The Case of the Vanishing Intron

Klaus Salger salger at
Thu Nov 10 18:32:33 EST 1994

Thierry Nouspikel (nouspike at wrote:
(stuff deleted)
: - My PCR reaction has been contaminated
:   by RNA (but it wouldn't serve as a template without previous RT,
:     would it ?)
:   by cDNA from the parallele RT-PCR reaction.
: BUT this does not explain why I don't see the regular 605bp genomic
:  band in #2.
(more stuff deleted)

Yes, it would. Taq has some reverse transcriptase activity. I found two
references about that.
Jones+Foulkes, NAR 17, p.8387
Tse+Forget, Gene 88, p.293
(I didn't find them neither in the "Maniatis" nor in one of 2 special
PCR-books but in the USB catalogue!)
Maybe you want to treat your DNA with RNase to exclude this possibility?
The absence of the 605bp band could be explained by assuming that something
is wrong with this particular DNA-prep. Or did you already amplify something
else from this prep?

If you find the explanation, please post it!

Klaus Salger                phone : ++49 (0)89 5902 -502
Zoologisches Institut       FAX   :                 -450
AG MacWilliams              e-mail: salger at
Luisenstr. 14
80333 Muenchen

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