用微生态的观点看中药有效成分在肠道的生物转化

微生态学与中医学的观点是极为相似的,中药有效成分口服后,被肠道微生物进行生物转化,药效会得到减弱或者增强。对肠道微生物转化中药有效成分与肠道微生态平衡关系的研究,将是解释中药作用机制不可忽略的一条途径。     

Evaluation of oxygen adaptation and identification of functional bacteria composition for anammox consortium in non-woven biological rotating contactor

In this study, the anammox consortium was found to adapt to the wastewater containing dissolved oxygen (DO), as the DO was gradually increased. Batch tests indicated the maximum aerobic ammonium oxidizing activity of the consortium was 1.38mmolNH(4)(+)-N(gVSS)(-1)day(-1), which played key roles in the oxygen consumption process; the maximum anaerobic ammonium oxidizing activity was slightly decreased after long-term oxygen exposure, but only from 21.23mmolNH(4)(+)-N(gVSS)(-1)day(-1) to 20.23mmolNH(4)(+)-N(gVSS)(-1)day(-1). Microbiological community analysis identified two strains similar to Nitrosomonas eutropha were responsible for oxygen consumption, which were able to exist in the autotrophic anaerobic condition for long periods and protect anammox bacteria Planctomycetales from the influence of oxygen. Microbiological composition analysis showed Nitrosomonas and Planctomycetales approximately accounted for 10% and 70% of the bacteria, respectively. The possibility of cultivation anammox consortium in presence of DO will lead to substantial savings of energy and resource in the industrial application.     

Quorum Sensing System Used as a Tool in Metabolic Engineering

Quorum sensing (QS) is a ubiquitous cell–cell communication mechanism in microbes that coordinates population‐level cell behaviors, such as biofilm production, virulence, swarming motility, and bacterial persistence. Efforts to engineer QS systems to take part in metabolic network regulation represent a promising strategy for synthetic biology and pathway engineering. Recently, design, construction, and implementation of QS circuits for programmed control of bacterial phenotypes and metabolic pathways have gained much attention, but have not been reviewed recently. In this article, the architectural organizations and genetic contributions of the naturally occurring QS components to understand the mechanisms are summarized. Then, the most recent progress in application of QS toolkits to develop synthetic networks for novel cell behaviors creation and metabolic pathway engineering is highlighted. The current challenges in large‐scale application of these QS circuits in synthetic biology and metabolic engineering fields are discussed and future perspectives for further engineering efforts are provided.     

Cys146-Cys146分子间二硫键在人瘦素二聚化过程中起主导作用

在前期研究中,已发现人瘦素（leptin）在体外再折叠过程中会形成稳定的二聚体,但其二聚化机制尚不清楚. 本研究旨在分析瘦素二聚体的结构特性,并重点研究体外再折叠过程中瘦素二聚化的机制. 相较与瘦素单体,瘦素二聚体保留了约75％免疫活性及15％受体结合活性,同时显示出明显慢的天然电泳迁移率. 圆二色性分析显示,二聚体基本保留了单体α螺旋索结构特征. 还原性及非还原性凝胶电泳分析和自由巯基测定结果表明,瘦素二聚体是由一对分子间二硫键连接2个单体而成的.为了确定瘦素二聚化过程中起主导作用的分子间二硫键,利用PCR定点突变技术构建了C96S和C146S两个突变体瘦素. 通过分析C96S及C146S突变体瘦素的体外再折叠特性及过程,并与野生型瘦素相比较,揭示C96S瘦素的二聚体显示出与野生型瘦素二聚体相似的特性,而C146S瘦素不能形成结构稳定的二聚体. 以上研究结果表明,Cys146-Cys146分子间二硫键在人瘦素二聚化过程中起主导作用.     

不同批号蕲蛇酶在家兔血液凝固系统上的生物活性检测

目的：研究不同批号蕲蛇酶静脉给予家兔后,对血液凝固系统各项指标的影响,以判定其药效的稳定性。方法：取家兔,纯白色,体重1．5－2．5kg,雌雄兼用,每日静脉注入蕲蛇酶1．0u/kg.d^-1,连用3－5天,药前、药后从心脏取血6ml,取全血1ml作血栓形成;余血以3．0％枸橼酸钠按1：9抗凝,分离富血小板血浆（PRP）,测定其血小板数目和血小板聚集率,以贫血小板血浆（PPP）测定凝血酶时间（TT）,凝血酶原时间（PT）,部分凝血活酶时间（KPTT）以及纤维蛋白原（Fg)含量。结果：5个批号的蕲蛇酶药后3天或5天均可明显使血栓形成的重量减轻,长度缩短,Fg含量减少（P＜0．01）,TT,PT,KPTT均延长（P＜0．05－0．01）,血小板数轻度减少,聚集率抑制达20％－50％,结论：不同批号的蕲蛇酶静脉给予家兔,具有显著的作用于血液凝固系统,导致血栓形成减少,表明对心脑血管内血栓形成药学相同,说明用家 兔作为鉴定药品质量是可行而必须。     

小麦族几种近缘植物细胞在长期离体培养中的染色体变异

对小麦及其4种近缘属间禾草进行了长时间 (0.5～5.7年, 个别8.6年) 的愈伤组织培养,在继代过程中染色体数目的变异在染色体倍性低的簇毛麦(Haynaldia villosa, 2n=2x=14)及新麦草(Psathyrostachys juncea, 2n=2x=14) 倾向于数目的增大;染色体倍性高的小麦 (Triticum aestivum, 2n=6x=42) 趋向于数目的减少;而倍性居中的羊草 (Leymus chinensis, 2n=4x=28) 既有增大也有减小;染色体倍性最高的高冰草 (Agropyron elongatum, 2n=6x=70) 最为稳定,但也有减少的趋向。愈伤组织的胚性主要与二倍体及亚二倍体的总水平相关。     

表观遗传学与人类表观基因组计划

表观遗传学已被用来描述许多生物学过程,成为生物学与医学领域中热点的学科之一.本文简要介绍表观遗传学与表观遗传基因组学的概念、人类表观基因组计划研究的目标与意义,并阐述DNA甲基化、组蛋白修饰、染色质重塑和非编码微小RNA等表观遗传学调控基因表达的机制.我们已经认识到人类疾病基因缺损可能部分或完全与表观遗传有关.所以,研究疾病状态下非突变的、可逆的表观遗传调节,以及治疗的可能性具有重要实际意义.     

大肠杆菌中表达关键基因产异丁醇的研究

目的:改造大肠杆菌的代谢途径,使非生产菌株大肠杆菌具备产异丁醇的能力.方法:将乳脂乳球菌NIZO B1157的2-酮酸脱羧酶基因kdcA克隆到大肠杆菌中,使大肠杆菌产异丁醇;另外,采取两种方法过量表达alsS、ilvC、ilvD基因,增加前体物质酮酸的供应,以提高异丁醇的产量:一是与kdcA串联表达;二是在另一个相容质粒中表达.结果:大肠杆菌工程菌具备产异丁醇的能力,其中相关基因在一个质粒中串联表达的产量比其在两个相容质粒中共表达的产量高30倍,达到3g/L.结论:导入的酮酸合成途径与醇类生产途径结合,能使非生产菌株大肠杆菌生产异丁醇,并且单质粒表达代谢途径相关基因的效果优于双质粒表达.