湖北海棠MhPR1a基因的克隆与表达特性分析

以水杨酸诱导的湖北海棠[ Malus hupehensis (Pamp.) Rehd.]全长cDNA文库和基因组DNA为模板,克隆其PR1a基因(MhPR1a)的全编码区序列,并对该序列进行生物信息学分析;在此基础上利用荧光定量RT-PCR技术对湖北海棠根、茎和叶中该基因的表达特性及经过10μmol·L-1ABA、4℃低温处理及苹果蚜虫(Aphis citricola van der Goot)侵染后叶中该基因的表达特性进行了测定.结果表明:克隆获得的MhPR1a基因全长518 bp,最大开放阅读框为492 bp,编码162个氨基酸残基;编码的蛋白质为酸性蛋白,其相对分子质量为16 960,等电点pI 5.46;其基因组DNA序列与cDNA序列完全一致,说明MhPR1a基因内部没有内含子.湖北海棠MhPR1a基因与苹果(M.domestic Borkh.)和沙梨[Pyrus pyrifolia( Burm.f.)Nakai] PR1基因的cDNA序列及其编码的氨基酸序列同源性均较高,其中cDNA序列的同源性均为97％,氨基酸序列的同源性分别为95％和97％;系统树也显示MhPR1a基因编码的氨基酸序列与苹果和沙梨的亲缘关系最近,聚为一类.MhPR1a基因编码的氨基酸序列具有SCP保守结构域,含有1个信号肽和6个保守的半胱氨酸残基.在湖北海棠的叶、茎和根中MhPR1a基因均能表达,在根中的表达量最高.10 μmol·L-1ABA和4℃低温处理48 h后均可诱导MhPR1a基因的表达,且相对表达量明显高于对照(处理0h);苹果蚜虫也可诱导MhPR1a基因的表达,说明MhPR1a基因在湖北海棠抵抗植食昆虫和低温胁迫的过程中可能发挥着重要作用.     

利用改进的cDNA RDA技术分离胡萝卜(Daucus carota L.)体细胞胚根发育相关的基因

根据链霉亲和素与生物素之间的结合作用及磁性吸附分离的原理,发展出改进的cDNA代表性差式分析(representational difference analysis,RDA)技术,并用来检测在调控和解调控培养12h的胡萝卜体细胞胚中特异表达的基因.结果显示,在解调控12h的胡萝卜体细胞胚中,存在4条特异表达的cDNA片段,命名为NR-1,NR-2,NR-3和NR-4.将这些片段分别克隆在pBS噬菌粒载体中.DNA序列同源性比较表明,片段NR-3和NR-4分别与植物的DnaJ和木质葡聚糖内转糖基化酶(xyloglucan endo-transglycosylase)的编码基因有很高的同源性,而片段NR-2中有一段序列与LEA蛋白(late embryogenesis abundant proteins)基因有一定的同源性.NR-1则可能来自新基因.用32P标记NR-1作探针,与cDNA片段群体进行杂交证实,从解调控12h的胡萝卜体细胞胚中克隆到一种与胚根发育相关的新基因序列.Southern杂交表明,此基因在胡萝卜基因组中可能以单拷贝或低拷贝的形式存在.     

黄瓜中CBF1基因的克隆及其表达分析

以黄瓜中RNA为模板,RT-PCR扩增出CBF1基因cDNA序列的部分片段。测序表明此基因与黄瓜CBF1基因的同源性达99．44％。RT-PCR方法检测结果显示,CBF1基因在低温和盐胁迫下的黄瓜中表达,而在干旱和ABA胁迫下则不表达。     

马铃薯POTHR-1 cDNA的克隆及晚疫病菌和其他非生物因子诱导表达分析

利用RACE和重叠延伸相结合的方法,从经晚疫病菌接种诱导的马铃薯水平抗性材料叶片中克隆了一个POTHR-I基因(potato Phytophthora infestans-induced hypersensitive response related protein gene)的全长cDNA。序列分析表明,该基因编码225个氨基酸,与烟草harpin诱导蛋白基因hinI有很高的同源性(编码区核苷酸和氨基酸序列分别为83％和81％)。Southern杂交结果显示在马铃薯基因组中有2、3个拷贝。对其诱导表达模式研究表明：晚疫病病原菌接种36h后,该基因表达迅速增加;机械伤害及茉莉酸(JA)处理能够诱导表达;渗透胁迫(NaCI浸泡)能够诱导其微弱表达;但水杨酸(SA)不能诱导表达。该基因可能和病原与寄主互作时寄主产生过敏反应及细胞生理性死亡有关。     

黄瓜扩张蛋白基因CsEXP10的克隆与表达

以cDNA-AFLP差示片段的序列（CO434610）为基础,通过RACE延伸和与EST序列拼接,得到长度为1191bp的、包含完整3’末端的CsEXP10基因cDNA序列。Southern杂交结果表明,该基因在黄瓜基因组中以单拷贝形式存在．RT-PCR检测发现,该基因不在根、茎和叶中表达,而在果实中表达．Northern杂交显示,该基因在授粉后迅速生长的幼果中丰量表达,而在幼小子房、开花当天的未授粉子房和生长停止的果实中不表达,由此推测CsEXP10基因与授粉后黄瓜果实膨大生长有密切关系。     

