Confusing finding of quantitative fluorescent polymerase chain reaction analysis in invasive prenatal genetic diagnosis:A case report

BACKGROUND Quantitative fluorescent polymerase chain reaction(QF-PCR)is a rapid prenatal diagnostic method for abnormalities on chromosomes 21,18,and 13 and sex chromosomal aneuploidy.However,the value of QF-PCR in diagnosing chromosomal structural abnormalities is limited.In this article,we report a confusing QF-PCR finding in a pregnant woman who underwent amniocentesis.CASE SUMMARY The short tandem repeat marker AMXY(Xp22.2/Yp11.2)located on the sex chromosome exhibited a trisomic biallelic pattern,indicating that the karyotype of the fetus might be 47,XYY.Chromosome analysis performed on cultured amniocytes showed a normal male karyotype of the fetus.Copy number variation sequencing confirmed a 500 kb duplication at Yp11.2-Yp11.2(chrY:6610001_7110000)and a 250 kb duplication at Yp11.2-Yp11.2(chrY:7110001_7360000).CONCLUSION In conclusion,the comprehensive application of different methods could achieve a higher detection rate and accuracy for the prenatal diagnosis of chromosomal disorders through chromosomal testing.

Comparison of direct fecal smear microscopy,culture,and polymerase chain reaction for the detection of Blastocystis sp.in human stool samples

Objective:To compare the sensitivity and specificity of direct fecal smear microscopy,culture,and polymerase chain reaction in the detection of Blastocystis sp.in human stool.Methods:Human stool samples were collected from a community in San Isidro,Rodriguez,Rizal,Philippines.These samples were subjected to direct fecal smear microscopy,culture and polymerase chain reaction to detect the presence of Blastocystis sp.Results:Of the 110 stool samples collected,28(25%)were detected positive for the presence of Blastocystis sp.by two or more tests.Culture method detected the highest number of Blastocystis-positive stool samples(n=36),followed by PCR of DNA extracted from culture(n=26),PCR of DNA extracted from stool(n=10),and direct fecal smear(n=9).Compared to culture,the sensitivity of the other detection methods were 66.7%for PCR from culture and 19.4%for both PCR from stool and direct fecal smear.Specificity of the methods was high,with PCR from culture and direct fecal smear having97.3%,while PCR from stool at 95.9%.Conclusions:In this study,in vitro culture is the best method for detecting Blastocystis sp.in human stool samples.

Direct sequencing of hepatitis C virus cDNA using the product of single primer polymerase chain reaction

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A Few Questions that Should be Clarified in the Polymerase Chain Reaction

The polymerase chain reaction is one of the most useful technical advance and inventions in modern molecular biology. Developed in 1983 by Kary Mullis[1], PCR is now a common and indispensable technique used in medical and biology research labs for a variety of applications[2-3]. A large number of articles related to PCR are available on the internet and other places. People know well about the basic principle and are very familiar with the procedures of the PCR. But, some details were neglected on the numbers of the target sequence and other DNA strands number after 30 to 35 cycles of the PCR. In most papers, the number of newly synthesized DNA strands including target DNA and non target DNA is ambiguous and even wrong. In this paper, highlights were given to the theoretical number of target DNA number in details and the exact number of the target DNA number can be concluded by analysis.

广西道地药材肉桂及阴香的DNA分子鉴定研究

建立一种能够准确鉴别肉桂及阴香的特异性聚合酶链式反应方法,以保障肉桂用药的安全性和有效性。通过对比分析肉桂及阴香的psbA-trnH序列差异找到特异性单核苷酸多态性位点,设计特异性引物,通过优化退火温度、循环次数,评估不同聚合酶种类和不同基因扩增仪等扩增条件对不同来源的肉桂及阴香进行特异性扩增,根据特异性扩增条带进行鉴别。结果表明退火温度为54℃,循环次数为35次时,肉桂经肉桂特异性引物扩增后在100~200 bp处出现特异性条带,阴香无条带;退火温度为56℃,循环次数为40次时,阴香经阴香引物扩增后在200~300 bp处出现特异性条带,肉桂无条带。该研究所建立的特异性PCR方法可以快速准确鉴别出肉桂及阴香,为控制肉桂的质量安全提供参考。

