PCR Entries



  • Hybridization signal amplification method
    • Hybridization signal amplification method Hybridization signal amplification method Hybridization signal amplification method Hybridization signal amplification method (HSAM), developed by Hamilton Thorne Bioscience, is an elegantly simple signal amplification method that takes advantage of some of the unique structural capabilities of nucleic acids. It is a companion to ramification amplification method (RAM). Conceptually, HSAM can be thought of as a variation on traditional probe network sign

  • Direct molecular analysis without amplification
    • Direct molecular analysis without amplification Direct molecular analysis without amplification Direct molecular analysis without amplification The Trilogy Platform (US Genomics) is founded on the belief that direct analysis of single biological molecules is the key to the next generation of revolutionary technologies. US Genomics is developing technologies that can directly analyze individual molecules of DNA, RNA and proteins, without PCR amplification. The process of direct analysis by the T

  • WAVE nucleic acid fragment analysis system
    • WAVE nucleic acid fragment analysis system WAVE nucleic acid fragment analysis system WAVE nucleic acid fragment analysis system Transgenomics' proprietary WAVE Nucleic Acid Fragment Analysis System has been designed and optimized to use the DNASep cartridge for separating (ds or ss) DNA. WAVE is also commonly known as DHPLC (denaturing high performance liquid chromatography). The system can easily resolve PCR products that have small differences in their lengths. The WAVE System is based on the

  • Real-Time PCR Systems
    • Real-Time PCR Systems Real-Time PCR Systems Real-Time PCR Systems Some of the limitations of end-point PCR have been addressed in real-time PCR systems, a number of which are now on the market. These systems offer many general technical advantages, including reduced probabilities of variability and contamination, as well as online monitoring and the lack of need for post reaction analyses. Further, some of these systems were developed with contemporary applications such as quantitative PCR, mult

  • Fluorescence and chemiluminescence
    • Fluorescence and chemiluminescence Fluorescence and chemiluminescence Fluorescence and chemiluminescence In earlier years scientists tagged samples ? whether nucleic acid, protein, cell, or tissue ? with radioactive labels, and captured images on film. Safety concerns, convenience, and sensitivity, spurred the development of alternative techniques, and today, researchers can choose from a range of options, including fluorescence and chemiluminescence, in addition to autoradiography. Fluorescence

  • 3 DNA dendrimer signal amplification
    • 3 DNA dendrimer signal amplification 3 DNA dendrimer signal amplification 3 DNA dendrimer signal amplification The name 'dendrimer', derived from the Greek word for 'tree', suggests the unusual structure of this highly branched molecule. As a class, dendrimers are complex, branched molecules built from interconnected natural or synthetic monomeric subunits. A 3DNA dendrimer is constructed from DNA monomers ­ as the name '3DNA' indicates. Each 3DNA monomer is composed of two DNA strands that shar

  • Introduction to biochip technology
    • Introduction to biochip technology Introduction to biochip technology Introduction to biochip technology Scientists and engineers are borrowing miniaturization, integration, and parallel-processing techniques from the computer industry to develop laboratory devices and procedures that will fit on a wafer or microchip. Biochip is a broad term indicating the use of microchip technology in molecular biology and can be defined as arrays of selected biomolecules immobilized on a surface. DNA microarr

  • Molecular beacons
    • Molecular beacons Molecular beacons Molecular beacons Molecular beacons were developed as an extension of the concept of fluorescently labeled oligonucleotides. The molecular beacon is a folded probe that gives no fluorescent signal in the folded position due to quenching of the label. Upon hybridization of the molecular beacon to the target sequence (amplicon RNA), the probe unfolds and the fluorescent label emits light. When the molecular beacon is away from its target sequence, the stem struc

  • Rolling circle amplification technology
    • Rolling circle amplification technology Rolling circle amplification technology Rolling circle amplification technology Rolling circle amplification technology (RCAT), a proprietary amplification process developed by Molecular Staging Inc, has significant advantages in terms of sensitivity, multiplexing, dynamic range and scalability. The steps of this procedure are: 1. A short DNA probe anneals to a target DNA of interest, such as the DNA of a pathogenic organism or a human gene containing a de

  • Nucleic acid sequence-based amplification
    • Nucleic acid sequence-based amplification Nucleic acid sequence-based amplification Nucleic acid sequence-based amplification Nucleic acid sequence-based amplification (NASBA) is the basis of the NucliSens system of Organon Teknika (now part of bioMerieux) and offers a simple and rapid alternative method for nucleic acid amplification. A description of the technology is available on the web site (http://www.nuclisens.com/). NucliSens represents a synergy of three key technologies ­ integrating i

