1,114 research outputs found

    Neither phylogenomic nor palaeontological data support a Palaeogene origin of placental mammals.

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    O'Leary et al. (O'Leary et al. 2013 Science 339, 662-667. (doi:10.1126/science.1229237)) performed a fossil-only dating analysis of mammals, concluding that the ancestor of placentals post-dated the Cretaceous-Palaeogene boundary, contradicting previous palaeontological and molecular studies that placed the ancestor in the Cretaceous. They incorrectly used fossil ages as species divergence times for crown groups, while in fact the former should merely form minimum-age bounds for the latter. Statistical analyses of the fossil record have shown that crown groups are significantly older than the oldest ingroup fossil, so that fossils do not directly reflect the true ages of clades. Here, we analyse a 20 million nucleotide genome-scale alignment in conjunction with a probabilistic interpretation of the fossil ages from O'Leary et al. Our combined analysis of fossils and molecules demonstrates that Placentalia originated in the Cretaceous.This work was financially supported by BBSRC grant no. BB/J009709/1

    Geoquímica das rochas granitóides da suíte intrusiva pedra pintada: norte do estado de Roraima

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    Selection of ligand peptides with the ability to detect antibodies in enzootic bovine leukosis

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    Peptides present in phages were selected using phage display technology and immunoassays to find out the antigenic mimetics of immunodominant epitopes of bovine leukosis virus (BLV). The use of antigenic mimetics may result in the enhancement of the sensitivity and specificity of the serologic diagnosis of enzootic bovine leukosis (EBL), contributing directly to disease control. The selections enabled the choice of clones which can be used as potential antigens in the diagnoses of diseases. The synthetic peptide produced from the selected sequences may be considered as an alternative for antigens in the serologic diagnosis of enzootic bovine leukosis.Key words: Diagnostic, antigens, enzootic bovine leukosis (EBL), phage display

    P-selectin glycoprotein ligand 1 promotes T cell lymphoma development and dissemination

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    P-selectin glycoprotein ligand-1 (PSGL-1) is a membrane-bound glycoprotein expressed in lymphoid and myeloid cells. It is a ligand of P-, E- and L-selectin and is involved in T cell trafficking and homing to lymphoid tissues, among other functions. PSGL-1 expression has been implicated in different lymphoid malignancies, so here we aimed to evaluate the involvement of PSGL-1 in T cell lymphomagenesis and dissemination. PSGL-1 was highly expressed at the surface of human and mouse T cell leukemia and lymphoma cell lines. To assess its impact on T cell malignancies, we stably expressed human PSGL-1 (hPSGL-1) in a mouse thymic lymphoma cell line, which expresses low levels of endogenous PSGL-1 at the cell surface. hPSGL-1-expressing lymphoma cells developed subcutaneous tumors in athymic nude mice recipients faster than control empty vector or parental cells. Moreover, the kidneys, lungs and liver of tumor-bearing mice were infiltrated by hPSGL-1-expressing malignant T cells. To evaluate the role of PSGL-1 in lymphoma cell dissemination, we injected intravenously control and hPSGL-1-expressing lymphoma cells in athymic mice. Strikingly, PSGL-1 expression facilitated disease infiltration of the kidneys, as determined by histological analysis and anti-CD3 immunohistochemistry. Together, these results indicate that PSGL-1 expression promotes T cell lymphoma development and dissemination to different organs.We thank Roger McEver, José M Almendral, Hind Medyouf, João T Barata and Neil D Perkins for providing reagents and cells, André Mozes (CBMR Flow Cytometry Unit) for technical assistance and Sara Miranda and Nuno Bastos for immunohistochemistry technical assistance. This work was supported by Fundação para a Ciência e a Tecnologia (Portugal), European Social Fund , European Regional Development Fund ( PTDC/SAU-OBD/103336/2008 , PTDC/MED-ONC/32592/2017 , UID/BIM/04773/2013 , NORTE-01-0145-FEDER-000029 and POCI-01-0145-FEDER-007274 grants, IF/00056/2012 contract to NRdS and SFRH/BD/147979/2019 fellowship to JLP), and Gilead Sciences Portugal (Programa Gilead GÉNESE PGG/038/2017 grant). The authors acknowledge the support of the i3S Scientific Platform Histology and Electron Microscopy , member of the national infrastructure PPBI - Portuguese Platform of Bioimaging ( PPBI-POCI-01-0145-FEDER-022122 ). We thank Roger McEver, Jos? M Almendral, Hind Medyouf, Jo?o T Barata and Neil D Perkins for providing reagents and cells, Andr? Mozes (CBMR Flow Cytometry Unit) for technical assistance and Sara Miranda and Nuno Bastos for immunohistochemistry technical assistance. This work was supported by Funda??o para a Ci?ncia e a Tecnologia (Portugal), European Social Fund, European Regional Development Fund (PTDC/SAU-OBD/103336/2008, PTDC/MED-ONC/32592/2017, UID/BIM/04773/2013, NORTE-01-0145-FEDER-000029 and POCI-01-0145-FEDER-007274 grants, IF/00056/2012 contract to NRdS and SFRH/BD/147979/2019 fellowship to JLP), and Gilead Sciences Portugal (Programa Gilead G?NESE PGG/038/2017 grant). The authors acknowledge the support of the i3S Scientific Platform Histology and Electron Microscopy, member of the national infrastructure PPBI - Portuguese Platform of Bioimaging (PPBI-POCI-01-0145-FEDER-022122)

