Analysis of relative gene expression data using real-time quantitative PCR and the 2(-Delta Delta C(T)) Method
The two most commonly used methods to analyze data from real-time, quantitative PCR experiments are absolute quantification and relative quantification. Absolute quantification determines the input copy number, usually by relating the PCR signal to a standard curve. Relative quantification relates the PCR signal of the target transcript in a treatment group to that of another sample such as an untreated control.
The 2(-Delta Delta C(T)) method is a convenient way to analyze the relative changes in gene expression from real-time quantitative PCR experiments. The purpose of this report is to present the derivation, assumptions, and applications of the 2(-Delta Delta C(T)) method. In addition, we present the derivation and applications of two variations of the 2(-Delta Delta C(T)) method that may be useful in the analysis of real-time, quantitative PCR data
A new mathematical model for relative quantification in real-time RT-PCR
Use of the real-time polymerase chain reaction (PCR) to amplify cDNA products reverse transcribed from mRNA is on the way to becoming a routine tool in molecular biology to study low abundance gene expression. Real-time PCR is easy to perform, provides the necessary accuracy and produces reliable as well as rapid quantification results. But accurate quantification of nucleic acids requires a reproducible methodology and an adequate mathematical model for data analysis. This study enters into the particular topics of the relative quantification in real-time RT-PCR of a target gene transcript in comparison to a reference gene transcript.
Therefore, a new mathematical model is presented. The relative expression ratio is calculated only from the real-time PCR efficiencies and the crossing point deviation of an unknown sample versus a control. This model needs no calibration curve. Control levels were included in the model to standardise each reaction run with respect to RNA integrity, sample loading and inter-PCR variations. High accuracy and reproducibility (<2.5% variation) were reached in LightCycler PCR using the established mathematical model
One-step inactivation of chromosomal genes in Escherichia coli K-12 using PCR products
We have developed a simple and highly efficient method to disrupt chromosomal genes in Escherichia coli in which PCR primers provide the homology to the targeted gene(s). In this procedure, recombination requires the phage lambda Red recombinase, which is synthesized under the control of an inducible promoter on an easily curable, low copy number plasmid. To demonstrate the utility of this approach, we generated PCR products by using primers with 36- to 50-nt extensions that are homologous to regions adjacent to the gene to be inactivated and template plasmids carrying antibiotic resistance genes that are flanked by FRT (FLP recognition target) sites. By using the respective PCR products, we made 13 different disruptions of chromosomal genes.
Mutants of the arcB, cyaA, lacZYA, ompR-envZ, phnR, pstB, pstCA, pstS, pstSCAB-phoU, recA, and torSTRCAD genes or operons were isolated as antibiotic-resistant colonies after the introduction into bacteria carrying a Red expression plasmid of synthetic (PCR-generated) DNA. The resistance genes were then eliminated by using a helper plasmid encoding the FLP recombinase which is also easily curable. This procedure should be widely useful, especially in genome analysis of E. coli and other bacteria because the procedure can be done in wild-type cells
Refinement of macromolecular structures by the maximum-likelihood method.
This paper reviews the mathematical basis of maximum likelihood. The likelihood function for macromolecular structures is extended to include prior phase information and experimental standard uncertainties. The assumption that different parts of a structure might have different errors is considered.
Description: Creative Biogene Monkeypox Virus Real Time PCR Kit is used for the detection of monkeypox Virus in serum or lesion exudate samples by using real time PCR systems. Monkeypox virus (MPV) is a double-stranded DNA, zoonotic virus and a species of the genus Orthopoxvirus in the family Poxviridae. It is one of the human orthopoxviruses that includes variola (VARV), cowpox (CPX), and vaccinia (VACV) viruses. The kit contains a specific ready-to-use system for the detection of the monkeypox Virus. Fluorescence is emitted and measured by the real time systems' optical unit during the PCR.
Description: Monkeypox virus is the virus that causes the disease monkeypox in both humans and animals. Monkeypox virus is an Orthopoxvirus, a genus of the family Poxviridae that contains other viral species that target mammals. The virus is mainly found in tropical rainforest regions of central and West Africa. The primary route of infection is thought to be contact with the infected animals or their bodily fluids. The genome is not segmented and contains a single molecule of linear double-stranded DNA, 185000 nucleotides long. The Monkeypox Virus real time PCR Kit contains a specific ready-to-use system for the detection of the Monkeypox Virusthrough polymerase chain reaction (PCR) in the real-time PCR system. The master contains reagents and enzymes for the specific amplification of the Monkeypox Virus DNA. Fluorescence is emitted and measured by the real time systems ́ optical unit during the PCR. The detection of amplified Monkeypox Virus DNA fragment is performed in fluorimeter channel 530nm with the fluorescent quencher BHQ1. DNA extraction buffer is available in the kit and serum or lesion exudate samples are used for the extraction of the DNA. In addition, the kit contains a system to identify possible PCR inhibition by measuring the 560nm fluorescence of the internal control (IC). An external positive control defined as 1×10^7 copies/ml is supplied which allow the determination of the gene load.
