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Sample records for actin-related protein arp

  1. Yeast Actin-Related Protein ARP6 Negatively Regulates Agrobacterium-Mediated Transformation of Yeast Cell.

    PubMed

    Luo, Yumei; Chen, Zikai; Zhu, Detu; Tu, Haitao; Pan, Shen Quan

    2015-01-01

    The yeasts, including Saccharomyces cerevisiae and Pichia pastoris, are single-cell eukaryotic organisms that can serve as models for human genetic diseases and hosts for large scale production of recombinant proteins in current biopharmaceutical industry. Thus, efficient genetic engineering tools for yeasts are of great research and economic values. Agrobacterium tumefaciens-mediated transformation (AMT) can transfer T-DNA into yeast cells as a method for genetic engineering. However, how the T-DNA is transferred into the yeast cells is not well established yet. Here our genetic screening of yeast knockout mutants identified a yeast actin-related protein ARP6 as a negative regulator of AMT. ARP6 is a critical member of the SWR1 chromatin remodeling complex (SWR-C); knocking out some other components of the complex also increased the transformation efficiency, suggesting that ARP6 might regulate AMT via SWR-C. Moreover, knockout of ARP6 led to disruption of microtubule integrity, higher uptake and degradation of virulence proteins, and increased DNA stability inside the cells, all of which resulted in enhanced transformation efficiency. Our findings have identified molecular and cellular mechanisms regulating AMT and a potential target for enhancing the transformation efficiency in yeast cells. PMID:26425545

  2. Yeast Actin-Related Protein ARP6 Negatively Regulates Agrobacterium-Mediated Transformation of Yeast Cell

    PubMed Central

    Luo, Yumei; Chen, Zikai; Zhu, Detu; Tu, Haitao; Pan, Shen Quan

    2015-01-01

    The yeasts, including Saccharomyces cerevisiae and Pichia pastoris, are single-cell eukaryotic organisms that can serve as models for human genetic diseases and hosts for large scale production of recombinant proteins in current biopharmaceutical industry. Thus, efficient genetic engineering tools for yeasts are of great research and economic values. Agrobacterium tumefaciens-mediated transformation (AMT) can transfer T-DNA into yeast cells as a method for genetic engineering. However, how the T-DNA is transferred into the yeast cells is not well established yet. Here our genetic screening of yeast knockout mutants identified a yeast actin-related protein ARP6 as a negative regulator of AMT. ARP6 is a critical member of the SWR1 chromatin remodeling complex (SWR-C); knocking out some other components of the complex also increased the transformation efficiency, suggesting that ARP6 might regulate AMT via SWR-C. Moreover, knockout of ARP6 led to disruption of microtubule integrity, higher uptake and degradation of virulence proteins, and increased DNA stability inside the cells, all of which resulted in enhanced transformation efficiency. Our findings have identified molecular and cellular mechanisms regulating AMT and a potential target for enhancing the transformation efficiency in yeast cells. PMID:26425545

  3. The human actin-related protein hArp5: Nucleo-cytoplasmic shuttling and involvement in DNA repair

    SciTech Connect

    Kitayama, Kumiko; Kamo, Mariko; Oma, Yukako; Matsuda, Ryo; Uchida, Takafumi; Ikura, Tsuyoshi; Tashiro, Satoshi; Ohyama, Takashi; Winsor, Barbara; Harata, Masahiko

    2009-01-15

    Certain actin-related proteins (Arps) of budding yeast are localized in the nucleus, and have essential roles as stoichiometric components of histone acetyltransferase (HAT) and chromatin remodeling complexes. On the other hand, identification of vertebrate nuclear Arps and their functional analyses are just beginning. We show that human Arp5 (hArp5) proteins are localized in the nucleus, and that arp5{delta} yeast cells are partially complemented by hArp5. Thus, hArp5 is a novel member of the nuclear Arps of vertebrates, which possess evolutionarily conserved functions from yeast to humans. We show here that hArp5 shuttles between the nucleus and the cytoplasm. Furthermore, after the induction of DNA double strand breaks (DSB), cell growth and the accumulation of phosphorylated histone H2AX ({gamma}-H2AX) are impaired by hArp5 depletion. Association of hArp5 with the hIno80 chromatin remodeling enzyme and decrease of chromatin-bound hIno80 by hArp5-depletion indicate that hArp5 may have a role in the recruitment of the hINO80 complex to chromatin. Overexpression of hArp5 and hIno80 enhanced {gamma}-H2AX accumulation. These observations suggest that hArp5 is involved in the process of DSB repair through the regulation of the chromatin remodelling machinery.

  4. The p150Glued component of the dynactin complex binds to both microtubules and the actin-related protein centractin (Arp-1).

    PubMed Central

    Waterman-Storer, C M; Karki, S; Holzbaur, E L

    1995-01-01

    p150Glued was first identified as a polypeptide that copurifies with cytoplasmic dynein, the minus-end-directed microtubule-based motor protein, and has more recently been shown to be present as a member of the oligomeric dynactin complex, which includes the actin-related protein centractin (Arp-1). Dynactin is thought to mediate dynein-driven vesicle motility, as well as nuclear transport, in lower eukaryotes. The mechanism by which dynactin may function in these cellular processes is unknown. To examine the role of the dynactin complex in vivo, we overexpressed the rat cDNA encoding p150Glued in Rat-2 fibroblasts. Overexpression of full-length, as well as C-terminal deletion, constructs resulted in the decoration of microtubules with the p150Glued polypeptides. This cellular evidence for microtubule association was corroborated by in vitro microtubule-binding assays. Amino acids 39-150 of p150Glued were determined to be sufficient for microtubule association. We also tested for a direct interaction between p150Glued and centractin. In vitro translated centractin was specifically retained by a p150Glued affinity column, and this interaction was blocked by a synthetic peptide which corresponds to a highly conserved motif from the C terminus of p150Glued. These results demonstrate that p150Glued, a protein implicated in cytoplasmic dynein-based microtubule motility, is capable of direct binding to both microtubules and centractin. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:7878030

  5. Sequence and comparative genomic analysis of actin-related proteins.

    PubMed

    Muller, Jean; Oma, Yukako; Vallar, Laurent; Friederich, Evelyne; Poch, Olivier; Winsor, Barbara

    2005-12-01

    Actin-related proteins (ARPs) are key players in cytoskeleton activities and nuclear functions. Two complexes, ARP2/3 and ARP1/11, also known as dynactin, are implicated in actin dynamics and in microtubule-based trafficking, respectively. ARP4 to ARP9 are components of many chromatin-modulating complexes. Conventional actins and ARPs codefine a large family of homologous proteins, the actin superfamily, with a tertiary structure known as the actin fold. Because ARPs and actin share high sequence conservation, clear family definition requires distinct features to easily and systematically identify each subfamily. In this study we performed an in depth sequence and comparative genomic analysis of ARP subfamilies. A high-quality multiple alignment of approximately 700 complete protein sequences homologous to actin, including 148 ARP sequences, allowed us to extend the ARP classification to new organisms. Sequence alignments revealed conserved residues, motifs, and inserted sequence signatures to define each ARP subfamily. These discriminative characteristics allowed us to develop ARPAnno (http://bips.u-strasbg.fr/ARPAnno), a new web server dedicated to the annotation of ARP sequences. Analyses of sequence conservation among actins and ARPs highlight part of the actin fold and suggest interactions between ARPs and actin-binding proteins. Finally, analysis of ARP distribution across eukaryotic phyla emphasizes the central importance of nuclear ARPs, particularly the multifunctional ARP4. PMID:16195354

  6. A mutation in the Cc.arp9 gene encoding a putative actin-related protein causes defects in fruiting initiation and asexual development in the agaricomycete Coprinopsis cinerea.

    PubMed

    Nakazawa, Takehito; Ando, Yuki; Hata, Takeshi; Nakahori, Kiyoshi

    2016-08-01

    Agaricomycetes exhibit a remarkable morphological differentiation from vegetative mycelia to huge fruiting bodies. To investigate the molecular mechanism underlying the fruiting body development, we have isolated and characterized many Coprinopsis cinerea mutant strains defective in fruiting initiation to date. Dikaryon formation in agaricomycetes, which is followed by fruiting development, is governed by the mating type loci, A and B. Recently, mutations in the Cc.snf5 gene, which encodes a putative component of the chromatin remodeling complex switch/sucrose non-fermentable (SWI/SNF), were shown to cause defects in A-regulated clamp cell morphogenesis, as well as in fruiting initiation. Here, we demonstrate that Cc.arp9, which encodes a putative actin-related protein associated with two chromatin remodeling complexes, SWI/SNF and remodels the structure of chromatin (RSC), is also essential for fruiting initiation. In contrast to Cc.snf5 mutants, Cc.arp9 mutants were not defective in clamp cell formation. The effects of mutations in Cc.arp9 and Cc.snf5 on oidia production and the transcriptional expression levels of clp1 and pcc1, which are under the control of the A gene, were also examined. These indicated that Cc.Snf5 is involved in A-regulated pathways, whereas Cc.Arp9 is not apparently. Cc.arp9/Cc.snf5 double-gene disruptants were generated and their phenotypes were analyzed, which suggested a complicated developmental regulation mechanism mediated by chromatin remodeling. PMID:26746642

  7. Arabidopsis contains ancient classes of differentially expressed actin-related protein genes.

    PubMed

    McKinney, Elizabeth Cohen; Kandasamy, Muthugapatti K; Meagher, Richard B

    2002-03-01

    Actin-related proteins (ARPs) share less than 60% amino acid sequence homology with conventional actins and have roles in diverse cytoskeletal processes in the cytoplasm and nucleus. The genome of Arabidopsis was explored for possible ARP gene family members. Eight potential ARP gene sequences were found dispersed on three of the five Arabidopsis chromosomes. AtARP2 and AtARP3 are protein orthologs of their similarly named counterparts in other kingdoms. AtARP4, AtARP5, and AtARP6 are orthologs of two classes of nuclear ARPs previously characterized in animals and fungi, BAF53s and ARP6s. AtARP7 and AtARP8 appear to be novel proteins that are not closely related to any known animal or fungal ARPs, and may be plant specific. The complex Arabidopsis ARP gene structures each contain from five to 20 exons. Expressed transcripts were identified and characterized for AtARP2 through AtARP8, but not for AtARP9, and transcripts representing two splice variants were found for AtARP8. The seven expressed genes are predicted to encode proteins ranging from 146 to 471 amino acids in length. Relative to conventional actin and the other ARPs, AtARP2 and AtARP3 transcripts are expressed at very low levels in all organs. AtARP5, AtARP6, and AtARP8 each have distinct transcript expression patterns in seedlings, roots, leaves, flowers, and siliques. Using isovariant-specific monoclonal antibodies, AtARP4 and AtARP7 proteins were shown to be most highly expressed in flowers. The likely involvement of plant ARPs in actin nucleation, branching of actin filaments, chromatin restructuring, and transcription are briefly discussed. PMID:11891255

  8. Two actin-related proteins are shared functional components of the chromatin-remodeling complexes RSC and SWI/SNF.

    PubMed

    Cairns, B R; Erdjument-Bromage, H; Tempst, P; Winston, F; Kornberg, R D

    1998-11-01

    The yeast Saccharomyces cerevisiae contains two related chromatin-remodeling complexes, RSC and SWI/SNF, which are shown to share the actin-related proteins Arp7 and Arp9. Depending on the genetic background tested, arp7 delta and arp9 delta mutants are either inviable or show greatly impaired growth and Swi-/Snf- mutant phenotypes. Unlike swi/snf mutants, viable arp7 delta or arp9 delta mutants have an Spt- phenotype, suggesting that RSC affects transcription. Temperature-sensitive mutations in ARP7 and ARP9 were isolated, and the amino acid changes support the structural relationship of Arp7 and Arp9 to actin. However, site-directed mutations predicted to impair ATP binding or hydrolysis did not detectably affect Arp7 or Arp9 function. Our results suggest that actin-related proteins perform important roles in chromatin-remodeling complexes by virtue of structural rather than enzymatic similarities to actin. PMID:9844636

  9. Structure of Actin-related protein 8 and its contribution to nucleosome binding

    PubMed Central

    Gerhold, Christian B.; Winkler, Duane D.; Lakomek, Kristina; Seifert, Florian U.; Fenn, Sebastian; Kessler, Brigitte; Witte, Gregor; Luger, Karolin; Hopfner, Karl-Peter

    2012-01-01

    Nuclear actin-related proteins (Arps) are subunits of several chromatin remodelers, but their molecular functions within these complexes are unclear. We report the crystal structure of the INO80 complex subunit Arp8 in its ATP-bound form. Human Arp8 has several insertions in the conserved actin fold that explain its inability to polymerize. Most remarkably, one insertion wraps over the active site cleft and appears to rigidify the domain architecture, while active site features shared with actin suggest an allosterically controlled ATPase activity. Quantitative binding studies with nucleosomes and histone complexes reveal that Arp8 and the Arp8–Arp4–actin-HSA sub-complex of INO80 strongly prefer nucleosomes and H3–H4 tetramers over H2A–H2B dimers, suggesting that Arp8 functions as a nucleosome recognition module. In contrast, Arp4 prefers free (H3–H4)2 over nucleosomes and may serve remodelers through binding to (dis)assembly intermediates in the remodeling reaction. PMID:22977180

  10. The actin family protein ARP6 contributes to the structure and the function of the nucleolus

    SciTech Connect

    Kitamura, Hiroshi; Matsumori, Haruka; Kalendova, Alzbeta; Hozak, Pavel; Goldberg, Ilya G.; Nakao, Mitsuyoshi; Saitoh, Noriko; Harata, Masahiko

    2015-08-21

    The actin family members, consisting of actin and actin-related proteins (ARPs), are essential components of chromatin remodeling complexes. ARP6, one of the nuclear ARPs, is part of the Snf-2-related CREB-binding protein activator protein (SRCAP) chromatin remodeling complex, which promotes the deposition of the histone variant H2A.Z into the chromatin. In this study, we showed that ARP6 influences the structure and the function of the nucleolus. ARP6 is localized in the central region of the nucleolus, and its knockdown induced a morphological change in the nucleolus. We also found that in the presence of high concentrations of glucose ARP6 contributed to the maintenance of active ribosomal DNA (rDNA) transcription by placing H2A.Z into the chromatin. In contrast, under starvation, ARP6 was required for cell survival through the repression of rDNA transcription independently of H2A.Z. These findings reveal novel pleiotropic roles for the actin family in nuclear organization and metabolic homeostasis. - Highlights: • ARP6, an actin related protein, is important for nucleolar function and structure. • A population of ARP6 is localized in the center of nucleolus. • Depletion of ARP6 resulted in aberrant shape of the nucleolus. • ARP6 maintains the active rDNA transcription under high glucose. • ARP6 is required for the repression of rDNA transcription under starvation.

  11. The Association of the Arabidopsis Actin-Related Protein2/3 Complex with Cell Membranes Is Linked to Its Assembly Status But Not Its Activation1[W][OA

    PubMed Central

    Kotchoni, Simeon O.; Zakharova, Taya; Mallery, Eileen L.; Le, Jie; El-Assal, Salah El-Din; Szymanski, Daniel B.

    2009-01-01

    In growing plant cells, the combined activities of the cytoskeleton, endomembrane, and cell wall biosynthetic systems organize the cytoplasm and define the architecture and growth properties of the cell. These biosynthetic machineries efficiently synthesize, deliver, and recycle the raw materials that support cell expansion. The precise roles of the actin cytoskeleton in these processes are unclear. Certainly, bundles of actin filaments position organelles and are a substrate for long-distance intracellular transport, but the functional linkages between dynamic actin filament arrays and the cell growth machinery are poorly understood. The Arabidopsis (Arabidopsis thaliana) “distorted group” mutants have defined protein complexes that appear to generate and convert small GTPase signals into an Actin-Related Protein2/3 (ARP2/3)-dependent actin filament nucleation response. However, direct biochemical knowledge about Arabidopsis ARP2/3 and its cellular distribution is lacking. In this paper, we provide biochemical evidence for a plant ARP2/3. The plant complex utilizes a conserved assembly mechanism. ARPC4 is the most critical core subunit that controls the assembly and steady-state levels of the complex. ARP2/3 in other systems is believed to be mostly a soluble complex that is locally recruited and activated. Unexpectedly, we find that Arabidopsis ARP2/3 interacts strongly with cell membranes. Membrane binding is linked to complex assembly status and not to the extent to which it is activated. Mutant analyses implicate ARP2 as an important subunit for membrane association. PMID:19801398

  12. The linker histone in Saccharomyces cerevisiae interacts with actin-related protein 4 and both regulate chromatin structure and cellular morphology.

    PubMed

    Georgieva, Milena; Staneva, Dessislava; Uzunova, Katya; Efremov, Toni; Balashev, Konstantin; Harata, Masahiko; Miloshev, George

    2015-02-01

    Chromatin structure promotes important epigenetic mechanisms that regulate cellular fate by organizing, preserving and controlling the way by which the genetic information works. Our understanding of chromatin and its functions is sparse and not yet well defined. The uncertainty comes from the complexity of chromatin and is induced by the existence of a large number of nuclear proteins that influence it. The intricate interaction among all these structural and functional nuclear proteins has been under extensive study in the recent years. Here, we show that Saccharomyces cerevisiae linker histone physically interacts with Arp4p (actin-related protein 4) which is a key subunit of three chromatin modifying complexes - INO80, SWR1 and NuA4. A single - point mutation in the actin - fold domain of Arp4p together with the knock-out of the gene for the linker histone in S. cerevisiae severely abrogates cellular and nuclear morphology and leads to complete disorganizing of the higher levels of chromatin organization. PMID:25542182

  13. Structure and Biochemical Properties of Fission Yeast Arp2/3 Complex Lacking the Arp2 Subunit

    SciTech Connect

    Nolen, B.; Pollard, T

    2008-01-01

    Arp2/3 (actin-related protein 2/3) complex is a seven-subunit complex that nucleates branched actin filaments in response to cellular signals. Nucleation-promoting factors such as WASp/Scar family proteins activate the complex by facilitating the activating conformational change and recruiting the first actin monomer for the daughter branch. Here we address the role of the Arp2 subunit in the function of Arp2/3 complex by isolating a version of the complex lacking Arp2 (Arp2? Arp2/3 complex) from fission yeast. An x-ray crystal structure of the ?Arp2 Arp2/3 complex showed that the rest of the complex is unperturbed by the loss of Arp2. However, the Arp2? Arp2/3 complex was inactive in actin nucleation assays, indicating that Arp2 is essential to form a branch. A fluorescence anisotropy assay showed that Arp2 does not contribute to the affinity of the complex for Wsp1-VCA, a Schizosaccharomyces pombe nucleation-promoting factor protein. Fluorescence resonance energy transfer experiments showed that the loss of Arp2 does not prevent VCA from recruiting an actin monomer to the complex. Truncation of the N terminus of ARPC5, the smallest subunit in the complex, increased the yield of Arp2? Arp2/3 complex during purification but did not compromise nucleation activity of the full Arp2/3 complex.

  14. A Novel Actin-Related Protein Is Associated with Daughter Cell Formation in Toxoplasma gondii▿ †

    PubMed Central

    Gordon, Jennifer L.; Beatty, Wandy L.; Sibley, L. David

    2008-01-01

    Cell division in Toxoplasma gondii occurs by an unusual budding mechanism termed endodyogeny, during which twin daughters are formed within the body of the mother cell. Cytokinesis begins with the coordinated assembly of the inner membrane complex (IMC), which surrounds the growing daughter cells. The IMC is compiled of both flattened membrane cisternae and subpellicular filaments composed of articulin-like proteins attached to underlying singlet microtubules. While proteins that comprise the elongating IMC have been described, little is known about its initial formation. Using Toxoplasma as a model system, we demonstrate that actin-like protein 1 (ALP1) is partially redistributed to the IMC at early stages in its formation. Immunoelectron microscopy localized ALP1 to a discrete region of the nuclear envelope, on transport vesicles, and on the nascent IMC of the daughter cells prior to the arrival of proteins such as IMC-1. The overexpression of ALP1 under the control of a strong constitutive promoter disrupted the formation of the daughter cell IMC, leading to delayed growth and defects in nuclear and apicoplast segregation. Collectively, these data suggest that ALP1 participates in the formation of daughter cell membranes during cell division in apicomplexan parasites. PMID:18408052

  15. Reduced Myelin Basic Protein and Actin-Related Gene Expression in Visual Cortex in Schizophrenia

    PubMed Central

    Matthews, Paul R.; Eastwood, Sharon L.; Harrison, Paul J.

    2012-01-01

    Most brain gene expression studies of schizophrenia have been conducted in the frontal cortex or hippocampus. The extent to which alterations occur in other cortical regions is not well established. We investigated primary visual cortex (Brodmann area 17) from the Stanley Neuropathology Consortium collection of tissue from 60 subjects with schizophrenia, bipolar disorder, major depression, or controls. We first carried out a preliminary array screen of pooled RNA, and then used RT-PCR to quantify five mRNAs which the array identified as differentially expressed in schizophrenia (myelin basic protein [MBP], myelin-oligodendrocyte glycoprotein [MOG], β-actin [ACTB], thymosin β-10 [TB10], and superior cervical ganglion-10 [SCG10]). Reduced mRNA levels were confirmed by RT-PCR for MBP, ACTB and TB10. The MBP reduction was limited to transcripts containing exon 2. ACTB and TB10 mRNAs were also decreased in bipolar disorder. None of the transcripts were altered in subjects with major depression. Reduced MBP mRNA in schizophrenia replicates findings in other brain regions and is consistent with oligodendrocyte involvement in the disorder. The decreases in expression of ACTB, and the actin-binding protein gene TB10, suggest changes in cytoskeletal organisation. The findings confirm that the primary visual cortex shows molecular alterations in schizophrenia and extend the evidence for a widespread, rather than focal, cortical pathophysiology. PMID:22675524

  16. Actin related protein complex subunit 1b controls sperm release, barrier integrity and cell division during adult rat spermatogenesis.

    PubMed

    Kumar, Anita; Dumasia, Kushaan; Deshpande, Sharvari; Gaonkar, Reshma; Balasinor, N H

    2016-08-01

    Actin remodeling is a vital process for signaling, movement and survival in all cells. In the testes, extensive actin reorganization occurs at spermatid-Sertoli cell junctions during sperm release (spermiation) and at inter Sertoli cell junctions during restructuring of the blood testis barrier (BTB). During spermiation, tubulobulbar complexes (TBCs), rich in branched actin networks, ensure recycling of spermatid-Sertoli cell junctional molecules. Similar recycling occurs during BTB restructuring around the same time as spermiation occurs. Actin related protein 2/3 complex is an essential actin nucleation and branching protein. One of its subunits, Arpc1b, was earlier found to be down-regulated in an estrogen-induced rat model of spermiation failure. Also, Arpc1b was found to be estrogen responsive through estrogen receptor beta in seminiferous tubule culture. Here, knockdown of Arpc1b by siRNA in adult rat testis led to defects in spermiation caused by failure in TBC formation. Knockdown also compromised BTB integrity and caused polarity defects of mature spermatids. Apart from these effects pertaining to Sertoli cells, Arpc1b reduction perturbed ability of germ cells to enter G2/M phase thus hindering cell division. In summary, Arpc1b, an estrogen responsive gene, is a regulator of spermiation, mature spermatid polarity, BTB integrity and cell division during adult spermatogenesis. PMID:27113856

  17. Visualizing Arp2/3 Complex Activation Mediated by Binding of ATP and WASp using Structural Mass Spectrometry

    SciTech Connect

    Kiselar,J.; Mahaffy, R.; Pollard, T.; Almo, S.; Chance, M.

    2007-01-01

    Actin-related protein (Arp) 2/3 complex nucleates new branches in actin filaments playing a key role in controlling eukaryotic cell motility. This process is tightly regulated by activating factors: ATP and WASp-family proteins. However, the mechanism of activation remains largely hypothetical. We used radiolytic protein footprinting with mass spectrometry in solution to probe the effects of nucleotide- and WASp-binding on Arp2/3. These results represent two significant advances in such footprinting approaches. First, Arp2/3 is the most complex macromolecular assembly yet examined; second, only a few picomoles of Arp2/3 was required for individual experiments. In terms of structural biology of Arp 2/3, we find that ATP binding induces conformational changes within Arp2/3 complex in Arp3 (localized in peptide segments 5-18, 212-225, and 318-327) and Arp2 (within peptide segment 300-316). These data are consistent with nucleotide docking within the nucleotide clefts of the actin-related proteins promoting closure of the cleft of the Arp3 subunit. However, ATP binding does not induce conformational changes in the other Arp subunits. Arp2/3 complex binds to WASp within the C subdomain at residue Met 474 and within the A subdomain to Trp 500. Our data suggest a bivalent attachment of WASp to Arp3 (within peptides 162-191 and 318-329) and Arp2 (within peptides 66-80 and 87-97). WASp-dependent protections from oxidation within peptides 54-65 and 80-91 of Arp3 and in peptides 300-316 of Arp2 suggest domain rearrangements of Arp2 and Arp3 resulting in a closed conformational state consistent with an 'actin-dimer' model for the active state.

  18. Collapsin Response Mediator Protein-1 Regulates Arp2/3-dependent Actin Assembly.

    PubMed

    Yu-Kemp, Hui-Chia; Brieher, William M

    2016-01-01

    Listeria monocytogenes is a bacterial parasite that uses host proteins to assemble an Arp2/3-dependent actin comet tail to power its movement through the host cell. Initiation of comet tail assembly is more efficient in cytosol than it is under defined conditions, indicating that unknown factors contribute to the reaction. We therefore fractionated cytosol and identified CRMP-1 as a factor that facilitates Arp2/3-dependent Listeria actin cloud formation in the presence of Arp2/3 and actin alone. It also scored as an important factor for Listeria actin comet tail formation in brain cytosol. CRMP-1 does not nucleate actin assembly on its own, nor does it directly activate the Arp2/3 complex. Rather, CRMP-1 scored as an auxiliary factor that promoted the ability of Listeria ActA protein to activate the Arp2/3 complex to trigger actin assembly. CRMP-1 is one member of a family of five related proteins that modulate cell motility in response to extracellular signals. Our results demonstrate an important role for CRMP-1 in Listeria actin comet tail formation and open the possibility that CRMP-1 controls cell motility by modulating Arp2/3 activation. PMID:26598519

  19. ox-LDL induces endothelial dysfunction by promoting Arp2/3 complex expression.

    PubMed

    Tang, Yao; Zhao, Jianting; Shen, Liming; Jin, Yiqi; Zhang, Zhixuan; Xu, Guoxiong; Huang, Xianchen

    2016-06-24

    Oxidized low-density lipoproteins (ox-LDL) play a critical role in endothelial injury including cytoskeleton reorganization, which is closely related to actin-related protein 2/3 (Arp2/3) complex. The aim of this study was to investigate the role of Arp2/3 complex in ox-LDL-induced endothelial dysfunction. In this study, we found that Arp2 and Arp3 expression was increased under atherosclerotic conditions both in ApoE-/- mice and in ox-LDL-stimulated human coronary artery endothelial cells (HCAECs). Arp2/3 complex inhibitor CK666 significantly reduced ox-LDL-induced ROS generation and cytoskeleton reorganization, and increased NO release in HCAECs. Pretreatment with LOX-1- but not CD36-blocking antibody markedly decreased ox-LDL-induced Arp2 and Arp3 expression. Moreover, Rac-1 siRNA remarkably suppressed ox-LDL-stimulated Arp2 and Arp3 expression. Additionally, CK666 reduced endothelial nitric oxide synthase (eNOS) expression and atherosclerotic lesions in ApoE-/- mice. Collectively, ox-LDL induces endothelial dysfunction by activating LOX-1/Rac-1 signaling and upregulating Arp2/3 complex expression. PMID:27181356

  20. Characterization of Two Classes of Small Molecule Inhibitors of Arp2/3 Complex

    SciTech Connect

    Nolen, B.; Tomasevic, N; Russell, A; Pierce, D; Jia, Z; McCormick, C; Hartman, J; Sakowicz, R; Pollard, T

    2009-01-01

    Polymerization of actin filaments directed by the actin-related protein (Arp)2/3 complex supports many types of cellular movements. However, questions remain regarding the relative contributions of Arp2/3 complex versus other mechanisms of actin filament nucleation to processes such as path finding by neuronal growth cones; this is because of the lack of simple methods to inhibit Arp2/3 complex reversibly in living cells. Here we describe two classes of small molecules that bind to different sites on the Arp2/3 complex and inhibit its ability to nucleate actin filaments. CK-0944636 binds between Arp2 and Arp3, where it appears to block movement of Arp2 and Arp3 into their active conformation. CK-0993548 inserts into the hydrophobic core of Arp3 and alters its conformation. Both classes of compounds inhibit formation of actin filament comet tails by Listeria and podosomes by monocytes. Two inhibitors with different mechanisms of action provide a powerful approach for studying the Arp2/3 complex in living cells.

  1. Structural and Biochemical Characterization of Two Binding Sites for Nucleation-promoting Factor WASp-VCA on Arp2/3 Complex

    SciTech Connect

    S Ti; C Jurgenson; B Nolen; T Pollard

    2011-12-31

    Actin-related protein (Arp) 2/3 complex mediates the formation of actin filament branches during endocytosis and at the leading edge of motile cells. The pathway of branch formation is ambiguous owing to uncertainty regarding the stoichiometry and location of VCA binding sites on Arp2/3 complex. Isothermal titration calorimetry showed that the CA motif from the C terminus of fission yeast WASP (Wsp1p) bound to fission yeast and bovine Arp2/3 complex with a stoichiometry of 2 to 1 and very different affinities for the two sites (K{sub d}s of 0.13 and 1.6 {micro}M for fission yeast Arp2/3 complex). Equilibrium binding, kinetic, and cross-linking experiments showed that (i) CA at high-affinity site 1 inhibited Arp2/3 complex binding to actin filaments, (ii) low-affinity site 2 had a higher affinity for CA when Arp2/3 complex was bound to actin filaments, and (iii) Arp2/3 complex had a much higher affinity for free CA than VCA cross-linked to an actin monomer. Crystal structures showed the C terminus of CA bound to the low-affinity site 2 on Arp3 of bovine Arp2/3 complex. The C helix is likely to bind to the barbed end groove of Arp3 in a position for VCA to deliver the first actin subunit to the daughter filament.

  2. A pathogenesis related-10 protein CaARP functions as aldo/keto reductase to scavenge cytotoxic aldehydes.

    PubMed

    Jain, Deepti; Khandal, Hitaishi; Khurana, Jitendra Paul; Chattopadhyay, Debasis

    2016-01-01

    Pathogenesis related-10 (PR-10) proteins are present as multigene family in most of the higher plants. The role of PR-10 proteins in plant is poorly understood. A sequence analysis revealed that a large number of PR-10 proteins possess conserved motifs found in aldo/keto reductases (AKRs) of yeast and fungi. We took three PR-10 proteins, CaARP from chickpea, ABR17 from pea and the major pollen allergen Bet v1 from silver birch as examples and showed that these purified recombinant proteins possessed AKR activity using various cytotoxic aldehydes including methylglyoxal and malondialdehyde as substrates and the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) as co-factor. Essential amino acids for this catalytic activity were identified by substitution with other amino acids. CaARP was able to discriminate between the reduced and oxidized forms of NADP independently of its catalytic activity and underwent structural change upon binding with NADPH. CaARP protein was preferentially localized in cytosol. When expressed in bacteria, yeast or plant, catalytically active variants of CaARP conferred tolerance to salinity, oxidative stress or cytotoxic aldehydes. CaARP-expressing plants showed lower lipid peroxidation product content in presence or absence of stress suggesting that the protein functions as a scavenger of cytotoxic aldehydes produced by metabolism and lipid peroxidation. Our result proposes a new biochemical property of a PR-10 protein. PMID:26577640

  3. Caveolin 1 (Cav-1) and actin-related protein 2/3 complex, subunit 1B (ARPC1B) expressions as prognostic indicators for oral squamous cell carcinoma (OSCC).

    PubMed

    Auzair, Lukman Bin Md; Vincent-Chong, Vui King; Ghani, Wan Maria Nabillah; Kallarakkal, Thomas George; Ramanathan, Anand; Lee, Chia Ee; Rahman, Zainal Ariff Abdul; Ismail, Siti Mazlipah; Abraham, Mannil Thomas; Zain, Rosnah Binti

    2016-07-01

    Caveolin-1 (Cav-1) and Actin-Related Protein 2/3 Complex, Subunit 1B (ARPC1B) have been implicated in various human cancers, yet its role in tumorigenesis remains controversial. Therefore, this study aims to determine the protein expression of these two genes in oral squamous cell carcinomas (OSCCs) and to evaluate the clinical and prognostic impact of these genes in OSCC. Protein expressions of these two genes were determined by immunohistochemistry technique. The association between Cav-1 and ARPC1B with clinico-pathological parameters was evaluated by Chi-square test (or Fisher exact test where appropriate). Correlation between the protein expressions of these 2 genes with survival was analyzed using Kaplan-Meier and Cox regression models. Cav-1 and ARPC1B were found to be significantly over-expressed in OSCC compared to normal oral mucosa (p = 0.002 and p = 0.033, respectively). Low level of ARPC1B protein expression showed a significant correlation with lymph node metastasis (LNM) (p = 0.010) and advanced tumor staging (p = 0.003). Kaplan-Meier survival analyses demonstrated that patients with over-expression of Cav-1 protein were associated with poor prognosis (p = 0.030). Adjusted multivariate Cox regression model revealed that over-expression of Cav-1 remained as an independent significant prognostic factor for OSCC (HRR = 2.700, 95 % CI 1.013-7.198, p = 0.047). This study demonstrated that low-expression of ARPC1B is significantly associated with LNM and advanced tumor staging whereas high expression of Cav-1 can be a prognostic indicator for poor prognosis in OSCC patients. PMID:26138391

  4. Signalling to actin assembly via the WASP (Wiskott-Aldrich syndrome protein)-family proteins and the Arp2/3 complex.

    PubMed Central

    Millard, Thomas H; Sharp, Stewart J; Machesky, Laura M

    2004-01-01

    The assembly of a branched network of actin filaments provides the mechanical propulsion that drives a range of dynamic cellular processes, including cell motility. The Arp2/3 complex is a crucial component of such filament networks. Arp2/3 nucleates new actin filaments while bound to existing filaments, thus creating a branched network. In recent years, a number of proteins that activate the filament nucleation activity of Arp2/3 have been identified, most notably the WASP (Wiskott-Aldrich syndrome protein) family. WASP-family proteins activate the Arp2/3 complex, and consequently stimulate actin assembly, in response to extracellular signals. Structural studies have provided a significant refinement in our understanding of the molecular detail of how the Arp2/3 complex nucleates actin filaments. There has also been much progress towards an understanding of the complicated signalling processes that regulate WASP-family proteins. In addition, the use of gene disruption in a number of organisms has led to new insights into the specific functions of individual WASP-family members. The present review will discuss the Arp2/3 complex and its regulators, in particular the WASP-family proteins. Emphasis will be placed on recent developments in the field that have furthered our understanding of actin dynamics and cell motility. PMID:15040784

  5. Role and structural mechanism of WASP-triggered conformational changes in branched actin filament nucleation by Arp2/3 complex.

    PubMed

    Rodnick-Smith, Max; Luan, Qing; Liu, Su-Ling; Nolen, Brad J

    2016-07-01

    The Arp2/3 (Actin-related proteins 2/3) complex is activated by WASP (Wiskott-Aldrich syndrome protein) family proteins to nucleate branched actin filaments that are important for cellular motility. WASP recruits actin monomers to the complex and stimulates movement of Arp2 and Arp3 into a "short-pitch" conformation that mimics the arrangement of actin subunits within filaments. The relative contribution of these functions in Arp2/3 complex activation and the mechanism by which WASP stimulates the conformational change have been unknown. We purified budding yeast Arp2/3 complex held in or near the short-pitch conformation by an engineered covalent cross-link to determine if the WASP-induced conformational change is sufficient for activity. Remarkably, cross-linked Arp2/3 complex bypasses the need for WASP in activation and is more active than WASP-activated Arp2/3 complex. These data indicate that stimulation of the short-pitch conformation is the critical activating function of WASP and that monomer delivery is not a fundamental requirement for nucleation but is a specific requirement for WASP-mediated activation. During activation, WASP limits nucleation rates by releasing slowly from nascent branches. The cross-linked complex is inhibited by WASP's CA region, even though CA potently stimulates cross-linking, suggesting that slow WASP detachment masks the activating potential of the short-pitch conformational switch. We use structure-based mutations and WASP-Arp fusion chimeras to determine how WASP stimulates movement toward the short-pitch conformation. Our data indicate that WASP displaces the autoinhibitory Arp3 C-terminal tail from a hydrophobic groove at Arp3's barbed end to destabilize the inactive state, providing a mechanism by which WASP stimulates the short-pitch conformation and activates Arp2/3 complex. PMID:27325766

  6. Proteomic Analysis Identifies an NADPH Oxidase 1 (Nox1)-Mediated Role for Actin-Related Protein 2/3 Complex Subunit 2 (ARPC2) in Promoting Smooth Muscle Cell Migration

    PubMed Central

    Al Ghouleh, Imad; Rodríguez, Andrés; Pagano, Patrick J.; Csányi, Gábor

    2013-01-01

    A variety of vascular pathologies, including hypertension, restenosis and atherosclerosis, are characterized by vascular smooth muscle cell (VSMC) hypertrophy and migration. NADPH oxidase 1 (Nox1) plays a pivotal role in these phenotypes via distinct downstream signaling. However, the mediators differentiating these distinct phenotypes and their precise role in vascular disease are still not clear. The present study was designed to identify novel targets of VSMC Nox1 signaling using 2D Differential In-Gel Electrophoresis and Mass Spectrometry (2D-DIGE/MS). VSMC treatment with scrambled (Scrmb) or Nox1 siRNA and incubation with the oxidant hydrogen peroxide (H2O2; 50 μM, 3 h) followed by 2D-DIGE/MS on cell lysates identified 10 target proteins. Among these proteins, actin-related protein 2/3 complex subunit 2 (ARPC2) with no previous link to Nox isozymes, H2O2, or other reactive oxygen species (ROS), was identified and postulated to play an intermediary role in VSMC migration. Western blot confirmed that Nox1 mediates H2O2-induced ARPC2 expression in VSMC. Treatment with a p38 MAPK inhibitor (SB203580) resulted in reduced ARPC2 expression in H2O2-treated VSMC. Additionally, wound-healing “scratch” assay confirmed that H2O2 stimulates VSMC migration via Nox1. Importantly, gene silencing of ARPC2 suppressed H2O2-stimulated VSMC migration. These results demonstrate for the first time that Nox1-mediated VSMC migration involves ARPC2 as a downstream signaling target. PMID:24152438

  7. A Rickettsia WASP-like protein activates the Arp2/3 complex and mediates actin-based motility.

    PubMed

    Jeng, Robert L; Goley, Erin D; D'Alessio, Joseph A; Chaga, Oleg Y; Svitkina, Tatyana M; Borisy, Gary G; Heinzen, Robert A; Welch, Matthew D

    2004-08-01

    Spotted fever group Rickettsia are obligate intracellular pathogens that exploit the host cell actin cytoskeleton to promote motility and cell-to-cell spread. Although other pathogens such as Listeria monocytogenes use an Arp2/3 complex-dependent nucleation mechanism to generate comet tails consisting of Y-branched filament arrays, Rickettsia polymerize tails consisting of unbranched filaments by a previously unknown mechanism. We identified genes in several Rickettsia species encoding proteins (termed RickA) with similarity to the WASP family of Arp2/3-complex activators. Rickettsia rickettsii RickA activated both the nucleation and Y-branching activities of the Arp2/3 complex like other WASP-family proteins, and was sufficient to direct the motility of microscopic beads in cell extracts. Actin tails generated by RickA-coated beads consisted of Y-branched filament networks. These data suggest that Rickettsia use an Arp2/3 complex-dependent actin-nucleation mechanism similar to that of other pathogens. We propose that additional Rickettsia or host factors reorganize the Y-branched networks into parallel arrays in a manner similar to a recently proposed model of filopodia formation. PMID:15236643

  8. PPP1R42, a PP1 binding protein, regulates centrosome dynamics in ARPE-19 cells

    PubMed Central

    DeVaul, Nicole; Wang, Rong; Sperry, Ann O.

    2013-01-01

    Background The centrosome is the primary site for microtubule nucleation in cells and orchestrates reorganization of the microtubule cytoskeleton during the cell cycle. The activities of the centrosome must be closely aligned with progression of the cell cycle; misregulation of centrosome separation and duplication is a hallmark of cancer. In a subset of cells, including the developing spermatid, the centrosome becomes specialized to form the basal body thereby supporting growth of the axoneme in morphogenesis of cilia and flagella, structures critical for signaling and motility. Mammalian spermatogenesis is an excellent model system to investigate the transformations in cellular architecture that accompany these changes including formation of the flagellum. We have previously identified a leucine rich repeat protein (PPP1R42) that contains a protein phosphatase-1 (PP1) binding site and translocates from the apical nucleus to the centrosome at the base of the flagellum during spermiogenesis. In this manuscript we examine localization and function of PPP1R42 in a ciliated epithelial cell model as a first step in understanding the role of this protein in centrosome function and flagellar formation. Results We demonstrate that PPP1R42 localizes to the basal body in ARPE-19 retinal epithelial cells. Colocalization and co-immunoprecipitation experiments further show that PPP1R42 interacts with γ-tubulin. Inhibition of PPP1R42 with small interfering RNAs (siRNAs) causes accumulation of centrosomes indicating premature centrosome separation. Importantly, the activity of two signaling molecules that regulate centrosome separation, PP1 phosphatase and NEK2 kinase, changes when PPP1R42 is inhibited: PP1 activity is reduced with a corresponding increase in NEK2 activity. Conclusions We have identified a role for the PP1-binding protein, PPP1R42, in centrosome separation in ciliated ARPE-19 cells. Our finding that inhibition of PPP1R42 expression increases the number of

  9. RasGRP3 regulates the migration of glioma cells via interaction with Arp3

    PubMed Central

    Lee, Hae Kyung; Finniss, Susan; Cazacu, Simona; Xiang, Cunli; Poisson, Laila M.; Blumberg, Peter M.; Brodie, Chaya

    2015-01-01

    Glioblastoma (GBM), the most aggressive primary brain tumors, are highly infiltrative. Although GBM express high Ras activity and Ras proteins have been implicated in gliomagenesis, Ras-activating mutations are not frequent in these tumors. RasGRP3, an important signaling protein responsive to diacylglycerol (DAG), increases Ras activation. Here, we examined the expression and functions of RasGRP3 in GBM and glioma cells. RasGRP3 expression was upregulated in GBM specimens and glioma stem cells compared with normal brains and neural stem cells, respectively. RasGRP3 activated Ras and Rap1 in glioma cells and increased cell migration and invasion partially via Ras activation. Using pull-down assay and mass spectroscopy we identified the actin-related protein, Arp3, as a novel interacting protein of RasGRP3. The interaction of RasGRP3 and Arp3 was validated by immunofluorescence staining and co-immunoprecipitation, and PMA, which activates RasGRP3 and induces its translocation to the peri-nuclear region, increased the association of Arp3 and RasGRP3. Arp3 was upregulated in GBM, regulated cell spreading and migration and its silencing partially decreased these effects of RasGRP3 in glioma cells. In summary, RasGRP3 acts as an important integrating signaling protein of the DAG and Ras signaling pathways and actin polymerization and represents an important therapeutic target in GBM. PMID:25682201

  10. Tobacco Arp3 is localized to actin-nucleating sites in vivo

    PubMed Central

    Maisch, Jan; Fišerová, Jindřiška; Fischer, Lukáš; Nick, Peter

    2009-01-01

    The polarity of actin is a central determinant of intracellular transport in plant cells. To visualize actin polarity in living plant cells, the tobacco homologue of the actin-related protein 3 (ARP3) was cloned and a fusion with the red fluorescent protein (RFP) was generated. Upon transient expression of these fusions in the tobacco cell line BY-2 (Nicotiana tabacum L. cv. Bright Yellow 2), punctate structures were observed near the nuclear envelope and in the cortical plasma. These dots could be shown to decorate actin filaments by expressing RFP–ARP3 in a marker line, where actin was tagged by GFP (green fluorescent protein)–FABD (fimbrin actin-binding domain 2). When actin filaments were disrupted by latrunculin B or by prolonged cold treatment, and subsequently allowed to recover, the actin filaments reformed from the RFP–ARP3 structures, that therefore represented actin nucleation sites. The intracellular distribution of these sites was followed during the formation of pluricellular files, and it was observed that the density of RFP–ARP3 increased in the apex of the polarized, terminal cells of a file, whereas it was equally distributed in the central cells of a file. These findings are interpreted in terms of position-dependent differences of actin organization. PMID:19129161

  11. Arabidopsis BRICK1/HSPC300 is an essential WAVE-complex subunit that selectively stabilizes the Arp2/3 activator SCAR2.

