An Integrated Approach to the Taxonomic Identification of Prehistoric Shell Ornaments

Shell beads appear to have been one of the earliest examples of personal adornments. Marine shells identified far from the shore evidence long-distance transport and imply networks of exchange and negotiation. However, worked beads lose taxonomic clues to identification, and this may be compounded by taphonomic alteration. Consequently, the significance of this key early artefact may be underestimated. We report the use of bulk amino acid composition of the stable intra-crystalline proteins preserved in shell biominerals and the application of pattern recognition methods to a large dataset (777 samples) to demonstrate that taxonomic identification can be achieved at genus level. Amino acid analyses are fast (<2 hours per sample) and micro-destructive (sample size <2 mg). Their integration with non-destructive techniques provides a valuable and affordable tool, which can be used by archaeologists and museum curators to gain insight into early exploitation of natural resources by humans. Here we combine amino acid analyses, macro- and microstructural observations (by light microscopy and scanning electron microscopy) and Raman spectroscopy to try to identify the raw material used for beads discovered at the Early Bronze Age site of Great Cornard (UK). Our results show that at least two shell taxa were used and we hypothesise that these were sourced locally

Long-term resilience of late holocene coastal subsistence system in Southeastern South america.

Isotopic and molecular analysis on human, fauna and pottery remains can provide valuable new insights into the diets and subsistence practices of prehistoric populations. These are crucial to elucidate the resilience of social-ecological systems to cultural and environmental change. Bulk collagen carbon and nitrogen isotopic analysis of 82 human individuals from mid to late Holocene Brazilian archaeological sites (∼6,700 to ∼1,000 cal BP) reveal an adequate protein incorporation and, on the coast, the continuation in subsistence strategies based on the exploitation of aquatic resources despite the introduction of pottery and domesticated plant foods. These results are supported by carbon isotope analysis of single amino acid extracted from bone collagen. Chemical and isotopic analysis also shows that pottery technology was used to process marine foods and therefore assimilated into the existing subsistence strategy. Our multidisciplinary results demonstrate the resilient character of the coastal economy to cultural change during the late Holocene in southern Brazil

Shell sclerochronology and stable isotopes of the bivalve Anomalocardia flexuosa (Linnaeus, 1767) from southern Brazil: : implications for environmental and archaeological studies

We conduct the first stable isotopic and sclerochronological calibration of the bivalve Anomalocardia flexuosa (Linnaeus, 1767) in relation to environmental variables in a subtropical coastal area of southern Brazil. We investigate incremental shell growth patterns and δ18O and δ13C values of modern specimens collected alive from the Laguna Lagoonal System (LLS). As shells of Anomalocardia flexuosa are also the main components of pre-Columbian archaeological shell mounds and middens distributed along the Brazilian coastline, late Holocene archaeological specimens from a local shell mound (Cabeçuda) were selected to compare their stable carbon and oxygen isotopes with those of modern specimens. Shell growth increments, δ18O and δ13C values respond to a complex of environmental conditions, involving, for example, the effects of temperature and salinity. The isotopic information extracted from archaeological specimens from Cabeçuda shell midden in the LLS indirectly indicates that environmental conditions during the late Holocene were different from present day. In particular, intra-shell δ18O and δ13C values of archaeological shells reveal a stronger marine influence at 3 ka cal BP, which is in contrast to the seasonal freshwater/seawater balance that currently prevails at the LLS

Raman Spectroscopy Studies Of Multipotent Stromal Cells Differentiation For Bone Engineering Application

Raman spectroscopy (RS) is a label-free method based in the inelastic scattering of laser-light and can be used non-destructively to provide a biomolecular fingerprint of cells. Mesenchymal stromal cells (MSCs) are known for their heterogeneity and, unlike other stem cells, lack a unique marker, thus compromising their application in regenerative medicine. In this work, RS was investigated for its capacity to discriminate MSCs subpopulations, whilst still providing markers of their function. Four immortalised clonal MSC lines, which express the same surface proteins, have contrasting differentiation capacities and were not totally discriminated by global gene expression analyses, were investigated. Air-dried and live cell experiments were performed, as well as the induction of one cell line into ostegenesis and adipogenesis. Relative differences between proteins and DNA/RNA provided the discrimination of the undifferentiated MSCs towards their differentiation competence. Raman spectroscopy also showed clear progression of the adipogenic differentiation. During osteogenesis, the MSCs formed mineralised nodules with an architecture similar to native human bone. The RS investigation of these MSCs showed that the obtained Raman markers could be used to predict differentiation competence in undifferentiated cells and then, followed throughout osteogenesis

Classification results.

<p>Results of the classification performed using Learning Vector Quantization. Leave-one-out (L-O-O) classification was used for validation and the results show how the test samples were classified. Each row represents one of the 26 genera included in the analysis, as indicated on the left of the table together with the number of examples tested. The four-letter codes uniquely identify each genus (full names in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099839#pone-0099839-t001" target="_blank">Table 1</a>). The columns show the predicted genera. Numerical values are percentages so that the element in column <i>i</i> of row <i>j</i> shows the percentage of genus <i>j</i> that were classified as genus <i>i</i> and the main diagonal shows the percentage of each genus correctly classified. The dotted lines separate Bivalvia from Gastropoda and brackets above the predicted class names group genera within the same order. The grey-scale intensities are related to the numerical values with white corresponding to 100% and the darkest grey to 0% (for which no numerical value is given). Note that rounding may result in rows not summing to 100%.</p

Great Cornard bead 3682.

<p>(a) Photograph and (b) photomicrograph of the surface. The bulk of the bead is granular but this surface has the remnants of a thin layer of a whiter, more opaque material with a finely striated appearance.</p

PCA scores plots showing examples closest to the beads.

<p>Scores plots from principal components analysis showing only examples from genera with scores closest to the beads. Bead 3870 can be seen, clustered with <i>Unio</i> and <i>Antalis</i> examples on the left of the plots. Although <i>Pecten</i> examples overlap with <i>Nucella</i> and the other beads in the scores plot for the first two principal components (a), separation can be seen along the third component (b).</p

Great Cornard bead 3870 and <i>Antalis</i> sp.

<p>Photograph (a, b) and scanning electron microscopy images (c, d) of bead 3870 (a, c) and <i>Antalis</i> sp. (b, d).</p

Dendogram for the genera most similar to the beads.

<p>Dendogram showing the results of hierarchical cluster analysis on the amino acid signatures for the genera most similar to the Great Cornard beads.</p

Coefficient of similarity distributions.

<p>The distributions of CS values for correct (solid line) and incorrect (dashed line) classifications.</p