DNA in buffer

[Jose de las Heras]

"Blunt Tool" <someone from somewhere.com> wrote in message 
news:_QdGh.6465$8U4.826 from news-server.bigpond.net.au...
>
> "Jose de las Heras" <josenet from tiscali.co.uk> wrote in message 
> news:54pftuF21t0cmU1 from mid.individual.net...
>>
>> "Blunt Tool" <someone from somewhere.com> wrote in message 
>> news:t5dFh.4699$8U4.3107 from news-server.bigpond.net.au...
>>> Hi
>>>
>>> How long can you store plasmid DNA (~6kb) in TE buffer at -20C without 
>>> no mutations?
>>>
>>> ST
>>
>> Mutations?
>>
>> You may get some degradation, perhaps, if there's some contaminant 
>> nuclease... but I don't think you'll get mutations.
>>
>> It's better to store plasmids frozen in TE than as a bacterial stock in 
>> glycerol, where you *may* get mutations.
>
> would you like to explain why this is so?
>
> ST

Plasmids, in TE, can't mutate. If there are nucleases in the buffer they may 
degrade... but if your TE is clean, you'll have plasmid for a long long 
time.
Bacterial stocks, although quite stable, are alive. If a mutation is going 
to happen anywhere, it'll be when the plasmid is in the bugs. To amplify the 
plasmid you'll streak from the stock and pick a single colony... As 
transformation is so simple, and it doesn't take longer, I don't see much 
use for having bacterial stocks at -70. Plasmids are just easier to keep.
I haven't had any problem that i could blame a mutation in the stock for, 
although I heard of others (yet, you never know how sure "others" are, too 
many myths and unfounded stories circulating around), but I don't see any 
advantage in keeping a stock like that. Plasmids alone can't mutate, are 
easier to store and handle, and transforming bugs when you need them doesn't 
take longr than growing from glycerol stocks... so I don't use them.

Jose