52 research outputs found
The Nature and Measurement of Secondary School Students\u27 Attitudes Toward Reading
In recent years attitudinal goals have increasingly become a planned facet of school curricula. As a result teachers have become more involved in assessing students\u27 attitudes toward what is being taught. Reading is certainly one area that receives considerable attention in this respect. Secondary teachers and administrators have come to realize that improving students\u27 attitudes toward reading is every bit as important as improving their reading comprehension, word recognition and word analysis skills
The evolution of nuclear auxin signalling
<p>Abstract</p> <p>Background</p> <p>The plant hormone auxin directs many aspects of plant growth and development. To understand the evolution of auxin signalling, we compared the genes encoding two families of crucial transcriptional regulators, <it>AUXIN RESPONSE FACTOR </it>(<it>ARF</it>) and <it>AUXIN/INDOLE-3-ACETIC ACID </it>(<it>Aux/IAA</it>), among flowering plants and two non-seed plants, <it>Physcomitrella patens </it>and <it>Selaginella moellendorffii</it>.</p> <p>Results</p> <p>Comparative analysis of the <it>P. patens, S. moellendorffii </it>and <it>Arabidopsis thaliana </it>genomes suggests that the well-established rapid transcriptional response to auxin of flowering plants, evolved in vascular plants after their divergence from the last common ancestor shared with mosses. An N-terminally truncated ARF transcriptional activator is encoded by the genomes of <it>P. patens </it>and <it>S. moellendorffii</it>, and suggests a supplementary mechanism of nuclear auxin signalling, absent in flowering plants. Site-specific analyses of positive Darwinian selection revealed relatively high rates of synonymous substitution in the <it>A. thaliana </it>ARFs of classes IIa (and their closest orthologous genes in poplar) and Ib, suggesting that neofunctionalization in important functional regions has driven the evolution of auxin signalling in flowering plants. Primary auxin responsive gene families (GH3, SAUR, LBD) show different phylogenetic profiles in <it>P. patens</it>, <it>S. moellendorffii </it>and flowering plants, highlighting genes for further study.</p> <p>Conclusion</p> <p>The genome of <it>P. patens </it>encodes all of the basic components necessary for a rapid auxin response. The spatial separation of the Q-rich activator domain and DNA-binding domain suggests an alternative mechanism of transcriptional control in <it>P. patens </it>distinct from the mechanism seen in flowering plants. Significantly, the genome of <it>S. moellendorffii </it>is predicted to encode proteins suitable for both methods of regulation.</p
Ethylene negatively regulates transcript abundance of ROP-GAP rheostat-encoding genes and affects apoplastic reactive oxygen species homeostasis in epicarps of cold stored apple fruits
Apple (Malus
7domestica Borkh) fruits are stored for long periods of time at low temperatures (1 \ub0C) leading to the occurrence of physiological disorders. 'Superficial scald' of Granny Smith apples, an economically important ethylene-dependent disorder, was used as a model to study relationships among ethylene action, the regulation of the ROP-GAP rheostat, and maintenance of H2O2 homeostasis in fruits during prolonged cold exposure. The ROP-GAP rheostat is a key module for adaptation to low oxygen in Arabidopsis through Respiratory Burst NADPH Oxidase Homologs (RBOH)-mediated and ROP GTPase-dependent regulation of reactive oxygen species (ROS) homeostasis. Here, it was shown that the transcriptional expression of several components of the apple ROP-GAP machinery, including genes encoding RBOHs, ROPs, and their ancillary proteins ROP-GEFs and ROP-GAPs, is coordinately and negatively regulated by ethylene in conjunction with the progressive impairment of apoplastic H2O2 homeostatic levels. RNA sequencing analyses showed that several components of the known ROP- and ROS-associated transcriptional networks are regulated along with the ROP-GAP rheostat in response to ethylene perception. These findings may extend the role of the ROP-GAP rheostat beyond hypoxic responses and suggest that it may be a functional regulatory node involved in the integration of ethylene and ROS signalling pathways in abiotic stress
Exact constraints and appropriate norms in machine learned exchange-correlation functionals
