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  • 1
    Publication Date: 2018-04-28
    Description: A topological insulator film coupled to a simple isotropic s-wave superconductor substrate can foster helical pairing of the Dirac fermions associated with the topological surface states. Experimental realization of such a system is exceedingly difficult, however using a novel "flip-chip" technique, we have prepared single-crystalline Bi 2 Se 3 films with predetermined thicknesses in terms of quintuple layers (QLs) on top of Nb substrates fresh from in situ cleavage. Our angle-resolved photoemission spectroscopy (ARPES) measurements of the film surface disclose superconducting gaps and coherence peaks of similar magnitude for both the topological surface states and bulk states. The ARPES spectral map as a function of temperature and film thickness up to 10 QLs reveals key characteristics relevant to the mechanism of coupling between the topological surface states and the superconducting Nb substrate; the effective coupling length is found to be much larger than the decay length of the topological surface states.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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  • 2
    Publication Date: 2018-09-19
    Description: The phenotype gap is a challenge for genetically dissecting redundant endocrine signaling pathways, such as the six isoforms in the insulin-like growth factor binding protein (IGFBP) family. Although overexpressed IGFBPs can inhibit or potentiate IGF actions or have IGF-independent actions, mutant mice lacking IGFBP-encoding genes do not exhibit major phenotypes. We found that although zebrafish deficient in igfbp5a did not show overt phenotypes when raised in Ca 2+ -rich solutions, they died prematurely in low Ca 2+ conditions. A group of epithelial cells expressing igfbp5a take up Ca 2+ and proliferate under low Ca 2+ conditions because of activation of IGF signaling. Deletion of igfbp5a blunted low Ca 2+ stress–induced IGF signaling and impaired adaptive proliferation. Reintroducing zebrafish Igfbp5a, but not its ligand binding–deficient mutant, restored adaptive proliferation. Similarly, adaptive proliferation was restored in zebrafish lacking igfbp5a by expression of human IGFBP5, but not two cancer-associated IGFBP5 mutants. Knockdown of IGFBP5 in human colon carcinoma cells resulted in reduced IGF-stimulated cell proliferation. These results reveal a conserved mechanism by which a locally expressed Igfbp regulates organismal Ca 2+ homeostasis and survival by activating IGF signaling in epithelial cells and promoting their proliferation in Ca 2+ -deficient states. These findings underscore the importance of physiological context when analyzing loss-of-function phenotypes of endocrine factors.
    Print ISSN: 1945-0877
    Topics: Medicine
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  • 3
    Publication Date: 2018-02-16
    Description: Purpose: Intratumoral androgen synthesis (IAS) is a key mechanism promoting androgen receptor (AR) reactivation and antiandrogen resistance in castration-resistant prostate cancer (CRPC). However, signaling pathways driving aberrant IAS remain poorly understood. Experimental Design: The effect of components of the AKT-RUNX2-osteocalcin (OCN)–GPRC6A–CREB signaling axis on expression of steroidogenesis genes CYP11A1 and CYP17A1 and testosterone level were examined in PTEN-null human prostate cancer cell lines. Pten knockout mice were used to examine the effect of Runx2 heterozygous deletion or abiraterone acetate (ABA), a prodrug of the CYP17A1 inhibitor abiraterone on Cyp11a1 and Cyp17a1 expression, testosterone level and tumor microenvironment (TME) remodeling in vivo . Results: We uncovered that activation of the AKT–RUNX2–OCN–GPRC6A–CREB signaling axis induced expression of CYP11A1 and CYP17A1 and testosterone production in PTEN-null prostate cancer cell lines in culture. Deletion of Runx2 in Pten homozygous knockout prostate tumors decreased Cyp11a1 and Cyp17a1 expression, testosterone level, and tumor growth in castrated mice. ABA treatment also inhibited testosterone synthesis and alleviated Pten loss-induced tumorigenesis in vivo . Pten deletion induced TME remodeling, but Runx2 heterozygous deletion or ABA treatment reversed the effect of Pten loss by decreasing expression of the collagenase Mmp9. Conclusions: Abnormal RUNX2 activation plays a pivotal role in PTEN loss-induced IAS and TME remodeling, suggesting that the identified signaling cascade represents a viable target for effective treatment of PTEN-null prostate cancer, including CRPC. Clin Cancer Res; 24(4); 834–46. ©2017 AACR .
