RNA EXTRACTION

[O KANSAS]

I am trying to separate total RNA from some mouse tissues
such as liver and kidney.  I have used TriReagent (Sigma) and 
acid-guanidine isothiocyanate protocols.  I have got nice looking 18S
and 28S bands and above 1.8 A260/280 ratio. But the problem is
abnormally stong 5S/7S rRNA-like band in the gel (Mops and
formaldehyde).  Normally, 5S/7S rRNA bands are much weaker than 18S or 28S
rRNAs.  I thought this is DNA contaminant or salt at first, but the strong
band (and 18s/28S) could be removed after RNase treatment.  I would like to
remove this band for my next procedure (RNase protection).

Any suggestion? 
Thank you.

O Kansas
opkansas at hananet.net


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