2,696 research outputs found

    Homeoprotein Hbx4 represses adhesion molecule governing cytokinesis and development

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    Homeobox genes encode proteins with a highly conserved DNA-binding motif and provoke morphological diversification of body segments by differentially controlling the expression of downstream targets. Here, we have identified _hbx4_, one of many homeobox genes in _Dictyostelium discoideum_ and investigated its role during growth and development. In suspension, Hbx4-overexpressing cells, Hbx4^OE^, showed defects in cytokinesis and growth rate. During development, Hbx4^OE^ and _hbx4_-disrupting cells, _hbx4¯_ made differences in shape of mound and slug, cell-type proportioning from wild type KAx3 cells. These phenotypes were similar to those of mutant defective in _cadA_ encoding Ca^2+^-dependent cell adhesion molecule so that we investigated the relationship between _hbx4_ and _cadA_. Overexpression of Hbx4 inhibited the expression of _cadA_ and cAMP also failed to stimulate _cadA_ in Hbx4^OE^. Furthermore, gel mobility shift assay showed the promoter of _cadA_ contained Hbx4-binding site, indicating Hbx4 negatively regulates the expression of _cadA_. Proteome analysis revealed that overexpression of Hbx4 repressed the _rdiA_ and _abpB_ encoding rho guanine nucleotide dissociation inhibitor1, RhoGDI1 and actin bundling protein 34, ABP34, respectively. And the overexpression of _cadA_ in Hbx4^OE^ cells rescued the defects and increased mRNA level of _rdiA_, _abpB_ and one of Rho GTPase, _rac1b_. These results suggested that Hbx4 can modulate cytokinesis, cell sorting and cell-type proportioning by repressing _cadA_ that regulates GTPase-dependent signaling pathway

    Lactobacillus Kimchicus-fermented Ficus caria fruits and leaves extract as an inhibitor of α-MSH-mediated melanogenesis in B16F10 mouse melanoma cells

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    Purpose: To explore the anti-melanogenetic effects of Lactobacillus Kimchicus-fermented Ficus caria fruits and leaves extracts (KFFE) in B16F10 mouse melanoma cells.Methods: The anti-melanogenetic effects of Lactobacillus Kimchicus-fermented Ficus caria fruit and leaf extracts (KFFE) were assessed using melanin contents assay and tyrosinase expression and activity assay in α-MSH-treated B16F10 mouse melanoma cells.Results: The KFFE reduced α-MSH-mediated melanin synthesis in B16F10 mouse melanoma cells, while the tyrosinase mRNA expression was down-regulated by KFFE in B16F10 mouse melanoma cells (p < 0.05). Furthermore, cellular tyrosinase activity was downregulated by KFFE in B16F10 mouse melanoma cells (p < 0.05).Conclusion: KFFE functions to repress melanin synthesis and thus, can potentially be used as a cosmetic ingredient

    Competing Magnetic Orderings and Tunable Topological States in Two-Dimensional Hexagonal Organometallic Lattices

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    The exploration of topological states is of significant fundamental and practical importance in contemporary condensed matter physics, for which the extension to two-dimensional (2D) organometallic systems is particularly attractive. Using first-principles calculations, we show that a 2D hexagonal triphenyl-lead lattice composed of only main group elements is susceptible to a magnetic instability, characterized by a considerably more stable antiferromagnetic (AFM) insulating state rather than the topologically nontrivial quantum spin Hall state proposed recently. Even though this AFM phase is topologically trivial, it possesses an intricate emergent degree of freedom, defined by the product of spin and valley indices, leading to Berry curvature-induced spin and valley currents under electron or hole doping. Furthermore, such a trivial band insulator can be tuned into a topologically nontrivial matter by the application of an out-of-plane electric field, which destroys the AFM order, favoring instead ferrimagnetic spin ordering and a quantum anomalous Hall state with a non-zero topological invariant. These findings further enrich our understanding of 2D hexagonal organometallic lattices for potential applications in spintronics and valleytronics.Comment: 9 pages, 8 figure

