142 research outputs found

    The Hubble Deep Field South Flanking Fields

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    As part of the Hubble Deep Field South program, a set of shorter 2-orbit observations were obtained of the area adjacent to the deep fields. The WFPC2 flanking fields cover a contiguous solid angle of 48 square arcminutes. Parallel observations with the STIS and NICMOS instruments produce a patchwork of additional fields with optical and near-infrared (1.6 micron) response. Deeper parallel exposures with WFPC2 and NICMOS were obtained when STIS observed the NICMOS deep field. These deeper fields are offset from the rest, and an extended low surface brightness object is visible in the deeper WFPC2 flanking field. In this data paper, which serves as an archival record of the project, we discuss the observations and data reduction, and present SExtractor source catalogs and number counts derived from the data. Number counts are broadly consistent with previous surveys from both ground and space. Among other things, these flanking field observations are useful for defining slit masks for spectroscopic follow-up over a wider area around the deep fields, for studying large-scale structure that extends beyond the deep fields, for future supernova searches, and for number counts and morphological studies, but their ultimate utility will be defined by the astronomical community.Comment: 46 pages, 15 figures. Images and full catalogs available via the HDF-S at http://www.stsci.edu/ftp/science/hdfsouth/hdfs.html at present. The paper is accepted for the February 2003 Astronomical Journal. Full versions of the catalogs will also be available on-line from AJ after publicatio

    Progenitor-Derivative Relationships of Hordeum Polyploids (Poaceae, Triticeae) Inferred from Sequences of TOPO6, a Nuclear Low-Copy Gene Region

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    Polyploidization is a major mechanism of speciation in plants. Within the barley genus Hordeum, approximately half of the taxa are polyploids. While for diploid species a good hypothesis of phylogenetic relationships exists, there is little information available for the polyploids (4×, 6×) of Hordeum. Relationships among all 33 diploid and polyploid Hordeum species were analyzed with the low-copy nuclear marker region TOPO6 for 341 Hordeum individuals and eight outgroup species. PCR products were either directly sequenced or cloned and on average 12 clones per individual were included in phylogenetic analyses. In most diploid Hordeum species TOPO6 is probably a single-copy locus. Most sequences found in polyploid individuals phylogenetically cluster together with sequences derived from diploid species and thus allow the identification of parental taxa of polyploids. Four groups of sequences occurring only in polyploid taxa are interpreted as footprints of extinct diploid taxa, which contributed to allopolyploid evolution. Our analysis identifies three key species involved in the evolution of the American polyploids of the genus. (i) All but one of the American tetraploids have a TOPO6 copy originating from the Central Asian diploid H. roshevitzii, the second copy clustering with different American diploid species. (ii) All hexaploid species from the New World have a copy of an extinct close relative of H. californicum and (iii) possess the TOPO6 sequence pattern of tetraploid H. jubatum, each with an additional copy derived from different American diploids. Tetraploid H. bulbosum is an autopolyploid, while the assumed autopolyploid H. brevisubulatum (4×, 6×) was identified as allopolyploid throughout most of its distribution area. The use of a proof-reading DNA polymerase in PCR reduced the proportion of chimerical sequences in polyploids in comparison to Taq polymerase

    A20 (Tnfaip3) Deficiency in Myeloid Cells Protects against Influenza A Virus Infection

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    The innate immune response provides the first line of defense against viruses and other pathogens by responding to specific microbial molecules. Influenza A virus (IAV) produces double-stranded RNA as an intermediate during the replication life cycle, which activates the intracellular pathogen recognition receptor RIG-I and induces the production of proinflammatory cytokines and antiviral interferon. Understanding the mechanisms that regulate innate immune responses to IAV and other viruses is of key importance to develop novel therapeutic strategies. Here we used myeloid cell specific A20 knockout mice to examine the role of the ubiquitin-editing protein A20 in the response of myeloid cells to IAV infection. A20 deficient macrophages were hyperresponsive to double stranded RNA and IAV infection, as illustrated by enhanced NF-κB and IRF3 activation, concomitant with increased production of proinflammatory cytokines, chemokines and type I interferon. In vivo this was associated with an increased number of alveolar macrophages and neutrophils in the lungs of IAV infected mice. Surprisingly, myeloid cell specific A20 knockout mice are protected against lethal IAV infection. These results challenge the general belief that an excessive host proinflammatory response is associated with IAV-induced lethality, and suggest that under certain conditions inhibition of A20 might be of interest in the management of IAV infections

    Monthly variation in the probability of presence of adult Culicoides populations in nine European countries and the implications for targeted surveillance

