title: A role for iron and oxygen chemistry in preserving soft tissues, cells and molecules from deep time.
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.
authors.affiliation: 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.
authors.forename: Mary H
authors.initials: MH
authors.lastname: Schweitzer
authors.forename: Wenxia
authors.initials: W
authors.lastname: Zheng
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Cleland
authors.forename: Mark B
authors.initials: MB
authors.lastname: Goodwin
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Boatman
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Theil
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Marcus
authors.forename: Sirine C
authors.initials: SC
authors.lastname: Fakra
mesh_terms: D000818:Animals; D025061:Dinosaurs / Q000033:anatomy & histology; D005580:Fossils; D007501:Iron / Q000032:analysis / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D010100:Oxygen / Q000737:chemistry*; D020310:Struthioniformes / Q000097:blood
chemical_list: D007501:Iron; D010100:Oxygen
keywords: Fenton chemistry; goethite; haemoglobin; iron; protein cross-linking; soft tissue preservation