寡糖对向日葵叶片细胞病程相关蛋白及细胞壁物质的诱导作用

用寡糖对向日葵叶片进行喷雾,研究了该寡糖对向日葵叶片细胞内几丁质酶和β-1,3-葡聚糖酶2种病程相关蛋白(PRs蛋白)以及木质素、富含羟脯氨酸蛋白(HRGP)2种细胞壁物质含量的影响.结果表明,经寡糖处理后,向日葵叶片中β-1,3-葡聚糖酶和几丁质酶的活性均升高,最高值分别比同期CK增加36.38%和6.35%;木质素及HRGP含量也诱导增加,最高值分别比同期CK显著增加39.15%和47.13%.在寡糖处理后接种病原菌的向日葵叶片中,β-1,3-葡聚糖酶及细胞壁物质被诱导合成,且合成量均较单独寡糖处理与单独接种锈菌处理要高.研究发现,诱导向日葵幼苗叶片的几丁质酶、β-1,3-葡聚糖酶活性增强和细胞壁木质素、HRGP含量增加,可能是寡糖预处理增强向日葵抗锈性的内在机制.     

诱抗处理对甜瓜叶片防卫酶活性的影响

以黄河蜜幼苗为材料,分析了化学诱导物处理后甜瓜叶片中几丁质酶(CHI)、β-1,3葡聚糖酶(GLU)、苯丙氨酸解氨酶(PAL)和多酚氧化酶(PPO)活性的变化.结果显示:经5种化学诱导物处理后,甜瓜叶片PAL活性快速增加,于处理后第6天出现活性高峰;苯丙噻二唑(BTH)、水杨酸(SA)、草酸(OAA)和硅酸钠(Na2SiO3)处理后GLU活性变化与PAL相似,PPO活性在测定期内持续升高;磷酸氢二钾(K2HPO4)处理对GLU和PPO活性无明显影响;SA处理后叶片CHI活性明显升高,其它诱导物处理对CHI活性无明显影响.结果表明,防卫酶(特别是GLU和PPO)活性表达增强是BTH、OAA、SA和Na2SiO3等诱导物处理系统诱导甜瓜幼苗白粉病抗性增强的重要生化机制.     

毛头鬼伞多糖对烟草酶活性和同工酶谱的影响

分析了毛头鬼伞(Coprinus comatus)真菌多糖诱导烟草对烟草花叶病毒(TMV)抗性过氧化物酶(POD)、多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)、几丁质酶、-β1,3-葡聚糖酶活性的变化。结果表明,毛头鬼伞多糖可提高POD、PPO、PAL、几丁质酶和-β1,3-葡聚糖酶的活性,接种TMV后毛头鬼伞多糖处理的烟草酶活性显著高于不处理者。上述结果提示,毛头鬼伞多糖处理后烟草酶活性的增强可能与其诱导烟草获得抗性有关。     

核黄素和接种番茄黄化曲叶病毒对番茄叶片防御酶活性的影响

以番茄品种‘1479’为材料,研究了喷施核黄素(Riboflavin)和接种番茄黄化曲叶病毒(TYLCV)对幼苗叶片中过氧化物酶(POD)、多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)3种防御酶活性的影响。结果显示:(1)核黄素能显著降低番茄植株的番茄黄化曲叶病毒病的病情指数,并以2 mmol/L时诱导效果最佳,诱抗效果最高可达41.91%。(2)2mmol/L核黄素处理后96h内,番茄叶片的POD、PPO和PAL活性显著高于对照。(3)接种TYLCV后,核黄素处理和接种TYLCV处理均可诱导番茄叶片中防御酶活性显著增强。研究表明,核黄素处理可诱导POD、PPO和PAL活性的系统增强与番茄对TYLCV的诱导抗性密切相关。     

AM真菌和胞囊线虫对大豆根内酶活性的影响*

将‘鲁豆4号’大豆接种丛枝菌根(AM)真菌聚生球囊霉Glomus fasiculatum和大豆胞囊线虫(SCN)Heterodera glycines 4号生理小种后, 定期测定大豆根系中AM真菌及线虫侵染速率、过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)、β-1,3葡聚糖酶及几丁质酶活性的动态变化。结果表明, 接种AM真菌大豆根系中4种酶活性高于对照水平; 先接种AM真菌后接种SCN处理根系中POD、PAL及几丁质酶的活性高于只接种SCN的处理,并且酶活性峰值出现的时间均早于或相当于后者。另外,PAL及几丁质酶活性出现高峰时期也正是AM真菌侵染率迅速升高及线虫侵染速率快速下降期。因此,AM真菌先激活了大豆的防御反应,然后使其对SCN的侵染产生快速反应,PAL及几丁质酶在AM真菌诱导的抗、耐线虫病害机制中起重要作用。值得注意的是,先接种AM真菌后接种SCN处理大豆根系中,β-1,3葡聚糖酶活性低于只接种AM真菌的处理。作者认为本试验条件下,该酶在大豆抗SCN病害中的作用表现不明显。     

