苏云金芽孢杆菌杀虫晶体蛋白毒性片段的结构域在毒杀昆虫中的作用

苏云金芽孢杆菌 (Bacillusthuringiensis)杀虫晶体蛋白的毒性片段包含三个不同的结构域。通过对毒性片段编码基因的定点诱变和体外重组 ,已经对结构域的功能有了较清晰的认识。一般认为结构域Ⅰ参与孔道的形成 ,结构域Ⅱ决定毒素与受体的特异性结合 ,结构域Ⅲ主要调节毒素的活性。本文根据国外研究 ,从毒素蛋白质结构的不同组织层次 ,阐述了这些区域的结构与其功能的关系。     

苏云金芽孢杆菌杀虫晶体蛋白毒性片段的结构域在毒杀昆虫中的作用

苏云金芽孢杆菌（Bacillus thuringiensis)杀虫晶体蛋白的毒性片段包含三个不同的结构域,通过对毒性片段编码基因的定点诱变和体外重组,已经对结构域的功能有了较清晰的认识,一般认为结构域Ⅰ参与孔道的形成,结构域Ⅱ决定毒素与受体的特异性结合,结构域Ⅲ主要调节毒素的活性。本文根据国外研究,从毒素蛋白质结构的不同组织层次,阐述了这些区域的结构与其功能的关系。     

苏云金芽孢杆菌杀虫晶体蛋白毒性片段的结构域在毒杀昆虫中的作用

苏云金芽孢杆菌（Bacillus thuringiensis)杀虫晶体蛋白的毒性片段包含三个不同的结构域。通过对毒性片段编码基因的定点诱变和体外重组,已经对结构域的功能有了较清晰的认识。一般认为结构域Ⅰ参与孔道的形成,结构域Ⅱ决定毒素与受体的特异性结合,结合域Ⅲ主要调节毒素的活性。本文根据国外研究,从毒素蛋白质结构的不同组织层次、阐述了这些区域的结构与其功能的关系。     

Cry毒素杀虫活性分子改造方法研究进展

苏云金芽胞杆菌(Bacillus thuringiensis,Bt)产生的Cry毒素为防治害虫提供了一种宝贵的资源。但昆虫中肠蛋白酶的活化作用在不同的昆虫中对Cry毒素的杀虫活性有限制性。分析了几种不同的策略来增加Cry毒素对靶标昆虫的毒性,包括结构域Ⅲ交换、结构域Ⅱ和结构域Ⅲ的突变以及其他突变。此外,还详细阐述了噬菌体展示技术进行毒素优化的方法,毒素优化能够增加Cry毒素对亲本Cry毒素敏感度较低的害虫的杀虫活性,以期为Cry毒素的分子改造和应用提供参考。     

炭疽致死因子的结构域及功能

致死因子(lethal factor, LF)是一种能水解丝裂原活化蛋白激酶(mitogen-activated protein kinase, MAPK)家族的金属蛋白酶,是炭疽毒素(toxin)的重要成分之一。炭疽LF由四个结构域组成:结构域Ⅰ主要负责与保护性抗原(protective antigen, PA)结合;结构域Ⅱ是主要功能区域;结构域Ⅲ具有高度可变性且能与底物特异性结合;结构域Ⅳ含有锌离子结合序列,发挥蛋白质的毒性作用。现就炭疽LF各个结构域的结构和功能,以及部分结构域中残基突变后对该蛋白质毒力的影响作一概述。     

c-Fos不同结构域的真核表达及功能鉴定

目的：克隆c-Fos蛋白不同结构域基因片段,构建其含FLAG标签的真核表达载体,并鉴定其功能。方法：用PCR方法扩增获得c-Fos不同结构域片段基因,定向克隆至本实验室保存的FLAG-peDNA3．0载体中,瞬时转染293T细胞进行表达,并以本实验室保存的HA-e-Jun与FLAG-c-Fos不同结构域片段免疫共沉淀鉴定其相互作用区域,以佐证所构建的c-Fos结构域克隆的正确性。结果：测序结果表明c-Fos不同结构域序列正确,Western印迹显示可以在真核细胞中获得表达,并且免疫共沉淀结果显示c-Jun可以与c-Fos的bZIP区域特异性结合。结论：构建并表达了c-F0s不同结构域片段,为进一步研究与c-Fos相互作用的蛋白及其区域定位奠定了基础。     

针对炭疽保护性抗原不同结构域的中和性单克隆抗体的筛选和鉴定

炭疽保护性抗原（PA）是炭疽毒素的重要组分,同时也是现有炭疽疫苗的主要有效成分,在炭疽杆菌的致病与免疫中发挥关键作用。以重组PA为免疫原,采用B淋巴细胞杂交瘤技术,结合炭疽毒素敏感细胞的毒性中和试验,大量筛选抗PA单克隆抗体,获得了9株炭疽毒素中和性单抗。进一步分析表明这些单抗以IgG1亚类为主,分别识别PA 3个结构域的4个不同中和表位区。针对结构域2的4株单抗识别同一表位区,其中3株单抗的中和活性强于抗PA多抗;针对结构域4的4株单抗识别两个不同表位区;另有1株单抗识别位于结构域3的表位。实验结果提示PA具有多个中和表位,分别位于其不同结构域,其中结构域2、4包含主要中和表位。实验中获得的针对不同表位的中和性单抗为深入研究PA的免疫保护机理提供了工具,也为研制针对炭疽毒素的被动免疫制剂和治疗药物打下基础。     