马铃薯POTHR-1 cDNA的克隆及晚疫病菌和其他非生物因子诱导表达分析

利RACE和重叠延伸相结合的方法,从经晚疫病菌接种诱导的马铃薯水平抗性材料叶片中克隆了一个POTHE 1基因(potato Phytophthora infestans induced hypersensitive response related protein gene)的全长cDNA.序列分析表明,该基因编码225个氨基酸,与烟草harpin诱导蛋白基因hinl有很高的同源性(编码区核苷酸和氨基酸序列分别为83%和81%).Southern杂交结果显示在马铃薯基因组中有2～3个拷贝.对其诱导表达模式研究表明:晚疫病病原菌接种36 h后,该基因表达迅速增加;机械伤害及茉莉酸(JA)处理能够诱导表达;渗透胁迫(NaCl浸泡)能够诱导其微弱表达;但水杨酸(SA)不能诱导表达.该基因可能和病原与寄主互作时寄主产生过敏反应及细胞生理性死亡有关.     

不结球白菜BcTuRsO基因的克隆及表达

从不结球白菜抗病品种短白梗中克隆到一个抗芜菁花叶病毒(TuMV)相关基因,命名为BcTuRsO(Gen-Bank登录号FJ600376).该基因核苷酸序列全长650 bp,编码194个氨基酸,与已克隆的抗病基因有不同程度的同源性.系统进化树分析表明,该基因在不同物种之间具有保守性.基因组DNA杂交表明,BcTuRsO基因可能以单拷贝形式存在,其表达是组成型的.实时定量PCR检测表明,芜菁花叶病毒能够诱导不结球白菜BcTuRsO基因的转录表达,其在不结球白菜叶片中的表达特征说明它可能参与寄主对病毒的抗性.     

盐地碱蓬GST基因的克隆、序列分析及其表达特征

从盐地碱蓬 (Suaedasalsa)幼苗的cDNA文库中克隆到一个 0 .9kb的全长cDNA ,同源性分析表明该全长cDNA与已报告的大豆 (Glycinemax)GST基因相应序列的同源性达 5 5 % ,可能编码由 2 35个氨基酸组成的谷胱甘肽转移酶 (glutathioneS transferase ,GST)。Southern杂交结果证明GST基因在碱蓬基因组中可能有至少两个以上的拷贝 ;Northern杂交结果表明 ,4 0 0mmol/L的NaCl处理 4 8h ,幼叶中GSTmRNA的表达量是对照的 2～ 3倍 ,说明碱蓬中GST基因受盐诱导     

银杏叶绿体petD基因的克隆与表达

根据黑松、云杉、菠菜与玉米叶绿体petD基因序列设计引物,以银杏叶绿体基因组DNA为模板,PCR扩增克隆了银杏叶绿体petD基因（GenBank登录号为DQ923066,命名为GbpetD）的序列。序列分析显示,GbpetD基因组DNA序列编码区长1243bp,含1个内含子和2个外显子,其外显子序列编码177个氨基酸。相似性比对显示,该基因编码区序列与云杉、台东苏铁、黑松、莴苣、木薯、北美落叶松的petD基因核苷酸同源性为84％-99％,氨基酸序列同源性为85％-93％。系统进化树分析结果表明GbpetD蛋白质与黑松、北美落叶松、云杉、苏铁等裸子植物的petD蛋白质聚类关系最近。半定量RT—PCR分析表明,GbpetD基因在银杏叶和茎中表达,在叶中表达量最大。     

小麦维生素E基因TaHGGT-7AL的克隆与表达分析

从小麦（Triticum aestivum L.）品种‘科农199’籽粒中克隆出维生素E基因TaHGGT-7AL及其另外两个拷贝,通过生物信息学分析,对其序列结构特征及蛋白序列的系统发育关系进行了初步研究。结果显示：TaHGGT-7AL基因编码区长1227 bp,共编码408个氨基酸;TaHGGT-7AL与另外两个拷贝的序列一致性为95.45%。TaHGGT-7AL蛋白序列具有9个α-螺旋,该序列与禾本科HGGT蛋白的同源性在58.7%~98.5%之间。3个TaHGGT基因分别位于小麦基因组的7AL、7BL和7DL染色体上,均具有与膜相关的UbiA异戊烯基转移酶家族的保守结构域和一个转运肽。系统进化分析结果表明,TaHGGT-7AL与禾本科植物的亲缘关系较近。qRT-PCR分析结果显示,TaHGGT-7AL只在小麦颖壳和籽粒中表达,且在花后13 d籽粒的表达量最高。在ABA、4℃低温、干旱及黑暗胁迫处理下,TaHGGT-7AL表达量上调;NaCl处理24 h后,该基因表达量升高,表明TaHGGT-7AL可以对非生物胁迫产生响应。     

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.