Detection of harmful cyanobacteria and their toxins by both PCR amplification and LC-MS during a bloom event.

We briefly report here the occurrence of toxic blooms in the eutrophic reservoir Billings, S?o Paulo city, Brazil. Water samples were collected in May 2004, during a cyanobacterial bloom. The presence of toxic species was confirmed by using PCR amplifications of a fragment region of genes encoding microcystin synthetase-mcyB. The determination of toxins was performed by liquid chromatography coupled with mass spectrometry (LC-MS). LC-MS analyses of the toxins from the bloom revealed variants of microcystins (MC), such as MC-LR, MC-RR and MC-YR. HPLC-FLD was used to determine the paralytic shellfish poisoning (PSP) saxitoxin (STX), neosaxitoxin (NEO), gonyautoxins 2 (GTX2) and 3 (GTX3). GTX2, GTX3 and NEO were detected for the first time in a natural sample from Billings reservoir. These results are a contribution to the knowledge of the biogeography of toxic cyanobacteria and their toxins, specifically in S?o Paulo.     

Multiplex PCR assay for Cylindrospermopsis raciborskii and cylindrospermopsin-producing cyanobacteria

Water bodies are routinely monitored for the presence of potentially toxic cyanobacteria; however, the methodology for confirming toxicity is currently complex and expensive. Here we describe the application of gene-based technology to rapidly identify cylindrospermopsin-producing cyanobacteria, specifically, Cylindrospermopsis raciborskii. A multiplex polymerase chain reaction (PCR) test was developed that simultaneously identified polyketide synthase (pks) and peptide synthetase (ps) determinants associated with cylindrospermopsin production and distinguished C. raciborskii from other cylindrospermopsin-producing cyanobacteria of the species Anabaena bergii and Aphanizomenon ovalisporum, by targeting the rpoC1 gene. Twenty-one C. raciborskii, 5 A. bergii, 10 Aph. ovalisporum isolates and 3 environmental samples all yielded PCR results consistent with their toxicological status, as assessed by high-performance liquid chromatography coupled to mass spectrometry or matrix-assisted laser desorption ionization-time-of-flight mass spectrometry, and C. raciborskii was always correctly identified. The PCR test is a rapid, reliable, and economical way of assessing the toxic potential of cyanobacterial blooms formed by these organisms.     

Development of a quantitative PCR assay for residual mouse DNA and comparison of four sample purification methods for DNA isolation

Reliable and sensitive assays are required to determine whether a pharmaceutical product meets current regulatory guidelines for residual host cell DNA. In this study, the sensitivity of the qPCR assay was significantly improved by targeting the repetitive elements of mouse genome. This improved method allowed for sensitive and accurate quantitation of mouse genomic DNA in the range of 1 to 10⁶ pg/mL. In addition, four sample purification methods for DNA isolation (Wako DNA extractor kit, MasterPure™ DNA purification kit, PrepSEQ™ residual DNA sample preparation kit, and phenol–chloroform extraction method with addition of glycogen), each representing a different strategy for DNA isolation from proteinaceous solutions, were evaluated by isolating DNA from a mouse monoclonal IgG antibody. Among these methods, Wako DNA extractor kit and MasterPure™ DNA purification kit demonstrated superior DNA recovery, repeatability, and sensitivity, with quantitation limits of 1 pg/mL. To further evaluate these two DNA isolation methods, six replicates of an unspiked mouse polyclonal IgG antibody sample were tested by both methods, and both methods demonstrated a good degree of precision. Therefore, the residual mouse DNA quantitation methods described here represented rapid, accurate, precise, and sensitive procedures that can be used in quality control testing for regulatory compliance in the pharmaceutical industry.     

