205 research outputs found

    The Role of Carbonate Factories and Sea Water Chemistry on Basin-Wide Ramp to High-Relief Carbonate Platform Evolution: Triassic, Nanpanjiang Basin, South China

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    The end-Permian extinction and its aftermath altered carbonate factories globally for millions of years, but its impact on platform geometries remains poorly understood. Here, the evolution in architecture and composition of two exceptionally exposed platforms in the Nanpanjiang Basin are constrained and compared with geochemical proxies to evaluate controls on platform geometries. Geochemical proxies indicate elevated siliciclastic and nutrient fluxes in the basal Triassic, at the Induan—Olenekian boundary and in the uppermost Olenekian. Cerium/Ce* shifts from high Ce/Ce* values and a lack of Ce anomaly indicating anoxia during the Lower Triassic to a negative Ce anomaly indicating oxygenation in the latest Olenekian and Anisian. Uranium and Mo depletion represents widespread anoxia in the world\u27s oceans in the Early Triassic with progressive oxygenation in the Anisian. Carbonate factories shifted from skeletal in the Late Permian to abiotic and microbial in the Early Triassic before returning to skeletal systems in the Middle Triassic, Anisian coincident with declining anoxia. Margin facies shifted to oolitic grainstone in the Early Triassic with development of giant ooids and extensive marine cements. Anisian margins, in contrast, are boundstone with a diverse skeletal component. The shift in platform architecture from ramp to steep, high-relief, flat-topped profiles is decoupled from carbonate compositions having occurred in the Olenekian prior to the onset of basin oxygenation and biotic stabilisation of the margins. A basin-wide synchronous shift from ramp to high-relief platforms points to a combination of high subsidence rate and basin starvation coupled with high rates of abiotic and microbial carbonate accumulation and marine cement stabilisation of oolitic margins as the primary causes for margin up-building. High sea water carbonate saturation resulting from a lack of skeletal sinks for precipitation, and basin anoxia promoting an expanded depth of carbonate supersaturation, probably contributed to marine cement stabilisation of margins that stimulated the shift from ramp to high-relief platform architecture

    Earliest Triassic microbialites in the South China Block and other areas; controls on their growth and distribution

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    Earliest Triassic microbialites (ETMs) and inorganic carbonate crystal fans formed after the end-Permian mass extinction (ca. 251.4 Ma) within the basal Triassic Hindeodus parvus conodont zone. ETMs are distinguished from rarer, and more regional, subsequent Triassic microbialites. Large differences in ETMs between northern and southern areas of the South China block suggest geographic provinces, and ETMs are most abundant throughout the equatorial Tethys Ocean with further geographic variation. ETMs occur in shallow-marine shelves in a superanoxic stratified ocean and form the only widespread Phanerozoic microbialites with structures similar to those of the Cambro-Ordovician, and briefly after the latest Ordovician, Late Silurian and Late Devonian extinctions. ETMs disappeared long before the mid-Triassic biotic recovery, but it is not clear why, if they are interpreted as disaster taxa. In general, ETM occurrence suggests that microbially mediated calcification occurred where upwelled carbonate-rich anoxic waters mixed with warm aerated surface waters, forming regional dysoxia, so that extreme carbonate supersaturation and dysoxic conditions were both required for their growth. Long-term oceanic and atmospheric changes may have contributed to a trigger for ETM formation. In equatorial western Pangea, the earliest microbialites are late Early Triassic, but it is possible that ETMs could exist in western Pangea, if well-preserved earliest Triassic facies are discovered in future work

