Proteins derived from tyrannosaurus bone
Collagen remains detected for the first time from 68 million year old fossilsRead out
Jurassic Park leaves its mark: American researchers have succeeded in extracting organic tissue from a 68-million-year-old leg bone of a Tyrannosaurus rex and even detecting proteins in it. These results, which are now published in "Science", throw previous assumptions about the properties of fossil bones over the pile and open up new possibilities for paleontological research.
Bone is a composite material that consists of both minerals and organic compounds, including proteins. When the mineral constituents are removed, an elastic but resistant collagen matrix remains. Exactly this rubbery tissue found scientists of the North Carolina State University under the direction of Mary Schweitzer to their great surprise even after the demineralization of T. rex bone. The bone is part of a T. rex skeleton found in 2003 in the Hell Creek Formation in Montana.
Protein residues identified
Surprising is the finding of the organic tissue remnants, because it was previously assumed that in fossil bones of this age, no such material has survived. After extensive chemical and molecular analyzes, it was suggested that indeed protein fragments could have been obtained in this tissue. But which proteins was it? Could it be collagen?
"We were looking for collagen because it's usually abundant and stable and has been found in younger fossil bones, " says Schweizer. "It's also a molecule that's easy to detect and that has not been produced by microbes around the bone. Therefore, when we identify collagen in soft tissue, it actually has to come from the T. rex - the bone contains remnants of the dinosaur's molecules, albeit altered by age. "Display
Collagen is similar to that of frogs and chickens
To see if the resulting material also has the characteristic collagen-like "stripes, " Schweizer and her colleagues examined the tissue both electron microscopically and with an atomic force microscope. In addition, they tested the response of the matrix with various antibodies that specifically respond to collagen. But only after mass spectrometric analysis, the researchers could finally confirm that they actually had 68 million years old collagen in front of him.
This method measures the charge ratios of individual protein building blocks and makes it possible to deduce the amino acid sequence of the protein from the sequence of these charges. Since mass spectrometry can be used even for very small sample volumes, even the tiny T. rex sample was able to detect parts of the collagen sequence. The comparison with the modern animals showed a similarity with the collagen sequence of chicken, frogs and newts.
"The similarity to the chicken is definitely what we would expect given the relationships between modern birds and dinosaurs, " explains Schweizer. "From a paleontological point of view, these data are the icing on the cake, proving the conservation of dinosaur tissue. They will help us to learn more about the evolutionary relationships of dinosaurs, how conservation happens, and how molecules degrade over time. "
(North Carolina State University, 13.04.2007 - NPO)