Proceedings of the Royal Society B: Biological Sciences
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A role for iron and oxygen chemistry in preserving soft tissues, cells and molecules from deep time

Mary H. Schweitzer

Mary H. Schweitzer

Marine, Earth, and Atmospheric Sciences, North Carolina State University, Campus Box 8208, Raleigh, NC 27695, USA

North Carolina Museum of Natural Sciences, 11 West Jones Street, Raleigh, NC 27601, USA

[email protected]

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Wenxia Zheng

Wenxia Zheng

Marine, Earth, and Atmospheric Sciences, North Carolina State University, Campus Box 8208, Raleigh, NC 27695, USA

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Timothy P. Cleland

Timothy P. Cleland

Marine, Earth, and Atmospheric Sciences, North Carolina State University, Campus Box 8208, Raleigh, NC 27695, USA

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Mark B. Goodwin

Mark B. Goodwin

Museum of Paleontology, University of California, Berkeley, CA 94720, USA

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Elizabeth Boatman

Elizabeth Boatman

Department of Material Sciences and Engineering, University of California, Berkeley, CA 94720, USA

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Elizabeth Theil

Elizabeth Theil

CHORI (Children's Hospital Oakland Research Institute), 5700 Martin Luther King, Jr. Way, Oakland, CA 94609, USA

Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695-7622, USA

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Matthew A. Marcus

Matthew A. Marcus

Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA

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Sirine C. Fakra

Sirine C. Fakra

Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA

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    The persistence of original soft tissues in Mesozoic fossil bone is not explained by current chemical degradation models. We identified iron particles (goethite-αFeO(OH)) associated with soft tissues recovered from two Mesozoic dinosaurs, using transmission electron microscopy, electron energy loss spectroscopy, micro-X-ray diffraction and Fe micro-X-ray absorption near-edge structure. Iron chelators increased fossil tissue immunoreactivity to multiple antibodies dramatically, suggesting a role for iron in both preserving and masking proteins in fossil tissues. Haemoglobin (HB) increased tissue stability more than 200-fold, from approximately 3 days to more than two years at room temperature (25°C) in an ostrich blood vessel model developed to test post-mortem ‘tissue fixation’ by cross-linking or peroxidation. HB-induced solution hypoxia coupled with iron chelation enhances preservation as follows: HB + O2 > HB − O2 > −O2 ≫ +O2. The well-known O2/haeme interactions in the chemistry of life, such as respiration and bioenergetics, are complemented by O2/haeme interactions in the preservation of fossil soft tissues.

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