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QUANTITATIVE MONITORING OF GENE EXPRESSION PATTERNS WITH A COMPLEMENTARY DNA MICROARRAY AND WITH SERIAL ANALYSIS OF GENE EXPRESSION (SAGE)
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Specific patterns of gene expression occur during embryogenesis, development and during normal physiological responses in tissues and cells. The large number of databases developed for human genome will provide the unique opportunity to take a glimpse as how the intricate machinery of cells are driven by genes. Schena et al, describe a quantitative method for monitoring gene expression. Differential gene expression was demonstrated by a simultaneous two color hybridization scheme. Fluorescent DNA probes were prepared from two mRNA sources with the use of reverse transcriptase in the presence of fluorescein and lissamine-labeled nucleotide analogs. One set of probe was from control and the other from the tissue where differential gene expression was examined. The two probes were mixed in equal proportions and allowed to hybridize to microarrays consisting of a series of known cDNAs deposited on glass slides. After hybridization, the pattern of fluorescence was examined by separately scanning the fluorescence emitted from excited fluorescein and lissamine. This method allowed identification of genes that were expressed in given cells. This method should yield itself to automation for identification of genes that are differentially expressed in cells and tissues. A separate method called, serial analysis of gene expression (SAGE) was described by Velculescu et al in the Oct 1995 issue of Science. In this method, short sequence tags were isolated from the tissue, concatenated and cloned. The sequence of the clones allowed development of a profile for the gene expression. Qunatitative data regarding the prevalence of a expressed gene was derived from the frequency that a given sequence was found. Furthermore, new transcripts which corresponded to novel tags could be identified. Therefore, SAGE should allow defining quantitative assessment of gene expression in tissues under normal and abnormal conditions.
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QUANTITATIVE MONITORING OF GENE EXPRESSION PATTERNS WITH A COMPLEMENTARY DNA MICROARRAY AND WITH SERIAL ANALYSIS OF GENE EXPRESSION (SAGE)
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