4种植物源性成分多重real-time PCR检测方法的建立及其在食用淀粉中的应用

建立一种可同时快速检测红薯、木薯、马铃薯、玉米源性成分的多重实时聚合酶链式反应(real-time polymerase chain reaction,real-time PCR)方法。分别以红薯g3pdh基因、木薯g3pdh基因、马铃薯UGPase基因、玉米zSSIIb基因为靶基因设计特异性引物和TaqMan探针,以18S rRNA基因为内参基因,建立多重real-time PCR方法,开展方法学验证,并对不同掺入比例模拟样品和实际淀粉样品进行检测。结果显示,该方法具有高通量、特异性强、灵敏度高等优点。与15种非目标源性均无交叉反应;对目标DNA的检测灵敏度可达到3×10^(-3) ng/μL,且具有良好的线性关系和扩增效率;对淀粉样品的检出限可达0.1%,对50份实际样品进行检测,结果与参比方法一致,说明建立的多重real-time PCR法可用于食用淀粉种类掺假鉴别检测。

马乳酒样乳杆菌马乳酒样亚种real-time PCR检测方法的建立与应用

本研究建立了一种特异性实时聚合酶链式反应(real-time polymerase chain reaction,real-time PCR)检测方法,根据模式菌株马乳酒样乳杆菌马乳酒样亚种ZW3的16S rDNA序列和全基因组序列设计筛选特异性引物,采用SYBR Green I荧光染料建立real-time PCR方法,并对方法的特异性、灵敏度、重复性和混合体系等进行检测。结果表明,本研究所建立的方法特异性强、灵敏度高、重复性好,建立real-time PCR的标准曲线,其决定系数R2为0.965,具有良好的线性关系,且在马乳酒样乳杆菌马乳酒样亚种及混合体系中可以特异性检出。综上,本研究建立的real-time PCR法可以快速、准确地检测马乳酒样乳杆菌马乳酒样亚种,为马乳酒样乳杆菌的特异性定性定量检测提供了一种新的方法。

垂体后叶粉中3种动物源性成分多重real-time PCR检测方法的建立及应用

目的基于三重实时聚合酶链式反应(real-time polymerase chain reaction,real-time PCR)技术同时快速检测垂体后叶粉中的猪、牛、羊性动物源性成分。方法采用CTAB法提取样品及对照品DNA,以线粒体基因为靶基因设计并合成三重real-time PCR的引物探针,并对建立方法进行验证,用于检测垂体后叶粉样品是否与标识一致。结果猪、牛、羊源性成分的最低检测浓度为10 pg/μL,采用建立的方法检测3批垂体后叶粉样品,均只检测出猪源性成分。结论建立的方法可用于同时检测垂体后叶粉中的猪、牛、羊源性成分,可为相关工作提供技术支持。

4种动物源性成分多重real-time PCR检测方法的建立及其在驴肉制品检测中的应用

建立一种同时快速检测驴、马、猪及鸭源性成分的四重实时聚合酶链式反应(real-time polymerase chain reaction,real-time PCR)方法。分别以4种源性成分的Nad5、ATpase6、ATP8、cytb基因为靶基因设计特异性引物和TaqMan探针,以18S rRNA基因为内参基因,建立多重real-time PCR方法,并对该方法进行方法学验证,同时对不同掺入比例模拟样品、不同加工工艺模拟样品和实际驴肉样品进行检测。结果显示,该方法具有高通量、特异性强、灵敏度高等优点。当Ct值≤35.0时,方法对16种非目标源性具有良好特异性;灵敏度可检测到质量浓度为2×10^(-4)ng/μL的模板DNA;对生肉的检出限为肉含量的0.001%,对熟肉制品的检出限为肉含量的0.01%;对100份实际样品进行检测,结果与标准方法一致,说明建立的多重real-time PCR法可用于肉及肉制品中常见掺假源性成分的检测。

Development and application of a real-time polymerase chain reaction method for Campylobacter jejuni detection

