建立新型的常见腹泻相关病毒的多重检测方法

利用GenomeLab(tm)GeXP遗传分析系统建立一种同时检测A组轮状病毒、诺如病毒GI、GII型、札如病毒、肠道腺病毒、星状病毒、人博卡病毒II型7种常见腹泻相关病毒的方法。对反应条件进行优化后,非同日三次重复实验表明至少在104拷贝/μL水平可同时特异地检测出7种病毒,对Enterovirus71、Human Parechovirus、Picobir-navirusII阳性标本无交叉反应。本研究初步建立了一种高通量、快速的常见腹泻相关病毒的检测方法,为腹泻病原的分子诊断提供了新的方法。     

大数量序列的PCR保守引物设计实践

引物设计前的序列的全面检索,未注释序列的归类,经多序列比对求带有模糊碱基代码标识(IUPAC ambiguity codes)的共有序列,对设计高质量的引物至关重要,是引物设计过程的难点。目前,综合性核酸序列分析软件,单功能应用软件,在解决上述问题时均显不足。应用互联网提供的在线生物应用程序实践了一种多程序组合使用设计大数量序列的保守引物的方法,探讨了实现大数量序列的保守引物设计的一般流程。     

一种快速准确测定A群脑膜炎奈瑟菌活菌率的方法

目的研究"美蓝-(碱性)藏红O"双染色法用于快速准确测定A群脑膜炎奈瑟菌(group A Neisseria meningitidis,以下简称A群脑膜炎球菌)活菌率的可行性。方法制备A群脑膜炎球菌悬液,取菌悬液双染色法染色,用光学显微镜观察,计算活菌率。将菌悬液进行10倍系列稀释,各菌液分别用平板涂布法接种至10%羊血普通琼脂平皿,于CO2环境下、35~37℃培养12~20 h,计算菌悬液活菌率。比较两种方法测定8批A群脑膜炎球菌所测得的活菌率,并进行相关性和线性回归分析。结果 "美蓝-(碱性)藏红O"双染色法与平板涂布法所测得的活菌率结果差异无统计学意义(P>0.05);两种方法所测得的活菌率具有显著的直线回归关系(P<0.01,n=8),相关系数r=0.984,其回归方程为y=0.919x+1.661(R2=0.967)。结论 "美蓝-(碱性)藏红O"双染色法检测时间短、判定结果直观、操作简单、计数结果准确,可用于A群脑膜炎球菌活菌率的快速测定。     

Multiplexing RT-PCR for the detection of multiple miRNA species in small samples

MicroRNAs are short (approximately 22 nucleotides), non-coding RNAs that play critical roles in gene regulation and may be used as rapid precise diagnostic indicators of early stages of cancer. The small size of these RNAs makes detection of multiple microRNA species in very small samples problematic. Here we investigate the parameters associated with multiplexing RT-PCR to obtain relative abundance profiles of multiple microRNAs in small sample sizes down to the amount of RNA found in a single cell.     

A study of modified forms of the Lr19 translocation of common wheat

 Following the induction of allosyndetic pairing between the Thinopyrum-derived Lr19 translocation in ‘Indis’ wheat and homoeologous wheat chromatin, eight suspected recombinants for the Lr19 region were recovered. These selections were characterised for marker loci that were previously used to construct a physical map of the Lr19 segment. At the same time near-isogenic lines were developed for some of the selected segments and tested for seedling leaf-rust resistance in order to confirm the presence of Lr19. It appeared that three of the four white-endosperm selections do not possess Lr19 and only one, 88M22-149, is a true Lr19 recombinant. The resistance gene in the three non-Lr19 selections resides on chromosome 6B, appears to derive from ‘Indis’, and was selected unintentionally during backcrossing. The pedigree of ‘Indis’ is suspect and it is believed that the Lr19 translocation in ‘Indis’ is in reality the Th. ponticum-derived (T4) segment rather than being of Th. distichum origin as was believed earlier. The white-endosperm recombinant, 88M22-149, retained the complete Lr19 resistance and was apparently re-located to chromosome arm 7BL in a double-crossover event. 88M22-149 has lost the Sd1 gene and often shows strong self-elimination in translocation heterozygotes. This effect may result from additional gametocidal loci or from an altered chromosome structure following re-location of the segment. 88M22-149 in fact contains a duplicated region involving the Wsp-B1 locus. Three selections had partially white endosperms and expressed Lr19 and other Thinopyrum marker alleles. Polymorphisms for the available markers confirmed that the translocated segment in at least one of them had been shortened through recombination with chromosome arm 7DL. Further markers need to be studied in order to determine whether the translocation in the remaining two partially white recombinants had also undergone recombination with wheat. The eighth selection has yellow endosperm and appears to self-eliminate in certain translocation heterozygotes. No evidence of recombination could be found with the markers used. If the latter selections are in fact recombinants they may prove useful in attempts to unravel the complex segregation distortion mechanism. Received: 8 August 1996 / Accepted: 10 January 1997     

