Steve Griffiths sgriffit at rpc.unb.ca
Fri Nov 29 09:50:16 EST 1996

In article <57j7em$5km at mserv1.dl.ac.uk>,
   Dr Alok Adholaya <aloka at teri.ernet.in> wrote:
>I would like to know if the DNA extracted by using CHELEX-100 resin
>( Biorad CA) and subsequently
>used for PCR amplification is stable if yes for how long ???  I am
>having a problem at this end as i am using  the DNA extracted from
>this resin for RAPD work. Now repeated freeze thaw cycle of the
>extracted DNA does not seem to give a reproducible fingerprint. To
>check that there is no problem with the PCR i used fresh prep and
>did the RAPD and bingo  the original fingerprint pattern. Could
>repeated freeze thaw cycle of the DNA extracted from CHELEX would
>not be desirable if your final goal is  critical like fingerprint (
>RAPD ). I have had no problem when using some specific primers,
>consistent amplification was obtained from an older extracted prep.
>Dr Alok Adholeya
>Fellow, TATA Energy Res Inst
>Habitat Place, Lodi Rd
>New Delhi 110003 INDIA
>FAX: 91-11-462 1770/463 2609
 There is no doubt in my mind that something odd happens to chelex 100 
extracted DNA during freezing.we have tried to save aliquots of bacterial 
DNA for a semiquantitative assay.It looked as if as time went on(ie 
months in the freezer) that we couldn't get an amplification signal from 
16s rna genes at progressively lower dilutions in PCR water.Although we 
love it for diagnostic applications (BioRad's INSTAGENE) this is the only 
problem we've had so far.
   Stay Frosty

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