生物素标记寡核苷酸探针检测B群轮状病毒

用５′端接氨基标记法,用生物素对Ｂ群轮状病毒（ＧＢＲＶ）ＩＤＩＲ株具有群特异性的３片段基因上２３ｂｐ寡核苷酸序列进行标记,经高效薄层层析板（ＨＰＴＬＣ）纯化,制备了Ｂ群轮状病毒生物素寡核苷酸探针,探针显色灵敏度达１０Ｐｇ,与ＧＢＲＶ、ＫＢ６３株基因杂交可检测到１００ｐｇ靶序列,而与Ａ群和Ｃ群轮状病毒及无关基因均不产生杂交信号,该探针可用于Ｂ群轮状病毒的检测、鉴定,以及同群不同毒株间基因相关性研究。     

纳米金标记核酸探针检测小反刍兽疫 病毒核酸的研究

试验旨在探讨利用纳米金标记寡核苷酸探针快速检测小反刍兽疫病毒核酸的方法。针对小反刍兽疫病毒N基因的高度保守区设计两条特异寡核苷酸探针,一条探针5’端修饰生物素,另一条探针3’端修饰巯基。巯基化的探针通过Au-S键连接到纳米金颗粒上。靶核酸两端分别与两条探针结合,形成"生物素化探针-靶核酸-纳米金探针"复合物,该复合物通过生物素-亲和素系统,固定在固相载体上,最后银染放大信号。通过肉眼观察法、光镜观察法、分光光度法分析银染灰度,从而间接测定靶核酸的量。初步检测PPRV核酸最低浓度达10fmol/L,所需时间约为1.5h。该方法灵敏度高、操作简单,为临床检测小反刍兽疫病毒核酸提供实验数据和技术支持。     

生物素掺入PCR产物的反向杂交技术分析HLA基因型

本文介绍了与常规生物素或荧光标记引物不同,以及与同位素掺入ＰＣＲ产物不同的反向杂交技术,研究了生物素最佳掺入条件,测出加尾探针联结到尼龙膜上所需紫外光的强度,比较了生物素５＇端标记引物与生物素掺入ＰＣＲ产物的显色灵敏度,并根据实验测得的最佳条件分析了３个标准细胞株ＨＬＡ－ＤＰＢ_１基因型。     

生物素掺入PCR产物的反向杂交技术分析HLA基因型

本文介绍了与常规生物素或荧光标记引物不同,以及与同位素掺入ＰＣＲ产物不同的反向杂交技术,研究了生物素最佳掺入条件,测出加尾探针联结到尼龙膜上所需紫外光的强度,比较了生物素５＇端标记引物与生物素掺入ＰＣＲ产物的显色灵敏度,并根据实验测得的最佳条件分析了３个标准细胞株ＨＬＡ－ＤＰＢ１基因型。     

基因扩增产物的固相杂交-酶联显色方法的建立

建立基于基因扩增技术的简便、快速的病毒核酸定量检测方法．将标记有生物素的寡核苷酸引物所扩增的病毒基因产物,与通过共价键结合在微孔反应板上的特异性探针进行快速杂交,然后通过辣根过氧化物酶标记的抗生物素进行酶联显色,读取光密度值．应用本方法对血清中乙型、丙型肝炎病毒核酸定量检测,灵敏度分别可达１－５拷贝／反应．此方法简便、快速、特异性好、敏感性高、半定量指标客观,可广泛应用于肝炎病毒感染的临床诊断和疗效评价．     

生物素标记寡核苷酸探针探测扩增的病理性突变珠蛋白基因

用末端转移酶催化生物素核苷酸底物(Biotin-ll-dUTP)共价连接在合成的寡核苷酸3’羟基末端,从而合成了两种寡核苷酸探针(β~T_(41-42)及β~A_(41-42))。用它们分别与克隆化扩增的正常和突变的β—珠蛋白基因片段杂变。结果表明该探针都具有与~(32)P探针相似的特异性,其杂交的灵敏度为2—3pg(特异序列)。进而将探测HbS基因的正常和异常两种寡核苷酸19聚体(β~A_6和β~S_6)用~(32)P和生物素分别标记;将HbS杂合子病人的白细胞DNA经聚合酶链反应(PCR)法扩增,并以含正常β—珠蛋白基因的DNA片段作对照,与两种探针分别进行斑点杂交。所得结果完全一致;Hbs杂合子DNA对正常和异常探针都显出杂交信号,而正常DNA只与β~A探针显杂交信号。     

