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应用South—Western blot mapping方法观察了初步提纯的锥虫转录变异抗原基因的聚合酶与其基因组DNA片段的结合情况.在选定的试验条件下,初步纯化的RNA聚合酶既能与变异抗原基因结合,也能与一些待鉴定的非特异性核酸片段结合.本文对存在的问题进行了讨论. 相似文献
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自从DNA重组技术问世以来，人类建立了许多表达系统来生产有活性的蛋白特别是昂贵的药用蛋白。尽管利用DNA重组技术在微生物中表达外源蛋白技术已经成熟，但是该系统不能进行真核蛋白的加工，如糖基化以及某些蛋白谷氨酰胺的二羧基化等，而这对于蛋白的生物学活性极为重要。另一方面，从大肠杆菌、酵母到哺乳动物细胞的基因工程表达系统，成本高，分离纯化复杂，对生产建设投资要求 相似文献
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锥—46抑制[^3H]次黄嘌呤掺入伊氏锥虫核酸的研究 总被引：2，自引：1，他引：1
用液体闪烁计数法对锥—46的抗锥虫作用的机理做了初步研究。发现T-46与Berenil很相似,均可显著抑制[~3H]次黄嘌呤掺入伊氏锥虫,抑制作用与浓度及时间呈正相关。T-46和Berenil对DNA合成的IC_(60)分别为1.33和1.73μg·ml~(-1)。本实验还提示T-46抗锥虫作用可能与损伤DNA模板有关。 相似文献
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利用盐溶法分离制备动物基因组DNA和RNA的方法,并对实验过程进行改良和分析。实验中选用新鲜猪肝作为实验材料,根据核糖核蛋白与脱氧核糖核蛋白在一定浓度的氯化钠溶液中的溶解度不同进行分离,利用SDS裂解,氯仿、异戊醇抽提,分离得到猪肝脏中基因组DNA和RNA;同时,通过脱氧核糖和核糖的显色反应定性区分了DNA和RNA;实验最后利用紫外分光光度法和二苯胺法定量测定了DNA样品中的DNA的含量。 相似文献
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《中国兽医学报》2016,(6):1008-1014
核酸适配体作为一种优于单克隆抗体的新型识别分子,具有更高的分辨率,能识别配体间一个基团的细微差别,且所需的结合活性位点更小。本研究利用指数级富集配体进化技术(SELEX)筛选特异性结合于奶牛结合珠蛋白(HP)的DNA适配体,并对筛取的适配体进行特性分析。体外构建全长80bp中间含40bp随机序列的单链DNA(ssDNA)文库,通过对循环次数、退火温度及引物比例的优化,建立了适合的筛选体系;以超滤离心管为介质,HP蛋白为靶标,对随机ssDNA文库进行反复的SELEX筛选,从单链DNA文库中筛选能特异性结合HP蛋白的核酸适配体;利用DNAMAN和RNAstructure软件对获得核酸适配体进行一级结构和二级结构分析。结果表明,经过体外8轮筛选,随机ssDNA文库与HP蛋白的结合率由1.86%上升到31.35%,特异性核酸达到最大富集;经克隆和测序,获得了能与HP蛋白特异性结合的5个家族的DNA适配体,同源性均达70%以上,RNAstructure分析其二级结构主要以茎环结构为主,表明ssDNA形成不同的茎环结构可能是适配体与HP蛋白特异性作用的结构基础。初步建立HP蛋白核酸适配体库,筛选到与HP蛋白特异性结合的核酸适配体,为制备以HP为检测靶标的奶牛隐性乳腺炎检测试剂盒奠定基础。 相似文献
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克隆羊外膜蛋白Omp25基因,在大肠杆菌中表达、纯化,并对Omp25蛋白的抗原性进行分析.以布鲁氏菌染色体DNA模板,扩增Omp25基因,双酶切后克隆至pET32a上,在大肠杆菌ER2566 (DE3)中诱导表达,组氨酸结合树脂柱纯化,Western blotting鉴定Omp25蛋白的免疫原性.将Omp25克隆至载体pET32a,提取的重组质粒经PCR鉴定、双酶切鉴定和测序分析确定目的基因成功插入到了克隆载体中.将重组质粒转化于大肠杆菌ER2566 (DE3)中表达获得HIS融合蛋白,SDS-PAGE分析证明,表达产物为43 000的融合蛋白.Western blotting分析表明,所表达的蛋白具有免疫原性.结果表明,成功地表达并纯化了Omp25蛋白,而且纯化的蛋白具有一定的免疫原性.本试验为进一步研究Omp25蛋白的功能以及寻找布鲁氏菌的诊断性蛋白奠定了基础. 相似文献
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本文介绍一种检测伊氏锥虫循环抗原的双抗体夹心酶联免疫吸附试验。这种试验敏感性和特异性高,检查实验室制备的伊氏锥虫可溶性抗原,可检出的阈值为0.049—0.195微克蛋白/毫升(0.122±0.066微克蛋白/毫升);检查泰氏锥虫和龚地弓形体抗原,即使抗原浓度分别高达180微克蛋白/毫升和200微克蛋白/毫升,亦为阴性。用此法观察了7只实验感染家兔血清中伊氏锥虫循环抗原的动态,实验兔于感染后4—8天首次呈现抗原血症,滴度于感染后8—10天达高峰,持续仅4—12天,于感染后14—28天转为阴性,而实验感染前和用拜耳205治疗后的血清则全部阴性。将治疗前已转阴的15份血清和治疗后的28份血清标本按Bout等介绍的方法解离免疫复合物再检循环抗原,前者10份阳性,后者全部阴性.此结果证明,实验感染兔于感染后2—4周血清中出现伊氏锥虫抗原-抗体免疫复合物,复合物的产生影响循环抗原的检出。 相似文献
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为构建猪链球菌(Streptococcus suis)蛋白表面展示系统,本研究通过序列分析,确定猪链球菌的LPxTG蛋白及其信号肽(SP)和胞壁锚定基序(CWA),通过PCR扩增Peno-SP、GFP、CWA的DNA片段并融合,构建强启动子Peno控制表达编码SP-GFP-CWA融合蛋白的DNA片段,将该重组DNA片段连接pSET2载体,获得蛋白表面展示质粒,转化猪链球菌,构建得到以GFP为报告蛋白的猪链球菌蛋白表面展示系统。结果显示,利用猪链球菌的10个LPxTG蛋白及其SP和CWA序列,构建了10个含有Peno-SP-GFP-CWA融合片段的重组pSET2表面蛋白展示质粒pSsPSD1至pSsPSD10,分别转化猪链球菌05ZYH33,PCR鉴定显示其中7个转化猪链球菌。采用western blot初步检测其展示蛋白,结果显示,7个转化阳性菌株均能有效表达GFP蛋白,以成熟GFP条带为指标,均表现出了一定的外源GFP表面展示水平,分别命名为SsPSD1、SsPSD2、SsPSD4、SsPSD7-SsPSD10,其中SsPSD1、SsPSD4、SsPSD8和SsPSD9表面展示水平相对较好,在猪链球菌表面展示外源蛋白方面具有很好的潜力。本研究首次尝试建立猪链球菌蛋白表面展示系统,为猪链球菌表面递呈外源蛋白或抗原提供了新的策略。 相似文献