    PubMed

    Le, Jie; Mallery, Eileen L; Zhang, Chunhua; Brankle, Steven; Szymanski, Daniel B

    2006-05-01

    The actin cytoskeleton dynamically reorganizes the cytoplasm during cell morphogenesis. The actin-related protein (Arp)2/3 complex is a potent nucleator of actin filaments that controls a variety of endomembrane functions including the endocytic internalization of plasma membrane , vacuole biogenesis , plasma-membrane protrusion in crawling cells , and membrane trafficking from the Golgi . Therefore, Arp2/3 is an important signaling target during morphogenesis. The evolutionarily conserved Rac-WAVE-Arp2/3 pathway links actin filament nucleation to cell morphogenesis . WAVE translates Rac-GTP signals into Arp2/3 activation by regulating the stability and/or localization of the activator subunit Scar/WAVE . The WAVE complex includes Sra1/PIR121/CYFIP1, Nap1/NAP125, Abi-1/Abi-2, Brick1(Brk1)/HSPC300, and Scar/WAVE : Defining the in vivo function of each subunit is an important step toward understanding this complicated signaling pathway. Brk1/HSPC300 has been the most recalcitrant WAVE-complex protein and has no known function. In this paper, we report that Arabidopsis brick1 (brk1) is a member of the "distorted group" of trichome morphology mutants, a group that defines a WAVE-ARP2/3 morphogenesis pathway . In this paper we provide the first strong genetic and biochemical evidence that BRK1 is a critical WAVE-complex subunit that selectively stabilizes the Arp2/3 activator SCAR2. PMID:16584883

  12. Structure of a human beta-actin-related pseudogene which lacks intervening sequences.

    PubMed Central

    Moos, M; Gallwitz, D

    1982-01-01

    From a human genomic library we have isolated and sequenced a beta-actin-related pseudogene (Hbeta Ac-psi l) which is free of intervening sequences. Several nucleotide insertions and deletions and translational stop codons generated within the protein-coding region indicate that this gene is functionless. PMID:6296793

  13. Sublethal Photothermal Stimulation with a Micropulse Laser Induces Heat Shock Protein Expression in ARPE-19 Cells

    PubMed Central

    Inagaki, Keiji; Shuo, Takuya; Katakura, Kanae; Ebihara, Nobuyuki; Murakami, Akira; Ohkoshi, Kishiko

    2015-01-01

    Purpose/Aim of the Study. Subthreshold micropulse diode laser photocoagulation is an effective treatment for macular edema. The molecular mechanisms underlying treatment success are poorly understood. Therefore, we investigated the effects of sublethal laser energy doses on a single layer of densely cultured ARPE-19 cells as a model of the human retinal pigment epithelium (RPE). Materials and Methods. A single layer of densely cultured human ARPE-19 cells was perpendicularly irradiated with a micropulse diode laser. Nonirradiated cells served as controls. Sublethal laser energy was applied to form a photocoagulation-like area in the cultured cell layers. Hsp70 expression was evaluated using quantitative polymerase chain reaction and immunocytochemistry. Results. Photocoagulation-like areas were successfully created in cultured ARPE-19 cell layers using sublethal laser energy with our laser irradiation system. Hsp70 mRNA expression in cell layers was induced within 30 min of laser irradiation, peaking at 3 h after irradiation. This increase was dependent on the number of laser pulses. Hsp70 upregulation was not observed in untreated cell layers. Immunostaining indicated that Hsp70 expression occurred concentrically around laser irradiation sites and persisted for 24 h following irradiation. Conclusion. Sublethal photothermal stimulation with a micropulse laser may facilitate Hsp70 expression in the RPE without inducing cellular damage. PMID:26697211

  14. Capping Protein Increases the Rate of Actin-based Motility by Promoting Filament Nucleation by the Arp2/3 Complex

    PubMed Central

    Akin, Orkun; Mullins, R. Dyche

    2008-01-01

    Summary Capping protein is an integral component of Arp2/3-nucleated actin networks that drive amoeboid motility. Increasing the concentration of capping protein, which caps barbed ends of actin filaments and prevents elongation, increases the rate of actin-based motility in vivo and in vitro. We studied the synergy between capping protein and Arp2/3 using an in vitro actin-based motility system reconstituted from purified proteins. We find that capping protein increases the rate of motility by promoting more frequent filament nucleation by the Arp2/3 complex, and not by increasing the rate of filament elongation as previously suggested. One consequence of this coupling between capping and nucleation is that, while the rate of motility depends strongly on the concentration of capping protein and Arp2/3, the net rate of actin assembly is insensitive to changes in either factor. By reorganizing their architecture, dendritic actin networks harness the same assembly kinetics to drive different rates of motility. PMID:18510928

  15. Insights into the Influence of Nucleotides on Actin Family Proteins from Seven Structures of Arp2/3 Complex

    SciTech Connect

    Nolen,B.; Pollard, T.

    2007-01-01

    ATP is required for nucleation of actin filament branches by Arp2/3 complex, but the influence of ATP binding and hydrolysis are poorly understood. We determined crystal structures of bovine Arp2/3 complex cocrystalized with various bound adenine nucleotides and cations. Nucleotide binding favors closure of the nucleotide binding cleft of Arp3, but no large scale conformational changes in the complex. Thus, ATP binding does not directly activate Arp2/3 complex, but is part of a network of interactions that contribute to nucleation. We compared nucleotide-induced conformational changes of residues lining the cleft in Arp3 and actin structures to construct a movie depicting the proposed ATPase cycle for the actin family. Chemical crosslinking stabilized subdomain 1 of Arp2, revealing new electron density for 69 residues in this subdomain. Steric clashes with Arp3 appear to be responsible for intrinsic disorder of subdomains 1 and 2 of Arp2 in inactive Arp2/3 complex.

  16. The Expression of Bone Morphogenetic Protein 2 and Matrix Metalloproteinase 2 through Retinoic Acid Receptor Beta Induced by All-Trans Retinoic Acid in Cultured ARPE-19 Cells

    PubMed Central

    Gao, Zhenya; Huo, Lijun; Cui, Dongmei; Yang, Xiao; Zeng, Junwen

    2016-01-01

    Purpose All-trans retinoic acid (ATRA) plays an important role in ocular development. Previous studies found that retinoic acid could influence the metabolism of scleral remodeling by promoting retinal pigment epithelium (RPE) cells to secrete secondary signaling factors. The purpose of this study was to investigate whether retinoic acid affected secretion of bone morphogenetic protein 2 (BMP-2) and matrix metalloproteinase 2 (MMP-2) and to explore the signaling pathway of retinoic acid in cultured acute retinal pigment epithelial 19 (ARPE-19) cells. Methods The effects of ATRA (concentrations from 10−9 to 10−5 mol/l) on the expression of retinoic acid receptors (RARs) in ARPE-19 cells were examined at the mRNA and protein levels using reverse transcription-polymerase chain reaction (RT-PCR) and western blot assay, respectively. The effects of treating ARPE-19 cells with ATRA concentrations ranging from 10−9 to 10−5 mol/l for 24 h and 48 h or with 10-6mol/l ATRA at different times ranging from 6h to 72h were assessed using real-time quantitative PCR (qPCR) and enzyme-linked immunosorbent assay (ELISA). The contribution of RARβ-induced activation of ARPE-19 cells was confirmed using LE135, an antagonist of RARβ. Results RARβ mRNA levels significantly increased in the ARPE-19 cells treated with ATRA for 24h and 48h. These increases in RARβ mRNA levels were dose dependent (at concentrations of 10−9 to 10−5 mol/l) with a maximum effect observed at 10−6 mol/l. There were no significant changes in the mRNA levels of RARα and RARγ. Western blot assay revealed that RARβ protein levels were increased significantly in a time-dependent manner in ARPE-19 cells treated with 10−6 mol/l ATRA from 12 h to 72 h, with a marked increase observed at 24 h and 48 h. The upregulation of RARβ and the ATRA-induced secretion in ARPE-19 cells could be inhibited by the RARβ antagonist LE135. Conclusion ATRA induced upregulation of RARβ in ARPE-19 cells and stimulated

  17. Activation by Cdc42 and Pip2 of Wiskott-Aldrich Syndrome Protein (Wasp) Stimulates Actin Nucleation by Arp2/3 Complex

    PubMed Central

    Higgs, Henry N.; Pollard, Thomas D.

    2000-01-01

    We purified native WASp (Wiskott-Aldrich Syndrome protein) from bovine thymus and studied its ability to stimulate actin nucleation by Arp2/3 complex. WASp alone is inactive in the presence or absence of 0.5 μM GTP-Cdc42. Phosphatidylinositol 4,5 bisphosphate (PIP2) micelles allowed WASp to activate actin nucleation by Arp2/3 complex, and this was further enhanced twofold by GTP-Cdc42. Filaments nucleated by Arp2/3 complex and WASp in the presence of PIP2 and Cdc42 concentrated around lipid micelles and vesicles, providing that Cdc42 was GTP-bound and prenylated. Thus, the high concentration of WASp in neutrophils (9 μM) is dependent on interactions with both acidic lipids and GTP-Cdc42 to activate actin nucleation by Arp2/3 complex. The results also suggest that membrane binding increases the local concentrations of Cdc42 and WASp, favoring their interaction. PMID:10995437

  18. DISTORTED3/SCAR2 is a putative arabidopsis WAVE complex subunit that activates the Arp2/3 complex and is required for epidermal morphogenesis.

    PubMed

    Basu, Dipanwita; Le, Jie; El-Essal, Salah El-Din; Huang, Shanjin; Zhang, Chunhua; Mallery, Eileen L; Koliantz, Gregore; Staiger, Christopher J; Szymanski, Daniel B

    2005-02-01

    In a plant cell, a subset of actin filaments function as a scaffold that positions the endomembrane system and acts as a substrate on which organelle motility occurs. Other actin filament arrays appear to be more dynamic and reorganize in response to growth signals and external cues. The distorted group of trichome morphology mutants provides powerful genetic tools to study the control of actin filament nucleation in the context of morphogenesis. In this article, we report that DISTORTED3 (DIS3) encodes a plant-specific SCAR/WAVE homolog. Null alleles of DIS3, like those of other Arabidopsis thaliana WAVE and Actin-Related Protein (ARP) 2/3 subunit genes, cause trichome distortion, defects in cell-cell adhesion, and reduced hypocotyl growth in etiolated seedlings. DIS3 efficiently activates the actin filament nucleation and branching activity of vertebrate Arp2/3 and functions within a WAVE-ARP2/3 pathway in vivo. DIS3 may assemble into a WAVE complex via a physical interaction with a highly diverged Arabidopsis Abi-1-like bridging protein. These results demonstrate the utility of the Arabidopsis trichome system to understand how the WAVE and ARP2/3 complexes translate signaling inputs into a coordinated morphogenetic response. PMID:15659634

  19. The role of Arabidopsis SCAR genes in ARP2-ARP3-dependent cell morphogenesis.

    PubMed

    Uhrig, Joachim F; Mutondo, Moola; Zimmermann, Ilona; Deeks, Michael J; Machesky, Laura M; Thomas, Philipp; Uhrig, Silke; Rambke, Claudia; Hussey, Patrick J; Hülskamp, Martin

    2007-03-01

    The actin-nucleating ARP2-ARP3 complex controls cell shape in plants in many different cell types. Its activity is controlled by a multimeric complex containing BRK1 (also known as HSPC300), NAP1, SRA1, ABI and SCAR/WAVE. In this study, we focus on the function of the five putative SCAR homologues in Arabidopsis and we provide biochemical evidence that AtSCAR2 can activate the ARP2-ARP3 complex in vitro. Among the single mutants, mutations in only AtSCAR2 result in a subtle or weak phenotype similar to ARP2, ARP3 and other ;distorted' mutants. Double-mutant analysis revealed a redundancy with AtSCAR4. Systematic application of the yeast two-hybrid system and Bimolecular Fluorescence Complementation (BiFC) revealed a complex protein-interaction network between the ARP2-ARP3 complex and its genetically defined regulators. In addition to protein interactions known in other systems, we identified several new interactions, suggesting that SPIKE1 may be an integral component of the SCAR/WAVE complex and that SCAR proteins in plants might act as direct effectors of ROP GTPases. PMID:17267444

  20. Automated macromolecular model building for X-ray crystallography using ARP/wARP version 7

    PubMed Central

    Langer, Gerrit G; Cohen, Serge X; Lamzin, Victor S; Perrakis, Anastassis

    2008-01-01

    ARP/wARP is a software suite to build macromolecular models in X-ray crystallography electron density maps. Structural genomics initiatives and the study of complex macromolecular assemblies and membrane proteins all rely on advanced methods for 3D structure determination. ARP/wARP meets these needs by providing the tools to obtain a macromolecular model automatically, with a reproducible computational procedure. ARP/wARP 7.0 tackles several tasks: iterative protein model building including a high-level decision-making control module; fast construction of the secondary structure of a protein; building flexible loops in alternate conformations; fully automated placement of ligands, including a choice of the best fitting ligand from a “cocktail”; and finding ordered water molecules. All protocols are easy to handle by a non-expert user through a graphical user interface or a command line. The time required is typically a few minutes although iterative model building may take a few hours. PMID:18600222

  1. Expression of the ARPC4 Subunit of Human Arp2/3 Severely Affects Mycobacterium tuberculosis Growth and Suppresses Immunogenic Response in Murine Macrophages

    PubMed Central

    Ghosh, Anamika; Samuchiwal, Sachin K.; Bhalla, Kuhulika; Tharad, Megha; Kumar, Sushil; Prakash, Prem; Kumar, Purnima; Das, Gobardhan; Ranganathan, Anand

    2013-01-01

    Background The search for molecules against Mycobacterium tuberculosis is urgent. The mechanisms facilitating the intra-macrophage survival of Mycobacterium tuberculosis are as yet not entirely understood. However, there is evidence showing the involvement of host cell cytoskeleton in every step of establishment and persistence of mycobacterial infection. Methodology/Principal Findings Here we show that expression of ARPC4, a subunit of the Actin related protein 2/3 (Arp2/3) protein complex, severely affects the pathogen’s growth. TEM studies display shedding of the mycobacterial outer-coat. Furthermore, in infected macrophages, mycobacteria expressing ARPC4 were cleared off at a much faster rate, and were unable to mount a pro-inflammatory cytokine response. The translocation of ARPC4-expressing mycobacteria to the lysosome of the infected macrophage was also impaired. Additionally, the ARPC4 subunit was shown to interact with Rv1626, an essential secretory mycobacterial protein. Real-time PCR analysis showed that upon expression of ARPC4 in mycobacteria, Rv1626 expression is downregulated as much as six-fold. Rv1626 was found to also interact with mammalian cytoskeleton protein, Arp2/3, and enhance the rate of actin polymerization. Conclusions/Significance With crystal structures for Rv1626 and ARPC4 subunit already known, our finding lays out the effect of a novel molecule on mycobacteria, and represents a viable starting point for developing potent peptidomimetics. PMID:23894563

  2. rpS6 regulates blood-testis barrier dynamics through Arp3-mediated actin microfilament organization in rat sertoli cells. An in vitro study.

    PubMed

    Mok, Ka-Wai; Chen, Haiqi; Lee, Will M; Cheng, C Yan

    2015-05-01

    In the seminiferous epithelium of rat testes, preleptotene spermatocytes residing in the basal compartment are transported across the blood-testis barrier (BTB) to enter the adluminal compartment at stage VIII of the epithelial cycle. This process involves redistribution of tight junction (TJ) proteins via reorganization of actin cytoskeleton in Sertoli cells that serves as attachment site for adhesion protein complexes. Ribosomal protein S6 (rpS6), a downstream molecule of mTORC1 (mammalian target of rapamycin complex 1), participates in this process via a yet-to-be defined mechanism. Here, we constructed an rpS6 quadruple phosphomimetic mutant by converting Ser residues at 235, 236, 240, and 244 to Glu via site-directed mutagenesis, making this mutant constitutively active. When this rpS6 mutant was overexpressed in Sertoli cells cultured in vitro with an established TJ barrier mimicking the BTB in vivo, it perturbed the TJ permeability by down-regulating and redistributing TJ proteins at the cell-cell interface. These changes are mediated by a reorganization of actin microfilaments, which was triggered by a redistribution of activated actin-related protein 3 (Arp3) as well as changes in Arp3-neuronal Wiskott-Aldrich Syndrome protein (N-WASP) interaction. This in turn induced reorganization of actin microfilaments, converting them from a "bundled" to an "unbundled/branched" configuration, concomitant with a reduced actin bundling activity, thereby destabilizing the TJ-barrier function. These changes were mediated by Akt (transforming oncogene of v-akt), because an Akt knockdown by RNA interference was able to mimic the phenotypes of rpS6 mutant overexpression at the Sertoli cell BTB. In summary, this study illustrates a mechanism by which mTORC1 signal complex regulates BTB function through rpS6 downstream by modulating actin organization via the Arp2/3 complex, which may be applicable to other tissue barriers. PMID:25714812

  3. rpS6 Regulates Blood-Testis Barrier Dynamics Through Arp3-Mediated Actin Microfilament Organization in Rat Sertoli Cells. An In Vitro Study

    PubMed Central

    Mok, Ka-Wai; Chen, Haiqi; Lee, Will M.

    2015-01-01

    In the seminiferous epithelium of rat testes, preleptotene spermatocytes residing in the basal compartment are transported across the blood-testis barrier (BTB) to enter the adluminal compartment at stage VIII of the epithelial cycle. This process involves redistribution of tight junction (TJ) proteins via reorganization of actin cytoskeleton in Sertoli cells that serves as attachment site for adhesion protein complexes. Ribosomal protein S6 (rpS6), a downstream molecule of mTORC1 (mammalian target of rapamycin complex 1), participates in this process via a yet-to-be defined mechanism. Here, we constructed an rpS6 quadruple phosphomimetic mutant by converting Ser residues at 235, 236, 240, and 244 to Glu via site-directed mutagenesis, making this mutant constitutively active. When this rpS6 mutant was overexpressed in Sertoli cells cultured in vitro with an established TJ barrier mimicking the BTB in vivo, it perturbed the TJ permeability by down-regulating and redistributing TJ proteins at the cell-cell interface. These changes are mediated by a reorganization of actin microfilaments, which was triggered by a redistribution of activated actin-related protein 3 (Arp3) as well as changes in Arp3-neuronal Wiskott-Aldrich Syndrome protein (N-WASP) interaction. This in turn induced reorganization of actin microfilaments, converting them from a “bundled” to an “unbundled/branched” configuration, concomitant with a reduced actin bundling activity, thereby destabilizing the TJ-barrier function. These changes were mediated by Akt (transforming oncogene of v-akt), because an Akt knockdown by RNA interference was able to mimic the phenotypes of rpS6 mutant overexpression at the Sertoli cell BTB. In summary, this study illustrates a mechanism by which mTORC1 signal complex regulates BTB function through rpS6 downstream by modulating actin organization via the Arp2/3 complex, which may be applicable to other tissue barriers. PMID:25714812

  4. Platelet actin nodules are podosome-like structures dependent on Wiskott-Aldrich syndrome protein and ARP2/3 complex.

    PubMed

    Poulter, Natalie S; Pollitt, Alice Y; Davies, Amy; Malinova, Dessislava; Nash, Gerard B; Hannon, Mike J; Pikramenou, Zoe; Rappoport, Joshua Z; Hartwig, John H; Owen, Dylan M; Thrasher, Adrian J; Watson, Stephen P; Thomas, Steven G

    2015-01-01

    The actin nodule is a novel F-actin structure present in platelets during early spreading. However, only limited detail is known regarding nodule organization and function. Here we use electron microscopy, SIM and dSTORM super-resolution, and live-cell TIRF microscopy to characterize the structural organization and signalling pathways associated with nodule formation. Nodules are composed of up to four actin-rich structures linked together by actin bundles. They are enriched in the adhesion-related proteins talin and vinculin, have a central core of tyrosine phosphorylated proteins and are depleted of integrins at the plasma membrane. Nodule formation is dependent on Wiskott-Aldrich syndrome protein (WASp) and the ARP2/3 complex. WASp(-/-) mouse blood displays impaired platelet aggregate formation at arteriolar shear rates. We propose actin nodules are platelet podosome-related structures required for platelet-platelet interaction and their absence contributes to the bleeding diathesis of Wiskott-Aldrich syndrome. PMID:26028144

  5. Platelet actin nodules are podosome-like structures dependent on Wiskott–Aldrich syndrome protein and ARP2/3 complex

    PubMed Central

    Poulter, Natalie S.; Pollitt, Alice Y.; Davies, Amy; Malinova, Dessislava; Nash, Gerard B.; Hannon, Mike J.; Pikramenou, Zoe; Rappoport, Joshua Z.; Hartwig, John H.; Owen, Dylan M.; Thrasher, Adrian J.; Watson, Stephen P.; Thomas, Steven G.

    2015-01-01

    The actin nodule is a novel F-actin structure present in platelets during early spreading. However, only limited detail is known regarding nodule organization and function. Here we use electron microscopy, SIM and dSTORM super-resolution, and live-cell TIRF microscopy to characterize the structural organization and signalling pathways associated with nodule formation. Nodules are composed of up to four actin-rich structures linked together by actin bundles. They are enriched in the adhesion-related proteins talin and vinculin, have a central core of tyrosine phosphorylated proteins and are depleted of integrins at the plasma membrane. Nodule formation is dependent on Wiskott–Aldrich syndrome protein (WASp) and the ARP2/3 complex. WASp−/− mouse blood displays impaired platelet aggregate formation at arteriolar shear rates. We propose actin nodules are platelet podosome-related structures required for platelet–platelet interaction and their absence contributes to the bleeding diathesis of Wiskott–Aldrich syndrome. PMID:26028144

  6. ARP/wARP and molecular replacement: the next generation

    PubMed Central

    Cohen, Serge X.; Ben Jelloul, Marouane; Long, Fei; Vagin, Alexei; Knipscheer, Puck; Lebbink, Joyce; Sixma, Titia K.; Lamzin, Victor S.; Murshudov, Garib N.; Perrakis, Anastassis

    2008-01-01

    Automatic iterative model (re-)building, as implemented in ARP/wARP and its new control system flex-wARP, is particularly well suited to follow structure solution by molecular replacement. More than 100 molecular-replacement solutions automatically solved by the BALBES software were submitted to three standard protocols in flex-wARP and the results were compared with final models from the PDB. Standard metrics were gathered in a systematic way and enabled the drawing of statistical conclusions on the advantages of each protocol. Based on this analysis, an empirical estimator was proposed that predicts how good the final model produced by flex-wARP is likely to be based on the experimental data and the quality of the molecular-replacement solution. To introduce the differences between the three flex-wARP protocols (keeping the complete search model, converting it to atomic coordinates but ignoring atom identities or using the electron-density map calculated from the molecular-replacement solution), two examples are also discussed in detail, focusing on the evolution of the models during iterative rebuilding. This highlights the diversity of paths that the flex-wARP control system can employ to reach a nearly complete and accurate model while actually starting from the same initial information. PMID:18094467

  7. Identification and functional characterization of a novel low affinity aromatic-preferring amino acid transporter (arpAT). One of the few proteins silenced during primate evolution.

    PubMed

    Fernández, Esperanza; Torrents, David; Zorzano, Antonio; Palacín, Manuel; Chillarón, Josep

    2005-05-13

    We have identified in silico arpAT, a gene encoding a new member of the LSHAT family, and cloned it from kidney. Co-expression of arpAT with the heavy subunits rBAT or 4F2hc elicited a sodium-independent alanine transport activity in HeLa cells. L-tyrosine, l-3,4-dihydroxyphenylalanine (L-DOPA), L-glutamine, L-serine, L-cystine, and L-arginine were also transported. Kinetic and cis-inhibition studies showed a K(m) = 1.59 +/- 0.24 mM for L-alanine or IC50 in the millimolar range for most amino acids, except L-proline, glycine, anionic and D-amino acids, which were not inhibitory. L-DOPA and L-tyrosine were the most effective competitive inhibitors of L-alanine transport, with IC50 values of 272.2 +/- 57.1 and 716.3 +/- 112.4 microM, respectively. In the small intestine, arpAT mRNA was located at the enterocytes, in a decreasing gradient from the crypts to the tip of the villi. It was also expressed in neurons from different brain areas. Finally, we show that while the arpAT gene is conserved in rat, dog, and chicken, it has become silenced in humans and chimpanzee. Actually, it has been recently reported that it is one of the 33 recently inactivated genes in the human lineage. The evolutionary implications of the silencing process and the roles of arpAT in transport of L-DOPA in the brain and in aromatic amino acid absorption are discussed. PMID:15757906

  8. Assessment of automatic ligand building in ARP/wARP

    SciTech Connect

    Evrard, Guillaume X. Langer, Gerrit G.; Lamzin, Victor S.

    2007-01-01

    The performance of the ligand-building module of the ARP/wARP software suite is assessed through a large-scale test on known protein–ligand complexes. The results provide a detailed benchmark and guidelines for future improvements. The efficiency of the ligand-building module of ARP/wARP version 6.1 has been assessed through extensive tests on a large variety of protein–ligand complexes from the PDB, as available from the Uppsala Electron Density Server. Ligand building in ARP/wARP involves two main steps: automatic identification of the location of the ligand and the actual construction of its atomic model. The first step is most successful for large ligands. The second step, ligand construction, is more powerful with X-ray data at high resolution and ligands of small to medium size. Both steps are successful for ligands with low to moderate atomic displacement parameters. The results highlight the strengths and weaknesses of both the method of ligand building and the large-scale validation procedure and help to identify means of further improvement.

  9. Presence of Arp Specifically Contributes to Joint Tissue Edema Associated with Early-Onset Lyme Arthritis

    PubMed Central

    Hove, Petronella R.; Haldorson, Gary J.; Magunda, Forgivemore

    2014-01-01

    Antiserum to the Borrelia burgdorferi arthritis-related protein, Arp, has been shown to prevent or reduce arthritis in immunodeficient mice. To directly investigate the requirement for this lipoprotein in the generation of Lyme arthritis, we utilized targeted deletion to generate a B. burgdorferi clone that lacked only the arp gene locus. Infection of Lyme disease-susceptible C3H/HeN mice with the arp deletion mutant demonstrated significantly reduced tibiotarsal joint swelling during the first 6 weeks of infection compared to a wild-type control. The severity of joint swelling was restored to wild-type levels in mice infected with an arp mutant clone complemented in cis. Interestingly, the reduced swelling of joint tissues exhibited by mice infected with the arp deletion mutant did not directly correspond to reduced underlying arthritis. Histopathology data at 2 weeks postinfection showed some reduction in arthritis severity caused by the arp mutant clone; however, by 8 weeks, no significant difference was observed between joint tissues infected by the wild-type or arp mutant clones. The spirochete load in the joint tissues of mice infected with the arp mutant was found to be greater than that exhibited by the wild-type control. Our findings demonstrate that this lipoprotein contributes to the generation of early-onset joint swelling and suggests that arp expression has a negative secondary effect on total spirochete numbers in joint tissues. PMID:24101694

  10. Coronin 1B antagonizes Cortactin and remodels Arp2/3-containing actin branches in lamellipodia

    PubMed Central

    Cai, Liang; Makhov, Alexander M.; Schafer, Dorothy A.; Bear, James E.

    2008-01-01

    Summary The dendritic actin network generated by Arp2/3 complex in lamellipodia underlies formation of protrusions, directional sensing and migration. While the generation of this network is well studied, the mechanisms regulating network disassembly are poorly understood. We report that Coronin 1B disassembles Arp2/3-containing actin filament branches by inducing Arp2/3 dissociation. This activity is antagonized by Cortactin, a filament branch stabilizer. Consistent with this biochemical competition, depletion of both proteins partially rescues defects in lamellipodial dynamics observed upon depletion of either protein alone. Coronin 1B targets actin branches in a manner that is mutually exclusive with Arp2/3 complex and alters the branch angle. We conclude that Coronin 1B replaces Arp2/3 complex at actin filament branches as the dendritic network matures and drives the turnover of branched actin networks. PMID:18775315

  11. Color maps of Arp 146

    NASA Technical Reports Server (NTRS)

    Schultz, A. B.; Spight, L. D.; Colegrove, P. T.; Disanti, M. A.; Fink, U.

    1990-01-01

    Four color maps of Arp 146 are given. The structure and color of the ring galaxy and its companion show evidence of a bridge of material between the companion and the remnant nucleus of the original galaxy now forming the ring. Broad band spatial coverage clearly defines regions of starburst occurrence.

  12. A Novel Graphene Oxide-Based Protein Interaction Measurement Using Atomic Force Microscopy.

    PubMed

    Han, Sung-Woong; Morita, Kyohei; Adachi, Taiji

    2015-02-01

    Graphene oxide (GO) is a promising material for biological applications because of its excellent physical/chemical properties such as aqueous processability, amphiphilicity, and surface functionalizability. Here we introduce a new biological application of GO, a novel GO-based technique for probing protein interactions using atomic force microscopy (AFM). GO sheets were intercalated between the protein-modified AFM probe and the polymer substrate in order to reduce the non-specific adhesion force observed during single-molecule force spectroscopy (SMFS). In this study, we used SMFS to probe the interaction of the actin filament and actin-related protein 2/3 complex (Arp2/3), an actin-binding protein. Our results confirm that the GO sheet reduces nonspecific adhesion of the probe to the substrate. Using the GO-based technique, we succeeded in estimating the dissociation constant of the actin filament-binding protein interaction. PMID:26353630

  13. Arp2/3 complex-deficient mouse fibroblasts are viable and have normal leading-edge actin structure and function

    PubMed Central

    Di Nardo, Alessia; Cicchetti, Gregor; Falet, Hervé; Hartwig, John H.; Stossel, Thomas P.; Kwiatkowski, David J.

    2005-01-01

    RNA interference silencing of up to 90% of Arp3 protein expression, a major subunit of the Arp2/3 complex, proportionately decreases the intracellular motility of Listeria monocytogenes and actin nucleation activity ascribable to the Arp2/3 complex in mouse embryonic fibroblasts. However, the Arp2/3-deficient cells exhibit unimpaired lamellipodial actin network structure, translational locomotion, spreading, actin assembly, and ruffling responses. In addition, Arp3-silenced cells expressing neural Wiskott-Aldrich syndrome protein-derived peptides that inhibit Arp2/3 complex function in wild-type cells retained normal PDGF-induced ruffling. The Arp2/3 complex can be dispensable for leading-edge actin remodeling. PMID:16254049

  14. Identification of an ATP-controlled allosteric switch that controls actin filament nucleation by Arp2/3 complex

    PubMed Central

    Rodnick-Smith, Max; Liu, Su-Ling; Balzer, Connor J.; Luan, Qing; Nolen, Brad J.

    2016-01-01

    Nucleation of branched actin filaments by Arp2/3 complex is tightly regulated to control actin assembly in cells. Arp2/3 complex activation involves conformational changes brought about by ATP, Nucleation Promoting Factor (NPF) proteins, actin filaments and NPF-recruited actin monomers. To understand how these factors promote activation, we must first understand how the complex is held inactive in their absence. Here we demonstrate that the Arp3 C-terminal tail is a structural switch that prevents Arp2/3 complex from adopting an active conformation. The interaction between the tail and a hydrophobic groove in Arp3 blocks movement of Arp2 and Arp3 into an activated filament-like (short pitch) conformation. Our data indicate ATP binding destabilizes this interaction via an allosteric link between the Arp3 nucleotide cleft and the hydrophobic groove, thereby promoting the short-pitch conformation. Our results help explain how Arp2/3 complex is locked in an inactive state without activators and how autoinhibition is relieved. PMID:27417392

  15. Identification of an ATP-controlled allosteric switch that controls actin filament nucleation by Arp2/3 complex.

    PubMed

    Rodnick-Smith, Max; Liu, Su-Ling; Balzer, Connor J; Luan, Qing; Nolen, Brad J

    2016-01-01

    Nucleation of branched actin filaments by Arp2/3 complex is tightly regulated to control actin assembly in cells. Arp2/3 complex activation involves conformational changes brought about by ATP, Nucleation Promoting Factor (NPF) proteins, actin filaments and NPF-recruited actin monomers. To understand how these factors promote activation, we must first understand how the complex is held inactive in their absence. Here we demonstrate that the Arp3 C-terminal tail is a structural switch that prevents Arp2/3 complex from adopting an active conformation. The interaction between the tail and a hydrophobic groove in Arp3 blocks movement of Arp2 and Arp3 into an activated filament-like (short pitch) conformation. Our data indicate ATP binding destabilizes this interaction via an allosteric link between the Arp3 nucleotide cleft and the hydrophobic groove, thereby promoting the short-pitch conformation. Our results help explain how Arp2/3 complex is locked in an inactive state without activators and how autoinhibition is relieved. PMID:27417392

  16. ARPES investigation of deeply underdoped BISCO 2212

    NASA Astrophysics Data System (ADS)

    Tanaka, K.; Lee, W. S.; Lu, D. H.; Fujii, T.; Fujimori, A.; Hussain, Z.; Shen, Z. X.

    2006-03-01

    We present ARPES results from deeply underdoped BISCO 2212 with Tc ranging from 30 to 50 K. The improved sample quality with Y subsitution enables the detection of much sharper spectral features. We uncovered experimental evidence for two distinct energy gaps in these deeply underdoped samples. The theoretical implications of these findings will de discussed in conjunction with ARPES and RAMAN data.

  17. Tropomyosin Promotes Lamellipodial Persistence by Collaborating with Arp2/3 at the Leading Edge.

    PubMed

    Brayford, Simon; Bryce, Nicole S; Schevzov, Galina; Haynes, Elizabeth M; Bear, James E; Hardeman, Edna C; Gunning, Peter W

    2016-05-23

    At the leading edge of migrating cells, protrusion of the lamellipodium is driven by Arp2/3-mediated polymerization of actin filaments [1]. This dense, branched actin network is promoted and stabilized by cortactin [2, 3]. In order to drive filament turnover, Arp2/3 networks are remodeled by proteins such as GMF, which blocks the actin-Arp2/3 interaction [4, 5], and coronin 1B, which acts by directing SSH1L to the lamellipodium where it activates the actin-severing protein cofilin [6, 7]. It has been shown in vitro that cofilin-mediated severing of Arp2/3 actin networks results in the generation of new pointed ends to which the actin-stabilizing protein tropomyosin (Tpm) can bind [8]. The presence of Tpm in lamellipodia, however, is disputed in the literature [9-19]. Here, we report that the Tpm isoforms 1.8/9 are enriched in the lamellipodium of fibroblasts as detected with a novel isoform-specific monoclonal antibody. RNAi-mediated silencing of Tpm1.8/9 led to an increase of Arp2/3 accumulation at the cell periphery and a decrease in the persistence of lamellipodia and cell motility, a phenotype consistent with cortactin- and coronin 1B-deficient cells [2, 7]. In the absence of coronin 1B or cofilin, Tpm1.8/9 protein levels are reduced while, conversely, inhibition of Arp2/3 with CK666 leads to an increase in Tpm1.8/9 protein. These findings establish a novel regulatory mechanism within the lamellipodium whereby Tpm collaborates with Arp2/3 to promote lamellipodial-based cell migration. PMID:27112294

  18. Applications of Laser and Synchrotron Based ARPES to Photocathode Research

    SciTech Connect

    Rameau J.; Smedley J.; Muller, E.; Kidd, T.; Johnson, P.; Allen, P.; Carr, L.; Valla, T.

    2010-10-12

    Laser angle resolved photoelectron spectroscopy (ARPES) provides unique information about angle and energy distribution of photoelectrons. Laser ARPES gives unique insight into how NEA materials work. ARPES combined with some ancillary measurements gives a very complete picture of system electronic physics. For H:C[100] there is now a clear program for engineering as well as development analogous systems. ARPES well suited for identifying 'ideal' photocathodes with intrinsically low emittance and high QE.

  19. Structure, Subunit Topology, and Actin-binding Activity of the Arp2/3 Complex from Acanthamoeba

    PubMed Central

    Mullins, R. Dyche; Stafford, Walter F.; Pollard, Thomas D.

    1997-01-01

    The Arp2/3 complex, first isolated from Acanthamoeba castellani by affinity chromatography on profilin, consists of seven polypeptides; two actinrelated proteins, Arp2 and Arp3; and five apparently novel proteins, p40, p35, p19, p18, and p14 (Machesky et al., 1994). The complex is homogeneous by hydrodynamic criteria with a Stokes' radius of 5.3 nm by gel filtration, sedimentation coefficient of 8.7 S, and molecular mass of 197 kD by analytical ultracentrifugation. The stoichiometry of the subunits is 1:1:1:1:1:1:1, indicating the purified complex contains one copy each of seven polypeptides. In electron micrographs, the complex has a bilobed or horseshoe shape with outer dimensions of ∼13 × 10 nm, and mathematical models of such a shape and size are consistent with the measured hydrodynamic properties. Chemical cross-linking with a battery of cross-linkers of different spacer arm lengths and chemical reactivities identify the following nearest neighbors within the complex: Arp2 and p40; Arp2 and p35; Arp3 and p35; Arp3 and either p18 or p19; and p19 and p14. By fluorescent antibody staining with anti-p40 and -p35, the complex is concentrated in the cortex of the ameba, especially in linear structures, possibly actin filament bundles, that lie perpendicular to the leading edge. Purified Arp2/3 complex binds actin filaments with a Kd of 2.3 μM and a stoichiometry of approximately one complex molecule per actin monomer. In electron micrographs of negatively stained samples, Arp2/3 complex decorates the sides of actin filaments. EDC/NHS cross-links actin to Arp3, p35, and a low molecular weight subunit, p19, p18, or p14. We propose structural and topological models for the Arp2/3 complex and suggest that affinity for actin filaments accounts for the localization of complex subunits to actinrich regions of Acanthamoeba. PMID:9015304

  20. Actin and Arp2/3 localize at the centrosome of interphase cells

    SciTech Connect

    Hubert, Thomas; Vandekerckhove, Joel; Gettemans, Jan

    2011-01-07

    Research highlights: {yields} Actin was detected at the centrosome with the anti-actin antibody 1C7 that recognizes antiparallel ('lower dimer') actin dimers. {yields} Centrosomal actin was found in interphase but not mitotic MDA-MB-231 cells. {yields} Neither the anti-actin antibody C4 that binds to globular, monomer actin, nor the anti-actin antibody 2G2 that recognizes the nuclear conformation of actin detect actin at the centrosome. {yields} The Arp2/3 complex transiently localizes at the pericentriolar matrix but not at the centrioles of interphase HEK 293T cells. -- Abstract: Although many actin binding proteins such as cortactin and the Arp2/3 activator WASH localize at the centrosome, the presence and conformation of actin at the centrosome has remained elusive. Here, we report the localization of actin at the centrosome in interphase but not in mitotic MDA-MB-231 cells. Centrosomal actin was detected with the anti-actin antibody 1C7 that recognizes antiparallel ('lower dimer') actin dimers. In addition, we report the transient presence of the Arp2/3 complex at the pericentriolar matrix but not at the centrioles of interphase HEK 293T cells. Overexpression of an Arp2/3 component resulted in expansion of the pericentriolar matrix and selective accumulation of the Arp2/3 component in the pericentriolar matrix. Altogether, we hypothesize that the centrosome transiently recruits Arp2/3 to perform processes such as centrosome separation prior to mitotic entry, whereas the observed constitutive centrosomal actin staining in interphase cells reinforces the current model of actin-based centrosome reorientation toward the leading edge in migrating cells.

  1. The Arp Ring: Galactic or extragalactic?

    NASA Technical Reports Server (NTRS)

    Abolins, J. A.; Rice, W. L.

    1987-01-01

    The Arp Ring is a faint, loop-like structure around the northern end of M81 which becomes apparent only on deep optical photographs of the galaxy. The nature of the Ring and its proximity to M81 are uncertain. Is it simply foreground structure, part of this galaxy, or is it within the M81 system? Infrared Astronomy Satellite (IRAS) maps of the region show a far-infrared counterpart of the Ring. The infrared data are compared with previous optical and radio observations to try to ascertain its physical nature. The poor correlation found between the common infrared/optical structure and the distribution of extragalactic neutral hydrogen, and the fact that its infrared properties are indistinguishable from those of nearby galactic cirrus, imply that the Arp Ring is simply a ring structure in the galactic cirrus.

