RNA purification

[wetsel_r at msdisk.wustl.edu]

In a previous article, nelleman at biobase.aau.dk (Lars Nellemann) wrote:
>Guanidin-thiocyanat acid phenol vs. CsCl centrifugation in RNA
>purification.
>Has anyone observed that large or small transcripts are selectively 
>removed by using one of these methods.
>I have observed, that small RNAs as tRNA are removed during CsCl
>centrifugation, but not when using the guanidin thiocyanat-acid phenol
>purification.
>Has anyone observed the same, and is it possible that the reverse
>is possible, that very large RNAs are removed during acid-phenol but not 
>in CsCl centrifugation.
>Please reply at:
>nelleman at biobase.aau.dk
 ----
I've not observed this (removing large RNAs) with the acid phenol.  We have 
used the protocol (Chomczynski & Sacchi) all the time for tissue culture 
cells and have sucessfully conducted Northerns for Complement components C5 
and C3 both of which are 5-5.5 kb in length.  I have found a difference 
bewteen water saturated phenol and tris phenol, that being less of an RNA 
yeild with the tris phenol.

Hope that helps,
David

haviland at kids.wustl.edu