Combining elemental and immunochemical analyses to characterize diagenetic alteration patterns in ancient skeletal remains

Abstract

Bones and teeth are biological archives, but their structure and composition are subjected to alteration overtime due to biological and chemical degradation postmortem, influenced by burial environment and conditions. Nevertheless, organic fraction preservation is mandatory for several archeometric analyses and applications. The mutual protection between biomineral and organic fractions in bones and teeth may lead to a limited diagenetic alteration, promoting a better conservation of the organic fraction. However, the correlation between elemental variations and the presence of organic materials (e.g., collagen) in the same specimen is still unclear. To fill this gap, chemiluminescent (CL) immunochemical imaging analysis has been applied for the first time for collagen localization. Then, Laser Ablation–Inductively Coupled Plasma–Mass Spectrometry (LA–ICP–MS) and CL imaging were combined to investigate the correlation between elemental (i.e., REE, U, Sr, Ba) and collagen distribution. Teeth and bones from various archeological contexts, chronological periods, and characterized by different collagen content were analyzed. Immunochemical analysis revealed a heterogeneous distribution of collagen, especially in highly degraded samples. Subsequently, LA–ICP–MS showed a correlation between the presence of uranium and rare earth elements and areas with low amount of collagen. The innovative integration between the two methods permitted to clarify the mutual relation between elemental variation and collagen preservation overtime, thus contributing to unravel the effects of diagenetic alteration in bones and teeth.

Soft-Tissue, Rare Earth Element, and Molecular Analyses of Dreadnoughtus schrani, an Exceptionally Complete Titanosaur from Argentina

“…However, following early diagenetic fossilization, the bones experienced negligible further chemical alteration. These findings support the hypotheses advanced by Trueman et al [ 101 ], Ullmann et al [ 123 ], and Gatti et al [ 129 ] that bones exhibiting low trace element uptake are favorable targets for paleomolecular analyses. Moving forward, we encourage the paleomolecular community to include more extensive geochemical analyses as part of their molecular testing routine, as such data will ultimately hold the key to unraveling the complex relationship between diagenesis and ‘exceptional’ preservation.…”

Spatial analysis of the ancient proteome of archeological teeth using mass spectrometry imaging

“…In humans, collagen type I takes the form of a triple helix, where two of the strands are contributed by collagen alpha‐1 and the third by collagen alpha‐2, and therefore as the two are part of the same larger molecule, their spatial patterns should be similar. Furthermore, the collagen distribution in teeth visualised using fluorescence and immunochemical chemiluminescence 12,23 also did not align well with our images, but it is not clear how comparable these methods are to MSI.…”

“…Variation in the preservation and distribution of proteins in archaeological material is a substantial challenge for the consistency and applicability of palaeoproteomics, with biological and diagenetic processes leading to differences in the abundance and presence of proteins between samples 8,12,13 . While there is a substantial body of work on protein diagenesis in archaeological bones and teeth, 14 our knowledge of the spatial distribution of proteins within these archaeological tissues remains limited.…”

“…11 Variation in the preservation and distribution of proteins in archaeological material is a substantial challenge for the consistency and applicability of palaeoproteomics, with biological and diagenetic processes leading to differences in the abundance and presence of proteins between samples. 8,12,13 While there is a substantial body of work on protein diagenesis in archaeological bones and teeth, 14 our knowledge of the spatial distribution of proteins within these archaeological tissues remains limited. Understanding this distribution would contribute to tackling several challenges in palaeoproteomics: the identification of specific target locations for sampling (and, as a consequence, minimising unnecessary damage), the interpretation of data from sequential sampling in dental tissue and the variable preservation of particular proteins in archaeological materials.…”

Reassociation of Skeletal Remains Using Laser-Induced Breakdown Spectroscopy

“…17,39 Trace elements such as strontium, barium, and aluminum are not known to be metabolically active. 40,41 Therefore, their presence may be correlated with levels of dietary intake or environmental exposure. It must also be noted that the phenomenon of diagenesis may play a role in determining the presence and distribution of chemical elements within the skeletal remains.…”