Development and Clinical Application of a Single-tube Nested PCR Method to Amplify the DNA Polymerase Ⅰ Gene of Treponema Pallidum

Objective: To develop a sensitive, specific and simple method for detection of extremely low numbers of T. pallidum in clinical specimens, as a significant addition to the serologic tests for syphilis diagnosis. Methods: Double-tube nested PCR(DN-PCR) and single-tube nested PCR(SN-PCR) assays were performed to amplify specific fragments of the DNA poly-merase I gene(polA) of T. pallidum. Sensitivity and specificity of the two PCR assays were tested. Eighty-six whole blood specimens from persons with suspected syphilis were detected by the two nested PCR methods. The TPPA test was used as a comparison for detecting syphilis in sera from corresponding patients. Results: Only specific amplicons could be obtained during amplification of the T. pallidum polA gene and the detection limit was approximately 1 organism when analyzed on gel by the two PCR methods. Of 86 clinical specimens, 62 were positive by TPPA. Of these, 54 and 51 were positive by the DN-PCR and SN-PCR, respectively, which does not represent a statistically significant difference between the two PCR tests. Of 24 TPPA-negative specimens, 5 were positive by both DN-PCR assay and SN-PCR assay. Conclusion: The SN- polA PCR method is extremely sensitive, specific and easy to perform for detecting low numbers of T. pallidum in clinical blood specimens as a complementary to serology for syphilis diagnosis.

YMDD variants of HBV DNA polymerase gene: Rapid detection and clinicopathoiogical analysis with long-term Iamivudine therapy after liver transplantation

AIM: To look for a rapid low-cost technique for the detection of HBV variants.METHODS: Two patients who underwent orthotopic liver transplantation (OLT) for HBV infection were treated with lamivudine (100 mg daily) and HBV infection recurred in the grafted livers. The patients were monitored intensively for liver enzymes, hepatitis B surface antigen (HBsAg) and HBV DNA in serum. Liver biopsy was performed regularly. HBV DNA in a conserved polymerase domain (the YMDD locus) was amplified from serum of each patient by PCR and sequenced. HBV genotypes were analyzed by restriction fragment length polymorphism (RFLP) of the PCR products generated from a fragment of the polymerase gene.RESULTS: YMDD wild-type HBV was detected in one patient by PCR-RFLP and DNA sequencing 19 mo after OLT, and YIDD mutant-type HBV in the other patient, 16 mo after OLT.CONCLUSION: PCR-RFLP assay is an accurate and simple method for genotyping lamivudine-resistant HBV variants.

A New Tandem Gene Construction Method Involving a Cloning System Using <i>Poxvirus DNA polymerase</i>, and Its Application to Gene Expression

A simple method for constructing polymerized genes using only restriction enzymes and commercially available cloning systems was established. In this system, gel isolations or purifications of target genes after restriction enzyme digestions or PCR amplifications, which often cause errors and mutations in the target gene sequence, are not necessary. To verify the usefulness of this method, one, two, four, eight, and sixteen tandem-repeats of the Green Fluorescent Protein (GFP) expression gene in Escherichia coli were sequentially constructed. Efficacies of the GFP gene expression of those plasmids in E. coli showed an increasing trend in accordance with the copy numbers of the gene. On SDS polyacrylamide gel electrophoresis with Coomassie blue staining, no expressed protein could be seen in E. coli cells harboring plasmids that contained one or two copies of the gene. However, expressed protein bands in E. coli cells were clearly detected with 4 copies of the gene. In quantitative analyses involving green fluorescence intensities per culture volume, the expression level in E. coli with 16 copies of the gene was 36.3-fold higher than that in E. coli with one copy at 22 hours after induction.