  • primer design
    • primer design primer design Please cite this article as follows: PCR Encyclopedia (2005) 1: 101050-00 primer design PCR Encyclopedia (2005) 1: 101050-00 The DNA fragment to be amplified is determined by selecting primers. Primers are short, artificial DNA strands, usually 18-25 nucleotides, that match the beginning and end of the DNA fragment to be amplified. They anneal to the DNA template at these starting and ending points. The DNA-Polymerase then binds and begins the synthesis of the new DNA

  • Primers in the polymerase chain reaction.
    • Primers in the polymerase chain reaction. Home Primers. The DNA fragment to be amplified is determined by selecting primers. Primers are short, artificial DNA strands, usually 18-25 nucleotides, that match the beginning and end of the DNA fragment to be amplified. They anneal to the DNA template at these starting and ending points. The DNA-Polymerase then binds and begins the synthesis of the new DNA strand. The choice of the length of the primers and their melting temperature (Tm) depends on a

  • Signal mediated amplification of RNA technology
    • Signal mediated amplification of RNA technology Signal mediated amplification of RNA technology Signal mediated amplification of RNA technology Signal mediated amplification of RNA technology (SMART) has been developed by Cytocell. The assay consists of two oligonucleotide probes that hybridize to a specific target sequence and, only then, to each other forming a three-way junction. One probe (template for the RNA signal) contains a non-functional single-stranded T7 RNA polymerase promoter seque

  • pcr
    • pcr pcr Please cite this article as follows: PCR Encyclopedia (2005) 1: 101052-10 pcr PCR Encyclopedia (2005) 1: 101052-10 The DNA fragment to be amplified is determined by selecting primers. Primers are short, artificial DNA strands, usually 18-25 nucleotides, that match the beginning and end of the DNA fragment to be amplified. They anneal to the DNA template at these starting and ending points. The DNA-Polymerase then binds and begins the synthesis of the new DNA strand. The choice of the len

  • Detection of amplified DNA
    • Detection of amplified DNA Detection of amplified DNA Detection of amplified DNA The first detection methods used with PCR were radioactively labeled probes that identified specific amplified sequences. With improvements in specificity, it became possible to visualize amplified DNA of the predicted size directly by examining its fluorescence after staining. Probes have now been converted to nonisotopic colorimetric systems. In another approach, the probe is a 'reverse' component (bound to a memb

  • Transcription mediated amplification
    • Transcription mediated amplification Transcription mediated amplification Transcription mediated amplification Transcription mediated amplification (TMA) is an isothermal nucleic-acid-based method that can amplify RNA or DNA targets a billion-fold in less than one houršs time. This system is useful for detecting the presence of M. tuberculosis and C. trachomatis. Developed at Gen-Probe, TMA technology uses two primers and two enzymes: RNA polymerase and reverse transcriptase. One primer contains

  • Molecular labels
    • Molecular labels Molecular labels Molecular labels Many types of nucleic acids require a secondary detection technology, e.g. a label, because a nucleic acid does not have intrinsic properties that are useful for direct high-sensitivity detection. Reasons for ultrasensitive nucleic acid detection include analysis of genetic material from single cells and single copy gene detection. Molecular labels provide the means for detecting and evaluating most biological interactions, such as those involvi

  • Cycling probe technology
    • Cycling probe technology Cycling probe technology Cycling probe technology Cycling probe technology (CPT) was developed by ID Biomedical and licensed to Takara Biomedical Group. It involves the introduction and multiplication of probes that are specific for the organisms being sought. Each probe is a sandwich of two short DNA segments attached to the two ends of an RNA segment. The probe attaches to a single strand of target DNA. Then the RNA strand is cut into two by RNase H, a naturally occurr

  • Linear RNA amplification
    • Linear RNA amplification Linear RNA amplification Linear RNA amplification Incyte Corporation's Linear amplification technology is based on antisense RNA amplification and involves a series of enzymatic reactions resulting in T7-based linear amplification of RNA from small amounts of sample RNA. It can be applied to RNA obtained from small biopsies, mRNA-poor cells and tissues, primary cell culture and laser capture micro-dissection (LCM) samples. Unlike exponential amplification methods such as

