Project description:Studies of ancient DNA have revolutionized our understanding of extinct organisms, but thus far the maximum estimated age of sequenced DNA is two million years. However, evidence for endogenous biomolecules, including proteins, lipids, and pigments have been found in much older fossils, dating to up to 195 million years. Amino acid sequence data consistent with ancient, endogenous biomolecules have been derived from specimens of the theropod Tyrannosaurus rex (MOR 1125) and the hadrosaur Brachylophosaurus canadensis (MOR 2598). Histochemical and immunological studies also identified a molecule consistent with DNA in these two ancient specimens, localized to a single point within preserved osteocytes. Here we report the sequencing and analysis of DNA extracted from osteocytes and blood vessels of T. rex and B. canadensis, liberated after demineralization of dense cortical bone. Usable sequence reads were obtained at a low recovery rate. After the removal of high-quality reads that mapped to the human genome, the remaining reads were highly fragmented, with similarities to multiple animal species including reptilian and avian genomes. Our findings support the hypothesis that DNA and histone signal from imaging, mass spectrometry, and DNA sequencing of dinosaur osteocytes are endogenously preserved biomolecules.
Project description:Ancient DNA (aDNA) sequencing has enabled reconstruction of speciation, migration, and admixture events for extinct taxa. Outside the permafrost, however, irreversible aDNA post-mortem degradation has so far limited aDNA recovery to the past ~0.5 million years (Ma). Contrarily, multiple analyses suggested the presence of protein residues in Cretaceous fossil remains. Similarly, tandem mass spectrometry (MS) allowed sequencing ~1.5 million year (Ma) old collagen type I (COL1), though with limited phylogenetic use. In the absence of molecular evidence, the speciation of several Early and Middle Pleistocene extinct species remain contentious. In this study, we address the phylogenetic relationships of the Eurasian Pleistocene Rhinocerotidae using a ~1.77 Ma old dental enamel proteome of a Stephanorhinus specimen from the Dmanisi archaeological site in Georgia (South Caucasus). Molecular phylogenetic analyses place the Dmanisi Stephanorhinus as a sister group to the woolly (Coelodonta antiquitatis) and Merck’s rhinoceros (S. kirchbergensis) clade. We show that Coelodonta evolved from an early Stephanorhinus lineage and that the latter includes at least two distinct evolutionary lines. As such, the genus Stephanorhinus is currently paraphyletic and requires systematic revision. We demonstrate that Early Pleistocene dental enamel proteome sequencing overcomes the limits of ancient collagen- and aDNA-based phylogenetic inference. It also provides additional information about the sex and taxonomic assignment of the specimens analysed. Dental enamel, the hardest tissue in vertebrates, is highly abundant in the fossil record. Our findings reveal that palaeoproteomic investigation of this material can push biomolecular investigation further back into the Early Pleistocene.
Project description:Characterization of Middle Pleistocene rhinoceros proteins and the phylogenetic relationships between extinct and extanct rhinoceros was investigated by obtaining ancient protein data for two extinct rhinoceros genera (Coelodonta antiquitatis and Stephanorhinus sp.).
Project description:The ancient preserved molecules in bones offer the opportunity to gain a better knowledge on the biological past. In recent years, bones proteomics has become an attractive method to study extinct species and phylogenetic evolution as an alternative to DNA analysis which is limited by DNA amplification present in ancient samples and its contamination. The analysis of fossils must consume a low quantity of material to avoid damaging the samples. Another difficulty is the absence of genomic data for most of the extinct species. This study applied a proteomic methodology to mammalian bones of 130,000 / 120,000 years old from the last Chibanian and the earlier Upper Pleistocene site of Waziers (France). The presence of lithic artefacts and the traces of butchery observed on the bones indicate the presence of Neanderthal Man on this site. Starting from 5 milligram samples, our results show that most detected peptides match collagen I alpha 1 and alpha 2 proteins with a sequence coverage up to 60 %. Using sequence homology with modern sequences, a biological classification was successfully achieved. Each bone taxonomic rank by proteomics was consistent with the existing osteomorphological studies and palaeoenvironmental and palaeodietary data.
Project description:Here we show the potential of proteins preserved in Pleistocene eggshell for addressing a longstanding controversy in human and evolution: the identity of the extinct bird that laid the eggs which were exploited by Australia’s first inhabitants. The eggs had been originally attributed to the iconic extinct flightless Genyornis newtoni, and subsequently dated to before 50 ±5 ka by Miller et al. (2016). This was taken to represent the extinction date for this endemic megafaunal species and thus implied a role of humans in its demise. A contrasting hypothesis, according to which the eggshell was laid by a large megapode (mound-builder), would therefore acquit humans of their responsibility in the extinction of Genyornis. Ancient protein sequences were reconstructed and used to assess the evolutionary proximity of the undetermined eggshell to extant birds, rejecting the megapode hypothesis. Ancient DNA could not be retrieved from these highly degraded samples, but morphometric data supported the attribution of the eggshell to Genyornis. When used in triangulation to address well-defined hypotheses, palaeoproteomics is a precious tool for reconstructing the evolutionary history of extinct and extant species. Here we show that the identification of Genyornis eggshell implies a more nuanced understanding of the modes of interactions between humans and their environment.
Project description:SepH was identified having a potential role in sporulation following ChIP-seq analysis that showed the sepH gene is under the control of the WhiA and WhiB transcription factors (Bush et al., 2013; Bush et al., 2016). Since SepH has a helix-turn-helix motif, this ChIP-Seq experiment was carried out to determine whether SepH specifically binds DNA and if so, where.