Description: Monkeypox virus is the virus that causes the disease monkeypox in both humans and animals. Monkeypox virus is an Orthopoxvirus, a genus of the family Poxviridae that contains other viral species that target mammals. The virus is mainly found in tropical rainforest regions of central and West Africa. The primary route of infection is thought to be contact with the infected animals or their bodily fluids.The genome is not segmented and contains a single molecule of linear double-stranded DNA, 185000 nucleotides long.The Monkeypox Virus real time PCR Kit contains a specific ready-to-use system for the detection of the Monkeypox Virusthrough polymerase chain reaction (PCR) in the real-time PCR system. The master contains reagents and enzymes for the specific amplification of theMonkeypox VirusDNA. Fluorescence is emitted and measured by the real time systems ́ optical unit during the PCR. The detection of amplified Monkeypox Virus DNA fragment is performed in fluorimeter channelFAM with the fluorescent quencher BHQ1. DNA extraction buffer is available in the kit and serum or lesion exudate samples are used for the extraction of the DNA. In addition, the kit contains a system to identify possible PCR inhibition by measuring the HEX/VIC/JOE fluorescence of the internal control (IC). An external positive control defined as 1×107copies/ml is supplied which allow the determination of the gene load.
Description: The Bioperfectus Monkeypox Virus Real Time PCR Kit is an in vitro diagnostic test, based on real-time PCR technology, for the detection of DNA from the Monkeypox virus. Specimens can be obtained from human serum, lesion exudate samples and scab. BSL-2 facilities with standard BSL-2 work practices may be used for the test of t he Monkeypox virus.
A method for estimating sigma(A) using ‘free’ reflections is described and its effects analysed. The derived equations have been implemented in the program REFMAC. This has been tested on several proteins at different stages of refinement (bacterial alpha-amylase, cytochrome c’, cross-linked insulin and oligopeptide binding protein). The results derived using the maximum-likelihood residual are consistently better than those obtained from least-squares refinement.
MicroRNAs: target recognition and regulatory functions.
MicroRNAs (miRNAs) are endogenous approximately 23 nt RNAs that play important gene-regulatory roles in animals and plants by pairing to the mRNAs of protein-coding genes to direct their posttranscriptional repression. This review outlines the current understanding of miRNA target recognition in animals and discusses the widespread impact of miRNAs on both the expression and evolution of protein-coding genes.
Cytoscape: a software environment for integrated models of biomolecular interaction networks.
Cytoscape is an open source software project for integrating biomolecular interaction networks with high-throughput expression data and other molecular states into a unified conceptual framework. Although applicable to any system of molecular components and interactions, Cytoscape is most powerful when used in conjunction with large databases of protein–protein, protein-DNA, and genetic interactions that are increasingly available for humans and model organisms. Cytoscape’s software Core provides basic functionality to layout and query the network; to visually integrate the network with expression profiles, phenotypes, and other molecular states; and to link the network to databases of functional annotations.
The Core is extensible through a straightforward plug-in architecture, allowing rapid development of additional computational analyses and features. Several case studies of Cytoscape plug-ins are surveyed, including a search for interaction pathways correlating with changes in gene expression, a study of protein complexes involved in cellular recovery to DNA damage, inference of a combined physical/functional interaction network for Halobacterium, and an interface to detailed stochastic/kinetic gene regulatory models.
Isolation of biologically active ribonucleic acid from sources enriched in ribonuclease.
Intact ribonucleic acid (RNA) has been prepared from tissues rich in ribonuclease such as the rat pancreas by efficient homogenization in a 4 M solution of the potent protein denaturant guanidinium thiocyanate plus 0.1 M 2-mercaptoethanol to break protein disulfide bonds. The RNA was isolated free of protein by ethanol precipitation or by sedimentation through cesium chloride. Rat pancreas RNA obtained by these means has been used as a source for the purification of alpha-amylase messenger ribonucleic acid.
MrBayes 3: Bayesian phylogenetic inference under mixed models.
MrBayes 3 performs Bayesian phylogenetic analysis combining information from different data partitions or subsets evolving under different stochastic evolutionary models. This allows the user to analyze heterogeneous data sets consisting of different data types-e.g. morphological, nucleotide, and protein-and to explore a wide variety of structured models mixing partition-unique and shared parameters. The program employs MPI to parallelize Metropolis coupling on Macintosh or UNIX clusters.