  2. Repression by ARP-1 sensitizes apolipoprotein AI gene responsiveness to RXR alpha and retinoic acid.

    PubMed Central

    Widom, R L; Rhee, M; Karathanasis, S K

    1992-01-01

    The gene coding for apolipoprotein AI (apoAI), a lipid binding protein involved in the transport of cholesterol and other lipids in the plasma, is expressed in mammals predominantly in the liver and the intestine. Liver-specific expression is controlled by synergistic interactions between transcription factors bound to three separate sites, sites A (-214 to -192), B (-169 to -146), and C (-134 to -119), within a powerful liver-specific enhancer located between nucleotides -222 and -110 upstream of the apoAI gene transcription start site (+1). Previous studies in our laboratory have shown that ARP-1, a member of the nuclear receptor superfamily whose ligand is unknown (orphan receptor), binds to site A and represses transcription of the apoAI gene in liver cells. In a more recent series of experiments, we found that site A is a retinoic acid (RA) response element that responds preferentially to the recently identified RA-responsive receptor RXR alpha over the previously characterized RA receptors RAR alpha and RAR beta. In this study we investigated the combined effects of ARP-1 and RXR alpha on apoAI gene expression in liver cells. Transient transfection assays showed that site A is necessary and sufficient for RXR alpha-mediated transactivation of the apoAI gene basal promoter in human hepatoma HepG2 cells in the presence of RA and that this transactivation is abolished by increasing amounts of cotransfected ARP-1. Electrophoretic mobility shift assays and subsequent Scatchard analysis of the data revealed that ARP-1 and RXR alpha bind to site A with similar affinities. These assays also revealed that ARP-1 and RXR alpha bind to site A as heterodimers with an affinity approximately 10 times greater than that of either ARP-1 or RXR alpha alone. Further transfection assays in HepG2 cells, using as a reporter a construct containing the apoAI gene basal promoter and its upstream regulatory elements (including site A) in their natural context, revealed that RXR alpha

  3. WAVE binds Ena/VASP for enhanced Arp2/3 complex–based actin assembly

    PubMed Central

    Havrylenko, Svitlana; Noguera, Philippe; Abou-Ghali, Majdouline; Manzi, John; Faqir, Fahima; Lamora, Audrey; Guérin, Christophe; Blanchoin, Laurent; Plastino, Julie

    2015-01-01

    The WAVE complex is the main activator of the Arp2/3 complex for actin filament nucleation and assembly in the lamellipodia of moving cells. Other important players in lamellipodial protrusion are Ena/VASP proteins, which enhance actin filament elongation. Here we examine the molecular coordination between the nucleating activity of the Arp2/3 complex and the elongating activity of Ena/VASP proteins for the formation of actin networks. Using an in vitro bead motility assay, we show that WAVE directly binds VASP, resulting in an increase in Arp2/3 complex–based actin assembly. We show that this interaction is important in vivo as well, for the formation of lamellipodia during the ventral enclosure event of Caenorhabditis elegans embryogenesis. Ena/VASP's ability to bind F-actin and profilin-complexed G-actin are important for its effect, whereas Ena/VASP tetramerization is not necessary. Our data are consistent with the idea that binding of Ena/VASP to WAVE potentiates Arp2/3 complex activity and lamellipodial actin assembly. PMID:25355952

  4. Robotic Reverberation Mapping of Arp 151

    NASA Astrophysics Data System (ADS)

    Valenti, S.; Sand, D. J.; Barth, A. J.; Horne, K.; Treu, T.; Raganit, L.; Boroson, T.; Crawford, S.; Pancoast, A.; Pei, L.; Romero-Colmenero, E.; Villforth, C.; Winkler, H.

    2015-11-01

    We present the first results from the Las Cumbres Observatory Global Telescope (LCOGT) Network's Active Galactic Nuclei (AGNs) Key Project, a large program devoted to using the robotic resources of LCOGT to perform time domain studies of active galaxies. We monitored the Seyfert 1 galaxy Arp 151 (Mrk 40) for ∼200 days with robotic imagers and with the FLOYDS robotic spectrograph at Faulkes Telescope North. Arp 151 was highly variable during this campaign, with V-band light curve variations of ∼0.3 mag and Hβ flux changing by a factor of ∼3. We measure robust time lags between the V-band continuum and the Hα, Hβ, and Hγ emission lines, with {τ }{cen}={13.89}-1.41+1.39, {7.52}-1.06+1.43, and {7.40}-1.32+1.50 days, respectively. The lag for the He iiλ4686 emission line is unresolved. We measure a velocity-resolved lag for the Hβ line, which is clearly asymmetric with higher lags on the blue wing of the line that decline to the red, possibly indicative of radial inflow, and is similar in morphology to past observations of the Hβ transfer function shape. Assuming a virialization factor of f = 5.5, we estimate a black hole mass of {M}{BH}={6.2}-1.2+1.4 × 106 M⊙, also consistent with past measurements for this object. These results represent the first step to demonstrate the powerful robotic capabilities of LCOGT for long-term AGN time domain campaigns that human intensive programs cannot easily accomplish. Arp 151 is now one of just a few AGNs where the virial product is known to remain constant against substantial changes in Hβ lag and luminosity.

  5. ARPES studies of van der Waals heterostructure

    NASA Astrophysics Data System (ADS)

    Wang, Eryin; Lu, Xiaobo; Chen, Guorui; Fedorov, Alexei V.; Zhang, Yuanbo; Zhang, Guangyu; Zhou, Shuyun

    Van der Waals heterostructures are a novel class of ``materials by design'' which are formed by stacking different two-dimensional crystals together via van der Waals interaction. The periodic potential by the Moir é superlattice can be used as a control knob for tuning the electronic properties of two dimensional materials and can induce various novel quantum phenomena. Here we report direct electronic structure studies the of a model van der Waals heterostructure using angle-resolved photoemission spectroscopy (ARPES). This work is supported by the National Natural Science Foundation of China and Ministry of Education of China.

  6. Functional domains of the human orphan receptor ARP-1/COUP-TFII involved in active repression and transrepression.

    PubMed

    Achatz, G; Hölzl, B; Speckmayer, R; Hauser, C; Sandhofer, F; Paulweber, B

    1997-09-01

    The orphan receptor ARP-1/COUP-TFII, a member of the chicken ovalbumin upstream promoter transcription factor (COUP-TF) subfamily of nuclear receptors, strongly represses transcriptional activity of numerous genes, including several apolipoprotein-encoding genes. Recently it has been demonstrated that the mechanism by which COUP-TFs reduce transcriptional activity involves active repression and transrepression. To map the domains of ARP-1/COUP-TFII required for repressor activity, a detailed deletion analysis of the protein was performed. Chimeric proteins in which various segments of the ARP-1/COUP-TFII carboxy terminus were fused to the GAL4 DNA binding domain were used to characterize its active repression domain. The smallest segment confering active repressor activity to a heterologous DNA binding domain was found to comprise residues 210 to 414. This domain encompasses the region of ARP-1/COUP-TFII corresponding to helices 3 to 12 in the recently published crystal structure of other members of the nuclear receptor superfamily. It includes the AF-2 AD core domain formed by helix 12 but not the hinge region, which is essential for interaction with a corepressor in the case of the thyroid hormone and retinoic acid receptor. Attachment of the nuclear localization signal from the simian virus 40 large T antigen (Flu tag) to the amino terminus of ARP-1/COUP-TFII abolished its ability to bind to DNA without affecting its repressor activity. By using a series of Flu-tagged mutants, the domains required for transrepressor activity of the protein were mapped. They include the DNA binding domain and the segment spanning residues 193 to 399. Transcriptional activity induced by liver-enriched transactivators such as hepatocyte nuclear factor 3 (HNF-3), C/EBP, or HNF-4 was repressed by ARP-1/COUP-TFII independent of the presence of its cognate binding site, while basal transcription or transcriptional activity induced by ATF or Sp1 was not perturbed by the protein. In

  7. Functional domains of the human orphan receptor ARP-1/COUP-TFII involved in active repression and transrepression.

    PubMed Central

    Achatz, G; Hölzl, B; Speckmayer, R; Hauser, C; Sandhofer, F; Paulweber, B

    1997-01-01

    The orphan receptor ARP-1/COUP-TFII, a member of the chicken ovalbumin upstream promoter transcription factor (COUP-TF) subfamily of nuclear receptors, strongly represses transcriptional activity of numerous genes, including several apolipoprotein-encoding genes. Recently it has been demonstrated that the mechanism by which COUP-TFs reduce transcriptional activity involves active repression and transrepression. To map the domains of ARP-1/COUP-TFII required for repressor activity, a detailed deletion analysis of the protein was performed. Chimeric proteins in which various segments of the ARP-1/COUP-TFII carboxy terminus were fused to the GAL4 DNA binding domain were used to characterize its active repression domain. The smallest segment confering active repressor activity to a heterologous DNA binding domain was found to comprise residues 210 to 414. This domain encompasses the region of ARP-1/COUP-TFII corresponding to helices 3 to 12 in the recently published crystal structure of other members of the nuclear receptor superfamily. It includes the AF-2 AD core domain formed by helix 12 but not the hinge region, which is essential for interaction with a corepressor in the case of the thyroid hormone and retinoic acid receptor. Attachment of the nuclear localization signal from the simian virus 40 large T antigen (Flu tag) to the amino terminus of ARP-1/COUP-TFII abolished its ability to bind to DNA without affecting its repressor activity. By using a series of Flu-tagged mutants, the domains required for transrepressor activity of the protein were mapped. They include the DNA binding domain and the segment spanning residues 193 to 399. Transcriptional activity induced by liver-enriched transactivators such as hepatocyte nuclear factor 3 (HNF-3), C/EBP, or HNF-4 was repressed by ARP-1/COUP-TFII independent of the presence of its cognate binding site, while basal transcription or transcriptional activity induced by ATF or Sp1 was not perturbed by the protein. In

  8. Beam emittance from ARPES for photoinjectors

    NASA Astrophysics Data System (ADS)

    Harkay, Katherine; Spentzouris, Linda; Nemeth, Karoly; Droubay, Timothy; Chambers, Scott; Joly, Alan; Hess, Wayne

    2014-03-01

    A commonly-used beam emittance measurement for photoinjector sources involves accelerating a low-charge beam to a few megavolts in an electron gun, then using a pepper-pot emittance diagnostic to image the transverse charge distribution. The emission distribution at the cathode surface could in principle be deduced through simulations, but cannot be measured directly with this method. In the quest to develop ultra-bright photoinjectors, it would be advantageous to be able to measure the emission distribution directly, and use this as a screening process to characterize different photocathode candidates. Angle-resolved photoemission sepctroscopy (ARPES), used widely in surface science, has been proposed [H. Padmore (private communication)] as a method to measure the photocathode intrinsic emittance. A promising novel photocathode, a thin layer of MgO on Ag was recently fabricated and ARPES measurements were carried out [T.C. Droubay et al., PRL (in press)]. The analysis of these data and resulting emittance will be presented. Implications for its use in simulations and design of future photoinjectors will also be presented. This work was supported by the U.S. DOE Office of Science (DE-AC02-06CH11357) and the National Science Foundation (No. PHY-0969989). The measurements were carried out at the EMSL user facility at PNNL.

  9. Actin Filament Elongation in Arp2/3-derived Networks is Controlled by Three Distinct Mechanisms

    PubMed Central

    Michelot, Alphée; Grassart, Alexandre; Okreglak, Voytek; Costanzo, Michael; Boone, Charles; Drubin, David G.

    2012-01-01

    Summary Spatial and temporal control of actin filament barbed end elongation is crucial for force generation by actin networks. In this study, genetics, cell biology, and biochemistry were used to reveal three complementary mechanisms that regulate actin filament barbed end elongation in Arp2/3-derived networks. Aip1 inhibits elongation of aged ADP-actin filaments decorated with cofilin, and together with capping protein (CP), maintains a high level of assembly-competent actin species. We identified Abp1 and Aim3 as two additional proteins that work together to inhibit barbed end elongation. Abp1/Aim3 collaborates with CP to control elongation of newly assembled ATP-actin filaments to organize filament polarity within actin networks. Thus, three distinct mechanisms control filament elongation in different regions of Arp2/3 networks, maintaining pools of assembly-competent actin species while ensuring proper filament polarity and facilitating force production. PMID:23333351

  10. Actin filament elongation in Arp2/3-derived networks is controlled by three distinct mechanisms.

    PubMed

    Michelot, Alphée; Grassart, Alexandre; Okreglak, Voytek; Costanzo, Michael; Boone, Charles; Drubin, David G

    2013-01-28

    Spatial and temporal control of actin filament barbed end elongation is crucial for force generation by actin networks. In this study, genetics, cell biology, and biochemistry were used to reveal three complementary mechanisms that regulate actin filament barbed end elongation in Arp2/3-derived networks. Aip1 inhibits elongation of aged ADP-actin filaments decorated with cofilin and, together with capping protein (CP), maintains a high level of assembly-competent actin species. We identified Abp1 and Aim3 as two additional proteins that work together to inhibit barbed end elongation. Abp1/Aim3 collaborates with CP to control elongation of newly assembled ATP-actin filaments to organize filament polarity within actin networks. Thus, three distinct mechanisms control filament elongation in different regions of Arp2/3 networks, maintaining pools of assembly-competent actin species while ensuring proper filament polarity and facilitating force production. PMID:23333351

  11. Difference gel electrophoresis identifies differentially expressed proteins in endoscopically collected pancreatic fluid.

    PubMed

    Paulo, Joao A; Lee, Linda S; Banks, Peter A; Steen, Hanno; Conwell, Darwin L

    2011-08-01

    Alterations in the pancreatic fluid proteome of individuals with chronic pancreatitis (CP) may offer insights into the development and progression of the disease. The endoscopic pancreatic function test (ePFT) can safely collect large volumes of pancreatic fluid that are potentially amenable to proteomic analyses using difference gel electrophoresis (DIGE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Pancreatic fluid was collected endoscopically using the ePFT method following secretin stimulation from three individuals with severe CP and three chronic abdominal pain (CAP) controls. The fluid was processed to minimize protein degradation and the protein profiles of each cohort, as determined by DIGE and LC-MS/MS, were compared. This DIGE-LC-MS/MS analysis reveals proteins that are differentially expressed in CP compared with CAP controls. Proteins with higher abundance in pancreatic fluid from CP individuals include: actin, desmoplankin, α-1-antitrypsin, SNC73, and serotransferrin. Those of relatively lower abundance include carboxypeptidase B, lipase, α-1-antichymotrypsin, α-2-macroglobulin, actin-related protein (Arp2/3) subunit 4, glyceraldehyde-3-phosphate dehydrogenase, and protein disulfide isomerase. Endoscopic collection (ePFT) in tandem with DIGE-LC-MS/MS is a suitable approach for pancreatic fluid proteome analysis; however, further optimization of our protocol, as outlined herein, may improve proteome coverage in future analyses. PMID:21792986

  12. The unbearable opaqueness of Arp220

    NASA Astrophysics Data System (ADS)

    Martín, S.; Aalto, S.; Sakamoto, K.; González-Alfonso, E.; Muller, S.; Henkel, C.; García-Burillo, S.; Aladro, R.; Costagliola, F.; Harada, N.; Krips, M.; Martín-Pintado, J.; Mühle, S.; van der Werf, P.; Viti, S.

    2016-05-01

    Context. The origin of the enormous luminosities of the two opaque nuclei of Arp 220, the prototypical ultra-luminous infrared galaxy, remains a mystery because we lack observational tools to explore the innermost regions around the nuclei. Aims: We explore the potential of imaging vibrationally excited molecular emission at high angular resolution to better understand the morphology and physical structure of the dense gas in Arp 220 and to gain insight into the nature of the nuclear powering sources. Methods: The Atacama Large Millimeter/submillimeter Array (ALMA) provided simultaneous observations of HCN, HCO+, and vibrationally excited HCN v2 = 1f emission. Their J = 4-3 and 3-2 transitions were observed at a matching resolution of ~0.5'', which allows us to isolate the emission from the two nuclei. Results: The HCN and HCO+ lines within the ground-vibrational state poorly describe the central ~100 pc region around the nuclei because there are strong effects of cool absorbing gas in the foreground and severe line blending that is due to the prolific molecular emission of Arp 220. Vibrationally excited emission of HCN is detected in both nuclei with a very high ratio relative to the total LFIR, higher than in any other observed galaxy and well above what is observed in Galactic hot cores. HCN v2 = 1f is observed to be marginally resolved in ~60 × 50 pc regions inside the dusty ~100 pc sized nuclear cores. Its emission is centered on our derived individual nuclear velocities based on HCO+ emission (VWN = 5342 ± 4 and VEN = 5454 ± 8 km s-1, for the western and eastern nucleus, respectively). With virial masses within r ~ 25-30 pc based on the HCN v2 = 1f line widths, we estimate gas surface densities (gas fraction fg = 0.1) of 3 ± 0.3 × 104 M⊙ pc-2 (WN) and 1.1 ± 0.1 × 104 M⊙ pc-2 (EN). The 4-3/3-2 flux density ratio could be consistent with optically thick emission, which would further constrain the size of the emitting region to >15 pc (EN) and >22 pc

  13. Application of SAE ARP4754A to Flight Critical Systems

    NASA Technical Reports Server (NTRS)

    Peterson, Eric M.

    2015-01-01

    This report documents applications of ARP4754A to the development of modern computer-based (i.e., digital electronics, software and network-based) aircraft systems. This study is to offer insight and provide educational value relative to the guidelines in ARP4754A and provide an assessment of the current state-of-the- practice within industry and regulatory bodies relative to development assurance for complex and safety-critical computer-based aircraft systems.

  14. DS-ARP: A New Detection Scheme for ARP Spoofing Attacks Based on Routing Trace for Ubiquitous Environments

    PubMed Central

    Song, Min Su; Lee, Jae Dong; Jeong, Hwa-Young; Park, Jong Hyuk

    2014-01-01

    Despite the convenience, ubiquitous computing suffers from many threats and security risks. Security considerations in the ubiquitous network are required to create enriched and more secure ubiquitous environments. The address resolution protocol (ARP) is a protocol used to identify the IP address and the physical address of the associated network card. ARP is designed to work without problems in general environments. However, since it does not include security measures against malicious attacks, in its design, an attacker can impersonate another host using ARP spoofing or access important information. In this paper, we propose a new detection scheme for ARP spoofing attacks using a routing trace, which can be used to protect the internal network. Tracing routing can find the change of network movement path. The proposed scheme provides high constancy and compatibility because it does not alter the ARP protocol. In addition, it is simple and stable, as it does not use a complex algorithm or impose extra load on the computer system. PMID:25243205

  15. Importance of Matrix Elements in the ARPES Spectra of BISCO

    SciTech Connect

    Bansil, A.; Lindroos, M.

    1999-12-13

    We have carried out extensive first-principles angle-resolved photointensity (ARPES) simulations in Bi2212 wherein the photoemission process is modeled realistically by taking into account the full crystal wave functions of the initial and final states in the presence of the surface. The spectral weight of the ARPES feature associated with the CuO{sub 2} plane bands is found to undergo large and systematic variations with k{sub (parallel} {sub sign)} as well as the energy and polarization of the incident photons. These theoretical predictions are in good accord with the corresponding measurements, indicating that the remarkable observed changes in the spectral weights in Bi2212 are essentially a matrix element effect and that the importance of matrix elements should be kept in mind in analyzing the ARPES spectra in the high T{sub c} 's. (c) 1999 The American Physical Society.

  16. Importance of Matrix Elements in the ARPES Spectra of BISCO

    NASA Astrophysics Data System (ADS)

    Bansil, A.; Lindroos, M.

    1999-12-01

    We have carried out extensive first-principles angle-resolved photointensity (ARPES) simulations in Bi2212 wherein the photoemission process is modeled realistically by taking into account the full crystal wave functions of the initial and final states in the presence of the surface. The spectral weight of the ARPES feature associated with the CuO2 plane bands is found to undergo large and systematic variations with k∥ as well as the energy and polarization of the incident photons. These theoretical predictions are in good accord with the corresponding measurements, indicating that the remarkable observed changes in the spectral weights in Bi2212 are essentially a matrix element effect and that the importance of matrix elements should be kept in mind in analyzing the ARPES spectra in the high Tc's.

  17. Research on implementation of proxy Arp in IP DSLAM

    NASA Astrophysics Data System (ADS)

    Cheng, Chuanqing; Wang, Li; Huang, Qiugen

    2005-02-01

    While the ethernet is applied more and more in public network environment and xdsl service become the most common access mode ,IP kenel DSLAM undertakes some functions such as service distribution and convergence ,security management and customer management.Facing the contradiction of the need of port isolation and the shortage of ip address,VLAN aggregation technology is applied in DSLAM.How to implement the communicatio between the two vlan but share the same ip subnet,proxy arp does this. This paper introduces how to implement proxy arp in the DSLAM. TCP/IP communication detail procedure betweent two host ,the relation of VLAN and network segment are discussed. The proxy arp model and its implementation in IP DSLAM is also expatiated in this paper and a conformance tesing is given.

  18. The remarkable infrared galaxy Arp 220 = IC 4553

    NASA Technical Reports Server (NTRS)

    Soifer, B. T.; Neugebauer, G.; Helou, G.; Lonsdale, C. J.; Hacking, P.; Rice, W.; Houck, J. R.; Low, F. J.; Rowan-Robinson, M.

    1984-01-01

    IRAS observations of the peculiar galaxy Arp 220 = IC 4553 show that it is extremely luminous in the far-infrared, with a total luminosity of 2 x 10 to the 12th solar luminosities. The infrared-to-blue luminosity ratio of this galaxy is about 80, which is the largest value of the ratio for galaxies in the UGC catalog, and places it in the range of the 'unidentified' infrared sources recently reported by Houck et al. in the IRAS all-sky survey. Other observations of Arp 220, combined with the luminosity in the infrared, allow either a Seyfert-like or starburst origin for this luminosity.

  19. Importance of Matrix Elements in the ARPES Spectra of BISCO

    NASA Astrophysics Data System (ADS)

    Bansil, A.; Lindroos, M.

    2000-03-01

    We have carried out extensive first-principles angle-resolved photointensity (ARPES) simulations in Bi2212 wherein the photoemission process is modelled realistically by taking into account the full crystal wavefunctions of the initial and final states in the presence of the surface.(A. Bansil and M. Lindroos, Phys. Rev. Letters (Dec 13, 1999)) The spectral weight of the ARPES feature associated with the CuO2 plane bands is found to undergo large and systematic variations with k_allel as well as the energy and polarization of the incident photons. These theoretical predictions are in good accord with the corresponding measurements, indicating that the remarkable observed changes in the spectral weights in Bi2212 are essentially a matrix element effect and that the importance of matrix elements should be kept in mind in analyzing the ARPES spectra in the high-Tc's. Another notable implication of this work is that the integral (over energy) of the ARPES intensity does not yield the momentum density of the electron gas. We will also discuss some of our simulations aimed at gaining insight into the connectivity of the Fermi surface in Bi2212 around the M-point, the effects of modulations, and related issues. Work supported in part by the U.S.D.O.E.

  20. The anisotropic properties of high temperature superconductors - an ARPES study

    NASA Astrophysics Data System (ADS)

    Kaminski, Adam; Fretwell, Helen; Mesot, Joel; Rozenkrantz, Stephan; Djendjinovic, Marin; Campuzano, Juan; Randeria, Mohit; Norman, Michael; Sato, Takafumi; Takahashi, Takashi; Kadowaki, Kazuo; Hinks, David; Raffy, Helen

    2001-03-01

    It is now well established that cuprates are d-wave superconductors. Natural question arises concerning the symmetry of other electronic properties in these materials and their relation to anisotropic order parameter. We present our recent ARPES measurements of these properties performed on a the same sample of single cristal BISCO 2212.

  1. Extreme-ultraviolet ultrafast ARPES at high repetition rates

    NASA Astrophysics Data System (ADS)

    Buss, Jan; Wang, He; Xu, Yiming; Stoll, Sebastian; Zeng, Lingkun; Ulonska, Stefan; Denlinger, Jonathan; Hussain, Zahid; Jozwiak, Chris; Lanzara, Alessandra; Kaindl, Robert

    Time- and angle-resolved photoemission spectroscopy (trARPES) represents a powerful approach to resolve the electronic structure and quasiparticle dynamics in complex materials, yet is often limited in either momentum space (incident photon energy), probe sensitivity (pulse repetition rate), or energy resolution. We demonstrate a novel table-top trARPES setup that combines a bright 50-kHz source of narrowband, extreme ultraviolet (XUV) pulses at 22.3 eV with UHV photoemission instrumentation to sensitively access dynamics for a large momentum space. The output of a high-power Ti:sapphire amplifier is split to provide the XUV probe and intense photoexcitation (up to mJ/cm2) . A vacuum beamline delivers spectral and flux characterization, differential pumping, as well as XUV beam steering and toroidal refocusing onto the sample with high incident flux of 3x1011 ph/s. Photoemission studies are carried out in a customized UHV chamber equipped with a hemispherical analyzer (R4000), six-axis sample cryostat, and side chambers for sample loading, storage and preparation. An ARPES energy resolution down to 70 meV with the direct XUV output is demonstrated. We will discuss initial applications of this setup including Fermi surface mapping and trARPES of complex materials.

  2. Nutraceutical with Resveratrol and Omega-3 Fatty Acids Induces Autophagy in ARPE-19 Cells

    PubMed Central

    Koskela, Ali; Reinisalo, Mika; Petrovski, Goran; Sinha, Debasish; Olmiere, Céline; Karjalainen, Reijo; Kaarniranta, Kai

    2016-01-01

    Impaired autophagic and proteasomal cleansing have been documented in aged retinal pigment epithelial (RPE) cells and age-related macular degeneration (AMD). Omega-3 fatty acids and resveratrol have many positive homeostatic effects in RPE cells. In this work, ARPE-19 cells were treated with 288 ng of Resvega, containing 30 mg of trans resveratrol and 665 mg of omega-3 fatty acids, among other nutrients, with proteasome inhibitor MG-132 or autophagy inhibitor bafilomycin A1 up to 48 h. Autophagy markers p62/SQSTM1 (p62) and LC3 (microtubule-associated protein 1A/1B-light chain 3) were analyzed by Western blotting. Fluorescence microscopy with mCherry-GFP-LC3 plasmid was applied to study the autophagy flux, and cytoprotective effects were investigated with colorimetric MTT and LDH assays. Resvega induced autophagy by showing increased autolysosome formation and autophagy flux, and the change in the p62 and LC3 protein levels further confirmed the fluorescent microscopy results. Moreover, Resvega provided a clear cytoprotection under proteasome inhibition. These findings highlight the potential of the nutraceuticals containing resveratrol, omega-3 fatty acids and other nutrients in the prevention of ARPE-19 cell damage. PMID:27187449

  3. Nutraceutical with Resveratrol and Omega-3 Fatty Acids Induces Autophagy in ARPE-19 Cells.

    PubMed

    Koskela, Ali; Reinisalo, Mika; Petrovski, Goran; Sinha, Debasish; Olmiere, Céline; Karjalainen, Reijo; Kaarniranta, Kai

    2016-01-01

    Impaired autophagic and proteasomal cleansing have been documented in aged retinal pigment epithelial (RPE) cells and age-related macular degeneration (AMD). Omega-3 fatty acids and resveratrol have many positive homeostatic effects in RPE cells. In this work, ARPE-19 cells were treated with 288 ng of Resvega, containing 30 mg of trans resveratrol and 665 mg of omega-3 fatty acids, among other nutrients, with proteasome inhibitor MG-132 or autophagy inhibitor bafilomycin A1 up to 48 h. Autophagy markers p62/SQSTM1 (p62) and LC3 (microtubule-associated protein 1A/1B-light chain 3) were analyzed by Western blotting. Fluorescence microscopy with mCherry-GFP-LC3 plasmid was applied to study the autophagy flux, and cytoprotective effects were investigated with colorimetric MTT and LDH assays. Resvega induced autophagy by showing increased autolysosome formation and autophagy flux, and the change in the p62 and LC3 protein levels further confirmed the fluorescent microscopy results. Moreover, Resvega provided a clear cytoprotection under proteasome inhibition. These findings highlight the potential of the nutraceuticals containing resveratrol, omega-3 fatty acids and other nutrients in the prevention of ARPE-19 cell damage. PMID:27187449

  4. Evolution of the eukaryotic ARP2/3 activators of the WASP family: WASP, WAVE, WASH, and WHAMM, and the proposed new family members WAWH and WAML

    PubMed Central

    2012-01-01

    Background WASP family proteins stimulate the actin-nucleating activity of the ARP2/3 complex. They include members of the well-known WASP and WAVE/Scar proteins, and the recently identified WASH and WHAMM proteins. WASP family proteins contain family specific N-terminal domains followed by proline-rich regions and C-terminal VCA domains that harbour the ARP2/3-activating regions. Results To reveal the evolution of ARP2/3 activation by WASP family proteins we performed a "holistic" analysis by manually assembling and annotating all homologs in most of the eukaryotic genomes available. We have identified two new families: the WAML proteins (WASP and MIM like), which combine the membrane-deforming and actin bundling functions of the IMD domains with the ARP2/3-activating VCA regions, and the WAWH protein (WASP without WH1 domain) that have been identified in amoebae, Apusozoa, and the anole lizard. Surprisingly, with one exception we did not identify any alternative splice forms for WASP family proteins, which is in strong contrast to other actin-binding proteins like Ena/VASP, MIM, or NHS proteins that share domains with WASP proteins. Conclusions Our analysis showed that the last common ancestor of the eukaryotes must have contained a homolog of WASP, WAVE, and WASH. Specific families have subsequently been lost in many taxa like the WASPs in plants, algae, Stramenopiles, and Euglenozoa, and the WASH proteins in fungi. The WHAMM proteins are metazoa specific and have most probably been invented by the Eumetazoa. The diversity of WASP family proteins has strongly been increased by many species- and taxon-specific gene duplications and multimerisations. All data is freely accessible via http://www.cymobase.org. PMID:22316129

  5. Las17p-Vrp1p but not Las17p-Arp2/3 interaction is important for actin patch polarization in yeast.

    PubMed

    Rajmohan, Rajamuthiah; Wong, Ming Hwa; Meng, Lei; Munn, Alan L; Thanabalu, Thirumaran

    2009-05-01

    The actin cytoskeleton plays a central role in many important cellular processes such as cell polarization, cell division and endocytosis. The dynamic changes to the actin cytoskeleton that accompany these processes are regulated by actin-associated proteins Wiskott-Aldrich Syndrome Protein (WASP) (known as Las17p in yeast) and WASP-Interacting Protein (WIP) (known as Vrp1p in yeast). Both yeast and human WASP bind to and stimulate the Arp2/3 complex which in turn nucleates assembly of actin monomers into filaments at polarized sites at the cortex. WASP-WIP interaction in yeast and humans are important for Arp2/3 complex stimulation in vitro. It has been proposed that these interactions are also important for polarized actin assembly in vivo. However, the redundancy of actin-associated proteins has made it difficult to test this hypothesis. We have identified two point mutations (L80T and H94L) in yeast WASP that in combination abolish WASP-WIP interaction in yeast. We also identify an N-terminal fragment of Las17p (N-Las17p1-368) able to interact with Vrp1p but not Arp2/3. Using these mutant and truncated forms of yeast WASP we provide novel evidence that WASP interaction with WIP is more important than interaction with Arp2/3 for polarized actin assembly and endocytosis in yeast. PMID:19272406

  6. MOX Cross-Section Libraries for ORIGEN-ARP

    SciTech Connect

    Gauld, I.C.

    2003-07-01

    The use of mixed-oxide (MOX) fuel in commercial nuclear power reactors operated in Europe has expanded rapidly over the past decade. The predicted characteristics of MOX fuel such as the nuclide inventories, thermal power from decay heat, and radiation sources are required for design and safety evaluations, and can provide valuable information for non-destructive safeguards verification activities. This report describes the development of computational methods and cross-section libraries suitable for the analysis of irradiated MOX fuel with the widely-used and recognized ORIGEN-ARP isotope generation and depletion code of the SCALE (Standardized Computer Analyses for Licensing Evaluation) code system. The MOX libraries are designed to be used with the Automatic Rapid Processing (ARP) module of SCALE that interpolates appropriate values of the cross sections from a database of parameterized cross-section libraries to create a problem-dependent library for the burnup analysis. The methods in ORIGEN-ARP, originally designed for uranium-based fuels only, have been significantly upgraded to handle the larger number of interpolation parameters associated with MOX fuels. The new methods have been incorporated in a new version of the ARP code that can generate libraries for low-enriched uranium (LEU) and MOX fuel types. The MOX data libraries and interpolation algorithms in ORIGEN-ARP have been verified using a database of declared isotopic concentrations for 1042 European MOX fuel assemblies. The methods and data are validated using a numerical MOX fuel benchmark established by the Organization for Economic Cooperation and Development (OECD) Working Group on burnup credit and nuclide assay measurements for irradiated MOX fuel performed as part of the Belgonucleaire ARIANE International Program.

  7. WISp39 binds phosphorylated Coronin 1B to regulate Arp2/3 localization and Cofilin-dependent motility.

    PubMed

    Howell, Michael; Brickner, Howard; Delorme-Walker, Violaine D; Choi, Justin; Saffin, Jean-Michel; Miller, Daniel; Panopoulos, Andreas; DerMardirossian, Céline; Fotedar, Arun; Margolis, Robert L; Fotedar, Rati

    2015-03-30

    We previously identified Waf1 Cip1 stabilizing protein 39 (WISp39) as a binding partner for heat shock protein 90 (Hsp90). We now report that WISp39 has an essential function in the control of directed cell migration, which requires WISp39 interaction with Hsp90. WISp39 knockdown (KD) resulted in the loss of directional motility of mammalian cells and profound changes in cell morphology, including the loss of a single leading edge. WISp39 binds Coronin 1B, known to regulate the Arp2/3 complex and Cofilin at the leading edge. WISp39 preferentially interacts with phosphorylated Coronin 1B, allowing it to complex with Slingshot phosphatase (SSH) to dephosphorylate and activate Cofilin. WISp39 also regulates Arp2/3 complex localization at the leading edge. WISp39 KD-induced morphological changes could be rescued by overexpression of Coronin 1B together with a constitutively active Cofilin mutant. We conclude that WISp39 associates with Hsp90, Coronin 1B, and SSH to regulate Cofilin activation and Arp2/3 complex localization at the leading edge. PMID:25800056

  8. Expression of ADAMTS metalloproteinases in the retinal pigment epithelium derived cell line ARPE-19: transcriptional regulation by TNFalpha.

    PubMed

    Bevitt, Debra J; Mohamed, Jeseem; Catterall, Jon B; Li, Zheng; Arris, Christine E; Hiscott, Paul; Sheridan, Carl; Langton, Kevin P; Barker, Michael D; Clarke, Michael P; McKie, Norman

    2003-04-15

    ADAMTS (A Disintegrin-like And Metalloprotease domain with ThromboSpondin type I motifs) are multidomain proteins with demonstrated metalloproteinase functionality and have potential roles in embryonic development, angiogenesis and cartilage degradation. We present here investigations of ADAMTS expression in an ocular cell type, ARPE-19, with a view to implicating them in retinal matrix turnover. Expression analysis was undertaken using a combination of reverse transcription polymerase chain reaction (RT-PCR) and Northern blotting experiments, which together detected the expression of mRNAs for several ADAMTS proteins, all of which have active site motifs characteristic of matrix metalloproteases (MMPs). These included ADAMTS1, ADAMTS2, ADAMTS3, ADAMTS5, ADAMTS6, ADAMTS7 and ADAMTS9. The expression of mRNA isoforms for ADAMTS7 and ADAMTS9 were also detected. Following stimulation with TNFalpha, ADAMTS1, ADAMTS6 and both ADAMTS9 transcripts expressed in ARPE-19 cells showed a potent upregulation. The expression of ADAMTS genes in ARPE-19 cells and the transcriptional stimulation of some family members by TNFalpha may implicate them in inflammatory eye disease and the compromise of retinal matrix structure, which is evident in age-related macular degeneration (ARMD) and other retinal pathologies. PMID:12697333

  9. Rickettsia parkeri invasion of diverse host cells involves an Arp2/3 complex, WAVE complex and Rho-family GTPase-dependent pathway.

    PubMed

    Reed, Shawna C O; Serio, Alisa W; Welch, Matthew D

    2012-04-01

    Rickettsiae are obligate intracellular pathogens that are transmitted to humans by arthropod vectors and cause diseases such as spotted fever and typhus. Although rickettsiae require the host cell actin cytoskeleton for invasion, the cytoskeletal proteins that mediate this process have not been completely described. To identify the host factors important during cell invasion by Rickettsia parkeri, a member of the spotted fever group (SFG), we performed an RNAi screen targeting 105 proteins in Drosophila melanogaster S2R+ cells. The screen identified 21 core proteins important for invasion, including the GTPases Rac1 and Rac2, the WAVE nucleation-promoting factor complex and the Arp2/3 complex. In mammalian cells, including endothelial cells, the natural targets of R. parkeri, the Arp2/3 complex was also crucial for invasion, while requirements for WAVE2 as well as Rho GTPases depended on the particular cell type. We propose that R. parkeri invades S2R+ arthropod cells through a primary pathway leading to actin nucleation, whereas invasion of mammalian endothelial cells occurs via redundant pathways that converge on the host Arp2/3 complex. Our results reveal a key role for the WAVE and Arp2/3 complexes, as well as a higher degree of variation than previously appreciated in actin nucleation pathways activated during Rickettsia invasion. PMID:22188208

  10. Prediction of antibiotic resistance proteins from sequence-derived properties irrespective of sequence similarity.

    PubMed

    Zhang, H L; Lin, H H; Tao, L; Ma, X H; Dai, J L; Jia, J; Cao, Z W

    2008-09-01

    Increasing antibiotic resistance has become a worldwide challenge to the clinical treatment of infectious diseases. The identification of antibiotic resistance proteins (ARPs) would be helpful in the discovery of new therapeutic targets and the design of novel drugs to control the potential spread of antibiotic resistance. In this work, a support vector machine (SVM)-based ARP prediction system was developed using 1308 ARPs and 15587 non-ARPs. Its performance was evaluated using 313 ARPs and 7156 non-ARPs. The computed prediction accuracy was 88.5% for ARPs and 99.2% for non-ARPs. A potential application of this method is the identification of ARPs non-homologous to proteins of known function. Further genome screening found that ca. 3.5% and 3.2% of proteins in Escherichia coli and Staphylococcus aureus, respectively, are potential ARPs. These results suggest the usefulness of SVMs for facilitating the identification of ARPs. The software can be accessed at SARPI (Server for Antibiotic Resistance Protein Identification). PMID:18583101

  11. Diffusion, capture and recycling of SCAR/WAVE and Arp2/3 complexes observed in cells by single-molecule imaging.

    PubMed

    Millius, Arthur; Watanabe, Naoki; Weiner, Orion D

    2012-03-01

    The SCAR/WAVE complex drives lamellipodium formation by enhancing actin nucleation by the Arp2/3 complex. Phosphoinositides and Rac activate the SCAR/WAVE complex, but how SCAR/WAVE and Arp2/3 complexes converge at sites of nucleation is unknown. We analyzed the single-molecule dynamics of WAVE2 and p40 (subunits of the SCAR/WAVE and Arp2/3 complexes, respectively) in XTC cells. We observed lateral diffusion of both proteins and captured the transition of p40 from diffusion to network incorporation. These results suggest that a diffusive 2D search facilitates binding of the Arp2/3 complex to actin filaments necessary for nucleation. After nucleation, the Arp2/3 complex integrates into the actin network and undergoes retrograde flow, which results in its broad distribution throughout the lamellipodium. By contrast, the SCAR/WAVE complex is more restricted to the cell periphery. However, with single-molecule imaging, we also observed WAVE2 molecules undergoing retrograde motion. WAVE2 and p40 have nearly identical speeds, lifetimes and sites of network incorporation. Inhibition of actin retrograde flow does not prevent WAVE2 association and disassociation with the membrane but does inhibit WAVE2 removal from the actin cortex. Our results suggest that membrane binding and diffusion expedites the recruitment of nucleation factors to a nucleation site independent of actin assembly, but after network incorporation, ongoing actin polymerization facilitates recycling of SCAR/WAVE and Arp2/3 complexes. PMID:22349699

  12. Apolipoprotein B100 secretion by cultured ARPE-19 cells is modulated by alteration of cholesterol levels.

    PubMed

    Wu, Tinghuai; Fujihara, Masashi; Tian, Jane; Jovanovic, Miroslava; Grayson, Celene; Cano, Marisol; Gehlbach, Peter; Margaron, Philippe; Handa, James T

    2010-09-01

    Cholesteryl ester rich apolipoprotein B100 (apoB100) lipoproteins accumulate in Bruch's membrane before the development of age-related macular degeneration. It is not known if these lipoproteins come from the circulation or local ocular tissue. Emerging, but incomplete evidence suggests that the retinal pigmented epithelium (RPE) can secrete lipoproteins. The purpose of this investigation was to determine (i) whether human RPE cells synthesize and secrete apoB100, and (ii) whether this secretion is driven by cellular cholesterol, and if so, (iii) whether statins inhibit this response. The established, human derived ARPE-19 cells challenged with 0-0.8 mM oleic acid accumulated cellular cholesterol, but not triglycerides. Oleic acid increased the amount of apoB100 protein recovered from the medium by both western blot analysis and (35) S-radiolabeled immunoprecipitation while negative stain electron microscopy showed lipoprotein-like particles. Of nine statins evaluated, lipophilic statins induced HMG-CoA reductase mRNA expression the most. The lipophilic Cerivastatin (5 μM) reduced cellular cholesterol by 39% and abrogated apoB100 secretion by 3-fold. In contrast, the hydrophilic statin Pravastatin had minimal effect on apoB100 secretion. These data suggest that ARPE-19 cells synthesize and secrete apoB100 lipoproteins, that this secretion is driven by cellular cholesterol, and that statins can inhibit apoB100 secretion by reducing cellular cholesterol. PMID:20598021

  13. Forgetting is regulated via Musashi-mediated translational control of the Arp2/3 complex.

    PubMed

    Hadziselimovic, Nils; Vukojevic, Vanja; Peter, Fabian; Milnik, Annette; Fastenrath, Matthias; Fenyves, Bank Gabor; Hieber, Petra; Demougin, Philippe; Vogler, Christian; de Quervain, Dominique J-F; Papassotiropoulos, Andreas; Stetak, Attila

    2014-03-13

    A plastic nervous system requires the ability not only to acquire and store but also to forget. Here, we report that musashi (msi-1) is necessary for time-dependent memory loss in C. elegans. Tissue-specific rescue demonstrates that MSI-1 function is necessary in the AVA interneuron. Using RNA-binding protein immunoprecipitation (IP), we found that MSI-1 binds to mRNAs of three subunits of the Arp2/3 actin branching regulator complex in vivo and downregulates ARX-1, ARX-2, and ARX-3 translation upon associative learning. The role of msi-1 in forgetting is also reflected by the persistence of learning-induced GLR-1 synaptic size increase in msi-1 mutants. We demonstrate that memory length is regulated cooperatively through the activation of adducin (add-1) and by the inhibitory effect of msi-1. Thus, a GLR-1/MSI-1/Arp2/3 pathway induces forgetting and represents a novel mechanism of memory decay by linking translational control to the structure of the actin cytoskeleton in neurons. PMID:24630719

  14. The Legionella Kinase LegK2 Targets the ARP2/3 Complex To Inhibit Actin Nucleation on Phagosomes and Allow Bacterial Evasion of the Late Endocytic Pathway

    PubMed Central

    Michard, Céline; Sperandio, Daniel; Baïlo, Nathalie; Pizarro-Cerdá, Javier; LeClaire, Lawrence; Chadeau-Argaud, Elise; Pombo-Grégoire, Isabel; Hervet, Eva; Vianney, Anne; Gilbert, Christophe; Faure, Mathias; Cossart, Pascale

    2015-01-01

    ABSTRACT Legionella pneumophila, the etiological agent of legionellosis, replicates within phagocytic cells. Crucial to biogenesis of the replicative vacuole is the Dot/Icm type 4 secretion system, which translocates a large number of effectors into the host cell cytosol. Among them is LegK2, a protein kinase that plays a key role in Legionella infection. Here, we identified the actin nucleator ARP2/3 complex as a target of LegK2. LegK2 phosphorylates the ARPC1B and ARP3 subunits of the ARP2/3 complex. LegK2-dependent ARP2/3 phosphorylation triggers global actin cytoskeleton remodeling in cells, and it impairs actin tail formation by Listeria monocytogenes, a well-known ARP2/3-dependent process. During infection, LegK2 is addressed to the Legionella-containing vacuole surface and inhibits actin polymerization on the phagosome, as revealed by legK2 gene inactivation. Consequently, LegK2 prevents late endosome/lysosome association with the phagosome and finally contributes to remodeling of the bacterium-containing phagosome into a replicative niche. The inhibition of actin polymerization by LegK2 and its effect on endosome trafficking are ARP2/3 dependent since it can be phenocopied by a specific chemical inhibitor of the ARP2/3 complex. Thus, LegK2-ARP2/3 interplay highlights an original mechanism of bacterial virulence with an unexpected role in local actin remodeling that allows bacteria to control vesicle trafficking in order to escape host defenses. PMID:25944859

  15. Phase Stability and the Velocity Dependence of the ARP Force

    NASA Astrophysics Data System (ADS)

    Elgin, John; Arnold, Brian; Inaki, Taichi; Fang, Yifan; Metcalf, Harold

    2016-05-01

    Adiabatic Rapid Passage (ARP) has been shown to produce optical forces much stronger than the usual radiative force. Recent work has found that the ARP force is very sensitive to the phase of the optical field. Thus, the use of two free running, oppositely detuned lasers is not the ideal way to achieve an accurate measurement of the velocity dependence by mimicking the Doppler shift. We believe that phase locking the two lasers to a third, master laser will address these phase concerns, thereby allowing a proper measure of the velocity dependence. We have implemented this in our experiment and will present the results obtained from this change. We will also compare these results to those obtained using independent lasers and comment on the implications. Supported by ONR and GAANN - Dept. of Education.

