Identification of differentially expressed mRNA species by an improved display technique (DDRT-PCR).

We have significantly improved a method originally developed by Liang and Pardee [Science 257 (1992) 967-971] to display a broad spectrum of expressed genes and to detect differences in expression between different cell types. We have analysed various aspects of the technique and have modified it for both, the application to fast and efficient identification of genes and the use with automatic analysis systems. Based on the mathematical background we have devised the appropriate number of optimal PCR primers. We have also introduced nondenaturating gels for separating double stranded fragments as single bands. By applying the method to regenerating mouse liver, we have identified, out of a total of 38,000 bands, about 70 fragments where the expression of the corresponding genes seems to be differentially regulated at different time points. Application of the method to an automatic DNA sequencer was successfully done. Thus, we have confirmed the usefulness and increased the power of the RNA display technique, which we named differential display reverse transcription PCR (DDRT-PCR), and have extended the range of its application.