    Print ISSN: 1078-0432
    Electronic ISSN: 1557-3265
    Topics: Medicine
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  • 4
    Publication Date: 2012-12-04
    Description: Ionic protein-lipid interactions are critical for the structure and function of membrane receptors, ion channels, integrins and many other proteins. However, the regulatory mechanism of these interactions is largely unknown. Here we show that Ca(2+) can bind directly to anionic phospholipids and thus modulate membrane protein function. The activation of T-cell antigen receptor-CD3 complex (TCR), a key membrane receptor for adaptive immunity, is regulated by ionic interactions between positively charged CD3epsilon/zeta cytoplasmic domains (CD3(CD)) and negatively charged phospholipids in the plasma membrane. Crucial tyrosines are buried in the membrane and are largely protected from phosphorylation in resting T cells. It is not clear how CD3(CD) dissociates from the membrane in antigen-stimulated T cells. The antigen engagement of even a single TCR triggers a Ca(2+) influx and TCR-proximal Ca(2+) concentration is higher than the average cytosolic Ca(2+) concentration. Our biochemical, live-cell fluorescence resonance energy transfer and NMR experiments showed that an increase in Ca(2+) concentration induced the dissociation of CD3(CD) from the membrane and the solvent exposure of tyrosine residues. As a consequence, CD3 tyrosine phosphorylation was significantly enhanced by Ca(2+) influx. Moreover, when compared with wild-type cells, Ca(2+) channel-deficient T cells had substantially lower levels of CD3 phosphorylation after stimulation. The effect of Ca(2+) on facilitating CD3 phosphorylation is primarily due to the charge of this ion, as demonstrated by the fact that replacing Ca(2+) with the non-physiological ion Sr(2+) resulted in the same feedback effect. Finally, (31)P NMR spectroscopy showed that Ca(2+) bound to the phosphate group in anionic phospholipids at physiological concentrations, thus neutralizing the negative charge of phospholipids. Rather than initiating CD3 phosphorylation, this regulatory pathway of Ca(2+) has a positive feedback effect on amplifying and sustaining CD3 phosphorylation and should enhance T-cell sensitivity to foreign antigens. Our study thus provides a new regulatory mechanism of Ca(2+) to T-cell activation involving direct lipid manipulation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shi, Xiaoshan -- Bi, Yunchen -- Yang, Wei -- Guo, Xingdong -- Jiang, Yan -- Wan, Chanjuan -- Li, Lunyi -- Bai, Yibing -- Guo, Jun -- Wang, Yujuan -- Chen, Xiangjun -- Wu, Bo -- Sun, Hongbin -- Liu, Wanli -- Wang, Junfeng -- Xu, Chenqi -- England -- Nature. 2013 Jan 3;493(7430):111-5. doi: 10.1038/nature11699. Epub 2012 Dec 2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23201688" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/*metabolism/pharmacology ; Cell Membrane/metabolism ; Cytoplasm/metabolism ; Feedback, Physiological/drug effects ; Humans ; Jurkat Cells ; Lipid Bilayers/chemistry/metabolism ; *Lymphocyte Activation/drug effects ; Mice ; Phospholipids/*chemistry/*metabolism ; Phosphorylation/drug effects ; Receptor-CD3 Complex, Antigen, T-Cell/drug effects/immunology/*metabolism ; *Signal Transduction/drug effects ; Solvents/chemistry/metabolism ; Static Electricity ; T-Lymphocytes/drug effects/immunology/*metabolism ; Tyrosine/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2015-12-04
    Description: Roots and leaves of healthy plants host taxonomically structured bacterial assemblies, and members of these communities contribute to plant growth and health. We established Arabidopsis leaf- and root-derived microbiota culture collections representing the majority of bacterial species that are reproducibly detectable by culture-independent community sequencing. We found an extensive taxonomic overlap between the leaf and root microbiota. Genome drafts of 400 isolates revealed a large overlap of genome-encoded functional capabilities between leaf- and root-derived bacteria with few significant differences at the level of individual functional categories. Using defined bacterial communities and a gnotobiotic Arabidopsis plant system we show that the isolates form assemblies resembling natural microbiota on their cognate host organs, but are also capable of ectopic leaf or root colonization. While this raises the possibility of reciprocal relocation between root and leaf microbiota members, genome information and recolonization experiments also provide evidence for microbiota specialization to their respective niche.