Subtractive hybridization: A technique for the isolation of differentially expressed genes

The technique of subtractive hybridization has been successfully used to isolate and identify rare and/or differentially expressed genes in specific tissues or under specific conditions. This technique allows for the isolation and subsequent identification of cDNA clones that can represent as little as 0.01% of the original mRNA population. Alterations in gene expression are invariably closely related to the primary initiation of changes in normal embryonic development, if not the primary event itself. Similarly, manifestations of cellular/tissue toxicity will be reflected in changes in gene expression of the target sites. The ability to isolate changing gene species, and subsequently to characterize the protein(s) they form, means that subtractive hybridization is potentially a powerful tool for characterizing both normal and abnormal conditions in animals and plants. This report reviews some of the recent applications of this technique, details a protocol we have used successfully in studies on abnormal mammalian development, and briefly describes our results.