实时荧光定量PCR法检测食管癌组织中细胞周期蛋白CyclinD1和CyclinA基因的表达

目的检测食管癌组织中细胞周期蛋白CyclinD1和CyclinAmRNA的表达水平,探讨相关基因表达与食管癌发生、发展的相关性。方法应用SYBRGreen染料法进行相对实时荧光定量PCR检测CyclinD1和CyclinA在48例食管癌组织及其癌旁正常食管组织中的表达情况。结果CyclinD1和CyclinA在食管癌组织中的表达水平均明显高于正常食管黏膜组织,差异具有统计学意义（P〈0．05）。结论人食管癌组织中CyclinD1和CyclinA的高表达可能与食管癌的发生发展密切相关,有望作为食管癌发生发展的评估指标。     

Multiplex PCR for detection of microcystins‐producing cyanobacteria from freshwater samples

The aim of this study was to develop a PCR‐based method of gene‐directed multiplex PCR to rapidly identify microcystins producing cyanobacteria, regardless of their taxa, that could be applied in routine freshwater monitoring. Instead of using the amplification of only one or two mcy gene fragments, a multiplex PCR that simultaneously amplifies mcyA‐cd, mcyAB, and mcyB fragments of the microcystin gene cluster was validated with DNA from 124 cyanobacterial isolates and applied in 37 environmental samples. The toxicological status of the isolates was assessed by high‐performance liquid chromatography also used as the “gold standard” for the evaluation of multiplex mcy genes‐based PCR, where a sensitivity of 92.3% and a specificity of 100% have been obtained. For the environmental samples, a rapid protocol for their direct use in the PCR reaction has been developed and, by using ELISA results as “gold standard” for the presence of microcystins in these samples, a sensitivity of 80% and a specificity of 100% were achieved, showing that this multiplex PCR test is a rapid, reliable, and economical way of assessing the microcystin‐producing potential of cyanobacteria in freshwaters, regardless of their taxa or microcystins variant produced. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2010.     

The role of organic anion transporting polypeptides (OATPs/SLCOs) in the toxicity of different microcystin congeners in vitro: A comparison of primary human hepatocytes and OATP-transfected HEK293 cells

Cellular uptake of microcystins (MCs), a family of cyclic cyanobacterial heptapeptide toxins, occurs via specific organic anion transporting polypeptides (OATPs), where MCs inhibit serine/threonine-specific protein phosphatase (PP). Despite comparable PP-inhibitory capacity, MCs differ greatly in their acute toxicity, thus raising the question whether this discrepancy results from MC-specific toxikokinetic rather than toxicodynamic differences. OATP-mediated uptake of MC congeners MCLR, -RR, -LW and -LF was compared in primary human hepatocytes and HEK293 cells stably expressing recombinant human OATP1B1/SLCO1B1 and OATP1B3/SLCO1B3 in the presence/absence of OATP substrates taurocholate (TC) and bromosulfophthalein (BSP) and measuring PP-inhibition and cytotoxicity. Control vector expressing HEK293 were resistant to MC cytotoxicity, while TC and BSP competition experiments reduced MC cytotoxicity in HEK293-OATP transfectants, thus confirming the requirement of OATPs for trans-membrane transport. Despite comparable PP-inhibiting capabilities, MCLW and -LF elicited cytotoxic effects at lower equimolar concentrations than MCLR and MCRR, hence suggesting congener selective transport into HEK293-OATP transfectants and primary human hepatocytes. Primary human hepatocytes appeared one order of magnitude more sensitive to MC congeners than the corresponding HEK293 -OATP transfectants. Although the latter maybe due to a much lower level of PPs in primary human hepatocytes, the presence of OATPs other than 1B1 or 1B3 may have added to an increased uptake of MCs. In view of the high sensitivity of human hepatocytes and currently MCLR-only based risk calculations, the actual risk of human MC-intoxication and ensuing liver damage could be underestimated in freshwater cyanobacterial blooms where MCLW and-LF predominate.     

