Stable nuclear RNA returns to post-division nuclei following release to the cytoplasm during mitosis

When nuclei from 3H-RNA-containing amebae (A. proteus), chased for as many as 8 cell generations, are implanted into unlabeled enucleate cells, the nuclei retain 30% or more of the cellular 3H-RNA (or at least 15 times the cytoplasmic concentration of 3H-RNA). After such cells divide, the daughter nuclei retain approximately the same proportion of total cellular 3H-RNA—although all (or almost all) of the nuclear RNA is liberated to the cytoplasm during mitosis. Thus, we conclude that RNA stably associated with the interphase nucleus has a particular affinity for the nucleus despite the fact it is in the cytoplasm when the chromosomes are condensed and the nuclear envelope is not intact.