In article <DHGorC.FyA at news.tcd.ie> Dr David E Barton,
dbarton at acer.gen.tcd.ie writes:
>Subject: Re: Storage/stability of DNA
>From: Dr David E Barton, dbarton at acer.gen.tcd.ie>Date: Fri, 3 Nov 1995 09:52:23 GMT
>>Query posted regarding degrading DNA
>>>We would like to be able to keep the DNA samples for at least several
>>>years without significant degradation. Any comments or suggestions
>>>regarding suitable storage techniques would be appreciated.
>>It seems unlikely that your DNA is actually degrading during storage at -70C.
>Try heating the DNA to 65C for 15min to kill any nucleases before adding any
>restriction enzyme buffer. In my experience, once you add the RE buffer, any
>contaminating nucleases get activated. The Chloroform idea is also good if you
>must store at 4C, but it is not a permanent solution.
>>Best wishes, David.
I recently dug some old plasmid DNA out of the -70 freezer. It had been
there continuosly for nearly six years without being thawed. The material
fine except for one problem...it would not cut with any of three or four
enzymes I tried! In the end I re-transformed the plasmid into bugs and
fresh DNA. I do not have an explanation for this observation. The DNA was
before storage. However, as a means of maintaining the integrity of the
DNA, -70 storage
would appear to be a good way of doing it.