诺如病毒RT-PCR-反向斑点杂交检测方法的建立

旨在建立诺如病毒RT-PCR-反向斑点杂交检测方法。选取诺如病毒较为保守的RdRp基因作为扩增对象,经RT-PCR扩增后将目的片段克隆到pGEM-T载体中。以重组质粒为模版,选择合成寡核苷酸探针及生物素标记引物。生物素标记引物的扩增产物经热变性后与固定在硝酸纤维素膜上的探针进行杂交反应,经显色后判定结果。出现明显的蓝紫色斑点为诺如病毒阳性,如无斑点则为阴性。对5份临床样品进行检测,并以RT-PCR对比验证。结果显示,利用反向斑点杂交法对重组质粒的检测限为100拷贝/μL,在5例实际样品检测中有1例为阳性,与RT-PCR判定结果一致。建立了诺如病毒的RT-PCR-反向斑点杂交检测方法,该方法特异性好,灵敏度高,操作简便,具有重要的应用价值。     

生物素标记DX_(13)探针及一例甲型血友病家系分析

 以Bio-ll-dUTP替代dTTP经二步法缺口平移标记DNA片段制得生物素DX_(13)探针。其碱性磷酸酶ABC体系显色灵敏度为100fg(约5×10~(-18)mol);与5μg染色体DNA进行Southern印迹杂交,可得清晰的单拷贝杂交区带。以此探针对一血友病家系做RFLP分析,确定两成员为甲型血友病基因携带者。与32P探针对比,两种探针的杂交和分析结果完全一致。表明高标记的生物素探针可应用于单拷贝基因分析和基因诊断。     

银染增强的纳米金标记探针对微量核酸的检测

本研究利用银染增强的纳米金技术建立了一种简单快速的核酸定量方法.该方法基于纳米金与烷巯基修饰的寡核苷酸分子共价键合作用,将纳米微粒报告基团标记在与靶核酸一端序列互补的寡核苷酸上,同时生物素化修饰另一端互补序列.靶核酸与两段寡核苷酸探针杂交后,借亲和素固定在酶标板孔内,通过纳米金催化的银染放大效应产生高灵敏的识别信号,适时记录其吸光度值从而实现核酸分子的定量.该检测方法检测单链核酸分子的灵敏度达0.1 fM,双链分子为10 fM.     

一种简易SNP检测方法的建立

目的：建立一种快速、简单的SNP（Single Nucleotide Polymorphisms）检测方法。方法：设计带生物素标记的扩增引物对检测用具有单碱基差异的野生型和突变型靶序列分别进行扩增,然后通过紫外交联的方式将相应检测靶序列的探针固定在硝酸纤维素膜上,借助Taq酶完成膜上单引物延伸,从而对探针捕获的靶序列进行延伸固定在膜上,最后使用生物素．亲和素酶联显色（ABs-ELISA）反应肉眼观察结果。结果：阳性和阴性对照探针显示正常。野生型探针和突变型探针能够分别特异性结合靶序列,并通过生物素和亲和索显色系统放大为一种肉眼可判断结果的检测形式。结论：建立了一种基于硝酸纤维素膜载体上进行核酸扩增的SNP检测方法。     

Fluorescence Characteristics of Hydrophobic Partial Agonist Probes of the Cholecystokinin Receptor

