passages.id: split_6_test_2933_passage
passages.type: progene_text
passages.text: Moreover , immunolocalization of RNA Pol I , but not of UBF , and the mRNA expression of PAF53 and UBF were significantly reduced or absent after culture with alpha - amanitin , indicating that RNA Pol I , PAF53 , and presumably , UBF are derived from de novo embryonic transcription .