Anomalous PCR product

Dr. Duncan Clark duncan at
Fri Dec 13 06:59:50 EST 1996

In article <58pqqc$kpt at>, The Great American
Gene Company <geneco at> writes
>Dear Folks:
>I was just contacted by a colleague with the following question.  It is
>not my field of expertise, but I believe that it is similar to a topic
>recently discussed here.  Can we have your comments and/or
>observations?  Both Neal and I would greatly appreciate any help you
>can provide.
>Posted for Neal Cornell:
>>        I have used an oligo for PCR which resulted in a major,
>>product of 600 bp.  The same  600 bp product was generated when no
>second primer >and no template DNA was put through the "PCR".  Do you
>have any experience to >suggest what might be causing this?
>Thank you kindly,
>Michael T. MacDonell, Ph.D.

The first primer is priming to some DNA being added or present in the
PCR tubes. There is no easy way around this other than changing
everything ie water, tips, autopipettes ('cos any DNA/phage in the
barrel could be transferred by aerosol), nucleotides etc. You will also
find that all commercial DNA polymerases have a few copies of Xsomal DNA
co-purified with them - they are after all DNA binding proteins. You
could change one thing at a time but will take time to track it down.
Prepare your PCR's in another room etc etc. UV irradiation of reagents
may also help. 


The problem with being on the cutting edge is that you occasionally get 
sliced from time to time....

Dr. Duncan Clark
DNAmp Ltd.
TEl/FAX 01252376288

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