苏云金芽胞杆菌杀虫晶体蛋白的结构与功能研究进展

苏云金芽胞杆菌（Bacillus thuringiensis）杀虫晶体蛋白的毒性肽由三个典型的结构域组成.结构域Ⅰ位于肽链的N端,为一组由6～7个两亲的α螺旋围绕着一个疏水的α螺旋形成的α螺旋束,参与了细胞膜的穿孔;结构域Ⅱ位于肽链的中间,为三组以“希腊钥匙”（Greek key）拓扑结构连接在一起的反平行的β折叠片层,其顶端的突环参与了毒素与受体蛋白的结合;位于C端的结构域Ⅲ是由两组反平行的β折叠片层组成的夹心结构,以β果酱卷(jelly roll)拓扑结构排列,可能能够防止蛋白酶对毒素分子的过度降解.     

炭疽毒素保护性抗原的不同结构域对其表达可溶性的影响

目的：对炭疽毒素保护性抗原（PA）的不同结构域进行了缺失突变，以期找到免疫原性降低而功能变化不大的PA蛋白突变体。方法：在对PA结构域的缺失突变体进行表达时，意外发现不同的突变体表达效果之间存在很大差异，遂用DNAStar软件对PA的4个结构域和突变体进行分析。结果：PA蛋白结构域2的表面特性与其他结构域存在很大差异。结论：推断这种表面特性影响了PA突变体的可溶性特征。     

非核糖体肽合成酶缩合结构域基因片段克隆

从大连渤海海域筛选出1株放线菌L1,结合形态观察、生理生化实验和16S rDNA分子鉴定,确定L1属于链霉菌属球孢链霉菌(Streptomyces globisporus)。根据GenBank发布的非核糖体肽合成酶(NRPS)序列设计引物,从放线菌L1的基因组DNA中扩增获得NRPS基因片段。测序结果及比对分析表明该片段属于NRPS缩合结构域部分序列。三维建模显示其结构呈V型,包含缩合结构域核心序列,与数据库已知结构相一致,可以推断该克隆片段为NRPS缩合结构域基因片段,为后续深入研究缩合结构域特异性与相关NRPS功能提供基础。     

Photoregulation of seed germination of wild-type and of an aurea-mutant of tomato

Seed germination of an aurea mutant of tomato ( Lycopersicon esculentum Mill.) is promoted by continuous irradiation with red, far-red or long-wavelength far-red (758 nm) light as well as by cyclic irradiations (5 min red or 5 min far-red/25 min darkness). Far-red light applied immediately after each red does not change the germination behaviour. Seed germination of the isogenic wild-type, cv. UC-105, is promoted by continuous and cyclic red light while it is inhibited by continuous and cyclic far-red light and by continious 758 nm irradiation. Far-red irradiation reverses almost completely the promoting effect of red light. The promoting effect (in the aurea mutant) and the inhibitory effect (in the wild-type) of continuous far-red light do not show photon fluence rate dependency above 20 nmol m⁻² s⁻¹. It is concluded that phytochrome controls tomato seed germination throgh low energy responses in both the wild type and the au mutant. The promoting effect of continuous and cyclic far-red light in the au mutant can be attributed to a greater sensitivity to P_fr.     

六种藓类植物茎的比较解剖学研究

通过对6种藓类植物,即褶叶青藓(Brachythecium salebrosum(Web.et Mohr.)B.S.G.)、湿地匐灯藓(Plagiomnium acutum(Lindb.)Kop.)、侧枝匐灯藓(Plagiomnium maximoviczii(Lindb.)Kop.)、大凤尾藓(Fissidensnobilis Griff.)、大羽藓(Thuidium cymbifolium(Doz.et Molk.)B.S.G.)和大灰藓(Hypnum plumaeforme Wils.)嫩茎和老茎的石蜡切片和显微观察发现,同一藓类植株的嫩茎和老茎,茎结构稳定,不同种藓类植物茎横切面具有不同特征.植物体茎横切面形状、表层细胞的层数、细胞大小和细胞壁厚薄、皮层细胞大小和形状、中轴的有无以及比例等特征可以作为藓类植物的分科分类依据之一.     

真菌类遗传学分析的知识结构教学

本文以认知结构理论为指导,讨论了真菌类遗传分析与高等动植物遗传分析的内在联系,认为利用这种内在联系进行教学可收到好的效果并说明了作者的具体教学过程。 Abstract:In the paper, the relationship between genetic analysis of Fungi and genetic analysis of high animal and plant was discussed.A good results were obtained when we adopted this method in the teaching.     

