高等植物在发根农杆菌介导下的遗传转化

本文介绍了发根农杆菌的生物学特性、遗传转化的操作技术、RiT-DNA转化体的形态特征以及发根农杆菌转化的利用。与根癌农杆菌不同,农杆碱型发根农杆菌的RiT-DNA含有生长素合成基因、农杆碱、甘露碱合成基因,不含有细胞分裂素合成基因,它的转化体首先是转化根。发根农杆菌介导的植物遗传转化,在次生代谢产物生产,植物抗逆性育种以及细菌与植物进化关系的研究等方面具有广泛的应用前景。     

农杆菌介导的单子叶植物遗传转化研究进展

根癌农杆菌(Agrobacterium tumefaciens)Ti质粒转化系统的建立使植物遗传工程进入了一个飞速发展的时期。近年来,发根农杆菌(A.rhizogenes)Ri质粒毛根转化系统的研究十分迅速,展示了美好的前景,农杆菌介导的植物遗传转化已成为目前研究和应用最广泛的系统。但是,农杆菌的宿主范围一般仅限于双子叶植物和一些裸子植物,这就直接防碍着这种比较完善的基因转移技术在单子叶植物,尤其是禾谷类作物转化的应用。本文介绍了农杆菌介导的单子叶植物遗传转化的进展;对扩大农杆菌宿主范围、实现对单子叶植物转化的途径进行了探讨。 (一)农杆菌介导的单子叶植物转化的方法 目前建立的单子叶植物基因转移系统有:(1)农杆菌载体系统;(2)外源DNA     

农杆菌介导的植物遗传转化进展

农杆菌介导的植物遗传转化进展.李子银＠胡会庆.华中农业大学作物遗传改良国家重点实验室农杆菌介导的植物遗传转化进展李子银胡会庆（华中农业大学作物遗传改良国家重点实验室武汉４３００７０）根癌农杆菌（Ａｇｒｏｂａｃｔｅｒｉｕｍｔｕｍｅｆａｃｉｅｎｓ）和发根农杆菌（Ａｇｒｏｂａｃｔｅｒｉｕｍｒｈｉｚｏｇｅｎｅｓ）是两种寄主非常广泛的土壤细菌,在自然状态下它们能通过伤口侵染植物,分别导致冠瘿瘤和毛...     

发根农杆菌及其应用

农杆菌是一类侵染性非常广泛的Ｇ-土壤杆菌,农杆菌质粒介导的基因转移系统是植物基因工程中比较完善与有效的基因转移方法。在众多的转基因植物中有80%是由农杆菌介导转化的,但其中大部分是有根癌农杆菌Ｔｉ质粒介导法获得的。根癌农杆菌含有的Ｔｉ质粒,能诱导被侵染的植物细胞形成肿瘤,即诱发冠瘿瘤。发根农杆菌含有Ｒｉ质粒,侵染植物后能诱发植物细胞产生毛发状根,即发根瘤。近年来的研究发现发根农杆菌Ｒｉ质粒介导法比Ｔｉ质粒法具有一定优越性而被广泛重视,而且由其转化获得转基因植物和生物有效成分的报道愈来愈多,本文主要讨论发根农…     

参与在农杆菌介导遗传转化过程中的植物因子研究进展

随着农杆菌介导遗传转化过程中农杆菌一方转化机理的阐明,人们现在已经将目光转向了参与在农杆菌介导遗传转化过程中的植物因子。应用拟南芥突变体分析,酵母双杂交和cDNA的扩增片段长度多态性等技术人们已经部分阐明了参与在农杆菌向植物细胞的附着,TDNA的加工和转运,T链复合体向细胞核的转运,TDNA的整合等过程中的植物因子,并对植物基因对于农杆菌侵染的响应有了初步的了解。这些结果的获得不仅有助于人们加深对农杆菌介导遗传转化机理的认识而且有助于进一步扩大农杆菌介导遗传转化这一技术的应用范围 。     

发根农杆菌介导的尾巨桉遗传转化体系的建立

发根农杆菌（Agrobacterium rhizogenes）的建立对植物功能基因的验证具有重要意义,为了在桉树（Eucalyptus）中建立发根农杆菌介导的遗传转化体系,本研究以不同的发根农杆菌菌株侵染尾巨桉（Eucalyptus urophylla × E. grandis）的叶片和茎段,确定合适的农杆菌菌株和外植体类型,在此基础上开展农杆菌浓度、侵染时间对毛状根诱导的影响。结果表明：采用发根农杆菌菌株MSU440,以叶片为外植体进行发根诱导,最高获得了81.0%的毛状根诱导率,毛状根平均根长达到3.23 cm。在发根农杆菌浓度为OD₆₀₀=0.3、侵染时间为30 min时,共培养48 h后经过20 mg·L^-1卡那霉素筛选培养,通过PCR分子鉴定和GUS染色证实外源基因稳定地整合在桉树毛状根基因组中,转化率达20.2%。初步建立了发根农杆菌介导的桉树遗传转化体系,为桉树基因功能鉴定和进一步的转基因育种奠定基础。     

Ri质粒介导的毛状根体系建立及其在植物次生代谢产物合成中的研究进展

发根农杆菌Ri质粒可诱导植物产生毛状根体系,该体系具有遗传性状稳定且增殖速度快的特点,可用于药用植物次生代谢产物的生产研究,为利用生物反应器技术进行药用植物有效成分工业化水平的发酵培养开辟了新途径。本文主要综述了发根农杆菌Ri质粒介导的植物毛状根体系遗传转化机理,并对毛状根体系在药用植物次生代谢产物生产中的研究现状进行了深入分析,为从基因水平上调控植物次生代谢产物的合成提供新思路。     

发根农杆菌介导的药用植物遗传转化研究

利用发根农杆菌(Agrobacterium rhizogenes)诱导药用植物产生的毛状根具有生长迅速,合成能力强和遗传性稳定等优点,已成为一种新的培养系统。就影响发根农杆菌介导的药用植物遗传转化的因素作一概述。     

农杆菌介导的植物遗传转化研究进展

农杆菌介导的转基因方法是目前植物遗传转化的重要方法之一。本文从农杆菌转化原理、菌株比较及载体发展入手,系统讨论了植物转化受体对转化效率的影响,同时分别综述了农杆菌介导转化技术在双子叶和单子叶植物转化应用中的最新进展。     

农杆菌介导法与基因枪轰击法结合在植物遗传转化上的应用

根癌农杆菌介导法(Agrohacterium mediated transformation)和基因枪轰击法( particle bombardment transformation)是植物遗传转化的主要方法。两种方法各有优缺点．农杆菌介导法是一种天然的植物遗传转化系统,外源基因在转基因植物中的拷贝数低,遗传稳定性好;基因枪转化法不受材料基因型的限制。通过结合两种方法的优点,发展了3种农杆菌介导和基因枪轰击法相结合的遗传转化方法,分别为农杆枪法、基因枪轰击／农杆菌感染法、金粉或钨粉包裹菌体细胞作为微弹轰击法。对3种结合转化方法的技术途径、原理、转化受体及研究进展等方面进行了综述。     

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.