TBP与TBP相关因子

真核细胞中,一定数量和种类的TBP相关因子与TBP结合成多蛋白复合物--基本起始因子SL1、TFⅡD、TFⅢB,分别指导三类基因的转录.因此,TBP是一种通用转录因子,而TAFs则具有聚合酶和启动子特异性,起辅助转录激活因子的作用.在转录起始过程中,前者在种属间高度保守的C端独特结构可直接识别TATA元件,或通过TAFs与DNA结合;而后者有的作为TBP结合DNA的媒介,有的作为转录起始复合物组装时其他TAFs与TBP相互作用的桥梁,有的则作为转录激活蛋白与TBP联系的纽带,介导转录激活蛋白对基因转录的激活作用.     

斑马鱼TATA结合蛋白的生物信息学分析

斑马鱼TATA结合蛋白(TBP)是转录过程中的重要起始因子。利用生物信息学方法对斑马鱼TBP的理化性质、物种间同源性、保守结构域、跨膜区、亲水性/疏水性、蛋白质二级结构、蛋白质三级结构、蛋白质相互作用进行预测分析。分析表明,斑马鱼TBP全长302个氨基酸,等电点9.8,属于TATA结合蛋白超家族,不含跨膜区,属于亲水蛋白;二级结构以无规则卷曲为主,含5个α螺旋区和8个β折叠区,三维建模空间结构可信度98.9%,进一步分析建模结果可靠;与斑马鱼TBP相互作用的蛋白质均为转录因子或TFⅡD复合物组分。分析结果对于深入研究斑马鱼TBP在基因转录中的作用具有一定的理论指导意义。     

真核生物的增强子

真核生物的转录调控与原核生物相似,在转录起始位点上游大约30bp处有一个TATA box,它是基本的启动子成份。除TATAbox外,在-70bp处还有一个CCAAT box或 GGGCGG motif,它对基因的有效转录也是重要的。进一步的研究表明,真核基因的转录效率不仅由近端的启动子决定而且受远端调控元件的控制。增强子(enhancer)就是一个重要的调控元件。     

人端粒酶催化亚基hTERT基因启动子的克隆

为了确定人端粒酶催化亚基 h TERT基因的启动子结构特征 ,采用 Panhandle PCR技术 ,从正常人外周血单核细胞基因组 DNA中扩增 h TERT基因 5′端上游旁侧序列 ,结果获得了 h TERT基因翻译起始位点上游 2 0 90 bp的基因组 DNA序列。序列分析表明 h TERT基因的启动子区域缺少典型真核启动子的核心元件 ( TATA box和 CAAT box) ,但含有多个已知转录因子蛋白结合的核心序列 ,如 E box及 Sp1核心序列。提示 h TERT基因的表达可能受特殊的转录因子调控 ,这些转录因子的激活可能与癌变细胞中 h TERT重新组成型表达有关     

草原红牛IGF—I基因5’调控区序列的生物信息学分析

胰岛素样生长因子-I（IGF—I）基因为多启动子基因,也是影响动物生长发育和肉用性状的重要候选基因。在克隆草原红牛IGF-I基因5’调控区1954bP的基因组序列基础上,利用生物信息学软件,分析了IGF—I5’调控区的启动子结构;预测出评分在95分以上的转录因子结合位点有71个;分析结果没有发现CpG岛和TATA—box。研究结果为进一步研究IGF-I转录效率以及对草原红牛生长和肉用性状的影响奠定基础。     

基于序列和结构特征分析植物TATA和TATA-less启动子

分析启动子区域内调控元件是阐明基因转录起始机制的重要前提．利用从PlanPromDB数据库下载的植物Pol-ⅡTATA和TATA-less启动子数据,深入分析了两类启动子GC偏好、位点结构保守性、序列碱基组分、保守模体分布、TATA box位点分布及关联位点保守性等特点,统计出两类植物启动子许多特有的序列组分和结构规律,这些规律对进一步揭示植物Pol-Ⅱ启动子的转录调控机制有一定的帮助．通过构建能够同时考虑位点保守性和关联性的位点关联性权重矩阵扫描模型(PCWM), 利用相应打分函数(Score)对两类启动子进行区分,得到了较好结果, 说明PCWM的预测性能要优于单碱基的位点权重矩阵(PWM)．     

