Synthesis of highly radioactively labelled RNA hybridization probes from synthetic single stranded DNA oligonucleotides

In the conventional methods of synthesizing highly radioactive RNA probes of suitable length (50-100 N) for genomic sequencing the subcloning of the corresponding DNA fragments is at least time consuming if not cumbersome and in some cases impossible. This is due mainly to the unavailability of appropriate restriction sites in the region of interest. However, it is nowadays possible to synthesize, within this size range, any desired single stranded oligonucleotide. The authors have developed a concise procedure for transcription of such oligonucleotides into highly radioactively labelled RNA without previous cloning.