New Technique to Identify Protein in Ancient Dinosaur

A novel study provides evidence for the preservation of ancient dinosaur proteins, including reactivity to antibodies that target specific proteins normally found in bone cells of vertebrates. 

The results of the study that was conducted by a team of researchers from North Carolina State University and the Palo Alto Research Center (PARC) further rule out sample contamination, and help solidify the case for preservation of cells and possibly DNA in ancient remains.

It was in the year 2005 that the preserved soft tissue in a 67 million year old Tyrannosaurus Rex was discovered by Dr. Mary Schweitzer, professor of marine, earth and atmospheric sciences with a joint appointment at the North Carolina Museum of Natural Sciences.

Subsequent research revealed similar preservation in an even older Brachylophosaurus Canadensis that is 80 million year old.

In 2007 and again in 2009, Schweitzer and colleagues used chemical and molecular analyses to confirm that the fibrous material collected from the specimens was collagen.

Next, Schweitzer's tried to trace if the star-shaped cellular structures within the fibrous matrix were osteocytes, or bone cells. With the help of techniques such as microscopy, histochemistry and mass spectrometry, Schweitzer demonstrates that these cellular structures react to specific antibodies, including a protein known as PHEX.

Phex is found in the osteocytes of living birds.

"The PHEX finding is important because it helps to rule out sample contamination," Schweitzer says. "Some of the antibodies that we used will react to proteins found in other vertebrate cells, but none of the antibodies react to microbes, which supports our theory that these structures are surviving osteocytes. Additionally, the antibody to PHEX will only recognize and bind to one specific site only found in mature bone cells from birds. These antibodies don't react to other proteins or cells. Because so many other lines of evidence support the dinosaur/bird relationship, finding these proteins helps make the case that these structures are dinosaurian in origin."

Apart from this the team looked for the presence of DNA within the cellular structure using an antibody that only binds to the backbone of the DNA and this anitobody  reacted to small amounts of material within the "cells" of both the T. rex and the B. canadensis.

In an attempt to wipe away the microbes, they used an antibody that binds histone proteins, which bind tightly to the DNA of everything except microbes.  The two histochemical stains were treated with flurosce when they attach to DNA molecules. Those tests were also positive. 

"The data thus far seem to support the theory that these structures can be preserved over time," Schweitzer says. "Hopefully these findings will give us greater insight into the processes of evolutionary change."

 The findings appear online in Bone and were presented last week at the annual meeting of the Society of Vertebrate Paleontology.