真核转录因子TFⅡD研究进展

结合转录因子 TFⅡD 结构与功能,论述了 RNA 聚合酶Ⅱ是如何从一个特异基因的转录起始点起动转录的.转录因子 TFⅡD 是一种序列特异的 DNA 结合蛋白因子,它首先与含 TATA 的启动子形成前起始复合物,后者指导 RNA 聚合酶Ⅱ和其它基本转录因子最终组装成转录起始复合物.很多转录激活因子均通过与 TFⅡD 相互作用,控制转录起始复合物的组装或影响其稳定性,调节基因转录.因此,TFⅡD是一种极其重要的基本转录因子.     

空间飞行水稻pi-hit-1基因启动子功能分析

pi-hit-1基因是本实验室通过空间诱变找到的一个水稻新基因。为了对pi-hit-1基因启动子结构和功能进行研究,首先使用植物启动子分析数据库(PlantProm DB-TSSP,TFSEARCH,PLACE及PlantCARE)对该基因转录调控区序列进行预测分析,结果显示该基因上游调控区存在多个顺式元件,主要集中在翻译起始位点前300bp的区域,转录起始位点位于翻译起始位点前100bp,在转录起始位点前132bp存在TATA box元件。凝胶电泳迁移率实验(EMSA)发现翻译起始位点上游约300bp存在转录因子特异结合位点,为该基因的核心启动子,这与预测结果一致。采用系统生物学的方法研究水稻新基因pi-hit-1启动子结构,发现了该基因的核心启动子元件,为研究空间环境如何影响基因的转录调控提供了重要依据。     

粘虫核型多角体病毒凋亡抑制基因的定位、序列和启动子结构

以AcNPV凋亡抑制基因p35为探针,与LsNPV DNA的限制性片段和LsNPV DNA EcoRV片段杂交,发现EcoRV 5.5kb片段有强烈的杂交信号.将此片段亚克隆后,测定了1244bp序列,发现一个完整的ORF,推导的302个氨基酸与AcNPV p 35蛋白有70.4%的氨基酸同源性,证明所测ORF为LsNPV的p 35基因.结构分析发现其5′端有早期基因启动子元件GC、ACGT和TATA box.有22 bp的顺向重复序列,包括由两个重叠的TATA box和上下游两个ACGT motif组成的两套启动子元件,这些结构特征与AcNPV的凋亡抑制基因十分相似.     

鼻咽癌恶性转化基因Tx中3.0kb片段序列分析

从中国人鼻咽癌细胞株 CNE2中克隆分离出的恶性转化基因 Tx,其基因长度为 1 6kb.在对其中 2 .8kb片段测序的基础上 ,对其中 Xho /Eco R 长度约 3.0 kb的片段 ( Tx3.0 )进一步进行了测序 ,并利用生物信息学技术分析认为 ,Tx3.0与人类免疫球蛋白 kappa( Igκ)轻链基因高度同源 ,并直接映射于 J区 .Tx3.0中除有编码免疫球蛋白 kappa链的 J2、J3、J4及 J5基因片段外 ,在各个片段间不仅有 TATA box、CAAT box和 Poly A等经典的调控序列 ,还有 NF- IL6的反应元件、某些转录因子的识别序列、以及核基质结合序列等 .据此以及 2 .8kb序列的分析结果 ,对 Tx3.0下游 1 .0 kb片段序列进行了预测 .对 Tx3.0基因片段的研究为进一步研究 Tx基因在鼻咽癌发病中的作用 ,提供了重要信息 .     

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.