smear Northern

[kankaku]

I believe I am not poor at Northern.  However, this time, I have trouble with 
obtaining signals for my rare transcript.  I tried various things, using
DNA probes, 
riboprobes, partial digestion, total RNA, polyA RNA, formaldhyde, glyoxal, 
various membranes, various hybridization solutions.  But, nothing improved 
the smear, but specific band.  Of course, my RNA sample looks very intact 
because signals for other transcripts as well as rRNA are beautiful. I quess 
the turn-over of the rare mRNA is very rapid.  I need to know the size of the 
mRNA.  So, other methods such as RPA are not useful for my purpose.  
I would appreciate it if someone would suggest how to obtain a good 
Northern signal for such a transcript.