  16. ARPES of K-doped iron selenide superconductor

    NASA Astrophysics Data System (ADS)

    Yokoya, Takayoshi; Sunagawa, Masanori; Terashima, Kensei; Hamada, Takahiro; Fujiwara, Hirokazu; Tanaka, Masashi; Takeya, Hiroyuki; Takano, Yoshihiko; Arita, Masashi; Shimada, Kenya; Namatame, Hirofumi; Taniguchi, Masaki; Suzuki, Katsuhiro; Usui, Hidetomo; Kuroki, Kazuhiko; Wakita, Takanori; Muraoka, Yuji

    2015-03-01

    In iron pnictide superconductors, the characteristic Fermi surface(FS) topology, namely nesting of hole-like FS at the zone center and electron-like FS at the zone corner, is considered to induce spin/orbital fluctuation leading to high-Tc superconductivity. In K-doped iron selenide superconductors, however, ARPES studies reported absence of hole-like FS at the zone center, which is different from that observed in iron pnictides. So far, proposed models for the superconductivity based on the FS topology appear to fail to explain available experimental results. In this talk, we present our recent ARPES studies on a K-doped iron selenide superconductor performed with careful tuning of experimental conditions, which show a hole-like FS around the zone center.

  17. Mid-infrared imaging of Markarian 231 and Arp 220

    SciTech Connect

    Keto, E.; Ball, R.; Arens, J.; Jernigan, G.; Meixner, M. Smithsonian Astrophysical Observatory, Cambridge, MA Lawrence Livermore National Laboratory, Livermore, CA Lawrence Livermore National Laboratory, Livermore, CA California University, Berkeley )

    1992-03-01

    High angular resolution observations of Arp 220 and Mrk 231 provide images of the nuclei and show that the source of the strong mid-IR emission is confined to regions less than about 0.5 arcsec or 400 pc in diameter in Mrk 231 and less than 1.5 arcsec x 0.9 arcsec or 320 x 530 pc in Arp 220. If much of the far-IR emission also derives from such a small region, the implied radiation densities are quite high, equivalent to one O star per cu pc. Although in normal galaxies the near-IR traces an older population of evolved, cool stars, such high radiation densities in the IR bright galaxies suggest the possibility that the spatial correlation observed between the near-IR, mid-IR, and radio may hold because emission in all three bands is associated with hot interstellar gas and dust. 23 refs.

  18. WFPC2 Observations of the Sagittarius Globular Cluster Arp 2

    NASA Astrophysics Data System (ADS)

    Dueñas, E. N.; Mighell, K. J.

    2002-12-01

    We present our preliminary analysis of archival Hubble Space Telescope WFPC2 observations in the F555W (V) and F814W (I) filters of the metal-poor globular cluster Arp 2 in the nearby Sagittarius dwarf spheroidal galaxy. The deep V vs. (V-I) color-magnitude diagram reaches 3.5 magnitudes below the main sequence turnoff with a signal-to-noise ratio of 10 or greater in both filters; it also features a well-defined subgiant branch as well as a few blue stragglers. The upper red giant branch is not analyzed due to photometric saturation. Most previous studies of Arp 2 analyzed the ground-based BV observations of Buonanno et al. (1995) or the ground-based VI observations of Sarajedini & Layden (1997). Buonanno et al. found that Arp 2 is a metal-poor, intermediate age cluster, while Layden & Sarajedini (2000) determined that it is coeval with other ancient Galactic globular clusters, e.g. 13.1 +/- 0.9 Gyr. We have analyzed our space-based observations with the Yonsei-Yale (Y2) isochrones of Yi et al. (2001) and present evidence that confirms the Layden & Sarajedini's ancient-age hypothesis for Arp 2. Dueñas was supported, in part, by awards to South Carolina State University from NASA/MU-SPIN (NCC 5-534) and NASA/OSS (NAG 5-10145), and the NOAO/KPNO REU Program, funded by the National Science Foundation. Mighell was supported by a grant from the National Aeronautics and Space Administration (NASA), S-67046-F, awarded by the Long-Term Space Astrophysics program of NASA's Office of Space Science.

  19. Fusion of the mouse IgG1 Fc domain to the VHH fragment (ARP1) enhances protection in a mouse model of rotavirus

    PubMed Central

    Günaydın, Gökçe; Yu, Shengze; Gräslund, Torbjörn; Hammarström, Lennart; Marcotte, Harold

    2016-01-01

    A variable fragment of a heavy chain antibody (VHH) directed against rotavirus, also referred to as anti-rotavirus protein 1 (ARP1), was shown to confer protection against rotavirus induced diarrhea in infant mouse model of rotavirus induced diarrhea. In this study, we have fused the mouse IgG1 Fc to ARP1 to improve the protective capacity of ARP1 by inducing an Fc-mediated effector function. We have shown that the Fc-ARP1 fusion protein confers significantly increased protection against rotavirus in a neonatal mouse model of rotavirus-induced diarrhea by reducing the prevalence, duration and severity of diarrhea and the viral load in the small intestines, suggesting that the Fc part of immunoglobulins may be engaged in Fc-mediated neutralization of rotavirus. Engineered conventional-like antibodies, by fusion of the Fc part of immunoglobulins to antigen-specific heavy-chain only VHH fragments, might be applied to novel antibody-based therapeutic approaches to enhance elimination of pathogens by activation of distinct effector signaling pathways. PMID:27439689

  20. Kv3.3 Channels Bind Hax-1 and Arp2/3 to Assemble a Stable Local Actin Network that Regulates Channel Gating.

    PubMed

    Zhang, Yalan; Zhang, Xiao-Feng; Fleming, Matthew R; Amiri, Anahita; El-Hassar, Lynda; Surguchev, Alexei A; Hyland, Callen; Jenkins, David P; Desai, Rooma; Brown, Maile R; Gazula, Valeswara-Rao; Waters, Michael F; Large, Charles H; Horvath, Tamas L; Navaratnam, Dhasakumar; Vaccarino, Flora M; Forscher, Paul; Kaczmarek, Leonard K

    2016-04-01

    Mutations in the Kv3.3 potassium channel (KCNC3) cause cerebellar neurodegeneration and impair auditory processing. The cytoplasmic C terminus of Kv3.3 contains a proline-rich domain conserved in proteins that activate actin nucleation through Arp2/3. We found that Kv3.3 recruits Arp2/3 to the plasma membrane, resulting in formation of a relatively stable cortical actin filament network resistant to cytochalasin D that inhibits fast barbed end actin assembly. These Kv3.3-associated actin structures are required to prevent very rapid N-type channel inactivation during short depolarizations of the plasma membrane. The effects of Kv3.3 on the actin cytoskeleton are mediated by the binding of the cytoplasmic C terminus of Kv3.3 to Hax-1, an anti-apoptotic protein that regulates actin nucleation through Arp2/3. A human Kv3.3 mutation within a conserved proline-rich domain produces channels that bind Hax-1 but are impaired in recruiting Arp2/3 to the plasma membrane, resulting in growth cones with deficient actin veils in stem cell-derived neurons. PMID:26997484

  1. Fusion of the mouse IgG1 Fc domain to the VHH fragment (ARP1) enhances protection in a mouse model of rotavirus.

    PubMed

    Günaydın, Gökçe; Yu, Shengze; Gräslund, Torbjörn; Hammarström, Lennart; Marcotte, Harold

    2016-01-01

    A variable fragment of a heavy chain antibody (VHH) directed against rotavirus, also referred to as anti-rotavirus protein 1 (ARP1), was shown to confer protection against rotavirus induced diarrhea in infant mouse model of rotavirus induced diarrhea. In this study, we have fused the mouse IgG1 Fc to ARP1 to improve the protective capacity of ARP1 by inducing an Fc-mediated effector function. We have shown that the Fc-ARP1 fusion protein confers significantly increased protection against rotavirus in a neonatal mouse model of rotavirus-induced diarrhea by reducing the prevalence, duration and severity of diarrhea and the viral load in the small intestines, suggesting that the Fc part of immunoglobulins may be engaged in Fc-mediated neutralization of rotavirus. Engineered conventional-like antibodies, by fusion of the Fc part of immunoglobulins to antigen-specific heavy-chain only VHH fragments, might be applied to novel antibody-based therapeutic approaches to enhance elimination of pathogens by activation of distinct effector signaling pathways. PMID:27439689

  2. Fermi Surface Topology and the ARPES Spectra of BISCO

    NASA Astrophysics Data System (ADS)

    Bansil, A.; Lindroos, M.

    2001-03-01

    The Fermi surface (FS) of BISCO has generated considerable recent controversy with attention focused on whether or not the FS is electron- or hole-like in the vicinity of the M(π,0) symmetry point. Given strong matrix element effects in BISCO[1], care is needed in ascertaining delicate FS features in terms of the the ARPES spectra. With this motivation, we have carried out extensive first-principles simulations of photointensity in the entire (k_x,k_y) plane for emission from the Fermi energy at a photon energy of 21.2 eV. The presence of electron or hole sheets in the underlying spectrum is simulated by varying the Fermi energy appropriately. The simulated ARPES spectra are analyzed using a variety of methods that have been invoked in the recent literature for the purpose of deducing FS topology in BISCO from the ARPES data. While different methods indeed help ameliorate matrix element effects to varying degrees, our study also reveals their limitations. The "renormalization" of the spectrum over a large energy window ( ~600 meV) tends to artificially introduce hole-like features, while the gradient of the total spectral weight has a tendancy to induce spurious electron-like features. These and related issues are discussed. Work supported in part by the U.S.D.O.E. [1] A. Bansil and M. Lindroos, Phys. Rev. Letters 83,5154(1999).

  3. A 21-cm Neutral Hydrogen Study of Arp 213

    NASA Astrophysics Data System (ADS)

    Wells, S. J.; Simpson, C. E.

    2002-12-01

    We present 21-cm VLA observations of the Sab galaxy Arp 213. An extended HI disk (approx. 2.3 RHolm) was detected, with a bifurcated or extra arm on the west featuring a large HI knot. Based on the kinematics, this knot does not appear to be a dwarf or small companion, but a local enhancement in the arm. Although no unusual kinematics appear in the region of the odd radial dust lanes that attracted Arp's attention to this galaxy, there is a very low level HI cloud just north of the galaxy at the same position angle. The total HI mass for the galaxy was measured to be 2.9 x 109 Msun. Arp 213 has a high rotational velocity (300 km s-1), and a flat rotation curve that rises in the outermost regions. The calculated dynamical mass for the system is quite high at 4.4 x 1011 Msun. The rotation curve and dynamic mass indicate the presence of a large dark matter halo. Further optical data is needed to confirm its mass. This work was supported by NSF grant AST-0097616 and the SARA Consortium REU program.

  4. Quercetin phospholipid complex significantly protects against oxidative injury in ARPE-19 cells associated with activation of Nrf2 pathway.

    PubMed

    Xu, Xin-Rong; Yu, Hai-Tao; Yang, Yan; Hang, Li; Yang, Xue-Wen; Ding, Shu-Hua

    2016-01-01

    Age-related macular degeneration (AMD) is a major cause of blindness worldwide. Oxidative stress plays a crucial role in the pathogenesis of dry AMD. Quercetin has potent anti-oxidative activities, but poor bioavailability limits its therapeutic application. Herein, we prepared the phospholipid complex of quercetin (quercetin-PC), characterized its structure by differential scanning calorimetry, infrared spectrum and x-ray diffraction. Quercetin-PC had equilibrium solubility of 38.36 and 1351.27μg/ml in water and chloroform, respectively, which was remarkably higher than those of quercetin alone. Then we established hydrogen peroxide (H2O2)-induced oxidative injury model in human ARPE-19 cells to examine the effects of quercetin-PC. Quercetin-PC, stronger than quercetin, promoted cell proliferation, and the proliferation rate was increased to be 78.89% when treated with Quercetin-PC at 400μM. Moreover, quercetin-PC effectively prevented ARPE-19 cells from apoptosis, and the apoptotic rate was reduced to be 3.1% when treated with Quercetin-PC at 200μM. In addition, quercetin-PC at 200μM significantly increased the activities of SOD, CAT and GSH-PX, and reduced the levels of reactive oxygen species and MDA in H2O2-treated ARPE-19 cells, but quercetin at 200μM failed to do so. Molecular examinations revealed that quercetin-PC at 200μM significantly activated Nrf2 nuclear translocation and significantly enhanced the expression of target genes HO-1, NQO-1 and GCL by different folds at both mRNA and protein levels. Our current data collectively indicated that quercetin-PC had stronger protective effects against oxidative-induced damages in ARPE-19 cells, which was associated with activation of Nrf2 pathway and its target genes implicated in antioxidant defense. PMID:26643168

  5. Following the Viterbi Path to Deduce Flagellar Actin-Interacting Proteins of Leishmania spp.: Report on Cofilins and Twinfilins

    NASA Astrophysics Data System (ADS)

    Pacheco, Ana Carolina L.; Araújo, Fabiana F.; Kamimura, Michel T.; Medeiros, Sarah R.; Viana, Daniel A.; Oliveira, Fátima de Cássia E.; Filho, Raimundo Araújo; Costa, Marcília P.; Oliveira, Diana M.

    2007-11-01

    For performing vital cellular processes, such as motility, eukaryotic cells rely on the actin cytoskeleton, whose structure and dynamics are tightly controlled by a large number of actin-interacting (AIP) or actin-related/regulating (ARP) proteins. Trypanosomatid protozoa, such as Leishmania, rely on their flagellum for motility and sensory reception, which are believed to allow parasite migration, adhesion, invasion and even persistence on mammalian host tissues to cause disease. Actin can determine cell stiffness and transmit force during mechanotransduction, cytokinesis, cell motility and other cellular shape changes, while the identification and analyses of AIPs can help to improve understanding of their mechanical properties on physiological architectures, such as the present case regarding Leishmania flagellar apparatus. This work conveniently apply bioinformatics tools in some refined pattern recognition techniques (such as hidden Markov models (HMMs) through the Viterbi algorithm/path) in order to improve the recognition of actin-binding/interacting activity through identification of AIPs in genomes, transcriptomes and proteomes of Leishmania species. We here report cofilin and twinfilin as putative components of the flagellar apparatus, a direct bioinformatics contribution in the secondary annotation of Leishmania and trypanosomatid genomes.

  6. SCARN a Novel Class of SCAR Protein That Is Required for Root-Hair Infection during Legume Nodulation.

    PubMed

    Qiu, Liping; Lin, Jie-Shun; Xu, Ji; Sato, Shusei; Parniske, Martin; Wang, Trevor L; Downie, J Allan; Xie, Fang

    2015-10-01

    Rhizobial infection of legume root hairs requires a rearrangement of the actin cytoskeleton to enable the establishment of plant-made infection structures called infection threads. In the SCAR/WAVE (Suppressor of cAMP receptor defect/WASP family verpolin homologous protein) actin regulatory complex, the conserved N-terminal domains of SCAR proteins interact with other components of the SCAR/WAVE complex. The conserved C-terminal domains of SCAR proteins bind to and activate the actin-related protein 2/3 (ARP2/3) complex, which can bind to actin filaments catalyzing new actin filament formation by nucleating actin branching. We have identified, SCARN (SCAR-Nodulation), a gene required for root hair infection of Lotus japonicus by Mesorhizobium loti. Although the SCARN protein is related to Arabidopsis thaliana SCAR2 and SCAR4, it belongs to a distinct legume-sub clade. We identified other SCARN-like proteins in legumes and phylogeny analyses suggested that SCARN may have arisen from a gene duplication and acquired specialized functions in root nodule symbiosis. Mutation of SCARN reduced formation of infection-threads and their extension into the root cortex and slightly reduced root-hair length. Surprisingly two of the scarn mutants showed constitutive branching of root hairs in uninoculated plants. However we observed no effect of scarn mutations on trichome development or on the early actin cytoskeletal accumulation that is normally seen in root hair tips shortly after M. loti inoculation, distinguishing them from other symbiosis mutations affecting actin nucleation. The C-terminal domain of SCARN binds to ARPC3 and ectopic expression of the N-terminal SCAR-homology domain (but not the full length protein) inhibited nodulation. In addition, we found that SCARN expression is enhanced by M. loti in epidermal cells and that this is directly regulated by the NODULE INCEPTION (NIN) transcription factor. PMID:26517270

  7. SCARN a Novel Class of SCAR Protein That Is Required for Root-Hair Infection during Legume Nodulation

    PubMed Central

    Qiu, Liping; Lin, Jie-shun; Xu, Ji; Sato, Shusei; Parniske, Martin; Wang, Trevor L.; Downie, J. Allan; Xie, Fang

    2015-01-01

    Rhizobial infection of legume root hairs requires a rearrangement of the actin cytoskeleton to enable the establishment of plant-made infection structures called infection threads. In the SCAR/WAVE (Suppressor of cAMP receptor defect/WASP family verpolin homologous protein) actin regulatory complex, the conserved N-terminal domains of SCAR proteins interact with other components of the SCAR/WAVE complex. The conserved C-terminal domains of SCAR proteins bind to and activate the actin-related protein 2/3 (ARP2/3) complex, which can bind to actin filaments catalyzing new actin filament formation by nucleating actin branching. We have identified, SCARN (SCAR-Nodulation), a gene required for root hair infection of Lotus japonicus by Mesorhizobium loti. Although the SCARN protein is related to Arabidopsis thaliana SCAR2 and SCAR4, it belongs to a distinct legume-sub clade. We identified other SCARN-like proteins in legumes and phylogeny analyses suggested that SCARN may have arisen from a gene duplication and acquired specialized functions in root nodule symbiosis. Mutation of SCARN reduced formation of infection-threads and their extension into the root cortex and slightly reduced root-hair length. Surprisingly two of the scarn mutants showed constitutive branching of root hairs in uninoculated plants. However we observed no effect of scarn mutations on trichome development or on the early actin cytoskeletal accumulation that is normally seen in root hair tips shortly after M. loti inoculation, distinguishing them from other symbiosis mutations affecting actin nucleation. The C-terminal domain of SCARN binds to ARPC3 and ectopic expression of the N-terminal SCAR-homology domain (but not the full length protein) inhibited nodulation. In addition, we found that SCARN expression is enhanced by M. loti in epidermal cells and that this is directly regulated by the NODULE INCEPTION (NIN) transcription factor. PMID:26517270

  8. Astaxanthin protects ARPE-19 cells from oxidative stress via upregulation of Nrf2-regulated phase II enzymes through activation of PI3K/Akt

    PubMed Central

    Li, Zhongrui; Dong, Xin; Liu, Hongling; Chen, Xi; Shi, Huanqi; Fan, Yan; Hou, Dingshan

    2013-01-01

    Purpose Oxidative stress on retinal pigment epithelial (RPE) cells is thought to play a crucial role in the development and progression of age-related macular degeneration. Astaxanthin (AST) is a carotenoid that shows significant antioxidant properties. This study was designed to investigate the protective effect of AST on ARPE-19 cells against oxidative stress and the possible underlying mechanism. Methods ARPE-19 cells exposed to different doses of H2O2 were incubated with various concentrations of AST and cell viability subsequently detected with the (4-[3-[4-iodophenyl]-2–4(4-nitrophenyl)-2H-5- tetrazolio-1,3-benzene disulfonate]; WST-1) assay. The apoptosis rate and intracellular levels of reactive oxygen species (ROS) were measured with flow cytometry. NAD(P)H quinine oxidoreductase 1 (NQO1), hemeoxygenase-1 (HO-1), glutamate-cysteine ligase modifier subunit (GCLM), and glutamate-cysteine ligase catalytic subunit (GCLC) expression were examined with real-time PCR and western blotting. The nuclear localization of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) protein and the expression levels of cleaved caspase-3 and protein kinase B proteins were evaluated with western blotting. Results AST clearly reduced H2O2-induced cell viability loss, cell apoptosis, and intracellular generation of ROS. Furthermore, treatment with AST activated the Nrf2-ARE pathway by inducing Nrf2 nuclear localization. Consequently, Phase II enzymes NQO1, HO-1, GCLM, and GCLC mRNA and proteins were increased. AST inhibited expression of H2O2-induced cleaved caspase-3 protein. Activation of the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) pathway was involved in the protective effect of AST on the ARPE-19 cells. Conclusions AST protected ARPE-19 cells against H2O2-induced oxidative stress via Nrf2-mediated upregulation of the expression of Phase II enzymes involving the PI3K/Akt pathway. PMID:23901249

  9. Searching for Tidal Features in Galaxy Pair ARP 142

    NASA Astrophysics Data System (ADS)

    Ronca, Joseph; Domingue, Donovan L.

    2016-01-01

    We present the beginning of an ongoing research project to detect tidal features in galaxy pairs with the test case of ARP 142 (NGC 2936 & NGC 2937). Using the 0.6 meter telescope at the Pohl Observatory of Georgia College and State University, a series of sixty, fifteen second luminance exposures, were taken using an SBIG 9XE CCD. In order to reduce the background sky brightness, images were calibrated using standard techniques, as well as using additional flats created from nearby sections of the sky.

  10. The biocontrol bacterium Pseudomonas fluorescens Pf29Arp strain affects the pathogenesis-related gene expression of the take-all fungus Gaeumannomyces graminis var. tritici on wheat roots

    PubMed Central

    Daval, Stéphanie; Lebreton, Lionel; Gazengel, Kévin; Boutin, Morgane; Guillerm-Erckelboudt, Anne-Yvonne; Sarniguet, Alain

    2011-01-01

    The main effects of antagonistic rhizobacteria on plant pathogenic fungi are antibiosis, fungistasis or an indirect constraint through the induction of a plant defence response. To explore different biocontrol mechanisms, an in vitro confrontation assay was conducted with the rhizobacterium Pseudomonas fluorescens Pf29Arp as a biocontrol agent of the fungus Gaeumannomyces graminis var. tritici (Ggt) on wheat roots. In parallel with the assessment of disease extension, together with the bacterial and fungal root colonization rates, the transcript levels of candidate fungal pathogenicity and plant-induced genes were monitored during the 10-day infection process. The bacterial inoculation of wheat roots with the Pf29Arp strain reduced the development of Ggt-induced disease expressed as attack frequency and necrosis length. The growth rates of Ggt and Pf29Arp, monitored through quantitative polymerase chain reaction of DNA amounts with a part of the Ggt 18S rDNA gene and a specific Pf29Arp strain detection probe, respectively, increased throughout the interactions. Bacterial antagonism and colonization had no significant effect on root colonization by Ggt. The expression of fungal and plant genes was quantified in planta by quantitative reverse transcription-polymerase chain reaction during the interactions thanks to the design of specific primers and an innovative universal reference system. During the early stages of the tripartite interaction, several of the fungal genes assayed were down-regulated by Pf29Arp, including two laccases, a β-1,3-exoglucanase and a mitogen-activated protein kinase. The plant host glutathione-S-transferase gene was induced by Ggt alone and up-regulated by Pf29Arp bacteria in interaction with the pathogen. We conclude that Pf29Arp antagonism acts through the alteration of fungal pathogenesis and probably through the activation of host defences. PMID:21726382

  11. A Deep Arecibo Spectral Scan of Arp 220

    NASA Astrophysics Data System (ADS)

    Vick, Michelle; Ghosh, T.; Salter, C. J.; Minchin, R. F.

    2014-01-01

    A deep spectral scan of the prototype Ultra Luminous Infra-Red Galaxy (ULIRG), Arp 220, has been made over the frequency range 1.1 to 10.0 GHz using the 305-m Arecibo telescope. These new observations supersede a previous shallow scan of Arp 220 (Salter et al., 2008, Astron. J., 136, 389). The spectral lines seen in the previous scan were all re-detected with greatly improved signal-to-noise ratio. These lines include hydrogen cyanide (HCN v2=1) in absorption, formaldehyde (H2CO) in emission at 4.83 GHz, and hydroxyl (OH) in emission at 1.6 GHz and absorption at 4.7, 6.0 and 7.8 GHz. In addition, a large number of hydrogen recombination lines were detected, as was the H2CO line at 4.955 GHz, and two lines that are identified with excited transitions of methylidyne (CH) at 4.848 and 4.870 GHz. The identification of other possible detections is on-going.

  12. PWR Cross Section Libraries for ORIGEN-ARP

    SciTech Connect

    McGraw, Carolyn; Ilas, Germina

    2012-01-01

    New pressurized water reactor (PWR) cross-section libraries were generated for use with the ORIGEN-ARP depletion sequence in the SCALE nuclear analysis code system. These libraries are based on ENDF/B-VII nuclear data and were generated using the two-dimensional depletion sequence, TRITON/NEWT, in SCALE 6.1. The libraries contain multiple burnup-dependent cross-sections for seven PWR fuel designs, with enrichments ranging from 1.5 to 6 wt% 235U. The burnup range has been extended from the 72 GWd/MTU used in previous versions of the libraries to 90 GWd/MTU. Validation of the libraries using radiochemical assay measurements and decay heat measurements for PWR spent fuel showed good agreement between calculated and experimental data. Verification against detailed TRITON simulations for the considered assembly designs showed that depletion calculations performed in ORIGEN-ARP with the pre-generated libraries provide similar results as obtained with direct TRITON depletion, while greatly reducing the computation time.

  13. ARPES view of orbitally resolved quasiparticle lifetimes in iron pnictides

    NASA Astrophysics Data System (ADS)

    Brouet, Véronique; LeBoeuf, David; Lin, Ping-Hui; Mansart, Joseph; Taleb-Ibrahimi, Amina; Le Fèvre, Patrick; Bertran, François; Forget, Anne; Colson, Dorothée

    2016-02-01

    We study with angle-resolved photoemission spectroscopy (ARPES) the renormalization and quasiparticle lifetimes of the dx y and dx z/dy z orbitals in two iron pnictides, LiFeAs and Ba (Fe0.92Co0.08 )2As2 (Co8). We find that both quantities depend on orbital character rather than on the position on the Fermi surface (for example, hole or electron pocket). In LiFeAs, the renormalizations are larger for dx y, while they are similar for both types of orbitals in Co8. The most salient feature, which proved robust against all the ARPES caveats we could think of, is that the lifetimes for dx y exhibit a markedly different behavior than those for dx z/dy z. They have smaller values near EF and exhibit larger ω and temperature dependences. While the behavior of dx y is compatible with a Fermi-liquid description, that is not the case for dx z/dy z. This situation should have important consequences for the physics of iron pnictides, which have not been considered up to now. More generally, it raises interesting questions about how a Fermi-liquid regime can be established in a multiband system with small effective bandwidths.

  14. ARPES of single layer iron pnictide on STO

    NASA Astrophysics Data System (ADS)

    Shen, Zhi-Xun

    Quantum systems in confined geometries have been a very rich ground for discoveries. In this talk, I will discuss recent progresses in uncovering novel physics at ultra-thin limit, with focus on mono-unit-cell (UC) superconductor FeSe grown on SrTiO3, where the Cooper pairing temperature is reported to have dramatically enhanced from its bulk value of 8K to ~60K. Of interest are the cause of the enhanced pairing strength, and the nature of the superconducting state. We show angle-resolved photoemission spectroscopy (ARPES) data that provide clear evidence for strong cross-interface electron-phonon coupling in single UC limit, suggesting that pairing is significantly enhanced by the strong interface mode coupling. We will also show other results on the nature of the superconducting state in this system..

  15. P CYGNI PROFILES OF MOLECULAR LINES TOWARD ARP 220 NUCLEI

    SciTech Connect

    Sakamoto, Kazushi; Aalto, Susanne; Black, John H.; Conway, John E.; Costagliola, Francesco; Wilner, David J.; Peck, Alison B.; Spaans, Marco; Wang, Junzhi; Wiedner, Martina C.

    2009-08-01

    We report {approx}100 pc (0.''3) resolution observations of (sub)millimeter HCO{sup +} and CO lines in the ultraluminous infrared galaxy Arp 220. The lines peak at two merger nuclei, with HCO{sup +} being more spatially concentrated than CO. Asymmetric line profiles with blueshifted absorption and redshifted emission are discovered in HCO{sup +}(3-2) and (4-3) toward the two nuclei and in CO(3-2) toward one nucleus. We suggest that these P Cygni profiles are due to {approx}100 km s{sup -1} outward motion of molecular gas from the nuclei. This gas is most likely outflowing from the inner regions of the two nuclear disks rotating around individual nuclei, clearing the shroud around the luminosity sources there.

  16. A Focused, Hard X-Ray Look at Arp 299 with NuSTAR

    NASA Astrophysics Data System (ADS)

    Ptak, A.; Hornschemeier, A.; Zezas, A.; Lehmer, B.; Yukita, M.; Wik, D.; Antoniou, V.; Argo, M. K.; Ballo, L.; Bechtol, K.; Boggs, S.; Della Ceca, R.; Christensen, F. E.; Craig, W. W.; Hailey, C. J.; Harrison, F. A.; Krivonos, R.; Maccarone, T. J.; Stern, D.; Tatum, M.; Venters, T.; Zhang, W. W.

    2015-02-01

    We report on simultaneous observations of the local starburst system Arp 299 with NuSTAR and Chandra, which provides the first resolved images of this galaxy up to energies of ~45 keV. Fitting the 3-40 keV spectrum reveals a column density of N H ~ 4 × 1024 cm-2, characteristic of a Compton-thick active galactic nucleus (AGN), and a 10-30 keV luminosity of 1.2 × 1043 erg s-1. The hard X-rays detected by NuSTAR above 10 keV are centered on the western nucleus, Arp 299-B, which previous X-ray observations have shown to be the primary source of neutral Fe-K emission. Other X-ray sources, including Arp 299-A, the eastern nucleus also thought to harbor an AGN, as well as X-ray binaries, contribute <~ 10% to the 10-20 keV emission from the Arp 299 system. The lack of significant emission above 10 keV other than that attributed to Arp 299-B suggests that: (1) any AGN in Arp 299-A must be heavily obscured (N H > 1024 cm-2) or have a much lower luminosity than Arp 299-B and (2) the extranuclear X-ray binaries have spectra that cut-off above ~10 keV. Such soft spectra are characteristic of ultraluminous X-ray sources observed to date by NuSTAR.

  17. The plant pathogenic fungus Gaeumannomyces graminis var. tritici improves bacterial growth and triggers early gene regulations in the biocontrol strain Pseudomonas fluorescens Pf29Arp.

    PubMed

    Barret, M; Frey-Klett, P; Boutin, M; Guillerm-Erckelboudt, A-Y; Martin, F; Guillot, L; Sarniguet, A

    2009-01-01

    In soil, some antagonistic rhizobacteria contribute to reduce root diseases caused by phytopathogenic fungi. Direct modes of action of these bacteria have been largely explored; however, commensal interaction also takes place between these microorganisms and little is known about the influence of filamentous fungi on bacteria. An in vitro confrontation bioassay between the pathogenic fungus Gaeumannomyces graminis var. tritici (Ggt) and the biocontrol bacterial strain Pseudomonas fluorescens Pf29Arp was set up to analyse bacterial transcriptional changes induced by the fungal mycelium at three time-points of the interaction before cell contact and up until contact. For this, a Pf29Arp shotgun DNA microarray was constructed. Specifity of Ggt effect was assessed in comparison with one of two other filamentous fungi, Laccaria bicolor and Magnaporthe grisea. During a commensal interaction, Ggt increased the growth rate of Pf29Arp. Before contact, Ggt induced bacterial genes involved in mycelium colonization. At contact, genes encoding protein of stress response and a patatin-like protein were up-regulated. Among all the bacterial genes identified, xseB was specifically up-regulated at contact by Ggt but down-regulated by the other fungi. Data showed that the bacterium sensed the presence of the fungus early, but the main gene alteration occurred during bacterial-fungal cell contact. PMID:19121038

  18. Implications of the ISO LWS spectrum of the prototypical ultraluminous galaxy: ARP 220

    NASA Technical Reports Server (NTRS)

    Fischer, J.; Satyapal, S.; Luhman, M. L.; Melnick, G.; Cox, P.; Cernicharo, J.; Stacey, G. J.; Smith, H. A.; Lord, S. D.; Greenhouse, M. A.

    1997-01-01

    The low resolution far infrared spectrum of the galaxy Arp 220, obtained with the low wavelength spectrometer (LWS) onboard the Infrared Space Observatory (ISO), is presented. The spectrum is dominated by the OH, H2O, CH, NH3 and O I absorption lines. The upper limits on the far infrared fine structure lines indicate a softer radiation in Arp 220 than in starburst galaxies.

  19. Arp2/3 complex ATP hydrolysis promotes lamellipodial actin network disassembly but is dispensable for assembly

    PubMed Central

    Ingerman, Elena; Hsiao, Jennifer Ying

    2013-01-01

    We examined the role of ATP hydrolysis by the Arp2/3 complex in building the leading edge of a cell by studying the effects of hydrolysis defects on the behavior of the complex in the lamellipodial actin network of Drosophila S2 cells and in a reconstituted, in vitro, actin-based motility system. In S2 cells, nonhydrolyzing Arp2 and Arp3 subunits expanded and delayed disassembly of lamellipodial actin networks and the effect of mutant subunits was additive. Arp2 and Arp3 ATP hydrolysis mutants remained in lamellipodial networks longer and traveled greater distances from the plasma membrane, even in networks still containing wild-type Arp2/3 complex. In vitro, wild-type and ATP hydrolysis mutant Arp2/3 complexes each nucleated actin and built similar dendritic networks. However, networks constructed with Arp2/3 hydrolysis-defective mutants were more resistant to disassembly by cofilin. Our results indicate that ATP hydrolysis on both Arp2 and Arp3 contributes to dissociation of the complex from the actin network but is not strictly necessary for lamellipodial network disassembly. PMID:23439681

  20. Isoform diversity in the Arp2/3 complex determines actin filament dynamics.

    PubMed

    Abella, Jasmine V G; Galloni, Chiara; Pernier, Julien; Barry, David J; Kjær, Svend; Carlier, Marie-France; Way, Michael

    2016-01-01

    The Arp2/3 complex consists of seven evolutionarily conserved subunits (Arp2, Arp3 and ARPC1-5) and plays an essential role in generating branched actin filament networks during many different cellular processes. In mammals, however, the ARPC1 and ARPC5 subunits are each encoded by two isoforms that are 67% identical. This raises the possibility that Arp2/3 complexes with different properties may exist.  We found that Arp2/3 complexes containing ARPC1B and ARPC5L are significantly better at promoting actin assembly than those with ARPC1A and ARPC5, both in cells and in vitro. Branched actin networks induced by complexes containing ARPC1B or ARPC5L are also disassembled ∼2-fold slower than those formed by their counterparts. This difference reflects the ability of cortactin to stabilize ARPC1B- and ARPC5L- but not ARPC1A- and ARPC5-containing complexes against coronin-mediated disassembly. Our observations demonstrate that the Arp2/3 complex in higher eukaryotes is actually a family of complexes with different properties. PMID:26655834

  1. Identification of early salt stress responsive proteins in seedling roots of upland cotton (Gossypium hirsutum L.) employing iTRAQ-based proteomic technique

    PubMed Central

    Li, Wu; Zhao, Fu'an; Fang, Weiping; Xie, Deyi; Hou, Jianan; Yang, Xiaojie; Zhao, Yuanming; Tang, Zhongjie; Nie, Lihong; Lv, Shuping

    2015-01-01

    Soil salinity is a major abiotic stress that limits plant growth and agricultural productivity. Upland cotton (Gossypium hirsutum L.) is highly tolerant to salinity; however, large-scale proteomic data of cotton in response to salt stress are still scant. Here, an isobaric tag for relative and absolute quantitation (iTRAQ)-based proteomic technique was employed to identify the early differentially expressed proteins (DEPs) from salt-treated cotton roots. One hundred and twenty-eight DEPs were identified, 76 of which displayed increased abundance and 52 decreased under salt stress conditions. The majority of the proteins have functions related to carbohydrate and energy metabolism, transcription, protein metabolism, cell wall and cytoskeleton metabolism, membrane and transport, signal transduction, in addition to stress and defense. It is worth emphasizing that some novel salt-responsive proteins were identified, which are involved in cell cytoskeleton metabolism (actin-related protein2, ARP2, and fasciclin-like arabinogalactan proteins, FLAs), membrane transport (tonoplast intrinsic proteins, TIPs, and plasma membrane intrinsic proteins, PIPs), signal transduction (leucine-rich repeat receptor-like kinase encoding genes, LRR-RLKs) and stress responses (thaumatin-like protein, TLP, universal stress protein, USP, dirigent-like protein, DIR, desiccation-related protein PCC13-62). High positive correlation between the abundance of some altered proteins (superoxide dismutase, SOD, peroxidase, POD, glutathione S-transferase, GST, monodehydroascorbate reductase, MDAR, and malate dehydrogenase, MDH) and their enzyme activity was evaluated. The results demonstrate that the iTRAQ-based proteomic technique is reliable for identifying and quantifying a large number of cotton root proteins. qRT-PCR was used to study the gene expression levels of the five above-mentioned proteins; four patterns are consistent with those of induced protein. These results showed that the proteome

  2. Star clusters in the interacting galaxy system Arp 284

    NASA Astrophysics Data System (ADS)

    Peterson, Bradley W.; Struck, Curtis; Smith, Beverly J.; Hancock, Mark

    2009-12-01

    We present results from a study of protoglobular cluster candidates in the interacting galaxy system Arp 284 (NGC 7714/5) using data from the Hubble Space Telescope (HST). Previous studies of the Antennae and M51 have suggested that the majority of young massive star clusters dissolve within 20 Myr due to mass loss. We use the evolutionary synthesis code STARBURST99 to estimate ages and extinctions for approximately 175 clusters visible with HST. We also use lower resolution Galaxy Evolution Explorer and ground-based Hα data to estimate the ages of the giant HII regions in which these clusters are found, and compare the Spitzer colours of these HII regions to those of star-forming regions in other interacting systems. The ages are also used to aid in the interpretation of Chandra X-ray data. Clusters in the tidal tails of NGC 7714 are generally found to have ages less than 20 Myr, though observational limits make the significance of this result uncertain. Older clusters, though not numerous, have nearly the same spatial distribution within the imaged portion of NGC 7714 as young clusters. The cluster population in the bridge connecting the two galaxies appears to be older, but the data in this part of the system are too limited to draw firm conclusions. The ages of the giant HII regions in NGC 7714 are generally older than those of their constituent clusters, possibly indicating that the young clusters we detect are surrounded by their dispersed predecessors.

