几种榕属(Ficus)植物标本的DNA提取及PCR扩增

植物标本作为一种非常重要的DNA资源受到越来越多的关注.由于其储存时间久远及储存手段局限,使得植物标本DNA提取和扩增相当困难.本研究以桑科榕属的9个种作为研究对象,采用4种DNA提取方法,比较其产物的数量和质量,并将所提取的DNA作为模版进行PCR扩增ITS和trnL-F片段.通过比较,得出以下结论:①标本的制作和储存条件对于植物标本DNA的质量有重要影响;②改进的CTAB法对于桑科榕属植物的DNA提取最为适合;③DNA模版的质量较之其他因素对PCR扩增的影响更大,适当缩短扩增片段的长度对实验的成功是至关重要的.     

半随机单引物PCR扩增产物的特异性研究

以Ｍ１３ｍｐ１９为模板,寡核苷酸“１２２４”为引物,进行半随机单引物ＰＣＲ扩增;分析其扩增产物的限制性内切酶酶切图谱,推定它们分别在Ｍ１３ｍｐ１９序列中的确切位置;证实引物“１２２４”的３端与模板Ｍ１３ｍｐ１９负链的互补结合,至少需有连续的４上个核苷酸,才能产生单引物ＰＣＲ扩增的模板分子,进行有效的ＰＣＲ扩增,并由此决定了扩增产物中各ＤＮＡ片段的大小及其在模板ＤＮＡ序列中的特定位置。     

利用降落PCR扩增KMT-1基因

用试剂盒提取一株牦牛源多杀性巴氏杆菌(C47-8)基因组DNA,同时应用降落PCR和普通PCR扩增KMT-1基因片段。结果表明:降落PCR法扩增出KMT-1基因片段的特异性条带与目的片段长度一致,普通PCR法没有结果。相同的反应体系,降落PCR程序能明显提高PCR的特异性,可用于扩增普通PCR难以扩增的基因片段。     

PCR amplification of Sox genes inMisgurnus anguillicaudatus andParamisgurnus dabryanus (Cypriniforms; Cobitidae)

Using the primers which specially amplify the conservative motif of Human SRY gene, we studied the PCR amplification of Sox genes in genomic DNA of two species of mud loach:Misgurnus anguillicaudatus andParamisgurnus dabryanus. Four bands with the length of 200,550,940 and 1000 bp respectively, were presented in the PCR products ofMisgurnus anguillicaudatus. Three bands with the length of 200,550 and 900 bp were presented in that ofParamisgurnus dabryanus. Southern blotting results indicated that the 200 and 550 bp bands are specially positive. There is no difference between male and female individuals as well as between these two species. Chang zhongjie: Born in Nov. 1965, Ph. D. graduate student     

Insights from the genome of the biotrophic fungal plant pathogen Ustilago maydis

Ustilago maydis is a ubiquitous pathogen of maize and a well-established model organism for the study of plant-microbe interactions. This basidiomycete fungus does not use aggressive virulence strategies to kill its host. U. maydis belongs to the group of biotrophic parasites (the smuts) that depend on living tissue for proliferation and development. Here we report the genome sequence for a member of this economically important group of biotrophic fungi. The 20.5-million-base U. maydis genome assembly contains 6,902 predicted protein-encoding genes and lacks pathogenicity signatures found in the genomes of aggressive pathogenic fungi, for example a battery of cell-wall-degrading enzymes. However, we detected unexpected genomic features responsible for the pathogenicity of this organism. Specifically, we found 12 clusters of genes encoding small secreted proteins with unknown function. A significant fraction of these genes exists in small gene families. Expression analysis showed that most of the genes contained in these clusters are regulated together and induced in infected tissue. Deletion of individual clusters altered the virulence of U. maydis in five cases, ranging from a complete lack of symptoms to hypervirulence. Despite years of research into the mechanism of pathogenicity in U. maydis, no 'true' virulence factors had been previously identified. Thus, the discovery of the secreted protein gene clusters and the functional demonstration of their decisive role in the infection process illuminate previously unknown mechanisms of pathogenicity operating in biotrophic fungi. Genomic analysis is, similarly, likely to open up new avenues for the discovery of virulence determinants in other pathogens.     

论中性服装的历史性空间

为了探求中性服装的发展空间，分析了着装的历史沿革和人们穿着中性服装的社会条件，论述了体育运动的发展和人们审美观念的转变．结果表明，中性化服装的存在不是一种偶然和个别的现象，而是有着生存和发展的无限空间的结论．     

禽源致病性沙门氏菌四环素耐药性基因tetC的PCR扩增及序列分析

通过对临床分离并经生化实验和血清学试验鉴定的20株禽源沙门氏菌和1株标准株C79-13进行药敏试验,结果证明:有19株有高耐药性,另外2株有低耐药性,耐药率达100%;对其四环素耐药基因tetC进行了扩增,结果获得以质粒为模板的特异性产物,与药敏试验符合率为100%;利用PCR检测四环素耐药基因tetC具有很高的敏感性和特异性,从而为禽类致病性沙门氏菌的耐药性检测提供了高效敏感的手段.     