Fluorescence spectroscopic studies are powerful tools for the evaluation of receptor structure and the dynamic changes associated with receptor activation. Here, we have developed two chemically distinct fluorescent probes of the cholecystokinin (CCK) receptor by attaching acrylodan or a nitrobenzoxadiazole moiety to the amino terminus of a partial agonist CCK analogue. These two probes were able to bind to the CCK receptor specifically and with high affinity, and were able to elicit only submaximal intracellular calcium responses typical of partial agonists. The fluorescence characteristics of these probes were compared with those previously reported for structurally-related full agonist and antagonist probes. Like the previous probes, the partial agonist probes exhibited longer fluorescence lifetimes and increased anisotropy when bound to the receptor than when free in solution. The receptor-bound probes were not easily quenched by potassium iodide, suggesting that the fluorophores were protected from the extracellular aqueous milieu. The fluorescence characteristics of the partial agonist probes were quite similar to those of the analogous full agonist probes and quite distinct from the analogous antagonist probes. These data suggest that the partially activated conformational state of this receptor is more closely related to its fully active state than to its inactive state.     

Extensive set of 16S rRNA-based probes for detection of bacteria in human feces

For the detection of six groups of anaerobic bacteria in human feces, we designed seven new 16S rRNA-based oligonucleotide probes. This set of probes extends the current set of probes and gives more data on the composition of the human gut flora. Probes were designed for Phascolarctobacterium and relatives (Phasco741), Veillonella (Veil223), Eubacterium hallii and relatives (Ehal1469), Lachnospira and relatives (Lach571), and Eubacterium cylindroides and relatives (Ecyl387), and two probes were designed for Ruminococcus and relatives (Rbro730 and Rfla729). The hybridization conditions for the new probes were optimized for fluorescent in situ hybridization, and the probes were validated against a set of reference organisms. The probes were applied to fecal samples of 11 volunteers to enumerate their target bacterial groups. The Phasco741 and Veil223 probes both detected average numbers below 1% of the total number of bacteria as determined with the bacterial kingdom-specific Bact338 probe. The Ecyl387 probe detected about 1.4%, the Lach571 and Ehal1469 probes detected 3.8 and 3.6%, respectively, and a combination of the Rbro730 and Rfla729 probes detected 10.3%. A set of 15 probes consisting of probes previously described and those presented here were evaluated in hybridization with the fecal samples of the same volunteers. Together, the group-specific probes detected 90% of the total bacterial cells.     

Extensive Set of 16S rRNA-Based Probes for Detection of Bacteria in Human Feces

For the detection of six groups of anaerobic bacteria in human feces, we designed seven new 16S rRNA-based oligonucleotide probes. This set of probes extends the current set of probes and gives more data on the composition of the human gut flora. Probes were designed for Phascolarctobacterium and relatives (Phasco741), Veillonella (Veil223), Eubacterium hallii and relatives (Ehal1469), Lachnospira and relatives (Lach571), and Eubacterium cylindroides and relatives (Ecyl387), and two probes were designed for Ruminococcus and relatives (Rbro730 and Rfla729). The hybridization conditions for the new probes were optimized for fluorescent in situ hybridization, and the probes were validated against a set of reference organisms. The probes were applied to fecal samples of 11 volunteers to enumerate their target bacterial groups. The Phasco741 and Veil223 probes both detected average numbers below 1% of the total number of bacteria as determined with the bacterial kingdom-specific Bact338 probe. The Ecyl387 probe detected about 1.4%, the Lach571 and Ehal1469 probes detected 3.8 and 3.6%, respectively, and a combination of the Rbro730 and Rfla729 probes detected 10.3%. A set of 15 probes consisting of probes previously described and those presented here were evaluated in hybridization with the fecal samples of the same volunteers. Together, the group-specific probes detected 90% of the total bacterial cells.     