  3. Zeaxanthin and α-tocopherol reduce the inhibitory effects of photodynamic stress on phagocytosis by ARPE-19 cells.

    PubMed

    Olchawa, Magdalena M; Herrnreiter, Anja M; Pilat, Anna K; Skumatz, Christine M B; Niziolek-Kierecka, Magdalena; Burke, Janice M; Sarna, Tadeusz J

    2015-12-01

    Zeaxanthin and α-tocopherol have been previously shown to efficiently protect liposomal membrane lipids against photosensitized peroxidation, and to protect cultured RPE cells against photodynamic killing. Here the protective action of combined zeaxanthin and α-tocopherol was analyzed in ARPE-19 cells subjected to photodynamic (PD) stress mediated by rose Bengal (RB) or merocyanine-540 (MC-540) at sub-lethal levels. Stress-induced cytotoxicity was analyzed by the MTT assay. The peroxidation of membrane lipids was determined by HPLC-EC (Hg) measurements of cholesterol hydroperoxides using cholesterol as a mechanistic reporter molecule. The specific phagocytosis of FITC-labeled photoreceptor outer segments (POS) isolated from bovine retinas was measured by flow cytometry, and the levels of phagocytosis receptor proteins αv integrin subunit, β5 integrin subunit and MerTK were quantified by Western blot analysis. Cytotoxicity measures confirmed that PD stress levels used for phagocytosis analysis were sub-lethal and that antioxidant supplementation protected against higher, lethal PD doses. Sub-lethal PD stress mediated by both photosensitizers induced the accumulation of 5α-OOH and 7α/β-OOH cholesterol hydroperoxides and the addition of the antioxidants substantially inhibited their accumulation. Antioxidant delivery prior to PD stress also reduced the inhibitory effect of stress on POS phagocytosis and partially reduced the stress-induced diminution of phagocytosis receptor proteins. The use of a novel model system where oxidative stress was induced at sub-lethal levels enable observations that would not be detectable using lethal stress models. Moreover, novel observations about the protective effects of zeaxanthin and α-tocopherol on photodynamic damage to ARPE-19 cell membranes and against reductions in the abundance of receptor proteins involved in POS phagocytosis, a process essential for photoreceptor survival, supports the importance of the

  4. Zeaxanthin and α-tocopherol reduce the inhibitory effects of photodynamic stress on phagocytosis by ARPE-19 cells

    PubMed Central

    Olchawa, Magdalena M.; Herrnreiter, Anja M.; Pilat, Anna K.; Skumatz, Christine M. B.; Niziolek-Kierecka, Magdalena; Burke, Janice M.; Sarna, Tadeusz J.

    2016-01-01

    Zeaxanthin and α-tocopherol have been previously shown to efficiently protect liposomal membrane lipids against photosensitized peroxidation, and to protect cultured RPE cells against photodynamic killing. Here the protective action of combined zeaxanthin and α-tocopherol was analyzed in ARPE-19 cells subjected to photodynamic (PD) stress mediated by rose Bengal (RB) or merocyanine-540 (MC-540) at sub-lethal levels. Stress-induced cytotoxicity was analyzed by the MTT assay. The peroxidation of membrane lipids was determined by HPLC-EC(Hg) measurements of cholesterol hydroperoxides using cholesterol as a mechanistic reporter molecule. The specific phagocytosis of FITC-labeled photoreceptor outer segments (POS) isolated from bovine retinas was measured by flow cytometry, and the levels of phagocytosis receptor proteins αv integrin subunit, β5 integrin subunit and MerTK were quantified by Western blot analysis. Cytotoxicity measures confirmed that PD stress levels used for phagocytosis analysis were sub-lethal and that antioxidant supplementation protected against higher, lethal PD doses. Sub-lethal PD stress mediated by both photosensitizers induced the accumulation of 5α-OOH and 7α/β-OOH cholesterol hydroperoxides and the addition of the antioxidants substantially inhibited their accumulation. Antioxidant delivery prior to PD stress also reduced the inhibitory effect of stress on POS phagocytosis and partially reduced the stress-induced diminution of phagocytosis receptor proteins. The use of a novel model system where oxidative stress was induced at sub-lethal levels enable observations that would not be detectable using lethal stress models. Moreover, novel observations about the protective effects of zeaxanthin and α-tocopherol on photodynamic damage to ARPE-19 cell membranes and against reductions in the abundance of receptor proteins involved in POS phagocytosis, a process essential for photoreceptor survival, supports the importance of the antioxidants

  5. CO aperture synthesis of NGC 4038/9 (ARP 244)

    NASA Technical Reports Server (NTRS)

    Stanford, S. A.; Sanders, D. B.; Sargent, A. I.; Scoville, N. Z.

    1990-01-01

    Researchers present high-resolution (approx. 6 seconds) CO observations of the merging galaxies NGC 4038/9 made with the Owens Valley Radio Observatory (OVRO) Millimeter Wave Interferometer. The CO observations of Arp 244 were obtained between April and June 1988 using the OVRO Millimeter Wave Interferometer. Two fields with phase centers near the NGC 4039 nucleus and near the NGC 4038 nucleus were observed. The size of the synthesized beam is approximately 6.5 x 7 seconds at PA=72 degrees. The rms in a single cleaned channel map is 0.06 Jy beam(exp -1), corresponding to a brightness temperature of 0.12 K over the synthesized beam. Contour maps of the integrated CO intensity for both interferometer fields are shown. Three CO concentrations are evident. Two are centered near the nuclei of NGC 4038 and NGC 4039, closely correlated with H alpha and radio continuum maxima. A third CO emission region lies about 25 seconds northeast of the NGC 4039 nucleus. A number of radio continuum, H alpha, and 10 micron emission knots appear in this region. The total integrated intensity at the northern nuclear source, 302 K km/s, leads to a molecular mass of 8.3 by 10 to the 8th power solar mass assuming a Galactic CO to H2 conversion factor of 3.0 x 10 to the 20th power H2 cm(-2) (K km/s)(-1). The integrated CO intensity of the southern nuclear source leads to a molecular mass of 2.4 x 10 to the 8th solar mass. The extranuclear CO concentration contains 1.2 x 10 to the 9th power solar mass of molecular gas, extending over 170 km/s, and is resolved in a number of channels. Its large size, mass, and morphology strongly suggest that it is an agglomeration of several clumps.

  6. An infrared study of starbursts in the interacting galaxy pair Arp 299 (NGC 3690+IC 694)

    SciTech Connect

    Nakagawa, Takao; Nagata, Tetsuya; Geballe, T.R.; Okuda, Haruyuki; Shibai, Hiroshi; Tokyo Univ.; Kyoto Univ.; Joint Astronomy Center, Hilo, HI; Institute of Space and Astronautical Science, Sagamihara )

    1989-05-01

    Extensive infrared observations have been obtained of the three active regions in Arp 299. Multiaperture JHK photometry reveals that the colors of the three regions are totally different from each other, and that there are very red nuclei smaller than 4 arcsec in two of them. Multiaperture spectroscopy of the Br-gamma and the shock-excited H2 lines shows that both the atomic and molecular lines are spatially extended, indicating that Arp 299 is undergoing an active episode of star formation not only in its nuclei but also well outside of them. Although there is some evidence that suggests the presence of a compact, active galactic nucleus, a simple starburst model can explain the bolometric luminosities, production rates of ionizing photons, and H24 line luminosities of each active region in Arp 299. However, each starburst cannot last longer than 10 to the 8th yr. 56 refs.

  7. The Far-Infrared Spectrum of Arp 220

    NASA Technical Reports Server (NTRS)

    Gonzalez-Alfonso, Eduardo; Smith, Howard A.; Fischer, Jacqueline; Cernicharo, Jose

    2005-01-01

    ISO/LWS grating observations of the ultraluminous infrared galaxy Arp 220 shows absorption in molecular lines of OH, H(sub 2)O, CH, NH, and NH(sub 3), as well as in the [O I] 63 micron line and emission in the [C II] 158 micron line. We have modeled the continuum and the emission/absorption of all observed features by means of a non-local radiative transfer code. The continuum from 25 to 1300 microns is modeled as a warm (106 K) nuclear region that is optically thick in the far-infrared, attenuated by an extended region (size 2") that is heated mainly through absorption of nuclear infrared radiation. The molecular absorption in the nuclear region is characterized by high excitation due to the high infrared radiation density. The OH column densities are high toward the nucleus (2 - 6 x 10(exp 17) cm(exp -2)) and the extended region (approximately 2 x 10(exp 17) cm(exp -2)). The H(sub 2)O column density is also high toward the nucleus (2 - 10 x 10(exp 17) cm(exp -2)) and lower in the extended region. The column densities in a halo that accounts for the absorption by the lowest lying levels are similar to what are found in the diffuse clouds toward the star forming regions in the Sgr B2 molecular cloud complex near the Galactic Center. Most notable are the high column densities found for NH and NH(sub 3) toward the nucleus, with values of approximately 1.5 x 10(exp 16) cm(exp -2) and approximately 3 x 10(exp 16) cm(exp -2), respectively, whereas the NH(sub 2) column density is lower than approximately 2 x 10(exp 15) cm(exp -2). A combination of PDRs in the extended region and hot cores with enhanced H(sub 2)O photodissociation and a possible shock contribution in the nuclei may explain the relative column densities of OH and H(sub 2)O, whereas the nitrogen chemistry may be strongly affected by cosmic ray ionization. The [C II] 158 micron line is well reproduced by our models and its deficit relative to the CII/FIR ratio in normal and starburst galaxies is suggested to

  8. The Far-Infrared Spectrum of Arp 220

    NASA Technical Reports Server (NTRS)

    Gonzalez-Alfonso, Eduardo; Smith, Howard A.; Fischer, Jacqueline; Cernicharo, Jose

    2004-01-01

    ISO/LWS grating observations of the ultraluminous infrared galaxy Arp 220 shows absorption in molecular lines of OH, H 2 0 , CH, NH, and "3, well as in the [0 I] 63 pm line and emission in the [C 111 158 pm line. We have modeled the continuum and the emission/absorption of all observed features by means of a non-local radiative transfer code. The continuum from 25 to 1300 pm is modeled AS A WARM (106 K) NUCLEAR REGION THAT IS OPTICALLY THICK IN THE FAR-INFRARED, attenuated by an extended region (size 2") that is heated mainly through absorption of nuclear infrared radiation. The molecular absorption in the nuclear region is characterized by high excitation due to the high infrared radiation density. The OH column densities are high toward the nucleus and the extended region (about 2 x 10 sup 17 cm sup-2). The H2O column density is also high toward the nucleus (2 - 10 x 1017 cm-2) and lower in the extended region. The column densities in a halo that accounts for the absorption by the lowest lying levels are similar to what are found in the diffuse clouds toward the star forming regions in the Sgr B2 molecular cloud complex near the Galactic Center. Most notable are the high column densities found for NH and NH3 toward the nucleus, with values of about 1.5 x 10supl6 cmsup-2 and about 3 x 10supl6 cmsup-2, respectively, whereas the NH2 column density is lower than about 2 x 10sup15 cmsup-2. A combination of PDRs in the extended region and hot cores with enhanced H20 photodissociation and a possible shock contribution in the nuclei may explain the relative column densities of OH and H20, whereas the nitrogen chemistry may be strongly affected by cosmic ray ionization. The [C II] 158 pm line is well reproduced by our models and its "deficit" relative to the CII/FIR ratio in normal and starburst galaxies is suggested to be mainly a consequence of the dominant non-PDR component of far- infrared radiation, ALTHOUGH OUR MODELS ALONE CANNOT RULE OUT EXTINCTION EFFECTS IN THE

  9. Hubble Space Telescope Planetary Camera observations of Arp 220

    NASA Technical Reports Server (NTRS)

    Shaya, Edward J.; Dowling, Daniel M.; Currie, Douglas G.; Faber, S. M.; Groth, Edward J.

    1994-01-01

    Planetary Camera images of peculiar galaxy Arp 220 taken with V, R, and I band filters reveal a very luminous object near the position of the western radio continuum source, assumed to be the major nucleus, ans seven lesser objects within 2 sec of this position. The most luminous object is formally coincident with the radio source to within the errors of Hubble Space Telescope (HST) pointing accuracy, but we have found an alternate, more compelling alignment of maps in which the eastern radio source coincides with one of the lesser objects and the OH radio sources reside near the surfaces of other optical objects. The proposed centering places the most luminous object 150 pc (0.4 sec) away from the western radio source. We explore the possibilities that the objects are either holes in the dense dust distribution, dusty clouds reflecting a hidden bright nucleus, or associations of bright young stars. We favor the interpretation that at least the brightest two objects are massive young star associations with luminosities 10(exp 9) to 10(exp 11) solar luminosity, but highly extinguished by intervening dust. These massive associations should fall into the nucleus on a time scale of 10(exp 8) yr. About 10% of the enigmatic far-IR flux arises from the observed objects. In addition, if the diffuse starlight out to a radius of 8 sec is dominated by stars with typical ages of order 10(exp 8) yr (the time since the alleged merger of two galaxies), as indicated by the blue colors at larger radius, then the lower limit to the reradiation of diffuse starlight contributes 3 x 10(exp 11) solar luminosity to the far-infrared flux, or greater than or equal to 25% of the total far-IR flux. Three additional bright objects (M(sub V) approximately equals -13) located about 6 sec from the core are likely young globular clusters, but any of these could be recently exploded supernovae instead. The expected supernovae rate, if the dominant energy source is young stars, is about one per

  10. Angle-resolved photoemission spectroscopy (ARPES) studies of cuprate superconductors

    SciTech Connect

    Palczewski, Ari Deibert

    2010-01-01

    This dissertation is comprised of three different angle-resolved photoemission spectroscopy (ARPES) studies on cuprate superconductors. The first study compares the band structure from two different single layer cuprates Tl2Ba2CuO6+δ (Tl2201) Tc, max ≈ 95 K and (Bi 1.35Pb0.85)(Sr1.47La0.38)CuO6+δ (Bi2201) Tc, max ≈ 35 K. The aim of the study was to provide some insight into the reasons why single layer cuprate's maximum transition temperatures are so different. The study found two major differences in the band structure. First, the Fermi surface segments close to (π,0) are more parallel in Tl2201 than in Bi2201. Second, the shadow band usually related to crystal structure is only present in Bi2201, but absent in higher Tc Tl2201. The second study looks at the different ways of doping Bi2Sr2CaCu2O8+δ (Bi2212) in-situ by only changing the post bake-out vacuum conditions and temperature. The aim of the study is to systematically look into the generally overlooked experimental conditions that change the doping of a cleaved sample in ultra high vacuum (UHV) experiments. The study found two major experimental facts. First, in inadequate UHV conditions the carrier concentration of Bi2212 increases with time, due to the absorption of oxygen from CO2/CO molecules, prime contaminants present in UHV systems. Second, in a very clean UHV system at elevated temperatures (above about 200 K), the carrier concentration decreases due to the loss of oxygen atoms from the Bi-O layer. The final study probed the particle-hole symmetry of the pseudogap phase in high temperature superconducting cuprates by looking at the thermally excited bands above the Fermi level. The data showed a particle-hole symmetric pseudogap which symmetrically closes away from the nested FS before the node. The data is consistent

  11. OrigenArp Primer: How to Perform Isotopic Depletion and Decay Calculations with SCALE/ORIGEN

    SciTech Connect

    Bowman, Stephen M; Gauld, Ian C

    2010-08-01

    The SCALE (Standardized Computer Analyses for Licensing Evaluation) computer software system developed at Oak Ridge National Laboratory is widely used and accepted around the world for nuclear analyses. ORIGEN-ARP is a SCALE isotopic depletion and decay analysis sequence used to perform point-depletion calculations with the well-known ORIGEN-S code using problem-dependent cross sections. Problem-dependent cross-section libraries are generated using the ARP (Automatic Rapid Processing) module using an interpolation algorithm that operates on pre-generated libraries created for a range of fuel properties and operating conditions. Methods are provided in SCALE to generate these libraries using one-, two-, and three-dimensional transport codes. The interpolation of cross sections for uranium-based fuels may be performed for the variables burnup, enrichment, and water density. An option is also available to interpolate cross sections for mixed-oxide (MOX) fuels using the variables burnup, plutonium content, plutonium isotopic vector, and water moderator density. This primer is designed to help a new user understand and use ORIGEN-ARP with the OrigenArp Windows graphical user interface in SCALE. It assumes that the user has a college education in a technical field. There is no assumption of familiarity with nuclear depletion codes in general or with SCALE/ORIGEN-ARP in particular. The primer is based on SCALE 6 but should be applicable to earlier or later versions of SCALE. Information is included to help new users, along with several sample problems that walk the user through the different input forms and menus and illustrate the basic features. References to related documentation are provided. The primer provides a starting point for the nuclear analyst who uses SCALE/ORIGEN-ARP. Complete descriptions are provided in the SCALE documentation. Although the primer is self-contained, it is intended as a companion volume to the SCALE documentation. The SCALE Manual is

  12. Arp2/3 complex-dependent actin networks constrain myosin II function in driving retrograde actin flow.

    PubMed

    Yang, Qing; Zhang, Xiao-Feng; Pollard, Thomas D; Forscher, Paul

    2012-06-25

    The Arp2/3 complex nucleates actin filaments to generate networks at the leading edge of motile cells. Nonmuscle myosin II produces contractile forces involved in driving actin network translocation. We inhibited the Arp2/3 complex and/or myosin II with small molecules to investigate their respective functions in neuronal growth cone actin dynamics. Inhibition of the Arp2/3 complex with CK666 reduced barbed end actin assembly site density at the leading edge, disrupted actin veils, and resulted in veil retraction. Strikingly, retrograde actin flow rates increased with Arp2/3 complex inhibition; however, when myosin II activity was blocked, Arp2/3 complex inhibition now resulted in slowing of retrograde actin flow and veils no longer retracted. Retrograde flow rate increases induced by Arp2/3 complex inhibition were independent of Rho kinase activity. These results provide evidence that, although the Arp2/3 complex and myosin II are spatially segregated, actin networks assembled by the Arp2/3 complex can restrict myosin II-dependent contractility with consequent effects on growth cone motility. PMID:22711700

  13. The flavonoid, eriodictyol, induces long-term protection in ARPE-19 cells through its effects on Nrf2 activation and phase II gene expression

    PubMed Central

    Johnson, Jennifer; Maher, Pamela

    2009-01-01

    Purpose Eriodictyol, a flavonoid found in citrus fruits, is among the most potent compounds reported to protect human RPE cells from oxidative stress-induced cell death. In the present study, we determined whether eriodictyol-induced phase II protein expression further enhances the resistance of human ARPE-19 cells to oxidative stress. Methods We analyzed the ability of eriodictyol to activate Nrf2 and induce the phase II proteins, heme-oxygenase (HO-1), NAD(P)H: quinone oxidoreductase 1 (NQO-1), and the cellular antioxidant glutathione, (GSH). We performed cytoprotection assays in ARPE-19 cells that were overexpressing HO-1 or NQO-1. We compared cell survival after short-term and long-term eriodictyol treatment and tested the mechanism of protection using a dominant negative Nrf2 and an shRNA specific for HO-1. Results We demonstrate that eriodictyol induces the nuclear translocation of Nrf2, enhances the expression of HO-1 and NQO-1, and increases the levels of intracellular glutathione. We show that ARPE-19 cells that overexpress HO-1 or NQO-1 are more resistant to oxidative stress-induced cell death than control cells. We demonstrate that eriodictyol induces long-term protection that is significantly greater than its short-term protection, and this effect is correlated temporally with both the activation of Nrf2 and the induction of phase II enzymes. We demonstrate that this effect can be blocked with the use of a dominant negative to Nrf2 and an shRNA specific to HO-1. Conclusions These findings indicate the greatest benefit from eriodictyol may be its ability to regulate gene expression and enhance multiple cellular defenses to oxidative injury. PMID:19117929

  14. A Role for Myosin-I in Actin Assembly through Interactions with Vrp1p, Bee1p, and the Arp2/3 Complex

    PubMed Central

    Evangelista, Marie; Klebl, Bert M.; Tong, Amy H.Y.; Webb, Bradley A.; Leeuw, Thomas; Leberer, Ekkehard; Whiteway, Malcolm; Thomas, David Y.; Boone, Charles

    2000-01-01

    Type I myosins are highly conserved actin-based molecular motors that localize to the actin-rich cortex and participate in motility functions such as endocytosis, polarized morphogenesis, and cell migration. The COOH-terminal tail of yeast myosin-I proteins, Myo3p and Myo5p, contains an Src homology domain 3 (SH3) followed by an acidic domain. The myosin-I SH3 domain interacted with both Bee1p and Vrp1p, yeast homologues of human WASP and WIP, adapter proteins that link actin assembly and signaling molecules. The myosin-I acidic domain interacted with Arp2/3 complex subunits, Arc40p and Arc19p, and showed both sequence similarity and genetic redundancy with the COOH-terminal acidic domain of Bee1p (Las17p), which controls Arp2/3-mediated actin nucleation. These findings suggest that myosin-I proteins may participate in a diverse set of motility functions through a role in actin assembly. PMID:10648568

  15. MicroRNA-30b-Mediated Regulation of Catalase Expression in Human ARPE-19 Cells

    PubMed Central

    Haque, Rashidul; Chun, Eugene; Howell, Jennifer C.; Sengupta, Trisha; Chen, Dan; Kim, Hana

    2012-01-01

    Background Oxidative injury to retinal pigment epithelium (RPE) and retinal photoreceptors has been linked to a number of retinal diseases, including age-related macular degeneration (AMD). Reactive oxygen species (ROS)-mediated gene expression has been extensively studied at transcriptional levels. Also, the post-transcriptional control of gene expression at the level of translational regulation has been recently reported. However, the microRNA (miRNA/miR)-mediated post-transcriptional regulation in human RPE cells has not been thoroughly looked at. Increasing evidence points to a potential role of miRNAs in diverse physiological processes. Methodology/Principal Findings We demonstrated for the first time in a human retinal pigment epithelial cell line (ARPE-19) that the post-transcriptional control of gene expression via miRNA modulation regulates human catalase, an important and potent component of cell's antioxidant defensive network, which detoxifies hydrogen peroxide (H2O2) radicals. Exposure to several stress-inducing agents including H2O2 has been reported to alter miRNA expression profile. Here, we demonstrated that a sublethal dose of H2O2 (200 µM) up-regulated the expression of miR-30b, a member of the miR-30 family, which inhibited the expression of endogenous catalase both at the transcript and protein levels. However, antisense (antagomirs) of miR-30b was not only found to suppress the miR-30b mimics-mediated inhibitions, but also to dramatically increase the expression of catalase even under an oxidant environment. Conclusions/Significance We propose that a microRNA antisense approach could enhance cytoprotective mechanisms against oxidative stress by increasing the antioxidant defense system. PMID:22880027

  16. Differential analyses of major allergen proteins in wild-type rice and rice producing a fragment of anti-rotavirus antibody.

    PubMed

    Yuki, Yoshikazu; Kurokawa, Shiho; Kozuka-Hata, Hiroko; Tokuhara, Daisuke; Mejima, Mio; Kuroda, Masaharu; Oyama, Masaaki; Nishimaki-Mogami, Tomoko; Teshima, Reiko; Kiyono, Hiroshi

    2016-04-01

    To develop oral antibody therapy against rotavirus infection, we previously produced a recombinant fragment of llama heavy-chain antibody to rotavirus (ARP1) in rice seeds (MucoRice-ARP1). We intend to use a purification-free rice powder for clinical application but needed to check whether MucoRice-ARP1 had increased levels of known allergen proteins. For this purpose, we used two-dimensional fluorescence difference gel electrophoresis to compare the allergen protein levels in MucoRice-ARP1 and wild-type rice. We detected no notable differences, except in the levels of α-amylase/trypsin inhibitor-like family proteins. Because by this approach we could not completely separate ARP1 from the proteins of this family, we confirmed the absence of changes in the levels of these allergens by using shotgun mass spectrometry as well as immunoblot. By using immunoelectron microscopy, we also showed that RAG2, a member of the α-amylase/trypsin inhibitor-like protein family, was relocated from protein bodies II to the plasma membrane or cell wall in MucoRice-ARP1 seed. The relocation did not affect the level of RAG2. We demonstrated that most of the known rice allergens were not considerably upregulated by the genetic modification in MucoRice-ARP1. Our data suggest that MucoRice-ARP1 is a potentially safe oral antibody for clinical application. PMID:26851506

  17. Crucial roles of the Arp2/3 complex during mammalian corticogenesis

    PubMed Central

    Wang, Pei-Shan; Chou, Fu-Sheng; Ramachandran, Sreekumar; Xia, Sheng; Chen, Huei-Ying; Guo, Fengli; Suraneni, Praveen; Maher, Brady J.

    2016-01-01

    The polarity and organization of radial glial cells (RGCs), which serve as both stem cells and scaffolds for neuronal migration, are crucial for cortical development. However, the cytoskeletal mechanisms that drive radial glial outgrowth and maintain RGC polarity remain poorly understood. Here, we show that the Arp2/3 complex – the unique actin nucleator that produces branched actin networks – plays essential roles in RGC polarity and morphogenesis. Disruption of the Arp2/3 complex in murine RGCs retards process outgrowth toward the basal surface and impairs apical polarity and adherens junctions. Whereas the former is correlated with an abnormal actin-based leading edge, the latter is consistent with blockage in membrane trafficking. These defects result in altered cell fate, disrupted cortical lamination and abnormal angiogenesis. In addition, we present evidence that the Arp2/3 complex is a cell-autonomous regulator of neuronal migration. Our data suggest that Arp2/3-mediated actin assembly might be particularly important for neuronal cell motility in a soft or poorly adhesive matrix environment. PMID:27385014

  18. ALMA Imaging of HCN, CS, and Dust in Arp 220 and NGC 6240

    NASA Astrophysics Data System (ADS)

    Scoville, Nick; Sheth, Kartik; Walter, Fabian; Manohar, Swarnima; Zschaechner, Laura; Yun, Min; Koda, Jin; Sanders, David; Murchikova, Lena; Thompson, Todd; Robertson, Brant; Genzel, Reinhard; Hernquist, Lars; Tacconi, Linda; Brown, Robert; Narayanan, Desika; Hayward, Christopher C.; Barnes, Joshua; Kartaltepe, Jeyhan; Davies, Richard; van der Werf, Paul; Fomalont, Edward

    2015-02-01

    We report ALMA Band 7 (350 GHz) imaging at 0.''4-0.''6 resolution and Band 9 (696 GHz) at ~0.''25 resolution of the luminous IR galaxies Arp 220 and NGC 6240. The long wavelength dust continuum is used to estimate interstellar medium masses for Arp 220 east and west and NGC 6240 of 1.9, 4.2, and 1.6 × 109 M ⊙within radii of 69, 65, and 190 pc. The HCN emission was modeled to derive the emissivity distribution as a function of radius and the kinematics of each nuclear disk, yielding dynamical masses consistent with the masses and sizes derived from the dust emission. In Arp 220, the major dust and gas concentrations are at radii less than 50 pc in both counter-rotating nuclear disks. The thickness of the disks in Arp 220 estimated from the velocity dispersion and rotation velocities are 10-20 pc and the mean gas densities are nH_2 ˜ 10^5 cm-3 at R <50 pc. We develop an analytic treatment for the molecular excitation (including photon trapping), yielding volume densities for both the HCN and CS emission with n H2 ~ 2 × 105 cm-3. The agreement of the mean density from the total mass and size with that required for excitation suggests that the volume is essentially filled with dense gas, i.e., it is not cloudy or like swiss cheese.

  19. Impact Of Sodium Oxalate, Sodium Aluminosilicate, and Gibbsite/Boehmite on ARP Filter Performance

    SciTech Connect

    Poirier, M.; Burket, P.

    2015-11-01

    The Savannah River Site (SRS) is currently treating radioactive liquid waste with the Actinide Removal Process (ARP) and the Modular Caustic Side Solvent Extraction Unit (MCU). Recently, the low filter flux through the ARP of approximately 5 gallons per minute has limited the rate at which radioactive liquid waste can be treated. Salt Batch 6 had a lower processing rate and required frequent filter cleaning. Savannah River Remediation (SRR) has a desire to understand the causes of the low filter flux and to increase ARP/MCU throughput. SRR requested SRNL to conduct bench-scale filter tests to evaluate whether sodium oxalate, sodium aluminosilicate, or aluminum solids (i.e., gibbsite and boehmite) could be the cause of excessive fouling of the crossflow or secondary filter at ARP. The authors conducted the tests by preparing slurries containing 6.6 M sodium Salt Batch 6 supernate, 2.5 g MST/L slurry, and varying concentrations of sodium oxalate, sodium aluminosilicate, and aluminum solids, processing the slurry through a bench-scale filter unit that contains a crossflow primary filter and a dead-end secondary filter, and measuring filter flux and transmembrane pressure as a function of time. Among the conclusions drwn from this work are the following: (1) All of the tests showed some evidence of fouling the secondary filter. This fouling could be from fine particles passing through the crossflow filter. (2) The sodium oxalate-containing feeds behaved differently from the sodium aluminosilicate- and gibbsite/boehmite-containing feeds.

  20. Crucial roles of the Arp2/3 complex during mammalian corticogenesis.

    PubMed

    Wang, Pei-Shan; Chou, Fu-Sheng; Ramachandran, Sreekumar; Xia, Sheng; Chen, Huei-Ying; Guo, Fengli; Suraneni, Praveen; Maher, Brady J; Li, Rong

    2016-08-01

    The polarity and organization of radial glial cells (RGCs), which serve as both stem cells and scaffolds for neuronal migration, are crucial for cortical development. However, the cytoskeletal mechanisms that drive radial glial outgrowth and maintain RGC polarity remain poorly understood. Here, we show that the Arp2/3 complex - the unique actin nucleator that produces branched actin networks - plays essential roles in RGC polarity and morphogenesis. Disruption of the Arp2/3 complex in murine RGCs retards process outgrowth toward the basal surface and impairs apical polarity and adherens junctions. Whereas the former is correlated with an abnormal actin-based leading edge, the latter is consistent with blockage in membrane trafficking. These defects result in altered cell fate, disrupted cortical lamination and abnormal angiogenesis. In addition, we present evidence that the Arp2/3 complex is a cell-autonomous regulator of neuronal migration. Our data suggest that Arp2/3-mediated actin assembly might be particularly important for neuronal cell motility in a soft or poorly adhesive matrix environment. PMID:27385014

  1. Genetically encoded photoswitching of actin assembly through the Cdc42-WASP-Arp2/3 complex pathway

    PubMed Central

    Leung, Daisy W.; Otomo, Chinatsu; Chory, Joanne; Rosen, Michael K.

    2008-01-01

    General methods to engineer genetically encoded, reversible, light-mediated control over protein function would be useful in many areas of biomedical research and technology. We describe a system that yields such photo-control over actin assembly. We fused the Rho family GTPase Cdc42 in its GDP-bound form to the photosensory domain of phytochrome B (PhyB) and fused the Cdc42 effector, the Wiskott-Aldrich Syndrome Protein (WASP), to the light-dependent PhyB-binding domain of phytochrome interacting factor 3 (Pif3). Upon red light illumination, the fusion proteins bind each other, activating WASP, and consequently stimulating actin assembly by the WASP target, the Arp2/3 complex. Binding and WASP activation are reversed by far-red illumination. Our approach, in which the biochemical specificity of the nucleotide switch in Cdc42 is overridden by the light-dependent PhyB-Pif3 interaction, should be generally applicable to other GTPase-effector pairs. PMID:18728185

  2. Involvement of the Rac1-IRSp53-Wave2-Arp2/3 Signaling Pathway in HIV-1 Gag Particle Release in CD4 T Cells

    PubMed Central

    Thomas, Audrey; Mariani-Floderer, Charlotte; López-Huertas, Maria Rosa; Gros, Nathalie; Hamard-Péron, Elise; Favard, Cyril; Ohlmann, Theophile; Alcamí, José

    2015-01-01

    ABSTRACT During HIV-1 assembly, the Gag viral proteins are targeted and assemble at the inner leaflet of the cell plasma membrane. This process could modulate the cortical actin cytoskeleton, located underneath the plasma membrane, since actin dynamics are able to promote localized membrane reorganization. In addition, activated small Rho GTPases are known for regulating actin dynamics and membrane remodeling. Therefore, the modulation of such Rho GTPase activity and of F-actin by the Gag protein during virus particle formation was considered. Here, we studied the implication of the main Rac1, Cdc42, and RhoA small GTPases, and some of their effectors, in this process. The effect of small interfering RNA (siRNA)-mediated Rho GTPases and silencing of their effectors on Gag localization, Gag membrane attachment, and virus-like particle production was analyzed by immunofluorescence coupled to confocal microscopy, membrane flotation assays, and immunoblot assays, respectively. In parallel, the effect of Gag expression on the Rac1 activation level was monitored by G-LISA, and the intracellular F-actin content in T cells was monitored by flow cytometry and fluorescence microscopy. Our results revealed the involvement of activated Rac1 and of the IRSp53-Wave2-Arp2/3 signaling pathway in HIV-1 Gag membrane localization and particle release in T cells as well as a role for actin branching and polymerization, and this was solely dependent on the Gag viral protein. In conclusion, our results highlight a new role for the Rac1-IRSp53-Wave2-Arp2/3 signaling pathway in the late steps of HIV-1 replication in CD4 T lymphocytes. IMPORTANCE During HIV-1 assembly, the Gag proteins are targeted and assembled at the inner leaflet of the host cell plasma membrane. Gag interacts with specific membrane phospholipids that can also modulate the regulation of cortical actin cytoskeleton dynamics. Actin dynamics can promote localized membrane reorganization and thus can be involved in

  3. ARPES investigation of Fe-based superconductor KFe2As2 and related compounds

    NASA Astrophysics Data System (ADS)

    Richard, Pierre; Shi, X.; Lv, B.-Q.; Zhang, P.; Qian, T.; Ding, H.; Kim, T. K.; Hoesch, M.; Fang, D.-L.; Wen, H.-H.; Chen, X.-H.; van Roekeghem, A.; Seth, P.; Biermann, S.

    KFe2As2 is the end-member of the Ba1-xKxFe2As2 family of Fe-based superconductors. Despite a small Tc of 3 K, this compound is of particular interest because unlike the other members of this family of superconductors, the Fermi surface of KFe2As2 is free of electron pocket. Interest for this material was intensified following various reports on possible nodal superconducting order parameters in this system. Due to its momentum-resolved capabilities, angle-resolved photoemission spectroscopy (ARPES) is particularly suitable for investigating the key aspects of the electronic structure of materials. In this work we present recent ARPES data of KFe2As2 and related materials.

  4. Reconciling STS and ARPES data for the correlated superconductor LiFeAs

    NASA Astrophysics Data System (ADS)

    Hong, Jongbae; Abergel, David

    The inconsistency between the density of states revealed by scanning tunneling spectroscopy (STS) and that given by angle-resolved photoemission spectroscopy (ARPES) is a substantial problem for understanding the nature of strongly correlated superconductors such as Fe-based LiFeAs and the cuprates. We reveal that the two side peaks commonly appearing in both pnictide and cuprate superconductors are the result of the non-equilibrium behavior associated with singlet cotunneling from the tip to the strongly correlated sample. We accurately reproduce the STS line shape of the Fe-based LiFeAs using a sample density of states which coincides with ARPES data, thereby producing a unified description for these materials.

  5. A test of the massive binary black hole hypothesis - Arp 102B

    NASA Technical Reports Server (NTRS)

    Helpern, J. P.; Filippenko, Alexei V.

    1988-01-01

    The emission-line spectra of several AGN have broad peaks which are significantly displaced in velocity with respect to the host galaxy. An interpretation of this effect in terms of orbital motion of a binary black hole predicts periods of a few centuries. It is pointed out here that recent measurements of the masses and sizes of many low-luminosity AGN imply orbital periods much shorter than this. In particular, it is found that the elliptical galaxy Arp 102B is the most likely candidate for observation of radial velocity variations; its period is expected to be about 3 yr. The H-alpha line profile of Arp 102B has been measured for 5 yr without detecting any change in velocity, and it is thus found that a rather restrictive observational test of the massive binary black hole hypothesis already exists, albeit for this one object.

  6. Commissioning of a new beamline and station for ARPES at NSRL

    NASA Astrophysics Data System (ADS)

    Zou, Chongwen; Sun, Bai; Zhang, Wenhua; Wang, Guodong; Xu, Pengshou; Wang, Qiuping; Xu, Faqiang; Pan, Haibin

    2005-08-01

    The commissioning of a new beamline and station for angle-resolved photoelectron spectroscopy (ARPES) at the National Synchrotron Radiation Laboratory (NSRL) in Hefei is described. The beamline employs a variable angle spherical grating monochromator (VASGM) covering the photon energy from about 10 to 300 eV. The resolution and the flux of the beamline have been measured using a gas cell and a calibrated photodiode. The whole range resolving power is better than 1000 and the flux is better than 4×10 10photons/s/100 mA which have reached the specification of original design. By using the method of second harmonic spectra for high energy and the valence band spectra for low energy, the whole range incident photon energies have been calibrated. Finally, an ARPES experiment from a standard Cu sample is taken to illustrate the performance of the whole system.

  7. The evolutionary history of the interacting Galaxy system NGC 7714/7715 (Arp 284)

    NASA Technical Reports Server (NTRS)

    Smith, Beverly J.; Wallin, John F.

    1992-01-01

    The distribution and kinematics of atomic hydrogen in an interacting galaxy pair are studied to develop a model of its formation and assess its implications. H I gas peaks, bridges, and tails for NGC 7714/7715 (Arp 284) are identified with the VLA observations, and the velocity field appears to indicate that of an inclined rotating disk. A parabolic off-center collision is modeled for two disk galaxies with different masses, and formation scenario leads to results consistent with the observations. The point of closest approach occurred 1.1 x 10 exp 8 years ago, and the inclination angle for NGC 7714 is given at around 30 deg. This ring galaxy's lack of star formation is attributed to the large impact parameter associated with the parabolic off-center collision considered for Arp 284. Star formation and the initial mass function of the interacting galaxy pair are studied to assess the age and composition of the objects.

  8. Structure of line-emitting accretion disks in active galactic nuclei - Arp 102B

    NASA Technical Reports Server (NTRS)

    Chen, Kaiyou; Halpern, Jules P.

    1989-01-01

    The prime objects of the present self-consistent model of a line-emitting accretion disk able to account for the properties observed in a small class of AGNs are Arp 102B and 3C 390.3, whose double-peaked emission lines have been attributed to a Keplerian disk. Improved calculations of the line profile of a relativistic Keplerian disk, generalized to include a variety of emissivity laws as well as local broadening due to electron scattering or turbulence, are noted to fit Arp 102B; analytic and numerical calculations of the solid angle presented by the outer thin disk to an extended isotropic source of illumination demonstrate that the energy budget requirements for line emission from the disk are also satisfied.

  9. Arp2/3-mediated actin-based motility: a tail of pathogen abuse

    PubMed Central

    Welch, Matthew D.; Way, Michael

    2014-01-01

    Intracellular pathogens have developed elaborate mechanisms to exploit the different cellular systems of their unwilling hosts to facilitate their entry, replication and survival. In particular, a diverse range of bacteria and viruses have evolved unique strategies to harness the power of Arp2/3-mediated actin polymerization to enhance their cell-to-cell spread. In this review, we discuss how studying these pathogens has revolutionized our molecular understanding of Arp2/3-dependent actin assembly, and revealed key signalling pathways regulating actin assembly in cells. Further studies with known and newly emerging pathogens will undoubtedly continue to enhance our understanding of the role of the actin cytoskeleton during pathogenesis. Moreover, looking back over the last 20 years, it would be surprising if future analyses of microbe-host interactions did not continue to uncover new mechanisms regulating actin assembly and dynamics, as well as unexpected cellular functions for actin. PMID:24034611

  10. OSSE observations of the ultraluminous infrared galaxies ARP 220 and MRK 273

    NASA Technical Reports Server (NTRS)

    Dermer, C. D.; Shier, L. M.; Sturner, S. J.; McNaron-Brown, K.; Bland-Hawthorn, J.

    1997-01-01

    The results of oriented scintillation spectrometer experiment (OSSE) observations of the ultraluminous infrared galaxies Arp 220 and Mrk 273 are reported. The pointings of Arp 220 and Mrk 273 concentrated on their upper limits. The gamma ray luminosities from these sources were found to be between one and two orders of magnitude smaller than the infrared luminosities. Multiwavelength luminosity spectra are produced from the radio to the gamma ray regime, and are compared with the typical multiwavelength spectra of active galactic nuclei. The lack of measured gamma ray emission provides no evidence for the existence of buried active galactic nuclei in these ultraluminous infrared galaxies, but is consistent with an origin of the infrared luminosity from starburst activity.

  11. The Isolated Interacting Galaxy Pair NGC 5426/27 (Arp 271)

    NASA Astrophysics Data System (ADS)

    Fuentes-Carrera, I.; Rosado, M.; Amram, P.; Dultzin-Hacyan, D.; Bernal, A.; Salo, H.; Laurikainen, E.; Cruz-González, I.; Le Coarer, E.

    2001-03-01

    The isolated interacting galaxy pair NGC 5426/27 (Arp 271) was observed using the scanning Fabry-Perot interferometer PUMA. The velocity field, various kinematical parameters and rotation curve for each galaxy were derived. We found a small bar-like structure in NGC 5426 and a severely distorted velocity field for NGC 5427. A range of possible masses was computed for each galaxy.

  12. Enhanced Positioning Algorithm of ARPS for Improving Accuracy and Expanding Service Coverage.

    PubMed

    Lee, Kyuman; Baek, Hoki; Lim, Jaesung

    2016-01-01

    The airborne relay-based positioning system (ARPS), which employs the relaying of navigation signals, was proposed as an alternative positioning system. However, the ARPS has limitations, such as relatively large vertical error and service restrictions, because firstly, the user position is estimated based on airborne relays that are located in one direction, and secondly, the positioning is processed using only relayed navigation signals. In this paper, we propose an enhanced positioning algorithm to improve the performance of the ARPS. The main idea of the enhanced algorithm is the adaptable use of either virtual or direct measurements of reference stations in the calculation process based on the structural features of the ARPS. Unlike the existing two-step algorithm for airborne relay and user positioning, the enhanced algorithm is divided into two cases based on whether the required number of navigation signals for user positioning is met. In the first case, where the number of signals is greater than four, the user first estimates the positions of the airborne relays and its own initial position. Then, the user position is re-estimated by integrating a virtual measurement of a reference station that is calculated using the initial estimated user position and known reference positions. To prevent performance degradation, the re-estimation is performed after determining its requirement through comparing the expected position errors. If the navigation signals are insufficient, such as when the user is outside of airborne relay coverage, the user position is estimated by additionally using direct signal measurements of the reference stations in place of absent relayed signals. The simulation results demonstrate that a higher accuracy level can be achieved because the user position is estimated based on the measurements of airborne relays and a ground station. Furthermore, the service coverage is expanded by using direct measurements of reference stations for user

  13. A deep Chandra observation of the interacting star-forming galaxy Arp 299

    NASA Astrophysics Data System (ADS)

    Anastasopoulou, K.; Zezas, A.; Ballo, L.; Della Ceca, R.