Mutation of DNA polymerase p in esophageal carcinoma of different regions

AIM： To observe the variation of DNA polymerase β （polβ） in esophageal carcinoma. METHODS： Thirty specimens containing adjacent normal epithelial tissues were collected from patients in Linzhou region （a high risk area for esophageal squamous carcinoma） and 25 specimens were from a non-high risk area. Total RNA was extracted from the samples and reverse transcription polymerase chain reaction （RT-PCR） was performed. PCR products were cloned and sequenced to investigate the po1β gene with DNASIS and OMIGA. Statistical significance was evaluated using the X^2 test. RESULTS： High-inddence area group： Polβ gene variation was detected in 13 of 30 esophageal carcinoma tissue specimens, and only one variation was found in 30 corresponding adjacent normal tissue specimens. Non high-incidence area group： po1β gene variation was detected in 5 of 25 esophageal carcinoma tissue specimens, and no variation was found in 25 corresponding adjacent normal tissue specimens. The incidence of po1β gene variation observed in the high-incidence area group was significantly higher than in the non-high incidence area group. Two mutation hot spots （454-466 and 648-670 nt） and a 58 bp deletion （177-234 nt） were found. CONCLUSION： Variations of polβ perform different functions between the high-incidence areas and the other areas, and may play a more important role in the high-incidence areas.

THE RADIOBIOLOGIC CHARACTERISTICS OF DNA POLYMERASE β IN HEPATOMAS

To investigate the effects of γ rays on DNA polymerase β properties and its DNA repair functions before or after γ rays exposure, DNA polymerase βactivity, gene expression and mRNA levels in SMMC-LTNM hepatomas horn on nude mice or the samples of the liver cancer tissues from 15 patients were measured with 3H-TTP incorporation test, immunocytochemistry and cytoplasmic dot hybridization analysis, respectively.Irradiation was carried out with 60Co-γ rays at ice bath. It was found that DNA polymerase β activity, gene expression and the amount of mRNA were much higher in hepatoma cells than those in normal hepatocytes (P<0.01). In vitro studies, the enzyme activity both in hepatoma and normal liver cells appeared unchanged within 40 Gy γ-ray exposure. Following whole-body exposure of the nude mice bearing SMMC-LTNM with 2 Gy or 4 Gy of γ rays, DNA polymerase β activity in hepatoma increased temorarily at 48 hours postirradiation, and its gene expression seemed more active.The euzyme mRNA increased to 1.76-fold of the control group. 72 hours after exposure, all of these changes returned to normal levels. DNA polymerase βparticipated in DNA repair synthesis and this effect was different between hepatoma and hepatocytes because there were some biologic differences of the enzyme between hepatoma cells and normal liver cells. These data suggested that DNA polymeraseβactivity, its gene expression and mRNA level in hepatomas could increased temporarily after γ rays exposure, which may facilitate the cells to repair DNA damages from radiation.

The cloning of 3'-truncated preS/S gene from HBV genomic DNA and its expression in transgenic mice

INTRODUCTIONHepatitis B virus (HBV) is regarded as one of themain etiologic factors involved in the developmentof human hepatocellular carcinoma (HCC).The open reading frame (orf)of X gene of HBVencoded a transactivating factor is the evidence thatstrongly supported the notion that the X gene ofHBV DNA integrated in HCC genomic DNA couldcontribute to the carcinogenesis of liver cells byactivation of some related cellular genes

GENE DIAGNOSIS OF HEMOGLOBINOPATHY IN CHINESE BY AMPLIFIED DNA

This paper describes the application of DNA amplification in vitro with the polymerase chain reaction on the prenatal diagnosis of thalassemia syndromes and on detection of HbS and HbD Punjab genes. DNA polymerase chain reaction was performed on lysed amniotic fluid cells or chorionic villus samples without prior DNA extraction and on DNA sampling from dried blood spots on filter paper blotters, α-thalassemia was prenatally diagnosed by direct analysis of amplified fetal target sequences on gel electrophoresis; and β-thalassemia was predicted by Hgi AI RFLP linkage analysis with amplified β-globin DNA. HbS and HbD Punjab genes were identified by Mst Ⅱor Eco RI mapping of the amplified β-globin DNA directly on the electrophoretic gels. The analysis of the amplified DNA does not require radioactive DNA probes and Southern hybridization. The total procedure can be completed within five hours.

