Contaminated -Taq

un691cs at un691cs at
Tue Feb 10 04:47:54 EST 1998

On 9 Feb 1998 15:50:34 -0800, Michelle Gleeson said:

>I have had a similar problem, which I did isolate to contaminating DNA in
>the Taq.  The primers were for prokaryotic type rDNA, and although they
>were specifically designed for plastid, they amplified a lovely band in
>the neg control.  I cloned and sequenced it, and it was E.coli SSUrDNA.
>Identical, absolutely no question.

>SInce it was recombinant Taq, it was
>clearly remnants left over from the purification, and given the copy
>number of this gene, it wouldn't take much to cause a problem.

Hmmm. I had the same problem with RT-PCR. I was trying to amplify 
plant mRNA species with one specific and one polyA primer: ended
up cloning a mouse histone mRNA. I presumed at that time that
the superscript locus contained some sequence information of
that gene, which was also present in e.coli. Or mice had been
nibbling at the plants, a less likely explanation.


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