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
>>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
Thomas T. Aquilla, Ph.D. .***. .***. .***. .***.
Molecular Physiology and Biophysics * | | | * * | | | * | | | *
University of Vermont Medical College* * | | | * * | | | * * | | | *
Health Science Complex, Given E-201* * | | | * | | | * * | | | *
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