Baculovirus RNA Polymerase: Activities, Composition, and Evolution

Baculoviruses are the only nuclear replicating DNA-containing viruses that encode their own DNA-directed RNA polymerase (RNAP). The baculovirus RNAP is specific for the transcription of genes expressed after virus DNA replication. It is composed of four subunits, making it the simplest multisubunit RNAP known. Two subunits contain motifs found at the catalytic center of other RNAPs and a third has capping enzyme functions. The function of the fourth subunit is not known. Structural studies on this unique RNAP will provide new insights into the functions of this enzyme and the regulation of viral genes and may be instrumental to optimize the baculovirus gene expression system.

食管癌高发区人食管癌组织中DNA聚合酶β基因突变检测

目的 :研究林州市食管癌高发区病例的食管癌组织中DNA聚合酶 β基因 (polβ)的突变情况。 方法 :利用PT PCR、SSCP和序列分析对食管癌高发区 5 0例食管癌及癌旁组织标本中polβ基因进行检测。 结果 :5 0例食管癌标本中有 2 2例 polβ发生变异 ,突变率为 4 4 % (2 2 /5 0 ) ;而癌旁组织仅 2例异常 ,突变率为 4 % (2 /5 0 )。突变形式有 :5 8bp(177位到 2 34位 )的基因片段缺失 ;375位A→G(Ile→Val) ,4 5 4位T→C(Phe→Ser) ,4 6 2位G→T(Glu→终止码 ) ,4 6 6位G→A(Gly→Glu) ,6 13位A→T(Lys→Ile) ,6 4 8位G→C(Gly→Arg) ,6 6 0位A→G(Arg→Gly)。结论 :食管癌高发区食管癌组织存在 polβ基因突变 ,且突变率较高 ;该酶基因突变可能与食管癌的发生。

噪声暴露引起大鼠听觉器官线粒体DNA缺失

目的 探讨线粒体DNA(mitochondrialDNA ,mtDNA)缺失与噪声性聋的关系。方法 3月龄大鼠分噪声暴露组和无暴露对照组 ,各 2 0只。噪声暴露组暴露于 1 0 8～ 1 1 0dBSPL的白噪声4h/d ,共 40d ;对照组不接触噪声。噪声暴露结束 2周后测试两组大鼠的听性脑干反应 (auditorybrainstemresponse ,ABR)阈值 ,聚合酶链反应 ( polymerasechainreaction ,PCR)检测其耳蜗、蜗核、颞叶脑组织和颞肌组织中是否存在mtDNA4834缺失 ,对存在的缺失进行定量分析 ;PCR产物进行克隆、测序。结果 噪声暴露组大鼠出现永久性阈移 ,其ABR平均阈值 ( x±s,下同 )为 ( 75 2 5± 6 1 7)dBSPL ( 4 0耳 ) ,对照组为 ( 34 75± 3 80 )dBSPL( 4 0耳 ) ,两组ABR阈值的差异具有非常显著性意义 (P<0 0 1 )。噪声暴露组大鼠的耳蜗、蜗核、颞叶脑组织中mtDNA4834缺失发生率 ( 2 4 /40、1 6/2 0、1 8/2 0 )明显高于对照组 ,两组之间的差异具有非常显著性意义 (P <0 0 1 ) ;而与听觉无关的颞肌组织中mtDNA4834缺失发生率 ( 2 /2 0 )在两组中均很低 ,两组之间的差异无显著性 (P >0 0 5 ) ;噪声暴露组大鼠的耳蜗、蜗核、颞叶脑组织和颞肌中mtDNA4834 缺失占总mtDNA的平均百分率 ( x±s)分别为( 0 9988± 0 5 5 1 6)× 1 0 - 2 %、( 1

基因重组Taq DNA聚合酶的制备

目的制备重组Taq DNA聚合酶,为PCR提供试剂。方法用Taq DNA聚合酶基因的pTaq表达质粒转化E.coli菌株,异丙基硫代-β-D-半乳糖苷(IPTG)诱导12 h表达Taq DNA聚合酶,溶菌酶、NP40裂解细菌,硫酸铵沉淀、4℃透析,SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)和PCR扩增分析其纯度和活性。结果分离纯化制备的Taq酶,纯度、活性都可与同类产品相比,能有效扩增DNA片段。结论该方法制备可用于PCR的Taq酶具有快速简便的优点。

