PROFILING EXPRESSION PATTERNS AND ISOLATING DIFFERENTIALLY EXPRESSED GENES BY CDNA MICROARRAY SYSTEM WITH COLORIMETRY DETECTION

A high-density cDNA microarray with colorimetry detection system to si multaneously monitor the expression of many genes on nylon membrane is described and characterized. To quantify the expression of genes and to isolate differentially expressed genes, the southern hybridization process on filter membranes was employed. The levels of gene expressio n were represented by color intensities generated by colorimetric reac tions in place of hazardous radioisotopes or costly laser-induced fluo rescence detection. The gene expression patterns on nylon membranes we re digitized by devices such as an economical flatbed scanner or a dig ital camera. The quantitative information of gene expression was retri eved by image analysis software. Quantitative comparison of the northe rn dot-blotting method with the microarray system is described. Applic ations employing single-color detection as well as dual-color detectio n to isolate differentially expressed genes among thousands of genes a re demonstrated. (C) 1998 Academic Press