褐飞虱成虫不同密度和取食时长胁迫下水稻植株的生理生化响应

【目的】探索褐飞虱Nilaparvata lugens不同密度与取食时长胁迫下水稻植株生理生化响应。【方法】在褐飞虱成虫3个密度(2,4和8头/株)与4个取食时长(6, 24, 48和96 h)的组合处理后，应用生物化学分析方法检测水稻植株中叶绿素(chlorophyll, Chl)与总蛋白(total protein, TP)含量，脂氧合酶(lipoxygenase, LOX)、总超氧化物歧化酶(total superoxide dismutase, T-SOD)、过氧化物酶(peroxidase, POD)与多酚氧化酶(polyphenol oxidase, PPO)活性。【结果】与对照组(未接种褐飞虱成虫)相比，取食6 h时，低密度(2头/株)褐飞虱成虫引起水稻植株中Chl含量显著降低，TP含量和PPO活性显著升高；高密度(8头/株)褐飞虱成虫引起水稻植株中Chlb和总Chl含量、TP含量及LOX和POD活性显著升高。与对照组相比，取食24 h时，低密度褐飞虱成虫引起水稻植株中Chl含量和PPO活性显著降低，LOX, T-SOD和POD活性显著升高，高密度褐飞虱成虫引起水稻植株中...     

烟草FLS基因表达抑制对类黄酮代谢的影响

高等植物中黄酮醇合成酶催化二氢黄酮醇转化生成黄酮醇,是类黄酮代谢途径的关键酶之一。本研究在烟草基因组数据库中搜索获得两个类黄酮合成酶基因,即NtFLS1和NtFLS2,二者表达模式一致,均在叶片中高水平表达。在NtFLS2基因过表达载体的转化株中获得一个共抑制株系KD36,荧光定量PCR分析表明NtFLS1和NtFLS2基因表达水平均被显著抑制,类黄酮途径其它结构基因的表达水平未发生显著变化。KD36株系中二氢槲皮素含量显著上升,是对照的12倍,槲皮素、山奈酚、二氢山奈酚含量未发生显著变化。KD36株系花色更红,花青素含量是对照植株2.4倍。上述研究揭示了烟草黄酮醇合成酶基因的功能,为进一步研究烟草类黄酮代谢提供了一定的理论依据。     

烟草在PVYN病毒与烟蚜作用下对高CO2浓度的响应

以CO2浓度为主处理因子,研究了加倍CO2浓度和对照大气CO2浓度条件下,烟蚜、马铃薯Y病毒N株(PVYN)以及二者共同作用下烟草各指标的响应。结果表明,在当前CO2浓度条件下,PVYN、烟蚜及两者联合作用对烟草生物量影响不显著;而在未来高CO2浓度条件下,PVYN、烟蚜及两者联合作用对烟草生物量影响很大。CO2浓度升高后,PVYN和蚜虫二者联合作用显著降低烟草产量,危害加重,高CO2的"肥料"作用被极大地削弱。在有烟蚜、PVYN以及两者共同作用时烟草的化学物质及主要的次生代谢物烟碱的含量对CO2浓度升高的响应也发生一定的变化,表现在:高CO2浓度条件下,蚜虫、蚜虫与PVYN共同作用显著增加了烟草的含氮量;显著减少了烟叶含糖量;PVYN及其与蚜虫共同作用显著升高叶片可溶性蛋白含量;当高CO2浓度下,各处理的烟草烟碱含量均显著下降,而且PVYN感染的烟叶烟碱含量无论在哪一种CO2浓度条件下,都比无毒无虫的对照烟叶烟碱含量升高。结果显示,烟蚜和马铃薯Y病毒N株(PVYN)对烟草的产量、营养物质及防御物质都有影响;CO2浓度升高对烟草的生长有促进作用,增加了烟草的产量,但蚜虫的危害和PVYN感染使烟草产量下降,在高CO2浓度条件下,烟蚜和PVYN共同作用相对于目前CO2浓度对烟草产量的危害加重。     

