Article

A role for iron and oxygen chemistry in preserving soft tissues, cells and molecules from deep time

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, Museum of Paleontology, University of California, , Berkeley, CA 94720, USA, Department of Material Sciences and Engineering, University of California, , Berkeley, CA 94720, USA, 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, Advanced Light Source, Lawrence Berkeley National Laboratory, , Berkeley, CA 94720, USA.
Proceedings of the Royal Society B: Biological Sciences (Impact Factor: 5.05). 01/2014; 281(1775):20132741. DOI: 10.1098/rspb.2013.2741
Source: PubMed

ABSTRACT

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.

    • "Even if the best peptides to use for degradation assessment can be reliably predicted in advance from a closely related species, they may not always be preserved in a given fossil, or may not be recovered in analysis even when they are preserved. [28] Furthermore, it is unknown how changes to the sequence and 3D structure of proteins by diagenetic modifications, such as formation of advanced glycation end products (AGEs) [29] or inclusion of diagenetic iron on the proteins, [30] may further alter deamidation rates, potentially arresting this process while preserving peptides into geologic time and resulting in extreme deviations from 'expected' glutamine deamidation levels. Additional factors may further complicate efforts to establish a reliable relationship between age and deamidation. "
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