DNA extraction - (Jul/06/2006 )
Why can I must store DNA extracted from tissue at 4oC? Why can't I freeze? Is storing at -20oC considered as freezing? Won't storing at -20oC prolong shelf-life of DNA?
I think -20 is better for storage, but there is an issue with freeze thaws if you are using the same aliquot several times in and out of the freezer. This is a real problem with RNA, but not as bad with DNA.
I store DNA at 4C if it is in TE or Tris
If in Water, store at -20C
I store mine in TE at -20 and have never had a problem with it (although I rarely freeze-thaw multiple times).
I've done both ... working samples in TE were generally stored in 4C, but we also stored the DNA also in TE in -20C for more long term storage. The DNA generally was fine (I think more problems dealt with the integrity of the sample in the first place than from the storage in -20 and thawing). We always aliquoted enough so that there was usually more than one of the same sample so there wouldn't be the freeze thaw issue.