[Transcription, in frog oocytes and transgenic mice, of recombinant plasmids with long terminal repeats of retrovirus proviruses].

RNA-DNA hybridization was used to study the transcription efficiency of the genes controlled by the long terminal repeats (LTR) from two different retroviral proviruses (exogenous provirus of the chicken Rous sarcoma virus and endogenous xenotropic provirus of the mouse). The oocyte nuclei of Xenopus laevis and the liver of transgenic mice were used as the transcription systems. The transcription efficiency of genes with the above mentioned promoters was shown to be roughly the same for both systems. Thus, the LTR of two proviruses of different origin possess the promoters of comparable strength and do not show any marked tissue or species specificity.