岑溪药用野生稻高效内生固氮菌分离及促生特性

【目的】以广西岑溪市野生稻保护区的药用野生稻为材料,分离纯化内生细菌,筛选固氮酶活性较高和对作物促生效果较好的菌株。【方法】利用乙炔还原法检测固氮酶活性,采用SDS-PAGE全细胞蛋白电泳和IS-PCR指纹图谱技术对分离到的固氮菌进行聚类。利用16S rRNA基因和nifH基因确定其系统发育地位。采用钼锑抗比色法、Salkowski比色法和CAS检测法分别测定菌株溶磷性、生长素的分泌能力和产铁载体能力。通过平板和盆栽试验检测其对水稻的促生作用。【结果】共分离得到35株内生固氮菌,分为6个类群。其中CX24固氮酶活性最高,经鉴定属于Klebsiella variicola,其固氮酶活性为298.64 μmol/(L·h),为参比模式菌株DSM15968的9倍。另外该菌株还具有较高的溶磷性、分泌生长素和产铁载体能力,能够有效地促进水稻的萌发和生长。【结论】菌株CX24属于Klebsiella variicola,是一株高效内生固氮菌,具有很好的生产应用前景。     

攀枝花地区烤烟可培养内生固氮菌的多样性

【目的】认识烤烟(Flue-cured tobaccos)内生固氮菌多样性,挖掘内生固氮菌资源,丰富内生固氮菌基因库。【方法】运用纯培养法、重复因子扩增(BOX-PCR)分析技术、16S r RNA基因测序和系统发育分析对内生固氮菌多样性和系统发育进行研究,并测定分离菌株的固氮酶活性、溶磷溶钾特性、吲哚乙酸(IAA)含量等指标。【结果】通过Ashby培养基共分离得到62株固氮菌。基于BOX-PCR图谱选取16株代表菌株进行16S r RNA基因序列测定。16S r RNA基因序列系统发育分析显示,62株菌株分属于芽孢杆菌属(Bacillus)、泛菌属(Pantoea)、短小杆菌属(Curtobacterium)等3个属,其中芽孢杆菌属(Bacillus)为优势菌属。62株菌株中有20株菌株(占总分离菌株的32.3%)具有固氮酶活性,8株菌株(占总分离菌株的12.9%)能产IAA,有4株(占总分离菌株的6.5%)表现溶磷活性,有3株(占总分离菌株的4.8%)表现溶钾活性。【结论】攀枝花烤烟有较为丰富的内生固氮菌,具有潜在应用价值。     

藤县药用野生稻内生固氮菌分离鉴定及系统发育分析

从广西梧州市藤县药用野生稻中筛选内生固氮菌,为微生物肥料生产收集菌种资源。采用3种无氮培养基经平板划线法筛选内生固氮菌;通过乙炔还原法测定其固氮酶活性;利用IS-PCR(Insertion sequence-based PCR)指纹图谱和全细胞蛋白电泳图谱对获得的内生固氮菌进行聚类分析;根据16S r RNA基因序列分析确定其进化关系;使用分光光度计比色法检测其产生长素能力、产铁载体能力、溶磷能力和ACC脱氨酶活性。结果显示,从野生稻中筛选获得34株内生固氮菌分为5个类群,类群I和II各有8株,类群III、IV、V分别有2株、5株和11株,其固氮酶活性介于5.0和1 036.7 nmol/(m L·h)之间。类群I代表菌株HU33与无乳固氮螺菌(Azospirillum amazonense ATCC 35119T)相似性为97.13%;类群II代表菌株HU31与变栖克雷伯氏菌(Klebsiella variicola DSM 15968T)相似性为99.71%;类群III代表菌株HU17与蒙氏假单胞菌(Pseudomonas monteilii ATCC 700476T)相似性为99.86%;类群IV代表菌株HU13与黄黄色杆菌(Xanthobacter flavus ATCC 35867T)相似性为100%;类群V代表菌株CM05与越南伯克霍尔德菌(Burkholderia vietnamiensis LMG 10929T)相似性为99.86%。药用野生稻内生固氮菌资源具有遗传多样性;有些菌株有较强的产生长素、产铁载体、ACC脱氨酶活性和溶磷能力,在农业生产上具有一定的应用潜力;类群I可能是一个新类群。     

