Genomic microarray analysis

Abstract

Microarrays utilize classical hybridization techniques to measure the levels of expression of genomic sequences. Advances in microarray fabrication using robotic technology and bioinformatics, now means entire genomes can be interrogated with a high degree of sensitivity, specificity and throughput. To achieve this, RNA collected from samples is first transcribed into complimentary RNA (cRNA) that is subsequently fragmented and labeled with biotin. These fragments are allowed to hybridize with their complementary oligonucleotide sequence located in microscopic features on the array support media. Each of these features consists of hundreds of short oligonucleotide probes that match the target mRNA sequence. This results in an increase in abundance of biotinylated cRNA molecules on the feature to which a fluorescent dye is subsequently bound. The fluorescence levels can then be used to infer the relative abundance of specific mRNA sequences in the original sample. The microarray analysis of gene expression is thus a key weapon in the molecular biology arsenal that can open windows to the molecular processes manifested by the phenotypic differences observed between normal and diseased states.