超量表达MrCN基因提高烟草植株对TMV的抗性

利用农杆菌介导的遗传转化法将含有普通烟草Ubi．U4启动子驱动MrCN基因表达的元件导入TMV敏感烟草品种K326中,对筛选鉴定出的T0代转基因植株接种TMV,测定其接种前后不同时期的理化指标,以接种TMV的野生型植株为对照。结果显示,转基因植株和野生型植株接种TMV前叶绿素（Chl）和MDA含量YLSOD、POD和CAT酶活力均无显著差异,但接种TMV后野生型植株Chl含量逐渐降低,转基因植株Chl含量先增后降,在接种TMV后5d时转基因植株叶片Chl含量显著高于野生型植株。接种前期（0-3d）转基因植株MDA含量略低于野生型植株,但差异不显著;但接种后期（3～5d）前者的MDA含量显著低于后者。接种TMV后转基因植株中SOD、POD及CAT酶活性变化幅度较野生型植株高,以CAT的变幅最为显著。另外,Real-timePCR分析结果表明,接种TMV后3d时转基因植株删蹦、PR-1α及NrCN表达量均显著高于野生型植株。以上结果表明,通过转基因技术提高烟草抗病基NNrCN的表达量,能提高防御酶活性及病程相关基因的表达量,从而延缓植株感染TMV的发病时间,增强敏感植株对TMV的抗性。     

超量表达NrCN基因提高烟草植株对TMV的抗性

利用农杆菌介导的遗传转化法将含有普通烟草Ubi.U₄启动子驱动NrCN基因表达的元件导入TMV敏感烟草品种K326中,对筛选鉴定出的T₀代转基因植株接种TMV,测定其接种前后不同时期的理化指标,以接种TMV的野生型植株为对照。结果显示,转基因植株和野生型植株接种TMV前叶绿素（Chl）和MDA含量及SOD、POD和CAT酶活力均无显著差异,但接种TMV后野生型植株Chl含量逐渐降低,转基因植株Chl含量先增后降,在接种TMV后5 d时转基因植株叶片Chl含量显著高于野生型植株。接种前期（0³ d）转基因植株MDA含量略低于野生型植株,但差异不显著;但接种后期（3⁵ d）前者的MDA含量显著低于后者。接种TMV后转基因植株中SOD、POD及CAT酶活性变化幅度较野生型植株高,以CAT的变幅最为显著。另外,Real-time PCR分析结果表明,接种TMV后3 d时转基因植株MAPK、PR-1a及NrCN表达量均显著高于野生型植株。以上结果表明,通过转基因技术提高烟草抗病基因NrCN的表达量,能提高防御酶活性及病程相关基因的表达量,从而延缓植株感染TMV的发病时间,增强敏感植株对TMV的抗性。     

菠萝叶片色泽、色素及抗氧化活性的关系

以菠萝22个栽培品种的叶片为实验材料,测定其5种色泽参数（L^*、a^*、b^*、c^*和h^*值）、5种色素（叶绿素、类胡萝卜素、花青苷、类黄酮和总酚）含量及3种抗氧化活性指标（ABTS、DPPH自由基和亚硝酸盐的清除能力）,并进行相关性分析。研究结果显示,色泽参数a^*和h^*值可以作为菠萝叶片指示色泽、主要色素含量和抗氧化活性变化的重要指标;菠萝叶片主要色素组成是叶绿素、类黄酮和总酚,且含有少量的花青苷,几乎不含类胡萝卜素。相关性分析结果显示,菠萝叶片类黄酮和总酚含量均与3种抗氧化活性指标极显著正相关,而叶绿素含量与其它指标相关性未达到显著水平,类黄酮和总酚是菠萝叶片抗氧化活性的主要功效成分。     