失态的季节:历史回忆中的自我反思--对转型时期知识分子小说的解读

知识分子是如何成为一个"奴在心者"的,这是知识分子小说反思的一个重点。所谓的奴在心者,就是极左路线以"革命"的神圣名义,使本来具有知识分子操守的一代革命青年逐渐背弃自我、放弃独立思想,成为人格萎缩、不敢言说、惟命是从、陷入失语状态的"植物知识分子"。如何从盲信到无信是知识分子小说反思的另一重点。知识分子经历了狂热、盲信、迷信的"恋爱的季节"后,在自己的命运大幅度转弯,精神上遭遇了前所未有的冲击时,他们顿时进入了"失态的季节"。由于自身软弱的限制,他们中的大部分很快的妥协、退让,使人文精神大面积塌陷。他们在肉体和精神的双重磨难中,灵魂走向了麻木、冷漠、虚无。他们的冷漠导致了时代的冷漠和邪恶势力的空前嚣张,从一定程度上说明自身启蒙的重要性和急迫性。     

马铃薯StHb1蛋白的亚细胞定位

为了研究马铃薯StHb1蛋白的亚细胞定位情况,采用RT-PCR技术克隆到马铃薯StHb1基因cDNA序列,并成功构建了StHb1基因与绿色荧光蛋白基因的融合表达载体pBI121-StHb1-GFP.利用农杆菌介导法将重组载体转化洋葱内表皮细胞,通过荧光显微镜观察融合蛋白的瞬时表达以确定StHb1蛋白在细胞内的分布.结果表明StHb1蛋白主要分布于细胞核中.     

小康目标的历史哲学解构

党的十六大提出的小康目标，从历史主体看，是人的全面发展和社会的全面发展的统一：从历史发展看，是阶段性与过程性的统一；从历史动力看，是生产力推动与人民群众创造的统一。中国特色社会主义，正是对马克思“世界历史”思想的全面理解和付诸实行，是对历史规律和主体选择关系的辩证把握。     

论我党历史上的四次历史性转变

在中国共产党90华诞之际,认真研究我党历史上所进行的四次历史性转变及其科学内涵、基本特征、现实意义,对于坚持科学发展,全面建设小康,实现强国之梦,加快推进中国特色社会主义伟大事业,具有十分重要的意义。     

三株微枝形杆菌属菌株的分离鉴定及其抗马铃薯晚疫病菌活性分析

针对分离自内蒙古自治区巴彦淖尔地区的3株形态一致的菌株BM-9、BM-12和BM-15进行鉴定并分析其抗马铃薯晚疫病菌活性。形态鉴定结果表明,三个菌株菌落形态呈透明或半透明状,颜色为乳白色或肉粉色,表面凸起,边缘光滑,出现完整菌膜,在涂有大肠杆菌的培养基上培养6 d左右可观察到棕色颗粒状物质。细胞呈短杆状,(0.425~0.51)μm×(0.425~1.7)μm。16S r DNA序列分析表明,这三个菌株的16S r DNA序列同微枝形杆菌属(microvirga sp.)的序列相似度均达到98%以上。结合形态特征及16S r DNA序列分析结果,菌株BM-9、BM-12和BM-15属于微枝形杆菌属。三个菌株均有明显的溶大肠杆菌活性及不同程度的抗马铃薯晚疫病菌活性。其中菌株BM-9抗马铃薯晚疫病菌活性最强,平板对峙抑制距离为15 mm,菌丝的生长抑制率达到60%。本研究进一步加深了对微枝形杆菌属的了解,为未来微枝形杆菌属针对性的研究提供了一定的参考。     

Mediation of pathogen resistance by exudation of antimicrobials from roots

Most plant species are resistant to most potential pathogens. It is not known why most plant-microbe interactions do not lead to disease, although recent work indicates that this basic disease resistance is multi-factorial. Here we show that the exudation of root-derived antimicrobial metabolites by Arabidopsis thaliana confers tissue-specific resistance to a wide range of bacterial pathogens. However, a Pseudomonas syringae strain that is both at least partly resistant to these compounds and capable of blocking their synthesis/exudation is able to infect the roots and cause disease. We also show that the ability of this P. syringae strain to block antimicrobial exudation is dependent on the type III secretory system.     

从历史角度看“信达雅”——兼驳《是“信”,还是“信达雅”？》

几十年来翻译界对严复提出的＂信达雅＂翻译标准褒贬不一,批判者认为＂信达雅＂理论不足取。常谢枫先生撰文《是＂信＂,还是＂信达雅＂？》批评严复的＂信达雅＂翻译标准自身存在缺陷,且给翻译事业带来危害,而＂信＂才是翻译的唯一标准。事实上,许多批判者都未能将＂信达雅＂作为一个整体进行分析,更未能考量其历史背景,从而导致了理解偏差,误读了严复＂信达雅＂的本意并且忽略了＂信达雅＂的历史意义。     

当代文学的历史意识与未来关怀

如何进入和表现二十世纪中国波诡云谲的历史,这是体现当代文学的历史意识、同时也关联着现实观的基本问题.以当代文学的乡土题材小说为主要对象,反思新时期以来文学表现出的历史意识,认为当代文学存在着一种以古代文化传统和改革开放以来形成的市场经济传统压抑二十世纪革命传统的历史观,在此历史观支配下,文学会丧失基于时代发展的内在动力把握现实的品格.同时探讨了如何在着眼于关怀未来的视野下发挥文学重塑世道人心之功能的问题.