926 research outputs found

    Expression quantitative trait loci are highly sensitive to cellular differentiation state

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    Blood cell development from multipotent hematopoietic stem cells to specialized blood cells is accompanied by drastic changes in gene expression for which the triggers remain mostly unknown. Genetical genomics is an approach linking natural genetic variation to gene expression variation, thereby allowing the identification of genomic loci containing gene expression modulators (eQTLs). In this paper, we used a genetical genomics approach to analyze gene expression across four developmentally close blood cell types collected from a large number of genetically different but related mouse strains. We found that, while a significant number of eQTLs (365) had a consistent “static” regulatory effect on gene expression, an even larger number were found to be very sensitive to cell stage. As many as 1,283 eQTLs exhibited a “dynamic” behavior across cell types. By looking more closely at these dynamic eQTLs, we show that the sensitivity of eQTLs to cell stage is largely associated with gene expression changes in target genes. These results stress the importance of studying gene expression variation in well-defined cell populations. Only such studies will be able to reveal the important differences in gene regulation between different ce

    Elevated CO<sub>2</sub> does not increase eucalypt forest productivity on a low-phosphorus soil

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    Rising atmospheric CO2 stimulates photosynthesis and productivity of forests, offsetting CO2 emissions. Elevated CO2 experiments in temperate planted forests yielded ~23% increases in productivity over the initial years. Whether similar CO2 stimulation occurs in mature evergreen broadleaved forests on low-phosphorus (P) soils is unknown, largely due to lack of experimental evidence. This knowledge gap creates major uncertainties in future climate projections as a large part of the tropics is P-limited. Here,we increased atmospheric CO2 concentration in a mature broadleaved evergreen eucalypt forest for three years, in the first large-scale experiment on a P-limited site. We show that tree growth and other aboveground productivity components did not significantly increase in response to elevated CO2 in three years, despite a sustained 19% increase in leaf photosynthesis. Moreover, tree growth in ambient CO2 was strongly P-limited and increased by ~35% with added phosphorus. The findings suggest that P availability may potentially constrain CO2-enhanced productivity in P-limited forests; hence, future atmospheric CO2 trajectories may be higher than predicted by some models. As a result, coupled climate-carbon models should incorporate both nitrogen and phosphorus limitations to vegetation productivity in estimating future carbon sinks

    Ex vivo micro-computed tomography analysis of bleomycin-induced lung fibrosis for preclinical drug evaluation.

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    Research into the pathogenesis underlying the development of idiopathic pulmonary fibrosis is hampered by a repertoire of animal models that fail to recapitulate all the features of the human disease. Better use and understanding of what the animal models represent may improve clinical predictability. We interrogated ex vivo micro-computed tomography (CT) as a novel end-point measure in the mouse model of bleomycin-induced lung fibrosis (BILF), and to evaluate a therapeutic dosing regimen for preclinical drug evaluation. A detailed characterisation of BILF was performed using standard end-point measures (lung hydroxyproline and histology). High resolution micro-CT (∼13.7 μm voxel size) was evaluated for quantifying the extent and severity of lung fibrosis. The period from 14 to 28 days following bleomycin instillation represents progression of established fibrosis. A therapeutic dosing regimen during this period was validated using a transforming growth factor-β receptor-1 kinase inhibitor, and micro-CT provided a highly sensitive and quantitative measure of fibrosis. Moreover, fibrotic lesions did not completely resolve, but instead persisted for ≥6 months following a single insult with bleomycin. Ex vivo micro-CT analysis of BILF allows robust evaluation of therapeutic dosing once fibrosis is already well established, requiring fewer mice than conventional biochemical end-points

    Chemical and electronic structure analysis of a SrTiO3(001)/p-Ge (001) hydrogen evolution photocathode

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    Germanium is a small-gap semiconductor that efficiently absorbs visible light, resulting in photoexcited electrons predicted to be sufficiently energetic to reduce H 2 O for H 2 gas evolution. In order to protect the surface from corrosion and prevent surface charge recombination in contact with aqueous pH 7 electrolyte, we grew epitaxial SrTiO 3 layers of different thicknesses on p-Ge (001) surfaces. Four-nanometer SrTiO 3 allows photogenerated electrons to reach the surface and evolve H 2 gas, while 13 nm SrTiO 3 blocks these electrons. Ambient pressure x-ray photoelectron spectroscopy indicates that the surface readily dissociates H 2 O to form OH species, which may impact surface band bending

    Assimilation of healthy and indulgent impressions from labelling influences fullness but not intake or sensory experience