A self-probing primer PCR method for detection of very short DNA fragments

A novel self-probing primer method that based on the fluorescence resonance energy transfer principle is designed to detect DNA fragments of approximately 40 bp. Four self-probing primer reaction systems were developed to target a maize endogenous reference gene (HMG), a soybean endogenous reference gene (Lectin), a rapeseed endogenous reference gene (CruA) and an exogenous gene 5-enolpyruvylshikimate-3-phosphate synthase (ctp2-cp4epsps). These four primer systems were confirmed to have a high level of inter-species specificity and good intra-species stability. The limit of detection was estimated to be 10 copies of haploid genomes for all four assays. The validation results demonstrated that the self-probing primer methods are able to quantify the DNA amount in the different samples with good sensitivity and precision. When highly processed food products were assayed, the self-probing primer method produced better results than the TaqMan probe method. Overall, the self-probing primer method is suitable for qualitative and quantitative detection of very short DNA targets in samples of different sources.     

A simplified hydroethidine method for fast and accurate detection of superoxide production in isolated mitochondria

Because superoxide is involved in various physiological processes, many efforts have been made to improve its accurate quantification. We optimized and validated a superoxide-specific and -sensitive detection method. The protocol is based on fluorescence detection of the superoxide-specific hydroethidine (HE) oxidation product, 2-hydroxyethidium. We established a method for the quantification of superoxide production in isolated mitochondria without the need for acetone extraction and purification chromatography as described in previous studies.     

A single copy of SecYEG is sufficient for preprotein translocation

The heterotrimeric SecYEG complex comprises a protein‐conducting channel in the bacterial cytoplasmic membrane. SecYEG functions together with the motor protein SecA in preprotein translocation. Here, we have addressed the functional oligomeric state of SecYEG when actively engaged in preprotein translocation. We reconstituted functional SecYEG complexes labelled with fluorescent markers into giant unilamellar vesicles at a natively low density. Förster's resonance energy transfer and fluorescence (cross‐) correlation spectroscopy with single‐molecule sensitivity allowed for independent observations of the SecYEG and preprotein dynamics, as well as complex formation. In the presence of ATP and SecA up to 80% of the SecYEG complexes were loaded with a preprotein translocation intermediate. Neither the interaction with SecA nor preprotein translocation resulted in the formation of SecYEG oligomers, whereas such oligomers can be detected when enforced by crosslinking. These data imply that the SecYEG monomer is sufficient to form a functional translocon in the lipid membrane.     

A method for early detection of T-DNA transfer

A mannopine synthase—β-glucuronidase gene fusion,mas-uidA, was used to detect T-DNA transfer 48 hours afterA. tumefaciens infection of radish root disks. A detailed procedure for infection, tissue preparation and GUS histochemistry is given. A CaMV 35S promoter was shown to be unsuitable as it was highly expressed in the bacteria. A distinct pattern of GUS activity was found in radish roots infected with themas-uidA fusion indicating a specificity of expression in the metabolically active cambium and phloem parenchyma cells. This assay is useful for studying T-DNA transfer and host range differences amongA. tumefaciens strains.     

Quantitative analysis of topoisomerase IIalpha to rapidly evaluate cell proliferation in brain tumors

Immunohistochemical cell proliferation analyses have come into wide use for evaluation of tumor malignancy. Topoisomerase IIalpha (topo IIalpha), an essential nuclear enzyme, has been known to have cell cycle coupled expression. We here show the usefulness of quantitative analysis of topo IIalpha mRNA to rapidly evaluate cell proliferation in brain tumors. A protocol to quantify topo IIalpha mRNA was developed with a real-time RT-PCR. It took only 3 h to quantify from a specimen. A total of 28 brain tumors were analyzed, and the level of topo IIalpha mRNA was significantly correlated with its immuno-staining index (p<0.0001, r=0.9077). Furthermore, it sharply detected that topo IIalpha mRNA decreased in growth-inhibited glioma cell. These results support that topo IIalpha mRNA may be a good and rapid indicator to evaluate cell proliferate potential in brain tumors.     

A facile reporter system for the experimental identification of twin-arginine translocation (Tat) signal peptides from all kingdoms of life

We have developed a reporter protein system for the experimental verification of twin-arginine signal peptides. This reporter system is based on the Streptomyces coelicolor agarase protein, which is secreted into the growth medium by the twin-arginine translocation (Tat) pathway and whose extracellular activity can be assayed colorimetrically in a semiquantitative manner. Replacement of the native agarase signal peptide with previously characterized twin-arginine signal peptides from other Gram-positive and Gram-negative bacteria resulted in efficient Tat-dependent export of agarase. Candidate twin-arginine signal peptides from archaeal proteins as well as plant thylakoid-targeting sequences were also demonstrated to mediate agarase translocation. A naturally occurring variant signal peptide with an arginine-glutamine motif instead of the consensus di-arginine was additionally recognized as a Tat-targeting sequence by Streptomyces. Application of the agarase assay to previously uncharacterized candidate Tat signal peptides from Bacillus subtilis identified two further probable Tat substrates in this organism. This is the first versatile reporter system for Tat signal peptide identification.     