Machine learning techniques have received growing attention as an alternative strategy for developing general-purpose density functional approximations, augmenting the historically successful approach of human-designed functionals derived to obey mathematical constraints known for the exact exchange-correlation functional. More recently, efforts have been made to reconcile the two techniques, integrating machine learning and exact-constraint satisfaction. We continue this integrated approach, designing a deep neural network that exploits the exact constraint and appropriate norm philosophy to de-orbitalize the strongly constrained and appropriately normed (SCAN) functional. The deep neural network is trained to replicate the SCAN functional from only electron density and local derivative information, avoiding the use of the orbital-dependent kinetic energy density. The performance and transferability of the machine-learned functional are demonstrated for molecular and periodic systems
A necroptosis-independent function of RIPK3 promotes immune dysfunction and prevents control of chronic LCMV infection
Necroptosis is a lytic and inflammatory form of cell death that is highly constrained to mitigate detrimental collateral tissue damageand impaired immunity. These constraints make it difficult to define the relevance of necroptosis in diseases such as chronic andpersistent viral infections and within individual organ systems. The role of necroptotic signalling is further complicated becauseproteins essential to this pathway, such as receptor interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain-like(MLKL), have been implicated in roles outside of necroptotic signalling. We sought to address this issue by individually defining therole of RIPK3 and MLKL in chronic lymphocytic choriomeningitis virus (LCMV) infection. We investigated if necroptosis contributesto the death of LCMV-specific CD8+ T cells or virally infected target cells during infection. We provide evidence showing thatnecroptosis was redundant in the pathogenesis of acute forms of LCMV (Armstrong strain) and the early stages of chronic (Docilestrain) LCMV infection in vivo. The number of immune cells, their specificity and reactivity towards viral antigens and viral loads arenot altered in the absence of either MLKL or RIPK3 during acute and during the early stages of chronic LCMV infection. However, weidentified that RIPK3 promotes immune dysfunction and prevents control of infection at later stages of chronic LCMV disease. Thiswas not phenocopied by the loss of MLKL indicating that the phenotype was driven by a necroptosis-independent function ofRIPK3. We provide evidence that RIPK3 signaling evoked a dysregulated type 1 interferone response which we linked to animpaired antiviral immune response and abrogated clearance of chronic LCMV infectio
Auxin-Induced Plasma Membrane Depolarization Is Regulated by Auxin Transport and Not by AUXIN BINDING PROTEIN1
Auxin is a molecule, which controls many aspects of plant development through both transcriptional and non-transcriptional signaling responses. AUXIN BINDING PROTEIN1 (ABP1) is a putative receptor for rapid non-transcriptional auxin-induced changes in plasma membrane depolarization and endocytosis rates. However, the mechanism of ABP1-mediated signaling is poorly understood. Here we show that membrane depolarization and endocytosis inhibition are ABP1-independent responses and that auxin-induced plasma membrane depolarization is instead dependent on the auxin influx carrier AUX1. AUX1 was itself not involved in the regulation of endocytosis. Auxin-dependent depolarization of the plasma membrane was also modulated by the auxin efflux carrier PIN2. These data establish a new connection between auxin transport and non-transcriptional auxin signaling
Structural and electronic studies of substituted m-terphenyl lithium complexes
The effect of para-substitution upon the structural and electronic properties of a series of m-terphenyl lithium complexes [R–Ar#–Li]2 (R = t-Bu 1, SiMe32, H 3, Cl 4, CF35; where R–Ar# = 2,6-{2,6-Xyl}2-4-R-C6H2 and 2,6-Xyl = 2,6-Me2C6H3) has been investigated. X-ray crystallography reveals the complexes to be structurally similar, with little variation in C–M–C bond lengths and angles across the series. However, in-depth NMR spectroscopic studies reveal notable electronic differences, showing a linear correlation between the 7Li{1H} NMR chemical shifts of the para-substituted complexes and their Hammett constants. The flanking methyl protons exhibit a similar electronic shift in the 1H NMR spectra, which has been rationalised by the presence of through-space Li⋯H interactions, as evidenced by two-dimensional 7Li–1H heteronuclear Overhauser spectroscopy (HOESY). In both cases, electron-withdrawing substituents are found to cause an upfield peak shift. A computational analysis is employed to account for these trends.We acknowledge the EPSRC [grant number EP/R004064/1], the Leverhulme Trust [grant number RPG-2014-317], and the University of Nottingham for financial support of this research. We also thank the University of Nottingham Analytical Services Team for elemental analyses, mass spectrometry, and NMR spectroscopy measurements. We are also grateful for access to the University of Nottingham's Augusta High Performance Computing service. AMT is grateful for support from the European Research Council under H2020/ERC Consolidator Grant “topDFT” (Grant No. 772259).Peer reviewe
