Reverse transcription and direct amplification of cellular RNA transcripts by Taq polymerase

We report the ability of Taq polymerase to directly transcribe RNA templates in vitro. We have made use of this finding to develop a single-step protocol for amplification of RNA transcripts. The method was shown to require only subnanogram amounts of total cellular RNA as starting material. A microassay was developed in which RNA can be extracted from one drop of blood or 1000 cultured cells, and analyzed for the expression of a specific gene.