    Hypergraph-Based Recognition Memory Model for Lifelong Experience

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    Cognitive agents are expected to interact with and adapt to a nonstationary dynamic environment. As an initial process of decision making in a real-world agent interaction, familiarity judgment leads the following processes for intelligence. Familiarity judgment includes knowing previously encoded data as well as completing original patterns from partial information, which are fundamental functions of recognition memory. Although previous computational memory models have attempted to reflect human behavioral properties on the recognition memory, they have been focused on static conditions without considering temporal changes in terms of lifelong learning. To provide temporal adaptability to an agent, in this paper, we suggest a computational model for recognition memory that enables lifelong learning. The proposed model is based on a hypergraph structure, and thus it allows a high-order relationship between contextual nodes and enables incremental learning. Through a simulated experiment, we investigate the optimal conditions of the memory model and validate the consistency of memory performance for lifelong learning

    Pressure-Sensitive Adhesives for Flexible Display Applications

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    Pressure-sensitive adhesives (PSA) have been used in electronics for not only attachment of two materials but also shock absorption, thermal and electrical conductivity, electromagnetic shielding, and optical property. Optically clear adhesives (OCA) have been used as a core material for optical performance of display. In addition to basic properties of OCA such as adhesion strength, transmittance, haze, and reliability, it has required dielectric constant, gap filling, and anticorrosion according to a substrate. However, the structural and functional changes of flexible display bring challenges to OCA that protects vulnerable components such as thin-film transistor, OLED, and thin-film encapsulation by stress dispersion and adjustment of a neutral plane. At the same time, flexibility and existing properties are essential. In this chapter, the development of components and performance of OCA, and evaluation methods will be discussed

    Higgs Phenomenology of Scalar Sequestering

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    The light Higgs mass in the MSSM is highly constrained and is predicted to be close to M_Z which causes a tension between the LEP II Higgs mass bound 114 GeV and the natural electroweak symmetry breaking in the MSSM. The usual way to increase the light CP even Higgs mass was to increase the quartic coupling of the up type Higgs. We point out that the light Higgs mass can be increased by reducing the off-diagonal term in the mass matrix when tan beta is moderate, which is about 5 to 10. As a result no mixing and/or a Higgs mixing angle of the opposite sign arises and the branching ratio of Higgs decay is drastically changed. This is possible in scalar sequestering scenario in which mu parameter can be large independently of the electroweak symmetry breaking. We also discuss the same effect in the BMSSM.Comment: 20 pages, 6 figure

    The voltage-gated potassium channel Shaker promotes sleep via thermosensitive GABA transmission

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    Genes and neural circuits coordinately regulate animal sleep. However, it remains elusive how these endogenous factors shape sleep upon environmental changes. Here, we demonstrate that Shaker (Sh)-expressing GABAergic neurons projecting onto dorsal fan-shaped body (dFSB) regulate temperature-adaptive sleep behaviors in Drosophila. Loss of Sh function suppressed sleep at low temperature whereas light and high temperature cooperatively gated Sh effects on sleep. Sh depletion in GABAergic neurons partially phenocopied Sh mutants. Furthermore, the ionotropic GABA receptor, Resistant to dieldrin (Rdl), in dFSB neurons acted downstream of Sh and antagonized its sleep-promoting effects. In fact, Rdl inhibited the intracellular cAMP signaling of constitutively active dopaminergic synapses onto dFSB at low temperature. High temperature silenced GABAergic synapses onto dFSB, thereby potentiating the wake-promoting dopamine transmission. We propose that temperature-dependent switching between these two synaptic transmission modalities may adaptively tune the neural property of dFSB neurons to temperature shifts and reorganize sleep architecture for animal fitness. Ji-hyung Kim and Yoonhee Ki et al. show that low temperatures suppress sleep in Drosophila by increasing GABA transmission in Shaker-expressing GABAergic neurons projecting onto the dorsal fan-shaped body, while high temperatures potentiate dopamine-induced arousal by reducing GABA transmission. This study highlights a role for Shaker in sleep modulation via a temperature-dependent switch in GABA signaling

    Nasal Chondromesenchymal Hamartoma: CT and MR Imaging Findings

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    We report CT and MR imaging findings for a case of nasal chondromesenchymal hamartoma occurring in a 19-month-old boy. A nasal chondromesenchymal hamartoma is a rare benign pediatric hamartoma that can simulate malignancy. Although rare, knowledge of this entity is essential to avoid potentially harmful therapies
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