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。

叠氮丙啶-实时荧光聚合酶链式反应-高通量测序技术鉴定冷链食品中多种病原菌

目的 应用叠氮丙啶-实时荧光聚合酶链式反应-高通量测序技术鉴定冷链食品中多种病原菌,构建病原菌分子进化树。方法 以冷链食品中的沙门氏菌、金黄色葡萄球菌、蜡样芽胞杆菌、副溶血性弧菌、单核细胞增生李斯特氏菌5种病原菌作为研究对象,应用叠氮丙啶-实时荧光聚合酶链式反应技术作为冷链食品中病原菌检测初筛手段,应用微生物培养法以及生化鉴定仪器法进行方法比对与结果验证,运用高通量测序以及分子进化树构建作为冷链食品中所分离病原菌的种属地位确证方法。结果 叠氮丙啶-实时荧光聚合酶链式反应技术成功扩增了冷链食品中生活状态病原菌的特征性核酸片段,排除了死亡细菌以及阴性对照菌的干扰,病原菌检出限可达到1×10^(3)CFU/mL,一次反应可检测42份试样,可以在18 h内完成检测工作。在冷链食品中病原菌抽样检测调查中,随机采集的751份冷链食品,共检出62株病原菌,病原菌总体检出率为8.3%(62/751)。通过后续的16S rRNA测序以及葡萄球菌属、弧菌属以及李斯特菌属分子进化树的构建,成功溯源了金黄色葡萄球菌的污染来源并完成病原菌种属定位。结论 本方法特异性好、灵敏度高、检测通量高,为冷链食品及相关食品中病原菌的精确检测与溯源分析提供新的思路与方法。

宏基因二代测序技术在社区获得性肺炎病原体检测中的应用进展

社区获得性肺炎(CAP)是常见的感染性疾病之一。其流行病学特征因宿主和免疫状况而异,病原谱也随着时间和空间分布而迁移。准确及快速识别病原体,开展精准治疗,是提高该病治愈率的关键。常规检测方法包括培养法、抗体及抗原检测、聚合酶链反应(PCR)等,但均具有识别缓慢、检出率低等缺陷,从而延误临床治疗时机。宏基因二代测序技术(mNGS)主要通过核酸提取、PCR扩增、文库构建等步骤对标本中所有微生物进行测序,同时利用大量的生物分析鉴定出病原体。与常规检测方法不同,mNGS具有迅速识别、全方位覆盖、灵敏度高等优点,在临床诊断中逐渐被选用。如今,mNGS已在CAP的诊疗中占据着越来越重要的地位,特别是在一些少见及新型病原微生物的检测上,并对特殊人群的病原体检出也具有一定的优势。然而,mNGS作为一种新型检测手段仍存在一些不足之处,例如,检测结果判读无统一的标准、结果受患者遗传物质影响较大、检测成本高等。将来可通过改进检测前标本的预处理、降低检测成本、简化检测后的结果判读对该技术进行优化,以便全面推广mNGS在临床中应用。

脊髓小脑性共济失调2两家系致病基因及临床特点

目的分析洛阳地区两个脊髓小脑性共济失调(SCAs)家系的致病基因及临床特点。方法收集先证者及其家系成员的临床资料。提取外周静脉血DNA,采用聚合酶链反应(PCR)结合琼脂糖凝胶电泳技术对两个家系先证者进行SCA1、2、3、6、7、12、17和DRPLA亚型的筛选。亚型初步确定后对目的片段进行Sanger测序,得到确认后对家系其他成员进行验证。结果家系1和家系2先证者经检测均为SCA2亚型,致病等位基因CAG重复次数分别为44和38次,随后的家系验证结果显示家系1中检测到致病基因携带者3人,家系2中检测到致病基因携带者1人。先证者均以行走不稳为主要症状,部分成员伴言语不清、记忆力下降。结论联合应用PCR和Sanger测序方法确诊了洛阳地区两个SCA2家系,家族性的行走不稳是其主要临床特点。

宏基因组二代测序在实体器官移植感染防控中的应用

器官移植已成为多种终末期疾病的有效治疗手段,但器官移植受者术后需长期服用免疫抑制药,导致免疫功能低下,使得细菌、病毒和真菌感染的发生率相对较高。以病原学培养、免疫学检测和聚合酶链反应为代表的传统微生物检测方法被广泛用于感染检测,但存在耗时长、需预先假定病原体等问题。宏基因组二代测序由于具有病原体检出率高、对病原谱检测全面的优点,近年来被广泛应用于器官移植领域的感染防控。本文就宏基因组二代测序技术在实体器官移植感染防控上的应用现状进行综述,以期对移植相关感染的诊断和治疗提供参考。