AIM:To develop a real-time polymerase chain reaction(PCR) method to detect and quantify Campylobacter jejuni(C.jejuni) from stool specimens.METHODS:Primers and a probe for real-time PCR were designed based on the specific DNA sequence of the hipO gene in C.jejuni.The specificity of the primers and probe were tested against a set of Campylobacter spp.and other enteric pathogens.The optimal PCR conditions were determined by testing a series of conditions with standard a C.jejuni template.The detection limits were obtained using purified DNA from bacterial culture and extracted DNA from the stool specimen.Two hundred and forty-two specimens were analyzed for the presence of C.jejuni by direct bacterial culture and real-time PCR.RESULTS:The optimal PCR system was determined using reference DNA templates,1 × uracil-DNA glycosylase,3.5 mmol/L MgCl 2,1.25 U platinum Taq polymerase,0.4 mmol/L PCR nucleotide mix,0.48 μmol/L of each primer,0.2 μmol/L of probe and 2 μL of DNA template in a final volume of 25 μL.The PCR reaction was carried as follows:95 ℃ for 4 min,followed by 45 cycles of 10 s at 95 ℃ and 30 s at 59 ℃.The detection limit was 4.3 CFU/mL using purified DNA from bacterial culture and 10 3 CFU/g using DNA from stool specimens.Twenty(8.3%,20/242) C.jejuni strains were isolated from bacterial culture,while 41(16.9%,41/242) samples were found to be positive by realtime PCR.DNA sequencing of the PCR product indicated the presence of C.jejuni in the specimen.One mixed infection of C.jejuni and Salmonella was detected in one specimen and the PCR test for this specimen was positive.CONCLUSION:The sensitivity of detection of C.jejuni from stool specimens was much higher using this PCR assay than using the direct culture method.

Detection of the Pandemic H1N1/2009 Influenza A Virus by a Highly Sensitive Quantitative Real-time Reverse-transcription Polymerase Chain Reaction Assay

A quantitative real time reverse-transcription polymerase chain reaction （qRT-PCR） assay with specific primers recommended by the World Health Organization （WHO） has been widely used successfully for detection and monitoring of the pandemic H1N1/2009 influenza A virus. In this study, we report the design and characterization of a novel set of primers to be used in a qRT-PCR assay for detecting the pandemic H1N1/2009 virus. The newly designed primers target three regions that are highly conserved among the hemagglutinin （HA） genes of the pandemic HlN1/2009 viruses and are different from those targeted by the WHO-recommended primers. The qRT-PCR assays with the newly designed primers are highly specific, and as specific as the WHO-recommended primers for detecting pandemic H1N1/2009 viruses and other influenza viruses including influenza B viruses and influenza A viruses of human, swine, and raccoon dog origin. Furthermore, the qRT-PCR assays with the newly designed primers appeared to be at least 10-fold more sensitive than those with the WHO-recommended primers as the detection limits of the assays with our primers and the WHO-recommended primers were 2.5 and 25 copies of target RNA per reaction, respectively. When tested with 83 clinical samples, 32 were detected to be positive using the qRT-PCR assays with our designed primers, while only 25 were positive by the assays with the WHO-recommended primers. These results suggest that the qRT-PCR system with the newly designed primers represent a highly sensitive assay for diagnosis of the pandemic HIN1/2009 virus infection.

ON MARKOV CHAINS IN SPACE-TIME RANDOM ENVIRONMENTS

In Section 1, the authors establish the models of two kinds of Markov chains in space-time random environments (MCSTRE and MCSTRE(+)) with abstract state space. In Section 2, the authors construct a MCSTRE and a MCSTRE(+) by an initial distribution Φ and a random Markov kernel (RMK) p(γ). In Section 3, the authors es-tablish several equivalence theorems on MCSTRE and MCSTRE(+). Finally, the authors give two very important examples of MCMSTRE, the random walk in spce-time random environment and the Markov br...

Expression of cellular fibronectin mRNA in adult periodontitis and peri-implantitis: a real-time polymerase chain reaction study

Cellular fibronectin （cFn） is a type of bioactive non-collagen glycoprotein regarded as the main substance used to maintain periodontal attachment. The content of cFn in some specific sites can reflect the progress of periodontitis or peri-implantitis. This study aims to evaluate the expression of cFn messenger RNA （mRNA） in tissues of adult periodontitis and peri-implantitis by real-time fluorescent quantitative polymerase chain reaction （PCR） and to determine its clinical significance. A total of 30 patients were divided into three groups of 10： healthy, adult periodontitis and peri-implantitis. Periodontal tissue biopsies （1 mmx I mmx I mm） from each patient were frozen in liquid nitrogen. Total RNA was extracted from these tissues, and the content, purity and integrity were detected. Specific primers were designed according to the sequence, and the mRNA expression levels of cellular fibronectin were detected by real-time PCR. The purity and integrity of the extracted total RNA were both high, and the specificity of amplified genes was very high with no other pollution. The mRNA expression of cFn in the adult periodontitis group （1.526＋0.441） was lower than that in the healthy group （3.253＋0.736）. However, the mRNA expression of cFn in the peri-implantitis group （3.965＋0.537） was significantly higher than that in the healthy group. The difference revealed that although both processes were destructive inflammatory reactions in the periodontium, the pathomechanisms were different and the variation started from the transcription level of the cFn gene.

