Here is a scientific press release with info which could help more
data be gleaned, esp. from fossils which may look very similar but may
be different genetically. Ferret ancestors are among groups in which
the animals can look similar but be reasonably different genetically.
Advances can at times hold great promise, and this one might.
(BTW, the type of mammal with the greatest speed of added genetic
variation is the vole (not mole, but vole) yet voles all tend to
look greatly like each other.)
Some common (and long standing) methodologies reduce the genetic
material with which these specialists can work. (Digs involve people
with many different specialization focuses, all working together, so
new techniques by one or more specialization do require changes in
methodology by others. No one does everything though some may try, and
certainly no one does everything well, due to the level of information
and expertise unique to each field involved.)
http://www.eurekalert.org/pub_releases/2007-01/c-tme011707.php
Press Release in full:
Public release date: 17-Jan-2007
Contact: Monica McCarthy
[log in to unmask]
33-144-965-191
CNRS
Toward more effective paleolgenetic analysis
DNA preserved in bones undergoing fossilization deteriorates up to 50
times faster when stored in a museum than when the bones are buried in
the ground. This has just been shown by a paleogenetics team led by
Eva-Maria Geigl (Institut Jacques Mono / CNRS -- Paris). This study,
which was published in the Proceedings of the US National Academy of
Sciences 8 January 2007, shows that in order to improve the quality
of paleogenetic analyses, archeological and paleontological remains
should be treated like biological samples both during and after
excavation. The findings show the need for a new methodology for the
excavation, treatment and preservation of fossils. They also open
up new prospects for paleogenetic research into freshly excavated
fossils.
In paleogenetic research, it is essential to have well-preserved
archeological material in order to obtain reliable results. At
present, such research is only too rarely the result of close
collaboration between the various disciplines involved: molecular
biologists, archeologists, paleontologists and curators. Moreover,
biologists mostly carry out such studies on samples stored in
collections or in museums. However, there was no reason to suppose
that the treatment carried out by fieldworkers (archeologists,
paleontologists and curators), as well as storage conditions, were
compatible with a paleogenetic approach. In fact, such analyses were
often subject to a high failure rate, due partly to a lack of any
ancient DNA detected by PCR , or to contamination by modern DNA.
An extensive study of around 250 fossil bones from 600 to 50 000 year
old herbivores was carried out thanks to international cooperation
between the Institut Jacques Monod at CNRS, the Museum of Natural
Sciences in Madrid and a number of European, Turkish and Japanese
paleontologists and archeologists. The work showed that mitochondrial
DNA from freshly excavated, untreated fossil bones was amplified with
a success rate of 46%. However, the rate is a mere 18% for fossil
bones from collections which have been washed, dried and stored. A
large part, on average 85%, of the genetic material preserved in the
fossils is therefore lost as a result of treatment by archeologists
and storage in museums.
These findings were confirmed by a study on fossil bones from a single
animal, an aurochs which became buried 3 200 years ago in the Sarthe
region of France. The fossil bones were excavated during two
excavation campaigns, the first carried out in 1947, and the second
in 2004. Convinced by Geigl that it was necessary to analyze freshly
excavated fossil bones, Nicolas Morel, a paleontologist and curator of
the Muse Vert in Le Mans looked up the location of the site of the
1947 excavation in the records, and then collected an extra 120
freshly excavated fossil bones from the aurochs. None of the fossil
bones excavated in 1947 and stored in the Muse Vert yielded any
results from paleogenetic analysis. On the other hand, DNA
amplification was obtained with all the 2004 fossil bones, thus
yielding significant results from paleogenetic analysis. Another
finding revealed by this study was that the DNA had deteriorated as
much in 57 years as during the previous two thousand years of burial.
A rise in temperature and a fall in pH and salt concentration as a
result of being washed are the main factors put forward in order to
explain the increasingly rapid deterioration of the DNA taken from
treated bones.
An interdisciplinary approach involving close collaboration between
molecular biologists and fieldworkers led to this important discovery.
This opens up the prospect of more extensive paleogenetic analyses,
regarding both the length of the time periods that can be analyzed as
well as the variety of questions that can be tackled. This is because
until now information has mainly been obtained from samples from
cold regions, since DNA is better preserved at low temperatures. By
analyzing freshly excavated fossil material, it should be possible
to recover genetic information from specimens from warm or temperate
regions such as the Middle East and Africa, regions where there is
potentially a wealth of information about the development of our
civilization and about human evolution.
Eva-Maria Geigl carrying out an excavation under aseptic conditions.
(c) E.-M. Geigl - CNRS 2007 (this image can be obtained from the
CNRS photo library (photothque du CNRS, 01 45 07 57 90,
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REFERENCES Freshly excavated fossil bones are best for amplification
of ancient DNA (2007). Mlanie Pruvost, Reinhard Schwarz, Virginia
Bessa Correia, Sophie Champlot, Sverine Braguier, Nicolas Morel,
Yolanda Fernandez-Jalvo, Thierry Grange, and Eva-Maria Geigl. Proc.
Natl. Acad. Sci. USA. Published online 8 January 2007.
CONTACTS
Researcher contact
Eva-Maria Geigl
T 01 44 27 57 07
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Press contact
Priscilla Dacher
T 01 44 96 46 06
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I am hoping for some cool new data now that these aspects can be
taken into account in future digs.
[Posted in FML 5491]
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