Project description:Genetic and limited palaeoanthropological data suggest that Denisovans, a sister group to Neanderthals, were once widely distributed in eastern Eurasia, likely stretching from high-latitude Siberia, to the high-altitude Tibetan Plateau, to the low-latitude subtropical regions of southeast Asia. This suggests that Denisovans were capable of adapting to a highly diverse range of environments, but archaeological evidence for this is currently limited. As a result, we know little about their behaviours, including subsistence strategies, across the vast areas they likely occupied. Here, we describe the late Middle to Late Pleistocene faunal assemblage from Baishiya Karst Cave on the Tibetan Plateau, where the Xiahe Denisovan mandible and Denisovan sedimentary mtDNA were found, by integrating proteomic screening into traditional zooarchaeological analysis. The results indicate that the faunal assemblage consists of a diverse range of animals, including megafauna, large mammals, small mammals and birds, but is dominated by medium-sized herbivores. Frequent cut marks and percussion traces on bone surfaces throughout the assemblage, even on carnivore bones, indicate that Denisovan activities in Baishiya Karst Cave from at least 190 to 30 thousand years are responsible for the fauna assemblage accumulation. Thorough utilization of acquired animal resources, even perhaps the fur, too, might have helped Denisovans to survive through the last two glacial-interglacial cycles on the cold high-altitude Tibetan Plateau. Our results shed new light on Denisovan behaviours and their adaptations to the diverse and fluctuated environments in the Middle and Late Pleistocene eastern Eurasia.
Project description:We characterize the TERRA transcriptome at normal and TRF2-depleted telomeres by RNA-seq and we demonstrate that TERRA upregulation is occurring at all transcribed telomeres upon depletion of TRF2. RNA-sequencing of HeLa mRNA, 4 samples: with or without TERRA enrichment by IP (respectively "IP" and "input"), with or without TFR-2 knock-down (respectively "_T" and "_EV").
Project description:Through an integration of genomic and proteomic approaches to advance understanding of long noncoding RNAs, we investigate the function of the telomeric transcript, TERRA. By identifying thousands of TERRA target sites in the mouse genome, we demonstrate that TERRA can bind both in cis to telomeres and in trans to genic targets. We then define a large network of interacting proteins, including epigenetic factors, telomeric proteins, and the RNA helicase, ATRX. TERRA and ATRX share hundreds of target genes and are functionally antagonistic at these loci: whereas TERRA activates, ATRX represses gene expression. At telomeres, TERRA competes with telomeric DNA for ATRX binding, suppresses ATRX localization, and ensures telomeric stability. Depleting TERRA increases telomerase activity and induces telomeric pathologies, including formation of telomere-induced DNA damage foci and loss or duplication of telomeric sequences. We conclude that TERRA functions as an epigenomic modulator in trans and as an essential regulator of telomeres in cis.
Project description:Glaciers are populated by a large number of microorganisms including bacteria, archaea and microeukaryotes. From an ecological point of view, three ecosystems can be differentiated in glaciers: the supraglacial ecosystem, the subglacial ecosystem and the englacial ecosystem. Several factors such as solar radiation, nutrient availability and water content greatly determine the diversity and abundance of microbial populations, the type of metabolism and the biogeochemical cycles. This huge diversity is threatened by climate change. This sampling place, Sarrios ice cave (Monte Perdido massif, Spanish Pyrenees) host one of the last permafrost deposits. Permafrost can provide us very worthy information about past climate and environmental conditions, therefore it should be studied as soon as possible due to the huge retreat that is already taking place. In order to study their metabolic potentials, samples of ice and permafrost were taken from an Antarctic glacier. The cells were harvested and their proteins were extracted and analyzed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI/TOF/TOF). Several proteins and enzymes were found that demonstrate the existence of cellular activity at subzero temperatures. In this way it is shown that the englacial microorganisms are not quiescent, but that they maintain an active metabolism and play an important role in the glacial microbial community.