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A method for rapid differentiation between the EHV 1 live vaccine strain Rac H and field isolates is described. Total DNA was isolated from virus-infected small scale cell cultures. DNA fragments digested with restriction endonuclease BamHI were separated, transferred and immobilized on filter membranes. A Digoxigenin-labeled probe derived from EHV 1 was used for hybridization. This probe hybridized specifically to sequences of the inverted terminal repeat region which in case of Rac H include a deletion of 0.8 kb. By comparing the different migration patterns after blot hybridization it could be shown that in 65 isolates from cases of abortion the live vaccine strain Rac H was not involved. 相似文献
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高致病猪繁殖与呼吸综合征病毒JXA1株Nsp2基因分段克隆表达及其单克隆抗体的制备 总被引：1，自引：1，他引：0
分析猪繁殖与呼吸综合征病毒（porcine reproductive and respiratory syndrome virus, PRRSV）非结构蛋白Nsp2,扩增和克隆JXA1株Nsp2基因的4个片段,并将它们分别插入pGEX-6P-1表达载体构建重组表达质粒,经IPTG 诱导表达得到蛋白,纯化后进行活性鉴定。以分段表达的蛋白为抗原,建立间接ELISA方法用于杂交瘤细胞株的筛选。用PRRSV NVDC-JXA1株灭活疫苗对BALB/c小鼠进行常规免疫,最后一次用活毒加强免疫,取其脾细胞与SP2/0细胞在聚乙二醇作用下融合,经过选择性培养、有限稀释筛选到1株针对Nsp2的杂交瘤细胞株6B8。鉴定结果表明,该株杂交瘤细胞仅与4个蛋白片段中的Nsp2F1有反应,细胞经长期体外培养和冻存后复苏能稳定分泌抗体,上清效价达1∶210,腹水效价达1∶106。本研究成功表达了4个PRRSV JXA1株的非结构蛋白Nsp2的片段,以其为抗原建立筛选方法,得到1株针对Nsp2的单克隆抗体,为研究Nsp2功能和建立相关诊断方法奠定物质基础。 相似文献
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The recombinant DNA technology or DNA cloning permits the isolation, amplification, and precise manipulation of specific DNA fragments. This is generally accomplished by linking or recombining the desired DNA fragment with a DNA molecule, termed the vector, which is capable of directing the replication of itself in a suitable host cell and any DNA segment covalently attached to it. Using this and associated technologies, it is possible to produce large amounts of specific proteins and to modify cell types by introducing the genes for proteins that are otherwise absent. Moreover, it is now possible to construct variants of naturally-occurring proteins with improved biological or physical properties. 相似文献
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Identification and partial characterization of the hemolysin (HlyII) of Actinobacillus pleuropneumoniae serotype 2 总被引：4，自引：0，他引：4
The secreted hemolytic activity produced by Actinobacillus pleuropneumoniae serotype 2 reference strain is thermolabile, inactivated by proteinase K and requires Ca2+ as cofactor for its hemolytic activity. Purification of the hemolytic activity resulted in a fraction containing two proteins, one of 105 kDa and one of 125 kDa. These two proteins could be further separated by preparative SDS polyacrylamide gel electrophoresis. This purification