人食管癌组织中DNA聚合酶β基因突变特点分析

目的 :探讨人食管癌DNA聚合酶beta (polβ)基因突变的特点。 方法 :对 75例人食管癌组织及 4例正常对照组织中提取总RNA ,进行RT PCR ,对PCR产物克隆后以Sanger’s法测序。结果 :人食管癌标本的polβ基因突变率 36 % (2 7/ 75 )。突变形式包括 :①A :G转换 ,突变频率为 6 6 .7% (18/ 2 7) ,375位的A→G (Ile→Val)、4 6 6位G→A(Gly→Glu)、6 6 0位A→G (Arg→Gly)、6 70位A→G(Glu→Gly)、74 0位A→G (Lys未改变 ) ;②T :C转换 ,突变频率 18.5 % (5 / 2 7) ,4 5 4位T→C(Phe→Ser)、6 6 5位T→C (Gly未改变 ) ;③G :T颠换 ,突变频率 18.5 % (5 / 2 7) ,4 6 2位G→T (Glu→提前终止于 116aa) ;④A :T颠换 ,突变频率 18.5 % (5 / 2 7) ,6 13位A→T(Lys→Ile)、737位A→T(Pro未改变 ) ;⑤G :C颠换 ,突变频率 7.4 % (2 / 2 7) ,6 4 8位G→C(Gly→Arg) ;⑥ 177～ 2 34位的 5 8bp缺失 ,移码及提前终止 ,突变频率为 37% (10 / 2 7)。结论 :人食管癌组织 polβ基因突变具有以下特点 :①标本突变率达 36 %(2 7/ 75 ) ;②有以A :G转换和G :T颠换为热点等多种突变形式 ;③ 2种提前终止可产生 2种截短的polβ蛋白 ,1种具有 116氨基酸长度 ;另一种 5 8bp的缺失者仅有 2

人食管癌组织DNA聚合酶β基因表达水平及定位

目的 :探讨人食管癌组织中DNA聚合酶 β基因 (polβ)表达水平及定位。 方法 :取 17例食管癌患者的癌组织、癌旁组织及其距癌灶 4～ 5cm处的正常组织。每块组织分 2等份 ,其中 1份常规石蜡包埋切片进行原位杂交 ,另 1份提取总RNA进行RNA斑点印迹 ,并以TLC扫描数值。结果 :蓝紫色杂交信号颗粒定位于胞质。弱信号见于正常组织的上皮基底细胞 ;癌旁组织的增殖细胞信号增强 ;癌组织分化较高的癌巢信号较弱 ;浸润的癌细胞信号强。原位杂交信号积分值与TLC扫描数值在癌、癌旁及正常组织中依次降低 (P <0 .0 5或P <0 .0 0 1)分别为 :癌组织 (32 .1± 7.8)和 (35 .8± 8.7) ,癌旁组织 (2 2 .1± 5 .3)和 (2 8.1± 6 .8) ,正常组织 (11.2± 2 .4 )和 (11.2± 2 .7)。结论 :人食管癌组织polβ基因呈高表达 ,DNA聚合酶 β较高表达可能是癌变早期事件。