Detection of calcitonin-encoding mRNA by radioactive and non-radioactive in situ hybridization: improved colorimetric detection and cellular localization of mRNA in thyroid sections

The localization of mRNA encoding calcitonin was studied by in situ hybridization using 35S-labeled RNA probes and biotin-labeled DNA probes. Radiolabeled probes were detected by autoradiography and biotin-labeled probes by streptavidin-biotin-peroxidase. To intensify the colorimetric signal, the indirect avidin-biotin complex (ABC) method was performed. However, the results were often variable. To improve the sensitivity, the peroxidase reaction signal was enhanced with a gold-silver deposit intensification reaction. To shorten the incubation times and to enhance the colorimetric reaction, several reaction steps were performed in a microwave oven. The localization of calcitonin mRNA in thyroid tissue, as detected with in situ hybridization, was confirmed by immunohistochemical localization of the calcitonin polypeptide. The results of in situ hybridization using biotinylated probes were compared to in situ hybridization using radioactive probes. Our data show that the results of in situ hybridization applied on frozen and paraffin-embedded sections using biotinylated DNA probes, detected with an indirect streptavidin-biotin-peroxidase reaction and intensified by silver-gold enhancement, were comparable to those obtained with radioactive probes. The localization of calcitonin encoding mRNA was in agreement with the localization of the calcitonin polypeptide.     

Non-isotopic RNA probes. Comparison between different labels and detection systems

Several studies have shown the use of non-radioactive labelled DNA probes for in situ hybridisation, mainly to identify cellular DNA. In this study mRNA in situ hybridisation was performed on rat pituitary with biotinylated complementary (c) RNA probes for rat prolactin and growth hormone (GH), and compared with radioactive 35S-radiolabelled probes. Biotinylated cRNA probes were labelled with either biotin-11-UTP or with allylamine-UTP, the latter method being able to produce a higher yield of labelled RNA. Different detection systems were tested, and hybridisation signal was seen in cells of anterior pituitary with both types of biotinylated probes. The signals were detected using either avidin-biotin-complex with peroxidase (ABC), peroxidase-anti-peroxidase (PAP) or gold-silver methods. ABC peroxidase detected using glucose oxidase-diaminobenzidine (DAB)-nickel solution appeared to be the best method for detecting labelled RNA probes, with very strong signal and low background. The biotinylated probes were comparable in sensitivity to the radiolabelled probes in detecting prolactin and GH mRNAs in the anterior lobe of the rat pituitary. These results indicate an alternative methods of labelling and detection of biotinylated probes which could have a potential role in research and diagnostic techniques.     

Non-isotopic RNA probes

Summary Several studies have shown the use of non-radioactive labelled DNA probes for in situ hybridisation, mainly to identify cellular DNA. In this study mRNA in situ hybridisation was performed on rat pituitary with biotinylated complementary (c) RNA probes for rat prolactin and growth hormone (GH), and compared with radioactive ³⁵S-radiolabelled probes. Biotinylated cRNA probes were labelled with either biotin-11-UTP or with allylamine-UTP, the latter method being able to produce a higher yield of labelled RNA. Different detection systems were tested, and hybridisation signal was seen in cells of anterior pituitary with both types of biotinylated probes. The signals were detected using either avidin-biotin-complex with peroxidase (ABC), peroxidase-anti-peroxidase (PAP) or gold-silver methods. ABC peroxidase detected using glucose oxidase-diaminobenzidine (DAB)-nickel solution appeared to be the best method for detecting labelled RNA probes, with very strong signal and low background. The biotinylated probes were comparable in sensitivity to the radiolabelled probes in detecting prolactin and GH mRNAs in the anterior lobe of the rat pituitary. These results indicate an alternative methods of labelling and detection of biotinylated probes which could have a potential role in research and diagnostic techniques.     

Use of oligodeoxynucleotide signature probes for identification of physiological groups of methylotrophic bacteria

Oligodeoxynucleotide sequences that uniquely complemented 16S rRNAs of each group of methylotrophs were synthesized and used as hybridization probes for the identification of methylotrophic bacteria possessing the serine and ribulose monophosphate (RuMP) pathways for formaldehyde fixation. The specificity of the probes was determined by hybridizing radiolabeled probes with slot-blotted RNAs of methylotrophs and other eubacteria followed by autoradiography. The washing temperature was determined experimentally to be 50 and 52 degrees C for 9-alpha (serine pathway) and 10-gamma (RuMP pathway) probes, respectively. RNAs isolated from serine pathway methylotrophs bound to probe 9-alpha, and RNAs from RuMP pathway methylotrophs bound to probe 10-gamma. Nonmethylotrophic eubacterial RNAs did not bind to either probe. The probes were also labeled with fluorescent dyes. Cells fixed to microscope slides were hybridized with these probes, washed, and examined in a fluorescence microscope equipped with appropriate filter sets. Cells of methylotrophic bacteria possessing the serine or RuMP pathway specifically bind probes designed for each group. Samples with a mixture of cells of type I and II methanotrophs were detected and differentiated with single probes or mixed probes labeled with different fluorescent dyes, which enabled the detection of both types of cells in the same microscopic field.     