百合查尔酮合成酶基因克隆及其转化烟草的花色表达分析

以‘西伯利亚’百合为试材,利用PCR技术克隆了查尔酮合成酶基因(CHS),构建了CHS基因的正义和反义植物表达载体,采用农杆菌介导法转化烟草叶盘,获得了转正义CHS基因的本明烟草18株,转反义CHS基因的普通烟草21株,总转化率为26.0%。高效液相色谱法(HPLC)检测结果显示,正义CHS转基因的本明烟草类黄酮含量升高14.0%～59.7%,反义CHS转基因的普通烟草类黄酮含量降低44.5%～76.4%。花色观察结果显示,正义转基因烟草的花瓣颜色未见变化,反义转基因烟草部分植株的花瓣颜色变浅。研究表明,CHS基因遗传转化是进行花色调控的有效手段之一。     

营养元素与烟草的品质和产量

烟草是叶用经济作物。营养元素对烟叶产量、品质的影响很敏感。烟草所需的营养元素,现已查明有70余种,其中必需的元素有氮、磷、钾、钙、镁、氯、硼、锰、硫、锌、铜等,有些元素虽然需要量甚微,但不可缺少,不可代替。如若缺少某一种元素,植株就不能正常地生长发育、开花、结实,甚至死亡。现就上述主要元素,对烟草产量、品质的影响进行微浅的论述,以提出较为合理的耕作栽培施肥方法。 烟草的必需元素 1.氮(N)氮是影响烟株生长发育、烟叶质量的主要元素。氮是蛋白质、叶绿素、核酸、磷脂和酶的成分,在植物生命活动中占有特殊地位,被称为“生命元素”。     

铜胁迫条件下AMF对海州香薷光合色素含量、抗氧化能力和膜脂过氧化的影响

以盆栽海州香薷为研究对象,模拟Cu胁迫条件下,接种丛枝菌根真菌(AMF)对海州香薷叶片光合色素含量、抗氧化酶活性、抗氧化剂含量、膜脂过氧化程度的影响。结果表明:(1)与对照相比,Cu胁迫使海州香薷叶片叶绿素a(Chl a)、叶绿素b(Chl b)、总叶绿素(Chl(a+b))、类胡萝卜素(Car)含量以及叶绿素a/b(Chl a/b)均显著降低,抗氧化酶活性和抗氧化剂含量也显著下降,质膜相对透性(MRP)和丙二醛(MDA)含量显著增大。(2)与Cu胁迫相比,Cu胁迫下接种AMF可使海州香薷叶片叶绿素含量显著增加;超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)活性显著提高;还原型谷胱甘肽(GSH)、抗坏血酸(As A)含量显著增加;MDA含量、MRP显著下降。总之,接种AMF可提高Cu胁迫下海州香薷叶片光合色素含量和抗氧化能力,降低膜脂过氧化水平,从而缓解Cu胁迫对植株造成的伤害,增强海州香薷对Cu胁迫的适应性,提高了植株的生物量。     

黄瓜花叶病毒和烟草花叶病毒在双抗转基因线辣椒内的增殖

本试验以转化CMV-CP和TMV-CP基因的转基因线辣椒纯合系植株作为研究试材,比较了单独 或混合接种CMV和TMV后,转化线辣椒的抗病性表达特点,并测定了两种病毒在植株体内的病 毒含量.结果表明转化线辣椒不仅能抵抗CMV和TMV的单独侵染,而且还能抵抗CMV和TMV的 复合侵染.转化线辣椒表现为系统症状延迟出现7-15d,显症株率和病害严重度级别大幅度降低, CMV和TMV在接种叶、新生叶中的病毒含量明显减低.转基因线辣椒原生质体作为研究试材接 种CMV,测定病毒含量结果表明CMV病毒的增殖在转基因线辣椒原生质体内受到明显抑制. 在CMV接种浓度为40μg/mL,感染原生质体48h后,CP(-)植株原生质体内CMV是CP(+)的4.2倍 .这一结果揭示了转基因线辣椒具有抑制病毒增殖的抗病性.     

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.