小麦硫代硫酸硫转移酶类似基因的克隆与定位

小麦-簇毛麦6VS/6AL易位系92R137含有抗白粉病基因Pm21。为了研究该易位系的抗病机理,应用mRNA差异显示和快速扩增cDNA未端（Rapid Amplification of cDNAEnd,RACE)技术对在白粉菌诱导后表达增强的基因进行了克隆,分离到1个命名为TaTST的全长cDNA序列。Northern杂交分析表明,TaTST基因在白粉菌诱导后表达明显增强,24h达到峰值,氨基酸序列同源性分析表明,TaTST与Datisca glomerata的硫代硫酸硫转移酶基因（rho-danese,EC,2.8.1.1)序列有64%相同,80%相似,用中国春缺体/四体系和端体系Southern杂交和基因特异性引物扩增（gene specific primer-PCR)将TaTST基因定位在小麦6B染色体短臂上,Southern杂交表明,该基因为单拷贝基因,由于在杨麦5号和6VS/6AL易位系间存在明显多态,可以推测在6VS上有TaTST的同源基因,TaTST是从小麦中分离的新基因。白粉菌诱导后的表达变化提示;TaTST与小麦抗白粉病反应有关。     

小麦3个被白粉菌诱导基因表达的分析

含有抗白粉病基因Pm2 1的小麦 簇毛麦 6VS/6AL易位系在接种白粉菌后 ,叶片无任何病症。应用mRNA差异显示技术从小麦 簇毛麦 6VS/ 6AL易位系分离到 3个叶绿体蛋白基因片段 ,它们是TaD5、TaD2 3和TaD33,3个基因片段分别与小麦叶绿体基因rbcL ,拟斯卑尔脱山羊草叶绿体RNA聚合酶α亚基基因rpoA和大麦 1,5 二磷酸核酮糖羧化酶活化酶基因(Rubiscoactivase ,RcaA2 )同源性达 97%、98%和 88%。据此推测TaD5、TaD2 3和TaD33分别是 6VS/ 6AL易位系中的rbcL、rpoA和 1,5 二磷酸核酮糖羧化酶活化酶基因的片断。Northern分析表明这 3个叶绿体基因的表达在白粉菌诱导下得到增强。叶绿体基因组含有胸腺嘧啶重复区是在mRNA差异显示中克隆到叶绿体基因组基因的原因     

用克隆池PCR法筛选小麦-簇毛麦易位系6VS/6AL基因组TAC文库获得抗病基因候选克隆

用根据抗病基因保守区设计的一对简并性引物,从小麦－簇毛麦易位系6VS／6AL cDNA中PCR扩增获得一个具有抗病基因核苷酸结合位点（Nucleotide binding site,NBS）结构特点的DNA片段克隆N7。从小麦－簇毛麦易位系6VS／6AL基因组TAC（Transformation-competent artificial chromosome,TAC）文库的22块96孔板提取所有2112个克隆池（每个池含约1000个克隆）的质粒,再根据N7的核苷酸序列设计一对特异引物,用克隆池PCR（pooled PCR)法经分级筛选从文库中获得一个阳性克隆。以N7为探针,通过Southern杂交证实了该TAC克隆为真正含有抗病候选基因的克隆。研究结果表明克隆池PCR法对克隆数目巨大的基因组文库的筛选很有效。     

牦牛α-乳清蛋白基因的克隆与序列分析

根据奶牛α－乳清蛋白基因序列设计引物,用PCR方法扩增并克隆了牦牛（Poephagens grunnieus）α－乳清蛋白基因的全序列。结果表明,在671－2689bp之间,共有4个外显子和3个内含子,牦牛α－乳清蛋白基因共编码142个氨基酸,其中第1－19氨基酸之间的短肽为信号肽序列。牦牛的α－乳清蛋白基因有较高水平的表达可能与基因内非编码序列碱基突变引起的回文结构消失有关。该基因5′侧翼序列在结构上牦牛和牛基本相同,只有MGF因子识别位点稍有差别。且牦牛的该序列更符合Groenen等1994年总结的该因子识别位点的模式序列,因此牦牛的该基因5′调控区可能更适于进行组织特异性表达的转基因动物的制作研究。     

小鼠PC-1基因在大肠杆菌中的表达和纯化

利用PCR和基因重组技术构建了小嫌PC－1基因全长cDNA及其N端45个氨基酸残基的表达质粒pGEX-4T-1-mPC-1和pGEX-4T-1-mPC-1-45。经IPTG诱导后,在大肠杆菌DH5α中,GST－mPC-1和GST－mPC-1-45两个融合蛋白都获得了可溶性高表达。经谷胱甘肽Sepharose-4B亲和柱层析纯化后,获得了纯的GST－mPC-1和GST－mPC-1-45蛋白。     

小麦Beclin1类似基因的分子克隆与鉴定

以小麦 簇毛麦 (Triticumaestivum Haynal diavillosa) 6VS/6AL易位系 92R1 3 7为材料 ,应用mRNA差异显示和快速扩增cDNA末端 (rapidam plificationofcDNAends,RACE)技术对在白粉菌(Blumeriagraminis)诱导后表达增强的基因进行了克隆。分离到一个与拟南芥Beclin1类似基因同源的全长cDNA克隆 ,暂定名为小麦Beclin1类似基因。它编码 441个氨基酸组成的多肽。二级结构推导显示与人类Beclin相似 ,具有螺旋结构。Northern杂交分析表明 ,小麦Beclin1类似基因在白粉菌诱导后表达增强。Southern分析证明 ,小麦Beclin1类似基因为单拷贝基因     

氮磷饥饿诱导的水稻糖转运体基因的cDNA克隆和鉴定

运用快速扣除杂交 (RaSH)方法构建了水稻氮饥饿诱导的cDNA文库。从该文库获得了一个cDNA克隆OsNSI1 (Oryzasativanitrogenstarva tion inducible 1 )。该全长cDNA编码 5 77个氨基酸 ,蛋白分子量为 6 1 .2kD。推测得出的氨基酸序列与其他物种的糖转运体有很高的同源性。水合性分析表明OsNSI1包含有 1 2个跨膜区域和一个中心亲水环。这些数据提示OsNSI1是一个糖转运体蛋白。Southern印迹分析表明OsNSI1是一个单拷贝基因。Northern印迹分析表明OsNSI1主要在叶及根中表达 ,氮、磷饥饿能强烈诱导其表达增强     

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.