Comparative method for detection of RNA-PCR-amplified signals.

During the development of a micro-method for the quantitative analysis of gene expression, we observed that the sensitivity for detection of PCR-amplified product was higher when silver staining was used, compared with either ethidium bromide staining (as reported previously) or Southern hybridization with 32P-labeled oligonucleotide probe. This observation may have an important impact on the analysis of RNA-PCR-amplified signal for the quantitation of mRNA expression, simply by densitometric scanning of silver-stained polyacrylamide gel. We believe that this is the first report to show such a comparison, demonstrating the greater sensitivity of silver staining compared with either ethidium bromide staining or Southern hybridization utilizing an oligonucleotide probe prepared by 3'-end labeling with 32P-dATP.