    2016-08-01

    We present results from a 90 ks Chandra ACIS-S observation of the X-ray luminous interacting galaxy system Arp 299 (NGC 3690/IC 694). We detect 25 discrete X-ray sources with luminosities above ˜4.0 × 1038 erg s-1 covering the entire Ultra Luminous X-ray source (ULX) regime. Based on the hard X-ray spectra of the non-nuclear discrete sources identified in Arp 299, and their association with young, actively star-forming region of Arp 299 we identify them as HMXBs. We find in total 20 off-nuclear sources with luminosities above the ULX limit, 14 of which are point-like sources. Furthermore we observe a marginally significant deficit in the number of ULXs, with respect to the number expected from scaling relations of X-ray binaries with the star formation rate (SFR). Although the high metallicity of the galaxy could result in lower ULX numbers, the good agreement between the observed total X-ray luminosity of ULXs, and that expected from the relevant scaling relation indicates that this deficit could be the result of confusion effects. The integrated spectrum of the galaxy shows the presence of a hot gaseous component with kT = 0.72 ± 0.03 keV, contributing ˜20 per cent of the soft (0.1-2.0 keV) unabsorbed luminosity of the galaxy. A plume of soft X-ray emission in the west of the galaxy indicates a large scale outflow. We find that the AGN in NGC 3690 contributes only 22 per cent of the observed broad-band X-ray luminosity of Arp 299.

  14. Kinematics and excitation of the nuclear spiral in the active galaxy Arp 102B

    NASA Astrophysics Data System (ADS)

    Couto, G. S.; Storchi-Bergmann, T.; Axon, D. J.; Robinson, A.; Kharb, P.; Riffel, R. A.

    2014-10-01

    We present a two-dimensional analysis of the gaseous excitation and kinematics of the inner 2.5 × 1.7 kpc^{2} of the LINER/Seyfert 1 galaxy Arp 102B, from optical spectra obtained with the GMOS integral field spectrograph on the Gemini North telescope at a spatial resolution of ≍ 250 pc. Emission-line flux maps show the same two-armed nuclear spiral we have discovered in previous observations with the HST-ACS camera. One arm reaches 1 kpc to the east and the other 500 pc to the west, with a 8.4 GHz VLA bent radio jet correlating with the former. Gas excitation along the arms is low, with line ratios typical of LINERs. The gas density is highest at the nucleus and in the northern border of the east arm, at a region where the radio jet seems to be deflected. Centroid velocity maps suggest that most gas is in rotation in an inclined disk with line of nodes along position angle ≍ 88°, redshifts to the west and blueshifts to the east, with lower blueshifts correlated with the eastern arm and radio jet. This correlation suggests that the jet is interacting with gas in the disk. Channel maps show blueshifts but also some redshifts at the eastern arm and jet location which can be interpreted as originated in the front and back walls of an outflow pushed by the radio jet, suggesting also that the outflow is launched close to the plane of the sky. We propose a scenario in which gas has been recently captured by Arp 102B in an interaction with Arp 102A, settling in a disk rotating around the nucleus of Arp 102B and triggering its nuclear activity. A nuclear jet is pushing the circumnuclear gas, giving origin to the nuclear arms.

  15. Sludge Batch 4 Simulant Flowsheet Studies with ARP and MCU: Impact of MCU Organics

    SciTech Connect

    Baich, M. A.; Herman, C. C.; Eibling, R. E.; Williams, M. F.; Smith, F. G.

    2005-07-01

    Two facilities for treating the salt currently being stored in the High Level Waste (HLW) tanks are currently planned to begin operations during the processing of Sludge Batch 4 (SB4). The Immobilization Technology Section (ITS) of the Savannah River National Laboratory (SRNL) was requested by the Defense Waste Processing Facility (DWPF) via Technical Task Request (TTR) HLW/DWPF/TTR-2004-0031 (Washburn, 2004) to evaluate the impacts on DWPF processing for streams from the Actinide Removal Process (ARP) and the Modular Caustic Side Solvent Side Extraction (CSSX) Unit (MCU). In particular, the TTR requests SRNL to validate the existing process flowsheet and establish a coupled operations flowsheet for use with SB4. The flowsheet runs are required so an evaluation of potential chemical processing issues, quantification of the potential hydrogen generation rates, and estimation of the required acid stoichiometry can be made. Previous testing (Baich et. al., 2003) was performed for incorporating ARP/MST in Sludge Batch 3 (SB3) and recommendations were made to DWPF on possible flowsheet options. However, since that time, some changes have occurred to the ARP facility processing strategy, and material balances have been revised (Subosits, 2004). Thus, testing with updated compositions was necessary. Since the MCU is a new design and project, no CPC flowsheet studies have been performed for this stream. This testing will validate the previously recommended ARP stream addition methods based on the new information and based on the need to also incorporate the MCU stream. The basic principle of solvent extraction is to use a sparingly soluble diluent material that carries an extractant that will complex with the cesium ions in the caustic HLW solution. The decontaminated aqueous stream (raffinate) is then sent to Saltstone for disposal. The cesium contained in the organic phase (solvent) can then be stripped into an aqueous phase ready for transfer to the DWPF. The solvent is

  16. A deep Chandra observation of the interacting star-forming galaxy Arp 299

    NASA Astrophysics Data System (ADS)

    Anastasopoulou, K.; Zezas, A.; Ballo, L.; Della Ceca, R.

    2016-05-01

    We present results from a 90 ks Chandra ACIS-S observation of the X-ray luminous interacting galaxy system Arp 299 (NGC 3690/IC 694). We detect 25 discrete X-ray sources with luminosities above ˜4.0 × 1038 erg s-1 covering the entire Ultra Luminous X-ray source (ULX) regime. Based on the hard X-ray spectra of the non-nuclear discrete sources identified in Arp 299, and their association with young, actively star-forming region of Arp 299 we identify them as HMXBs. We find in total 20 off-nuclear sources with luminosities above the ULX limit, 14 of which are point-like sources. Furthermore we observe a marginally significant deficit in the number of ULXs, with respect to the number expected from scaling relations of X-ray binaries with the star formation rate (SFR). Although the high metalicity of the galaxy could result in lower ULX numbers, the good agreement between the observed total X-ray luminosity of ULXs, and that expected from the relevant scaling relation indicates that this deficit could be the result of confusion effects. The integrated spectrum of the galaxy shows the presence of a hot gaseous component with kT = 0.72 ± 0.03 keV, contributing ˜20% of the soft (0.1-2.0 keV) unabsorbed luminosity of the galaxy. A plume of soft X-ray emission in the west of the galaxy indicates a large scale outflow. We find that the AGN in NGC 3690 contributes only 22% of the observed broad-band X-ray luminosity of Arp 299.

  17. VizieR Online Data Catalog: Arp 220 HCN and HCO+ data cubes (Martin+,

    NASA Astrophysics Data System (ADS)

    Martin, S.; Aalto, S.; Sakamoto, K.; Gonzalez-Alfonso, E.; Muller, S.; Henkel, C.; Garcia-Burillo, S.; Aladro, R.; Costagliola, F.; Harada, N.; Krips, M.; Martin-Pintado, J.; Muhle, S.; van der Werf, P.; Viti, S.

    2016-03-01

    The observations were carried out with ALMA in its Cycle 1 as part of a spectral line survey of Arp 220 (Martin et al., in preparation). In this paper we report the measurements covering HCN and HCO+ in their J=3-2 (261.152GHz and 262.794GHz) and J=4-3 (348.194GHz and 350.383GHz) transitions, as well as the corresponding v2=1 transitions of HCN. (2 data files).

  18. ALMA IMAGING OF HCN, CS, AND DUST IN ARP 220 AND NGC 6240

    SciTech Connect

    Scoville, Nick; Manohar, Swarnima; Murchikova, Lena; Sheth, Kartik; Walter, Fabian; Zschaechner, Laura; Yun, Min; Koda, Jin; Sanders, David; Barnes, Joshua; Thompson, Todd; Robertson, Brant; Tacconi, Linda; Narayanan, Desika; Genzel, Reinhard; Davies, Richard; Hernquist, Lars; Brown, Robert; Hayward, Christopher C.; Kartaltepe, Jeyhan; and others

    2015-02-10

    We report ALMA Band 7 (350 GHz) imaging at 0.''4-0.''6 resolution and Band 9 (696 GHz) at ∼0.''25 resolution of the luminous IR galaxies Arp 220 and NGC 6240. The long wavelength dust continuum is used to estimate interstellar medium masses for Arp 220 east and west and NGC 6240 of 1.9, 4.2, and 1.6 × 10{sup 9} M {sub ☉}within radii of 69, 65, and 190 pc. The HCN emission was modeled to derive the emissivity distribution as a function of radius and the kinematics of each nuclear disk, yielding dynamical masses consistent with the masses and sizes derived from the dust emission. In Arp 220, the major dust and gas concentrations are at radii less than 50 pc in both counter-rotating nuclear disks. The thickness of the disks in Arp 220 estimated from the velocity dispersion and rotation velocities are 10-20 pc and the mean gas densities are n{sub H{sub 2}}∼10{sup 5} cm{sup –3} at R <50 pc. We develop an analytic treatment for the molecular excitation (including photon trapping), yielding volume densities for both the HCN and CS emission with n {sub H2} ∼ 2 × 10{sup 5} cm{sup –3}. The agreement of the mean density from the total mass and size with that required for excitation suggests that the volume is essentially filled with dense gas, i.e., it is not cloudy or like swiss cheese.

  19. Dynamic maintenance of asymmetric meiotic spindle position through Arp2/3 complex-driven cytoplasmic streaming in mouse oocytes

    PubMed Central

    Yi, Kexi; Unruh, Jay R.; Deng, Manqi; Slaughter, Brian D.; Rubinstein, Boris; Li, Rong

    2012-01-01

    Mature mammalian oocytes are poised for the completion of second polar body extrusion upon fertilization by positioning the metaphase spindle in close proximity to an actomyosin-rich cortical cap. Loss of this spindle position asymmetry is often associated with poor oocyte quality and infertility 1–3. Here, we report a novel role for the Arp2/3 actin nucleation complex in the maintenance of asymmetric spindle position in mature mouse oocytes. The Arp2/3 complex localizes to the cortical cap in a Ran GTPase-dependent manner and accounts for the nucleation of the majority of actin filaments in both the cortical cap and a cytoplasmic actin network. Inhibition of Arp2/3 complex activity or localization leads to rapid dissociation of the spindle from the cortex. High resolution live imaging and spatiotemporal image correlation spectroscopy (STICS) analysis reveal that in normal oocytes actin filaments flow continuously away from the Arp2/3-rich cortex, generating a cytoplamic streaming that results in a net pushing force on the spindle toward the actomyosin cap. Arp2/3 inhibition not only diminishes this actin flow and cytoplamic streaming but also enables a reverse streaming driven by myosin-II-based cortical contraction, leading to spindle movement away from the cortex. We conclude that the Arp2/3 complex maintains asymmetric meiotic spindle position by generating an actin polymerization-driven cytoplamic streaming and by suppressing a counteracting force from myosin-II-based contractility. PMID:21874009

  20. Profilin-1 serves as a gatekeeper for actin assembly by Arp2/3-dependent and –independent pathways

    PubMed Central

    Rotty, Jeremy D.; Wu, Congying; Haynes, Elizabeth M.; Suarez, Cristian; Winkelman, Jonathan D.; Johnson, Heath E.; Haugh, Jason M.; Kovar, David R.; Bear, James E.

    2015-01-01

    SUMMARY Cells contain multiple F-actin assembly pathways including the Arp2/3 complex, formins, and Ena/VASP, which have largely been analyzed separately. They collectively generate the bulk of F-actin from a common pool of G-actin; however, the interplay/competition between these pathways remains poorly understood. Using fibroblast lines derived from an Arpc2 conditional knockout mouse, we established matched-pair cells with and without the Arp2/3 complex. Arpc2−/− cells lack lamellipodia and migrate slower than WT cells, but have F-actin levels indistinguishable from controls. Actin assembly in Arpc2−/− cells was resistant to cytochalasin-D and was highly dependent on profilin-1 and Ena/VASP, but not formins. Profilin-1 depletion in WT cells increased F-actin and Arp2/3 complex in lamellipodia. Conversely, addition of exogenous profilin-1 inhibited Arp2/3 complex actin nucleation in vitro and in vivo. These observations suggest that antagonism of the Arp2/3 complex by profilin-1 in cells maintains actin homeostasis by balancing Arp2/3 complex-dependent and independent actin assembly pathways. PMID:25543281

  1. Supplementation of procyanidins B2 attenuates photooxidation-induced apoptosis in ARPE-19 cells.

    PubMed

    Li, Weinan; Jiang, Yun; Sun, Tao; Yao, Xiaomin; Sun, Xiangjun

    2016-09-01

    During the aging process, dimers of dietary vitamin A accumulated in retinal pigment epithelium (RPE) cells. Vitamin A dimer-mediated photooxidation resulted in RPE apoptosis, which is associated with age-related degenerative disease of retina, leading to blindness. It has been reported that proanthocyanidin-rich grape seed extract reduces oxidative stress in the eye. In this study, we investigated the underlying mechanism of photooxidation-induced apoptosis inhibition by procyanidins B2 (PB2), one of the main components of grape seed proanthocyanidin. To mimic vitamin A dimer-mediated photooxidation, ARPE-19 cells that accumulated vitamin A dimer, A2E, were used as a model system. Exposure of A2E loaded ARPE-19 cells to blue light induced ER stress and resulted in significant apoptosis. Pretreatment of blue light-exposed A2E containing ARPE-19 cells with PB2 inhibited apoptosis, increased the ratio of Bcl-2/Bax in the mitochondria, attenuated ROS and cytochrome c release, and decreased caspase cleavage. Additionally, PB2 inhibited the phosphorylation of ER stress markers elF2α and IRE1α and reduced CHOP expression. Moreover, PB2 inhibition of apoptosis is dependent on the UPR chaperone GRP78, indicating PB2 inhibits vitamin A dimer-mediated apoptosis in RPE cells by activating the UPR. PMID:27251367

  2. CANDIDATE TIDAL DWARF GALAXIES IN Arp 305: LESSONS ON DWARF DETACHMENT AND GLOBULAR CLUSTER FORMATION

    SciTech Connect

    Hancock, Mark; Smith, Beverly J.; Giroux, Mark L.; Hurlock, Sabrina; Struck, Curtis E-mail: smithbj@etsu.edu E-mail: zshh7@goldmail.etsu.edu

    2009-06-15

    To search for Tidal Dwarf Galaxies (TDGs) and to study star formation (SF) in tidal features, we are conducting a large UV imaging survey of interacting galaxies selected from the Arp (1996) Atlas using the Galaxy Evolution Explorer (GALEX) telescope. As part of that study, we present a GALEX UV and Sloan Digital Sky Survey and SARA optical study of the gas-rich interacting galaxy pair Arp 305 (NGC 4016/7). The GALEX UV data reveal much extended diffuse UV emission and SF outside the disks. This includes a luminous star-forming region between the two galaxies, and a number of such regions in tidal tails. We have identified 45 young star-forming clumps in Arp 305, including several TDG candidates. By comparing the UV and optical colors to population synthesis models, we determined that the clumps are very young, with several having ages {approx}6 Myr. We do not find many intermediate age clumps in spite of the fact that the last closest encounter was about 300 Myr ago. We have used a smooth particle hydrodynamics code to model the interaction and determine the fate of the star clusters and candidate TDGs.

  3. A mechanism of leading-edge protrusion in the absence of Arp2/3 complex

    PubMed Central

    Suraneni, Praveen; Fogelson, Ben; Rubinstein, Boris; Noguera, Philippe; Volkmann, Niels; Hanein, Dorit; Mogilner, Alex; Li, Rong

    2015-01-01

    Cells employ protrusive leading edges to navigate and promote their migration in diverse physiological environments. Classical models of leading-edge protrusion rely on a treadmilling dendritic actin network that undergoes continuous assembly nucleated by the Arp2/3 complex, forming ruffling lamellipodia. Recent work demonstrated, however, that, in the absence of the Arp2/3 complex, fibroblast cells adopt a leading edge with filopodia-like protrusions (FLPs) and maintain an ability to move, albeit with altered responses to different environmental signals. We show that formin-family actin nucleators are required for the extension of FLPs but are insufficient to produce a continuous leading edge in fibroblasts lacking Arp2/3 complex. Myosin II is concentrated in arc-like regions of the leading edge in between FLPs, and its activity is required for coordinated advancement of these regions with formin-generated FLPs. We propose that actomyosin contraction acting against membrane tension advances the web of arcs between FLPs. Predictions of this model are verified experimentally. The dependence of myosin II in leading-edge advancement helps explain the previously reported defect in directional movement in the Arpc3-null fibroblasts. We provide further evidence that this defect is cell autonomous during chemotaxis. PMID:25568333

  4. The Quasiparticle Puzzle: Reconciling ARPES and FTSTS Studies of Bi2212

    SciTech Connect

    Vishik, I.M.; Nowadnick, E.A.; Lee, W.S.; Shen, Z.X.; Moritz, B.; Devereaux, T.P.; Tanaka, K.; Sasagawa, T.; Fujii, T.; /Tokyo U.

    2009-12-17

    Angle Resolved Photoemission Spectroscopy (ARPES) probes the momentum-space electronic structure of materials, and provides invaluable information about the high-temperature superconducting cuprates. Likewise, cuprates real-space, inhomogeneous electronic structure is elucidated by Scanning Tunneling Spectroscopy (STS). Recently, STS has exploited quasiparticle interference (QPI) - wave-like electrons scattering off impurities to produce periodic interference patterns - to infer properties of the QP in momentum-space. Surprisingly, some interference peaks in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} (Bi-2212) are absent beyond the antiferromagnetic (AF) zone boundary, implying the dominance of particular scattering process. Here, we show that ARPES sees no evidence of quasiparticle (QP) extinction: QP-like peaks are measured everywhere on the Fermi surface, evolving smoothly across the AF zone boundary. This apparent contradiction stems from different natures of single-particle (ARPES) and two-particle (STS) processes underlying these probes. Using a simple model, we demonstrate extinction of QPI without implying the loss of QP beyond the AF zone boundary.

  5. Compact OH megamaser and probable quasar activity in the galaxy Arp 220

    NASA Astrophysics Data System (ADS)

    Lonsdale, Colin J.; Diamond, Philip J.; Smith, Harding E.; Lonsdale, Carol J.

    1994-07-01

    ARP 220 is the prototype far-infrared ultraluminous galaxy, and the origin of its luminosity-a burst of massive star formation or a quasar obscured by a layer of dense gas and dust-has been the subject of much debate1,2. It also contains the prototypical OH megamaser3-an extremely luminous version of masers (microwave lasers) commonly found in our own galaxy. It has been thought that the dense gas in the inner few hundred parsecs of megamaser galaxies acts as a low-gain masing screen, pumped by the far-infrared radiation, which amplifies background continuum emission from the nuclear regions4-6. Here we show, using new very-long-baseline interferometry observations, that the OH line peak in Arp 220 originates in a structure <=1 pc across, position-ally aligned with a weak continuum feature, and that most of the emission originates on scales of <= 10 pc. These results imply that the maser is physically 10-100 times smaller than previously thought5,6, strongly suggesting that much of the far-infrared radia-tion from Arp 220 arises in a very small region, possibly a dense molecular torus, surrounding a quasar nucleus.

  6. ARPES studies of the electronic structure of Fe-based superconductors

    NASA Astrophysics Data System (ADS)

    Lu, Donghui

    2009-03-01

    The recent discovery of superconductivity in Fe-based layered compounds has created renewed interest in high temperature superconductivity. With a superconducting transition temperature as high as 55 K, this discovery provides a new direction to understand the essential ingredients for achieving a high superconducting transition temperature. In this talk, I will present our recent angle-resolved photoemission spectroscopy (ARPES) studies on LaOFeP and (Ba,K)Fe2As2 systems, with special emphasis on the basic electronic structure of the parent compounds. For LaOFeP, quantitative agreement can be found between our ARPES data and the LDA band structure calculations, suggesting that a weak coupling approach based on an itinerant ground state may be more appropriate for understanding this new superconducting compound [1]. On the other hand, the picture for (Ba,K)Fe2As2 system is more complicated. I will discuss two important issues in these FeAs compounds: 1) the unexpected Fermi surface topology in both undoped and doped compounds; 2) the peculiar signature of the SDW transition in ARPES spectra for the parent compound. [4pt] [1] D. H. Lu, M. Yi, S.-K. Mo, A. S. Erickson, J. Analytis, J.-H. Chu, D. J. Singh, Z. Hussain, T. H. Geballe, I. R. Fisher & Z.-X. Shen, Nature 455, 81 (2008).

  7. α5β1 integrin recycling promotes Arp2/3-independent cancer cell invasion via the formin FHOD3.

    PubMed

    Paul, Nikki R; Allen, Jennifer L; Chapman, Anna; Morlan-Mairal, Maria; Zindy, Egor; Jacquemet, Guillaume; Fernandez del Ama, Laura; Ferizovic, Nermina; Green, David M; Howe, Jonathan D; Ehler, Elisabeth; Hurlstone, Adam; Caswell, Patrick T

    2015-09-14

    Invasive migration in 3D extracellular matrix (ECM) is crucial to cancer metastasis, yet little is known of the molecular mechanisms that drive reorganization of the cytoskeleton as cancer cells disseminate in vivo. 2D Rac-driven lamellipodial migration is well understood, but how these features apply to 3D migration is not clear. We find that lamellipodia-like protrusions and retrograde actin flow are indeed observed in cells moving in 3D ECM. However, Rab-coupling protein (RCP)-driven endocytic recycling of α5β1 integrin enhances invasive migration of cancer cells into fibronectin-rich 3D ECM, driven by RhoA and filopodial spike-based protrusions, not lamellipodia. Furthermore, we show that actin spike protrusions are Arp2/3-independent. Dynamic actin spike assembly in cells invading in vitro and in vivo is regulated by Formin homology-2 domain containing 3 (FHOD3), which is activated by RhoA/ROCK, establishing a novel mechanism through which the RCP-α5β1 pathway reprograms the actin cytoskeleton to promote invasive migration and local invasion in vivo. PMID:26370503

  8. α5β1 integrin recycling promotes Arp2/3-independent cancer cell invasion via the formin FHOD3

    PubMed Central

    Paul, Nikki R.; Allen, Jennifer L.; Chapman, Anna; Morlan-Mairal, Maria; Zindy, Egor; Jacquemet, Guillaume; Fernandez del Ama, Laura; Ferizovic, Nermina; Green, David M.; Howe, Jonathan D.; Ehler, Elisabeth; Hurlstone, Adam

    2015-01-01

    Invasive migration in 3D extracellular matrix (ECM) is crucial to cancer metastasis, yet little is known of the molecular mechanisms that drive reorganization of the cytoskeleton as cancer cells disseminate in vivo. 2D Rac-driven lamellipodial migration is well understood, but how these features apply to 3D migration is not clear. We find that lamellipodia-like protrusions and retrograde actin flow are indeed observed in cells moving in 3D ECM. However, Rab-coupling protein (RCP)-driven endocytic recycling of α5β1 integrin enhances invasive migration of cancer cells into fibronectin-rich 3D ECM, driven by RhoA and filopodial spike-based protrusions, not lamellipodia. Furthermore, we show that actin spike protrusions are Arp2/3-independent. Dynamic actin spike assembly in cells invading in vitro and in vivo is regulated by Formin homology-2 domain containing 3 (FHOD3), which is activated by RhoA/ROCK, establishing a novel mechanism through which the RCP–α5β1 pathway reprograms the actin cytoskeleton to promote invasive migration and local invasion in vivo. PMID:26370503

  9. Phosphorylation of CRN2 by CK2 regulates F-actin and Arp2/3 interaction and inhibits cell migration

    PubMed Central

    Xavier, Charles-Peter; Rastetter, Raphael H.; Blömacher, Margit; Stumpf, Maria; Himmel, Mirko; Morgan, Reginald O.; Fernandez, Maria-Pilar; Wang, Conan; Osman, Asiah; Miyata, Yoshihiko; Gjerset, Ruth A.; Eichinger, Ludwig; Hofmann, Andreas; Linder, Stefan; Noegel, Angelika A.; Clemen, Christoph S.

    2012-01-01

    CRN2 (synonyms: coronin 1C, coronin 3) functions in the re-organization of the actin network and is implicated in cellular processes like protrusion formation, secretion, migration and invasion. We demonstrate that CRN2 is a binding partner and substrate of protein kinase CK2, which phosphorylates CRN2 at S463 in its C-terminal coiled coil domain. Phosphomimetic S463D CRN2 loses the wild-type CRN2 ability to inhibit actin polymerization, to bundle F-actin, and to bind to the Arp2/3 complex. As a consequence, S463D mutant CRN2 changes the morphology of the F-actin network in the front of lamellipodia. Our data imply that CK2-dependent phosphorylation of CRN2 is involved in the modulation of the local morphology of complex actin structures and thereby inhibits cell migration. PMID:22355754

  10. EXTREME DUST DISKS IN Arp 220 AS REVEALED BY ALMA

    SciTech Connect

    Wilson, C. D.; Rangwala, N.; Glenn, J.; Maloney, P. R.; Spinoglio, L.; Pereira-Santaella, M.

    2014-07-10

    We present new images of Arp 220 from the Atacama Large Millimeter/submillimeter Array with the highest combination of frequency (691 GHz) and resolution (0.''36 × 0.''20) ever obtained for this prototypical ultraluminous infrared galaxy. The western nucleus is revealed to contain warm (200 K) dust that is optically thick (τ{sub 434} {sub μm} = 5.3), while the eastern nucleus is cooler (80 K) and somewhat less opaque (τ{sub 434} {sub μm} = 1.7). We derive full width at half-maximum diameters of 76 × ≤ 70 pc and 123 × 79 pc for the western and eastern nucleus, respectively. The two nuclei combined account for (83{sub −38}{sup +65} (calibration) {sub −34}{sup +0} (systematic))% of the total infrared luminosity of Arp 220. The luminosity surface density of the western nucleus (log (σT{sup 4})=14.3±0.2{sub −0.7}{sup +0} in units of L {sub ☉} kpc{sup –2}) appears sufficiently high to require the presence of an active galactic nucleus (AGN) or a ''hot starburst'', although the exact value depends sensitively on the brightness distribution adopted for the source. Although the role of any central AGN remains open, the inferred mean gas column densities of (0.6-1.8) × 10{sup 25} cm{sup –2} mean that any AGN in Arp 220 must be Compton-thick.

  11. Near-infrared (Fe II) and Pa Beta imaging and spectroscopy of Arp 220

    NASA Technical Reports Server (NTRS)

    Armus, L.; Shupe, D. L.; Matthews, K.; Soifer, B. T.; Neugebauer, G.

    1995-01-01

    We have imaged the ultraluminous infrared galaxy Arp 220 in light of the near-infrared (Fe II) 1.257 micron and Pa-beta lines, and have obtained spectra in the J- and H-band atmospheric windows. Arp 220 is a strong source of (Fe II) and Pa-beta emission, with luminosities of 1.3 x 10(exp 41) and 9.2 x 10(exp 40) ergs/s, respectively. The (Fe II) and Pa-beta emission are both extended over the central 2 sec-3 sec, but with different morphologies. We suggest that the extended (Fe II) emission is produced through the interaction of fast shocks with ambient gas in the interstellar medium (ISM) at the base of the outflowing, supernovae-driven superwind mapped by Heckman et al. (1987). The bolometric luminosity of the starburst required to power this wind is estimated to be at least 2 x 10(exp 11) solar luminosity. If the spatially unresolved (Fe II) emission is produced via a large number of supernova remnants, the implied rate is approximately 0.6/yr. The overall luminosity of such a starburst could account for a large fraction (1/2-1/3) of the Arp 220 energy budget, but the large deficit of ionizing photons (as counted by the Pa-beta luminosity) requires that the starburst be rapidly declining and/or have a low upper mass cutoff. Alternatively, dust may effectively compete with the gas for ionizing photons, or much of the ionizing radiation may escape through 'holes' in the ISM. It is also possible that a buried active galactic nuclei (AGN) produces a large fraction of the unresolved (Fe II) and Pa-beta emission. We briefly discuss these possibilities in light of these new imaging and spectroscopic data.

  12. A multi-frequency study of the peculiar interacting system Arp 206

    NASA Technical Reports Server (NTRS)

    Noreau, Louis; Kronberg, Philipp P.

    1990-01-01

    Arp 206 is a nearby, relatively large, and bright interacting system comprising unequal members: NGC 3432 and UGC 5983. A third anonymous galaxy, Arp 206c, is visible in the field. The CCD images show a well-developed bridge between NGC 3432 and UGC 5983. On the other hand, the complex H I tails are not visible in the optical. In the total H I map, the bridge is lost in a general envelope encompassing both galaxies. The bridge also appears to have some radio emission. On the Total H I map the system is rather edge-on, far more than it would appear in optical wavelengths. UGC 5983 falls exactly in line with NGC 3432. The velocity of the centers of mass of NGC 3432 and UGC 5983 are 530 km s(exp -1) and 630 km s(exp -1), respectively. In view of the considerable damage sustained by NGC 3432 and the apparent low mass of UGC 5983, it appears that the passage must have been at near parabolic speed, with a small pericentric distance and a very low inclination with rspect to the disk of NGC 3432. The apparent distribution of H I along the z axis of the galaxy could be accounted for by projection effects. The tidal appendage found at higher velocities, which rises at a P.A. approx. equal to 25 degrees west of the main body of the galaxy is probably the tail, the part of the tidal damage away from the perturbing companion. The bridge may be rising north-east from the galaxy and then continue under to the south of the galaxy. The relative sizes of the appendages would indicate that the pericenter was crossed recently. Any further inferences about the collision parameters will need to await the results of detailed computational modelling of the interaction. The authors also summarize the observational characteristics of NGC 3432, UGC 5983, and Arp 206c.

  13. ARPES studies on FeTe1-x Se x iron chalcogenides epitaxial thin films

    NASA Astrophysics Data System (ADS)

    Innocenti, Davide; Moreschini, Luca; Chang, Young Jun; Walter, Andrew; Bostwick, Aaron; di Castro, Daniele; Tebano, Antonello; Medaglia, Pier Gianni; Bellingeri, Emilio; Pallecchi, Ilaria; Ferdeghini, Carlo; Balestrino, Giuseppe; Rotenberg, Eli

    2011-03-01

    The physics of iron-based chalcogenides raises fundamental questions on the interplay of magnetic order and electron pairing at the origin of the superconducting state. We have performed angle-resolved photemission spectroscopy (ARPES) studies on high-quality epitaxial thin films of FeTe 1-x Se x , grown by in situ pulsed laser deposition (PLD) on beamline 7.0.1 at the ALS. Specifically, we are able to show the evolution of the band structure as a function of x. We discuss our experimental results in comparison to the available theoretical band calculations.

  14. Excited OH+, H2O+, and H3O+ in NGC 4418 and Arp 220

    NASA Astrophysics Data System (ADS)

    González-Alfonso, E.; Fischer, J.; Bruderer, S.; Müller, H. S. P.; Graciá-Carpio, J.; Sturm, E.; Lutz, D.; Poglitsch, A.; Feuchtgruber, H.; Veilleux, S.; Contursi, A.; Sternberg, A.; Hailey-Dunsheath, S.; Verma, A.; Christopher, N.; Davies, R.; Genzel, R.; Tacconi, L.

    2013-02-01

    We report on Herschel/PACS observations of absorption lines of OH+, H2O+ and H3O+ in NGC 4418 and Arp 220. Excited lines of OH+ and H2O+ with Elower of at least 285 and ~200 K, respectively, are detected in both sources, indicating radiative pumping and location in the high radiation density environment of the nuclear regions. Abundance ratios OH+/H2O+ of 1-2.5 are estimated in the nuclei of both sources. The inferred OH+ column and abundance relative to H nuclei are (0.5-1) × 1016 cm-2 and ~ 2 × 10-8, respectively. Additionally, in Arp 220, an extended low excitation component around the nuclear region is found to have OH+/H2O+ ~ 5-10. H3O+ is detected in both sources with N(H3O+) ~ (0.5-2) × 1016 cm-2, and in Arp 220 the pure inversion, metastable lines indicate a high rotational temperature of ~500 K, indicative of formation pumping and/or hot gas. Simple chemical models favor an ionization sequence dominated by H+ → O+ → OH+ → H2O+ → H3O+, and we also argue that the H+ production is most likely dominated by X-ray/cosmic ray ionization. The full set of observations and models leads us to propose that the molecular ions arise in a relatively low density (≳104 cm-3) interclump medium, in which case the ionization rate per H nucleus (including secondary ionizations) is ζ > 10-13 s-1, a lower limit that is several × 102 times the highest current rate estimates for Galactic regions. In Arp 220, our lower limit for ζ is compatible with estimates for the cosmic ray energy density inferred previously from the supernova rate and synchrotron radio emission, and also with the expected ionization rate produced by X-rays. In NGC 4418, we argue that X-ray ionization due to an active galactic nucleus is responsible for the molecular ion production. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  15. ARPES measurements of the superconducting gap of Fe-based superconductors and their implications to the pairing mechanism.

    PubMed

    Richard, P; Qian, T; Ding, H

    2015-07-29

    Its direct momentum sensitivity confers to angle-resolved photoemission spectroscopy (ARPES) a unique perspective in investigating the superconducting gap of multi-band systems. In this review we discuss ARPES studies on the superconducting gap of high-temperature Fe-based superconductors. We show that while Fermi-surface-driven pairing mechanisms fail to provide a universal scheme for the Fe-based superconductors, theoretical approaches based on short-range interactions lead to a more robust and universal description of superconductivity in these materials. Our findings are also discussed in the broader context of unconventional superconductivity. PMID:26153847

  16. Chandra Observations of Extended X-Ray Emission in ARP 220

    NASA Technical Reports Server (NTRS)

    McDowell, J. C.; Clements, D. L.; Lamb, S. A.; Shaked, S.; Hearn, N. C.; Colina, L.; Mundell, C.; Borne, K.; Baker, A. C.; Arribas, S.

    2003-01-01

    We resolve the extended X-ray emission from the prototypical ultraluminous infrared galaxy Arp 220. Extended, faint, edge-brightened, soft X-ray lobes outside the optical galaxy are observed to a distance of 1CL 15 kpc on each side of the nuclear region. Bright plumes inside the optical isophotes coincide with the optical line emission and extend 1 1 kpc from end to end across the nucleus. The data for the plumes cannot be fitted by a single-temperature plasma and display a range of temperatures from 0.2 to 1 keV. The plumes emerge from bright, diffuse circumnuclear emission in the inner 3 kpc centered on the Ha peak, which is displaced from the radio nuclei. There is a close morphological correspondence between the Ha and soft X-ray emission on all spatial scales. We interpret the plumes as a starburst-driven superwind and discuss two interpretations of the emission from the lobes in the context of simulations of the merger dynamics of Arp 220.

  17. ULTRAVIOLET/OPTICAL/INFRARED COLOR SEQUENCES ALONG THE TIDAL RING/ARM OF Arp 107

    SciTech Connect

    Lapham, Ryen C.; Smith, Beverly J.; Struck, Curtis E-mail: smithbj@etsu.edu

    2013-05-15

    We construct UV/optical/IR spectral energy distributions for 29 star forming regions in the interacting galaxy Arp 107, using GALEX UV, Sloan Digitized Sky Survey optical, and Spitzer infrared images. In an earlier study utilizing only the Spitzer data, we found a sequence in the mid-infrared colors of star-forming knots along the strong tidal arm in this system. In the current study, we find sequences in the UV/optical colors along the tidal arm that mirror those in the mid-infrared, with blue UV/optical colors found for regions that are red in the mid-infrared, and vice versa. With single-burst stellar population synthesis models, we find a sequence in the average stellar age along this arm, with younger stars preferentially located further out in the arm. Models that allow two populations of different ages and dust attenuations suggest that there may be both a young component and an older population present in these regions. Thus the observed color sequences may be better interpreted as a sequence in the relative proportion of young and old stars along the arm, with a larger fraction of young stars near the end. Comparison with star forming regions in other interacting galaxies shows that the Arp 107 regions are relatively quiescent, with less intense star formation than in many other systems.

  18. OPTICAL STRUCTURE AND EVOLUTION OF THE Arp 104 INTERACTING GALAXY SYSTEM

    SciTech Connect

    Gallagher, John S. III; Parker, Angela E-mail: parker@astro.indiana.ed

    2010-10-20

    Arp 104 is a pair of luminous interacting galaxies consisting of NGC 5216, an elliptical, and NGC 5218, a disturbed disk galaxy and joined by a stellar bridge. We obtained optical imaging to support photometric and color studies of the system. NGC 5216 lies on the red sequence, while the unusual distribution of stellar population properties in combination with intense central star formation in a dusty region result in NGC 5218 being a nearby example of an intermediate color (green valley) system. The stellar bridge has remarkably uniform optical surface brightness, with colors consistent with its stars coming from the outskirts of NGC 5218, but is relatively gas-poor while the northern tidal tail is rich in H I. While both galaxies contain shells, the shell structures in NGC 5218 are pronounced, and some appear to be associated with counter-rotating gas. This combination of features suggests that Arp 104 could be the product of distinct multiple interactions in a small galaxy group, possibly resulting from a hierarchical merging process, and likely leading to the birth of a relatively massive and isolated early-type galaxy.

  19. PWR ENDF/B-VII cross-section libraries for ORIGEN-ARP

    SciTech Connect

    McGraw, C.; Ilas, G.

    2012-07-01

    New pressurized water reactor (PWR) cross-section libraries were generated for use with the ORIGEN-ARP depletion sequence in the SCALE nuclear analysis code system. These libraries are based on ENDF/B-VII nuclear data and were generated using the two-dimensional depletion sequence, TRITON/NEWT, in SCALE 6.1. The libraries contain multiple burnup-dependent cross-sections for seven PWR fuel designs, with enrichments ranging from 1.5 to 6 wt% {sup 235}U. The burnup range has been extended from the 72 GWd/MTU used in previous versions of the libraries to 90 GWd/MTU. Validation of the libraries using radiochemical assay measurements and decay heat measurements for PWR spent fuel showed good agreement between calculated and experimental data. Verification against detailed TRITON simulations for the considered assembly designs showed that depletion calculations performed in ORIGEN-ARP with the pre-generated libraries provide similar results as obtained with direct TRITON depletion, while greatly reducing the computation time. (authors)

  20. Ultraviolet/Optical/Infrared Color Sequences along the Tidal Ring/Arm of Arp 107

    NASA Astrophysics Data System (ADS)

    Lapham, Ryen C.; Smith, Beverly J.; Struck, Curtis

    2013-05-01

    We construct UV/optical/IR spectral energy distributions for 29 star forming regions in the interacting galaxy Arp 107, using GALEX UV, Sloan Digitized Sky Survey optical, and Spitzer infrared images. In an earlier study utilizing only the Spitzer data, we found a sequence in the mid-infrared colors of star-forming knots along the strong tidal arm in this system. In the current study, we find sequences in the UV/optical colors along the tidal arm that mirror those in the mid-infrared, with blue UV/optical colors found for regions that are red in the mid-infrared, and vice versa. With single-burst stellar population synthesis models, we find a sequence in the average stellar age along this arm, with younger stars preferentially located further out in the arm. Models that allow two populations of different ages and dust attenuations suggest that there may be both a young component and an older population present in these regions. Thus the observed color sequences may be better interpreted as a sequence in the relative proportion of young and old stars along the arm, with a larger fraction of young stars near the end. Comparison with star forming regions in other interacting galaxies shows that the Arp 107 regions are relatively quiescent, with less intense star formation than in many other systems.

  1. Dense-gas properties in Arp 220 revealed by isotopologue lines

    NASA Astrophysics Data System (ADS)

    Wang, Junzhi; Zhang, Zhi-Yu; Zhang, Jiangshui; Shi, Yong; Fang, Min

    2016-02-01

    We present observations of isotopologue lines of dense-gas tracers at 3 mm and 1 mm towards the nearest ultra-luminous infrared galaxy Arp 220. The 3-mm and 1-mm observations were performed with the Institut de Radioastronomie Millimétrique 30-m telescope and the Atacama Pathfinder Experiment 12-m telescope, respectively. We detected H13CN and HN13C in 1-0 and 3-2, and HC15N 1-0, among which HC15N 1-0 and HN13C 1-0 are detected in Arp 220 for the first time. The H13CO+ 1-0 and 3-2 lines are unlikely to be detected because of the confusion of SiO lines. We find that the ratio of the line brightness temperatures of HN13C 3-2/1-0 is 2.4, which is significantly higher than that of H13CN 3-2/1-0 (0.73). This indicates that HN13C and HNC molecules are in denser regions than H13CN and HCN molecules. With the line ratio of H13CN 1-0 and HC15N 1-0, the 14N/15N ratio was estimated to be 440^{+140}_{-82}, which is larger than that of the local interstellar medium.

  2. Probing Momentum-Resolved Orbital Polarization at the Oxide Interfaces with SW-ARPES

    NASA Astrophysics Data System (ADS)

    Arab, Arian; Nemsak, Slavomir; Conti, Giuseppina; Strocov, Vladimir; Huijben, Mark; Minar, Jan; Fadley, Charles; Gray, Alexander

    Interface electronic structure is critical to the functional properties of strongly-correlated multilayer systems such as the La0.7Sr0.3MnO3/SrTiO3 heterostucture, a promising candidate for a magnetic tunnel junction. Recently it was demonstrated that for periodic superlattice samples controllable depth selectivity in angle-resolved photoemission spectroscopy (ARPES) can be accomplished by setting up an x-ray standing-wave (SW) field in the sample and translating it vertically along the surface normal by varying x-ray incidence angle. Here, by varying polarization of the incident x-rays we add orbital sensitivity to SW-ARPES, thus allowing us to distinguish momentum-resolved electronic dispersions for the electronic states of different symmetries (e.g. x2-y2 and 3z2-r2) . Distinctly different momentum-resolved orbital polarization maps are obtained for the bulk-like and interface-like Mn 3d electronic states. The results are compared to state-of-the-art first-principles calculations. Future directions and applications are discussed.

  3. ARPES-parameterized Hubbard approach to d-wave cuprate superconductors

    SciTech Connect

    Pérez, Luis A.; Galván, César G.; Wang, Chumin

    2014-01-27

    In the last decade, the Angle Resolved Photoemission Spectroscopy (ARPES) has achieved important advances in both energy and angular resolutions, providing a direct measurement of the single-particle dispersion relation and superconducting gap. These dispersion relation data allow a full determination of the self-energy, first and second neighbor parameters in the Hubbard model. This model and its generalizations offer a simple and general way to describe the electronic correlation in solids. In particular, the parameters of correlated hopping interactions, responsible of the d-wave superconductivity in the generalized Hubbard model, are determined from ARPES data and the critical temperature within the mean-field approximation. In this work, we determine the model parameters for Bi{sub 2}Sr{sub 2−x}La{sub x}CuO{sub 6+δ} and study its d-wave superconducting gap as a function of temperature by solving numerically two coupled integral equations. Finally, the calculated electronic specific heat is compared with experimental results.

