1,099 research outputs found

    Mutations in LAMA5 disrupts a skeletal noncanonical focal adhesion pathway and produces a distinct bent bone dysplasia

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    Resultados de investigaciónIn addition to its structural role in skeletogenesis, the extracellular matrix (ECM), particularly basement membrane proteins, facilitates communication with intracellular signaling pathways and cell to cell interactions to control differentiation, proliferation, migration and survival. Alterations in extracellular proteins cause a number of skeletal disorders and one attributed mechanism results from the deleterious effects of mutated proteins on ECM structure. Yet, the consequences of abnormal ECM on cellular communication remains less well understood. Herein, we describe an unclassified form of bent bone dysplasia caused by recessively inherited mutations in LAMA5, the gene encoding the alpha-5 laminin basement membrane protein. This finding uncovered a mechanism of disease driven by ECM-cell interactions between alpha-5-containing laminins, and integrin- mediated focal adhesion signaling, particularly in cartilage. Loss of LAMA5 altered b1 integrin signaling through the non-canonical kinase PYK2 and the skeletal enriched SRC kinase FYN. Loss of LAMA5 negatively impacted the actin cytoskeleton, vinculin localization, and WNT signaling, tying focal adhesion molecules to key skeletal signaling molecules. This newly described mechanism reveals that a LAMA5-b1 Integrin-PYK2-FYN focal adhesion complex regulatesskeletogenesis and, when dysregulated, produces a distinct skeletal disorder.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

    Classroom assessment and education: challenging the assumptions of socialisation and instrumentality

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    The opportunity offered by the Umea Symposium to probe the intersection of quality and assessment immediately brings into focus a wider issue – that of the quality of education which assessment aspires to support. Prompted by recent research into formative assessment in Scottish primary school contexts, the paper explores how formative assessment has become associated with an overly benign understanding of learning which misrecognises the possibility of undesirable learning and does not seem to address the inherently political nature of education. Having illuminated the potential inequities of formative assessment practices, the paper then asks what role formative assessment might play to support an understanding of education that is not simply about the transmission of traditional social norms, but also aspires to illuminate their social construction and their political nature

    Effect of Drying Conditions and Embedding Materials on Post-Harvest Quantitative Parameters in China Aster (Callistephus chinensis) Flowers

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    The study was undertaken to optimize conditions for dry flower production in China aster flowers. The experiment was conducted with eight treatment combinations consisting of two drying conditions viz., room drying (C1) and sun drying (C2) and four media viz. Sand (M1), Sand:Borax (1:1) (M2), Borax (M3) and Silicagel (M4) with factorial concept in completely randomized design. Per cent weight loss and moisture loss were signiflcantly higher under sun drying and silicagel during the entire process of drying from first day to fourth day. Moisture content was higher under room drying and borax from first day to fourth day

    Evidence for the Role of Instantons in Hadron Structure from Lattice QCD

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    Cooling is used as a filter on a set of gluon fields sampling the Wilson action to selectively remove essentially all fluctuations of the gluon field except for the instantons. The close agreement between quenched lattice QCD results with cooled and uncooled configurations for vacuum correlation functions of hadronic currents and for density-density correlation functions in hadronic bound states provides strong evidence for the dominant role of instantons in determining light hadron structure and quark propagation in the QCD vacuum.Comment: 26 pages in REVTeX, plus 10 figures, uuencoded. Submitted to Physical Review D. MIT-CTP-226

    Bodies, technologies and action possibilities: when is an affordance?

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    Borrowed from ecological psychology, the concept of affordances is often said to offer the social study of technology a means of re-framing the question of what is, and what is not, ‘social’ about technological artefacts. The concept, many argue, enables us to chart a safe course between the perils of technological determinism and social constructivism. This article questions the sociological adequacy of the concept as conventionally deployed. Drawing on ethnographic work on the ways technological artefacts engage, and are engaged by, disabled bodies, we propose that the ‘affordances’ of technological objects are not reducible to their material constitution but are inextricably bound up with specific, historically situated modes of engagement and ways of life

    Electromagnetic vertex function of the pion at T > 0

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    The matrix element of the electromagnetic current between pion states is calculated in quenched lattice QCD at a temperature of T=0.93TcT = 0.93 T_c. The nonperturbatively improved Sheikholeslami-Wohlert action is used together with the corresponding O(a){\cal O}(a) improved vector current. The electromagnetic vertex function is extracted for pion masses down to 360MeV360 {\rm MeV} and momentum transfers Q2≤2.7GeV2Q^2 \le 2.7 {\rm GeV}^2.Comment: 17 pages, 8 figure

    Differences in the chitinolytic activity of mammalian chitinases on soluble and insoluble substrates

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    Chitin is an abundant polysaccharide used by many organisms for structural rigidity and water repulsion. As such, the insoluble crystalline structure of chitin poses significant challenges for enzymatic degradation. Acidic mammalian chitinase, a processive glycosyl hydrolase, is the primary enzyme involved in the degradation of environmental chitin in mammalian lungs. Mutations to acidic mammalian chitinase have been associated with asthma, and genetic deletion in mice increases morbidity and mortality with age. We initially set out to reverse this phenotype by engineering hyperactive acidic mammalian chitinase variants. Using a screening approach with commercial fluorogenic substrates, we identified mutations with consistent increases in activity. To determine whether the activity increases observed were consistent with more biologically relevant chitin substrates, we developed new assays to quantify chitinase activity with insoluble chitin, and identified a one-pot fluorogenic assay that is sufficiently sensitive to quantify changes to activity due to the addition or removal of a carbohydrate-binding domain. We show that the activity increases from our directed evolution screen were lost when insoluble substrates were used. In contrast, naturally occurring gain-of-function mutations gave similar results with oligomeric and insoluble substrates. We also show that activity differences between acidic mammalian chitinase and chitotriosidase are reduced with insoluble substrate, suggesting that previously reported activity differences with oligomeric substrates may have been driven by differential substrate specificity. These results highlight the need for assays against physiological substrates when engineering metabolic enzymes, and provide a new one-pot assay that may prove to be broadly applicable to engineering glycosyl hydrolases
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