神经系统特异表达基因调控机理的研究进展

神经系统特异性基因正确的时空表达受细胞内外信号的调控,信号传导途径最终的靶位点是能结合特异转录因子的DNA序列.目前发现的决定神经系统基因特异性表达的顺式作用元件既有增强子,也有沉默子.它们可以特异性地增强基因在神经系统的表达,或特异性抑制基因在非神经系统的表达. 顺式元件要发挥这些作用,依赖于与其结合的反式因子,而这些反式因子又能与其他蛋白质或DNA序列发生互动, 通过协调作用,共同决定基因的时空表达顺序.     

真核基因表达的调节控制研究

真核基因表达的调控机制研究,主要集中在顺式作用元件和反式作用因子,以及它们相互作用规律上。RNA聚合酶Ⅱ转录的基因上游有两类调控元件,一类在转录起始位点的近端,大约100bp以内,有TATA,CCAAT,GGGCGG等序列,另一类在转录起始位点的远端,几百bp以外,有哺乳动物细胞的增强子和酵母细胞的上游激活序列等。与这些元件相结合的蛋白质因子已发现很多种,其中有些已被分离纯化。它们的分子内存在不同的功能区。真核基因的表达,涉及蛋白质与蛋白质,蛋白质与DNA相互作用等很多复杂反应。     

转录因子的巯基亚硝基化修饰及其生理学意义

巯基亚硝基化(S-nitrosylation)修饰是一种一氧化氮(nitric oxide, NO)介导的氧化还原依赖的、可逆性蛋白质翻译后修饰。生理条件下,S-nitrosylation通过调控蛋白质的稳定性、蛋白质活性、亚细胞定位及蛋白质-蛋白质相互作用,在维持细胞稳态中发挥重要作用。而在多种病理条件下,蛋白质S-nitrosylation及其产物表现出异常的升高或降低。转录因子又称反式作用因子,通过识别并结合调控元件而影响基因转录。本文简要综述转录因子的S-nitrosylation修饰的研究进展及其生理学意义。     

蛋白质磷酸化与基因转录的调节

蛋白质磷酸化与基因转录的调节敖世洲（中国科学院上海生物化学研究所,２０００３１）基因的转录受顺式作用元件和反式作用因子的控制,涉及很多蛋白质与ＤＮＡ,蛋白质与蛋白质之间的复杂反应,在这些反应中,蛋白质的磷酸化与去磷酸化起着重要的调节作用。在已详细研究的转录因子中,都存在磷酸化与非磷酸化的两种形式。磷酸化对转录因子的活性调节主要在三个水平上起作用：控制转录因子从细胞质到细胞核的运转,影响转录因子与特异DNA序列的结合, 调节蛋白质因子转录激活区与其他因子的作用。     

种子贮藏蛋白质表达调控及应用研究进展

种子在成熟过程中大量积累贮藏蛋白质,且不同植物种子中贮藏蛋白质的种类不同.为了解种子贮藏蛋白质的表达调控模式,对近年来表达调控机制的理论研究和在植物分类研究、分子育种及表达药用蛋白质方面的应用研究进行了综述.理论研究表明,种子贮藏蛋白质的特异性表达是受精确调控的,这些调控包括启动子中的顺式作用元件和反式作用因子.应用研究表明,通过对种子贮藏蛋白质表达的合理调控可提高作物的产量和营养价值,同时种子贮藏蛋白质具有稳定表达的特性,可用于研究植物分类、植物系统进化和表达药用蛋白质.     

染色质免疫沉淀技术在研究DNA与蛋白质相互作用中的应用

在后基因组时代,DNA-蛋白质的相互作用是研究基因表达调控的一个重要领域。与其他方法相比,染色质免疫沉淀技术（chromatin immunoprecipitation assay, ChIP）是一种在体内研究DNA-蛋白质相互作用的理想的方法。近年来这种方法与DNA芯片和分子克隆技术相结合,可用于高通量的筛选已知蛋白因子的未知DNA靶点和研究反式作用因子在整个基因组上的分布情况,这将有助于深入理解DNA-蛋白质相互作用的调控网络。总结了染色质免疫沉淀技术的方法,特别介绍了使用这些方法取得的最新进展。     

植物基因表达调控的机制：核因子作用

植物基因表达调控的机制：核因子作用邵宏波（四平师范学院生物工程研究所四平１３６０００）１引言真核生物的转录启始是由顺式作用的ＤＮＡ基序（ｅｔｓ－ａｃｔｉｎｇＤＮＡｍｏｔｉｆ）与反式作用的蛋白质因子（ｔｒａｎｓ－ａｃｔｉｎｚｎｒｏｔｅｉｎｆａｃｔｏｒ）...     

单股正链RNA病毒基因组3'非编码区的高级结构与功能研究进展

单股正链RNA病毒种类繁多,其宿主涉及人、动物、植物,对人畜健康和农业经济生产都有重大的影响.病毒基因组3'UTR内的序列形成茎环、假结、TLS等高级结构,既可以作为顺式元件,又可以结合蛋白质反式因子,对病毒的转录、复制、翻译都有调控作用.简要介绍了单股正链RNA病毒代表种属的3'UTR内高级结构与功能的研究方法、主要进展和存在的问题.     

一种特异识别SV40启动子的人工转录因子的构建

转录因子是真核表达调控中非常重要的一类反式作用因子,通常由DNA结合域与效应域两部分组成,而锌指结构是DNA结合域的常见组成单元。人工转录因子就是基于转录因子的这种结构特点,人为地选择针对特定序列的DNA结合域与具有特定作用的效应域组合而成。利用噬菌体展示技术,筛选到与SV40启动子上9bp序列特异结合的锌指结构,再连接KOX1的KRAB域构建了一种人工转录因子。转染实验表明它对SV40下游的报告基因的表达有很显著的抑制作用。     

真核生物mRNA非翻译区结构特征与mRNA翻译

真核生物中蛋白质合成通常在翻译水平受到调控,而mRNA非翻译区与mRNA翻译之间关系密切。真核生物mRNA非翻译区长度、mRNA二级结构、GC含量、顺式作用元件与反式作用因子、mRNA帽端结构和多聚腺苷酸尾等结构对翻译具有重要的调控作用。本文就真核生物mRNA非翻译区结构特征对其翻译的影响做一综述。     

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.