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bai, Yang -- Muller, Daniel B -- Srinivas, Girish -- Garrido-Oter, Ruben -- Potthoff, Eva -- Rott, Matthias -- Dombrowski, Nina -- Munch, Philipp C -- Spaepen, Stijn -- Remus-Emsermann, Mitja -- Huttel, Bruno -- McHardy, Alice C -- Vorholt, Julia A -- Schulze-Lefert, Paul -- England -- Nature. 2015 Dec 17;528(7582):364-9. doi: 10.1038/nature16192. Epub 2015 Dec 2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany. ; Institute of Microbiology, ETH Zurich, 8093 Zurich, Switzerland. ; Department of Algorithmic Bioinformatics, Heinrich Heine University Dusseldorf, 40225 Dusseldorf, Germany. ; Cluster of Excellence on Plant Sciences (CEPLAS), Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany. ; Computational Biology of Infection Research, Helmholtz Center for Infection Research, 38124 Braunschweig, Germany. ; Max-von-Pettenkofer Institute, Ludwig Maximilian University, German Center for Infection Research (DZIF), partner site LMU Munich, 80336 Munich, Germany. ; German Center for Infection Research (DZIF), partner site Hannover-Braunschweig, 38124 Braunschweig, Germany. ; Max Planck Genome Center, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26633631" target="_blank"〉PubMed〈/a〉
    Keywords: Arabidopsis/*microbiology ; Bacteria/classification/genetics/isolation & purification ; Genome, Bacterial/genetics ; Germ-Free Life ; Microbiota/genetics/*physiology ; Plant Leaves/*microbiology ; Plant Roots/*microbiology ; Sequence Analysis, DNA ; Soil Microbiology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2015-06-23
    Description: Stearoyl-CoA desaturase (SCD) is conserved in all eukaryotes and introduces the first double bond into saturated fatty acyl-CoAs. Because the monounsaturated products of SCD are key precursors of membrane phospholipids, cholesterol esters and triglycerides, SCD is pivotal in fatty acid metabolism. Humans have two SCD homologues (SCD1 and SCD5), while mice have four (SCD1-SCD4). SCD1-deficient mice do not become obese or diabetic when fed a high-fat diet because of improved lipid metabolic profiles and insulin sensitivity. Thus, SCD1 is a pharmacological target in the treatment of obesity, diabetes and other metabolic diseases. SCD1 is an integral membrane protein located in the endoplasmic reticulum, and catalyses the formation of a cis-double bond between the ninth and tenth carbons of stearoyl- or palmitoyl-CoA. The reaction requires molecular oxygen, which is activated by a di-iron centre, and cytochrome b5, which regenerates the di-iron centre. To understand better the structural basis of these characteristics of SCD function, here we crystallize and solve the structure of mouse SCD1 bound to stearoyl-CoA at 2.6 A resolution. The structure shows a novel fold comprising four transmembrane helices capped by a cytosolic domain, and a plausible pathway for lateral substrate access and product egress. The acyl chain of the bound stearoyl-CoA is enclosed in a tunnel buried in the cytosolic domain, and the geometry of the tunnel and the conformation of the bound acyl chain provide a structural basis for the regioselectivity and stereospecificity of the desaturation reaction. The dimetal centre is coordinated by a unique spacial arrangement of nine conserved histidine residues that implies a potentially novel mechanism for oxygen activation. The structure also illustrates a possible route for electron transfer from cytochrome b5 to the di-iron centre.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4689147/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4689147/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bai, Yonghong -- McCoy, Jason G -- Levin, Elena J -- Sobrado, Pablo -- Rajashankar, Kanagalaghatta R -- Fox, Brian G -- Zhou, Ming -- P41 GM103403/GM/NIGMS NIH HHS/ -- P41GM103403/GM/NIGMS NIH HHS/ -- R01 DK088057/DK/NIDDK NIH HHS/ -- R01 GM098878/GM/NIGMS NIH HHS/ -- R01 HL086392/HL/NHLBI NIH HHS/ -- R01DK088057/DK/NIDDK NIH HHS/ -- R01GM050853/GM/NIGMS NIH HHS/ -- R01GM098878/GM/NIGMS NIH HHS/ -- R01HL086392/HL/NHLBI NIH HHS/ -- U54 GM094584/GM/NIGMS NIH HHS/ -- U54GM094584/GM/NIGMS NIH HHS/ -- U54GM095315/GM/NIGMS NIH HHS/ -- England -- Nature. 2015 Aug 13;524(7564):252-6. doi: 10.1038/nature14549. Epub 2015 Jun 22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA. ; Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA. ; NE-CAT and Department of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Argonne, Illinois 60439, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26098370" target="_blank"〉PubMed〈/a〉
