用免疫荧光单克隆抗体对脊髓灰质炎病毒抗原表位的分析

用间接免疫荧光与中和试验筛选出来的抗脊髓灰质炎2型与3型不同毒株的12个单克隆抗体,其中3个仅有免疫荧光活性,9个具有中和与免疫荧光活性。用免疫荧光活性的单克隆抗体进行试验,发现它们在识别特异性抗原表位方面与中和性单克隆抗体相似,显示出株特异的、几个毒株共同特异的或型特异的抗原表位。根据表位分布关系及特征,可以用来鉴别型内毒株的特征、毒株的抗原分析、抗原变异的研究以及疫苗相关病例的鉴别。所得结果与中和性单克抗隆抗体及T1-寡核苷酸指纹图谱分析一致。而免疫荧光单克隆抗体识别抗原表位的活性范围比中和性单克隆抗体更广。另外还发现某些兼有荧光与中和两活性的同一个单克隆抗体,用不同方法(IF与NT)进行试验时,与相同毒株出现不同表位反应,这点是值得引起注意需待进一步证实的重要问题。     

Induction of anti-EBNA-1 protein by 12-O-tetradecanoylphorbol-13-acetate treatment of human lymphoblastoid cells.

Binding of the Epstein-Barr virus (EBV) nuclear antigen (EBNA-1) to BamHI-C DNA was studied by affinity column chromatography followed by immunoblotting with human serum specific for EBNA-1. Two species of EBNA-1 (68 and 70 kilodaltons) were identified in nuclear extracts of the EBV-positive Burkitt's lymphoma cell line Raji and not in nuclear extracts of the EBV-negative Burkitt's lymphoma cell line BJAB. Both EBNA-1s bound specifically to the region required for EBV plasmid DNA maintenance (oriP) located in the BamHI-C fragment. Upon treatment with 12-O-tetradecanoylphorbol-13-acetate, which activates latent EBV genome in Raji cells, the 68-kilodalton EBNA-1 was uncoupled from binding to EBV oriP. Nuclear extracts from 12-O-tetradecanoylphorbol-13-acetate-treated BJAB cells also uncoupled the binding of both EBNA-1s to oriP. DNA-cellulose column chromatography identified two protein species which competed for and uncoupled the binding of EBNA-1 to oriP. The two cellular competitors we called anti-EBNA-1 proteins had molecular masses of 60 and 40 kilodaltons, respectively. They were not found in nuclear extracts of BJAB cells not activated by 12-O-tetradecanoylphorbol-13-acetate.     

Stable Defined Substrate for Turbidimetric Assay of Endoxylanases

A stable xylan suspension was prepared and characterized. Hydrolysis of the particles converts them into soluble fragments, thereby lowering the turbidity of the suspension. The small volume of the assay mixture, the short incubation time required, and the simplicity of the procedure permit the rapid analysis of many samples. Furthermore, the procedure can be used to assay xylanase activities in the presence of other reducing materials and is also useful for monitoring low-level xylanase activities.     

Intervention trial with selenium for the prevention of lung cancer among tin miners in Yunnan,China

This pilot study evaluated the feasibility and effectiveness of conducting a double-blind clinical trial for the prevention of lung cancer with selenium (Se) in Yunnan Tin Corporation, the People's Republic of China, where the incidence rates of lung cancer are extraordinarily high among the miners. Forty healthy miners were randomized to either 300 μg of Se in high Se malt cakes or an identical placebo of malt cakes daily for one year. Subjects consumed their usual daily diet. The low Se concentrations in plasma (0.05±0.008 μg/mL) and hair (0.442±0.085 μg/g) reflected their low dietary Se intake in the control subjects. In Se-supplemented group, the Se status was increased by 178% for serum and 194.8% for hair. The serum GSHpx activity was increased by 155.7%, whereas the lipid peroxide level was reduced by 74.5% compared to the placebo. The results of UDS assay indicated that the lymphocyte DNA damage induced by ultraviolet irradiation and carcinogen 3,4-benzpyrene could be protected by Se supplementation. Se-supplementation did not affect the liver function test (SGPT), as well as the concentrations of hemoglobin, albumin, and cholesterol. Thus, daily intake of 300 μg Se in form of Se-malt as a chemopreventive measure is safe and effective to humans with low Se status.     

版纳鱼螈和双带鱼螈核型的比较研究

本文对版纳鱼螈的核型作了观察,并与双带鱼螈进行了比较。两者的核型基本一致,均为2n=42,但版纳鱼螈的NF=62,而双带鱼螈的NF=60;版纳鱼螈的染色体有中部着丝粒、亚中部着丝粒和端部着丝粒三种类型,而双带鱼螈则无亚中部着丝粒的染色体。     

中草药“一口钟”的原植物鉴定及其精油的化学成分

云南,四川等省市售的中草药“一口钟”为蓝桉(Eucalyptus globulus Labill.)的果实.用气相色谱-质谱-计算机联用技术、标准品迭加和毛细管保留指数定性法,对其精油的化学成分进行分析.从分离的65个成分中,鉴定出36个成分,其含量占总组成的93.80％,主要成分是别香树烯(23.37％),1.8-桉叶油素(20.81％)、金合欢醇(9.95％)、α-水芹烯(8.30％)、δ-愈创木烯(5.95％)、δ-蒎烯(4.09％)、β-水芹烯(3.43％)、α-愈创木烯(3.15％)等.     

