花粉介导法获得玉米转基因植物株

利用花粉作为外源基因的载体进行遗传转化在玉米（Zea mays L.）上获得了成功。以玉米自交系太9101、综31等为受体,以pGLⅡ-RC-1质粒为供体,在玉米开花期,用花偻与质粒DNA混合并附加超声波处理,然后辅以人工授粉的方法将个源基因导入到受体中。DNA斑点杂交和PCR扩增以及PCR－Southern blot杂交检测结果证明,几丁质酶基因确已导下玉米自交系中。所得结果表明：玉米花粉可以介导外源基因的转化。利用花粉作为载体介导外源基因转化,避免了传统的基因枪法和土壤杆菌法转化所要求的组织培养技术,转化方法简单,易操作,具有很强的实用性。     

利用微滴数字PCR方法快速分析转基因玉米中外源基因的拷贝数

以玉米自交系501幼胚为受体材料,首先将来自球形节杆菌的EPSPS基因(G23V)按玉米密码子偏爱性进行优化与人工合成,并且将其克隆到表达载体pBAC9200中;然后利用农杆菌介导法将质粒载体转入玉米自交系501的幼胚中。经过愈伤诱导、草甘膦抗性筛选和分化培养最终获得14株转化再生植株。经PCR、RT-PCR检测表明,其中5株目的基因G23V-EPSPS稳定整合且在转录水平获得表达。随后,利用微滴数字PCR技术对外源基因拷贝数进行了检测分析,分析结果表明在5株阳性转基因植株中,外源基因G23V-EPSPS拷贝数分别为0.12、1.0、0.9、1.89和0.66,介于0~2之间。成功建立了草甘膦抗性基因G23V-EPSPS在玉米中的遗传转化体系,为以新型高抗草甘膦G23V-EPSPS基因作为转基因玉米筛选标记基因奠定了基础;而且以微滴数字PCR技术代替传统的Southern Blot简便快速的完成外源基因拷贝数的分析,为微滴数字PCR技术在转基因外源基因拷贝数检测上的广泛应用做了初步的探索。     

小麦恢复可育基因非配子融合的转移

由于利用了根癌农杆菌作为载体的DNA 转移系统,高等植物中的双子叶植物基因转移 获得了成功。但根癌农杆菌的天然寄生范围仅 限于双子叶植物,因此,单子叶植物的转化尚待 探索其他途经。有人采用单细胞或原生质体摄 取外源DNA,再生成愈伤组织,进而培育成完 整植株‘”。有人为了避开从细胞培养成植株的 某些困难,设想采用配子作为接受外源DNA的 受体,在体外培养花粉,把精子作为显微注射 DNA的靶子,再由花粉管进人子房,通过受精 将外源遗传物质引人到合子,从而形成转化的 胚,再发育为转化的植株［[91。还有人设想,以雌 配子作为显微注射DNA的靶子,将外源DNA 直接注射入卵细胞,然后通过受精,使外源DNA 进人受精卵,发育为转化的胚及转化的植 株^[2,3,5,4,10]。此外,最近有人报道,已经重组了 Ti质粒,可在单子叶植物玉米中作为外源DNA 转移的载体L川。但在单子叶植物的禾本科农作 物中,如小麦、水稻、玉米等,至今仍缺少可行的 外源基因转移技术。     

农杆菌介导法向玉米萌发种子转化bar基因的研究

以玉米(Zea mays L.)自交系‘昌7-2'的种子作为受体,质粒pCAMBAR.CHI.11为供体,采用农杆菌介导植物萌发种子基因转化方法将bar基因导入受体材料.PCR和Southern blotting杂交分析结果证明转化成功,转化率在6%左右.转化材料以0.2%Basta溶液喷雾后可正常生长发育.结果证明,农杆菌介导植物萌发种子转化,是适于玉米基因遗传转化的有效方法.     

农杆菌介导法向玉米茎尖导入抗草甘膦EPSPS基因的研究

以玉米自交系郑58的茎尖为受体,通过农杆菌介导法将抗草甘膦EPSPS基因转入玉米中,研究以茎尖为受体的农杆菌转化体系的可行性。98株转化苗,经过300 ppm的除草剂(农达)筛选,共获得13株转基因植株,经PCR检测,其中7株表现阳性,转化率达7.14%。初步证明外源基因已经整合到玉米基因组中,以玉米茎尖作为受体的转化系统用于基因转化是可行、高效的。     