    Real-Time Cleaning and Refinement of Facial Animation Signals

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    With the increasing demand for real-time animated 3D content in the entertainment industry and beyond, performance-based animation has garnered interest among both academic and industrial communities. While recent solutions for motion-capture animation have achieved impressive results, handmade post-processing is often needed, as the generated animations often contain artifacts. Existing real-time motion capture solutions have opted for standard signal processing methods to strengthen temporal coherence of the resulting animations and remove inaccuracies. While these methods produce smooth results, they inherently filter-out part of the dynamics of facial motion, such as high frequency transient movements. In this work, we propose a real-time animation refining system that preserves -- or even restores -- the natural dynamics of facial motions. To do so, we leverage an off-the-shelf recurrent neural network architecture that learns proper facial dynamics patterns on clean animation data. We parametrize our system using the temporal derivatives of the signal, enabling our network to process animations at any framerate. Qualitative results show that our system is able to retrieve natural motion signals from noisy or degraded input animation.Comment: ICGSP 2020: Proceedings of the 2020 The 4th International Conference on Graphics and Signal Processin

    Prolyl‐4‐hydroxylases 2 and 3 control erythropoietin production in renin‐expressing cells of mouse kidneys

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    Activation of the hypoxia-signalling pathway induced by deletion of the ubiquitin-ligase von Hippel–Lindau protein causes an endocrine shift of renin-producing cells to erythropoietin (EPO)-expressing cells. However, the underlying mechanisms have not yet been investigated. Since oxygen-regulated stability of hypoxia-inducible transcription factors relevant for EPO expression is dependent on the activity of prolyl-4-hydroxylases (PHD) 2 and 3, this study aimed to determine the relevance of different PHD isoforms for the EPO expression in renin-producing cells in vivo. For this purpose, mice with inducible renin cell-specific deletions of different PHD isoforms were analysed. Our study shows that there are two subgroups of renal renin-expressing cells, juxtaglomerular renin+ cells and platelet-derived growth factor receptor-β+ interstitial renin+ cells. These interstitial renin+ cells belong to the cell pool of native EPO-producing cells and are able to express EPO and renin in parallel. In contrast, co-deletion of PHD2 and PHD3, but not PHD2 deletion alone, induces EPO expression in juxtaglomerular and hyperplastic renin+ cells and downregulates renin expression. A strong basal PHD3 expression in juxtaglomerular renin+ cells seems to prevent the hypoxia-inducible transcription factor-2-dependent phenotype shift into EPO cells. In summary, PHDs seem important for the stabilization of the juxtaglomerular renin cell phenotype. Moreover, these findings reveal tubulointerstitial cells as a novel site of renal renin expression and suggest a high endocrine plasticity of these cells. Our data concerning the distinct expression patterns and functions of PHD2 and PHD3 provide new insights into the regulation of renin-producing cells and highlight the need for selective PHD inhibitors

    Transcriptional Changes Common to Human Cocaine, Cannabis and Phencyclidine Abuse

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    A major goal of drug abuse research is to identify and understand drug-induced changes in brain function that are common to many or all drugs of abuse. As these may underlie drug dependence and addiction, the purpose of the present study was to examine if different drugs of abuse effect changes in gene expression that converge in common molecular pathways. Microarray analysis was employed to assay brain gene expression in postmortem anterior prefrontal cortex (aPFC) from 42 human cocaine, cannabis and/or phencyclidine abuse cases and 30 control cases, which were characterized by toxicology and drug abuse history. Common transcriptional changes were demonstrated for a majority of drug abuse cases (N = 34), representing a number of consistently changed functional classes: Calmodulin-related transcripts (CALM1, CALM2, CAMK2B) were decreased, while transcripts related to cholesterol biosynthesis and trafficking (FDFT1, APOL2, SCARB1), and Golgi/endoplasmic reticulum (ER) functions (SEMA3B, GCC1) were all increased. Quantitative PCR validated decreases in calmodulin 2 (CALM2) mRNA and increases in apolipoprotein L, 2 (APOL2) and semaphorin 3B (SEMA3B) mRNA for individual cases. A comparison between control cases with and without cardiovascular disease and elevated body mass index indicated that these changes were not due to general cellular and metabolic stress, but appeared specific to the use of drugs. Therefore, humans who abused cocaine, cannabis and/or phencyclidine share a decrease in transcription of calmodulin-related genes and increased transcription related to lipid/cholesterol and Golgi/ER function. These changes represent common molecular features of drug abuse, which may underlie changes in synaptic function and plasticity that could have important ramifications for decision-making capabilities in drug abusers

