Evidence of proteins, chromosomes and chemical markers of DNA in exceptionally preserved dinosaur cartilage
Alida M Bailleul, Wenxia Zheng, John R Horner, Brian K Hall, Casey M Holliday, Mary H Schweitzer
National Science Review, nwz206, https://doi.org/10.1093/nsr/nwz206
Published: 12 January 2020
Photographs of cartilage cells from skull of Hypacrosaurus nestlings. On the left, two cells at the end of cell division are seen, with material consistent with condensed nuclei. In the center, a higher magnification image of another cell shows chromosomes. On the right is an isolated dinosaur cartilage cell that reacts with the DNA stain Propidium iodide (red dot, inside the cell). This stain suggests there is still endogenous dinosaur DNA in this 75 million-year-old cartilage cell. Photo credit: Alida Bailleul and Wenxia Zheng Credit: ©Science China Press
Abstract
A histological ground-section from a duck-billed dinosaur nestling (Hypacrosaurus stebingeri) revealed microstructures morphologically consistent with nuclei and chromosomes in cells within calcified cartilage. We hypothesized that this exceptional cellular preservation extended to the molecular level and had molecular features in common with extant avian cartilage. Histochemical and immunological evidence supports in situ preservation of extracellular matrix components found in extant cartilage, including glycosaminoglycans and collagen type II. Furthermore, isolated Hypacrosaurus chondrocytes react positively with two DNA intercalating stains. Specific DNA staining is only observed inside the isolated cells, suggesting endogenous nuclear material survived fossilization. Our data support the hypothesis that calcified cartilage is preserved at the molecular level in this Mesozoic material, and suggest that remnants of once-living chondrocytes, including their DNA, may preserve for millions of years.
Keywords cartilage, dinosaur, nuclei, chromosomes, collagen II, DNA markers
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