Real-time polymerase chain reaction for the diagnosis of necrotizing herpes stromal keratitis

AIM： To design, optimize and validate a rapid,internally controlled real-time polymerase chain reaction（RT-PCR） test for herpes simplex virus（HSV） in the diagnosis of necrotizing herpes stromal keratitis.· METHODS： Tears alone or together with corneal epithelium scrapings from 30 patients（30 eyes）suspected of necrotizing herpes stromal keratitis were tested for HSV DNA by RT-PCR. The samples were collected during the first visit and then on the subsequent 7, 14, 28, 42, and 56 d. The symptoms of the patients were scored before treatment to determine the correlation between HSV concentration in the corneal epithelium scrapings and clinical scores.·RESULTS： The positive rate（46.4%） in the corneal epithelium group before the therapy was significantly higher than that（13.3%） in the tears group（P =0.006）.There were 13 positive HSV patients before the therapy,the concentration of HSV DNA in corneal epithelium scrapings group was significantly higher than that in the tears group（paired t-test, P =0.0397）. Multilevel mixedeffects model analysis showed that the difference between the corneal epithelium scrapings group and the tears group was statistically significant（P =0.0049）. The Spearman rank correlation analysis indicated a positive correlation between the HSV concentration in the corneal epithelium scrapings and clinical scores before the treatment（r =0.844, P〈 0.0001）.· CONCLUSION： RT-PCR appears to be a powerful molecular tool for the diagnosis of necrotizing herpes stromal keratitis.

Rapid genotyping of human rotavirus using SYBR green real-time reverse transcription-polymerase chain reaction with melting curve analysis

AIM: To develop a real-time reverse transcriptionpolymerase chain reaction(RT-PCR) assay to genotype rotavirus(G and P) in Alberta from January 2012 to June 2013. METHODS: We developed and validated a different approach to perform rotavirus G and P genotyping using a two-step SYBR green RT-PCR(rt-g PCR) by selecting genotype-specific primers of published conventional RT nested PCR(cn RT-PCR) assay and optimizing the amplification conditions. c DNA was first synthesized from total RNA with Super Script? Ⅱ reverse transcriptase kit followed by amplication step using monoplex SYBR green real-time PCR. After the PCR reaction, melting curve analysis was used to determine specific genotype. Sixteen samples previously genotyped using cn RT-PCR were tested using the new assay and the genotyping results were compared as sensitivity analysis. Assay specificity was evaluated by testing other gastroenteritis viruses with the new assay. The amplicon size of each available genotype was determined by gelelectrophoresis and DNA sequences were obtained using Sanger-sequencing method. After validation and optimization, the new assay was used to genotype 122 pediatric clinical stool samples previously tested positive for rotavirus using electron microscopy between January2012 and June 2013.RESULTS: The new rt-g PCR assay was validated and optimized. The assay detected G1 to G4, G9, G12 and P[4] and P[8] that were available as positive controls in our laboratory. A single and clear peak of melting curve was generated for each of specific G and P genotypes with a Tm ranging from 80 ℃ to 82 ℃. The sensitivity of rt-g PCR was comparable to cn RT-PCR with 100% correlation of the 16 samples with known G and P genotypes. No cross reaction was found with other gastroenteritis viruses. Using the new rt-g PCR assay, genotypes were obtained for 121 of the 122 pediatric clinical samples tested positive for rotavirus: G1P[8](42.6%), G2P[4](4.9%), G3P[8](10.7%), G9P[8](10.7%), G9P[4](6.6%), G12P[8](23.0%), and unknown GP[8](0.8%). For the first time, G12 rotavirus strains were found in Alberta and G12 was the second most common genotype during the study period. Gel electrophoresis of all the genotypes showed expected amplicon size for each genotype. The sequence data of the two G12 samples along with other genotypes were blasted in NCBI BLAST or analyzed with Rota C Genotyping tool(http://rotac.regatools.be/). All genotyping results were confirmed to be correct.CONCLUSION: rt-g PCR is a useful tool for the genotyping and characterization of rotavirus. Monitoring of rotavirus genotypes is important for the identification of emerging strains and ongoing evaluation of rotavirus vaccination programs.