炭疽杆菌双重实时荧光PCR检测方法的建立

目的 建立同时检测炭疽杆菌capA基因、PA基因的双重实时定量荧光PCR方法,用于应对突发传染病疫情和流行病学调查、突发公共卫生事件应急处置的早期检测及防范生物恐怖威胁.方法 设计和合成分别针对炭疽杆菌capA基因、PA基因的引物对和荧光双标记探针,构建质粒标准品,通过优化探针、引物浓度、反应体系试剂组分等参数,建立可同时检测capA基因、PA基因的双重实时荧光PCR方法,测试方法的灵敏度和特异性,并在实战检测中应用.结果 双重实时荧光定量PCR的炭疽杆菌capA基因、PA基因检测的灵敏度分别可达到每反应5和50拷贝,并具有良好的特异性,在实战应用中亦经过考验.结论 双重实时荧光定量PCR技术具有可以同时筛查、经济、快速、特异性强等优点,在炭疽杆菌检测方面有良好应用价值.     

荧光PCR法检测人胃组织中幽门螺旋杆菌核酸的实验研究

目的 探讨荧光定量PCR方法检测人胃组织中幽门螺杆菌的意义.方法 收集399例上消化道疾病患者的胃粘膜活检标本.其中食管炎8例,食管溃疡5例,食管癌15例,胃炎301例,胃溃疡30例,胃癌5例,十二指肠炎4例,十二指肠溃疡29例,十二指肠癌2例.核酸测序作为金标准方法,分析荧光定量PCR方法检测胃粘膜幽门螺杆菌的价值....     

A new simple and reliable high-performance liquid chromatography-diode array detection method for the simultaneous quantitative and fingerprint analyses of Salvia przewalskii

In the present study, we developed a novel high-performance liquid chromatography-diode array detection (HPLC-DAD) method for the simultaneous determination and fingerprinting of 15 components in Salvia przewalskii. The method had good linearity, precision, stability and recovery. Chromatographic fingerprints were determined by HPLC-DAD using rosmarinic acid peaks as references, and 17 common peaks were selected. The similarity indexes calculated based on similarity system theory of the 10 samples were higher than 0.948, indicating good correlation among the common peaks. The chromatograms distinguished S. przewalskii from Salvia miltiorrhiza and identified the origins of S. przewalskii. These results suggested that the proposed method was suitable for S. przewalskii quality control.     

An advanced technique for immuno-labelling of microcystins in cryosectioned cells of Microcystis aeruginosa PCC 7806 (cyanobacteria): implementations of an experiment with varying light scenarios and culture densities.

The intracellular localisation of cyanobacterial toxins might well indicate production sites and possible shifts to destination points, thus giving information on possible functions of these toxins within algal cells or at the ecological level beyond. By preparing cells of Microcystis aeruginosa PCC 7806 by cryofixation/cryosectioning and using purified high quality antibodies for immunogold-localisation, excellent ultrastructural integrity and labelling of microcystins was shown. Compared to conventional techniques, including organic solvents, possible dislocation/extraction was significantly minimised, hence, the labelling density was enhanced and the labelling pattern changed. The microcystins were mainly localised within the inner nucleoplasmic area and accumulations of epitopes could be detected around/within intracellular inclusions, such as polyphosphate bodies and carboxysomes. Photosynthetic active radiation (PAR) had a significant effect on microcystin biosynthesis, and the medium light intensity of 25 microE m(-2) s(-1) induced the highest intracellular microcystin contents (up to 160 epitopes per cell and 26 epitopes per microm2). The restriction of the full light spectrum to blue (400-500 nm) or red (>610 nm) wavelengths did not result in any significant effect on microcystin production. However, the subcultures harvested at higher optical densities (>0.5) revealed significantly higher microcystin labelling compared to the less dense cell cultures (OD < 0.5). Altogether, the possibility was discussed whether microcystin might function as an inhibitor of RUBISCO under conditions of C-limitations. The effects of light intensity and cell suspension density on intracellular microcystin shown by immuno-detection matched the pattern of microcystin concentrations determined in parallel by HPLC and ELISA.     

