茉莉酸和乙烯信号途径参与了油菜菌核病防卫反应

茉莉酸(JA)和乙烯(ET)介导的信号防卫反应在植物抗病性方面具有重要作用。用核盘菌(Sclerotinia sclerotiorum)分别接种甘蓝型油菜(Brassica napus)抗病品种中双9号和感病品种84039,通过荧光定量RT-PCR方法探测JA和ET的关键合成基因及其信号途径标志基因的相对表达水平。结果显示,S.sclerotiorum在这两个品种中都能够诱导这些基因的表达,并且这些基因的相对表达水平在中双9号中显著高于84039;甲基茉莉酸(MeJA)和1-氨基环丙烷-1-羧酸(ACC)的药理学实验结果显示JA和ET信号反应能够相互促进,并且JA和ET信号反应本身存在自我放大的功能。这些结果表明茉莉酸和乙烯信号转导途径参与了甘蓝型油菜菌核病防卫反应。     

茉莉酸调控花药开裂的研究进展

茉莉酸(JA)是广泛存在于植物中的生长调节物质,JA及其衍生物茉莉酸甲酯(Me JA)在植物生命活动中起着重要作用。JA参与调控雄蕊发育,影响花药开裂,从而影响植物育性。就JA的生物合成及相关基因的表达调控、JA在植物花药发育尤其是后期花药开裂过程中相关基因以及信号转导的分子机制研究进行回顾总结,并对JA调控花药开裂的分子机理研究提出展望。     

HDA19调控拟南芥对真菌Botrytis cineara的抗性反应

HDACs(Histone deacetylase)家族蛋白质负责组蛋白H3K4和H4K19脱乙酰化,并参与植物生长和应激反应的信号转导过程。茉莉酮酸酯Jasmonates(JA)是一种重要的天然植物激素,不仅调节植物生长和发育而且还参与植物对多种逆境胁迫响应的信号转导和调控过程。但是,HDACs在植物中参与JA信号转导的具体机制目前还不是很清楚。该研究以HDA19(Histone deacetylase 19)为对象,探讨了HDACs在植物JA信号转导中的功能和作用。结果表明:HDA19的T-DNA插入纯合突变体在JA处理条件下没有出现明显的JA根长反应。在相同处理条件下,hda19的不同突变体株系与相同生态型背景的野生型植株(WT)花色素苷含量无显著差异,但下游JAZ1、VSP1等JA信号通路的标记基因都显著上调表达。同时,hda19相比于WT对真菌Botrytis cineara的抗性显著增强,且hda19中下游基础防御标记基因PDF1.2、Thi2.1、ERF1等的表达水平显著高于WT。基于上述研究结果,该研究认为HAD19通过JA信号通路负调控拟南芥对真菌B.cineara的防御反应。     

植物系统获得性抗性的信号转导

坏死病原菌（necrotizingpathogen）的侵染或者一些化学因子的处理能诱导植物的非侵染或非处理部位产生对多种病原再侵染产生抗性,即系统获得性抗性（systemicacquiredresistance,SAR）。获得系统抗性的组织中SAR基因产物的累积和防卫反应的潜在诱导增强（potentiation）是其两类抗病机制。SAR至少有通过水杨酸（salicylicacid,SA）或茉莉酸（jasmonicacid,JA）、乙烯（ethylene）为系统信号分子的两类信号转导途径。遗传分析已用于SAR产生的信号转导过程的分析,一些与SAR信号转导相关的基因已经和正在克隆,这些基因具有明显提高植物广谱抗性的潜能。     

MAPK和活性氧参与植物抗病防卫反应的信号转导

促分裂原活化蛋白激酶（MAPK）级联途径和活性氧参与调控植物过敏性细胞死亡。本文介绍促分裂原活化蛋白激酶级联途径在植物抗病防卫反应信号转导中的作用研究进展,并对活性氧积累与MAPK之间的关系作了分析。     

高温胁迫及其信号转导

高温是影响当前农业生产重要的不利环境因素之一。本文综述了4种信号分子脱落酸(ABA),Ca2+,水杨酸(SA),茉莉酸(JA)对高温胁迫的响应以及它们的相互关系,高温胁迫能够诱导ABA,Ca2+,SA的含量升高,并且通过外施ABA,Ca2+,SA,JA都能提高植物的抗热性。作为胞内第二信使,外源Ca2+能够提高植物超氧化物歧化酶(SOD),过氧化氢酶(CAT)以及抗坏血酸氧化酶(APX)的活性,且能提高钙调蛋白水平。ABA诱导的抗热性受胞质游离的Ca2+介导。SA被认为是对胁迫反应所必需的信号分子,H2O2很可能是信号转导链的一部分。JA和ABA在生理功能上有很多相似之处,JA独自或通过提高ABA含量来起作用,JA和SA有不同的生理功能,也有相同的(不过它们的信号转导途径可能不同),最后,提出了今后高温胁迫信号转导研究的一些思路。     

激发子诱导植物抗性的作用机制

激发子是能诱导植物任何防卫反应的分子,在原生质膜上存在着其特异高度亲合的蛋白质受体,激发子通过信号识别,信号转导和防卫基因表达调控三个环节诱导植物产生抗病性。     

寡糖激发子对植物防卫反应的诱导

现已发现的生物激发子中除少数是蛋白质或多肽外 ,大多是糖蛋白和寡糖分子。文章对寡糖激发子的种类、信号转导及其对植物防卫反应基因表达调控过程等方面进行了评述     

几丁质酶与植物防卫反应

几丁质酶广泛存在于自然界,亦普遍存在于高等植物中,但在植物体内,至今尚未发现几丁质酶作用的底物。最近的研究不断发现植物防卫反应诱导表达的基因中包含着编码几丁质酶的基因［１］。许多研究已经表明,几丁质酶在植物体内的诱导与积累,对于增强植物防卫能力发挥着重要作用［２］,而植物自身防卫反应是目前植物分子生物学研究的热点之一。本文将着重介绍几丁质酶的特性、诱导及其参与防卫反应的机制的研究进展     

几丁质酶与植物防卫反应

几柄质酶广泛存在于自然界,亦普遍存在于高等植物中,但在植物体内,至今尚未发现几丁质酶作用的底物。最近的研究不断发现植物防卫反应诱导表达的基因中包含着编码几丁质酶的基因。许多研究已经表明,几丁质酶在植物体内的诱导与积累,对于增强植物防卫能力发挥着重要作用,而植物自身防卫反应是目前植物分子生物学研究的热点之一。     

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.