File Name: normalization of microarray data single labeled and dual labeled arrays .zip
Nowadays, microarray gene expression analysis is a widely used technology that scientists handle but whose final interpretation usually requires the participation of a specialist.
Systematic and gene-specific dye bias effects have been observed in dual-color experiments. In contrast to systematic effects which can be corrected by a normalization method, the gene-specific dye bias is not completely suppressed and may alter the conclusions about the differentially expressed genes. Methods: The gene-specific dye bias is taken into account using an analysis of variance model. We propose an index, named label bias index, to measure the gene-specific dye bias. It requires at least two self—self hybridization cDNA microarrays.
Normalization is a critical step in analysis of gene expression profiles. For dual-labeled arrays, global normalization assumes that the majority of the genes on the array are non-differentially expressed between the two channels and that the number of over-expressed genes approximately equals the number of under-expressed genes. These assumptions can be inappropriate for custom arrays or arrays in which the reference RNA is very different from the experimental samples. We propose a mixture model based normalization method that adaptively identifies non-differentially expressed genes and thereby substantially improves normalization for dual-labeled arrays in settings where the assumptions of global normalization are problematic. The new method is evaluated using both simulated and real data. The new normalization method is effective for general microarray platforms when samples with very different expression profile are co-hybridized and for custom arrays where the majority of genes are likely to be differentially expressed. Microarray technology provides simultaneous measurements of expression levels for thousands of genes.
Scientists use DNA microarrays to measure the expression levels of large numbers of genes simultaneously or to genotype multiple regions of a genome. Probe-target hybridization is usually detected and quantified by detection of fluorophore -, silver-, or chemiluminescence -labeled targets to determine relative abundance of nucleic acid sequences in the target. Also for identification of structural variations and measurement of gene expression. The core principle behind microarrays is hybridization between two DNA strands, the property of complementary nucleic acid sequences to specifically pair with each other by forming hydrogen bonds between complementary nucleotide base pairs. A high number of complementary base pairs in a nucleotide sequence means tighter non-covalent bonding between the two strands. After washing off non-specific bonding sequences, only strongly paired strands will remain hybridized. Fluorescently labeled target sequences that bind to a probe sequence generate a signal that depends on the hybridization conditions such as temperature , and washing after hybridization.
Keywords: loess/lowess; Normalization; RMA; Single-. labeled and Dual-labeled Arrays. Introduction. Microarray technology allows investigators to obtain.
Metrics details. The goal of this study was, first, to assess the quality of miRNA expression data based on microarray technologies and, second, to consolidate it by applying a novel normalization method. Indeed, because of significant differences in platform designs, miRNA raw data cannot be normalized blindly with standard methods developed for gene expression. This fundamental observation motivated the development of a novel multi-array normalization method based on controllable assumptions, which uses the spike-in control probes to adjust the measured intensities across arrays. They were used to apply several quality metrics based on the coefficient of variation and to test the novel spike-in controls based normalization method.
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. Corpus ID: Normalization of microarray data: single-labeled and dual-labeled arrays. Do and D. Choi Published Biology, Medicine Molecules and cells. DNA microarray is a powerful tool for high-throughput analysis of biological systems.
Dobbin, E. Kawasaki, D. Petersen, R. Motivation: Spot intensity serves as a proxy for gene expression in dual-label microarray experiments. Dye bias is defined as an intensity difference between samples labeled with different dyes attributable to the dyes instead of the gene expression in the samples. Dye bias that is not removed by array normalization can introduce bias into comparisons between samples of interest.
Keywords: loess/lowess; Normalization; RMA; Single- labeled and Dual-labeled Arrays. Introduction. Microarray technology allows investigators to obtain.
DNA microarray is a powerful tool for high-throughput analysis of biological systems. Various computational tools have been created to facilitate the analysis of the large volume of data produced in DNA microarray ex-periments. Normalization is a critical step for obtaining data that are reliable and usable for subsequent analysis such as identification of differentially expressed genes and clustering. A variety of normalization methods have been proposed over the past few years, but no methods are still perfect. Various assumptions are often taken in the process of normalization. Therefore, the knowledge of underlying assumption and principle of normaliza-tion would be helpful for the correct analysis of mi-croarray data.
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