DETECTION OF MESSENGER-RNA AND LOW-ABUNDANCE HETERONUCLEAR RNA WITH SINGLE-STRANDED-DNA PROBES PRODUCED BY AMPLIFIED PRIMER EXTENSION LABELING

We describe a procedure for detection of low-abundance cellular RNAs b y in situ hybridization histochemistry, using single-stranded DNA prob es produced by amplified primer extension labeling with Tag polymerase . We have used this approach to detect a number of high- and low-abund ance RNA species and have found it to be a simple and reproducible met hod of obtaining sensitive probes for in situ hybridization studies. F or example, DNA probes generated by amplified primer extension labelin g can detect low-abundance heteronuclear RNAs in individual neurons. S ince this procedure does not involve recombinant DNA technology or mic robiological facilities, it should prove useful to a wide variety of i nvestigators studying the regulation of gene expression at the cellula r level.