    Altered Gene Expression in Pulmonary Tissue of Tryptophan Hydroxylase-1 Knockout Mice: Implications for Pulmonary Arterial Hypertension

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    The use of fenfluramines can increase the risk of developing pulmonary arterial hypertension (PAH) in humans, but the mechanisms responsible are unresolved. A recent study reported that female mice lacking the gene for tryptophan hydroxylase-1 (Tph1(−/−) mice) were protected from PAH caused by chronic dexfenfluramine, suggesting a pivotal role for peripheral serotonin (5-HT) in the disease process. Here we tested two alternative hypotheses which might explain the lack of dexfenfluramine-induced PAH in Tph1(−/−) mice. We postulated that: 1) Tph1(−/−) mice express lower levels of pulmonary 5-HT transporter (SERT) when compared to wild-type controls, and 2) Tph1(−/−) mice display adaptive changes in the expression of non-serotonergic pulmonary genes which are implicated in PAH. SERT was measured using radioligand binding methods, whereas gene expression was measured using microarrays followed by quantitative real time PCR (qRT-PCR). Contrary to our first hypothesis, the number of pulmonary SERT sites was modestly up-regulated in female Tph1(−/−) mice. The expression of 51 distinct genes was significantly altered in the lungs of female Tph1(−/−) mice. Consistent with our second hypothesis, qRT-PCR confirmed that at least three genes implicated in the pathogenesis of PAH were markedly up-regulated: Has2, Hapln3 and Retlna. The finding that female Tph1(−/−) mice are protected from dexfenfluramine-induced PAH could be related to compensatory changes in pulmonary gene expression, in addition to reductions in peripheral 5-HT. These observations emphasize the intrinsic limitation of interpreting data from studies conducted in transgenic mice that are not fully characterized

    Geological fate of seafloor massive sulphides at the TAG hydrothermal field (Mid-Atlantic Ridge)

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    Highlights • Generic geological model of hydrothermally extinct seafloor massive sulphide. • Sub-surface characterisation by combined drilling and geophysics. • New resource estimate for slow-spreading mid-ocean ridges. • Holistic approach to seafloor mineral deposits assessment. Abstract Deep-sea mineral deposits potentially represent vast metal resources that could make a major contribution to future global raw material supply. Increasing demand for these metals, many of which are required to enable a low-carbon and high-technology society and to relieve pressure on land-based resources, may result in deep sea mining within the next decade. Seafloor massive sulphide (SMS) deposits, containing abundant copper, zinc, gold and silver, have been the subject of recent and ongoing commercial interest. Although many seafloor hydrothermally systems have been studied, inactive SMS deposits are likely to more accessible to future mining and far more abundant, but are often obscured by pelagic sediment and hence difficult to locate. Furthermore, SMS deposits are three dimensional. Yet, to date, very few have been explored or sampled below the seafloor. Here, we describe the most comprehensive study to date of hydrothermally extinct seafloor massive sulphide deposits formed at a slow spreading ridge. Our approach involved two research cruises in the summer of 2016 to the TAG hydrothermal field at 26°N on the Mid-Atlantic Ridge. These expeditions mapped a number of hydrothermally extinct SMS deposits using an autonomous underwater vehicle and remotely operated vehicle, acquired a combination of geophysical data including sub-seafloor seismic reflection and refraction data from 25 ocean bottom instruments, and recovered core using a sub-seafloor drilling rig. Together, these results that have allowed us to construct a new generic model for extinct seafloor massive sulphide deposits that indicate the presence of up to five times more massive sulphide at and below the seafloor than was previously thought

    Amitriptyline-Mediated Cognitive Enhancement in Aged 3×Tg Alzheimer's Disease Mice Is Associated with Neurogenesis and Neurotrophic Activity

