The answer, dmiceo, depends on the type and condition of the sample
containing the DNA. Some species?s DNA is more fragile than others,
while some kinds of specimens themselves are more susceptible to
damage. Bacteria, fungus, and chemical reactions can degrade a DNA
sample, as can pH changes. In DNA specimens that were slowly frozen
and remained frozen, DNA integrity can be preserved far longer than
had the sample been quickly frozen, and thawed, then refrozen.
http://www.ncc.gmu.edu/dna/composit.htm
?The major part of DNA degradation happens within autolysis, a few
hours or days after the death of the organism.? Page 3 of the Adobe
.pdf document. This document goes on to explain storage conditions.
http://www.uni-mainz.de/FB/Biologie/Anthropologie/dna.pdf
Blood and buccal (inside facial cheek) cells stored on cotton paper
have maintained DNA integrity for up to 6 months at room temperature.
http://flinderstech.flinders.edu.au/dna/DNA%20integrity.pdf
"DNA is hardy and highly transferable. How long DNA lasts for is
"totally dependent on the environmental conditions it exists in. Dry
and cool it can last for centuries," says Dr McDonald.?
http://www.arts.monash.edu.au/humcass/independentjournal/sinclairk_knowwherednais.html
DNA has been recovered from frozen mammoths that are millennia old.
Most of the DNA found in mammoth skin samples has been damaged from
exposure, while bone and dental DNA is often better preserved. Had the
DNA been stored according to today?s standards, it could possibly
survive millennia! Different animal and human carcasses have been
found, with varying degrees of intact DNA. A slow freeze, along with a
slow thaw is the best way to preserve DNA, and is the method followed
by laboratories.
http://www.trussel.com/prehist/news298.htm
http://www.priweb.org/ed/ICTHOL/ICTHOL04papers/19.htm
http://www.buzzle.com/editorials/7-16-2003-42987.asp
This is an Adobe .pdf document, that is very slow to load - please be patient!
http://research.amnh.org/amcc/cbc_ark.pdf
?Similarly, thawing and refreezing biological specimens can place
stress on the three dimensional structure of all the components in the
mixture. Furthermore, multiple freeze/thaws can change the activity of
enzymes, or alter protein binding properties. Freezing cells or
tissues can also result in altered morphology such as broken plasma
membranes and displacement of antigens to remote locations?
http://www.biophileinc.com/php-bin/faq/index.php?category_id=19
?The most ancient Neanderthal to furnish a DNA sequence, from a site
in Croatia, dates to over 42,000 B.P. Nuclear DNA has been taken from
human remains this ancient, but no one has yet been able to
reconstruct human nuclear DNA sequences this old. Hope for such
sequences exists, however, since cave-bear remains some 33,000 years
old have yielded a nuclear DNA sequence (Greenwood, et al, 1999). It
is easier to study mtDNA from ancient bones, because many
mitochondria, and therefore many copies of the mtDNA molecule, exist
in a cell, compared to only a single copy of the nuclear genome.?
http://www.neanderthal-modern.com/genetic2.htm
This article dates the frozen DNA at 20,000 years old, and says it was
well preserved.
http://www.cbsnews.com/stories/2003/07/15/tech/main563450.shtml
From the University of Alberta, Canada ?These results demonstrate that
aDNA can be extracted from fossils of up to 100,000 yr if found in a
suitable environment (dry, oxygen deprived, and cold) to minimize DNA
damage. These results also show that aDNA can be useful in determining
phylogenies of extant and ancient species although more than one
sample would, of course, be preferred for the purposes of comparison.?
http://www.biology.ualberta.ca/courses.hp/biol606/OldLecs/Lecture.98.12.Wilson.html
Now, what if you DO have millennia-old DNA? Would you be able to
recreate an IceMan or an extinct species? Probably not, as chunks of
DNA do not a living being make! Once cellular death has occurred, DNA
becomes nothing more than strands. Scientists can study this DNA to
get a picture of past beings, and some DNA can be amplified to try and
make it ?whole? again, but as of yet, cloning a creature from long ago
has not been successful.
?Scientists have recently found a fully-grown male mammoth frozen in
the tundra of Siberia for more than 20,000 years. They have hopes of
cloning the mammoth from the DNA found in the carcass, or of
impregnating an elephant if they find viable sperm.
At least in theory, a pairing of mammoth sperm and the egg of an Asian
elephant could produce an offspring. There is less than a 5 percent
difference between the genetic makeup of the two animals. The
resulting creature would be half-mammoth, half-elephant, but over
time, selective breeding of mammoth-elephant hybrids might produce a
nearly pure mammoth. In the best-case scenario, a mammoth hybrid could
be born within two years.?
http://www.straightdope.com/mailbag/mfrankenstein.html
http://nene.essortment.com/woolymammothss_rmio.htm
http://www.salon.com/tech/feature/2002/01/03/mammoth/index2.html
This well done site, by the Tech Museum of Innovation by EPIC:
Electronic Publishing Instructional Curriculum at the University of
California, Santa Cruz explains DNA. While not answering your
question, it is very informative.
http://www.thetech.org/exhibits/online/genome/index2a.html
A DNA Timeline
http://www.accessexcellence.org/AB/WYW/wkbooks/SFTS/sidebarmilestone.html
An interesting item I found while researching your answer:
?Cloud believes frozen sperm should last more than 200 years?
http://www.bluefish.org/frosperm.htm
To summarize, viable DNA can be found up to 6 months later, at room
temperatures, while frozen DNA, especially if properly stored, can
last for thousands of years, or millennia!(A millennium is one
thousand consecutive years). Since scientists have only begun to store
frozen DNA under optimal conditions for the last 35 years, it remains
to be seen exactly how long DNA can remain viable!
I hope this answers your question! If not, please use the Answer
Clarification button, before rating this answer. This will allow me to
assist you further, if possible.
Regards,
crabcakes
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