sentence: Using Northern blot analyses , we demonstrated that the PSE method can be also used to extract the pre-rRNAs associated with the late-intermediate ( 18S-E , 7S ; Fig. 1c ) and the early ( U3 small nucleolar RNA ( snoRNA ) , 30S , 26S , 21S , 32S , 12S ; Fig. 1c ) preribosomes in the expected SN1-SN2-SN3 and SN3 extracts , respectively ( Fig. 1d , lanes 4 – 6 ) .