IUBio Biosequences .. Software .. Molbio soft .. Network News .. FTP


Tracy Aquilla aquilla at salus.med.uvm.edu
Mon Nov 13 11:38:53 EST 1995

In Article <47ngpb$1l3 at sun168.rz.ruhr-uni-bochum.de>,
stefan.harjes at rz.ruhr-uni-bochum.de wrote:
>hjs at renal.wh.su.edu.au (hjs) 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. 
>My experience is: samples should be flash frozen in n2 and kept at at
>least -80. After about a month degadation is sometimes visible (on
>northern blots) but i have done rt-pcr on samples as old as a year.
>You better throw away the samples stored at -20!

I wouldn't follow this recommendation until you confirm that the RNA is too
degraded to be of use. I've isolated excellent quality RNA from tissues
stored at -20 for several months. I've also found on occasion that purified
RNA stored in water at -20 for years was of acceptable quality for
Northerns. I once received a package that sat on the loading dock over the
entire weekend. The RNA (in water) had thawed and I was pretty sure it
wouldn't be any good. It was fine. Don't toss it out until you're sure it's
no good.

Thomas T. Aquilla, Ph.D.         .***.   .***.           .***.   .***.
Molecular Physiology and Biophysics    * | | | *       * | | | * | | | *
University of Vermont Medical College*   * | | | *   * | | | *   * | | | *   
Health Science Complex, Given E-201*       * | | | * | | | *       * | | | *
Burlington, VT 05405-0068    '***'           '***'   '***'           '***'

More information about the Methods mailing list

Send comments to us at biosci-help [At] net.bio.net