TaqMan荧光定量PCR检测细胞中逆转录病毒的方法验证

目的 验证Taqman荧光定量PCR检测生物制品生产用细胞中逆转录病毒的方法。方法 从专属性、检测限、线性、重现性、耐用性、准确性、精密度几个方面验证该方法在质量控制中的可行性。结果 该方法可检测2BS细胞、Vero细胞中的逆转录病毒,检测限可达1.0×10³ pU/μl逆转录酶。该法线性良好,决定系数＞0.960。该方法重现性好。试剂经5次冻融,体系在室温放置1 h均不影响实验结果。外加标准品的回收率均高于70%,相对标准偏差＜5%。结论 Taqman荧光定量PCR法可用于检测用于2BS细胞和Vero细胞是否被逆转录病毒污染。     

肠道病毒71型抗原定量检测方法的建立

目的 建立肠道病毒71型(enterovirus 71,EV71)抗原的定量检测方法,用于EV71疫苗生产过程中EV71抗原含量的监测.方法 用EV71抗原免疫新西兰兔制备抗EV71多克隆抗体,纯化后用辣根过氧化物酶标记.采用双抗体夹心ELISA法建立抗原检测系统.以EV71国家抗原标准品为定量标准,建立剂量反应曲线,确定该方法的线性范围和定量限,并对该方法的特异性、精密度、准确性、稳定性及适用性等进行验证.结果 建立的ELISA法的线性范围为5～80 U/ml,定量限为5 U/ml,线性决定系数均大于0.990 0;不同浓度样品回收率为85.0％～110.0％,变异系数均小于15％;置于2～8℃及37℃3、6d的抗体包被板对不同浓度样品的检测值变异系数均小于15％;该方法可特异性检测EV71原液,与非EV71样品无交叉反应.结论 建立了EV71抗原定量检测方法,为EV71疫苗生产工艺过程的质量控制奠定了基础.     

双抗体夹心ELISA法定量检测左旋多巴

目的建立左旋多巴的酶联免疫定量分析方法。方法以左旋多巴与载体蛋白钥孔戚血蓝素偶联,制备免疫抗原Levodopa-KLH。采用杂交瘤技术制备的特异性抗左旋多巴单克隆抗体作为包被抗体,待测左旋多巴为夹心抗原,免疫抗原Levodopa-KLH免疫新西兰兔得到的多克隆抗体为检测抗体,建立了一种定量测定左旋多巴的双抗体夹心ELISA方法。结果左旋多巴浓度在40～2 000 ng/mL范围内呈良好线性关系,Y=0.8367 X+0.3423,相关系数r2=0.993 3,检测限为20 ng/mL。经方法学考核,批内、批间变异系数分别为9.53%和12.77%,平均回收率为87.86%,与卡比多巴、多巴胺、异丙肾上腺素、去甲肾上腺素、肾上腺素、维生素C、5-羟色胺、金刚烷胺基本无交叉反应,健全性分析表明,人血清稀释倍数对该方法无影响,8 d连续检测标准曲线表明稳定性良好。结论这种定量检测左旋多巴的双抗体夹心ELISA方法,灵敏度高,重复性好,为左旋多巴研究提供了定量检测的方法,并为药代动力学、临床血药浓度监测提供备选方法。     

TaqMan MGB探针法实时荧光定量PCR快速检测支原体的研究

目的:建立特异、敏感、快速检测支原体的TaqMan MGB探针实时荧光定量PCR方法。方法:针对支原体16S rRNA基因的保守区设计特异性引物和探针,建立支原体TaqMan MGB探针实时荧光定量PCR方检测方法,验证方法的特异性、敏感性和稳定性。对2008～2010年期间在北京采集的680份小型猪、小鼠、大鼠样本中的支原体进行检测,同时进行分离培养和常规PCR检测。结果:建立的TaqMan MGB探针实时荧光定量PCR方法对支原体的检测具有高度的特异性,对空肠弯曲菌、支气管鲍特杆菌、肺炎克雷伯杆菌、侵肺巴斯德氏菌、大肠埃希菌、铜绿假单胞菌、肺炎链球菌、乙型溶血性链球菌均无交叉反应,检测的灵敏度达9.2拷贝。标准曲线显示各浓度范围内具有良好的线性关系,相关系数为0.999,斜率为-3.328,TaqManMGB探针实时荧光定量PCR效率为100%。对680份动物样本进行检测,结果TaqMan MGB探针实时荧光定量PCR和常规PCR均能检出77份支原体阳性样本,但分离培养未能检出支原体阳性样本。结果显示,建立的TaqMan MGB探针实时荧光定量PCR方法比细菌分离培养方法更敏感,能够直接从动物样本中检出支...     