Relationship between autoimmune hepatitis and HLA-DR4 and DRβ allelic sequences in the third hypervariable region in Chinese

AIM To analyze the association of HLA-DRBl with autoimmune hepatitis (AIH) in patients from China.``METHODS In .32 patients and 45 healthy controls,polymerase chain reaction amplification with sequencespecific primers (PCR-SSP) was performed to examine the association of certain alleles or polymorphic sequences of HLA-DRB1 with AIH.``RESULTS HLA-DRB1 typing by PCFLSSP showed that DR4had a significantly increased frequency among patients with AIH versus healthy control (46.9% versus 20.8%;relative risk 3.35, P=0.014). In subtypes of DR4, there was a trend of increase in the gene frequency of DRB10405 in patients with AIH versus healthy controls (21.9%vs 6.3%, P=0.04, but Pc 0.08). In addition, asignificant increase was found in the alleles frequency encoding QRRAA from the third hyperpolymorphic region of DR4 in the patients with AIH (86.7% of DR4 positive patients vs 40.0% in DR4 positive controls, P 0.016, Pc =0.028. RR 9.75).``CONCLUSION AIH in Chinese is associated with HLADR4. There is a relationship between QRRAA sequence within the third hyperpolymorphic region of the DRB allele and AIH in Chinese.

DETECTION OF HUMAN PAPILLOMAVIRUS TYPES 16, 18 DNA RELATED SEQUENCES IN BRONCHOGENIC CARCINOMA BY POLYMERASE CHAIN REACTION

In studying the relationship between human papillomavirus (HPV) and bronchogenic carcinoma, 'high-risk' HPV 16, 18 DNA sequences were detected in samples from 50 lung cancer patients, 18 patients with benign pulmonary diseases and 4 fetal lung tissues by polymerase chain reaction (PCR) and dot-blot hybridization with biotin-labelled probes. The results showed that HPV 16, 18 DNA related sequences were found in 32% of lung cancer specimens, with 10 cases of HPV 16, 5 cases of HPV 18 and 1 case of both types. 48.15% (13 / 27) of squamous cell carcinomas were shown to be positive for HPV 16, 18 DNA. In addition, two adenocarcinomas and one small cell carcinoma were positive for HPV 16 DNA. No specimens from benign diseases tissues and fetal lung tissues showed positive results. These results suggest that primary bronchogenic carcinoma is related to HPV infection.

Sequence Analysis of Attachment Gene of Lumpy Skin Disease and Sheep Poxviruses

In Egypt,protection of cattle against lumpy skin disease (LSD) was carried out using a sheep poxvirus (Kenyan strain) vaccination strategy.In the present study 15 skin nodules from LSD suspected cows and 5 scab samples from sheep pox (SP) suspected sheep were collected.Hyperimmune rabbit sera to Lumpy skin disease virus (LSDV)/Ismailyia88 strain and sheep pox virus (SPV)/ Kenyan vaccinal strain were prepared.The causative agent in the collected samples was identified using immunoflourescence (IF) and immunoperoxidase techniques.Of the 15 skin nodules suspected of LSD,10 showed a positive reaction and 3 out of 5 skin scabs suspected of sheeppox were found to be positive.An antigenic correlation between field skin isolate of LSDV,tissue culture adapted LSDV/Ismailyia88 strain,field skin isolate of SPV and SPV/Kenyan vaccinal strain was studied using prepared hyperimmune sera.Also,nucleotide sequence of the PCR amplified attachment gene fragments of field skin isolate of LSDV,tissue culture adapted LSDV/Ismailyia88 strain,field skin isolate of SPV and SPV /Kenyan vaccinal strain were compared.The results revealed that the four used viruses were antigenically identical.Sequence analysis indicated that field skin LSDV isolate is more related to tissue culture adapted LSDV/Ismailyia88 strain than to vaccinal SPV/ Kenyan strain and the skin isolate of SPV is more closely related to field skin isolate of LSDV than to SPV/Kenyan vaccinal strain.Thus,further study should be applied on the advantage of a LSD vaccine prepared from LSDV in protection of cattle against LSD compared to the commonly used sheep pox vaccine.

