丛枝菌根真菌培养方法研究进展

文章结合最新研究成果着重从十个不同的层面对丛枝菌根真菌(AM真菌)的培养方法研究做了较为系统的介绍与评述。认为活体宿主植物盆栽培养法是最简单、最容易、也是最可靠的AM真菌培养方法,玻璃珠分室培养可方便地将培养基质与AM真菌分开,能获得纯净的AM真菌菌体,具有其它方法不可替代的作用,AM真菌单孢无菌的分室Ri T-DNA转型胡萝卜根双重离体培养是获得AM真菌纯净菌体和研究AM真菌遗传、生理、生化等特性的理想方法,以此方法为基础,在根室中补充碳源、在菌丝生长室置换培养基、多次收获菌体的转型根改良双重培养法是提高某些AM真菌孢子产量的力荐方法。     

Arbuscular mycorrhizal fungi enhance the growth of the exotic species Ambrosia artemisiifolia

丛枝菌根真菌促进外来植物豚草的生长 丛枝菌根真菌(AMF)可以通过其菌丝增加寄主植物对养分的吸收,从而促进植物生长。丛枝菌根真菌一直与大多数外来植物的成功入侵联系在一起。然而,有关丛枝菌根真菌如何影响植物入侵成功的机制仍然有待研究。豚草(Ambrosia artemisiifolia)是一种外来的菌根植物。通过长期田间实验,我们研究了种间竞争对豚草和狗尾草(Setaria viridis)根系丛枝菌根真菌多样性和组成的影响。此外,在温室实验中探究了摩西球囊霉(Funneliformis mosseae)对这两种植物生长的影响。研究结果表明,豚草入侵改变了本地植物狗尾草根系丛枝菌根真菌的多样性。另外,豚草根系中摩西球囊霉的相对多度显著高于狗尾草根系中。在田间和温室实验中均发现外来种豚草的丛枝菌根真菌侵染率高于本地种狗尾草。温室实验结果表明,丛枝菌根真菌通过影响豚草的光合能力以及磷和钾的吸收而促进豚草生长。这些研究结果揭示了丛枝菌根真菌和豚草成功入侵之间的重要关系。     

丛枝菌根的双重培养方法及其菌丛际的建立

成功地建立超丛枝菌根真菌Ｇｌｏｍｕｓ ｉｎｔｒａｒａｄｉｃｅｓ与转移Ｒｉ Ｔ－ＤＮＡ胡萝卜根器官的双重培养体系,且在此基础上将根与菌丝分隔开来（两室系统）,在人工培养条件下形成了无杂菌的菌丝际环境。菌丝际的建立为研究菌丝的生理、生化特性奠定了基础。     

多胺对离体培养条件下丛枝菌根真菌生长发育的影响*

研究离体培养条件下多胺 (PUT,SPD,SPM) 及多胺生物合成抑制剂 (MGBG) 对丛枝菌根真菌 (Glomus mosseae, Gigaspora margarita) 孢子萌发特性及菌丝生长发育的影响。试验结果表明,3种多胺类物质在50 ~200g/ml浓度范围内,对丛枝菌根真菌生长发育具显著促进作用,而500礸/ml浓度处理对丛枝菌根真菌生长发育表现强烈的抑制效应。MGBG (50 ~500g/ml) 对丛枝菌根真菌生长发育有较强的抑制作用,且可被外源多胺部分解除,但随浓度升高外源多胺的恢复作用降低,500礸/ml时无效。多胺对丛枝菌根真菌生长发育的促进作用因多胺类型及真菌菌种的变化而有不同的最适浓度范围。作者认为丛枝菌根真菌体内内源多胺的含量也许是其生长发育的限制因子。     

金银花根系VAM真菌侵染过程观察

在金银花生长季节,从西北农林科技大学北校区药用植物园采集金银花根系及根际土壤,采用形态学方法观察研究了VAM真菌侵染其根系的过程,并对其孢子进行了初步的形态学分类。结果表明:(1)VAM真菌侵染金银花根系时,先形成附着胞,然后入侵到皮层细胞,在根内形成线性菌丝、圈状菌丝;菌丝末端产生泡囊;在较粗的菌丝上产生丛枝状菌丝,而且VAM胞内菌丝主干可以穿越相邻的2个皮层细胞,在皮层中连续形成丛枝;VAM菌丝形成丛枝时,首先是胞内菌丝上膨大产生乳状突起,而后在乳状突起上产生较粗的丛枝柄,最后在这些丛枝柄上产生极细的丛枝状菌丝形成成熟的丛枝结构。(2)VAM真菌菌丝在金银花皮层细胞中,有伸展状态、菌丝圈及丛枝状态,所以金银花与VAM真菌形成的菌根是混合型菌根。(3)金银花根际土壤中至少存在3种类型的VAM真菌孢子,因此认为金银花至少可与3种VAM真菌共生。(4)金银花种植地土壤有效磷含量(6.6mg/kg)显著高于对照空地土壤有效磷含量(3.5mg/kg);金银花生长旺盛季(4月下旬到5月中旬)VAM真菌对其根系的侵染率高达81%。     

