trimming polyA tails

[SCLAB]

There's an older paper - PNAS (1975) 72(8):2959-63 - dealing with this.

I believe others have used a specific oligo when the sequence near the
3' end of the transcript was known well enough to design one, and it
was supposedly cleaner after RNase H digestion than oligo dT.  May have 
even been in one of the Clontechniques, or Focus type publications a few 
years back, but not sure which.

--JM