Tn5转座突变技术在革兰氏阴性细菌分子遗传研究中的应用

随着广宿主载体系统的发展,Tn5及其衍生载体已经广泛应用于革兰氏阴性细菌的分子遗传学研究。主要综述了Tn5转座突变技术在生防细菌生防机理研究、细菌必需基因的鉴定、病原细菌毒力相关基因研究、代谢调控基因研究和菌株的遗传改良方面的应用研究进展。     

生防细菌产生的拮抗物质及其在生物防治中的作用

利用生防细菌防治植物病害是生物防治的一个主要内容．生防细菌防治植物病害发生发展的一个重要机制是产生拮抗物质．生防细菌的拮抗物质种类多,作用范围广谱．同一种拮抗物质可以由多种细菌菌株产生,而同一细菌也可以产生多种不同结构的拮抗物质．运用现代分子生物学技术和先进的分析测试手段可以加快对产生拮抗物质生防细菌的研究,了解生防细菌在寄主植物根围和叶围的定植效果。明确拮抗物质在生物防治中的作用．拮抗物质的产生除与细菌基因型有关外,一些外在的生物和非生物因素如病原菌存在与否、温度、pH和C、N营养等也影响拮抗物质产生．文中论述了生防细菌应用中存在的问题。指出混合菌剂的研制对防止病原菌抗性产生具有重要作用,应是今后生防菌剂研制中的重点．     

后基因组时代害虫生防真菌次级代谢产物的研究进展

真菌次级代谢产物在害虫生物防治方面起着重要作用,而其中起杀虫作用的主要活性物质越来越受到人们关注.近几年随着测序技术的发展,利用基因组和生物信息技术挖掘真菌次级代谢产物的方式已成为新的热点,这也为后基因组时代新的真菌生防制剂的发现提供了新的策略.本文先后介绍了几种典型杀虫真菌,阐述了其入侵及致病机制,并对几种常见杀虫真菌所产的杀虫毒素的作用机制进行了介绍,同时也对这些杀虫毒素的生物合成研究进展进行了梳理,为真菌生防制剂的进一步开发提供思路,最后对真菌次级代谢产物在生防制剂方面的应用进行了展望.     

黄瓜花叶病毒卫星RNA生防制剂在烟草上的防病作用

用人工组装的黄瓜花叶病毒卫星RNA生防制剂在烟草生产品种进行了田间保护试验。由于使用了生防制剂,经处理的烟草发病率降低84.9～86.4％,同时比对照早熟5天,上等烟比率增加151.3～173.5％,平均每亩收入增加43.3～65.7％。另外发现生防制剂能增强烟草对真菌病害的抵抗作用。     

生防真菌耐旱特性的生理生化基础及其利用

丝孢类生防真菌常需满足高湿度条件才能萌发和侵染害虫,已成为广泛应用真菌杀虫剂控制害虫的重要限制因素,适当的剂型化技术在一定程度上能够降低菌剂对环境湿度的依赖性,但生防真菌侵染体本身的耐旱性对菌剂的环境适应性起决定性作用,文中回顾和评述了近20多年来国际上生防真菌耐旱性研究与利用的主要进展,分析和总结了生防真菌耐旱性的生理生化基础及其水活度调控原理,讨论了提高低分子多元醇及海藻糖等生物学相容溶质在侵染体内积聚而增强菌剂耐旱性的可能途径．认为认识决定耐旱性的胞内相容溶质积累的分子生物学基础及其调控机理,探索建立从生理生化水平上最大限度地增强生防菌剂耐旱性的新工艺,是今后生防真菌基础与应用研究的重要方向。     

我国生物农药的发展现状

我国生物农药的研究开发始于 5 0年代 ,直到 80年代中期才开始正式列入国家科技攻关的发展计划。近十多年来 ,在生物农药的资源筛选评价、新产品开发、生产工艺、产品质量检测和新技术示范推广方面都取得了长足的进展。目前国内生物农药研究开发的热点 ,主要集中在苏云金芽胞杆菌杀虫剂、农用抗生素杀虫剂、农用抗生素杀菌剂、拮抗细菌生防制剂、昆虫病原真菌制剂和昆虫杆状病毒杀虫剂几个方面。生物农药技术产品开始逐渐走入市场。1　我国生物农药技术产品现状1.1　苏云金芽胞杆菌杀虫剂我国自 5 0年代末开始苏云金杆菌 (简称 Bt)杀虫剂的…     

枯草芽孢杆菌在抑制植物病原菌中的研究进展

枯草芽孢杆菌是芽孢杆菌中比较具应用潜力的菌种之一。近年来国内外对于芽孢杆菌各方面应用的研究日益增多,枯草芽孢杆菌作为一种生防细菌越来越引起人们的关注。主要综述了枯草芽孢杆菌在抑制植物病原菌生物防治领域的研究进展,阐述了枯草芽孢杆菌的控病作用机制,包括竞争作用、拮抗作用、溶茵作用、诱导植物产生抗性及促进植物生长5个方面。简要介绍了枯草芽孢杆菌及其制剂在国内外的应用情况及在植物病害防治应用中存在的问题、解决措施及发展前景。     

植物寄生线虫生防细菌及其作用机制研究

对具有较大潜在应用价值的植物寄生线虫生防细菌的种类、特征和作用方式及其在分子生物学水平上的最新研究进展进行了综述.     

瓜类白粉病的生物防治研究进展

白粉病是危害瓜类作物最为严重的一种气传病害,引起该病的病原菌为单囊壳白粉菌Podosphaera xanthii(synonym Podosphaera fusca)和二孢白粉菌Golovinomyces cichoracearum(synonym Erysiphe cichoracearum),其中对Podosphaera xanthii的报道较为常见。主要概述了瓜类白粉病病原菌的分类地位、病理特征和生物防治方面的研究进展,重点阐述了微生物源生防制剂和植物源生防制剂对瓜类白粉病的防治成果,并对当前研究与应用中存在的问题进行了探讨,为该病的深入研究和有效防治提供参考。     

猕猴桃采后真菌病害生物防治研究进展

猕猴桃果实易受多种病原真菌的侵染,采后易发生软腐病、灰霉病、青霉病等严重危害果实品质的真菌性病害。传统的有效防治方法主要为采前使用化学杀菌剂,但其易污染环境并可能危害人类健康。目前,已有一系列生物防治方法被研究并报道,这些方法可有效防控猕猴桃采后真菌病害：第一类为天然抑菌物质,包括植物提取物和其他天然物质;第二类为拮抗微生物,包括生防酵母、生防细菌、生防木霉,生防菌也能与物理及化学方法协同发挥作用。本文概述了各类生物防治方法在猕猴桃采后真菌病害绿色防控方面的研究进展及生防机理,并提出了目前存在的问题,最后展望了这一领域今后的研究方向。     

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.