脑胶质瘤组织中DNA聚合酶β基因突变检测

目的:研究人脑胶质瘤组织中DNA聚合酶β基因(polβ)的突变情况。方法:应用RT-PCR及SSCP检测22例脑胶质瘤、4例脑膜瘤、3例垂体瘤及1例肺部转移性鳞癌标本中polβ的表达,利用DNASIS、OMIGA软件及Chou&Fasman算法对扩增产物进行序列分析及蛋白质二、三级结构分析。结果:脑胶质瘤组织中DNApolβ突变率为6/22,共8个突变位点,2例发生504位A→G(131位Lys→Glu)、748位A→G(212位His→Arg)突变,2者蛋白质二级结构亦明显改变;598位T→C(162位Val→Ala)突变2例,但2者蛋白质二级结构无明显改变;2例Ⅲ级星形细胞瘤分别有2个和3个突变位点,但其各有1个相应的氨基酸未发生变异。Ⅱ级以下脑胶质瘤及脑膜瘤、垂体瘤等良性脑肿瘤组织均未发现DNApolβ基因突变。1例肺癌脑部转移性鳞状细胞癌DNApolβ基因出现5个突变位点,737位A→C(208位Pro未变异)、744位T→G(211位Lue→Val)、830位C→G(239位Cys→Trp)、866位A→C(251位Pro未变异)、870位A→C(253位Arg未变异),但蛋白质二级结构未改变。蛋白质三维结构图显示脑胶质瘤组织中6个氨基酸变异位点中,5个位于掌部,1个位于拇指部。结论:脑胶质瘤细胞中存在DNApolβ基因突变,且这些突变位点均为DNApolβ基因(尤其是掌部)活化结构域。提示脑胶质瘤的发生和发展可能与DNApolβ基因突变有关。

猪恶性高温综合征（MHS）基因群体检测及部分片段DNA序列研究

本研究主要包括：（１）建立了猪ＭＨＳ基因检测的ＰＣＲ－ＲＦＬＰ方法。该方法具有准确、快速和无侵害的特点；（２）利用猪ＭＨＳ基因的ＰＣＲ－ＲＦＬＰ方法对中国现有猪种２０个群体的ＭＨＳ基因座位的基因和基因型频率进行了检测。结果表明，属于中国的本地品种五指山猪、香猪，引进品种约克夏猪，均不含有ＭＨＳ基因；在中国本地品种二花脸猪和民猪中，发现存在ＭＨＳ基因，且民猪的频率较高（０．１５６２）；培育品种北京花猪，引进品种丹系长白猪和杜洛克猪，均有ＭＨＳ基因；引进品种皮特兰猪、比系长白猪，ＭＨＳ基因频率最高，分别为０．９５２０和０．９４３２；（３）猪ＲＹＲ１／ＣＲＣ基因部分ＤＮＡ序列品种间比较，ＭＨＳＮＮ香猪和二花脸猪的１８４３位为“Ｃ”，而ＭＨＳｎｎ为“Ｔ”；

河豚鱼16S rRNA基因部分DNA序列分析及应用

应用16S rRNA基因聚合酶链式反应（polymerase chain reaction,PCR）扩增通用引物,对3属13种福建省搜集的河豚鱼样品与9个未知物种的河豚鱼样品的16S rRNA基因序列中的部分片段进行PCR扩增与脱氧核糖核酸（deoxyribonucleic acid,DNA）碱基序列测定,各物种序列长度在611~614 bp之间。应用DNAMAN V6软件进行样品间DNA序列同源性比对分析,建立样品间系统关系同源树。供试13个样品被划分为4个类群组,群间的同源率为87%,群内同源率为94%~100%。根据序列同源性分析结果,9个未知种名的样品被归类到3个类群组中,推测9个未知种名的样品为东方鲀属或腹刺鲀属。探讨了16S rRNA基因部分DNA序列测试及同源性分析技术在河豚鱼种属鉴别中应用的可能性。

