Often DNA is stored frozen or in slightly basic conditions. Maybe special storage solutions are used. Dry storage or ETOH may also be a solution but turns out to be too complicated for Routine use. What is your experience /advise ?
thanks for answering
I agree with Tom Masi. Store your DNA in TE buffer at -20 degree C or at -80 degree C for longer periods. Hope it helps
I totally agree with both Tom and Asim regarding intermediate to long term DNA storage. Additionally you can do one more thing. You can quantify your DNA sample and make appropriate aliquots of your DNA samples, making sure that your final DNA concentration is at least 1 microgram/ ml otherwise your DNA will degrade upon freezing thawing cycle. Hope that will be helpful. All the best.
In our lab, we store DNA at -20 ºC diluted in nuclease-free water in concentrations between 50 and 500 ng/ul for years and we never had any sample degradation problems.
Certainly 10mM Tris HCl at slightly alkaline conditions are the best for DNA storage. Fifty or 200 ng/ul are quite a lot of DNA so, small losses are negligible. However I guess René is referring to low concentrations DNA solutions. In particular I'm thinking of the highest diluted in a ten-fold dilution series used in calibration curves for qPCR. These can be up to femtograms DNA/ul. Losing femtograms from a 50ng/ul is imperceptible but it is not from these 10⁻⁵ or 10⁻⁶ tubes.
At very low concentrations we have also experienced higher Cq values (even loss of amplification) after certain storage time, even at the recommended conditions.
Since DNAases are absent from the solvent (Tris HCl) if it has been properly autoclaved, my hypothesis about the causes of this problem is that there is some sort of physical (adsorption) or chemical or electrical interaction with the plastic tube wall. At pH 8.0 or 8.1 DNA is negatively charged (phosphate is ionized) so it can be easier dissolved, but also it might have interactions similar to those with silica membranes. The use of EDTA may worsen the problem since Na+ can be a factor as it is with Silica DNA binding.
Sorry for the length of this answer. Any other hypothesis?
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