Model of Markov Chains in Space-Time Random Environments

A general framework of stochastic model for a Markov chain in a space-time random environment is introduced, here the environment ξ^＊：={ξ1,x∈N,x∈ X}is a random field. We study the dependence relations between the environment and the original chain, especially the ＂feedback＂. Some equivalence theorems and law of large numbers are obtained.

Manufacturing Supply Chain Optimization Problem with Time Windows Based on Improved Orthogonal Genetic Algorithm

Aim to the manufacturing supply chain optimization problem with time windows,presents an improved orthogonal genetic algorithm to solve it. At first,we decompose this problem into two sub-problems (distribution and routing) plus an interface mechanism to allow the two algorithms to collaborate in a master-slave fashion,with the distribution algorithm driving the routing algorithm. At second,we describe the proposed improved orthogonal genetic algorithm for solving giving problem detailedly. Finally,the examples suggest that this proposed approach is feasible,correct and valid.

Dynamic Simulation and Test Verifcation of Hydraulic Automatic Tensioner for an Engine Timing Chain Drive System

As a fundamental component of an automobile engine’s timing chain drive system, the hydraulic automatic tensioner signifcantly enhances fuel economy while minimizing system vibrations and noise. However, there is a noticeable lack of research on automatic hydraulic tensioners. This study presents a comprehensive calculation approach for the principal parameters of a hydraulic automatic tensioner. An efective method, grounded in hydraulics and multibody dynamics, was introduced for estimating the dynamic response of such a tensioner. The simulation model developed for the hydraulic tensioner is characterized by its rapid dynamic response, consistent operation, and high accuracy. The dynamic behavior of the tensioner was analyzed under varying boundary conditions, using sinusoidal signal excitation. It was observed that the maximum damping force increases with a decreasing leakage gap. Conversely, an increase in oil temperature or air content leads to a decrease in the maximum damping force. The reaction forces derived from these calculations align well with experimental results. This calculation and simulation approach ofers considerable value for the design of innovative hydraulic tensioners. It not only streamlines the design phase, minimizes the number of trials, and reduces product costs, but also provides robust insights for evaluating the performance of hydraulic tensioners.

Performance Evaluation System of Pig Supply Chain Based on Time-Space Perspective and Balanced Score Card(BSC)

The overall structure of live pig supply chain was constructed based on theoretical study and practical investigation, and the performance evaluation sys- tem for supply chain was studied from two perspectives of time and space and balanced score card （BSC）. From the space perspective and BSC, the performance evaluation system composed of four primary indicators （financial dimension, customer dimension, internal business dimension and innovation/learning perspective） and 26 secondary indicators. From the time perspective and BSC, the system could be divided into four stages, including formation stage, development stage, matu- rity stage and recession stage, with a total of 30 indicators.

Waiting times and stopping probabilities for patterns in Markov chains

Suppose that C is a finite collection of patterns. Observe a Markov chain until one of the patterns in C occurs as a run. This time is denoted by τ. In this paper, we aim to give an easy way to calculate the mean waiting time E(τ) and the stopping probabilities P(τ = τA)with A ∈ C, where τA is the waiting time until the pattern A appears as a run.

Phase Wise Supply Chain Model of EOQ with Normal Life Time for Queued Customers: A Computational Approach

In this paper, we mainly aim to compute the optimal inventory in the phase wise supply chain for queued customers in the interval of lower and upper bounds with particular life of the items. Important performance measures such as total optimal cost of the system and total expected delivery have also been computed by applying the dynamic programming and Drichlet theorem. Finally, numerical demonstration and sensitivity analysis have also been presented to gain the better perspective of the model.