Production of antibodies against microcystin-RR for the assessment of purified microcystins and cyanobacterial environmental samples.

Microcystins (MC) are cyanobacterial hepatotoxins responsible for animal-poisoning and human health incidents. Immunoassays provide a sensitive means to detect these toxins, although cross-reactivity characteristics of different antibodies are variable, and most antibodies have been produced against MC-LR. Here, we have produced the first polyclonal antibodies against the commonly occurring variant, MC-RR, and compared them with MC-LR antibodies for the analysis of purified MCs and cyanobacterial environmental samples. Both antisera cross-reacted with all MCs tested, and with the related cyanobacterial hepatotoxin nodularin-R, but not with non-toxic cyanobacterial peptides. In general, better cross-reactivity characteristics were observed with the MC-RR antisera and limits of quantification were lower for most variants, with all MCs tested and nodularin-R having limits of quantification of 0.31 nM or below. The antisera had different affinities to mixtures containing pooled MC-LR and MC-RR, with MC-LR antisera underestimating total MC concentration when MC-RR represented over 70% of the total MC pool. Both antisera correlated well with HPLC-UV data when incorporated into ELISAs to screen previously characterised environmental samples from Aland, Finland. MC-RR antisera are useful for screening samples containing multiple MCs, and particularly for samples primarily containing MC-RR variants.     

荧光定量PCR检测TRECs的标准品质粒和标准曲线的构建

目的 构建荧光定量PCR检测T细胞受体重排切除环(TRECs)的标准品质粒和标准曲线.方法 对TCRδ基因进行序列分析,设计一对引物和探针.提取正常人外周血单个核细胞中的DNA,经普通PCR扩增,产物纯化后与pUCM-T载体连接并转化入大肠杆菌DH5α,筛选得到重组成功的质粒.结果 重组质粒测序后显示目的片段序列正确,表明TRECs基因片段成功克隆.以103～107 copies/ml不同稀释水平的标准品进行荧光定量PCR扩增后,统计学分析显示标准品浓度的对数与Ct值之间存在良好的线性关系(r=-0.998,P＜0.01).结论 所构建的TRECs标准品特异性和线性关系较好.     

Taqman real-time PCR assay based on ORFV024 gene for rapid detection of orf infection

Abstract

In this study, a TaqMan real-time polymerase chain reaction (PCR) assay was developed to detect and quantify orf virus (ORFV) DNA in infected cell culture and clinical samples. Primers and probes were designed to amplify an 87?bp fragment DNA based on the sequence of ORFV024 gene encoding an NF-κB inhibitor of orf virus. The assay was highly specific and sensitive for ORFV DNA and no cross-reactions were detected with any other poxviruses; the sensitivity was 5?fg or 15 copies of ORFV genomic DNA. Both intra- (1.490?±?1.261%) and inter-assay (1.958?±?0.568%) variabilities were within the acceptable range, indicating the high efficiency and reproducibility of the assay. Further, the assay has shown a relative diagnostic sensitivity and specificity of 100%, when compared to B2L gene-based semi-nested PCR. The assay is simple, rapid, specific and sensitive with a wide potential for rapid field diagnosis of orf in sheep and goats.     

