David L. Haviland, Ph.D. haviland at KIDS.WUSTL.EDU
Mon Nov 6 11:42:16 EST 1995

On Sun, 5 Nov 1995, CK Wen wrote:

> The department I am joining has tissue samples that have been frozen
> away for years and they want me to do RT-PCR on the samples. The
> samples were not taken originally for molecular biology and so have
> been placed in non sterile clean tubes (not autoclaved though) and were
> flash frozen in liq N2 and stored at -20 and -80. Does anyone out there
> know how long samples can be kept frozen before analysis. Will the RNA
> have degraded?
> I was planning on adding the guanadinium as the samples were thawing
> and homogenize them on thawing.

CK Wen:

Ugg!  I have no references, but about 7 years experience in dealing with
RNA.  As a general bet, you might be OK with the tubes.  However, I'll wager 
that the samples stored at -20'C are all but degraded.  I could be wrong 
but I'd have little faith in their being intact.  As long as the -70'C 
hasn't gone down (failed) then these sample might be OK.  Again, no 

What I'd suggest is that after you prep the RNA, before doing RT, run a 
quick fast formaldehyde gel with EtBr and see if the sample are intact.  
You probably already know this.

Hope this helps,
+  David L. Haviland, Ph.D.	     Internet:"haviland at kids.wustl.edu"   +
+  Washington Univ. School of Med.   A.K.A : The Compiler                 +
+  Dept. of Peds./Pulm. Box 8116     ICBM-Net : Just hit St. Louis        +
+  400 S. Kingshighway               &-6  <- User is Brain Dead...        +
+  St. Louis, MO  63110              FAX: 314-454-2476                    +
+  (314) 454-6076                                                         + 
+   -------------------------------------------------------------------   +
+                 Will clone and sequence genes for food.                 +

More information about the Methods mailing list