丛枝菌根利用氮素研究进展

氮素是植物需求量最大的元素,丛枝菌根真菌与植物形成共生体后能从土壤中获取无机氮、简单的氨基酸,还能利用一些复杂的有机态氮.考虑到NH+4在土壤中的移动性低及丛枝菌根真菌的专性共生菌的特点,丛枝菌根真菌吸收NH+4对植物的贡献较大.近年来的研究发现丛枝菌根真菌内存在与氮素代谢有关的鸟氨酸循环,而精氨酸则是菌丝内氮素转移的主要形式.综述最近的AMF对氮素的吸收、转运、同化、交换等方面的文献,旨在揭示丛枝菌根真菌氮素利用特点,阐明丛枝菌根真菌在氮循环系统中的重要作用.     

丛枝菌根共生体中碳、氮代谢及其相互关系

丛枝菌根共生体(arbuscular mycorrhiza, AM)是丛枝菌根真菌(arbuscular mycorrhizal fungi, AMF)与宿主植物之间形成的互惠共生形式.共生体中的碳、氮交换和代谢影响着宿主植物和共生真菌之间的营养平衡和资源重新分配,在物质和能量循环中发挥着重要作用.宿主植物光合固定的碳输送到真菌内,并且分解和释放真菌所需的生命物质和能量,包括促进孢子萌发、菌丝生长和提高氮等营养元素的吸收;而菌根真菌利用宿主植物提供的碳骨架和能量,发生氮的转化和运输,最终传递给宿主植物供其利用.本文综述了丛枝菌根共生体中碳、氮传输和代谢的主要模式,碳、氮的交互影响和调控机制,以促进丛枝菌根在可持续农业和生态系统中的应用.     

几种外生菌根真菌培养特性的研究

对 4种外生菌根真菌的培养特性进行了研究。结果表明 ,PDMA和PD培养基是培养外生菌根真菌的较适合的培养基 ;木屑、麸皮、米糠、玉米粉、蛭石是培养菌根菌菌剂的较适宜的基质 ;用MMN营养液拌料以及适宜的水分供给都有利于外生菌根真菌的生长。     

山珊瑚内生菌根的研究

山珊瑚内生菌根真菌在人工培养基上分离培养不能生长。侵染菌丝由山珊瑚侧根表皮侵入,在皮层中部形成侵染通道。进入皮层细胞后形成丛枝吸器。被侵染的寄主细胞仍是生活细胞,但细胞质变稀,蛋白质、RNA含量很少。近中柱的6至8层皮层细胞壁增厚并木质化。丛枝吸器含有丰富的红淀粉,少量的中性脂肪、碱性蛋白质和D NA。菌丝丛枝干幼龄期电子致密,周围有界面物质包围,在衰老时泡囊化,界面物质亦瓦解。吸器由五边形结构组成。寄主细胞在被侵染前含淀粉质体、线粒体、高尔基体、内质网和核糖体,在被侵染后,淀粉质体消失,其它细胞器数量明显减少,而主要是微丝和小液泡及多泡体。文章讨论了山珊瑚菌根与天麻和泡囊-丛枝菌根的异同。     

珠状巨孢囊霉的单主寄生营养液培养及宿主根分泌物特性*

为研究丛枝菌根真菌对宿主植物根分泌物的影响,在营养液培养条件下成功地建立了菌根真菌Gigaspora margarita与转移Ri T-DNA胡萝卜根器官之间的无菌单主寄生培养方法。接种发芽的孢子四个月后,对根段染色观测,发现萌发孢子的菌丝能够入侵到根段的皮层细胞内,根细胞内有菌丝的折叠卷曲现象,并开始形成了新的孢子。利用高压液相色谱测定各处理营养液中根分泌物的成分,发现菌根分泌的苹果酸和乙酸含量高于对照处理,菌根营养液的pH升高幅度也大于未接种的对照根。     

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.