一株水稻根内生拮抗细菌SM13的分离及鉴定

【背景】作物根内生细菌具有固氮、分泌激素、产生病原真菌抗性物质等特性,根系内生菌的分离及应用成为环境友好型防控技术研究的热点之一。近年来盐碱地水稻种植面积逐年增加,而关于盐碱地水稻根内生菌的分离与应用鲜有报道。【目的】从大庆盐碱地水稻根中分离内生细菌,筛选对植物真菌病害有拮抗作用的促生菌株,初步探讨其抑菌和促生功效,为进一步研究其抑菌和促生机理提供菌种资源。【方法】对水稻根表面灭菌后研磨涂布分离内生细菌,采用对峙培养法和改良Salkowski比色法筛选具有广谱抑菌效果并有分泌吲哚-3-乙酸(Indole-3-acetic acid,IAA)能力的菌株,通过形态鉴定、革兰氏染色、生理生化测定、16S rRNA结构基因以及srfA、ituA、fenB功能基因序列系统进化分析,确定细菌的分类地位。【结果】从水稻根部分离到一株内生细菌SM13,该菌株具有广谱性抑菌作用,对玉米新月弯孢菌、大豆菌核病菌、稻瘟病菌、禾谷镰刀菌的抑菌率分别为59.38%、78.13%、53.12%、37.50%,分泌IAA的能力为5.56±0.41μg/mL (n=6)。经形态学、生理生化试验结合系统进化分析初步鉴定SM13菌株属于枯草芽孢杆菌(Bacillus subtilis),该菌株在pH 11.0、盐浓度10%的NA培养基中生长良好,具有较高的耐盐碱性。【结论】水稻根内生菌SM13菌株具有耐盐碱性、促生和生防性能,可作为微生物农药及菌肥的材料。     

辣椒镰孢根腐病防病促生细菌的筛选及其效应

【目的】筛选辣椒(Capsicum annuum L.)根腐病防病促生细菌并明确其防病促生效应。【方法】采集健康辣椒根围土壤样品,以辣椒根腐病病原真菌茄镰孢(Fusarium solani)和尖镰孢(Fusarium oxysporum)为指示菌,采用平板对峙法筛选生防细菌,采用选择性培养基筛选溶无机磷、溶有机磷、固氮菌和解钾菌等促生菌,钼锑抗比色法测定溶磷量,凯氏定氮法测定固氮量,火焰原子吸收光谱法测定解钾量。对特性良好组合的菌株进行16S rDNA序列分析鉴定并制作菌剂,最后采用盆栽法测定菌剂防病促生效果。【结果】共筛选得到323株特性良好的功能菌株,拮抗菌78株,溶有机磷菌87株,溶无机磷菌107株,固氮菌128株,解钾菌123株,部分菌株同时具有多个功能特性。互作组合得到6个特性良好的菌株组合,包括8株功能菌株,鉴定发现XP271和XP181为枯草芽胞杆菌(Bacillus subtilis),XP125为特基拉芽胞杆菌(Bacillus tequilensis),XP236为耐盐芽胞杆菌(Bacillus halotolerans),XP79为巨大芽胞杆菌(Bacillus ...     

水稻内生固氮菌Herbaspirillum seropedicae DX35的筛选及其促生特性

【目的】筛选水稻高效内生固氮菌,并对其促生特性进行分析。【方法】从湖南祁阳中国农业科学院红壤实验站具30年长期稻-稻-绿肥轮作定位试验田中采集水稻根并分离内生细菌,通过乙炔还原法测定其固氮酶活性,筛选出固氮活性较高的菌株,运用16S rRNA基因、nifH基因以及脂肪酸分析确定其发育地位。同时采用Salkowski比色法测定其生长素的分泌能力,CAS蓝色平板检测法测定产铁载体能力,溶磷圈法测定溶磷性,对其促生特性进行分析。【结果】共分离获得48株内生菌,其中DX35固氮酶活性最高,经鉴定属于Herbaspirillum seropedicae,其固氮酶活性为181.21 nmol C2H4/(mg protein·h),约是参比菌株Azotobacter chroococcum ACCC10006的10倍。另外该菌株还具有一定的分泌铁载体能力和溶磷特性。【结论】DX35属于H.seropedicae,是一种高效内生固氮菌,具有很好的生产应用前景。     