    Keywords: Acyl Coenzyme A/chemistry/metabolism ; Animals ; Binding Sites ; Crystallography, X-Ray ; Cytochromes b5/chemistry/metabolism ; Electron Transport ; Histidine/chemistry/metabolism ; Iron/metabolism ; Mice ; Models, Molecular ; Oxygen/metabolism ; Protein Structure, Tertiary ; Static Electricity ; Stearoyl-CoA Desaturase/*chemistry/metabolism ; Structure-Activity Relationship
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2015-11-26
    Description: The formation of relativistic jets by an accreting compact object is one of the fundamental mysteries of astrophysics. Although the theory is poorly understood, observations of relativistic jets from systems known as microquasars (compact binary stars) have led to a well established phenomenology. Relativistic jets are not expected to be produced by sources with soft or supersoft X-ray spectra, although two such systems are known to produce relatively low-velocity bipolar outflows. Here we report the optical spectra of an ultraluminous supersoft X-ray source (ULS) in the nearby galaxy M81 (M81 ULS-1; refs 9, 10). Unexpectedly, the spectra show blueshifted, broad Halpha emission lines, characteristic of baryonic jets with relativistic speeds. These time-variable emission lines have projected velocities of about 17 per cent of the speed of light, and seem to be similar to those from the prototype microquasar SS 433 (refs 11, 12). Such relativistic jets are not expected to be launched from white dwarfs, and an origin from a black hole or a neutron star is hard to reconcile with the persistence of M81 ULS-1's soft X-rays. Thus the unexpected presence of relativistic jets in a ULS challenges canonical theories of jet formation, but might be explained by a long-speculated, supercritically accreting black hole with optically thick outflows.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Liu, Ji-Feng -- Bai, Yu -- Wang, Song -- Justham, Stephen -- Lu, You-Jun -- Gu, Wei-Min -- Liu, Qing-Zhong -- Di Stefano, Rosanne -- Guo, Jin-Cheng -- Cabrera-Lavers, Antonio -- Alvarez, Pedro -- Cao, Yi -- Kulkarni, Shri -- England -- Nature. 2015 Dec 3;528(7580):108-10. doi: 10.1038/nature15751. Epub 2015 Nov 25.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012, China. ; College of Astronomy and Space Sciences, University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China. ; Department of Astronomy, Xiamen University, Xiamen, Fujian Province 361005, China. ; Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, Jiangsu Province 210008, China. ; Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA. ; Instituto de Astrofisica de Canarias, c/Via Lactea s/n, E-38200 La Laguna, Tenerife, Spain. ; Departamento de Astrofisica, Universidad de la Laguna, E-38205 La Laguna, Tenerife, Spain. ; Department of Astronomy, Caltech, Pasadena, California 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26605521" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 8
    Publication Date: 2018-06-05
    Description: Objective The goal of this study is to investigate the associations of apolipoprotein A5 ( APOA5 ) polymorphisms with coronary artery disease (CAD) in a Chinese population. Method This case–control study included 710 subjects (355 patients with CAD and 355 controls) who were recruited from a cross-sectional study. Three single nucleotide polymorphisms (SNPs) rs662799 (–1131T〉C), rs651821 (–3A〉G) and rs2075291 (G185C) in APOA5 were selected and genotyped using the matrix-assisted laser desorption ioniasation time of flight mass spectrometry technology. The 2 test and haplotype analysis were performed to analyse the associations between APOA5 SNPs and CAD using the SPSS V.22.0 software package and the online SNPStats program. Results APOA5 SNPs rs662799 and rs651821 exhibited significant differences in genotype and allele distributions between patients with CAD and control subjects. The SNP rs662799 was significantly correlated with an increased risk of CAD when a dominant model was considered. The SNP rs651821 was significantly correlated with an increased risk of CAD when a codominant model was considered. Moreover, the variant C alleles of rs662799 and the variant G alleles of the rs651821 polymorphism were significantly correlated with increased plasma triglyceride (TG) levels in the CAD group (all p〈0.05). Additionally, a mediating effect of TG on the associations between the APOA5 rs662799 and rs651821 polymorphisms and CAD was observed. Conclusion Based on these data, variants of the APOA5 gene are associated with CAD susceptibility and may modulate plasma TG levels among a Chinese population.