step, resulted in loss of the hemolytic activity. Polyclonal antibodies were made against each of these proteins in rabbits. Neutralization experiments showed that antibodies made against the 105 kDa protein could neutralize the hemolytic activity produced by A. pleuropneumoniae serotype 2, while antibodies made against the 125 kDa protein were unable to neutralize the hemolytic activity. The 105 kDa protein therefore, is the hemolysin of A. pleuropneumoniae serotype 2, known as HlyII. This protein is closely related immunologically to the hemolysin I (HlyI) from A. pleuropneumoniae serotype 1. DNA::DNA hybridization experiments performed by the Southern blot method using the cloned structural gene of HlyI from A. pleuropneumoniae serotype 1 demonstrate that the structural genes of the two hemolysins (hlyIA and hlyIIA) are different and show at least 30% heterology. This confirms that HlyI and HlyII are two different proteins, although they have a very similar molecular weight and show strong immunological cross reactions. 相似文献
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从临床病鸭中分离并鉴定了1型鸭疫里默氏杆菌,并在提取鸭疫里默氏杆菌的基因组DNA后,用Sau3A I酶切,回收大小为0．07～4 kb的片段;将酶切片段与酶切的质粒载体pRSET连接后,电转化大肠杆菌Rosetta,成功构建了1型鸭疫里默氏杆菌的基因组文库,经检测库容量约为40000个。随机筛选30个单菌落,用pRSET通用引物进行PCR鉴定,统计结果显示插入片段的大小93．3％在1～3 kb范围内,成功构建了鸭疫里默氏杆菌基因组文库,为鸭疫里默氏杆菌功能基因的克隆及鉴定奠定了基础。 相似文献
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牛传染性鼻气管炎病毒gE基因的截短克隆与表达 总被引：6，自引：0，他引：6
以牛传染性鼻气管炎病毒Baaha Nu/67株的DNA作为模板，用PCR扩增gE基N并克隆至pGEM-T Easy裁体，再以此质粒作为模板将gE基因分成6个片段，分别插入原核表达载体pET32a并在大肠杆菌中进行了表达。蛋白电泳结果表明6个片段中有2个片段以可溶形式表达，1个片段以包涵体形式表达，另外3个片段没有表达。采用固定化金属离子亲和层析法在非变性条件下对两个可溶性片段进行了纯化。经免疫印迹试验，间接ELISA和交叉试验证明，两个纯化的重组蛋白均与牛传染性鼻气管炎阳性血清样品发生反应，而与牛传染性鼻气管炎阴性血清无任何反应，显示其具有良好的抗原性和特异性，可用于牛传染性鼻气管炎gE-ELISA诊断方法的建立。 相似文献
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Jennings JC Kolwyck DC Kays SB Whetsell AJ Surber JB Cromwell GL Lirette RP Glenn KC 《Journal of animal science》2003,81(6):1447-1455
Questions regarding the digestive fate of DNA and protein from transgenic feed have been raised in regard to human consumption and commercial trade of animal products (e.g., meat, milk, and eggs) from farm animals fed transgenic crops. Using highly sensitive, well-characterized analytical methods, pork loin samples were analyzed for the presence of fragments of transgenic and endogenous plant DNA and transgenic protein from animals fed meal prepared from conventional or glyphosate-tolerant Roundup Ready (RR) soybeans. Pigs were fed diets containing 24, 19, and 14% RR or conventional soybean meal during grower, early-finisher, and late-finisher phases of growth, respectively, and longissimus muscle samples were collected (12 per treatment) after slaughter. Total DNA was extracted from the samples and analyzed by PCR, followed by Southern blot hybridization for the presence of a 272-bp fragment of the cp4 epsps coding region (encoding the synthetic enzyme 5-enolpyruvylshikimate-3-phosphate