Re: how to test your dinosaur bones for DNA

[cpretzma@magnus.acs.ohio-state.edu (Chip Pretzman)]

Mickey Rowe wrote:

>The first is just a brief description of the second.  I'll be even
>briefer: it appears that we're unlikely to get interpretable DNA
>directly from dinosaur bones.  ...

>Somehow I expect to hear from Chip Pretzman on this one...

Oh yes, just keep an eye out for a 'letter to the editors' from yours
truly in one or another high level journal.  I will say this for those
on the server:

There is no genetic sequence data presented.  They tested Woodward's
and Schweitzer-Horner's bones and got "no meaningful DNA."  I still
don't know what "meaningful DNA" means, since the authors did not show
haow they analyzed recovered DNA for meaningfulness.  If Woodward and
Schweitzer recovered contaminant seuqences, how come Poinar
et. al. did not?  Everyone talks about independent confirmation of
ancient DNA sequence, but the door swings both ways; Where is the
independent confirmation of contaminants?  Another thing the authors
did not do was to show that their technique actually worked.  They
showed no ancient DNA sequences, and only referred to other peoples'
work.  Also, their amber was only 'similar' to that used by others.

My major criticism is that the authors are assuming that the DNA
extraction, purification, amplification and sequencing procedures were
reliable.  There is much to be done in improving recovery techniques,
and it is very possible that their failure to recover "meaningful DNA"
was due to unforeseen technical limitations of their DNA procedures.
This, also, they failed to discuss.  The PCR can theoretically detect
single pieces of DNA, so I suspect that there is a big gap in
sensitivity between their amino acid analyses and optimum PCR testing.

All in all, a very negative article which will do nothing but
discourage potential researchers from pursuing the recovery of DNA
from ancient sources.

Chip Pretzman
Dept. of Molecular Genetics
Laboratory of Evolutionary Genetics
The Ohio State University