Structural and Electronic Studies of Substituted m-Terphenyl Group 12 Complexes
The effects of para-substitution on the structural and electronic properties of four series of two-coordinate m-terphenyl Group 12 complexes (R-Ar#)2M (M = Zn, Cd, Hg; R = t-Bu 1–3, SiMe34–6, Cl 7–9, CF310–12, where R-Ar# = 2,6-{2,6-Xyl}2-4-R-C6H2 and 2,6-Xyl = 2,6-Me2C6H3) have been investigated. X-ray crystallography shows little structural variation across the series, with no significant change in the C–M–C bond distances and angles. However, considerable electronic differences are revealed by heteronuclear nuclear magnetic resonance (NMR) spectroscopy; a linear correlation is observed between the 113Cd, 199Hg, and 1H (2,6-Xyl methyl protons) NMR chemical shifts of the para-substituted complexes and the Hammett constants for the R-substituents. Specifically, an upfield shift in the NMR signal is observed with increasingly electron-withdrawing R-substituents. Density functional theory (DFT) calculations are employed to attempt to rationalize these trends
Severe paraneoplastic hypoglycemia in a patient with a gastrointestinal stromal tumor with an exon 9 mutation: a case report
BACKGROUND: Non-islet cell tumor induced hypoglycemia (NICTH) is a very rare phenomenon, but even more so in gastrointestinal stromal tumors. It tends to present in large or metastatic tumors, and can appear at any time in the progression of the disease. We present herein a case of NICTH in a GIST tumor and report an exon 9 mutation associated to it. CASE PRESENTATION: A thirty nine year-old man with a recurrent, metastatic gastrointestinal stromal tumor presented to the hospital with nausea, dizziness, loss of consciousness, and profound hypoglycemia (20 mg/dL). There was no evidence of factitious hypoglycemia. He was stabilized with a continuous glucose infusion and following selective vascular embolization, the patient underwent debulking of a multicentric 40 cm × 25 cm × 10 cm gastrointestinal stromal tumor. After resection, the patient became euglycemic and returned to his normal activities. Tumor analysis confirmed excessive production of insulin-like growth factor II m-RNA and the precursor protein, "big" insulin-like growth factor II. Mutational analysis also identified a rare, 6 bp tandem repeat insert (gcctat) at position 1530 in exon 9 of KIT. CONCLUSION: Optimal management of gastrointestinal stromal tumor-induced hypoglycemia requires a multidisciplinary approach, and surgical debulking is the treatment of choice to obtain immediate symptom relief. Imatinib or combinations of glucocorticoids and growth hormone are alternative palliative strategies for symptomatic hypoglycemia. In addition, mutations in exon 9 of the tyrosine kinase receptor KIT occur in 11–20% of GIST and are often associated with poor patient outcomes. The association of this KIT mutation with non-islet cell tumor induced hypoglycemia has yet to be established
Endothelial Caspase-8 prevents fatal necroptotic hemorrhage caused by commensal bacteria
Caspase-8 transduces signals from death receptor ligands, such as tumor necrosis factor, to drive potent responses including inflammation, cell proliferation or cell death. This is a developmentally essential function because in utero deletion of endothelial Caspase-8 causes systemic circulatory collapse during embryogenesis. Whether endothelial Caspase-8 is also required for cardiovascular patency during adulthood was unknown. To address this question, we used an inducible Cre recombinase system to delete endothelial Casp8 in 6-week-old conditionally gene-targeted mice. Extensive whole body vascular gene targeting was confirmed, yet the dominant phenotype was fatal hemorrhagic lesions exclusively within the small intestine. The emergence of these intestinal lesions was not a maladaptive immune response to endothelial Caspase-8-deficiency, but instead relied upon aberrant Toll-like receptor sensing of microbial commensals and tumor necrosis factor receptor signaling. This lethal phenotype was prevented in compound mutant mice that lacked the necroptotic cell death effector, MLKL. Thus, distinct from its systemic role during embryogenesis, our data show that dysregulated microbial- and death receptor-signaling uniquely culminate in the adult mouse small intestine to unleash MLKL-dependent necroptotic hemorrhage after loss of endothelial Caspase-8. These data support a critical role for Caspase-8 in preserving gut vascular integrity in the face of microbial commensals.<br/
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