Interconnection of parameters of regulation system of lipid peroxidation and of morphophysiological parameters of mouse liver

A complex analysis of seasonal fluctuations of the mean group parameters of the system of regulation of lipid peroxidation has been performed in liver of Balb/c mice. Association of lipid characteristics and morphophysiological parameters is studied in the Balb/c mouse liver. An inter-connection is revealed between the liver index and the amount of lysoforms of phospholipids, the scale and character of the interconnection differing essentially depending on proportion of phos-phatidylcholine in mouse liver phospholipids.     

History of the discovery of the mode of transmission of yellow fever virus

This essay documents and examines the historical circumstances and events surrounding the discovery of the mode of transmission of yellow fever virus in Cuba. Close scrutiny of the articles published by Walter Reed and his colleagues in 1900, 1901 and 1902 reveals their limitations as historic documents. Fortunately, other sources of information from that period survive in letters and documents written by individuals involved in the quest for the mode of transmission. Examination and comparison of those sources of information unveiled a fascinating story which reveals that misunderstandings engendered by published articles accorded merit where it was not fully due.     

Physiological characteristics of various species of strains of carboxydobacteria

Seven strains of aerobic carbon monoxide-oxidizing bacteria (carboxydebacteria) when growing on CO as sole source of carbon and energy had doubling times which ranged from 12–42 h. The activity profiles obtained after discontinuous sucrose density gradient centrifugation indicated that the CO-oxidizing enzymes are soluble and the hydrogenases are membrane-bound in all strains examined. The CO-oxidizing enzymes of Pseudomonas carboxydohydrogena, Pseudomonas carboxydoflava, Comamonas compransoris, and the so far unidentified strains OM2, OM3, and OM4 had a molecular weight of 230,000; that of Achromobacter carboxydus amounted to 170,000. The molecular weights of the CO-oxidizing and H₂-oxidizing enzymes turned out to be identical. The cell sonicates were shown to catalyze the oxidation of both CO and H₂ with methylene blue, thionine, phenazine methosulfate, toluylene blue, dichlorophenolindophenol, cytochrome c or ferricyanide as electron acceptors. Methyl viologen, benzyl viologen, FAD⁺, FMN⁺, and NAD(P)⁺ were not reduced. The spectrum of electron acceptors was identical for all strains tested. Neither free formate, hydrogen nor oxygen gas were involved in the CO-oxidation reaction. Methylene blue was reduced by CO at a 1:1 molar ratio. The results indicate that CO-oxidation by carboxydobacteria is catalyzed by identical or similar enzymes and that the reaction obeys the equation CO+H₂OCO₂+2H⁺+2e^- as previously shown for Pseudomonas carboxydovorans.Dedicated to Otto Kandler remembering almost three decades of enjoyable cooperation     

Modulation of allostery of pyruvate kinase by shifting of an ensemble of microstates

Since the introduction of the concepts of allostery about four decades ago, much advancement has been made in elucidating the structure-function correlation in allostery. However, there are still a number of issues that remain unresolved. In this review we used mammalian pyruvate kinase (PK) as a model system to understand the role of protein dynamics in modulating cooperativity. PK has a triosephosphate isomerase (TIM)(α/β)₈ barrel structural motif. PK is an ideal system to address basic questions regarding regulatory mechanisms about this common (α/β)₈ structural motif. The simplest model accounting for all of the solution thermodynamic and kinetic data on ligand-enzyme interactions involves two conformational states, inactive E^T and active E^R. These conformational states are represented by domain movements. Further studies provide the first evidence for a differential effect of ligand binding on the dynamics of the structural elements, not major secondary structural changes. These data are consistent with our model that allosteric regulation of PK is the consequence of perturbation of the distribution of an ensemble of states in which the inactive E^T and active E^R represent the two extreme end states. Sequence differences and ligands can modulate the distribution of states leading to alterations of functions. The future work includes: defining the network of functionally connected residues; elucidating the chemical principles governing the sequence differences which affect functions; and probing the nature of mutations on the stability of the secondary structural elements, which in turn modulate allostery.     

（鱼句）亚科花（鱼骨）型鱼类骨骼系统的比较

对我国花型Hemibarbuspattern鱼类作了骨骼系统比较,结果表明,此类型鱼类脑颅较长,副蝶骨平直或稍弯曲,眶蝶骨腹纵嵴发达(铜鱼Coreius septentrionalis例外),下颞窝和咽突中等大,基枕骨后突发达;脑颅中的上筛骨的后突、侧筛骨的外筛突,蝶耳骨的外突、上耳骨的后突、围眶骨和后颞窝等均有明显的差异;咽颅中的舌颌骨、尾舌骨、鳃盖骨和下咽齿的列数等又有显著的区别;附肢骨骼中的腰带骨、脊椎骨中的复合神经骨和第4椎骨腹侧的悬器等也有不同之处。据此,这些差异和区别可作为属间或种间的分类依据。