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    Approximately 35 million people worldwide suffer from Alzheimer's disease (AD). Existing therapeutics, while moderately effective, are currently unable to stem the widespread rise in AD prevalence. AD is associated with an increase in amyloid beta (Aβ) oligomers and hyperphosphorylated tau, along with cognitive impairment and neurodegeneration. Several antidepressants have shown promise in improving cognition and alleviating oxidative stress in AD but have failed as long-term therapeutics. In this study, amitriptyline, an FDA-approved tricyclic antidepressant, was administered orally to aged and cognitively impaired transgenic AD mice (3×TgAD). After amitriptyline treatment, cognitive behavior testing demonstrated that there was a significant improvement in both long- and short-term memory retention. Amitriptyline treatment also caused a significant potentiation of non-toxic Aβ monomer with a concomitant decrease in cytotoxic dimer Aβ load, compared to vehicle-treated 3×TgAD controls. In addition, amitriptyline administration caused a significant increase in dentate gyrus neurogenesis as well as increases in expression of neurosynaptic marker proteins. Amitriptyline treatment resulted in increases in hippocampal brain-derived neurotrophic factor protein as well as increased tyrosine phosphorylation of its cognate receptor (TrkB). These results indicate that amitriptyline has significant beneficial actions in aged and damaged AD brains and that it shows promise as a tolerable novel therapeutic for the treatment of AD

    Synchronous retreat of Thwaites and Pine Island glaciers in response to external forcings in the presatellite era

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    Today, relatively warm Circumpolar Deep Water is melting Thwaites Glacier at the base of its ice shelf and at the grounding zone, contributing to significant ice retreat. Accelerating ice loss has been observed since the 1970s; however, it is unclear when this phase of significant melting initiated. We analyzed the marine sedimentary record to reconstruct Thwaites Glacier’s history from the early Holocene to present. Marine geophysical surveys were carried out along the floating ice-shelf margin to identify core locations from various geomorphic settings. We use sedimentological data and physical properties to define sedimentary facies at seven core sites. Glaciomarine sediment deposits reveal that the grounded ice in the Amundsen Sea Embayment had already retreated to within ~45 km of the modern grounding zone prior to ca. 9,400 y ago. Sediments deposited within the past 100+ y record abrupt changes in environmental conditions. On seafloor highs, these shifts document ice-shelf thinning initiating at least as early as the 1940s. Sediments recovered from deep basins reflect a transition from ice proximal to slightly more distal conditions, suggesting ongoing grounding-zone retreat since the 1950s. The timing of ice-shelf unpinning from the seafloor for Thwaites Glacier coincides with similar records from neighboring Pine Island Glacier. Our work provides robust new evidence that glacier retreat in the Amundsen Sea was initiated in the mid-twentieth century, likely associated with climate variability

    Deactylase inhibition in myeloproliferative neoplasms

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    Myeloproliferative neoplasms (MPN) are clonal haemopoietic progenitor cell disorders characterized by the proliferation of one or more of the haemopoietic lineages (myeloid, erythroid and/or megakaryocytic). The MPNs include eight haematological disorders: chronic myelogenous leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET), primary myelofibrosis (PMF), systemic mastocytosis (SM), chronic eosinophilic leukemia, not otherwise specified (CEL, NOS), chronic neutrophilic leukemia (CNL), and unclassifiable MPN (MPN, U). Therapeutic interventions for MPNs include the use of tyrosine kinase inhibitors (TKIs) for BCR-ABL1+ CML and JAK2 inhibitors for PV, ET and PMF. Histone deacetylase inhibitors (HDACi) are a novel class of drugs capable of altering the acetylation status of both histone and non-histone proteins, thereby affecting a repertoire of cellular functions in neoplastic cells including proliferation, differentiation, immune responses, angiogenesis and survival. Preliminary studies indicate that HDACi when used in combination with tyrosine kinase or JAK2 inhibitors may overcome resistance to the latter agents and enhance the pro-apoptotic effects on MPN cells. This review provides a review of pre-clinical and clinical studies that have explored the use of HDACi as potential therapeutics for MPNs
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