番木瓜乳管蛋白酶类

番木瓜是著名的热带水果,其乳管中含量丰富的蛋白酶类是近年来研究的一个十分活跃的领域。该文主要介绍番木瓜乳汁中木瓜蛋白酶、木瓜凝乳蛋白酶、蛋白酶Ω和甘氨酰内切酶等4种重要的半胱氨酸蛋白酶及其他蛋白酶类的研究新进展,并对它们的研究与应用前景做了展望。     

21科41种(变种)植物叶片几丁质酶系的研究

对广州地区常见的21科41种（变种）植物叶片几丁质酶系研究的结果表明,所有受试植物都具有几丁质酶活性。几丁质酶不仅存在于被子植物的双子叶植物和单子叶植物中,而且也存在于裸子植物及蕨类植物中。几丁质酶活性及比活性均较高的有蕹菜、葱、蕨类植物、蒜、茄科植物、玉米、菜豆、番木瓜等。植物一般都具有两种几丁质酶:外切酶和内切酶。几丁质外切酶活性及比活性均较高的有蕨类植物、葱、茄科植物等。几丁质内切酶活性及比活性均较高的有蕹菜、裸子植物等。不同植物几丁质外切酶与内切酶的比例相差较大。有些植物的几丁质酶系以外切酶为主,如茄科植物、大部分豆科植物、番木瓜等;有些植物以内切酶为主,如裸子植物、伞形科植物、蕹菜等;有些植物的外切酶与内切酶含量相差不大。     

番木瓜中6个BG生物合成相关基因荧光定量分析

异硫氰酸苄酯(benzyl isothiocyanate,BITC)是医学界公认的具有防癌抗癌活性的成分,对多种癌症具有很好的作用.BG是BITC的前体物质,可以在芥子酶的作用下水解生成BITC.研究表明,BG在热带水果番木瓜中含量丰富.本研究在克隆了番木瓜中6个相关基因和测定了BG在番木瓜不同组织中含量的基础上,采用实时荧光定量PCR技术,对6个基因在番木瓜不同组织中的表达量进行测定,并与BG的含量进行比较,考察其相关性.结果表明各基因的表达量相对较高时BG的含量也较高,即6个基因在番木瓜中的表达量与BG的含量存在相关性.我们推测,这6个基因可能是番木瓜中BG生物合成相关基因.本文结果为进一步研究基因的功能提供了理论依据.     

钾素营养对防治番木瓜叶枯病的影响

对番木瓜叶枯病与植株营养、土壤相关养分的关系等进行研究,结果表明,番木瓜叶枯病是由于土壤有效钾缺乏而导致的一种生理性缺钾症;施用钾肥能有效控制该症的发生并获得较高产量。在发生缺钾叶枯病的番木瓜根、茎、叶片、叶柄等器官中镁含量均明显升高,说明番木瓜植株钾镁间存在拮抗作用。     

番木瓜果糖-2,6-二磷酸酶CpF2KP基因克隆和蛋白表达纯化

番木瓜是岭南四大名果之一,在我国东南部地区广泛种植,因其具有食用和药用双重价值,因此深受人们的青睐。果糖-6-磷酸,2-激酶/果糖-2,6-二磷酸酯酶(fructose-6-phosphate,2-kinase/fructose-2,6-bisphosphatase,F2KP)是一个独特的双功能酶,具有激酶功能域和酯酶功能域,能催化生物体内糖代谢的重要调节物果糖-2,6-二磷酸(Fru-2,6-P_(2))的合成和降解。为了研究番木瓜中编码该酶的基因CpF2KP的功能,得到目的蛋白尤为重要。本研究从番木瓜基因组中提取到CpF2KP基因的编码序列(coding sequence,CDS)序列,该基因CDS全长2274 bp。将该基因CDS全长扩增之后选用pGEX-4T-1载体进行原核表达。对载体pGEX-4T-1用EcoRⅠ和BamHⅠ进行双酶切,利用基因重组的方式将扩增序列构建到原核表达载体上。经过诱导条件探索,SDS-PAGE结果显示GST-CpF2KP重组蛋白的大小约为110 kDa,诱导CpF2KP蛋白表达的最适条件为:异丙基β-D-硫代半乳糖苷(isopropyl beta-D-thiogalactopyranoside,IPTG)浓度为0.5 mmol/L,温度28℃。对诱导后的CpF2KP蛋白进行纯化,得到了纯化的单一目的蛋白。此外,检测了该基因的组织表达特性发现该基因在种子中表达量最高,在果肉中表达量最低。该研究为进一步深入揭示番木瓜CpF2KP蛋白的功能及研究该基因参与的生物学过程提供了重要基础。     

