RNA-RNA IN-SITU HYBRIDIZATION USING DIGOXIGENIN-LABELED PROBES - THE USE OF HIGH-MOLECULAR-WEIGHT POLYVINYL-ALCOHOL IN THE ALKALINE-PHOSPHATASE INDOXYL-NITROBLUE TETRAZOLIUM REACTION

A nonradioactive RNA-RNA in situ hybridization method using digoxigenin-labeled probes is described. The visualization of hybrids is done using the indoxyl-nitro blue tetrazolium alkaline phosphatase reaction. The addition of polyvinyl alcohols of high molecular weight (40-100 kDa) to the reaction medium enhances the alkaline phosphatase reaction and prevents diffusion of reaction intermediates, resulting in a 20-fold increase in sensitivity without increasing the background. Due to the more localized precipitation of the formazan, the site of hybridization can be determined more precisely. © 1993 Academic Press, Inc.