8-Br-cAMP和槲皮素对Eca-109细胞DNApolβ基因及相关基因表达的影响

目的 :探讨 8 Br cAMP及槲皮素等分化诱导剂对Eca 10 9细胞DNApolβ基因及相关基因表达的影响。 方法 :将培养的Eca 10 9细胞分为 3组 :①加 8 Br cAMP组 (Br组 ) ;②加槲皮素组 (Q组 ) ;③不加任何药物对照组 (C组 )。同时培养 4 8h ,将野生型DNApolβ的cDNA ,EGFRcDNA ,野生型 (wt)p5 3cDNA及c myccDNA分别制备了生物素 /地高辛标记的探针进行原位杂交和RNA斑点印迹阵列。另进行POLB ,XRCC1,VEGF及PCNA的免疫组化染色及免疫斑点印迹阵列。结果 :Br组和Q组的DNApolβ ,EGFR ,c myc基因表达下调而wtp5 3基因表达上调。POLB ,XRCC1,PCNA及VEGF免疫斑点印迹减弱。 8 Br cAMP及槲皮素显著下调Eca 10 9细胞的DNApolβ基因表达及相关癌基因表达 ,同时上调抑癌基因的表达。作为POLB的异二聚体XRCC1及恶性细胞生物标志的PCNA及VEGF表达下调。结论 :分化诱导剂下调Eca 10 9细胞DNApolβ基因表达 ,提示Eca 10 9细胞的polβ基因是高表达的 ;功能调整后的polβ通过相关基因表达的改变尤其是wtp5

基于双重PCR技术的鹿茸及其伪品DNA指纹特征和鉴定

目的:分析鹿茸线粒体细胞色素b(Cytb)和细胞色素C氧化酶亚基Ⅰ(COⅠ)基因特异性,建立双重PCR技术鉴别鹿茸真伪的分子指纹特征。方法:利用碱变性法提取梅花鹿茸、马鹿茸、驯鹿茸和新西兰鹿茸的基因组DNA,应用引物设计软件Premier 5.0针对Cytb和COⅠ分别设计特异性引物(分别为Cytb 1、2和COⅠ1、2、3),采用单一及双重引物分别进行PCR扩增,筛选特异性强的引物,确定最佳PCR反应条件。结果:采用碱变性法提取的鹿茸基因组DNA片段长度为23 000bp,DNA纯度即A(260)/A(280)为1.80±0.02;应用单一引物进行PCR扩增无法鉴定鹿茸的真伪,而引物Cytb 1和COⅠ1组合后,解链温度为58℃时,梅花鹿茸(吉林、安徽)、马鹿茸均能扩增出395和525bp大小的2个片段,而驯鹿茸和新西兰鹿茸均未能扩增出相应片段;采用该提取方法及最优化的PCR反应条件,对市售样品进行检测,检测结果与实际情况完全一致。结论:双重PCR技术可从分子水平鉴别鹿茸的真伪,该方法特异性高、实用性强,且简便快捷,在鹿茸真伪鉴别方面具有较高的应用价值。

甲基硝基亚硝基胍诱发的遗传不稳定细胞DNA聚合酶βmRNA表达水平研究

目的和方法：本实验室曾报道，低浓度０－２ μｍｏｌＬ 烷化剂甲基硝基亚硝基胍（ Ｎ－ ｍｅｔｈｙｌ－ Ｎ′－ ｎｉｔｒｏ － Ｎ－ｎｉｔｒｏｓｏｇｕａｎｉｄｉｎｅ ， ＭＮＮＧ） 可以诱导哺乳类细胞遗传不稳定状态。为明确其发生机制，本文利用定量ＲＴ－ ＰＣＲ 方法，研究了该低浓度ＭＮＮＧ 对人ＨｅＬａ 及猴肾ｖｅｒｏ 细胞ＤＮＡ 聚合酶β（ｐｏｌ β） ｍ ＲＮＡ 表达水平的影响。结果：经０－２ μｍｏｌＬ ＭＮＮＧ２ ．５ ｈ 处理后，ＨｅＬａ 细胞ｐｏｌ βｍ ＲＮＡ 水平在６ ～２４ ｈ 内升高约１ 倍；而ｖｅｒｏ 细胞ｐｏｌ βｍ ＲＮＡ 水平在１２ ～３０ ｈ 内亦升高１倍左右。结论：提示ｐｏｌ βｍＲＮＡ 水平改变可能参与ＭＮＮＧ

利用套叠PCR和高保真DNA聚合酶进行基因多位点突变的研究

利用套叠PCR和高保真DNA聚合酶对人工合成的牛口蹄疫病毒VPI基因(FMDV-VPl,Foot-Mouth Disease Virus-VPl)的5个突变位点进行修复,修复的成功率为100％。