外源脂肪酸及胆固醇对莱氏衣原体膜糖脂含量的影响

 <正> 单葡萄糖甘油二酯(MGDG)和双葡萄糖甘油二酯(DGDG)是莱氏衣原体膜上主要的极性脂。糖脂的生理功能过去很少研究,至今仍不清楚。近年来实验结果表明,MGDG在膜上容易形成六角形Ⅱ结构,而DGDG则形成脂双层结构。六角形Ⅱ结构的出现与生物膜的生理功能的关系是当前瞩目的研究内容。本文首次研究了外源脂肪酸和胆固酵对莱氏衣原体AIH089菌株膜上糖脂含量的影响。     

DNA Segments Sensitive to Single-Strand-Specific Nucleases Are Present in Chromatin of Mitotic Cells

It was observed before that DNAin situin chromatin of mitotic cells is more sensitive to denaturation than DNA in chromatin of interphase cells. DNA sensitivity to denaturation, in these studies, was analyzed by exposing cells to heat or acid and using acridine orange (AO), the metachromatic fluorochrome which can differentially stain double-stranded (ds) vs single-stranded (ss) nucleic acids, as a marker of the degree of DNA denaturation. However, without prior cell treatment with heat or acid no presence of single-stranded DNA in either mitotic or interphase cells was detected by this assay. In the present experiments we demonstrate that DNAin situin mitotic cells, without any prior treatment that can induce DNA denaturation, is sensitive to ss-specific S1 and mung bean nucleases. Incubation of permeabilized human T cell leukemic MOLT-4, promyelocytic HL-60, histiomonocytic lymphoma U937 cells, or normal PHA-stimulated lymphocytes with S1 or mung bean nucleases generated extensive DNA breakage in mitotic cells. DNA strand breaks were detected using fluorochrome-labeled triphosphonucleotides in the reaction catalyzed by exogenous terminal deoxynucleotidyl transferase. Under identical conditions of the cells’ exposure to ss-specific nucleases, DNA breakage in interphase cells was of an order of magnitude less extensive compared to mitotic cells. The data indicate that segments of DNA in mitotic chromosomes, in contrast to interphase cells, may be in a conformation which is sensitive to ss nucleases. This may be a reflection of the differences in the torsional stress of DNA loops between interphase and mitotic chromatin. Namely, greater stress in mitotic loops may lead to formation of the hairpin-loop structures by inverted repeats; such structures are sensitive to ss nucleases. The present method of detection of such segments appears to be more sensitive than the use of AO. The identification of mitotic cells based on sensitivity of their DNA to ss nucleases provides an additional method for their quantification by flow cytometry.     

Selection of large quantities of embryogenic calli from indica rice seeds for production of fertile transgenic plants using the biolistic method

The microprojectile bombardment of immature embryos has proven to be effective in transforming many indica rice varieties. One of the drawbacks of using immature embryos is the requirement of a large number of high quality immature embryos, which itself is a tedious and laborious process. To circumvent these problems, we have developed a procedure, using indica variety TN1 as a model that generates highly homogenous populations of embryogenic subcultured calli by selectively propagating a small number of regeneration-proficient calli derived from seeds. Thousands of embryogenic calli were produced from 50 seeds within 10 weeks. Ten to 20 independent R0 transgenic lines were regenerated per 500 embryogenic calli bombarded. The convenience and reliability offered by this transformation system has made transformation of indica rice a routine procedure.Abbreviations 2,4-D 2,4-dichlorophenoxy acetic acid - NAA naphthalene acetic acid - BAP 6-benzylaminopurine - kb kilobase - GUS -glucuronidase - X-gluc 5-bromo-4-chloro-3-indolyl--D-glucuronide - HPH hygromycin B phosphotransferase     

以异源四倍体体细胞杂种为父本杂交培育三倍体柑桔植株的研究

以 3个柑桔原生质体融合而来的四倍体体细胞杂种为父本 ,与二倍体单胚性种柚子 (Citrusgrandis)以及单多胚混合型品种“华农本地早”桔 (C.reticulata)有性杂交 ,授粉后 90 d,发现种子干瘪 ,大部分种子的胚败育。将干瘪种子在 MT附加 1mg/L GA3 或 50 0 mg/L麦芽浸出物的培养基中 ,经培养抢救 ,有 2 5.6%的种子萌发成苗或继续进行胚的生长 ,后者进一步诱导能形成丛芽 ,经试管嫁接或诱导生根形成完整植株。共获得 6个组合 73棵完整植株 ,染色体数检查表明 ,2 0株为三倍体 (2 n=3x=2 7) ,32株为二倍体 (2 n=2 x=18) ,8株为非整倍体 ,其它 13株还有待于进一步检查。