苏云金芽孢杆菌双组份信号转导系统的生物信息学分析

苏云金芽孢杆菌(Bacillus thuringiensis)能产生杀虫晶体蛋白等多种活性成分,是目前应用最广泛的微生物杀虫剂。本文采用生物信息学方法,系统分析了由本实验室完成全基因组测序的苏云金芽孢杆菌YBT-1520、CT-43和BMB171 3个菌株的双组分信号转导系统(Two-componentsignal transduction system,TCS)的分布、结构及功能,并初步构建了部分TCS的调控网络关系图。本研究旨在为深入研究苏云金芽孢杆菌的生长、代谢以及毒力因子的表达与调控,全面了解伴孢晶体的形成机制开辟新的研究方向。     

发酵动力学教学释疑解难尝试

在发酵动力学课程教学中,针对菌体生长速率与菌体比生长速率、菌体实际生长得率系数(Yx/s)与理论生长得率系数(Ygs)、产物实际得率系数(Yp/s)与理论得率系数(Yps)、补料分批发酵中比生长速率调控等常见知识难点进行了释疑解难尝试,收到了较好的课堂教学效果。     

苏云金芽孢杆菌毒蛋白发掘方法的研究进展

自上世纪初发现苏云金芽孢杆菌对昆虫有杀虫活性以来,如何发掘利用苏云金芽孢杆菌的杀虫晶体蛋白服务于农业生产和人类的卫生防控就成为一个重要课题。从早期的分离菌株使用菌体的复合物喷施到使用分子手段转化植物特定表达,人类在苏云金芽孢杆菌杀虫晶体蛋白的利用精准度上在不断提高,但随之而来就是抗性的产生。因此不断发掘可使用的新的苏云金芽孢杆菌杀虫晶体蛋白基因资源就是一个很重要的话题。本综述就苏云金芽孢杆菌杀虫晶体蛋白基因的发掘方法研究做一系统论述。     

生物防治

960285 设计高效抗鳞翅目和鞘翅目昆虫的重组苏云金芽孢杆菌菌株[俄]/Kuzina, L. V.…∥Biotekhnologiya.-1994,7.-15～19[译自DBA,1995,14(8),95-04683] 将苏云金芽孢杆菌subsp.Kurstaki HD1负责晶体蛋白CryIA(b)合成的44MDa质粒分别接合转入不合成晶体蛋白的苏云金芽孢杆菌subsp.thuringiensis98和苏云金芽孢杆菌subsp.tenebrionis1516变种中,构建了重组的苏云金芽孢杆菌     

利用PCR技术直接鉴定苏云金芽孢杆菌杀虫晶体蛋白基因型的快速方法

根据PCR程序中热变性温度可使菌体裂解,释放出DNA的原理,利用苏云金芽孢杆菌杀虫晶体蛋白不同基因型的特异混合引物,对苏云金芽孢杆菌营养体直接进行PCR分析。根据不同基因型的特异扩增产物片段的分子量大小便可直接确定该苏云金芽孢杆菌杀虫晶体蛋白的基因型。本文对本室筛选天然菌株和苏云金芽孢杆菌克隆菌株分别进行了cryl基因的PCR分析。表明,该法结果可靠快速易行,在方法学上,为苏云金芽孢杆菌菌株鉴定、新菌株的筛选和基因型分析提供了极大的方便。     

费氏中华根瘤菌M6-3合成多聚羟基丁酸的发酵动力学研究

采用分批和连续培养的方法对中华根瘤菌M6 - 3合成多聚羟基丁酸的发酵动力学进行了研究 ,实验结果表明 ,该菌合成多聚羟基丁酸的发酵类型属于部分生长关联型。其细胞生长速率与限制性基质葡萄糖之间的关系符合Monod方程式。其合成PHB的速率公式为 :dpdt=0 0 76 2x - 0 2 192 dxdt,细胞的生长耗糖得率系数 (yG)为 1 4 1(g干细胞 g葡萄糖 ) ,细胞的维持耗糖系数 (m)为 0 0 34 (g葡萄糖 h·g细胞 ) ,产物得率耗糖系数 (yp)为 0 133(gP(3HB) g葡萄糖 ) ;并且通过实验与回归数理分析建立了一系列发酵动力学模型。     

生物防治

961860 对夜蛾科害虫具高活性的苏云金芽孢杆菌杀虫晶体蛋白[英]/Lambert,B.…//Appl.Environ.Microbiol.-1996,62(1).-80～86[译自DBA,1996,15(4),96-02167] 从苏云金芽孢杆菌血清变种tolworthiBTS02618A中分离出一种新型晶体蛋白(CP)     

苏云金杆菌δ-内毒素、芽孢及苏云金素A对棉铃虫毒性及拒食性的比较

苏云金杆菌库斯塔克变种HD-1的晶体蛋白与芽孢、HD-1无晶体突变株(Cry-)的芽孢以及苏云金素A对棉铃虫Helicoverpa armigera毒性和拒食性的比较研究显示,HD-1晶体蛋白对棉铃虫的杀虫毒力高, 拒食作用强; HD-1芽孢对棉铃虫具有一定的杀虫活性和生长抑制作用, 并有很强的拒食作用; HD-1无晶体突变株(Cry-)芽孢对棉铃虫无毒也无拒食作用;苏云金素A对棉铃虫的生长发育有极显著的抑制作用, 但对棉铃虫无拒食作用,由此证明晶体蛋白是苏云金杆菌杀虫活性和拒食作用的主要来源。苏云金素A与苏云金杆菌芽孢晶体混合物一起使用, 可使棉铃虫的死亡率显著提高。     

抗虫性增强的重组Bt晶体蛋白

为了获得具有新特性的苏云金芽孢杆菌晶体蛋白(Cry)并鉴定其参与杀虫活性的区段,植物育种和繁殖研究DLO-中心的Dirk Bosch及其同事经体内重组制备了含cryIC和cryIE的杂合基因。苏云金芽孢杆菌中的一些蛋白在菌体内以晶体形式累积并对多种昆虫幼虫有毒性,研究人员把这一现象用于植物遗传工程,以期能够提高植物对害虫的抗性。     

苏云金芽孢杆菌Cry1Ac杀虫晶体蛋白及其分子设计

cry1Ac编码的杀虫晶体蛋白是苏云金芽孢杆菌(Bt)产生的多种杀虫晶体蛋白中对鳞翅目昆虫有很高毒性的蛋白.第一个Cry1Ac杀虫晶体蛋白最早在库斯塔克亚种HD73中以伴胞晶体形式分离获得,其编码区为3 534 bp,编码蛋白分子量为133 kD,含1 178个氨基酸,等电点为4.84.自此以来,Cry1Ac杀虫晶体蛋白结构、功能以及应用研究一直是Bt杀虫晶体蛋白研究的重要方向.本文介绍了苏云金芽孢杆菌中应用最广泛的Cry1Ac杀虫晶体蛋白家族的结构、功能及其基因分类,并进一步就基于苏云金芽孢杆菌Cry1Ac杀虫晶体蛋白的基因工程研究做了分析,提出了持续利用BtCry1Ac杀虫晶体蛋白的一些见解.     

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.