外源甜蛋白thaumatin II基因转入烟草的研究

利用土壤农杆菌系统,将高甜度的外源甜蛋白thaumatin II基因转入烟草细胞,并得到大量转基因植株及其后代。经分子杂交分析确证thaumatin II基因已整合到烟草植株的基因组中,并在转录水平检测到表达。标记基因胭脂碱合成酶(NOS)基因及新霉素磷酸转移酶(NPT II)基因也在转基因植株中正常表达。     

人工合成的纳豆激酶基因转化烟草的研究

根据植物偏爱密码子人工合成的纳豆激酶基因sNK和其中插入番茄果实特异表达基因E8第一内含子的纳豆激酶基因sNK-E8i,通过农杆菌侵染的方法转化到烟草NC89中。经PCR检测,得到12株转sNK基因烟草植株和10株转sNK-E8i基因烟草植株,初步证明目的基因已整合到烟草基因组中;RT-PCR检测有9株转sNK基因烟草植株和10株转sNK-E8i基因烟草植株为阳性;通过RT-qPCR将两种基因在烟草中的表达量进行比较,结果表明转sNK-E8i基因的植株中纳豆激酶的表达量比转sNK基因的植株中高;通过纤维蛋白平板法检测其活性,共有5株转sNK基因烟草植株和3株转sNK-E8i基因烟草植株检测到溶圈,说明目的基因在部分转基因烟草中可正常转录和翻译并表现出溶栓活性。经加代培养已得到T1代转基因植株。     

铁皮石斛DoSMT2基因的功能分析

为了揭示铁皮石斛(Dendrobium officinale)甾醇C-24甲基转移酶2基因(DoSMT2)在甾醇代谢过程的功能,该研究通过根癌农杆菌介导法将来源于铁皮石斛的DoSMT2基因转化烟草(Nicotiana tabacum),并采用qRT-PCR技术检测DoSMT2基因在转基因烟草叶片中的表达,采用气相色谱质谱法分析菜油甾醇和谷甾醇的含量。结果显示:(1)成功获得DoSMT2基因的开放阅读框(1 119 bp),并成功构建正义植物表达载体质粒pCXSN-DoSMT2,经农杆菌介导的烟草叶盘转化法转化烟草并鉴定,获得4株阳性转基因烟草植株。(2)Southern blot结果表明,4株转基因烟草植株都有1条杂交信号带,而非转基因烟草植株没有,说明外源DoSMT2基因都以单拷贝整合到4株转基因烟草基因组中。(3)qRT-PCR检测显示,非转基因烟草未检测到外源DoSMT2基因的表达,4株转基因烟草都能检测到DoSMT2基因的表达,且表达水平差异极显著,各株系表达量高低依次为P3P1P2(P4)。(4)气相色谱质谱分析显示,转DoSMT2基因烟草叶片的菜油甾醇含量均极显著低于非转基因烟草叶片,而谷甾醇含量均极显著高于非转基因烟草叶片。研究表明,DoSMT2具有催化24-亚甲基胆甾烯醇转化形成24-亚乙基胆甾烯醇活性。     

表达β-1,3-葡聚糖酶及几丁质酶基因的转基因烟草及其抗真菌病的研究

利用烟草碱性β－１,３－葡聚糖酶及菜豆碱性几丁质酶基因构建了组成型表达的双价植物表达载体ｐＢＬＧＣ,利用农杆菌介导法转化了烟草,并得到了转基因植株。对其进行分子生物学分析的结果表明,部分转基因植株在所有检测中都显示较强的阳性反应,这说明外源基因已整合到烟草基因组中得到正确表达。活体接菌实验初步表明,转基因植株与对照相比,对赤星病的侵染具有较强的抵抗能力。     

iaaL基因在烟草绒毡层中的特异表达对花粉胚胎发生的影响

来源于丁香假单孢杆菌的吲哚乙酰胺赖氨酸酯合成酶(indoleacetic acid-ly-sine synthetase)基因(iaaL)与来自烟草的在花药绒毡层特异表达(tapetal-specific)的启动子TA29融合后导入烟草,在转基因烟草中研究了这种嵌合基因的表达特性,并测定了各器官内源生长素水平.结果表明:TA29启动子只能启动iaaL基因在转基因植株的花药中特异表达,并导致转基因植株花药内源IAA含量的下降,但在完整植株上并没有对花药的正常发育造成明显的影响.当转基因植株的花药在不附加任何激素的改良Nistch H(NH)培养基上培养时,花粉胚胎发生频率下降至11%(对照在50%以上);当在NH培养基上补加0.2mg/L IAA时,转基因植株的花粉胚胎发生频率恢复到与对照相当(达55.7%),由此说明花药绒毡层细胞中IAA的代谢对花药培养中花粉胚的发育具有重要的意义.     