  • Principle of PCR for Laboratory Diagnosis of Disease
    • Principle of PCR for Laboratory Diagnosis of Disease Principle of PCR for Laboratory Diagnosis of Disease Principle of PCR for Laboratory Diagnosis of Disease PCR is based on the enzymatic amplification of a fragment of DNA that is flanked by two 'primers', short oligonucleotides that hybridize to the opposite strands of the target sequence and then prime synthesis of the complementary DNA sequence by DNA polymerase (an enzyme). The chain reaction is a three-step process, denaturation, annealing

  • Rapid analysis of gene expression
    • Rapid analysis of gene expression Rapid analysis of gene expression Rapid analysis of gene expression Current techniques for analysis of gene expression either monitor one gene at a time, for example northern hybridization or RT-PCR methods, or are designed for the simultaneous analysis of thousands of genes, for example microarray hybridization or serial analysis of gene expression. To provide a flexible, intermediate scale alternative, a PCR-based method RAGE (rapid analysis of gene expression

  • Enzyme labels and detection by fluorescence
    • Enzyme labels and detection by fluorescence Enzyme labels and detection by fluorescence Enzyme labels and detection by fluorescence The basis of most nucleic acid assays is exploitation of the specificity of base recognition (e.g., adenine for thymine) and the high binding constant of resulting duplexes. Competitive and noncompetitive amperometric immunoassays have been developed with enzymes as labels. The sensitivity of assays can be improved by using an enzyme label such as acetate kinase, wh

  • Linked Linear Amplification
    • Linked Linear Amplification Linked Linear Amplification Linked Linear Amplification Linked Linear Amplification (LLA) is a new nucleic acid amplification method that uses multiple cycles of primer extension reactions. The presence of nonreplicable elements in LLA primers renders primer extension products unusable as templates for further amplification, leading to linear accumulation of products. Through the use of nested primers, linear reactions can be 'linked', providing total amplification yi

  • PCR in Molecular Diagnostics
    • PCR in Molecular Diagnostics PCR in Molecular Diagnostics PCR in Molecular Diagnostics The polymerase chain reaction (PCR) is a method of nucleic acid analysis for producing large amounts of a specific DNA fragment of a defined sequence and length from a small amount of a complex template. It can selectively amplify a single molecule of DNA or RNA several million-fold in a few hours. Use of this technology enables the detection and analysis of specific gene sequences in a patient's sample withou

  • Detection technologies for molecular labels
    • Detection technologies for molecular labels Detection technologies for molecular labels Detection technologies for molecular labels A vast array of different labels and assay strategies has been developed to meet the requirements of sensitivity, accuracy and convenience. Instruments for detection include: fluorescence and confocal microscopy, flow cytometry, laser scanning cytometry, fluorescence microplate analysis and biochips. The development of increasingly sensitive labels and detection equ

  • Is it a true positive?
    • Is it a true positive? Is it a true positive? Please cite this article as follows: PCR Encyclopedia (2005) 1: 092327-55 Is it a true positive? PCR Encyclopedia (2005) 1: 092327-55 Our county health department STD program receives thousands of positive chlamydia, gonorrhea and syphilis reports every year. Over the past 10 years we have noticed an unusual number of positive PCR chlamydia from several labs where the female is pregnant, denies any signs or symptoms & has only one partner. As per CDC

  • Target Selection for Diagnostic PCR
    • Target Selection for Diagnostic PCR Target Selection for Diagnostic PCR Target Selection for Diagnostic PCR Several strategies are available for selecting a genetic target to be amplified so as to detect an infectious disease organism. For example, genes that contain both conserved and variable sequence regions may be targeted. In such a case, specificity may be obtained either at the amplification (primer) or detection (probe) stage. The target may also consist of a virulent gene that is unique

  • Primers in the polymerase chain reaction.
    • Primers in the polymerase chain reaction. Home Primers in the polymerase chain reaction. Primers in the polymerase chain reaction. Primers in the polymerase chain reaction. Primers are short, artificial DNA strands of about 18 to 25 nucleotides that match the beginning and end of the DNA fragment to be amplified. The primers anneal to the single-stranded DNA template at these points. Once the primers bind, the DNA-Polymerase binds and begins the synthesis of the new DNA strand. Related Links The

  • Signal amplification
    • Signal amplification Signal amplification Signal amplification Signal amplification implies direct detection of nucleic acids without target amplification. Various technologies for signal amplification are available. Related Links The PCR Jump Station | Information and links on PCR | The PCR Gateway | The PCR Directory The PCR Encyclopedia


    Related Links The PCR Jump Station | Information and links on PCR | The PCR Gateway | The PCR Directory


    The PCR Encyclopedia