RNA in Formamide

Andre Hamel hamel at ccu.umanitoba.ca
Wed Feb 17 19:36:01 EST 1993


>I too refresh my oligo-dT columns in NaOH and find its
>binding capacity goes down over repeated use. I was
>interested in your formamide elution: how does one
>precipitate RNA from formamide? Add 1/10 vol NaAc and
>2.5 vols EtOH as for aqeous media?

	I'm posting my response to an email sent to me by Andy Phillips
at Ashton Research Station, Brsitol, UK. I tried emailing my response back
to him but it kept "bouncing" back ... any suggestions why?

Here's my response:

	Yes, simply add salt and alcohol as usual. RNA in formamide
behaves very much as it does in water (ONLY BETTER  :) becasue it's FAR
more stable and more convenient than in water when used for running gels
(northerns). As with water, salt will tend to precipitate if left too long
in -70oC (less than an hour is usually fine for 0.3 M NaOAc, pH 4 - pH 5,
with 3 - 4 volumes (100%) ethanol ). We usually precipitate at -20oC
overnight/weekend (or longer until needed, although the RNA is AS GOOD in
-20oC in formamide as it is in ethanol precip'n mixture.

	Although we ourselves never published on this matter (seemed like
such a common sense matter considering that everybody loads their gels
with RNA in formamide), there are several papers on this matter, the most
recent that comes to mind is by Chomczynski of all people (LOVE his
groups GITC/acid phenol RNA extraction methods) appearing in a 1992 issue
of Nucl. Acids Res. in methods section. 

>Thanks in advance
>Andy Phillips, Long Ashton Research Stn, Bristol, UK

	If you need more info please feel free to drop a note.

Cheers

Andre



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