Differential Display of Expressed mRNAs

Abstract

Biological responses to processes including stimulation with growth factors or cell differentiation depend on changes in the expression of the 50000–100000 genes that are encoded in the genomes of higher eukaryotes. Therefore, it is important that the technology used for monitoring changes in gene expression is able to detect quantitative and qualitative differences in the expression of all of these genes, although only a subset of perhaps 8000–15000 genes are expressed at any one time in a given cell type (Fields et al. 1994). The optimal technology should be able to detect even small differences in the expression of this subset. Previously, changes in gene expression have been examined on the mRNA/cDNA level by techniques such as subtractive or differential hybridization and on the protein level by 2-dimensional protein gel electrophoresis. However, there are limitations inherent to these techniques. The hybridization technique only allows two RNA/cDNA populations to be compared at a time and will only reveal major differences in gene expression; identical 2-dimensional protein gels are technically difficult to prepare and to interpret, and only the 2000–3000 most abundant proteins can be detected by autoradiography or silver staining (Celis et al. 1991).