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    Background: Recent evidence suggests that products believed to be healthy may be over-consumed relative to believed indulgent or highly caloric products. The extent to which these effects relate to expectations from labelling, oral experience or assimilation of expectations is unclear. Over two experiments, we tested the hypotheses that healthy and indulgent information could be assimilated by oral experience of beverages and influence sensory evaluation, expected satiety, satiation and subsequent appetite. Additionally, we explored how expectation-experience congruency influenced these factors. Results: Results supported some assimilation of healthiness and indulgent ratings—study 1 showed that indulgent ratings enhanced by the indulgent label persisted post-tasting, and this resulted in increased fullness ratings. In study 2, congruency of healthy labels and oral experience promoted enhanced healthiness ratings. These healthiness and indulgent beliefs did not influence sensory analysis or intake—these were dictated by the products themselves. Healthy labels, but not experience, were associated with decreased expected satiety. Conclusions: Overall labels generated expectations, and some assimilation where there were congruencies between expectation and experience, but oral experience tended to override initial expectations to determine ultimate sensory evaluations and intake. Familiarity with the sensory properties of the test beverages may have resulted in the use of prior knowledge, rather than the label information, to guide evaluations and behaviour

    A rare case of intussusception leading to the diagnosis of acquired immune deficiency syndrome: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Although a common cause of intestinal obstruction in children, intussusception is a rare event in the adult population living in temperate regions. It has long been known that various acquired immune deficiency syndrome related conditions of the bowel such as lymphoma, lymphoid hyperplasia, cytomegalovirus colitis and Kaposi's sarcoma can lead to intussusception. The diagnosis is particularly difficult in this population of patients due to the non-specific nature of the symptoms as well as the depressed immune response obscuring inflammation or ischemia. Though the reported acquired immune deficiency syndrome associated cases of intussusception refer to patients with known human immunodeficiency virus infection, in our case we present an intestinal intussusception as the first manifestation of human immunodeficiency virus infection.</p> <p>Case presentation</p> <p>A 58-year-old white heterosexual Greek man with a clean medical record and no history of abdominal operation presented to the emergency department with symptoms and signs of bowel obstruction. Plain abdominal radiographs were highly suspicious for intussusception which was eventually confirmed on a computed tomography scan. Due to the patients clean medical record as well as the radiologic diagnosis of intussusception, we promptly undertook further serologic tests for human immunodeficiency virus and eventually established the diagnosis of acquired immune deficiency syndrome. The patient was operated 3 days later and this confirmed the diagnosis of small-bowel invagination due to a 4 cm polypoid growing intraluminal tumor, the pathologic examination of which revealed a diffuse high-grade B cell lymphoblastic lymphoma.</p> <p>Conclusion</p> <p>Human immunodeficiency virus infection may have a silent course and gastrointestinal manifestations of the disease leading to intussusception might be the first clinical sign. Patients with intestinal intussusception, and the presence of risk factors for human immunodeficiency virus infection should be eligible for serologic tests for human immunodeficiency virus infection.</p

    Ferromagnetic Semiconductors: Moving Beyond (Ga,Mn)As

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    The recent development of MBE techniques for growth of III-V ferromagnetic semiconductors has created materials with exceptional promise in spintronics, i.e. electronics that exploit carrier spin polarization. Among the most carefully studied of these materials is (Ga,Mn)As, in which meticulous optimization of growth techniques has led to reproducible materials properties and ferromagnetic transition temperatures well above 150 K. We review progress in the understanding of this particular material and efforts to address ferromagnetic semiconductors as a class. We then discuss proposals for how these materials might find applications in spintronics. Finally, we propose criteria that can be used to judge the potential utility of newly discovered ferromagnetic semiconductors, and we suggest guidelines that may be helpful in shaping the search for the ideal material.Comment: 37 pages, 4 figure

    Functional Divergence in the Genus Oenococcus as Predicted by Genome Sequencing of the Newly-Described Species, Oenococcus kitaharae

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    Oenococcus kitaharae is only the second member of the genus Oenococcus to be identified and is the closest relative of the industrially important wine bacterium Oenococcus oeni. To provide insight into this new species, the genome of the type strain of O. kitaharae, DSM 17330, was sequenced. Comparison of the sequenced genomes of both species show that the genome of O. kitaharae DSM 17330 contains many genes with predicted functions in cellular defence (bacteriocins, antimicrobials, restriction-modification systems and a CRISPR locus) which are lacking in O. oeni. The two genomes also appear to differentially encode several metabolic pathways associated with amino acid biosynthesis and carbohydrate utilization and which have direct phenotypic consequences. This would indicate that the two species have evolved different survival techniques to suit their particular environmental niches. O. oeni has adapted to survive in the harsh, but predictable, environment of wine that provides very few competitive species. However O. kitaharae appears to have adapted to a growth environment in which biological competition provides a significant selective pressure by accumulating biological defence molecules, such as bacteriocins and restriction-modification systems, throughout its genome

    Fluids in cosmology

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    We review the role of fluids in cosmology by first introducing them in General Relativity and then by applying them to a FRW Universe's model. We describe how relativistic and non-relativistic components evolve in the background dynamics. We also introduce scalar fields to show that they are able to yield an inflationary dynamics at very early times (inflation) and late times (quintessence). Then, we proceed to study the thermodynamical properties of the fluids and, lastly, its perturbed kinematics. We make emphasis in the constrictions of parameters by recent cosmological probes.Comment: 34 pages, 4 figures, version accepted as invited review to the book "Computational and Experimental Fluid Mechanics with Applications to Physics, Engineering and the Environment". Version 2: typos corrected and references expande
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