  4. Molecular Gas in Starburts ARP 220 & NGC 6240: Understanding Mergers using High Density Gas Tracers

    NASA Astrophysics Data System (ADS)

    Manohar, Swarnima; Scoville, Nicholas; Sheth, Kartik

    2015-01-01

    NGC 6240 and Arp 220 can be considered the founding members of a very active class of objects called Ultraluminous Infrared Galaxies or ULIRGs. They are in different stages of mergers and hence are excellent case studies to enhance our knowledge about the merging process. We have imaged the dense star-forming regions of these galaxies at sub-arcsec resolution with ALMA and CARMA. Multi-band imaging allows multilevel excitation analysis of HCN, HCO+ and CS transitions which will constrain the properties of the gas as a function of position and velocity (across line profiles). We are doing an extensive multilevel excitation analysis of the merger as a function of radius which enables in depth understanding of the gas dynamics and gas properties such as temperature and density. This in turn probes the homogeneity of the gas in the merging system and hence the regions that facilitate high star formation rates. This tandem use of CARMA with ALMA to map these systems at different merger stages will assemble a more integrated picture of the merger process. We are probing the distribution and dynamics of star forming gas and star formation activity in the dense disk structures to enable new theoretical understanding of the physics, dynamics, star formation activity and associated feedback in the most active and rapidly evolving galactic nuclei. Here we present our observations of Arp 220 and NGC 6240 from ALMA and CARMA.

  5. Epitaxial growth and in situ ARPES of ultrathin YbAl3 thin films

    NASA Astrophysics Data System (ADS)

    Chatterjee, Shouvik; Schlom, Darrell; Shen, Kyle

    YbAl3 is a well-known intermediate valence compound that shows emergence of Fermi liquid behavior below a coherence temperature of ~34K - 40K. Transport, thermodynamic and photoemission measurements have established limitations of Single Impurity Anderson model in describing this material system, suggesting the importance of lattice effects. However, microscopic mechanisms underlying these properties are yet to be properly understood, one reason being that the direct experimental determination of its electronic band structure is still lacking. In this talk I will present our recent efforts in stabilizing thin films of YbAl3 and insitu angle-resolved photoemission spectroscopy (ARPES) of these films. With the aid of an Al buffer layer crystalline, phase pure and fully oriented epitaxial thin films can be grown with sub-nm surface roughness. By using ARPES, we, for the first time have been able to map out its band structure and Fermi surface. Moreover, by growing ultra thin films we have been able to drive this material system towards its 2D limit. Evolution of its electronic structure with temperature and dimensionality will be discussed.

  6. Phonon modes in cuprates possibly related to the 10 meV ARPES kink

    NASA Astrophysics Data System (ADS)

    Merritt, Adrian; Park, Seung-Ryong; Castellan, John-Paul; Gu, Genda; Reznik, Dmitry

    One of the possible mechanisms of high Tc superconductivity is Cooper pairing with the help of bosons responsible for kinks in electronic dispersion observed by angle-resolved photoemission (ARPES). Up to now most effort has been devoted to the kinks near 70 meV. More recent ARPES experiments revealed an additional energy scale near 10 meV. Since no magnetic excitations peaked at these energies have been identified, the likeliest candidates appear to be phonons. We recently performed measurements of low-energy phonons in a large single crystal sample of optimally-doped 2212 BSCCO. We measured all phonons below 15 meV. There are many branches, in particular an optic branch disperses from 7 meV from the zone center with an anticrossing with an acoustic branch near h =0.2. In addition, there is evidence for a very low energy branch dispersing through 3-4 meV. I will present these results as well as similar data on LSCO and YBCO. A comparison with recent ultrafast optics experiment detecting lattice modes around 10 meV will also be made. This work was supported by the DOE Basic Energy Sciences Neutron Scattering Program.

  7. KEY FACTORS THAT INFLUENCE THE PERFORMANCE PROPERTIES OF ARP/MCU SALTSTONE MIXES

    SciTech Connect

    Harbour, J.; Edwards, T.; Williams, V.

    2009-10-05

    At the Saltstone Production Facility (SPF), decontaminated salt solution (DSS) is combined with premix (a cementitious mixture of portland cement (PC), blast furnace slag (BFS) and Class F fly ash (FA)) in a Readco mixer to produce fresh (uncured) Saltstone. After transfer to the Saltstone Disposal Facility (SDF) the hydration reactions initiated during the contact of the premix and salt solution continue during the curing period to produce the hardened waste form product. The amount of heat generated from hydration and the resultant temperature increase in the vaults depend on the composition of the decontaminated salt solution being dispositioned as well as the grout formulation (mix design). This report details the results from Task 3 of the Saltstone Variability Study for FY09 which was performed to identify, and quantify when possible, those factors that drive the performance properties of the projected ARP/MCU Batches. A baseline ARP/MCU mix (at 0.60 water to cementitious materials (w/cm) ratio) was established and consisted of the normal premix composition and a salt solution that was an average of the projected compositions of the last three ARP/MCU batches developed by T. A. Le. This task introduced significant variation in (1) wt % slag, w/cm ratio, and wt % portland cement about the baseline mix and (2) the temperature of curing in order to better assess the dependence of the performance properties on these factors. Two separate campaigns, designated Phase 10 and Phase 11, were carried out under Task 3. Experimental designs and statistical analyses were used to search for correlation among properties and to develop linear models to predict property values based on factors such as w/cm ratio, slag concentration, and portland cement concentration. It turns out that the projected salt compositions contained relatively high amounts of aluminate (0.22 M) even though no aluminate was introduced due to caustic aluminate removal from High Level Waste. Previous

  8. Arp 65 interaction debris: massive H I displacement and star formation

    NASA Astrophysics Data System (ADS)

    Sengupta, C.; Scott, T. C.; Paudel, S.; Saikia, D. J.; Dwarakanath, K. S.; Sohn, B. W.

    2015-12-01

    Context. Pre-merger tidal interactions between pairs of galaxies are known to induce significant changes in the morphologies and kinematics of the stellar and interstellar medium components. Large amounts of gas and stars are often found to be disturbed or displaced as tidal debris. This debris then evolves, sometimes forming stars and occasionally forming tidal dwarf galaxies. Here we present results from our H i study of Arp 65, an interacting pair hosting extended H i tidal debris. Aims: In an effort to understand the evolution of tidal debris produced by interacting pairs of galaxies, including in situ star and tidal dwarf galaxy formation, we are mapping H i in a sample of interacting galaxy pairs. The Arp 65 pair is the latest member of this sample to be mapped. Methods: Our resolved H i 21 cm line survey is being carried out using the Giant Metrewave Radio Telescope. We used our H i survey data as well as available SDSS optical, Spitzer infra-red and GALEX UV data to study the evolution of the tidal debris and the correlation of H i with the star-forming regions within it. Results: In Arp 65 we see a high impact pre-merger tidal interaction involving a pair of massive galaxies (NGC 90 and NGC 93) that have a stellar mass ratio of ~1:3. The interaction, which probably occurred ~1.0-2.5 × 108 yr ago, appears to have displaced a large fraction of the H i in NGC 90 (including the highest column density H i) beyond its optical disk. We also find extended on-going star formation in the outer disk of NGC 90. In the major star-forming regions, we find the H i column densities to be ~4.7 × 1020 cm-2 or lower. But no signature of star formation was found in the highest column density H i debris SE of NGC 90. This indicates conditions within the highest density H i debris remain hostile to star formation and it reaffirms that high H i column densities may be a necessary but not sufficient criterion for star formation.

  9. Bilberry (Vaccinium myrtillus) Anthocyanins Modulate Heme Oxygenase-1 and Glutathione S-Transferase-pi Expression in the ARPE-19 Cells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    PURPOSE. To determine whether anthocyanin-enriched bilberry extracts modulate pre- or post-translational levels of oxidative stress defense enzymes heme-oxygenase (HO)-1 and glutathione S-transferase-pi (GST-pi) in cultured human retinal pigment epithelial (RPE) cells. METHODS. Confluent ARPE-19 c...

  10. Tissue factor induces VEGF expression via activation of the Wnt/β-catenin signaling pathway in ARPE-19 cells

    PubMed Central

    Wang, Ying; Sang, Aimin; Zhu, Manhui; Zhang, Guowei; Guan, Huaijin; Ji, Min

    2016-01-01

    Purpose The purpose of the present study was to investigate the potential signal mechanism of tissue factor (TF) in the regulation of the expression of vascular endothelial growth factor (VEGF) in human retinal pigment epithelial (ARPE-19) cells. Methods An in vitro RPE cell chemical hypoxia model was established by adding cobalt chloride (CoCl2) in the culture medium. The irritative concentration of CoCl2 was determined with a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay kit. VEGF production in ARPE-19 cells was measured with enzyme-linked immunosorbent assay (ELISA) and western blotting. The Wnt signaling pathway–associated molecules, including phospho-glycogen synthase kinase 3β (p-GSK3β), GSK3β, p-β-catenin and β-catenin, were detected with western blotting. pEGFP-N3-hTF was constructed and verified with digestion of the restriction enzyme and sequencing analysis. Human TF overexpression and silencing plasmids were transfected into the ARPE-19 cells to clarify the causal relationship between TF and VEGF expression. The Transwell coculture system of ARPE-19 cells and RF/6A rhesus macaque choroid–retinal endothelial cells was performed to evaluate cell invasion and tube formation ability. Results Our anoxic model of ARPE-19 cells showed that TF expression was upregulated in accordance with variations in hypoxia-inducible factor 1-alpha (HIF-1α) and VEGF levels. Silencing and overexpression of TF decreased and increased VEGF expression, respectively. The Wnt/β-catenin signaling pathway played an important role in this effect. Results from the ARPE-19 cell and RF/6A cell coculture system showed that the enhancement of TF expression in the ARPE-19 cells led to significantly faster invasion and stronger tube-forming ability of the RF/6A cells, while siRNA-mediated TF silencing caused the opposite effects. Pharmacological disruption of Wnt signaling IWR-1-endo inhibited the effects compared to the TF-overexpressing group

  11. Far-infrared spectroscopy of NGC 6946, IC 342, and Arp 299

    NASA Technical Reports Server (NTRS)

    Lord, Steven D.; Hollenbach, David J.; Colgan, Sean W. J.; Haas, Michael R.; Rubin, Robert H.; Erickson, Edwin F.

    1990-01-01

    Researchers investigated the physical conditions in the infrared bright galaxies NGC 6946, IC 342, and Arp 299 through measurements of far-infrared emission lines from Si II, O I, C II, and O III using the facility Cooled Grating Spectrometer on the Kuiper Airborne Observatory. These data are interpreted using our theoretical models for photodissociation regions and H II regions. For the central 45 inches of these galaxies, researchers determined that the dominant excitation mechanism for the far infrared radiation (FIR) lines is far ultraviolet radiation (FUR) radiation from young stars, and the authors derived the total mass, density, and temperature of the warm atomic gas and the typical sizes, number densities, and filling factors for the interstellar clouds.

  12. Detecting the minimum gap locus in ARPES spectra of Bi2201

    NASA Astrophysics Data System (ADS)

    Hashimoto, Makoto; He, Ruihua; Moore, Rob; Lu, Donghui; Yoshida, Yoshiyuki; Ishikado, Motoyuki; Eisaki, Hiroshi; Hussain, Zahid; Devereaux, Tom; Shen, Zhi-Xun

    2012-02-01

    Recent angle-resolved photoemission (ARPES) studies have reported a direct evidence for the competing nature of the pseudogap by showing that the pseudogap dispersion is not tied to Fermi momentum (kF)[1,2]. In this study, to get more detailed information on how the competing pseudogap evolves across the pseudogap temperature (T*), we introduce a new analysis method for spectral weight. We found a clear indication that the pseudogap opens at T* with the minimum gap locus deviating from kF, which is completely different manner from the gap opening by simple superconductivity, and strongly supports that the pseudogap is another distinct order. [1] M. Hashimoto and R.-H. He et al., Nature Phys. 6, 14-418 (2010). [2] R.-H. He and M. Hashimoto et al., Science 331, 1579-1583 (2011).

  13. Arp2/3-mediated F-actin formation controls regulated exocytosis in vivo

    PubMed Central

    Tran, Duy T.; Masedunskas, Andrius; Weigert, Roberto; Ten Hagen, Kelly G.

    2015-01-01

    The actin cytoskeleton plays crucial roles in many cellular processes, including regulated secretion. However, the mechanisms controlling F-actin dynamics in this process are largely unknown. Through 3D time-lapse imaging in a secreting organ, we show that F-actin is actively disassembled along the apical plasma membrane at the site of secretory vesicle fusion and re-assembled directionally on vesicle membranes. Moreover, we show that fusion pore formation and PIP2 redistribution precedes actin and myosin recruitment to secretory vesicle membranes. Finally, we show essential roles for the branched actin nucleators Arp2/3- and WASp in the process of secretory cargo expulsion and integration of vesicular membranes with the apical plasma membrane. Our results highlight previously unknown roles for branched actin in exocytosis and provide a genetically tractable system to image the temporal and spatial dynamics of polarized secretion in vivo. PMID:26639106

  14. Kinematics and excitation of the nuclear spiral in the active galaxy Arp 102B

    NASA Astrophysics Data System (ADS)

    Couto, Guilherme S.; Storchi-Bergmann, Thaisa; Axon, David J.; Robinson, Andrew; Kharb, Preeti; Riffel, Rogemar A.

    2013-11-01

    We present a two-dimensional analysis of the gaseous excitation and kinematics of the inner 2.5 × 1.7 kpc2 of the low-ionization nuclear emission-line region (LINER)/Seyfert 1 galaxy Arp 102B, from optical spectra obtained with the Gemini Multi-Object Spectrograph Integral Field Unit on the Gemini North telescope at a spatial resolution of ≈250 pc. Emission-line flux maps show the same two-armed nuclear spiral we have discovered in previous observations with the Hubble Space Telescope Advanced Camera for Surveys. One arm reaches 1 kpc to the east and the other 500 pc to the west, with an 8.4 GHz Very Large Array bent radio jet correlating with the former. Gas excitation along the arms is low, with line ratios typical of LINERs, and which rule out gas ionization by stars. The gas density is highest (≈500-900 cm-3) at the nucleus and in the northern border of the east arm, at a region where the radio jet seems to be deflected. Centroid velocity maps suggest that most gas is in rotation in an inclined disc with line of nodes along position angle ≈88°, redshifts to the west and blueshifts to the east, with lower blueshifts correlated with the eastern arm and radio jet. This correlation suggests that the jet is interacting with gas in the disc. This interaction is supported by the gas excitation as a function of distance from the nucleus, which requires the contribution from shocks. Channel maps show blueshifts but also some redshifts at the eastern arm and jet location which can be interpreted as originated in the front and back walls of an outflow pushed by the radio jet, suggesting also that the outflow is launched close to the plane of the sky. Principal Component Analysis applied to our data supports this interpretation. We estimate a mass outflow rate along the east arm of 0.26-0.32 M⊙ yr- 1 (depending on the assumed outflow geometry), which is between one and two orders of magnitude higher than the mass accretion rate to the active nucleus, implying

  15. ARPES: Novel effects in the energy and momentum distributions of nearly antiferromagnetic metals

    SciTech Connect

    Kampf, A.P.; Schrieffer, J.R.

    1996-12-31

    The physical origin of two effects, i.e. shadow bands and three peaked energy spectra in the ARPES and inverse photoemission spectra of strongly correlated electron systems, such as the cuprates, are discussed. Shadow bands arise from quasi elastic exchange Bragg scattering from residual antiferromagnetic spin correlations in the paramagnetic phase. Three peaked energy spectra arise as a superposition of the central Landau quasi particle peak of the weakly correlated system and the upper and lower band peaks split by the SDW and/or Mott-Hubbard pseudo gap 2{Delta} of the strongly correlated system. The coexistence of these three resonances is explained in terms of quasi particles propagating in a medium with {Sigma}(k,{omega}) exhibiting strong anomalous dispersion, i.e. multiple fermionic modes for fixed k, analogous to multiple sound modes in superfluid {sup 3}He and {sup 4}He.

  16. Arp2/3-mediated F-actin formation controls regulated exocytosis in vivo.

    PubMed

    Tran, Duy T; Masedunskas, Andrius; Weigert, Roberto; Ten Hagen, Kelly G

    2015-01-01

    The actin cytoskeleton plays crucial roles in many cellular processes, including regulated secretion. However, the mechanisms controlling F-actin dynamics in this process are largely unknown. Through 3D time-lapse imaging in a secreting organ, we show that F-actin is actively disassembled along the apical plasma membrane at the site of secretory vesicle fusion and re-assembled directionally on vesicle membranes. Moreover, we show that fusion pore formation and PIP2 redistribution precedes actin and myosin recruitment to secretory vesicle membranes. Finally, we show essential roles for the branched actin nucleators Arp2/3- and WASp in the process of secretory cargo expulsion and integration of vesicular membranes with the apical plasma membrane. Our results highlight previously unknown roles for branched actin in exocytosis and provide a genetically tractable system to image the temporal and spatial dynamics of polarized secretion in vivo. PMID:26639106

  17. Kinematic properties of superbubbles in the Antennae, M83 and Arp 270

    NASA Astrophysics Data System (ADS)

    Camps-Fariña, A.; Beckman, J.; Zaragoza-Cardiel, J.; Font, J.; Fathi, K.; Velázquez, P. Fabian; Rodríguez-González, A.

    2015-02-01

    Superbubbles and large scale expansion in galaxies are important indicators of activity in galaxies: they are formed in starbursts and around active nuclei. Superbubbles can be used to give information about the star-forming region which produced them. We present in-depth results of our study of kinematically detected superbubbles using a method based on Fabry-Perot spectroscopy, which allows us to map regions of expansion across the entire disk of a galaxy. Three objects have been selected for this poster based on the interest of the results they show: two interacting galaxies, the Antennae and Arp270, at different stages of galaxy interaction, and the more isolated galaxy M83. We present the kinematic expansion maps, as well as a census of detected superbubbles and a dynamical study of their properties.

  18. Influence of arthritis-related protein (BBF01) on infectivity of Borrelia burgdorferi B31

    PubMed Central

    2013-01-01

    Background Lyme borreliosis, caused by tick-borne Borrelia burgdorferi, is a multi-phasic, multi-system disease in humans. Similar to humans, C3H mice develop arthritis and carditis, with resolution and periodic bouts of recurrence over the course of persistent infection. Borrelia burgdorferi arthritis-related protein (Arp/BBF01), a highly conserved protein among B. burgdorferi s.s. isolates, has been shown to be antigenic in humans with Lyme borreliosis, and a target for antibody-mediated disease resolution in the mouse model. Results A mutant strain of B. burgdorferi s.s. deficient of the arp gene and a complemented version of that mutant were created and examined for phenotypic effects in mice compared to wild-type B. burgdorferi. Deletion of arp did not abolish infectivity, but did result in a higher infectious dose compared to wild-type B. burgdorferi, which was restored by complementation. Spirochete burdens in tissues of C3H-scid mice were lower when infected with the arp mutant, compared to wild-type, but arthritis was equally severe. Spirochete burdens were also lower in C3H mice infected with the arp mutant, but disease was markedly reduced. Ticks that fed upon infected C3H mice were able to acquire infection with both wild-type and arp mutant spirochetes. Arp mutant spirochetes were marginally able to be transmitted to naïve hosts by infected ticks. Conclusion These results indicated that deletion of BBF01/arp did not abrogate, but diminished infectivity and limited spirochete burdens in tissues of both immunocompetent and immunodeficient hosts, and attenuated, but did not abolish the ability of ticks to acquire or transmit infection. PMID:23651628

  19. Herschel spectroscopic observations of Zw 049.057 and Arp 299

    NASA Astrophysics Data System (ADS)

    Falstad, Niklas; Aalto, Susanne; González-Alfonso, Eduardo

    2015-08-01

    Luminous infrared galaxies (LIRGs) are extreme examples of star-forming galaxies or galaxies with active galactic nuclei (AGN), often interacting or merging systems, whose high infrared luminosities are powered by their intense star formation or AGN activity. Through studying molecular species that are mainly excited by warm dust emission (i.e. OH, H2O) it is possible to probe the nuclear source of far-IR radiation and gain insights in its physical conditions and chemistry.We present the results and analysis of Herschel observations of the compact obscured nucleus in the extremely H2O luminous LIRG Zw 049.057. We model the H2O and OH lines and continuum using a spherically symmetric radiative transfer code. We find that the far-IR absorption lines are primarily formed in a Compton-thick warm (Tdust>100 K) core with high columns of H2O and OH (similar to the nuclear regions of the ULIRG Arp 220). We also find an enhancement of 18O in the core component, suggesting that the ISM has been enriched by ejecta from massive stars.One of the low excited H2O lines exhibit an emission feature extending up to 500 km/s, suggesting an outflow. At the same time, we find a prominent infall signature in the [O I] 63 µm line, implying that the gas reservoir in the central region of Zw 049.057 is being replenished. The presence of both outflowing and infalling gas suggests that the nucleus is in a state of rapid evolution.We also present observations of the luminous merger Arp 299. This is another source with prominent H2O and OH lines, but preliminary results suggest that its nuclear activity is in a different evolutionary state compared to Zw 049.057.

  20. AN H{alpha} NUCLEAR SPIRAL STRUCTURE IN THE E0 ACTIVE GALAXY Arp 102B

    SciTech Connect

    Fathi, Kambiz; Axon, David J.; Kharb, Preeti; Robinson, Andrew; Storchi-Bergmann, Thaisa; Marconi, Alessandro; Maciejewski, Witold; Capetti, Alessandro E-mail: djasps@rit.edu E-mail: pxksps@cis.rit.edu E-mail: marconi@arcetri.astro.it E-mail: capetti@to.astro.it

    2011-08-01

    We report the discovery of a two-armed mini-spiral structure within the inner kiloparsec of the E0 LINER/Seyfert 1 galaxy Arp 102B. The arms are observed in H{alpha} emission and located east and west of the nucleus, extending up to {approx}1 kpc from it. We use narrow-band imaging from the Hubble Space Telescope Advanced Camera for Surveys, in combination with archival Very Large Array radio images at 3.6 and 6 cm to investigate the origin of the nuclear spiral. From the H{alpha} luminosity of the spiral, we obtain an ionized gas mass of the order of 10{sup 6} solar masses. One possibility is that the nuclear spiral represents a gas inflow triggered by a recent accretion event which has replenished the accretion disk, giving rise to the double-peaked emission-line profiles characteristic of Arp 102B. However, the radio images show a one-sided curved jet which correlates with the eastern spiral arm observed in the H{alpha} image. A published milliarcsecond radio image also shows a one-sided structure at position angle {approx}40{sup 0}, approximately aligned with the inner part of the eastern spiral arm. The absence of a radio counterpart to the western spiral arm is tentatively interpreted as indicating that the jet is relativistic, with an estimated speed of 0.45c. Estimates of the jet kinetic energy and the ionizing luminosity of the active nucleus indicate that both are capable of ionizing the gas along the spiral arms. We conclude that, although the gas in the nuclear region may have originated in an accretion event, the mini spiral is most likely the result of a jet-cloud interaction rather than an inflowing stream.

  1. Multiple A2E treatments lead to melanization of rod outer segment–challenged ARPE-19 cells

    PubMed Central

    Poliakov, Eugenia; Strunnikova, Natalya V.; Jiang, Jian-kang; Martinez, Bianca; Parikh, Toral; Lakkaraju, Aparna; Thomas, Craig; Brooks, Brian P.

    2014-01-01

    Purpose Daily phagocytosis of outer segments (OSs) and retinoid recycling by the RPE lead to the accumulation of storage bodies in the RPE containing autofluorescent lipofuscin, which consists of lipids and bisretinoids such as A2E and its oxidation products. Accumulation of A2E and its oxidation products is implicated in the pathogenesis of several retinal degenerative diseases. However, A2E accumulates in the RPE during normal aging. In this study, we used a cell model to determine the homeostatic mechanisms of RPE cells in response to A2E accumulation. Methods To distinguish between pathologic and normal responses of the RPE to A2E accumulation, we treated established ARPE-19 cells (cultured for 3 weeks after reaching confluence) with low micromolar amounts of A2E for several weeks. We compared the lysosomal function, lysosomal pH, degree of OS digestion, and melanization of the treated cells to untreated control cells in response to a challenge of purified rod OSs (ROSs). A2E was analyzed with high-performance liquid chromatography (HPLC); and A2E and melanin were identified with mass spectrometry. Results We found that post-confluent ARPE-19 cells took up and accumulated A2E under dim light conditions. Spectral analysis of the HPLC separations and mass spectrometry showed that A2E-fed cells contained A2E and oxidized A2E (furan-A2E). A2E accumulation led to a modest increase (up to 0.25 unit) in lysosomal pH in these cells. The specific activity of cathepsin D and lysosomal acid phosphatase was reduced in the A2E-treated cells, but ROS degradation was not impaired. We found that, upon challenge with ROSs, melanin pigment was induced in the lysosomal fraction of the A2E-treated ARPE-19 cells. Thus, the ARPE-19 cells responded to the A2E treatment and ROS challenge by producing a melanin-containing lysosome fraction. We speculate that this prevents them from becoming impaired in OS processing. Conclusions We used a modified ARPE-19 cell model in which

  2. Strategies of ARP application (Automatic Resistivity Profiling) for viticultural precision farming

    NASA Astrophysics Data System (ADS)

    Costantini, E. A. C.; Andrenelli, M. C.; Bucelli, P.; Magini, S.; Natarelli, L.; Pellegrini, S.; Perria, R.; Storchi, P.; Vignozzi, N.

    2009-04-01

    Introduction Viticultural precision farming needs detailed soil information, which can be obtained by means of remote as well as proximal sensors, besides traditional invasive soil survey. Nevertheless, the use of the new technologies is still in its infancy, because of their costs and the lack of knowledge about the detail actually needed for the viticultural husbandry. The main aim of this work was to test the sensitivity of the ARP methodology (Automatic Resistivity Profiling) in supporting soil survey for viticultural precision farming. In addition, we tried to optimize the detail of geoelectrical measurements and soil sampling to reduce the cost of the integrated survey, maintaining a significant information accuracy for viticulture. Materials and methods Two vineyards in coastal Tuscany (central Italy), about 3.5 ha each, were selected. Vineyard 1 was cultivated with Cabernet Sauvignon and Cabernet Franc, while vineyard 2 only had Cabernet Sauvignon. Soil survey and geoelectrical investigation were conducted in may 2007. The ARP methodology consists in the injection in soil of electric current through one pair of electrodes mounted on teeth wheels and measuring the resulting potential with other three pairs of electrodes, placed of the same mobile equipment. The electrical resistance of the soil (ER) is expressed as ohm per m. The depth of investigation is a function of the geometry of the electrodes and the soil being probed. Increasing the distance between electrodes will increase the depth while decreasing the measured potential. The innovative character of the ARP technique is represented by the passage of a mobile machinery, able to perform 30,000 measurements per hectare, with a measurement every 0.2 m. The ARP system, equipped with a digital encoder and DGPS system, is transported by a four-wheeled vehicle. It is fitted with three sensors that contemporaneously analyse three distinct levels of the soil, the values of which are represented by maps of

  3. OPERATIONAL AND COMPOSITIONAL FACTORS THAT AFFECT THE PERFORMANCE PROPERTIES OF ARP/MCU SALTSTONE GROUT

    SciTech Connect

    Reigel, M.; Edwards, T.; Pickenheim, B.

    2012-02-15

    The Saltstone Production Facility (SPF) receives low level waste (LLW) salt solution from Tank 50H for treatment and disposal. Tank 50H receives transfers from the Effluent Treatment Project (ETP), the H-Canyon General Purpose Evaporator, and the Actinide Removal Process/Modular Caustic Side Solvent Extraction Unit (ARP/MCU) Decontaminated Salt Solution Hold Tank (DSS-HT). At the SPF, the LLW is mixed with premix (a cementitious mixture of portland cement (PC), blast furnace slag (BFS) and Class F fly ash (FA)) in a Readco mixer to produce fresh (uncured) saltstone that is transferred to the Saltstone Disposal Facility (SDF) vaults. The saltstone formulation (mix design) must produce a grout waste form that meets both placement and performance properties. In previous simulated saltstone studies, multiple compositional factors were identified that drive the performance properties of saltstone made from the projected ARP/MCU salt solution. This composition was selected as salt solution simulant since ARP/MCU is the primary influent into Tank 50H. The primary performance property investigated was hydraulic conductivity since it is a variable input property to the saltstone Performance Assessment (PA) transport model. In addition, the porosity, also referred to as void structure, is another variable that impacts the PA response. In addition, Young's modulus and cured density are other performance properties analyzed in this report; however they are indicators of the performance of saltstone and not direct inputs into the PA. The data from previous studies showed that the largest impact on the performance properties of saltstone was due to curing temperature, followed by aluminate concentration in the salt solution, water to premix ratio and premix composition. However, due to the scope of the previous studies, only a few mixes were cured and analyzed at higher temperatures. The samples cured at 60 C had an increased hydraulic conductivity of approximately 600 times

  4. Chlamydia trachomatis Tarp cooperates with the Arp2/3 complex to increase the rate of actin polymerization

    PubMed Central

    Jiwani, Shahanawaz; Ohr, Ryan J.; Fischer, Elizabeth R.; Hackstadt, Ted; Alvarado, Stephenie; Romero, Adriana; Jewett, Travis J.

    2012-01-01

    Actin polymerization is required for Chlamydia trachomatis entry into nonphagocytic host cells. Host and chlamydial actin nucleators are essential for internalization of chlamydiae by eukaryotic cells. The host cell Arp2/3 complex and the chlamydial translocated actin recruiting phosphoprotein (Tarp) are both required for entry. Tarp and the Arp2/3 complex exhibit unique actin polymerization kinetics individually, but the molecular details of how these two actin nucleators cooperate to promote bacterial entry is not understood. In this study we provide biochemical evidence that the two actin nucleators act synergistically by co-opting the unique attributes of each to enhance the dynamics of actin filament formation. This process is independent of Tarp phosphorylation. We further demonstrate that Tarp colocalization with actin filaments is independent of the Tarp phosphorylation domain. The results are consistent with a model in which chlamydial and host cell actin nucleators cooperate to increase the rate of actin filament formation. PMID:22465117

  5. ORIGEN-ARP Cross-Section Libraries for Magnox, Advanced Gas-Cooled, and VVER Reactor Designs

    SciTech Connect

    Murphy, BD

    2004-03-10

    Cross-section libraries for the ORIGEN-ARP system were extended to include four non-U.S. reactor types: the Magnox reactor, the Advanced Gas-Cooled Reactor, the VVER-440, and the VVER-1000. Typical design and operational parameters for these four reactor types were determined by an examination of a variety of published information sources. Burnup simulation models of the reactors were then developed using the SAS2H sequence from the Oak Ridge National Laboratory SCALE code system. In turn, these models were used to prepare the burnup-dependent cross-section libraries suitable for use with ORIGEN-ARP. The reactor designs together with the development of the SAS2H models are described, and a small number of validation results using spent-fuel assay data are reported.

  6. Actin Interacts with Dengue Virus 2 and 4 Envelope Proteins

    PubMed Central

    Jitoboam, Kunlakanya; Phaonakrop, Narumon; Libsittikul, Sirikwan; Thepparit, Chutima; Roytrakul, Sittiruk; Smith, Duncan R.

    2016-01-01

    Dengue virus (DENV) remains a significant public health problem in many tropical and sub-tropical countries worldwide. The DENV envelope (E) protein is the major antigenic determinant and the protein that mediates receptor binding and endosomal fusion. In contrast to some other DENV proteins, relatively few cellular interacting proteins have been identified. To address this issue a co-immuoprecipitation strategy was employed. The predominant co-immunoprecipitating proteins identified were actin and actin related proteins, however the results suggested that actin was the only bona fide interacting partner. Actin was shown to interact with the E protein of DENV 2 and 4, and the interaction between actin and DENV E protein was shown to occur in a truncated DENV consisting of only domains I and II. Actin was shown to decrease during infection, but this was not associated with a decrease in gene transcription. Actin-related proteins also showed a decrease in expression during infection that was not transcriptionally regulated. Cytoskeletal reorganization was not observed during infection, suggesting that the interaction between actin and E protein has a cell type specific component. PMID:27010925

  7. CHEMICALLY DISTINCT NUCLEI AND OUTFLOWING SHOCKED MOLECULAR GAS IN Arp 220

    SciTech Connect

    Tunnard, R.; Greve, T. R.; Garcia-Burillo, S.; Fuente, A.; Usero, A.; Planesas, P.; Carpio, J. Graciá; Hailey-Dunsheath, S.; Sturm, E.; Fischer, J.; González-Alfonso, E.; Neri, R.

    2015-02-10

    We present the results of interferometric spectral line observations of Arp 220 at 3.5 mm and 1.2 mm from the Plateau de Bure Interferometer, imaging the two nuclear disks in H{sup 13}CN(1-0) and (3-2), H{sup 13}CO{sup +}(1-0) and (3-2), and HN{sup 13}C(3-2) as well as SiO(2-1) and (6-5), HC{sup 15}N(3-2), and SO(6{sub 6}-5{sub 5}). The gas traced by SiO(6-5) has a complex and extended kinematic signature including a prominent P Cygni profile, almost identical to previous observations of HCO{sup +}(3-2). Spatial offsets 0.''1 north and south of the continuum center in the emission and absorption of the SiO(6-5) P Cygni profile in the western nucleus (WN) imply a bipolar outflow, delineating the northern and southern edges of its disk and suggesting a disk radius of ∼40 pc, consistent with that found by ALMA observations of Arp 220. We address the blending of SiO(6-5) and H{sup 13}CO{sup +}(3-2) by considering two limiting cases with regards to the H{sup 13}CO{sup +} emission throughout our analysis. Large velocity gradient modeling is used to constrain the physical conditions of the gas and to infer abundance ratios in the two nuclei. Our most conservative lower limit on the [H{sup 13}CN]/[H{sup 13}CO{sup +}] abundance ratio is 11 in the WN, compared with 0.10 in the eastern nucleus (EN). Comparing these ratios to the literature we argue on chemical grounds for an energetically significant active galactic nucleus in the WN driving either X-ray or shock chemistry, and a dominant starburst in the EN.

  8. INTEGRAL Field Spectroscopy of the Extended Ionized Gas in Arp 220

    NASA Astrophysics Data System (ADS)

    Colina, Luis; Arribas, Santiago; Clements, David

    2004-02-01

    Integral field optical spectroscopy with the INTEGRAL system has been used to investigate for the first time the two-dimensional kinematic and ionization properties of the extended, warm, ionized gas in Arp 220 over an area of 75.0"×40.0" (i.e., 28×15 kpc). The structure of the ionized gas is divided into well-identified regions associated with the X-ray-emitting plumes and extended lobes, previously studied in detail by McDowell and collaborators. The overall ionization state of the warm gas in the plumes and lobes, as traced by the [N II]/Hα line, is consistent with high-velocity shocks expanding in a neutral ambient medium. Changes in the ionization state of the gas along the major axis of the plumes are detected, in particular in the outer regions of the northwestern plume, where the transition between the main stellar body of the galaxy and a broad, low surface brightness tidal tail is located. If the plumes are produced by a starburst-driven galactic wind, the efficiency in the conversion of mechanical to radiation energy is a factor of at least 10 smaller than in galactic winds developed in edge-on spiral galaxies with well-defined rotation and axis of outflow. The kinematic properties of the lobes, with an average velocity of +8 km s-1 (east lobe) and -79 km s-1 (west lobe), are to a first order in agreement with the predictions of the merger scenario, according to which the lobes are tidally induced gas condensations produced during the merging process. The largest velocity gradients of 50 km s-1 kpc-1 and velocity deviations of up to +280 and -320 km s-1 from the systemic velocity are associated not with the plumes but with the outer stellar envelope and broad tidal tails at distances of up to 7.5 kpc, indicating that the large-scale kinematics of the extended ionized gas in Arp 220 is most likely dominated by the tidally induced motions, and not by galactic winds associated with nuclear starbursts. Based on observations with the William Herschel

  9. LUMINOUS INFRARED GALAXIES WITH THE SUBMILLIMETER ARRAY. III. THE DENSE KILOPARSEC MOLECULAR CONCENTRATIONS OF Arp 299

    SciTech Connect

    Sliwa, Kazimierz; Wilson, Christine D.; Petitpas, Glen R.; Armus, Lee; Juvela, Mika; Matsushita, Satoki; Peck, Alison B.; Yun, Min S. E-mail: wilson@physics.mcmaster.ca E-mail: lee@ipac.caltech.edu E-mail: satoki@asiaa.sinica.edu.tw E-mail: myun@astro.umass.edu

    2012-07-01

    We have used high-resolution ({approx}2.''3) observations of the local (D{sub L} = 46 Mpc) luminous infrared galaxy Arp 299 to map out the physical properties of the molecular gas that provides the fuel for its extreme star formation activity. The {sup 12}CO J = 3-2, {sup 12}CO J = 2-1, and {sup 13}CO J = 2-1 lines were observed with the Submillimeter Array, and the short spacings of the {sup 12}CO J = 2-1 and J = 3-2 observations have been recovered using the James Clerk Maxwell Telescope single dish observations. We use the radiative transfer code RADEX to estimate the physical properties (density, column density, and temperature) of the different regions in this system. The RADEX solutions of the two galaxy nuclei, IC 694 and NGC 3690, are consistent with a wide range of gas components, from warm moderately dense gas with T{sub kin} > 30 K and n(H{sub 2}) {approx} 0.3-3 Multiplication-Sign 10{sup 3} cm{sup -3} to cold dense gas with T{sub kin} {approx} 10-30 K and n(H{sub 2}) > 3 Multiplication-Sign 10{sup 3} cm{sup -3}. The overlap region is shown to have a better constrained solution with T{sub kin} {approx} 10-50 K and n(H{sub 2}) {approx} 1-30 Multiplication-Sign 10{sup 3} cm{sup -3}. We estimate the gas masses and star formation rates of each region in order to derive molecular gas depletion times. The depletion times of all regions (20-50 Myr) are found to be about two orders of magnitude lower than those of normal spiral galaxies. This rapid depletion time can probably be explained by a high fraction of dense gas on kiloparsec scales in Arp 299. We estimate the CO-to-H{sub 2} factor, {alpha}{sub co} to be 0.4 {+-} 0.3(3 Multiplication-Sign 10{sup -4}/x{sub CO}) M{sub Sun} (K km s{sup -1} pc{sup 2}){sup -1} for the overlap region. This value agrees well with values determined previously for more advanced merger systems.

  10. Uncovering the Deeply Embedded Active Galactic Nucleus Activity in the Nuclear Regions of the Interacting Galaxy Arp 299

    NASA Astrophysics Data System (ADS)

    Alonso-Herrero, A.; Roche, P. F.; Esquej, P.; González-Martín, O.; Pereira-Santaella, M.; Ramos Almeida, C.; Levenson, N. A.; Packham, C.; Asensio Ramos, A.; Mason, R. E.; Rodríguez Espinosa, J. M.; Alvarez, C.; Colina, L.; Aretxaga, I.; Díaz-Santos, T.; Perlman, E.; Telesco, C. M.

    2013-12-01

    We present mid-infrared (MIR) 8-13 μm spectroscopy of the nuclear regions of the interacting galaxy Arp 299 (IC 694+NGC 3690) obtained with CanariCam (CC) on the 10.4 m Gran Telescopio Canarias (GTC). The high angular resolution (~0.''3-0.''6) of the data allows us to probe nuclear physical scales between 60 and 120 pc, which is a factor of 10 improvement over previous MIR spectroscopic observations of this system. The GTC/CC spectroscopy displays evidence of deeply embedded active galactic nucleus (AGN) activity in both nuclei. The GTC/CC nuclear spectrum of NGC 3690/Arp 299-B1 can be explained as emission from AGN-heated dust in a clumpy torus with both a high covering factor and high extinction along the line of sight. The estimated bolometric luminosity of the AGN in NGC 3690 is 3.2 ± 0.6 × 1044 erg s-1. The nuclear GTC/CC spectrum of IC 694/Arp 299-A shows 11.3 μm polycyclic aromatic hydrocarbon emission stemming from a deeply embedded (AV ~ 24 mag) region of less than 120 pc in size. There is also a continuum-emitting dust component. If associated with the putative AGN in IC 694, we estimate that it would be approximately five times less luminous than the AGN in NGC 3690. The presence of dual AGN activity makes Arp 299 a good example to study such phenomena in the early coalescence phase of interacting galaxies.

  11. Evaluation of ShARP Passive Rainfall Retrievals over Snow-Covered Land Surfaces and Coastal Zones

    NASA Astrophysics Data System (ADS)

    Ebtehaj, Ardeshir M.; Bras, Rafael L.; Foufoula-Georgiou, Efi

    2016-04-01

    For precipitation retrievals over land, using satellite measurements in microwave bands, it is important to properly discriminate the weak rainfall signals from strong and highly variable background surface emission. Traditionally, land rainfall retrieval methods often rely on a weak signal of rainfall scattering on high-frequency channels (85 GHz) and make use of empirical thresholding and regression-based techniques. Due to the increased ground surface signal interference, precipitation retrieval over radiometrically complex land surfaces, especially over snow-covered lands, deserts and coastal areas, is of particular challenge for this class of retrieval techniques. This paper evaluates the results by the recently proposed Shrunken locally linear embedding Algorithm for Retrieval of Precipitation (ShARP), over a radiometrically complex terrain and coastal areas using the data provided by the Tropical Rainfall Measuring Mission (TRMM) satellite. To this end, the ShARP retrieval experiments are performed over a region in Southeast Asia, partly covering the Tibetan Highlands, Himalayas, Ganges-Brahmaputra-Meghna river basins and its delta. We elucidate promising results by ShARP over snow covered land surfaces and at the vicinity of coastlines, in comparison with the land rainfall retrievals of the standard TRMM-2A12 product. Specifically, using the TRMM-2A25 radar product as a reference, we provide evidence that the ShARP algorithm can significantly reduce the rainfall over estimation due to the background snow contamination and markedly improve detection and retrieval of rainfall at the vicinity of coastlines. During the calendar year 2013, we demonstrate that over the study domain the root mean squared difference can be reduced up to 38% annually, while the reduction can reach up to 70% during the cold months.

  12. UNCOVERING THE DEEPLY EMBEDDED ACTIVE GALACTIC NUCLEUS ACTIVITY IN THE NUCLEAR REGIONS OF THE INTERACTING GALAXY Arp 299

    SciTech Connect

    Alonso-Herrero, A.; Roche, P. F.; Esquej, P.; Colina, L.; González-Martín, O.; Ramos Almeida, C.; Asensio Ramos, A.; Rodríguez Espinosa, J. M.; Alvarez, C.; Pereira-Santaella, M.; Levenson, N. A.; Packham, C.; Mason, R. E.; Aretxaga, I.; Díaz-Santos, T.; Perlman, E.; Telesco, C. M.

