DNA microarray

Abstract

DNA microarray is a technology that has revolutionized the functional genomics with a wide array of applications. It is an arrangement of a large number of known genes or corresponding cDNA probes, for a given physiological condition of any living being; that are placed precisely as dots on a glass slide or chip or coated on beads. It works on the principle of Southern hybridization wherein DNA is hybridized with DNA to confirm the expression of a gene. The only difference is, in microarrays probes are placed on solid surface and testDNAis in the hybridization solution, which is just opposite to Southern hybridization where DNA to be diagnosed is placed on nylon or nitrocellulose membrane and probe is in the hybridization solution. DNA microarray helps in screening of thousands of genes in one go to understand their expression in a given physiological condition, when hybridized with the test DNA. During hybridization, fluorescent dyes attached to probes produce emissions of specific color based on complete partial and no binding of DNA to the probes. After hybridization these emissions can be observed and recorded under a confocal laser microscope and further analyzed with the help of image analysis software to understand set of genes up or down regulated in the test DNA and to determine fluorescence intensities that allow the quantitative comparison between the two test DNAs for all genes on the array. This technique is useful in gene expression profiling, comparative genomic hybridization, checking GeneID, SNP detection, alternative splicing detection, fusion gene detection and genome tilling to empirically detect expression of transcripts, or alternative splice forms. It has been widely applied in studies related to cancer biology, microbiology, plant science, environmental science, etc.