be found at     

Reactive oxygen metabolism in mycorrhizal and non-mycorrhizal citrus (Poncirus trifoliata) seedlings subjected to water stress

The effect of the arbuscular mycorrhizal (AM) fungus, Glomus versiforme, on growth and reactive oxygen metabolism of trifoliate orange (Poncirus trifoliata) seedlings was studied in potted plants under well-watered (WW) and water stressed (WS) conditions. Water stress significantly decreased root colonization. Shoot dry weight, plant height and stem diameter were higher in AM than in non-AM seedlings regardless of the water status. Inoculation with G. versiforme increased root dry weight and leaf number per plant of WW seedlings. There was less malondialdehyde (MDA) concentration in leaves and roots of AM seedlings, as well as lower hydrogen peroxide (H(2)O(2)) and superoxide anion radical (O(2)(-)) concentrations in AM roots under WW and WS conditions. AM inoculation did not affect the H(2)O(2) and O(2)(-) concentrations of WW leaves. Whether WS or not, AM symbiosis notably increased the guaiacol peroxidase (G-POD) activity of leaves, glutathione reductase (GR) activity of leaves and ascorbate peroxidase (APX) activity of roots. AM infection also markedly increased the APX activity of WS leaves. Soluble proteins and glutathione (GSH) in leaves and roots and ascorbate (ASC) in leaves were higher in WW AM than in WW non-AM seedlings. AM infection also enhanced the ASC and GSH contents of leaves and roots in WS seedlings. Cross-tolerance might occur in AM plants and be enhanced by AM symbiosis. Our results suggest that the increased concentrations of antioxidant enzymes and non-enzymatic antioxidants found in AM plants may serve to protect the organism against oxidative damage, enhancing drought tolerance.     

Global human genetics of HIV-1 infection and China

Genetic polymorphisms in human genes can influence the risk for HIV-1 infection and disease progression, although the reported effects of these alleles have been inconsistent. This review highlights the recent discoveries on global and Chinese genetic polymorphisms and their association with HIV-1 transmission and disease progression.     

Effects of drug relief hospital-based AIDS educational methods on drug users

INTRODUCTION Today, Acquired Immunodeficiency Syndrome (AIDS) has become a public health and social problem that has caused significant harm to the survival and development of humanbeings. Route of transmission of Human Im- munodeficiency Virus (HIV) is still predominantly through shared syringes by drug abusers. Currently, there is no efficient medicine, treatment or educational method to prevent HIV transmission in China. Intervention is prob- ably the best “vaccine” [1]. Despi…     

上海城市公共开放空间夏季小气候及舒适度

基于2006年5—8月上海城区5种类型公共开放空间（广场、喷泉、草坪、廊道、林地）的空气温度、相对湿度、风速和辐射强度等小气候指标,分析了各空间类型对小气候的调节作用,并采用体感气象指数（discomfort index, DI）作为评价指标,比较了各空间类型对人体舒适程度影响的差异.结果表明：上海市5种类型公共开放空间的平均温度、相对湿度等小气候因子存在一定差异;平均气温依次为广场＞草坪＞喷泉＞廊道＞林地;平均空气相对湿度依次为林地＞廊道＞喷泉＞草坪＞广场;广场面积、喷泉水体附近的风速及风向、草坪的草种类型、廊道的宽度及乔木盖度、林地的盖度及乔木林冠层高度等非气候指标分别与各自空间的气候指标呈显著相关.与其他3种空间类型相比,林地和廊道具有明显的遮荫、降温、增湿作用,对小气候的调节能力更佳.     

