difference between pre-miRNA and mature miRNA on Northern blot - (Apr/09/2008 )

How can I distinguish between mature miRNA and pre-miRNA on northern blot analysis if I just use 1 probe? Is there a method to separate RNA very precisely? So that you can see the difference between 1 nucleotide more or less?

The mature duplex and the hairpin will migrate at different rates across the gel. For an example see figure 2G of:
Kloosterman WP, Lagendijk AK, Ketting RF, Moulton JD, Plasterk RH. Targeted Inhibition of miRNA Maturation with Morpholinos Reveals a Role for miR-375 in Pancreatic Islet Development. PLoS Biol. 2007 Jul 24;5(8):e203 [Epub ahead of print]
http://biology.plosjournals.org/perlserv/?...al.pbio.0050203