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    Background: Biting midges of the genus Culicoides (Diptera: Ceratopogonidae) are small hematophagous insects responsible for the transmission of bluetongue virus, Schmallenberg virus and African horse sickness virus to wild and domestic ruminants and equids. Outbreaks of these viruses have caused economic damage within the European Union. The spatio-temporal distribution of biting midges is a key factor in identifying areas with the potential for disease spread. The aim of this study was to identify and map areas of neglectable adult activity for each month in an average year. Average monthly risk maps can be used as a tool when allocating resources for surveillance and control programs within Europe. Methods : We modelled the occurrence of C. imicola and the Obsoletus and Pulicaris ensembles using existing entomological surveillance data from Spain, France, Germany, Switzerland, Austria, Denmark, Sweden, Norway and Poland. The monthly probability of each vector species and ensembles being present in Europe based on climatic and environmental input variables was estimated with the machine learning technique Random Forest. Subsequently, the monthly probability was classified into three classes: Absence, Presence and Uncertain status. These three classes are useful for mapping areas of no risk, areas of high-risk targeted for animal movement restrictions, and areas with an uncertain status that need active entomological surveillance to determine whether or not vectors are present. Results: The distribution of Culicoides species ensembles were in agreement with their previously reported distribution in Europe. The Random Forest models were very accurate in predicting the probability of presence for C. imicola (mean AUC = 0.95), less accurate for the Obsoletus ensemble (mean AUC = 0.84), while the lowest accuracy was found for the Pulicaris ensemble (mean AUC = 0.71). The most important environmental variables in the models were related to temperature and precipitation for all three groups. Conclusions: The duration periods with low or null adult activity can be derived from the associated monthly distribution maps, and it was also possible to identify and map areas with uncertain predictions. In the absence of ongoing vector surveillance, these maps can be used by veterinary authorities to classify areas as likely vector-free or as likely risk areas from southern Spain to northern Sweden with acceptable precision. The maps can also focus costly entomological surveillance to seasons and areas where the predictions and vector-free status remain uncertain

    Single-cell analysis implicates Th17-to-Th2 cell plasticity in the pathogenesis of palmoplantar pustulosis

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    Background Palmoplantar pustulosis (PPP) is a severe inflammatory skin disorder, characterised by eruptions of painful, neutrophil-filled pustules on the palms and soles. While PPP has a profound effect on quality of life, it remains poorly understood and notoriously difficult to treat. Objective We sought to investigate the immune pathways that underlie the pathogenesis of PPP. Methods We applied bulk- and single-cell RNA-sequencing methods to the analysis of skin biopsies and peripheral blood mononuclear cells. We validated our results by flow cytometry and immune fluorescence microscopy Results Bulk RNA-sequencing of patient skin detected an unexpected signature of T-cell activation, with a significant overexpression of several Th2 genes typically upregulated in atopic dermatitis. To further explore these findings, we carried out single-cell RNA-sequencing in peripheral blood mononuclear cells of healthy and affected individuals. We found that the memory CD4+T-cells of PPP patients were skewed towards a Th17 phenotype, a phenomenon that was particularly significant among CLA+ skin-homing cells. We also identified a subset of memory CD4+ T-cells which expressed both Th17 (KLRB1/CD161) and Th2 (GATA3) markers, with pseudo-time analysis suggesting that the population was the result of Th17 to Th2 plasticity. Interestingly, the GATA3+/CD161+ cells were over-represented among the PBMCs of affected individuals, both in the scRNA-seq dataset and in independent flow-cytometry experiments. Dual positive cells were also detected in patient skin by means of immune fluorescence microscopy. Conclusions These observations demonstrate that PPP is associated with complex T-cell activation patterns and may explain why biologics that target individual T-helper populations have shown limited therapeutic efficacy. Clinical implications The simultaneous activation of Th17 and Th2 responses in PPP supports the therapeutic use of agents that inhibit multiple T-cell pathways

    The universal values of science and China’s Nobel Prize pursuit

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    China does not seem to believe the existence of universally acknowledged values in science and fails to promote the observation of such values that also should be applied to every member of the scientific community and at all times. Or, there is a separation between the practice of science in China and the values represented by modern science. In this context, science, including the pursuit of the Nobel Prize, is more a pragmatic means to achieve the end of the political leadership – the national pride in this case – than an institution laden with values that govern its practices. However, it is the recognition and respect of the latter that could lead to achievement of the former, rather than the other way around

    A communal catalogue reveals Earth's multiscale microbial diversity

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    Our growing awareness of the microbial world's importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth's microbial diversity.Peer reviewe
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