花粉介导法获得耐草甘膦玉米植株及其耐性研究

为获得耐草甘膦转基因玉米植株,进而研究其除草剂耐性及外源基因的遗传特性,以质粒p BI101-aroA-M12为外源基因供体,以玉米自交系昌‘7-2’为受体,采用花粉介导法将外源基因导入玉米自交系中。PCR扩增、Southern杂交分析的结果证明获得了54个转基因植株;对其后代株系的分子检测及田间生物学鉴定,结果证明目的基因可以稳定遗传给后代植株,且赋予和提高了转基因植株的除草剂耐性。目的基因在转化体中的遗传规律研究,结果显示导入的目的基因在F2受体植株中以3∶1的比例发生遗传分离,符合孟德尔单因子显性遗传分离规律。ELISA分析和蛋白质浓度测定的结果证实目的基因在转化植株中得到表达,表达量介于40.5-112.6 ng/g叶片鲜重之间,目的基因表达量与该植株的除草剂耐性性状间呈极显著相关,r=0.942 3(P0.01)。最终研究获得了4个高草甘膦耐性的转基因纯合株系。     

影响农杆菌介导玉米优良自交系遗传转化的因素

以我国玉米骨干自交系9046,齐319,414,Mo17的幼胚为材料,在已经建立的农杆菌介导的玉米幼胚转化体系的基础上,研究了影响农杆菌介导玉米优良自交系遗传转化的因素,建立了优化的玉米优良自交系的遗传转化体系。研究结果表明,1．0—2．0mm的玉米幼胚是最适宜的转化受体;在感染液和共培养基中都加入乙酰丁香酮(200μmol／L)和抗坏血酸(50mg／L),能显著提高农杆菌对玉米的侵染能力;而感染前将幼胚高渗透压预处理未能提高转化率;延迟筛选有利于提高抗性愈伤组织的存活率。应用优化后的转化体系,获得了这4个玉米优良自交系的转基因植株,PCR阳性植株率为1．71％-4．09％。转化植株叶片总DNA的PCR和Southern杂交分析表明,T-DNA上的外源基因已经整合进了玉米基因组,并且在大多数转基因植株(71．4％)中为单位点插入。这一体系的建立,为进一步将有用基因导入玉米优良自交系奠定了基础。     

农杆菌介导的玉米遗传转化研究进展

农杆菌介导的转基因法是目前玉米遗传转化的主流方法之一。目前,模式玉米种质幼胚的转化体系已程式化,且开发了新筛选基因和获得不含筛选基因转基因玉米的方法,但是大多数育种骨干自交系转化频率低和转化受体基本上是幼胚。从农杆菌、受体及培养条件多方面各种因素对问题进行分析,多数研究认为针对特定基因型和受体材料建立好的受体再生系统,结合高效率农杆菌转化体系,获得多目的基因聚合(无其它外源片段)的转基因玉米将是农杆菌介导玉米转化体系研究的最终目标。本文主要从农杆菌介导(转基因)法应用于玉米遗传转化的历史、现状、问题等方面进行综述,为同领域的研究者提供一定的参考。     

影响农杆菌介导玉米优良自交系遗传转化的因素

以我国玉米骨干自交系9046,齐319,414,Mo17的幼胚为材料,在已经建立的农杆菌介导的玉米幼胚转化体系的基础上,研究了影响农杆菌介导玉米优良自交系遗传转化的因素,建立了优化的玉米优良自交系的遗传转化体系.研究结果表明,1.0-2.0mm的玉米幼胚是最适宜的转化受体;在感染液和共培养基中都加入乙酰丁香酮(200μmol/L)和抗坏血酸(50mg/L),能显著提高农杆菌对玉米的侵染能力;而感染前将幼胚高渗透压预处理未能提高转化率;延迟筛选有利于提高抗性愈伤组织的存活率.应用优化后的转化体系,获得了这4个玉米优良自交系的转基因植株,PCR阳性植株率为1.71%-4.09%.转化植株叶片总DNA的PCR和Southern杂交分析表明,T-DNA上的外源基因已经整合进了玉米基因组,并且在大多数转基因植株(71.4%)中为单位点插入.这一体系的建立,为进一步将有用基因导入玉米优良自交系奠定了基础.     

花粉作为外源基因媒介的植物遗传转化

以花粉作为外源DNA的媒介,获得转基因植株是有潜力的遗传转化体系。它可避免离体培养过程中的遗传变异和转基因植株的嵌合现象。本文介绍以花粉为外源基因的载体,利用植物有性生殖过程和小孢子胚胎发生两条途径进行植物遗传转化的研究进展。     

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.