hybridization of labeled nascent rna to the cloned repeat unit and s1 nuclease protection analysis of putative precursors show that transcription initiates approximately 1.2 kb upstream of the 18s rrna and terminates after the last small rrna ( 140 ) at the 3 ' end of the 28s rrna region .
C0035668
rna
C0040649
transcription