Microbial Dysbiosis in Colorectal Cancer (CRC) Patients

The composition of the human intestinal microbiota is linked to health status. The aim was to analyze the microbiota of normal and colon cancer patients in order to establish cancer-related dysbiosis

Paleomagnetic study of juvenile basaltic-andesite clasts from Andean pyroclastic density current deposits

Additional paleomagnetic data are necessary to improve geomagnetic models of secular variation during the Holocene, especially from the southern hemisphere. In most of the Andean volcanoes from Ecuador to the Chilean central volcanic zone, very well dated lava flows are rare. In contrast, andesitic to basaltic pyroclastic density current (PDC) deposits commonly contain charcoal, facilitating their age determination with C-14. In this study we present the magnetic properties and the paleomagnetic results obtained from three PDC deposits of basaltic to andesitic composition. One is the 2006 PDC deposit from the Ecuadorian Tungurahua volcano and the two others are well-dated PDC deposits from Chilean volcanoes Osorno and Villarica. Although most paleomagnetic studies in pyroclastic rocks deal with the estimation of emplacement temperatures from bulk deposits or accessory and accidental (non-juvenile) clasts, we show that juvenile clasts embedded in PDC deposits provide well-grouped paleomagnetic directions indicating post-emplacement in situ cooling below Curie points. Moreover, the rapid cooling of the juvenile clasts yields an abundance of single domain titanomagnetite grains providing low unblocking temperatures and a reliable material for paleointensity determination

Quantitative proteomic analysis exploring progression of colorectal cancer: Modulation of the serpin family

International audienceColorectal cancer (CRC) remains a major cause of cancer related-death in developed countries. The mortality risk is correlated with the stage of CRC determined at the primary diagnosis and early diagnosis is associated with enhanced survival rate. Currently, only faecal occult blood tests are used to screen for CRC. Consequently, there is an incentive to identify specific markers of CRC. We used quantitative proteomic analysis of serum samples to characterize protein profiles in adenoma, CRC and healthy control samples. We identified 89 distinct proteins modulated between normal, colorectal adenoma and carcinoma patients. This list emphasizes proteins involved in enzyme regulator activities and in particular the serpin family. In serum samples, protein profiles of three members of the serpin family (SERPINA1, SERPINA3 and SERPINC1) were confirmed by ELISA assays. We obtained sensitivity/specificity values of 95%/95% for both SERPINA1 and SERPINC1, and 95%/55% for SERPINA3. This study supports the idea that serum proteins can discriminate adenoma and CRC patients from unaffected patients and reveals a panel of regulated proteins that might be useful for selecting patients for colonoscopy. By evaluating SERPINA1, SERPINA3 and SERPINC1, we highlight the potential role of the serpin family during the development and progression of CRC

Glass Strewnfield Produced by Dry Vegetation Fires Rather than Airburst: A Case Study from Atacama

International audienceWe described in [1] extended occurrences of unusual silicate glass surface layers from the Atacama Desert(Chile). These glasses, found near the town of Pica at four localities separated by up to 70 km, are neither fulgurites,nor volcanic glasses, nor metallurgical slags related to anthropic activity, but show close similarities to other glassesthat have been previously attributed to large airbursts created by meteoroids entering the Earth’s atmosphere. Theglasses are restricted to specific Late Pleistocene terrains: paleo-wetlands and soils rich in organic matter with SiO2-rich plant remains, salts and carbonates. 14C dating and paleomagnetic data indicate that the glasses were formedduring at least two distinct periods in the 12 to 15 ka interval. This rules out the hypothesis of a single large airburstas the cause of surface melting. Instead, burning of organic-rich soils in dried-out grassy wetlands during climateoscillations between wet and dry periods can account for the formation of the Pica glasses.The reducing combustion condition produced iron sulphides, phosphides, carbides and metal droplets in theglass; these are usually taken as evidence for ET contamination, but no trace of Ni or other highly siderophile elements(e.g. Ir, Pt) were detected. Plant imprints are numerous in the Pica glass, as observed in the Dakhleh (Egypt),Pampa (Argentina) and Edowie (Australia) glasses of presumed impact origin [2-4]. As for Pica, the glass distributionappears restricted to the paleohumid depressions in both Edowie and Dakhleh cases. In case of an airburst thistopographic control cannot be explained. We therefore propose to reevaluate previously published evidence for glassstrewnfields attributed to airbursts [2-5] in the light of the Pica glass study

Glass Strewnfield Produced by Dry Vegetation Fires Rather than Airburst: A Case Study from Atacama

International audienceWe described in [1] extended occurrences of unusual silicate glass surface layers from the Atacama Desert(Chile). These glasses, found near the town of Pica at four localities separated by up to 70 km, are neither fulgurites,nor volcanic glasses, nor metallurgical slags related to anthropic activity, but show close similarities to other glassesthat have been previously attributed to large airbursts created by meteoroids entering the Earth’s atmosphere. Theglasses are restricted to specific Late Pleistocene terrains: paleo-wetlands and soils rich in organic matter with SiO2-rich plant remains, salts and carbonates. 14C dating and paleomagnetic data indicate that the glasses were formedduring at least two distinct periods in the 12 to 15 ka interval. This rules out the hypothesis of a single large airburstas the cause of surface melting. Instead, burning of organic-rich soils in dried-out grassy wetlands during climateoscillations between wet and dry periods can account for the formation of the Pica glasses.The reducing combustion condition produced iron sulphides, phosphides, carbides and metal droplets in theglass; these are usually taken as evidence for ET contamination, but no trace of Ni or other highly siderophile elements(e.g. Ir, Pt) were detected. Plant imprints are numerous in the Pica glass, as observed in the Dakhleh (Egypt),Pampa (Argentina) and Edowie (Australia) glasses of presumed impact origin [2-4]. As for Pica, the glass distributionappears restricted to the paleohumid depressions in both Edowie and Dakhleh cases. In case of an airburst thistopographic control cannot be explained. We therefore propose to reevaluate previously published evidence for glassstrewnfields attributed to airbursts [2-5] in the light of the Pica glass study

Positive feedback between p53 and TRF2 during telomere-damage signalling and cellular senescence

The telomere-capping complex (shelterin) protects functional telomeres from initiating unwanted DNA damage response. Uncapped telomeres at the end of cellular replicative lifespan lose this protective mechanism and trigger DNA damage signaling to activate p53 and thereby induce replicative senescence. Here we identify a signaling pathway involving p53, Siah-1, a p53-inducible E3 ubiquitin ligase, and TRF2, a component of the shelterin complex. Endogenous Siah-1 and TRF2 were up- and down-regulated, respectively, at replicative senescence with activated p53. A series of experimental manipulations of p53 showed that p53 induced Siah-1 and repressed TRF2 protein levels. The p53-dependent ubiquitination and proteasomal degradation of TRF2 were attributed to the E3 ligase activity of Siah-1. Siah-1 knockdown stabilized TRF2 and delayed the onset of cellular replicative senescence, suggesting the role of Siah-1 and TRF2 in p53-regulated senescence. This study reveals that p53, a downstream effector of the telomere-initiated damage signaling, also functions upstream of the shelterin complex