荧光定量聚合酶链反应检测乙型肝炎病毒DNA及其与血清标志物的关系探讨

目的　用荧光定量聚合酶链反应 (fluorescence quantitative polymerase chain reaction,FQ- PCR)方法定量检测血清中乙型肝炎病毒 (hepatitis B virus,HBV)的数量及探讨其与 HBV标志物 (HBV M)表现模式的关系 ,以指导临床。方法　共 2 4 4份临床血清标本 ,HBV DNA定量采用荧光定量 PCR分析系统 ,HBV M采用 EL ISA法。结果　经 FQ- PCR检测 ,99例 HBs Ag(+) / HBe Ag(+) / HBc Ab(+)的标本 ,其血清标本 HBV DNA亦全部阳性 ,平均 HBV DNA拷贝数为 1.82× 10 7copies/ ml;96例 HBs Ag (+) / HBe Ab (+) / HBc Ab (+)的标本 ,其 HBV DNA检出率为 6 6 .7% (6 4例 ) ,平均拷贝数为 1.82× 10 4 copies/ m l;11例 HBs Ag (+) / HBc Ab (+)的标本其 HBV DNA检出率为 6 3.6 % (7例 ) ,平均拷贝数为 7.94× 10 4 copies/ ml。结论　血清 HBV DNA水平与 HBV M表现模式有关 ,HBs Ag (+) / HBe Ag (+) / HBc Ab (+)的标本 HBV DHA值显著高于 HBs Ag (+) / HBe Ab (+) / HBc Ab (+)的标本和 HBs Ag (+) / HBc Ab (+)的标本 ,提示 HBs Ag与 HBe Ag的存在影响 HBV DNA水平。 FQ- PCR能实现准确定量 ,可以检测 HBV的真实感染和复制情况 ,对于乙型肝炎的临床诊断、治疗方案的选择和疗效考察有较大的指导意义     

A nanoparticle-based bio-barcode assay for ultrasensitive detection of ricin toxin

The ultrasensitive bio-barcode amplification assay (BCA) technique was developed for the specific detection of the A chain of ricin toxin. The target antigen A chain was first captured by gold nanoparticles (GNPs) coated with polyclonal antibodies. Magnetic microparticles (MMPs) coated with A chain monoclonal antibody were then added to form a sandwich immuno-complex. After the immuno-complex was formed, signal DNA annealed to DNA strands covalently bound to the GNPs were released by heating and characterized by PCR and real-time fluorescence PCR. A detection limit of 1 fg/ml was measured for A chain, six orders of magnitude more sensitive than that of conventional antigen-capture ELISA. The coefficient of variation (CV) of intra-assay and inter-assay ranged from 3.39% to 6.84%. The BCA can detect the A chain in milk and water mimic samples. In the following work it is demonstrated that this assay is a highly sensitive method for the detection of ricin proteins that could be adapted to measure other proteins.     

Robustness of digital PCR and real-time PCR against inhibitors in transgene detection for gene doping control in equestrian sports

Gene doping is a threat to fair competition in sports, both human and equestrian. One method of gene doping is to administer exogenous genetic materials, called transgenes, into the bodies of postnatal humans and horses. Polymerase chain reaction (PCR)-based transgene detection methods such as digital PCR and real-time PCR have been developed for gene doping testing in humans and horses. However, the significance of PCR inhibitors in gene doping testing has not been well evaluated. In this study, we evaluated the effects of PCR inhibitors on transgene detection using digital PCR and real-time PCR against gene doping. Digital PCR amplification was significantly inhibited by high concentrations of proteinase K (more than 0.1 μg/μl), ethylenediaminetetraacetic acid (more than 5 nmol/μl), and heparin (more than 0.05 unit/μl) but not by ethanol or genomic DNA. In addition, phenol affected droplet formation in the digital PCR amplification process. Real-time PCR amplification was inhibited by high concentrations of phenol (more than 1% v/v), proteinase K (more than 0.001 μg/μl), ethylenediaminetetraacetic acid (more than 1 nmol/μl), heparin (more than 0.005 unit/μl), and genomic DNA (more than 51.9 ng/μl) but not by ethanol. Although both PCR systems were inhibited by nearly the same substances, digital PCR was more robust than real-time PCR against the inhibitors. We believe that our findings are important for the development of better methods for transgene detection and prevention of false negative results in gene doping testing.