AM真菌和胞囊线虫对大豆根内酶活性的影响

将‘鲁豆4号’大豆接种丛枝菌根(AM)真菌聚生球囊霉Glomus fasiculatum和大豆胞囊线虫(SCN)Heterodera glycines 4号生理小种后, 定期测定大豆根系中AM真菌及线虫侵染速率、过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)、β-1,3葡聚糖酶及几丁质酶活性的动态变化。结果表明, 接种AM真菌大豆根系中4种酶活性高于对照水平; 先接种AM真菌后接种SCN处理根系中POD、PAL及几丁质酶的活性高于只接种SCN的处理,并且酶活性峰值出现的时间均早于或相当于后者。另外,PAL及几丁质酶活性出现高峰时期也正是AM真菌侵染率迅速升高及线虫侵染速率快速下降期。因此,AM真菌先激活了大豆的防御反应,然后使其对SCN的侵染产生快速反应,PAL及几丁质酶在AM真菌诱导的抗、耐线虫病害机制中起重要作用。值得注意的是,先接种AM真菌后接种SCN处理大豆根系中,β-1,3葡聚糖酶活性低于只接种AM真菌的处理。作者认为本试验条件下,该酶在大豆抗SCN病害中的作用表现不明显。     

BTH和SA处理及白粉菌接种对甜瓜叶片光合特性的影响

以抗病品种Tam Dew和感病品种卡拉克赛为材料,研究了BTH和SA处理及白粉菌接种对甜瓜叶片叶面积、叶绿素含量、净光合速率、气孔导度、胞间CO2浓度的影响.结果表明,BTH和SA处理及白粉菌接种对甜瓜苗期叶面积扩展无显著影响;BTH和SA处理植株的叶片(第3叶)和新生叶片(第5叶)的净光合速率、叶绿素含量和气孔导度显著高于对照;白粉菌接种后,2个甜瓜叶片的叶绿素含量、净光合速率和气孔导度显著降低,而BTH和SA处理能缓解由白粉菌接种带来的叶绿素含量、净光合速率和气孔导度的下降趋势.说明BTH和SA处理能延长甜瓜叶片的光合寿命,延缓甜瓜叶片的叶绿素含量、净光合速率和气孔导度的下降趋势.     

纯氧对采后杨梅果实腐烂的抑制与抗病相关酶的诱导

为研究高氧对抑制果实腐烂的作用及其与抗病相关酶活性诱导的关系,将杨梅果实采后在5℃用纯氧或空气(对照)处理12 d.结果表明,纯氧处理可显著抑制果实腐烂发生,贮藏12 d后对照果实的腐烂指数达到54%,而处理果实仅为17%.纯氧处理在贮藏前期可诱导杨梅果实几丁质酶和β-1,3-葡聚糖酶活性的升高,并在第6天时达到高峰.另外,纯氧处理增加了苯丙氨酸解氨酶和过氧化物酶的活性及总酚含量,并在整个贮藏期间一直高于对照水平.这些结果表明,高氧抑制杨梅果实腐烂的作用与诱导与抗病相关的酶的活性升高密切相关,抗病性诱导是高氧抑制杨梅果实腐烂的重要原因.     

甘蓝型油菜几丁质酶基因BnCHB4环境信号响应分析

为了揭示植物激素及环境胁迫对甘蓝型油菜(Brassica napus)几丁质酶基因(BnCHB4)表达的影响。用化学物质苯丙噻重氮(BTH)、甲基茉莉酸(MeJA)、1-氨基环丙烷-1-羧酸(ACC)以及核盘菌(Sclerotinia sclerotiorum)和机械伤害分别处理油菜品种中双9号,采用荧光定量PCR方法测定BnCHB4在各诱导或处理后的相对表达量,结果表明,BTH、MeJA、ACC、S.sclerotiorum和机械伤害都能够快速诱导该基因的表达。表明,BnCHB4是各种环境信号的响应基因。     

植物源诱导剂对甜瓜叶片防卫酶活性的影响

以甜瓜主栽品种‘银帝'(抗病)和‘卡拉克赛'(感病)幼苗为材料,通过盆栽试验研究了几种植物源诱导剂对其接种古巴假霜霉菌叶片过氧化物酶(POD)、多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)、几丁质酶(CHI)和葡聚糖酶(GLU)活性的影响,以阐释植物源诱导剂提高甜瓜抗病性的生化机制.结果显示:苯丙噻二唑(BTH)、侧柏叶提取液(CB)和中草药制剂(ZY)处理对甜瓜霜霉菌具有显著的预防效果;诱导处理或接菌后甜瓜叶片中上述抗病相关酶活性都显著上升,抗病品种‘银帝'的PPO、PAL、CHI、GLU活性增幅大于感病品种‘卡拉克赛',‘卡拉克赛'的POD活性增幅则较‘银帝'大.研究表明,叶面喷施两种植物源诱抗剂对甜瓜叶片防卫酶活性增强具有系统诱导作用,而叶片防卫酶活性增强可能是诱导剂处理后甜瓜对霜霉抗性提高的重要生化机制.     

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.