PCR,DNA storage for.

Brian Foley brianf at med.uvm.edu
Wed Jun 22 09:40:03 EST 1994

Monica J. Martick (mmartick at moose.uvm.edu) wrote:
: Hi,
: I have read about several ways to store genomic DNA for PCR.
: I store it in dH2O at 1 degree C. I heard that storing in Tris HCl
: prevents DNA degradation for a longer period of time, but I am not sure
: how this would effect the outcome of PCR. If I store in Tris HCl, do I
: have to readjust the salt concentration? Also, do you know what is the best
: temperature to store genom. DNA for PCR?

: Monika
: My address: mmartick at moose.uvm.edu

	Water is OK, if you have very good water (sterile and clean). 
Storing you DNA in Tris-buffered water is virtually the same, except
that you can control the pH (distilled water has a pH of about 5.0
if any CO2 such as atmospheric air has contacted it, forming carbonic 
acid in the water)
	I personally store my mammalian cell genomic DNA in Tris-buffered
water pH 8.0, (10 mM Tris) with 1 mM EDTA also at pH 8.0  
	The 10 mM Tris does not seem to affect PCR at all.  The 1 mM EDTA
is a larger factor because divalent cations are needed by the polymerase, 
but since I am adding less than 5 microliters of genomic DNA solution to
a 100 microliter reaction, the EDTA contibution is minimal, considering that
I am adding Mg++ at various levels from 1 to 10 mM final concentration.

	I have stored some DNA samples for more than 5 years at 4 degrees
centigrade, and it still amplifies fine.  Other samples went bad after a 
few months.  I suspect bacterial or enzymatic degradation in the samples
that went bad.  I'm sure that even my purest DNA preps have some protein
contamination, of which some of the protein could have nuclease activity.

*  Brian Foley               *     If we knew what we were doing   *
*  Molecular Genetics Dept.  *     it wouldn't be called research  *
*  University of Vermont     *                                     *

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