实时荧光定量PCR法对ICU患者痰液标本中鲍曼不动杆菌耐药基因的检测及其评价

目的研究实时荧光定量聚合酶链式反应(PCR)法在重症监护室(ICU)患者痰液标本中检测鲍曼不动杆菌耐药基因的效果。方法选择2021年3月至2022年12月南阳市中心医院纳入的68例ICU患者进入试验,分别收集其痰液标本,通过实时荧光定量PCR法测定标本内鲍曼不动杆菌耐药基因情况,统计鲍曼不动杆菌及耐碳青霉烯类鲍曼不动杆菌的检出率,并观察耐碳青霉烯类鲍曼不动杆菌的药敏试验结果,最后分析OXA-51基因检查结果和耐药基因OXA-23检查结果。结果68例ICU患者的痰液标本中,通过传统培养方式检出鲍曼不动杆菌33株,阳性检出率48.53%;耐碳青霉烯类鲍曼不动杆菌共检出23株,阳性检出率33.82%;基因检测OXA-51阳性显示鲍曼不动杆菌有37株,阳性检出率54.41%;OXA-23阳性显示耐碳青霉烯类鲍曼不动杆菌有25株,阳性检出率36.76%。针对碳青霉烯类药物产生耐药的鲍曼不动杆菌所占比例占75.76%。耐碳青霉烯类鲍曼不动杆菌对于大部分药物耐药,耐药性较低的药物分别有头孢哌酮舒巴坦、米诺环素、替加环素、黏菌素等。传统培养和耐药基因的阳性检出率相比,差异并无统计意义(P>0.05);经Kappa检验显示为0.879,证实两种方式的检查结果的一致性较好。传统培养和耐药基因的阳性检出率相比,差异并无统计意义(P>0.05);经Kappa检验显示为0.712,证实两种方式的检查结果的一致性一般。结论实时荧光定量PCR法的效果明显,可成为鲍曼不动杆菌耐药基因检测的主要方式。

miRNA表达谱在产前诊断胎儿先天性心脏病中的研究

目的:探究微小RNA(microRNA,miRNA)表达谱在产前诊断胎儿先天性心脏病(congenital heart disease,CHD)中的应用。方法:收集2021年1月—2022年12月于天津市中心妇产科医院就诊的30例超声确诊为CHD的孕妇(病例组)和同期10例要求行羊水穿刺的孕妇(对照组),用Illumina测序平台对2组孕妇的羊水上清进行全转录组测序,2组孕妇的全部miRNA进行归一化,分析差异表达的miRNA。从差异表达的miRNA中挑选P<0.05和|log2 FC|>3(差异倍数,Fold Change,FC)的miRNA再在羊水和外周血中进行实时荧光定量聚合酶链反应(real time fluorescence quantitative polymerase chain reaction,RT-qPCR)验证,比较羊水中miRNA测序与RT-qPCR的差异倍数,挑选外周血与羊水表达调控方向一致的miRNA。结果:共发现138个差异表达miRNA,其中85个上调,53个下调。进一步挑选出了15个差异表达的miRNA,羊水中miRNA测序与RT-qPCR结果比较相一致。外周血与羊水中表达调控方向一致的miRNA有2个,分别为miR-222-3p和miR-189-5p,这2个miRNA在病例组母血中表达量较对照组显著上升(均P<0.05)。结论:母血中miRNA作为新的血清学标志物可以初步应用于筛查胎儿CHD。

预售模式下电商平台订货时间与定金决策研究

预售模式延长了产品整体销售周期,这为电商平台的产品订货时间决策带来了新问题。为研究对比提前与延后两种订货时间策略影响下的产品定金、产品价格与电商平台利润,建立两阶段主从博弈模型,分析定金敏感度、尾款敏感度和制造成本对订货时间选择与产品定金决策的影响。结果表明:在延后订货模式中,定金、尾款敏感度对产品订货价格影响相反;在提前订货模式中,只有定金敏感度影响产品订货价格。电商平台预售券/定金策略受消费者尾款敏感度影响。

时序数据的因果关系交互式可视分析

针对时序数据中因果关系检测算法效率低、错误率高、可解释性低的问题,本文提出一种新颖的用于时序数据的因果关系检测模型。该模型整合了泛函贪婪等价搜索(F-GES)模型与格兰杰(Granger)因果关系模型,展开因果关系的抽取和推断,并提出了因果关系可视分析方法,以交互式地分析时序数据中变量间的因果关系。可视分析方法形成了参数视图用于提高因果关系探索效率、因果关系树图用于直观有效地展示变量之间的因果关系、时间视图用于比较原始时序数据、堆叠流图用于帮助用户探索时序数据的层次演变以及平行坐标图用于进行相关性分析。基于真实数据形成的原型系统交互式地验证和总结时序数据中的因果关系,从而更高效地挖掘和理解时序数据中变量之间蕴含的因果规律以帮助决策。