A familial complex chromosome translocation resulting in duplication of 6p25

We report on a girl with psychomotor retardation, severe speech developmental delay and mild dysmorphic features. Molecular cytogenetic analysis showed that the patient was carrier of an insertion (6)(p22.5-->22.4) in chromosome 12. Analysis of the chromosomes of the mother revealed the presence of a complex chromosomal rearrangement. In addition to the insertion (6)(p22.5-->22.4) in chromosome 12 and a pericentric inversion in chromosome 12, the 6p subtelomeric region was absent in the mother. This is, to our knowledge, the smallest pure duplication of chromosome 6p as well as the smallest cryptic subtelomeric 6pter deletion thus far reported.     

A rapid method for the characterisation of transgene junctions

Presented here is a simple method that enables amplification of the DNA immediately surrounding the junction between an inserted tDNA and the host genome, without prior sequence information.     

A PCR primer-specific to Cylindrocarpon heteronema for detection of the pathogen in apple wood

Abstract An oligonucleotide primer (ChInt) was synthesised from the variable internally transcribed spacer (ITS) 1 region of ribosomal DNA (rDNA) of Cylindrocarpon heteronema . PCR with primers ChInt and ITS4 (from a conserved sequence of the rDNA) amplified a 470-bp fragment from several isolates of C. heteronema but not from various apple wood saprophytes. Amplification of this fragment was achieved from 1–2 pg of fungal DNA. These primers amplified a fragment of the same size from DNA extracted from cankered wood but only after impurities were removed from the DNA on a Qiagen tip-5 column. Southern hybridization analysis confirmed the 470-bp fragment from C. heteronema DNA and cankered wood to be identical.     

Numerical sensitivity modeling for the detection of skin tumors by using tetrapolar probe

The measurement of electrical impedance of skin using surface electrodes permits the assessment of changes in local properties of the skin and can be used in the detection of tumors. The sensitivity of this technique depends mainly on the geometry of the probe and the size of the tumor. In this article, the impedance method was used to estimate the sensitivity of a tetrapolar probe in detecting small regions of increased conductivity in a stratified model of human skin. The impedance method was used to model the potential distribution using fasorial analysis to solve the node equations of the equivalent circuit. Interpolation was applied to reduce discretization error. The skin was modeled as a three-layer structure with different conductivity and permittivity obtained from the literature. A tumor was modeled as a small volume with admittivity four times higher than the normal tissue. Sensitivity calculation was made as a function of electrode diameter and separation, tumor size, and excitation frequency. The simulations indicated that by inserting a one square millimeter tumor in the epidermis, the load impedance to the current source varies about 1% while the transfer impedance varied 8%. The sensitivity also increases nonlinearly with increasing tumor area and thickness. Additionally, it was found that the sensitivity of the transfer impedance has a maximum value when the electrodes are separated by 1.8 mm. The results show that transfer impedance measurements of the skin may detect small skin tumors with a reasonable sensitivity by using an appropriate tetrapolar probe.     

检测博尔纳病病毒RNA的RACE技术的建立

目的建立检测博尔纳病病毒(BDV)RNA的3′RACE(rapid amplification of cDNA ends)方法。方法根据已知的BDV p40基因序列设计上游引物sp1;提取BDV(H1766株)持续感染OL细胞的总RNA,用引物sp1和oligo dT进行3′RACE扩增,将PCR产物克隆到pGEM-T载体并转化到大肠埃希菌中,制备阳性菌落的目的质粒,进行序列测定和同源性比对;同时对检测BDV RNA的3′RACE方法的特异性和敏感性进行分析。结果建立了检测BDV RNA的3′RACE技术;所获得的BDV p40基因的3′末端扩增产物的核苷酸序列与已知BDV(H1766株)p40基因的核苷酸序列同源性为100%;本方法对BDV RNA(mRNA)具有特异性,但对BDV p40基因重组质粒无扩增结果;并且可以检测到0.04 ng以上含量的BDV感染细胞的总RNA。结论检测BDV RNA的3′RACE技术可以排除实验室污染造成的BDV基因扩增的假阳性,并可用于进一步分析BDV基因序列的特点以及评价BDV相关基因的表达情况。     

麦蚜Cdc42基因的准确组织定位和定量分析方法研究

本文采用原位杂交方法,对Cdc42在麦长管蚜Sitobion avenae(Fabricius)不同组织分布进行定位,结果表明在滴加杂交液的组织切片被特异性的染成棕褐色,而阴性对照不着色;有、无翅蚜的头部和腹部均有特异性着色点,头部的着色点集中在两复眼之间,腹部的着色点几乎全集中在伪胚胎;有翅蚜的胸部几乎全部被着色,而无翅蚜的胸部几乎没有特异着色点。再运用实时荧光定量RT-PCR技术,进行了该基因的相对表达量测定,结果表明麦长管蚜Cdc42基因在不同组织及各虫期均能表达,若蚜期高于成蚜期,有翅蚜高于无翅蚜,且伪胚胎就有较高的转录水平。由此得知,基于原位杂交与实时荧光定量RT-PCR的技术相结合的方法,可有效进行麦蚜Cdc42基因的准确组织定位和定量分析,为Cdc42基因在麦蚜的翅型分化调控上的功能研究奠定了分子检测基础。