外阴阴道假丝酵母菌病的阴道清洁度观察

目的观察外阴阴道假丝酵母菌病阴道清洁度的情况。方法用湿片法进行阴道分泌物检查,随机选取1000例念珠菌阳性分泌物,对其阴道清洁度进行观察。结果1000例念珠菌阳性分泌物中,阴道清洁度Ⅳ度有606例,阴道清洁度Ⅲ度有279例,阴道清洁度Ⅱ度有82例,阴道清洁度Ⅰ度有33例。结论虽然大多数念珠菌阳性分泌物（88．5％）阴道清洁度异常（Ⅲ～Ⅳ度）,但仍然有少数念珠菌阳性分泌物（11．5％）阴道清洁度属于正常（Ⅰ～Ⅱ度）。这一结果应有助于临床妇产科医生在为患者做常规妇检、在外观性状上对阴道分泌物作判断时采取更加谨慎的态度。     

NOS抑制剂对CLP败血症休克大鼠血流动力学及血管张力变化的影响

目的:探讨三种一氧化氮合酶抑制剂(NOSI)对盲肠结扎和穿孔法(CLP)败血症休克血流动力学改变及血管张力变化的影响.方法:采用CLP建立大鼠败血症休克模型,腹腔注射三种NOSI对CLP败血症休克进行干预;在体颈动脉插管和心室内导管术,测定血压和左心室动力学指标;用离体血管灌流方法,测定大鼠胸主动脉环的张力.结果:分别用三种NOSI可降低CLP败血症休克的死亡率,改善血压和左心室动力学指标;三种NOSI均能抑制CLP引起的去内皮主动脉环对苯肾上腺素(PE)和KCl的收缩反应性下降,并且iNOSI氨基胍(AMG)能够抑制CLP引起的去内皮主动脉环对细胞外钙的反应性降低;非选择性NOSI左旋硝基精氨酸甲酯(L-NAME)与nNOSI7-硝基吲唑(7-NI)均能抑制CLP引起的内皮完整主动脉环对苯肾上腺素(PE)和KCl的收缩反应性下降,但是三种NOSI均不能抑制CLP引起的内皮完整动脉环对细胞外钙的反应性降低.结论:三种NOSI均能改善CLP晚期败血症休克大鼠血流动力学和无内皮血管的收缩反应性,L-NAME和7-NI还可改善有内皮血管的收缩反应性.     

银杏苦内酯B对重症急性胰腺炎大鼠血浆中白介素12和血小板活化因子的影响

目的：观察重症急性胰腺炎（SAP）大鼠血浆白介素12（IL-12）、血小板活化因子（PAF）的水平变化,探讨银杏苦内酯B（BN52021）对SAP的治疗作用。方法：Wistar大鼠随机分成SAP模型组（SAP）、BN52021治疗组（BN）和阴性对照组（NC）。前两组以5%牛磺胆酸钠逆行注入主胰管制成SAP模型,NC组仅翻动十二指肠并触摸胰腺数次关腹,制模15 min后,SAP组、NC组经股静脉注射生理盐水,BN组以BN52021静注 应用ELISA技术测定血浆IL-12和PAF水平。结果：各组血浆IL-12水平存在明显差异,BN组在1 h时相点较SAP、NC组显著性升高（P〈0.01） SAP组在6 h1、2 h时相点较NC组显著性升高（P〈0.01,P〈0.05）。各组血浆PAF水平存在明显差异,在1 h时相点,SAP组与BN组PAF含量较NC组均显著升高（P〈0.01） 在6 h、12 h时相点,SAP组PAF含量显著高于NC组、BN组（P〈0.05,P〈0.01）。结论：SAP大鼠早期血浆IL-12水平降低,PAF水平显著升高 BN52021对SAP大鼠具有一定的治疗作用,使早期血浆IL-12水平升高,PAF水平下降。     

神经球结合异种细胞生长的实验研究

目的 研究神经球在形成过程中是否能结合异种细胞,并与之形成杂合细胞球.方法 分别用绿色荧光蛋白(EGFP)标记的神经球来源细胞、大鼠神经胶质瘤细胞C6、HER293细胞,同正在形成中的神经球共培养,检测异种细胞是否能与神经球形成杂合细胞球.结果 神经球在形成过程中,能与异种细胞形成杂合细胞球,杂合细胞不改变原神经球细胞的特性,且杂合细胞球的形成能促进杂合细胞的增殖. 结论 神经球能与异种细胞形成杂合细胞球,并能为细胞生长分裂提供特殊的微环境,这为神经球微环境的研究提供实验依据.