水稻内生固氮菌Herbaspirillum seropedicae DX35的筛选及其促生特性

摘要:【目的】筛选水稻高效内生固氮菌,并对其促生特性进行分析。【方法】从湖南祁阳中国农业科学院红壤实验站具30年长期稻-稻-绿肥轮作定位试验田中采集水稻根并分离内生细菌,通过乙炔还原法测定其固氮酶活性,筛选出固氮活性较高的菌株,运用16S rRNA基因、nifH基因以及脂肪酸分析确定其发育地位。同时采用Salkowski比色法测定其生长素的分泌能力,CAS蓝色平板检测法测定产铁载体能力,溶磷圈法测定溶磷性,对其促生特性进行分析。【结果】共分离获得48株内生菌,其中DX35固氮酶活性最高,经鉴定属于Herbaspirillum seropedicae,其固氮酶活性为181.21 nmol C2H4/(mg protein·h),约是参比菌株Azotobacter chroococcum ACCC10006的10倍。另外该菌株还具有一定的分泌铁载体能力和溶磷特性。【结论】DX35属于H.seropedicae,是一种高效内生固氮菌,具有很好的生产应用前景。     

水稻促生菌的筛选、鉴定及其促生效果

【背景】微生物在促进水稻生长上潜力巨大,利用水稻促生微生物是减少水田化肥施用、保障水稻安全高效生产的有效途径之一。【目的】筛选并获得能显著促进水稻生长的微生物,为水稻微生物肥料提供优质菌种资源。【方法】从水稻根围微生物中筛选具有高效固氮、溶磷、解钾、产铁载体和吲哚乙酸(indole acetic acid,IAA)的微生物菌株,并对其进行初步鉴定,分析其对水稻种子萌发和植株生长的影响。【结果】从394株水稻根围细菌中筛选并获得了6株在固氮或溶解有机和无机磷、钾或产铁载体和IAA综合水平较高的菌株,分别为菌株C7-1、L26、C10-19、S11-11、GYM＿bt5和20-10,根据16SrRNA基因序列初步鉴定这些菌株为嗜线虫沙雷氏菌(Serratia nematodiphila)、阿耶波多氏芽孢杆菌(Bacillus aryabhattai)、别氏不动杆菌(Acinetobacter bereziniae)、蒙氏假单胞菌(Pseudomonas monteilii)和贝莱斯芽孢杆菌(Bacillus velezensis)。促生试验结果表明,除别氏不动杆菌C10-19外,其他5株菌...     

落地生根内生固氮菌多样性和促生特性

【背景】内生固氮菌可以定殖于植物体内为植物提供营养物质,还能通过代谢促进植物生长,目前对于落地生根内生菌的研究鲜见报道。【目的】研究落地生根中内生固氮菌多样性。【方法】从表面消毒的植物组织中分离纯化内生菌,并通过乙炔还原法测定菌株的固氮酶活性。采用SDS-PAGE全细胞蛋白电泳和IS指纹图谱对菌株聚类,各类群代表菌株进行16S rRNA基因系统发育分析和生理生化鉴定。测定菌株固氮、分泌生长素和ACC脱氨酶、产铁载体、溶磷和解钾等促生特性。【结果】从落地生根中分离纯化出26株内生固氮菌,聚为5个类群,隶属于4个属的5个菌种,且各类群代表菌株具有多种促生功能。【结论】从落地生根中分离获得的内生菌具有丰富的遗传多样性和促生特性,并且存在新的微生物资源,有待开发利用。     

高秆野生稻内生固氮细菌多样性

高秆野生稻(Oryza alta)是一种重要的种质资源, 其组织内也蕴藏着非常宝贵的功能微生物资源。本实验采用无氮培养基, 从高秆野生稻中分离到43株内生固氮菌, 结合乙炔还原法测定其固氮酶活性。经固氮酶基因(nifH)的PCR扩增检测, 43株内生固氮菌代表菌株均能扩增出固氮酶基因片段。利用IS-PCR DNA指纹图谱和SDS-PAGE全细胞蛋白电泳图谱将获得的菌株聚类为6个类群(I、II、III、IV、V、VI)。对各个类群的代表菌株(ZF3, ZF8, ZF13, ZF15, ZF24, ZF43)进行16S rRNA基因序列测定, 结果表明, 类群I属于土生拉乌尔菌(Raoultella terrigena), 类群II属于类肺炎克雷伯氏菌类肺炎亚种(Klebsiella quasipnmoniae subsp. quasipneumoniae), 类群III属于越南伯克氏菌(Burkholderia vietnamiensis), 类群IV的菌株代表肠秆菌属的一个类群(Enterobacter sp.), 类群V的菌株属于门多萨假单胞菌(Pseudomonas mendocina), 类群VI归属于固氮植物菌(Phytobacter diazotrophicus)。Biolog聚类结果与IS-PCR指纹图谱类型及SDS-PAGE全细胞蛋白聚类结果一致。Biolog板测定结果显示, 来自不同类群的代表菌株对碳源的利用差异显著, 说明野生稻内多样的内生固氮菌从环境中获取碳源和氮素的适应能力较强。     

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.