Can Taq use RNA as a template?

Nick Theodorakis nicholas_theodorakis at urmc.rochester.edu
Fri Sep 10 09:43:59 EST 1999


In article <37D93AD2.31D4 at le.ac.uk>,
  "A.F. Simpson" <AFS7 at le.ac.uk> wrote:
> Greg Appleyard wrote:
> >
> > Can Taq act as a DNA polymerase using RNA as a template?
> >
> > We are curious about the origins of amplified fragments following PCR in
> > our RNA+ but cDNA and DNA negative control lane.
>
> My first suspicion would be DNA contamination of your RNA.
>
> What exactly are you trying to PCR and what is the source of your RNA?
>
> > Greg Appleyard
>

The original post didn't mention whether the expected PCR fragment is
the size expected from a processed mRNA or from genomic DNA, or what the
source of his RNA is, but note that in many mammalian genomes there are
sometimes "processed" pseudogenes which have no introns, and would give
the same size PCR band as one would get from amplifying cDNA. I've
noticed that I sometimes get this at a low level with beta-actin in
mouse cells.  It's hard to guarantee that your RNA is absolutely free of
all genomic DNA contamination, especially if you use a "total RNA"
method such as GITC, Trizol, etc.

Nick


--
 _______________________________________________
| Nick Theodorakis                              |
| nicholas_theodorakis at urmc.rochester.edu       |
| (previously theodorn at gusun.georgetown.edu)    |


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