Pttkn1基因异位表达对烟草叶片形态的影响

以红花烟草(Nicotiana tabacum L.)叶片为材料,利用农杆菌介导的叶盘转化法将Pttkn1基因整合到烟草基因组中,获得了转基因植株,研究了该基因对植物形态发生和维管形成的影响,并对其进行了RT-PCR分析。结果表明,转基因烟草植株的叶片形态和叶脉发生了多种变化,包括叶片对称性丧失、出现裂片、皱缩、异位茎、杯状叶片、瘤状结构、叶脉脉序紊乱等。RT-PCR分析表明,该基因仅强烈表达于转基因烟草植株中,而在野生型和组织培养材料中均未检测到该基因的存在。表明Pttkn1基因已经成功转入烟草中,而且在叶片形态发生和维管形成过程中发挥一定的作用。     

无苞芥锌指蛋白基因OpZFP提高烟草耐盐性的研究

旨在研究C2H2型锌指蛋白在植物生长发育、非生物胁迫信号转导过程中的作用。前期从新疆无苞芥中克隆的一个单锌指基因Op ZFP,利用叶盘法将Op ZFP基因转入普通烟草中。半定量RT-PCR表明,在转基因植株中Op ZFP基因能够高效表达。烟草耐盐性分析显示,在高盐胁迫下,转基因植株的根长要长于野生型植株,且转基因烟草丙二醛(MDA)的含量要明显低于野生型植株;并且高盐胁迫处理,野生型烟草离体叶片叶绿素降解率高于转基因植株。这些结果表明,过量表达Op ZFP的转基因植株可以提高植物对盐胁迫的抗性。     

甜味蛋白thaumatin基因转入烟草的研究

利用基因工程技术,将分别克隆在两个不同载体上的甜味蛋白thaumatin cDNA基因片段连接成一个完整的cDNA基因,并将该基因克隆进pBI121,构建成表达载体pBI121-tha。通过冻融法导入农杆菌,农杆菌介导叶盘法转入烟草,经过组培,得到转基因的植株。提取转基因烟草总DNA,经PCR,PCR—Southern和Southern杂交证实,甜味蛋白基因已整合到烟草基因组中。RT—PCR结果证明,thaumatin基因已在转基因烟草中转录成mRNA,但SDS—PAGE和甜味尝试都表明thaumatin基因在转基因烟草中没有表达出甜味蛋白。     

转石蒜凝集素基因烟草的抗蚜虫性

利用农杆菌介导法将质粒pBILRA转化烟草(NicotianatabacumL.),该质粒含有由花椰菜花叶病毒35S启动子(CaMV35S)引导的筛选基因新霉素磷酸转移酶基因(nptII)及石蒜凝集素基因(lra)。通过卡那霉素筛选获得了25株独立转基因烟草植株。Westernblot分析表明,石蒜凝集素蛋白在不同转基因植株中表达量不同。对转基因T1代植株的遗传分析表明,lra基因在大多数独立转基因植株后代中以孟德尔31的分离比方式遗传。抗虫试验表明,表达较高水平石蒜凝集素蛋白的转基因烟草对桃蚜种群的生长具有明显的抑制作用。首次报道了表达石蒜凝集素基因的烟草对蚜虫具有抗性。石蒜凝集素基因可用于植物抗虫基因工程研究及应用。     

转油菜素内酯合成基因DET2烟草对NaCI胁迫的反应

通过农杆菌介导法,将含有油菜素内酯合成基因DET2的植物表达栽体pCAMBIA2301-DET2转入烟草,获得转基因烟草植株.用T1代转基因阳性株进行耐NaCl试验,结果显示,NaCl胁迫下转基因烟草、非转基因对照烟草的出苗率、幼苗鲜重、株高及根长均随NaCl浓度增加而下降.但在相同NaCl浓度下,转基因植株鲜重、株高及根长均明显高于非转基因对照烟草,并且转基因植株的丙二醛( MDA)含量低于非转基因植株,诱导蛋白基因P5CS表达高峰出现时间晚于非转基因植株.说明DET2的表达提高了烟草的耐NaCl能力.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

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.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

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