T. rex DNA

[stssram@st.unocal.com (Bob Myers)]

Ok, evidently it's time for a repost of some articles from last year.
T. rex was chosen due to the unusual state of preservation, not the
"mystique" or whatever of T. rex.


--- Forwarded mail from John Matrow <jmatrow@donald.wichitaks.NCR.COM>

>From jmatrow@donald.wichitaks.NCR.COM Thu Jul  8 07:46:31 1993
Subject: Blood cells from T. Rex bones (fwd)
To: dinosaur@donald.wichitaks.NCR.COM
Date: Thu, 8 Jul 93 8:06:44 CDT
From: John Matrow <jmatrow@donald.wichitaks.NCR.COM>
X-Mailer: ELM [version 2.3 PL8]

Forwarded message:
> 
> The Sydney morning Herald reported that scientists in the USA had found blood
> cells on the fossilized bones of a T. Rex and that they hoped to get some DNA
> from them. Can anyone in the States confirm this?
> 

IS DINOSAUR DNA MORE THAN STUFF OF MOVIES?
By Malcolm W. Brown
New York Times News Service
July 1, 1993

   A  Montana paleontologist and his colleagues think  they  have 
found   red  blood  cells  in  the  fossilized  leg  bone  of   a 
Tyrannosaurus rex and say they have high hopes of extracting  DNA 
from the dinosaur's cells.
   The discovery of the putative dinosaur blood cells has not yet 
been submitted to a scientific journal or independently confirmed 
but   was  reported  two  weeks  ago  by  the  National   Science 
Foundation, which has financed the project.
  Jack  Horner, a paleontologist at Montana State University  who 
directed  the investigation, said Wednesday that his group  hoped 
to  find  matches between gene fragments left  in  the  preserved 
blood  cells with comparable DNA segments from modern  crocodiles 
or birds.
   "If  we're  lucky  enough to find  matches,"  he  said,  "they 
could go a long way toward showing what the relationship  between 
dinosaurs  and birds might be. We're not there yet, but we  think 
we're getting close."
   Cheryl   Dybas,  a  spokeswoman  for  the   National   Science 
Foundation,  acknowledged  that  her  agency  had   intentionally 
released  its  report of Horner's progress to coincide  with  the 
opening of "Jurassic Park," a science-fiction movie based on  the 
premise  that  dinosaurs  might  one day  be  cloned  from  their 
surviving DNA.
   The femur, or leg bone, Horner's group is studying is part  of 
an  unusually  well-preserved tyrannosaur fossil,  more  than  65 
million  years old, which they found and excavated from the  Hell 
Creek Formation in eastern Montana three years ago. The  apparent 
blood cells were discovered by Mary Schweitzer, Horner's graduate 
student, who was investigating the histology, or cell  structure, 
of fossilized bone and marrow tissue.
   In  the  past,  few paleontologists  or  molecular  biologists 
believed  that biological material could survive for millions  of 
years  without  becoming  mineralized, thus  losing  its  organic 
molecular  structure.  The  survival of  any  intact  DNA,  which 
ordinarily  decays  with time, seemed even less likely.  But  the 
recent discovery of organic material and even fragments of DNA in 
ancient plant and animal fossils has changed opinions.
   "Two  years ago I would have called this baloney,"  said  Raul 
Cano  of  California  Polytechnic State University  at  San  Luis 
Obispo,  a  molecular  biologist who has  himself  extracted  DNA 
fragments  from fossilized insects and plants millions  of  years 
old.
   "It's  certainly plausible," Cano said. "We have seen  similar 
things  ourselves."  Earlier this month Cano and  his  associates 
reported in the journal Nature that they had extracted DNA from a 
weevil  that  had been entombed in amber for 120 million  to  135 
million years.
   Molecular   biologist  Russell  Higuchi,  who   has   strongly 
questioned  the premise that appreciable quantities of DNA  could 
survive  for  eons,  said Wednesday that  it  was  possible  that 
Horner's group has actually seen dinosaur blood cells.
   "We  ourselves  speculated 10 years ago that if  dinosaur  DNA 
survived  at all, it might be found" deep inside a  fossil  bone, 
said Higuchi, of Roche Molecular Systems in Alameda, Calif.
   Horner  said  that  microscopic examination of  a  thin  slice 
through the dinosaur bone revealed that although its outer layers 
were mineralized, the bone itself, brown in color, remained  more 
or less intact in the interior of the marrow cavity.
   Mary  found spherical structures that appear to  be  nucleated 
red  cells  inside the blood vessels running  through  the  bone, 
right where you'd expect to find blood, if it's there," he said.
   Part of the science foundation's grant to Horner's group  went 
for laboratory equipment to conduct a polymerase chain  reaction, 
a technique that can single out a lone molecular fragment of  DNA 
and  make  enough  copies so it can be  analyzed  using  standard 
methods.
   "The biggest problem is contamination of the fossil by foreign 
DNA,"  Horner said. "There's lots of it there. The real trick  is 
in  identifying something that is not a contaminant. This is  why 
we  are  looking for matches with crocodile DNA, which is  not  a 
likely contaminant."

-- 
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 316-636-8851 <John.Matrow@WichitaKS.NCR.COM>
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