Potentials and limitations for the identification of outdoor dung plasters in humid tropical environment: a geo-ethnoarchaeological case study from South India

© 2018, The Author(s). Dung has been an important material used by humans since at least the early Neolithic Period. It accumulated within domesticated animal enclosures and it was used as fuel and fertiliser as well as construction material. While the formers were studied in details, to date, the use of dung as a construction material received less attention. Here, we present a geo-ethnoarchaeological pilot study aimed at understanding the archaeological formation processes of outdoor dung-plastered floors and the possibility to identify dung markers. We studied two house terrace in a rural village from a humid tropical environment in South India (Western Ghats). Sediment samples were collected from the plastered terrace surfaces, the terraces embankment and from forest soil controls. Multi-proxy analysis of the samples included infrared spectroscopy, phytolith and dung spherulite quantification, loss on ignition, elemental analysis and micromorphological analysis. The plastering of the floors was made by mixing a quantity of dung with water and by spreading the slurry unevenly across the terrace. This result in formation of a 0.1- to 0.5-mm-thick dung crust that the analyses showed to be rich in humified organics but with very low concentrations of phytoliths and dung spherulites. The careless spreading of the dung slurry, however, resulted in localised deposition of dung lumps that displayed relatively high concentrations of phytoliths, dung spherulites, organic matter, phosphorus and strontium. The generally low preservation of dung markers seems to be related to pre- and post-depositional processes. Forest arboreal plants are low phytoliths producer, having therefore little input of these siliceous bodies in the animal faeces. Post depositional processes included trampling, sweeping and water runoff that caused severe mechanical weathering, resulting in the heavy decay of the dung crust and the removal of dung residues from the terrace surfaces. In addition, the acidic conditions of a humid tropical environment likely promoted the complete dissolution of dung spherulites. This study provides new data and insights on the potentials and limitations of dung identification in outdoor settings in humid tropical environments. We suggest possible directions for advancing the study of archaeological dung used as construction materials

Hepatitis C virus leaves an epigenetic signature post cure of infection by direct-acting antivirals

The increasing worldwide prevalence of Hepatocellular carcinoma (HCC), characterized by resistance to conventional chemotherapy, poor prognosis and eventually mortality, place it as a prime target for new modes of prevention and treatment. Hepatitis C Virus (HCV) is the predominant risk factor for HCC in the US and Europe. Multiple epidemiological studies showed that sustained virological responses (SVR) following treatment with the powerful direct acting antivirals (DAAs), which have replaced interferon-based regimes, do not eliminate tumor development. We aimed to identify an HCV-specific pathogenic mechanism that persists post SVR following DAAs treatment. We demonstrate that HCV infection induces genome-wide epigenetic changes by performing chromatin immunoprecipitation followed by next-generation sequencing (ChIP-seq) for histone post-translational modifications that are epigenetic markers for active and repressed chromatin. The changes in histone modifications correlate with reprogramed host gene expression and alter signaling pathways known to be associated with HCV life cycle and HCC. These epigenetic alterations require the presence of HCV RNA or/and expression of the viral proteins in the cells. Importantly, the epigenetic changes induced following infection persist as an "epigenetic signature" after virus eradication by DAAs treatment, as detected using in vitro HCV infection models. These observations led to the identification of an 8 gene signature that is associated with HCC development and demonstrate persistent epigenetic alterations in HCV infected and post SVR liver biopsy samples. The epigenetic signature was reverted in vitro by drugs that inhibit epigenetic modifying enzyme and by the EGFR inhibitor, Erlotinib. This epigenetic "scarring" of the genome, persisting following HCV eradication, suggest a novel mechanism for the persistent pathogenesis of HCV after its eradication by DAAs. Our study offers new avenues for prevention of the persistent oncogenic effects of chronic hepatitis infections using specific drugs to revert the epigenetic changes to the genome