    Hard X-ray lags in active galactic nuclei: Testing the distant reverberation hypothesis with NGC 6814

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    We present an X-ray spectral and temporal analysis of the variable active galaxy NGC 6814, observed with Suzaku during November 2011. Remarkably, the X-ray spectrum shows no evidence for the soft excess commonly observed amongst other active galaxies, despite its relatively low level of obscuration, and is dominated across the whole Suzaku bandpass by the intrinsic powerlaw-like continuum. Despite this, we clearly detect the presence of a low frequency hard lag of ~1600s between the 0.5-2.0 and 2.0-5.0 keV energy bands at greater than 6-sigma significance, similar to those reported in the literature for a variety of other AGN. At these energies, any additional emission from e.g. a very weak, undetected soft excess, or from distant reflection must contribute less than 3% of the observed countrates (at 90% confidence). Given the lack of any significant continuum emission component other than the powerlaw, we can rule out models that invoke distant reprocessing for the observed lag behavior, which must instead be associated with this continuum emission. These results are fully consistent with a propagating fluctuation origin for the low frequency hard lags, and with the interpretation of the high frequency soft lags - a common feature seen in the highest quality AGN data with strong soft excesses - as reverberation from the inner accretion disk

    Influence of Clinical Status and Parasite Load on Erythropoiesis and Leucopoiesis in Dogs Naturally Infected with Leishmania (Leishmania) chagasi

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    Background: The bone marrow is considered to be an important storage of parasites in Leishmania-infected dogs, although little is known about cellular genesis in this organ during canine visceral leishmaniasis (CVL). Methodology/Principal Findings: The aim of the present study was to evaluate changes in erythropoiesis and leucopoiesis in bone marrow aspirates from dogs naturally infected with Leishmania chagasi and presenting different clinical statuses and bone marrow parasite densities. The evolution of CVL from asymptomatic to symptomatic status was accompanied by increasing parasite density in the bone marrow. The impact of bone marrow parasite density on cellularity was similar in dogs at different clinical stages, with animals in the high parasite density group. Erythroid and eosinophilic hypoplasia, proliferation of neutrophilic precursor cells and significant increases in lymphocytes and plasma cell numbers were the major alterations observed. Differential bone marrow cell counts revealed increases in the myeloid:erythroid ratio associated to increased numbers of granulopoietic cells in the different clinical groups compared with non-infected dogs. Conclusions: Analysis of the data obtained indicated that the assessment of bone marrow constitutes an additional and useful tool by which to elaborate a prognosis for CVL

    Accreting Black Holes

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    This chapter provides a general overview of the theory and observations of black holes in the Universe and on their interpretation. We briefly review the black hole classes, accretion disk models, spectral state classification, the AGN classification, and the leading techniques for measuring black hole spins. We also introduce quasi-periodic oscillations, the shadow of black holes, and the observations and the theoretical models of jets.Comment: 41 pages, 18 figures. To appear in "Tutorial Guide to X-ray and Gamma-ray Astronomy: Data Reduction and Analysis" (Ed. C. Bambi, Springer Singapore, 2020). v3: fixed some typos and updated some parts. arXiv admin note: substantial text overlap with arXiv:1711.1025

    Higher Expression of CCL2, CCL4, CCL5, CCL21, and CXCL8 Chemokines in the Skin Associated with Parasite Density in Canine Visceral Leishmaniasis

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    Several previous studies correlated immunopathological aspects of canine visceral leishmaniasis (CVL) with tissue parasite load and/or the clinical status of the disease. Recently, different aspects of the immune response in Leishmania-infected dogs have been studied, particularly the profile of cytokines in distinct compartments. However, the role of chemokines in disease progression or parasite burdens of the visceralising species represents an important approach for understanding immunopathology in CVL. We found an increase in inflammatory infiltrate, which was mainly composed of mononuclear cells, in the skin of animals presenting severe forms of CVL and high parasite density. Our data also demonstrated that enhanced parasite density is positively correlated with the expression of CCL2, CCL4, CCL5, CCL21, and CXCL8. In contrast, there was a negative correlation between parasite density and CCL24 expression. These findings represent an advance in the knowledge of the involvement of skin inflammatory infiltrates in CVL and the systemic consequences and may contribute to developing a rational strategy for the design of new and more efficient prophylactic tools and immunological therapies against CVL
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