Nucleotide sequence homologies in nuclear and cytoplasmic ribonucleic acid from rat liver and hepatomas.

Abstract

The RNA popoulations of rat liver and three rat hepatomas were compared by DNA‐RNA hybridization studies in the presence and absence of competing RNA. The hepatoma nuclei were found to lack hybridizable RNA species present in normal liver nuclei, while the latter appeared to contain all the hepatoma RNA species. In normal liver, the cytoplasmic RNA could compete with nuclear RNA only to the extent of 20–30 %. This indicates that a large number of nuclear RNA species are not transferred to the cytoplasm. In the case of the hepatomas nearly all the nuclear RNA species were detected in the cytoplasmic RNA preparations. A more extensive homology between nuclear and cytoplasmic RNA was also observed in regerenating liver. It is suggested that a selective mechanism governs the transfer of RNA species from the nucleus to the cytoplasm and that this mechanism is altered in the hepatomas.