Looking to improve the quality of tools for discovering genomic regulatory regions, researchers at the National Institutes of Health combined Chromatin immunoprecipitation (ChIP) of hyper-acetylated histones, with serial analysis of gene expression (SAGE) technology. The process that they call genome-wide mapping technique (GMAT) could provide an alternative to ChIP-on-a-Chip techniques.1
Developers and others call it unbiased and quantitatively better. "They sequence everything they bring down, and then BLAST it against the database," says Axel Imhof at Munich University. ChIP on a chip is limited to what's on the microarray, mostly open-reading frames not bound by regulatory molecules, he adds. Microarray sequences are often the whole gene in one spot, providing no information on where in the gene it is modified, adds Dirk Schubeler, at the Friedrich Miescher Institute for Biomedical Research in Switzerland. "What we want is a microarray of very small pieces. But then it's becoming so many spots ...
