DNA microarray

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Related to CDNA microarray: Oligonucleotide microarray

DNA microarray

An orderly arrangement of DNA sequences on a small solid support, usually a membrane or glass slide, used to quickly survey the simultaneous expression of many genes. Also called DNA chip.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
An array of DNA oligonucleotides synthesised in situ by photomasking on a semiconductor chip
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

DNA mic·ro·ar·ray

A technique used to identify the entire gene expression of bacterial cells. Microscopic spots of DNA are placed on a solid support in an array, and unknown samples fluorescently labeled are hybridized to the DNA on the array. A scanner is used to identify hybrids.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

DNA microarray

A collection of tens of thousands of DNA single-strand molecular probes capable of detecting specific genes or measuring gene expression in a sample of tissue. A gene is expressed when it is transcribed into messenger RNA (mRNA) and forms a protein. Currently, DNA microarrays are mainly used as research tools but they have great potential as diagnostic devices and as a reliable means of predicting a patients' susceptibility to various diseases.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005

DNA microarray

an orderly, low density arrangement of DNA samples, for example cDNA (see COPY DNA), immobilized as spots on a matrix. DNA microarrays can be fabricated by robotic spotting of single-stranded DNA PROBE molecules, on to the surface of a microscope slide, such that DNA of known identity is immobilized at precisely defined locations. A single slide may contain information for thousands of genes.

A typical DNA microarray/chip experiment involves matching known (probe) and unknown (target) nucleic acid samples on the basis of COMPLEMENTARY BASE PAIRING through HYBRIDIZATION, and automating the process of identifying the unknowns.

The target single-stranded nucleic acid sample, DNA or RNA, whose identity/ abundance is being determined, is labelled (see LABEL for example using a fluorescent dye, and incubated with the microarray/chip so that hybridization can occur between probe and target. Any unhybridized, free nucleic acid is washed away and HYBRID molecules detected by scanning and locating the positions of the fluorescent label. Abundance depends on the amount of fluorescence, whilst the position of fluorescence identifies the sample.

[Note: the definitions for the terms ‘probe’ and ‘target’ as used here differ from those used in classical hybridization. Here, the probe is immobilized and unlabelled, whilst the target is free and labelled.]

A problem with the use of microarrays is the potential for intra-strand BASE PAIRING in nucleic acid molecules, which could block probe-target interactions and hybrid formation. The use of PNA probes may circumvent this, since PNA:DNA hybrids can form under conditions that inhibit intra-strand base pairing in single-stranded DNA.

Microarrays/chips allow a large number of hybridization experiments to be carried out simultaneously in a single assay, so that thousands of GENES could be analysed in parallel. The technology can be used for a number of purposes including

  1. identification of genes;
  2. determination of the level of GENE/GENOME EXPRESSION in, for example, normal cells or tissues, diseased states, cell cycle analysis, and response to environmental stimuli;
  3. Detection of MUTATIONS and POLYMORPHISMS. For gene expression studies mRNA or cDNA is prepared and used to hybridize to specific probes. Hybrids identify the expressed genes.

Applications of the technology include drug discovery and development, human and agricultural diagnostics (see DIAGNOSIS), analysis of food and GMOs, SNP identification, and screening for TOXINS (see TOXICOGENOMICS).

DNA microarrays/chips are important tools in functional GENOMICS.

The terms ‘DNA microarray’ and ‘DNA chip’ are often used interchangeably although there is a technical difference. Other terminologies include biochip, gene chip, gene array

Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
Yan, "Searching for coexpressed genes in three-color cDNA microarray data using a probabilistic model-based hough transform," IEEE/ACM Transactions on Computational Biology and Bioinformatics, vol.
cDNA microarrays (23) revolutionized the analysis of the transcriptional response, saving materials and reducing costs to enable the high-throughput characterization of hundreds of genes in parallel.
Szallasi, "Redefinition of Affymetrix probe sets by sequence overlap with cDNA microarray probes reduces crossplatform inconsistencies in cancer-associated gene expression measurements," BMC Bioinformatics, vol.6,article107,2005.
To get more insight into the mechanism of apigenin action, we performed genome-wide expression profiling of apigenin-treated Huh7 cells using cDNA microarrays (Agilent Whole Human Genome Oligo Microarray) that contain 41,000 genes.
The authors of this proposed method (20) concluded that the new method for gridding, segmentation, and estimation to cDNA microarray images provided better segmentation results in spot shapes as well as intensity estimation than Spot and spot Segmentation R language software.
The algorithms of spot classification and segmentation have been evaluated on various cDNA microarray images.
(14,18) This study combined the use of cDNA microarray technology and EAE, to identify gene transcripts that are more abundant in either disease states, but not in normal white matter or normal mouse brains.
The potentially central role of synaptic vesicle function in the development of AD has been further supported by the findings of Yao and colleagues (2003), who also conducted cDNA microarray analyses of brain tissue from AD patients.
cDNA microarray slide preparation and microarray analysis for the selected SSH cDNA clones was carried out in the Genomics Core Facility, University of Alabama at Birmingham, AL, USA.