Use of oligodeoxynucleotide signature probes for identification of physiological groups of methylotrophic bacteria.

Oligodeoxynucleotide sequences that uniquely complemented 16S rRNAs of each group of methylotrophs were synthesized and used as hybridization probes for the identification of methylotrophic bacteria possessing the serine and ribulose monophosphate (RuMP) pathways for formaldehyde fixation. The specificity of the probes was determined by hybridizing radiolabeled probes with slot-blotted RNAs of methylotrophs and other eubacteria followed by autoradiography. The washing temperature was determined experimentally to be 50 and 52 degrees C for 9-alpha (serine pathway) and 10-gamma (RuMP pathway) probes, respectively. RNAs isolated from serine pathway methylotrophs bound to probe 9-alpha, and RNAs from RuMP pathway methylotrophs bound to probe 10-gamma. Nonmethylotrophic eubacterial RNAs did not bind to either probe. The probes were also labeled with fluorescent dyes. Cells fixed to microscope slides were hybridized with these probes, washed, and examined in a fluorescence microscope equipped with appropriate filter sets. Cells of methylotrophic bacteria possessing the serine or RuMP pathway specifically bind probes designed for each group. Samples with a mixture of cells of type I and II methanotrophs were detected and differentiated with single probes or mixed probes labeled with different fluorescent dyes, which enabled the detection of both types of cells in the same microscopic field.     

The development and assessment of DNA and oligonucleotide probes for the specific detection of Bacillus anthracis

Two DNA probes and a number of oligonucleotide probes were designed from the virulence factor genes of Bacillus anthracis. These probes were tested for specificity against 52 B. anthracis strains and 233 Bacillus strains encompassing 23 other species. A rapid slot blotting technique was used for screening the large numbers of isolates involved. All probes tested appeared to be specific for B. anthracis under high stringency conditions. These probes could differentiate between virulent and avirulent strains. The probes were also applied to the detection of B. anthracis in routine environmental and clinical samples. A non-radioactive hybridization and detection system based on digoxigenin-11-dUTP was developed.     

A novel means to develop strain-specific DNA probes for detecting bacteria in the environment.

A simple means to develop strain-specific DNA probes for use in monitoring the movement and survival of bacteria in natural and laboratory ecosystems was developed. The method employed amplification of genomic DNA via repetitive sequence-based PCR (rep-PCR) using primers specific for repetitive extragenic palindromic (REP) elements, followed by cloning of the amplified fragments. The cloned fragments were screened to identify those which were strain specific, and these were used as probes for total genomic DNA isolated from microbial communities and subjected to rep-PCR. To evaluate the utility of the approach, we developed probes specific for Burkholderia cepacia G4 and used them to determine the persistence of the strain in aquifer sediment microcosms following bioaugmentation. Two of four probes tested were found to specifically hybridize to DNA fragments of the expected sizes in the rep-PCR fingerprint of B. cepacia G4 but not to 64 genetically distinct bacteria previously isolated from the aquifer. One of these probes, a 650-bp fragment, produced a hybridization signal when as few as 10 CFU of B. cepacia G4 were present in a mixture with 10(6) CFU nontarget strains, indicating that the sensitivity of these probes was comparable to those of other PCR-based detection methods. The probes were used to discriminate groundwater and microcosm samples that contained B. cepacia G4 from those which did not. False-positive results were obtained with a few samples, but these were readily identified by using hybridization to the second probe as a confirmation step. The general applicability of the method was demonstrated by constructing probes specific to three other environmental isolates.