The transcription of 5 S DNA injected into Xenopus oocytes

Abstract

The injection of purified 5 S DNA, of chromosomal or recombinant DNA origin, into Xenopus oocyte nuclei has been used to give further information about the transcription of these genes and about the transcriptional properties of oocytes. The transcription of injected 5 S DNA and SV40 DNA is sensitive to the concentrations of α-amanitin expected if it is dependent on RNA polymerase types III and II, respectively. Large amounts of injected 5 S DNA do not reduce the transcription of injected SV40 DNA or of endogenous rRNA synthesis in oocyte nuclei. Transcripts from injected 5 S DNA can be seen as little as 10 min after adding label; they are accurate transcripts from the correct strand and are of the normal size. 5 S DNA-injected oocytes can synthesize as much as 500 times more 5 S RNA than uninjected controls. At low doses, injected 5 S DNA is transcribed at about 20% of the efficiency of the oocytes' own 5 S genes. 5 S DNA is assembled into a nucleoprotein complex.