T4转基因番木瓜遗传性和果实品质分析

对T 4代转基因番木瓜进行了分子生物学和果实品质分析,结果表明,筛选获得的转基因番木瓜均为转番木瓜环斑病毒(PRV)复制酶突变体基因(RP),且对PRV抗性达到了高抗或免疫,RP基因在转基因植物中能稳定遗传至后代并在RNA水平上表达。在田间种植时,转基因木瓜的生长状况普遍好于普通番木瓜,尤其在生长后期(10月以后),普通番木瓜100%发病(大规模种植时),而大部分(约91.8%)转基因植株生长良好,果实较多且表面光洁、基本上无环斑。与非转基因亲本相比,T 4代转基因番木瓜的果实长度增加2.6%~5%,果实直径变小0.6%~1.5%,果肉厚度增加了12%~15%,因而果实形状与亲本相近或更好,且信用价值更高。转基因番木瓜果实中水分、蛋白质、氮、脂肪、还原性糖、维生素A、维生素C和类胡萝卜素的含量与对照都无显著性差异,即转基因番木瓜与亲本具有实质等同性,这表明转入的外源基因对番木瓜果实品质没有不良影响。     

番木瓜果实β-甘露聚糖酶提取工艺研究

从番木瓜果实中提取β-甘露聚糖酶,采用分光光度法和凝胶扩散法测定酶活。研究中分别采用不同pH的提取缓冲溶液、不同的番木瓜果实(g)与提取缓冲液的比例(mL)以及在提取缓冲液中添加化合物等体系,得到最佳提取体系为pH 8.0 HEPES-NaOH缓冲液为基本提取液,样品与提取缓冲液的比例为1:3,提取缓冲液中不添加其他化合物。     

转基因番木瓜研究进展

番木瓜环斑病毒 (PRSV)使热带亚热带的重要水果番木瓜的生产受到严重影响 ,在众多方法防效不佳的情况下 ,利用病原获得抗性防治PRSV给番木瓜的生产带来了光明。综述了近年来转PRSVCP基因番木瓜中影响番木瓜转化因素和转基因番木瓜的抗性因素。转PRSV外壳蛋白 (CP)基因的番木瓜中多以胚性组织为转化材料 ,被转化材料的生理状态和基因型 ,是影响转化效率和转基因植株质量的主要因素。所获得的转基因番木瓜对PRSV的抗性在很大程度上依赖于接种PRSV与所转化PRSVCP基因的序列同源性、转基因拷贝数和所转基因的位置等。     

番木瓜性别分化研究进展(综述)

番木瓜性别分化是植物发育生物学的研究热点之一。本文从形态学及细胞学、遗传及基因组、性别分化调控等方面对番木瓜性别分化研究概况进行综述及展望。     

设施栽培下3个品种番木瓜的营养成分分析

测定了引进的3个番木瓜品种在设施栽培条件下,果实的水分、灰分、p H值、可溶性固形物、粗多糖和木瓜蛋白酶活力等6大营养成分的含量,并与海南产番木瓜进行了比较分析。研究结果表明:引进的3个番木瓜品种间灰分、可溶性固形物、木瓜蛋白酶活性具有显著差异,同一品种在不同时期其果实的各项营养指标也具有显著性差别。引进的番木瓜在设施栽培条件下果实的品质均不如海南产的果实。本研究结果为水果之王番木瓜的南果北种提供理论依据。     

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.