Ian Ridgers ir at nhm.ac.uk
Fri Oct 4 09:48:32 EST 1996


Thanks to all those who responded to my question, here are snipets from
each response.

In short (for those who don't want to read further)

It would appear that -20 is ideal for storage of dried pellets for upto 3
months (at least), not that anyone every has samples sitting around that
long.... "These samples are very Important!!!"

>>I have stored dried down cycle sequenced rxns in the refrigerator for
>>a month. I also have held them at room temp for a few days.

>>ABI supplies Taq standards which sit around for months at -20 and seem to
>>work fine.  I have left them on the bench for more than a week at room temp
>>and exposed to light and they worked fine.  So long as they are dry, they
>>should last a fair time at -20.  I think the -70 is overkill

>>dry pellets at -20 are useable for at least a month after this although
>>storage does produce a decline in signal strength.

>>We store our reactions at -20, and I know they are fine for a couple of

>>The guys frm ABI told me that dried down reactions after EtOH ppt can be
>>stored at RT for many months, AS LONG AS THEY ARE KEPT IN THE DARK...

>>We store our Dye Terminator reaction after they are dry at -20.  We
>>also store the sample+loading buffer(377 samples) at -20 in case we
>>need to rerun the sample.  Can't do that with the 373 since you load
>>everything.  This seems to work well.  Usually our samples go on the
>>gell within 48 hr. of the time they are run so I dont know about long
>>term storage.  I have used the sample+loading buffer after several
>>days when we were testing new gel formulations.  They were OK.

>>I did do an experiment some years ago where I stored reactions for
>>3 weeks at -20, 4 and room temp.  The -20 was just fine.  The 4 gave
>>almost as good data and the room temp. still gave data but not as good.

>>Typically, we store dried-down reactions for less than a week at -20
>>degrees.  However, we've had reactions stay at that temp for over 3 months
>>with no loss of signal.  We also had one of those "unofficial" experiments
>>where samples sat at room temp for 3 days (in the dark...long weekend).  I
>>think the most important thing is that the STAY dried-down and should be
>>kept away from long exposures with ambient light (the dyes reduce).

>From ABI

>>dried samples at -20C they are pretty stable about 1 year...the
>>sequencing standards that we supply are stored at -20C...if in formamide:
>>don't really have any data, but I've reloaded samples a couple of weeks old
>>stored at -20 with good success.


Ian Ridgers

Dept. of Zoology
The Natural History Museum
Cromwell Rd.
London. SW7 5BD

E-mail ir at nhm.ac.uk
Tel. 0171 938 9297

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