synthase derived from Agrobacterium sp. strain CP4) and a 198-bp fragment of the endogenous soybean gene le1 (encoding soy lectin). Using 1 microgram of input DNA per reaction, none of the extracted samples was positive for cp4 epsps or le1 at the limit of detection (LOD) for these PCR/Southern blot assays. The LOD for these assays was shown to be approximately one diploid genome equivalent of RR soybean DNA, even in the presence of 10 micrograms of pork genomic DNA. A 185-bp fragment of the porcine preprolactin (prl) gene, used as a positive control, was amplified from all samples showing that the DNA preparations were amenable to PCR amplification. Using a competitive immunoassay with an LOD of approximately 94 ng of CP4 EPSPS protein/g of pork muscle, neither the CP4 EPSPS protein nor the immunoreactive peptide fragments were detected in loin muscle homogenates from pigs fed RR soybean meal. Taken together, these results show that neither small fragments of transgenic DNA nor immunoreactive fragments of transgenic protein are detectable in loin muscle samples from pigs fed a diet containing RR soybean meal. 相似文献
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按常规方法培养大肾传代细胞(MDCK),待细胞长成单层后,以2%的量接种犬Ⅱ型腺病毒弱毒株(MV-CAV_2).当绝大多数细胞出现病变时(约35～40h),直接从感染细胞培养物中提取CAV_2 DNA.以该法提取CAV_2 DNA,不仅操作简便、耗费少,而且产量也比常规的先纯化病毒再提取DNA的方法高2～3倍.该法可普遍用于从感染细胞中提取与蛋白共价结合的所有病毒核酸.采用电泳洗脱法纯化上述CAV_2 DNA,以Eco RI、Bam HI、Pst I、Sac I、Nsi I和Sph I酶切,电泳分离,建立了该病毒DNA的6种限制性内切酶图谱.本实验结果为该病毒DNA的分子克隆奠定了基础. 相似文献
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Species and strain specific identification of lactic acid bacteria in complex microflora 总被引：2，自引：0，他引：2
The identification of lactic acid bacteria in a complex microbiota using bacteriological culture in combination with phenotypic and genotypic identification techniques is laborious and time-consuming. New molecular methods permit a fast and culture-independent characterisation of such microbiota. Denaturing gradient gel electrophoresis (DGGE) of PCR fragments of the 16S rRNA gene has been proven to be a suitable tool. Here the use of PCR-DGGE with group specific primers is described to investigate the dynamic of sourdough microbiota from addition of the starter until the microbiota remained stable. Species were identified by applying an identification ladder obtained from reference strains or by sequence analysis of the PCR fragments. Furthermore, a method for detection of strains in complex microbiota is described. A strain specific chromosomal DNA fragment of Lactobacillus paracasei LTH 2579 was isolated applying the subtraction hybridisation. Based on the acquired target sequence a specific PCR system was established and combined with a PCR system specific for the species L. paracasei. Use of this detection system permitted to identify and quantitatively detect L. paracasei LTH 2579 in fermented sausages and upon consumption in faecal samples. 相似文献