    Keywords: Open access, Genetics and genomics
    Electronic ISSN: 2044-6055
    Topics: Medicine
    Published by BMJ Publishing
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  • 9
    Publication Date: 2018-04-28
    Description: Background Hereditary sensorineural hearing loss is a genetically heterogeneous disorder. Objectives This study was designed to explore the genetic etiology of deafness in a large Chinese family with autosomal dominant, nonsyndromic, progressive sensorineural hearing loss (ADNSHL). Methods Whole exome sequencing and linkage analysis were performed to identify pathogenic mutation. Inner ear expression of Ifnlr1 was investigated by immunostaining in mice. ifnlr1 Morpholino knockdown Zebrafish were constructed to explore the deafness mechanism. Results We identified a cosegregating heterozygous missense mutation, c.296G〉A (p.Arg99His) in the gene encoding interferon lambda receptor 1 ( IFNLR1 ) – a protein that functions in the Jak/ STAT pathway– are associated with ADNSHL . Morpholino knockdown of ifnlr1 leads to a significant decrease in hair cells and non-inflation of the swim bladder in late-stage zebrafish, which can be reversed by injection with normal Zebrafish ifnlr1 mRNA. Knockdown of ifnlr1 in zebrafish causes significant upregulation of cytokine receptor family member b4 (interleukin-10r2), jak1, tyrosine kinase 2, stat3, and stat5b in the Jak1/STAT3 pathway at the mRNA level. Conclusion IFNLR1 function is required in the auditory system and that IFNLR1 mutations are associated with ADNSHL. To the best of our knowledge, this is the first study implicating an interferon lambda receptor in auditory function.
    Keywords: Open access
    Print ISSN: 0022-2593
    Electronic ISSN: 1468-6244
    Topics: Medicine
    Published by BMJ Publishing Group
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  • 10
    Publication Date: 2018-05-10
    Description: A hollow fibre membrane was fabricated by blending polyvinylidene fluoride (PVDF) with a triblock copolymer additive polymer that has both hydrophilic and oleophobic surface properties. The novel membrane was characterized and examined for oil/water separation under various system conditions, including different cross-flow rate, feed temperature, trans-membrane pressure, and its rejection and cleaning efficiency, etc. By applying the membrane into the filtration of synthesized oil/water emulsion, the membrane constantly achieved an oil rejection rate of above 99%, with a relatively constant permeate flux varied in the range of 68.9–59.0 l m –2 h –1 . More importantly, the fouling of the used membrane can be easily removed by simple water flushing. The membrane also demonstrated a wide adaptability for different types of real oily wastewater, even at very high feed oil concentration (approx. 115 000 mg l –1 in terms of chemical oxygen demand (COM)). Hence, the novel triblock copolymer additive-modified PVDF membrane can have a great prospect in the continuing effort to expand the engineering application of polymeric membranes for oily wastewater treatment.
    Keywords: chemical engineering, environmental engineering
    Electronic ISSN: 2054-5703
    Topics: Natural Sciences in General
    Published by Royal Society
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