Detection of rare mutation of β-thalassemia by direct sequence analysis of the PCR products

A technique of direct sequence analysis of β-globin gene with the products of amplifi-cation by polymerase chain reaction (PCR) was reported and a case of β-thalassemia with therare mutation in Chinese,‘codon 14/15 (+G)’ was detected by this method.After the se-quence of the mutation site was determined,an analysis of the restriction map of the gene anddot blot hybridization with radioactive allele specific oligonucleotide probe was designed to con-firm the result of DNA sequencing.

Confirmation of Pearl Millet-Napiergrass Hybrids Using EST-Derived Simple Sequence Repeat (SSR) Markers

Prospects for deploying perennial grasses that are currently considered leading candidates for dedicated energy crops over large acreages are debatable because of several limitations, including vegetative propagation or small seed size, low biomass production during the first growing season, and incomplete assessments of crop invasiveness risk. Pearl Millet-Napiergrass hybrids (“PMN”;Pennisetum glaucum [L.] R. Br. × P. purpureum Schumach.), in contrast, are large-seeded, sterile feedstocks capable of high biomass production during establishment year. Novel methods are warranted for confirmation of PMN hybrids, as traditional morphological observations can be inconclusive and chromosome number determination using cytological methods is laborious and time consuming. Six putative PMN lines were produced in this study, and 10 progeny from each line were evaluated using morphological traits, seed fertility, flow cytometry, and expressed sequence tag-simple sequence repeat (EST-SSR) markers. All putative hybrid lines were sterile and failed to produce seed. The PMN hybrids could not be distinguished from either parent using flow cytometry due to highly similar nuclear genome DNA contents. A number of paternal napiergrass-specific EST-SSRs were identified for each PMN line, and four paternal-specific EST-SSRs conserved across all napiergrass accessions were selected to screen the putative PMN hybrids. These EST-SSRs confirmed that all F1 individuals analyzed were PMN hybrids. The use of paternal-specific markers therefore provides a valuable tool in the development of both “Seeded-yet-Sterile” biofuel PMN feedstocks and additional PMN cultivar-and parental species-specific markers.

Sequence determination of exp-1 Gene of Plasmodium Falciparum Isolate FCC1 /HN

目的 测定恶性疟原虫FCCl／HN株exp-1基因序列。方法 根据exp-1基因已知序列设计合成1对引物，用PCR技术从FCCl／HN株基因组DNA中扩增exp-1基因；将exp-1基因克隆入pMD-18T载体，转化大肠杆菌JMl09感受态细胞，铺x—gal LB平板；挑取阳性菌落，用酶切，PCR扩增进行鉴定。以正确的重组质粒为模板，用双脱氧链末端终止法测定exp-1基因序列。结果 从恶性疟原虫FCCl／HN株基因组DNA中获取exp-1基因，成功克隆入pMD-18T载体；测序表明FCCl／HN株exp-1基因全长937bp，编码162个氨基酸。结论 克隆了恶性疟原虫FCCl／HN株exp-1基因，并测定了其核苷酸序列，为进-步研究其功能奠定基础。

Cloning, sequencing and analyzing of the heavy chain V region genes of human polyreactive antibodies

The heavy chain variable region genes of 5 human polyreactive mAbs generated in our laboratory have been cloned and sequenced using polymerase chain reaction (PCR) technique. We found that 2 and 3 mAbs utilized genes of the VHIV and VHIII families, respectively. The former 2 VH segments were in germline configuration. A common VH segment, with the best similarity of 90.1 % to the published VHIII germline genes, was utilized by 2 different rearranged genes encoding the V regions of other 3 mAbs. This strongly suggests that the common VH segment is a unmutated copy of an unidentified germline VHIII gene. All these polyreactive mAbs displayed a large NDN region (VH-D-JH junction). The entire H chain V regions of these polyreactive mAbs are unusually basic. The analysis of the charge properties of these mAbs as well as those of other poly- and mono- reactive mAbs from literatures prompts us to propose that the charged amino acids with a particular distribution along the H chain V region,especially the binding sites (CDRs), may be an important structural feature involved in antibody polyreactivity.

