Isolating DNA
*For isolating genomic and plasmid DNA from cells and tissues, use fresh samples or samples that have been stored at or below -70°C. This reduces nuclease activity.
*For blood preparations, use fresh blood. If the blood is stored, it shouldn't be for more than two days at room temperature, one week at 4°C, or one month at -20°C, and even then DNA yield will still be reduced.
*Collect blood samples in tubes containing heparin as an anticoagulant may disrupt PCR work later. Try to use EDTA instead.
Storing DNA
*For genomic DNA, storage at -20°C can cause shearing, so store it at 4°C.
*For plasmid DNA, 4°C storage is good for the short term and -20°C for the long term.
*Plasmids that are used for transformation should be stored at 4°C to avoid nicks.
*Store modified DNA at 4°C.
Dissolving DNA
*Dissolve DNA in a Tris buffer (such as a 10 mM, pH 7-8 buffer).
*If it doesn't dissolve well, gently invert and/or tap the tube several times. Alternatively, leave it overnight at 4°C. Do not vortex genomic DNA!
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