CNV-seq结合QF-PCR在孕早期流产物检测中的临床应用价值

目的:探讨拷贝数变异测序(CNV-seq)结合定量荧光聚合酶链反应(QF-PCR)在孕早期流产物遗传学检测中的临床应用价值。方法:收集2019年1月至2022年2月在广东省妇幼保健院就诊的孕早期(13周以内)孕妇流产物组织样本,通过CNV-seq结合QF-PCR检测流产物组织的染色体拷贝数变异情况,分析其中染色体拷贝数异常变异的分布及发生率并评估其临床价值。结果:4145例孕早期流产物组织样本中,65.01%(2695/4145)样本提示结果异常,包括51.97%(2154/4145)非整倍体、7.04%(292/4145)三倍体、3.98%(165/4145)部分非整倍体、0.70%(29/4145)同源单亲二倍体、0.05%(2/4145)四倍体以及1.28%(53/4145)微缺失/重复。在所有异常结果中,10M以上的大片段拷贝数异常占96.96%(2613/2695)。在1.97%(53/2695)的孤立性亚显微拷贝数异常中发现了3种复发性致病性亚显微拷贝数异常,分别是22q11.21微缺失/微重复、2qter微缺失(位于2q37.3末端区域内)。结论:CNV-seq结合QF-PCR检测分析孕早期流产物组织中染色体拷贝数变异,可为流产后精准的临床管理和再生育指导提供依据;发现3种潜在的可能与流产相关的致病性亚显微拷贝数异常。

ADAM33基因T2位点多态性与支气管哮喘易感性的关联研究

目的研究解整合素-金属蛋白酶33(ADAM33)基因T2位点多态性与支气管哮喘易感性的关联性。方法选取2019年12月至2020年12月在该院就诊并接受治疗的支气管哮喘患者120例作为研究组,选择同期在该院体检的健康者120例作为对照组,采用等位基因特异性聚合酶链反应技术及DNA测序方法检测两组ADAM33基因T2位点多态性。结果研究组和对照组ADAM33基因T2位点3种基因型均符合Hardy-Weinberg平衡定律(P>0.05)。研究组与对照组ADAM33基因T2位点基因型(AA、AG、GG)频率比较,差异均有统计学意义(χ^(2)=7.001,P<0.05)。ADAM33基因T2位点等位基因中,研究组A等位基因频率(15.42%)低于对照组(23.75%),差异有统计学意义(P<0.05)。ADAM33基因T2位点A等位基因频率增加可降低支气管哮喘患病风险(OR=0.875,P<0.05)。与中度支气管哮喘患者相比,危重、重度支气管哮喘患者ADAM33基因T2位点AG基因型频率差异无统计学意义(P>0.05),中度、重度、危重支气管哮喘患者ADAM33基因T2位点AG基因型频率高于轻度支气管哮喘患者,差异均有统计学意义(P<0.05)。ADAM33基因T2位点AG基因型频率增加是影响支气管哮喘严重程度的高危因素(P<0.05)。结论支气管哮喘与ADAM33基因位点多态性存在关联:ADAM33基因T2位点与支气管哮喘易感性有关,ADAM33基因T2位点A等位基因频率增加可降低支气管哮喘的患病风险,ADAM33基因T2位点AG基因型频率增加是影响支气管哮喘严重程度的高危因素。

Sequence Analysis and Quantitative Detection of Norwalk-like Viruses in Cultured Oysters of China

We isolated 4 Norwalk-like viruses (NLVs) contaminated oysters from 33 Chinese oysters collected from local commer- cial sources of Shandong Province. After amplification of the RNA-dependent RNA polymerase (RdRp) region of NLVs genomes with RT-PCR, the open reading frame 1 (ORF1) of the RdRp was sequenced and subjected to multiple-sequence alignment. The re- sults showed that NLVs in the four isolates belong to genogroup II. The sequence comparison showed that the similarity between four Chinese oyster isolates were higher than 99.0%, which indicated that NLVs prevalent in close areas have high homogeneity in genome sequences. In addition, the most conserved sequences between diverse NLVs were used to design primers and TaqMan probes, then the real-time quantitative PCR assay was performed. According to the standard curve of GII NLVs, the original amounts (copies) of NLVs in positive patient’s fecal isolate, positive Japanese oyster isolate, and the Chinese oyster isolate were 8.9×108, 1.25×108 and 4.7×101 respectively. The detecting limit of NLVs was 1×101 copies. This study will be helpful for routine diagnosis of NLVs pathogens in foods and thus for avoiding food poisoning in the future.