    2013-12-10

    We present mid-infrared (MIR) 8-13 μm spectroscopy of the nuclear regions of the interacting galaxy Arp 299 (IC 694+NGC 3690) obtained with CanariCam (CC) on the 10.4 m Gran Telescopio Canarias (GTC). The high angular resolution (∼0.''3-0.''6) of the data allows us to probe nuclear physical scales between 60 and 120 pc, which is a factor of 10 improvement over previous MIR spectroscopic observations of this system. The GTC/CC spectroscopy displays evidence of deeply embedded active galactic nucleus (AGN) activity in both nuclei. The GTC/CC nuclear spectrum of NGC 3690/Arp 299-B1 can be explained as emission from AGN-heated dust in a clumpy torus with both a high covering factor and high extinction along the line of sight. The estimated bolometric luminosity of the AGN in NGC 3690 is 3.2 ± 0.6 × 10{sup 44} erg s{sup –1}. The nuclear GTC/CC spectrum of IC 694/Arp 299-A shows 11.3 μm polycyclic aromatic hydrocarbon emission stemming from a deeply embedded (A{sub V} ∼ 24 mag) region of less than 120 pc in size. There is also a continuum-emitting dust component. If associated with the putative AGN in IC 694, we estimate that it would be approximately five times less luminous than the AGN in NGC 3690. The presence of dual AGN activity makes Arp 299 a good example to study such phenomena in the early coalescence phase of interacting galaxies.

  13. THE ELECTRONIC STRUCTURE OF CeRhIn5 AND LaRhIn5 FROM ARPES.

    SciTech Connect

    D. P. MOORE; T. DURAKIEWICZ; ET AL

    2001-06-01

    In the heavy fermion CeRhIn{sub 5} and the isostructural compound LaRhIn{sub 5} the extra 4f electron in Ce dramatically alters the band structure near EF, suggesting that the 4f's participate in band formation. ARPES data indicates that correlation effects are mostly evident along the {Lambda}-Z direction in the Brillouin zone. Very good agreement to GGA band calculations is found.

  14. Molecular Gas Heating Mechanisms, and Star Formation Feedback in Merger/Starbursts: NGC 6240 and Arp 193 as Case Studies

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Padelis P.; Zhang, Zhi-Yu; Xilouris, E. M.; Weiss, Axel; van der Werf, Paul; Israel, F. P.; Greve, T. R.; Isaak, Kate G.; Gao, Y.

    2014-06-01

    We used the SPIRE/FTS instrument aboard the Herschel Space Observatory to obtain the Spectral Line Energy Distributions (SLEDs) of CO from J = 4-3 to J = 13-12 of Arp 193 and NGC 6240, two classical merger/starbursts selected from our molecular line survey of local Luminous Infrared Galaxies (L IR >= 1011 L ⊙). The high-J CO SLEDs are then combined with ground-based low-J CO, 13CO, HCN, HCO+, CS line data and used to probe the thermal and dynamical states of their large molecular gas reservoirs. We find the two CO SLEDs strongly diverging from J = 4-3 onward, with NGC 6240 having a much higher CO line excitation than Arp 193, despite their similar low-J CO SLEDs and L FIR/L CO, 1 - 0, L HCN/L CO (J = 1-0) ratios (proxies of star formation efficiency and dense gas mass fraction). In Arp 193, one of the three most extreme starbursts in the local universe, the molecular SLEDs indicate a small amount (~5%-15%) of dense gas (n >= 104 cm-3) unlike NGC 6240 where most of the molecular gas (~60%-70%) is dense (n ~ (104-105) cm-3). Strong star-formation feedback can drive this disparity in their dense gas mass fractions, and also induce extreme thermal and dynamical states for the molecular gas. In NGC 6240, and to a lesser degree in Arp 193, we find large molecular gas masses whose thermal states cannot be maintained by FUV photons from Photon-Dominated Regions. We argue that this may happen often in metal-rich merger/starbursts, strongly altering the initial conditions of star formation. ALMA can now directly probe these conditions across cosmic epoch, and even probe their deeply dust-enshrouded outcome, the stellar initial mass function averaged over galactic evolution.

  15. VizieR Online Data Catalog: Arp 220 6 and 33GHz images (Barcos-Munoz+, 2015)

    NASA Astrophysics Data System (ADS)

    Barcos-Munoz, L.; Leroy, A. K.; Evans, A. S.; Privon, G. C.; Armus, L.; Condon, J.; Mazzarella, J. M.; Meier, D. S.; Momjian, E.; Murphy, E. J.; Ott, J.; Reichardt, A.; Sakamoto, K.; Sanders, D. B.; Schinnerer, E.; Stierwalt, S.; Surace, J. A.; Thompson, T. A.; Walter, F.

    2016-07-01

    The FITS images show radio continuum emission towards Arp 220 as observed by the Karl G. Jansky Very Large Array. The two images are the "combined" ones, as described in Sect. 2 of the paper, where whe 6GHz image is obtained from the combined 4.7GHz and 7.2GHz data, and the 33GHz image is obtained from the combined 29GHz and 36GHz data. (2 data files).

  16. Broadening the Spectrum of Actin-Based Protrusive Activity Mediated by Arp2/3 Complex-Facilitated Polymerization: Motility of Cytoplasmic Ridges and Tubular Projections

    PubMed Central

    Henson, John H.; Gianakas, Anastasia D.; Henson, Lauren H.; Lakin, Christina L.; Voss, Meagen K.; Bewersdorf, Joerg; Oldenbourg, Rudolf; Morris, Robert L.

    2014-01-01

    Arp2/3 complex-facilitated actin polymerization plays an essential role in a variety of cellular functions including motility, adherence, endocytosis and trafficking. In the present study we employ the sea urchin coelomocyte experimental model system to test the hypotheses that Arp2/3 complex-nucleated actin assembly mediates the motility of two unusual cellular protrusions; the cytoplasmic ridges present during coelomocyte spreading, and inducible, tubular-shaped, and neurite-like projections. Our investigations couple pharmacological manipulation employing inhibitors of actin polymerization and the Arp2/3 complex with a wide array of imaging methods including digitally enhanced phase contrast, DIC and polarization light microscopy of live cells; conventional, confocal and super-resolution light microscopy of fluorescently labeled cells; and scanning and transmission electron microscopy. Taken together, the results of this study indicate that Arp2/3 complex-facilitated actin polymerization underlies the motility of coelomocyte cytoplasmic ridges and tubular projections, that these processes are related to each other, and that they have been preliminarily identified in other cell types. The results also highlight the broad spectrum of actin-based protrusive activities dependent on the Arp2/3 complex and provide additional insights into the pervasive nature of this ubiquitous actin nucleator. Furthermore we provide the first evidence of a possible mechanistic difference between the impacts of the small molecule drugs BDM and CK666 on the Arp2/3 complex. PMID:25111797

  17. Tolerance of ARPE 19 cells to organophosphorus pesticide chlorpyrifos is limited to concentration and time of exposure.

    PubMed

    Gomathy, Narayanan; Sumantran, Venil N; Shabna, A; Sulochana, K N

    2015-01-01

    Age related macular degeneration is a blinding disease common in elder adults. The prevalence of age related macular degeneration has been found to be 1.8% in the Indian population. Organophosphates are widely used insecticides with well documented neurological effects, and the persistent nature of these compounds in the body results in long term health effects. Farmers exposed to organophosphorus pesticides in USA had an earlier onset of age related macular degeneration when compared to unexposed controls. A recent study found significant levels of an organophosphate, termed chlorpyrifos, in the blood samples of Indian farmers. Therefore, in understanding the link between age related macular degeneration and chlorpyrifos, the need for investigation is important. Our data show that ARPE-19 (retinal pigment epithelial cells) exhibit a cytoprotective response to chlorpyrifos as measured by viability, mitochondrial membrane potential, superoxide dismutase activity, and increased levels of glutathione peroxidase and reduced glutathione, after 24 h exposure to chlorpyrifos. However, this cytoprotective response was absent in ARPE-19 cells exposed to the same range of concentrations of chlorpyrifos for 48 h. These results have physiological significance, since HPLC analysis showed that effects of chlorpyrifos were mediated through its entry into ARPE-19 cells. HPLC analysis also showed that chlorpyrifos remained stable, as we recovered up to 80% of the chlorpyrifos added to 6 different ocular tissues. PMID:25619908

  18. WASH complex regulates Arp2/3 complex for actin-based polar body extrusion in mouse oocytes

    PubMed Central

    Wang, Fei; Zhang, Liang; Zhang, Guang-Li; Wang, Zhen-Bo; Cui, Xiang-Shun; Kim, Nam-Hyung; Sun, Shao-Chen

    2014-01-01

    Prior to their fertilization, oocytes undergo asymmetric division, which is regulated by actin filaments. Recently, WASH complex were identified as actin nucleation promoting factors (NPF) that activated Arp2/3 complex. However, the roles of WASH complex remain uncertain, particularly for oocyte polarization and asymmetric division. Here, we examined the functions of two important subunits of a WASH complex, WASH1 and Strumpellin, during mouse oocyte meiosis. Depleting WASH1 or disrupting Strumpellin activity by WASH1 morpholino (MO) injection or Strumpellin antibody injection decreased polar body extrusion and caused oocyte symmetric division, and this may have been due to spindle formation and migration defects. Time lapse microscopy showed that actin filaments distribution and relative amount at the membrane and in the cytoplasm of oocytes was significantly decreased after disrupting WASH complex. In addition, Arp2/3 complex expression was reduced after WASH1 depletion. Thus, our data indicated that WASH complex regulated Arp2/3 complex and were required for cytokinesis and following polar body extrusion during mouse oocyte meiotic maturation. PMID:24998208

  19. Perinuclear Arp2/3-driven actin polymerization enables nuclear deformation to facilitate cell migration through complex environments

    PubMed Central

    Thiam, Hawa-Racine; Vargas, Pablo; Carpi, Nicolas; Crespo, Carolina Lage; Raab, Matthew; Terriac, Emmanuel; King, Megan C.; Jacobelli, Jordan; Alberts, Arthur S.; Stradal, Theresia; Lennon-Dumenil, Ana-Maria; Piel, Matthieu

    2016-01-01

    Cell migration has two opposite faces: although necessary for physiological processes such as immune responses, it can also have detrimental effects by enabling metastatic cells to invade new organs. In vivo, migration occurs in complex environments and often requires a high cellular deformability, a property limited by the cell nucleus. Here we show that dendritic cells, the sentinels of the immune system, possess a mechanism to pass through micrometric constrictions. This mechanism is based on a rapid Arp2/3-dependent actin nucleation around the nucleus that disrupts the nuclear lamina, the main structure limiting nuclear deformability. The cells' requirement for Arp2/3 to pass through constrictions can be relieved when nuclear stiffness is decreased by suppressing lamin A/C expression. We propose a new role for Arp2/3 in three-dimensional cell migration, allowing fast-moving cells such as leukocytes to rapidly and efficiently migrate through narrow gaps, a process probably important for their function. PMID:26975831

  20. Perinuclear Arp2/3-driven actin polymerization enables nuclear deformation to facilitate cell migration through complex environments.

    PubMed

    Thiam, Hawa-Racine; Vargas, Pablo; Carpi, Nicolas; Crespo, Carolina Lage; Raab, Matthew; Terriac, Emmanuel; King, Megan C; Jacobelli, Jordan; Alberts, Arthur S; Stradal, Theresia; Lennon-Dumenil, Ana-Maria; Piel, Matthieu

    2016-01-01

    Cell migration has two opposite faces: although necessary for physiological processes such as immune responses, it can also have detrimental effects by enabling metastatic cells to invade new organs. In vivo, migration occurs in complex environments and often requires a high cellular deformability, a property limited by the cell nucleus. Here we show that dendritic cells, the sentinels of the immune system, possess a mechanism to pass through micrometric constrictions. This mechanism is based on a rapid Arp2/3-dependent actin nucleation around the nucleus that disrupts the nuclear lamina, the main structure limiting nuclear deformability. The cells' requirement for Arp2/3 to pass through constrictions can be relieved when nuclear stiffness is decreased by suppressing lamin A/C expression. We propose a new role for Arp2/3 in three-dimensional cell migration, allowing fast-moving cells such as leukocytes to rapidly and efficiently migrate through narrow gaps, a process probably important for their function. PMID:26975831

  1. Probing the magnetic field of the nearby galaxy pair Arp 269

    NASA Astrophysics Data System (ADS)

    Nikiel-Wroczyński, B.; Jamrozy, M.; Soida, M.; Urbanik, M.; Knapik, J.

    2016-06-01

    We present a multiwavelength radio study of the nearby galaxy pair Arp 269 (NGC 4490/85). High sensitivity to extended structures gained by using the merged interferometric and single-dish maps allowed us to reveal a previously undiscovered extension of the radio continuum emission. Its direction is significantly different from that of the neutral gas tail, suggesting that different physical processes might be involved in their creation. The population of radio-emitting electrons is generally young, signifying an ongoing, vigorous star formation - this claim is supported by strong magnetic fields (over 20 μG), similar to the ones found in much larger spiral galaxies. From the study of the spectral energy distribution, we conclude that the electron population in the intergalactic bridge between member galaxies originates from the disc areas, and therefore its age (approximately 3.7-16.9 Myr, depending on the model used) reflects the time-scale of the interaction. We have also discovered an angularly near compact steep source - which is a member of a different galaxy pair - at a redshift of approximately 0.125.

  2. DECONTAMINATION FACTORS AND FILTRATION FLUX IMPACT TO ARP AT REDUCED MST CONCENTRATION

    SciTech Connect

    Hobbs, D.

    2012-06-27

    Tank Farm and Closure Engineering is evaluating changes to the Actinide Removal Process facility operations to decrease the MST concentration from 0.4 g/L to 0.2 g/L and the contact time from 12 hours to between 6 and 8 hours. For this evaluation, SRNL reviewed previous datasets investigating the performance of MST at 0.2 g/L in salt solutions ranging from 4.5 to 7.5 M in sodium concentration. In general, reducing the MST concentration from 0.4 to 0.2 g/L and increasing the ionic strength from 4.5 to 7.5 M in sodium concentration will decrease the measured decontamination factors for plutonium, neptunium, uranium and strontium. The decontamination factors as well as single standard deviation values for each sorbate are reported. These values are applicable within the sorbate and sodium concentrations used in the experimental measurements. Decreasing the MST concentration in the ARP from 0.4 g/L to 0.2 g/L will produce an increase in the filter flux, and could lead to longer operating times between filter cleaning. The increase in flux is a function of a number of operating parameters, and is difficult to quantify. However, it is estimated that the reduction in MST could result in a reduction of filtration time of up to 20%.

  3. Band parameters of 2D semiconductor heterostructures determined by micro-ARPES

    NASA Astrophysics Data System (ADS)

    Nguyen, Paul; Wilson, Neil; Rivera, Pasqual; Seyler, Kyle; Barinov, Alexey; Balakrishnan, Geetha; Xu, Xiaodong; Cobden, David

    Heterostructures made by stacking monolayers of different 2D materials can have unique properties, such as hosting long-lived polarized interlayer excitons. Understanding these depends on knowledge of the band parameters of both the separate monolayers and the hetero-bilayer. Interlayer hybridization can also produce distinct electronic structure dependent on the relative monolayer crystal orientation. The most powerful technique for determining such properties is angle-resolved photoemission (ARPES), which can now be applied to micron-scale samples at the Spectromicroscopy Elettra Trieste beamline. Using this new facility, combined with careful sample design, we have studied heterostructures of WSe2, MoSe2, WS2 and graphene. We determined band offsets, effective masses, and spin-orbit splittings with an energy resolution <50 meV. Interestingly, the bands near the gamma-point in hetero-bilayers oriented near zero degrees are not a superposition of those in the isolated monolayers, but exhibit an additional higher band. However, the valence band edge remains at the K-point, which together with the band offsets is consistent with measurements of strong luminescence from interlayer excitons in MoSe2/WSe2.

  4. THE MASS OF THE BLACK HOLE IN Arp 151 FROM BAYESIAN MODELING OF REVERBERATION MAPPING DATA

    SciTech Connect

    Brewer, Brendon J.; Treu, Tommaso; Pancoast, Anna; Bennert, Vardha N.; Barth, Aaron J.; Bentz, Misty C.; Filippenko, Alexei V.; Greene, Jenny E.; Malkan, Matthew A.; Woo, Jong-Hak

    2011-06-01

    Supermassive black holes are believed to be ubiquitous at the centers of galaxies. Measuring their masses is extremely challenging yet essential for understanding their role in the formation and evolution of cosmic structure. We present a direct measurement of the mass of a black hole in an active galactic nucleus (Arp 151) based on the motion of the gas responsible for the broad emission lines. By analyzing and modeling spectroscopic and photometric time series, we find that the gas is well described by a disk or torus with an average radius of 3.99 {+-} 1.25 light days and an opening angle of 68.9{sup +21.4}{sub -17.2} deg, viewed at an inclination angle of 67.8 {+-} 7.8 deg (that is, closer to face-on than edge-on). The black hole mass is inferred to be 10{sup 6.51{+-}0.28} M{sub sun}. The method is fully general and can be used to determine the masses of black holes at arbitrary distances, enabling studies of their evolution over cosmic time.

  5. Star formation on the leading edge of a ring-like density wave in Arp 143

    NASA Technical Reports Server (NTRS)

    Appleton, P. N.

    1990-01-01

    NGC 2445 is a member of the pair of interacting galaxies Arp 143 (=VV117) and has been classified as an irregular ring galaxy by deVaucouleurs et al. (1976). Although not obviously a classical ring galaxy from its optical appearance, it nevertheless shows many of the symptoms of a collisional off-center ring galaxy in the early stages of development. Optically the galaxy shows a rough ring of super-giant HII regions distributed asymmetrically with respect to the nucleus with most of the emission concentrated on the western side of the galaxy. Researchers mapped the HI emission in this system (with F. Ghigo and J. van Gorkom; NRAO) and the observations show that the disk of NGC 2445 is characterized by a large-scale banana-shaped HI wave with its peak to the west of the nucleus. Nearing-IR imaging (with E. I. Robson and A. J. Adamson; Lancs. Polytechnic, U.K.) demonstrates that, like the HI, the underlying population of old stars is very asymmetrically distributed with the bulk of the stars concentrated to the western side of the galaxy.

  6. High binding energy band structure of Bi-2212 as measured by ARPES

    NASA Astrophysics Data System (ADS)

    McElroy, K.; Graf, J.; Gweon, G.-H.; Zhou, S. Y.; Sahrakorpi, S.; Lindroos, M.; Markiewicz, R. S.; Bansil, A.; Eisaki, H.; Sasagawa, T.; Takagi, H.; Uchida, S.; Lanzara, A.

    2006-03-01

    The study of the electronic structure of high temperature superconductors by angle resolved photoemission spectroscopy (ARPES) has so far focused on the states near the Fermi level, believed to be fundamental for most of the properties of cuprates. However, it is well known that in doped Mott insulators the low and high energy physics are strongly coupled one to the other. Therefore, to gain insight on the real physics of cuprates a full characterization of the electronic band structure up to energies of the order of the lower Hubbard band and beyond is needed. Here we report a detailed, doping dependent study of the band structure of Bi2212 superconductors at energies of the order of 1-2 eV. The experimental results are interpreted in terms of local density approximation (LDA) based computations, where the presence of the ``spaghetti'' of Cu-O and O-bands is predicted. Comparison between computed and measured bands provides insight into many-body renormalization effects.

  7. Local Data Integration in East Central Florida Using the ARPS Data Analysis System

    NASA Technical Reports Server (NTRS)

    Case, Jonathan; Manobianco, John

    1998-01-01

    This paper describes the Applied Meteorology Unit's (AMU) efforts to configure, implement, and test a version of the Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS; Brewster 1996) that assimilates all available data within 250 km of the Kennedy Space Center (KSC) and the Eastern Range at Cape Canaveral Air Station (CCAS). The objective for running a Local Data Integration System (LDIS) such as ADAS is to generate products which may enhance weather nowcasts and short-range (less than 6 h) forecasts issued in support of ground and aerospace operations at KSC/CCAS. A LDIS such as ADAS has the potential to provide added value because it combines observational data to produce gridded analyses of temperature, wind, and moisture (including clouds) and diagnostic quantities such as vorticity, divergence, etc. at specified temporal and spatial resolutions. In this regard, a LDTS along with suitable visualization tools may provide users with a ignore complete and comprehensive understanding of evolving weather than could be developed by individually examining the disparate data sets over the same area and time. The AMU implemented a working prototype of the ADAS which does not run in real-time. Instead, the AMU is evaluating ADAS through post-analyses of weather events for a warm and cool season case. The case studies were chosen to investigate the capabilities and limitations of a LDIS such as ADAS including the impact of non-incorporation of specific data sources on the utility of the subsequent analyses.

  8. Long-term Failure Prediction based on an ARP Model of Global Risk Network

    NASA Astrophysics Data System (ADS)

    Lin, Xin; Moussawi, Alaa; Szymanski, Boleslaw; Korniss, Gyorgy

    Risks that threaten modern societies form an intricately interconnected network. Hence, it is important to understand how risk materializations in distinct domains influence each other. In the paper, we study the global risks network defined by World Economic Forum experts in the form of Stochastic Block Model. We model risks as Alternating Renewal Processes with variable intensities driven by hidden values of exogenous and endogenous failure probabilities. Based on the expert assessments and historical status of each risk, we use Maximum Likelihood Evaluation to find the optimal model parameters and demonstrate that the model considering network effects significantly outperforms the others. In the talk, we discuss how the model can be used to provide quantitative means for measuring interdependencies and materialization of risks in the network. We also present recent results of long-term predictions in the form of predicated distributions of materializations over various time periods. Finally we show how the simulation of ARP's enables us to probe limits of the predictability of the system parameters from historical data and ability to recover hidden variable. Supported in part by DTRA, ARL NS-CTA.

  9. Tank 49H salt batch supernate qualification for ARP/MCU

    SciTech Connect

    Nash, C. A.; Peters, T.; Fink, S.; Foster, T.

    2008-08-25

    This report covers the laboratory testing and analyses of Tank 49H Qualification Sample Sets A and C, performed in support of initial radioactive operations of Actinide Removal Process (ARP) and Modular Caustic-Side Solvent Extraction Unit (MCU). Major goals of this work include checking that Tank 49H was well mixed after the last receipt of Tank 23H, characterizing Tank 49H supernate after solids are settled so that its composition can be compared to waste acceptance and hazard criteria, verifying actinide and strontium adsorption with a small scale test using monosodium titanate (MST) and filtration, checking MCU solvent performance when applied to the liquid produced from MST contact, and verifying that in-tank settling after a minimum of 30 days was at least as good or better at reducing solids content after a Tank 49H to Tank 50H transfer occurred than what was observed in less time in the lab. The first four items were covered by Sample Set A. The fifth item was covered by Sample Set C, which had several analyses after compositing as required in the nuclear criticality safety evaluation (NCSE).

  10. The zinc ionophore clioquinol reverses autophagy arrest in chloroquine-treated ARPE-19 cells and in APP/mutant presenilin-1-transfected Chinese hamster ovary cells.

    PubMed

    Seo, Bo-Ra; Lee, Sook-Jeong; Cho, Kyung Sook; Yoon, Young Hee; Koh, Jae-Young

    2015-12-01

    Arrested autophagy may contribute to the pathogenesis of Alzheimer's disease. Because we found that chloroquine (CQ) causes arrested autophagy but clioquinol (ClioQ), a zinc ionophore, activates autophagic flux, in the present study, we examined whether ClioQ can overcome arrested autophagy induced by CQ or mutant presenilin-1 (mPS1). CQ induced vacuole formation and cell death in adult retinal pigment epithelial (ARPE-19) cells, but co-treatment with ClioQ attenuated CQ-associated toxicity in a zinc-dependent manner. Increases in lysosome dilation and blockage of autophagic flux by CQ were also markedly attenuated by ClioQ treatment. Interestingly, CQ increased lysosomal pH in amyloid precursor protein (APP)/mPS1-expressing Chinese hamster ovary 7WΔE9 (CHO-7WΔE9) cell line, and ClioQ partially re-acidified lysosomes. Furthermore, accumulation of amyloid-β (Aβ) oligomers in CHO-7WΔE9 cells was markedly attenuated by ClioQ. Moreover, intracellular accumulation of exogenously applied fluorescein isothiocyanate-conjugated Aβ(1-42) was also increased by CQ but was returned to control levels by ClioQ. These results suggest that modulation of lysosomal functions by manipulating lysosomal zinc levels may be a useful strategy for clearing intracellular Aβ oligomers. PMID:26453000

  11. Paxillin, a novel controller in the signaling of estrogen to FAK/N-WASP/Arp2/3 complex in breast cancer cells.

    PubMed

    Shortrede, Jorge Eduardo; Uzair, Ivonne Denise; Neira, Flavia Judith; Flamini, Marina Inés; Sanchez, Angel Matías

    2016-07-15

    Breast cancer is the major cause of cancer-related death in women. Its treatment is particularly difficult when metastasis occurs. The ability of cancer cells to move and invade the surrounding environment is the basis of local and distant metastasis. Cancer cells are able to remodel the actin cytoskeleton, which requires the recruitment of numerous structural and regulatory proteins that modulate actin filaments dynamics, including Paxillin or the Neural Wiskott-Aldrich Syndrome Protein (N-WASP). We show that 17-β estradiol (E2) induces phosphorylation of Paxillin and its translocation toward membrane sites where focal adhesion complexes are assembled. This cascade is triggered by a Gαi1/Gβ protein-dependent signaling of estrogen receptor α (ERα) to c-Src, focal adhesion kinase (FAK) and Paxillin. Within this complex, activated Paxillin recruits the small GTPase Cdc42, which triggers N-WASP phosphorylation. This results in the redistribution of Arp2/3 complexes at sites where membrane structures related to cell movement are formed. Recruitment of Paxillin, Cdc42 and N-WASP is necessary for cell adhesion, migration and invasion induced by E2 in breast cancer cells. In parallel, we investigated whether Raloxifene (RAL), a selective estrogen receptor modulator (SERMs), could inhibit or revert the effects of E2 in breast cancer cell movement. We found that, in the presence of E2, RAL acts as an ER antagonist and displays an inhibitory effect on estrogen-promoted cell adhesion and migration via FAK/Paxillin/N-WASP. Our findings identify an original mechanism through which estrogen regulates breast cancer cell motility and invasion via Paxillin. These results may have clinical relevance for the development of new therapeutic strategies for cancer treatment. PMID:27095481

  12. HIGH-RESOLUTION RADIO CONTINUUM MEASUREMENTS OF THE NUCLEAR DISKS OF Arp 220

    SciTech Connect

    Barcos-Muñoz, L.; Evans, A. S.; Privon, G. C.; Stierwalt, S.; Leroy, A. K.; Condon, J.; Reichardt, A.; Armus, L.; Mazzarella, J. M.; Murphy, E. J.; Meier, D. S.; Momjian, E.; Ott, J.; Sakamoto, K.; Sanders, D. B.; Schinnerer, E.; Walter, F.; Surace, J. A.; Thompson, T. A.

    2015-01-20

    We present new Karl G. Jansky Very Large Array radio continuum images of the nuclei of Arp 220, the nearest ultra-luminous infrared galaxy. These new images have both the angular resolution to study the detailed morphologies of the two nuclei that power the galaxy merger and sensitivity to a wide range of spatial scales. At 33 GHz, we achieve a resolution of 0.''081 × 0.''063 (29.9 × 23.3 pc) and resolve the radio emission surrounding both nuclei. We conclude from the decomposition of the radio spectral energy distribution that a majority of the 33 GHz emission is synchrotron radiation. The spatial distributions of radio emission in both nuclei are well described by exponential profiles. These have deconvolved half-light radii (R {sub 50d}) of 51 and 35 pc for the eastern and western nuclei, respectively, and they match the number density profile of radio supernovae observed with very long baseline interferometry. This similarity might be due to the fast cooling of cosmic rays electrons caused by the presence of a strong (∼mG) magnetic field in this system. We estimate extremely high molecular gas surface densities of 2.2{sub −1.0}{sup +2.1}×10{sup 5} (east) and 4.5{sub −1.9}{sup +4.5}×10{sup 5} (west) M {sub ☉} pc{sup –2}, corresponding to total hydrogen column densities of N {sub H} = 2.7{sub −1.2}{sup +2.7}×10{sup 25} (east) and 5.6{sub −2.4}{sup +5.5}×10{sup 25} cm{sup –2} (west). The implied gas volume densities are similarly high, n{sub H{sub {sub 2}}}∼3.8{sub −1.6}{sup +3.8}×10{sup 4} (east) and ∼11{sub −4.5}{sup +12}×10{sup 4} cm{sup –3} (west). We also estimate very high luminosity surface densities of Σ{sub IR}∼4.2{sub −0.7}{sup +1.6}×10{sup 13} (east) and Σ{sub IR}∼9.7{sub −2.4}{sup +3.7}×10{sup 13} (west) L{sub ⊙} kpc{sup −2}, and star formation rate surface densities of Σ{sub SFR} ∼ 10{sup 3.7} {sup ±} {sup 0.1} (east) and Σ{sub SFR} ∼ 10{sup 4.1} {sup ±} {sup 0.1}(west) M {sub ☉} yr{sup

  13. Inhibition of phagocytic activity of ARPE-19 cells by free radical mediated oxidative stress.

    PubMed

    Olchawa, Magdalena M; Pilat, Anna K; Szewczyk, Grzegorz M; Sarna, Tadeusz Jan

    2016-08-01

    Oxidative stress is a main factor responsible for key changes leading to the onset of age-related macular degeneration (ARMD) that occur in the retinal pigment epithelium (RPE), which is involved in phagocytosis of photoreceptor outer segments (POS). In this study, hydrogen peroxide (H2O2), H2O2 and iron ions (Fe) or rose Bengal (RB) in the presence of NADH and Fe were used to model free radical mediated oxidative stress to test if free radicals and singlet oxygen have different efficiency to inhibit phagocytosis of ARPE-19 cells. Free radical mediated oxidative stress was confirmed by HPLC-EC(Hg) measurements of cholesterol hydroperoxides in treated cells. Electron paramagnetic resonance (EPR) spin trapping was employed to detect superoxide anion. Cell survival was analyzed by the MTT assay. Specific phagocytosis of fluorescein-5-isothiocyanate-labeled POS and non-specific phagocytosis of fluorescent beads were measured by flow cytometry. HPLC analysis of cells photosensitized with RB in the presence of NADH and Fe indicated substantial increase in formation of free radical-dependent 7α/7β-hydroperoxides. EPR spin trapping confirmed the photogeneration of superoxide anion in samples enriched with RB, NADH and Fe. For all three protocols sub-lethal oxidative stress induced significant inhibition of the specific phagocytosis of POS. In contrast, non-specific phagocytosis was inhibited only by H2O2 or H2O2 and Fe treatment. Inhibition of phagocytosis was transient and recoverable by 24 h. These results suggest that free radicals may exert similar to singlet oxygen efficiency in inhibiting phagocytosis of RPE cells, and that the effect depends on the location where initial reactive species are formed. PMID:27225587

  14. ARPES Study on the Strongly Correlated Iron Chalcogenides Fe1+ySexTe1-x

    NASA Astrophysics Data System (ADS)

    Liu, Zhongkai

    2014-03-01

    The level of electronic correlation has been one of the key questions in understanding the nature of iron-based superconductivity. Using Angle Resolved Photoemission Spectroscopy (ARPES), we systematically investigated the correlation level in the iron chalcogenide family Fe1+ySexTe1-x. For the parent compound Fe1.02Te, we discovered ``peak-dip-hump'' spectra with heavily renormalized quasiparticles in the low temperature antiferromagnetic (AFM) state, characteristic of coherent polarons seen in other correlated materials with complex electronic and lattice interactions. As the temperature (or Se ratio x) increases and Fe1.02SexTe1-x is in the paramagnetic (PM) phase, we observed dissociation behavior of polarons, suggestive of connection between the weakening electron-phonon coupling and AFM. Further increase of x leads to an incoherent to coherent crossover in the electronic structure, indicating a reduction in the electronic correlation as the superconductivity emerges. Furthermore, the reduction of the electronic correlation in Fe1+ySexTe1-x evolves in an orbital-dependent way, where the dxy orbital is influenced most significantly. At the other end of the phase diagram (FeSe) where the single crystal is not stable, we have studied the MBE-grown thin film which also reveals orbital-dependent strong correlation in the electronic structure. Our findings provide a quantitative comprehension on the correlation level and its evolution on the phase diagram of Fe1+ySexTe1-x. We discuss the physical scenarios leading to strong correlations and its connection to superconductivity.

  15. Afatinib Reduces STAT6 Signaling of Host ARPE-19 Cells Infected with Toxoplasma gondii

    PubMed Central

    Yang, Zhaoshou; Ahn, Hye-Jin; Park, Young-Hoon; Nam, Ho-Woo

    2016-01-01

    Specific gene expressions of host cells by spontaneous STAT6 phosphorylation are major strategy for the survival of intracellular Toxoplasma gondii against parasiticidal events through STAT1 phosphorylation by infection provoked IFN-γ. We determined the effects of small molecules of tyrosine kinase inhibitors (TKIs) on the growth of T. gondii and on the relationship with STAT1 and STAT6 phosphorylation in ARPE-19 cells. We counted the number of T. gondii RH tachyzoites per parasitophorous vacuolar membrane (PVM) after treatment with TKIs at 12-hr intervals for 72 hr. The change of STAT6 phosphorylation was assessed via western blot and immunofluorescence assay. Among the tested TKIs, Afatinib (pan ErbB/EGFR inhibitor, 5 µM) inhibited 98.0% of the growth of T. gondii, which was comparable to pyrimethamine (5 µM) at 96.9% and followed by Erlotinib (ErbB1/EGFR inhibitor, 20 µM) at 33.8% and Sunitinib (PDGFR or c-Kit inhibitor, 10 µM) at 21.3%. In the early stage of the infection (2, 4, and 8 hr after T. gondii challenge), Afatinib inhibited the phosphorylation of STAT6 in western blot and immunofluorescence assay. Both JAK1 and JAK3, the upper hierarchical kinases of cytokine signaling, were strongly phosphorylated at 2 hr and then disappeared entirely after 4 hr. Some TKIs, especially the EGFR inhibitors, might play an important role in the inhibition of intracellular replication of T. gondii through the inhibition of the direct phosphorylation of STAT6 by T. gondii. PMID:26951976

  16. Arp2/3 complex is critical for lamellipodia and organization of cell-matrix adhesion but dispensable for fibroblast chemotaxis

    PubMed Central

    Wu, Congying; Asokan, Sreeja B.; Berginski, Matthew E.; Haynes, Elizabeth M.; Sharpless, Norman E.; Griffith, Jack D.; Gomez, Shawn M.; Bear, James E.

    2012-01-01

    SUMMARY Lamellipodia are sheet-like, leading edge protrusions in firmly adherent cells that contain Arp2/3-generated dendritic actin networks. Although lamellipodia are widely believed to be critical for directional cell motility, this notion has not been rigorously tested. Using fibroblasts derived from Ink4a/Arf-deficient mice, we generated a stable line depleted of Arp2/3 complex that lacks lamellipodia. This line shows defective random cell motility and relies on a filopodia-based protrusion system. Utilizing a microfluidic gradient generation system, we tested the role of Arp2/3 complex and lamellipodia in directional cell migration. Surprisingly, Arp2/3-depleted cells respond normally to shallow gradients of PDGF indicating that lamellipodia are not required for fibroblast chemotaxis. Conversely, these cells cannot respond to a surface-bound gradient of extracellular matrix (haptotaxis). Consistent with this finding, cells depleted of Arp2/3 fail to globally align focal adhesions suggesting that one principle function of lamellipodia is to organize cell-matrix adhesions in a spatially coherent manner. PMID:22385962

  17. CO J = 6-5 IN Arp 220: STRONG EFFECTS OF DUST ON HIGH-J CO LINES

    SciTech Connect

    Papadopoulos, Padeli P.; Isaak, Kate; Van der Werf, Paul E-mail: Kate.Isaak@astro.cf.ac.u

    2010-03-10

    We report new single dish CO J = 6-5 line observations for the archetypal Ultra Luminous Infrared Galaxy (ULIRG) Arp 220 with the James Clerk Maxwell Telescope atop Mauna Kea in Hawaii. The J = 6-5 line is found to be faint, with brightness temperature ratios (6-5)/(1-0), (6-5)/(3-2) of R{sub 65/10} = 0.080 +- 0.017 and R{sub 65/32} = 0.082 +- 0.019, suggesting very low excitation conditions that cannot be reconciled with the warm and very dense molecular gas present in one of the most extreme starbursts in the local universe. We find that an optically thick dust continuum, with tau(nu {approx}> 350 GHz) {approx}> 1 for the bulk of the warm dust and gas in Arp 220, submerges this line to an almost black body curve, reducing its flux, and affecting its CO spectral line energy distribution at high frequencies. This also resolves the C{sup +} line deficiency in this object, first observed by Infrared Space Observatory: the near absence of that line is a dust optical depth effect, not a dense photodissociation region phenomenon. Finally, we briefly comment on the possibility of such extreme interstellar medium (ISM) states in other ULIRGs in the distant universe, and their consequences for the diagnostic utility of high frequency molecular and atomic ISM lines in such systems. In the case of Arp 220, we anticipate that the now spaceborne Herschel Space Observatory will find faint high-J CO lines at nu {approx}> 690 GHz that would appear as sub-thermally excited with respect to the low-J ones as a result of the effects of dust absorption.

  18. ARPES lineshapes, coherent to incoherent ratios, and the waterfall self-energy of Bi2212 cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; Sun, Zhe; Das, Tanmoy; Balatsky, Alexander; Rotenberg, Eli; Berger, Helmuth; Eisaki, Hiroshi; Aiura, Yoshihiro; Dessau, Daniel

    2011-03-01

    We report a detailed lineshape analysis of ARPES data on Bi2212 in which we separate out the sharp coherent peaks from the higher energy incoherent ``background'' portions, which includes and makes up the famous waterfall regions. We find that the ratio of the incoherent to coherent weights scales quadratically with the peak energy of the coherent portion of the spectra over a very wide energy range. We show that this behavior, including the waterfalls, can be understood with a simple model electron self-energy, giving a new and powerful experimental tool for determining self-energy effects in correlated electron systems.

  19. Molecular gas heating mechanisms, and star formation feedback in merger/starbursts: NGC 6240 and Arp 193 as case studies

    SciTech Connect

    Papadopoulos, Padelis P.; Zhang, Zhi-Yu; Weiss, Axel; Van der Werf, Paul; Israel, F. P.; Greve, T. R.; Isaak, Kate G.; Gao, Y. E-mail: zyzhang@pmo.ac.cn E-mail: aweiss@mpifr-bonn.mpg.de E-mail: israel@strw.leidenuniv.nl E-mail: kisaak@rssd.esa.int

    2014-06-20

    We used the SPIRE/FTS instrument aboard the Herschel Space Observatory to obtain the Spectral Line Energy Distributions (SLEDs) of CO from J = 4-3 to J = 13-12 of Arp 193 and NGC 6240, two classical merger/starbursts selected from our molecular line survey of local Luminous Infrared Galaxies (L {sub IR} ≥ 10{sup 11} L {sub ☉}). The high-J CO SLEDs are then combined with ground-based low-J CO, {sup 13}CO, HCN, HCO{sup +}, CS line data and used to probe the thermal and dynamical states of their large molecular gas reservoirs. We find the two CO SLEDs strongly diverging from J = 4-3 onward, with NGC 6240 having a much higher CO line excitation than Arp 193, despite their similar low-J CO SLEDs and L {sub FIR}/L {sub CO,} {sub 1} {sub –0}, L {sub HCN}/L {sub CO} (J = 1-0) ratios (proxies of star formation efficiency and dense gas mass fraction). In Arp 193, one of the three most extreme starbursts in the local universe, the molecular SLEDs indicate a small amount (∼5%-15%) of dense gas (n ≥ 10{sup 4} cm{sup –3}) unlike NGC 6240 where most of the molecular gas (∼60%-70%) is dense (n ∼ (10{sup 4}-10{sup 5}) cm{sup –3}). Strong star-formation feedback can drive this disparity in their dense gas mass fractions, and also induce extreme thermal and dynamical states for the molecular gas. In NGC 6240, and to a lesser degree in Arp 193, we find large molecular gas masses whose thermal states cannot be maintained by FUV photons from Photon-Dominated Regions. We argue that this may happen often in metal-rich merger/starbursts, strongly altering the initial conditions of star formation. ALMA can now directly probe these conditions across cosmic epoch, and even probe their deeply dust-enshrouded outcome, the stellar initial mass function averaged over galactic evolution.

  20. ARP: Automatic rapid processing for the generation of problem dependent SAS2H/ORIGEN-s cross section libraries

    SciTech Connect

    Leal, L.C.; Hermann, O.W.; Bowman, S.M.; Parks, C.V.

    1998-04-01

    In this report, a methodology is described which serves as an alternative to the SAS2H path of the SCALE system to generate cross sections for point-depletion calculations with the ORIGEN-S code. ARP, Automatic Rapid Processing, is an algorithm that allows the generation of cross-section libraries suitable to the ORIGEN-S code by interpolation over pregenerated SAS2H libraries. The interpolations are carried out on the following variables: burnup, enrichment, and water density. The adequacy of the methodology is evaluated by comparing measured and computed spent fuel isotopic compositions for PWR and BWR systems.

  1. Evidence of reduced surface electron-phonon scattering in the conduction band of Bi2Se3 by nonequilibrium ARPES

    NASA Astrophysics Data System (ADS)

    Crepaldi, A.; Cilento, F.; Ressel, B.; Cacho, C.; Johannsen, J. C.; Zacchigna, M.; Berger, H.; Bugnon, Ph.; Grazioli, C.; Turcu, I. C. E.; Springate, E.; Kern, K.; Grioni, M.; Parmigiani, F.

    2013-09-01

    The nature of the Dirac quasiparticles in topological insulators calls for a direct investigation of the electron-phonon scattering at the surface. By comparing time-resolved ARPES measurements of the topological insulator Bi2Se3 with different probing depths, we show that the relaxation dynamics of the electronic temperature of the conduction band is much slower at the surface than in the bulk. This observation suggests that surface phonons are less effective in cooling the electron gas in the conduction band.

  2. Structural and electronic changes in the growth of mercury overlayers on Cu(001) - A helium beam scattering, LEED and ARPES study

    NASA Technical Reports Server (NTRS)

    Vidali, G.; Li, W.; Dowben, P. A.; Karimi, M.; Hutchings, C. W.; Lin, J.; Moses, C.; Ila, D.; Dalins, I.

    1990-01-01

    We used ABS, LEED and angle-resolved photo-electron spectroscopy (ARPES) to study bilayer films of Hg on Cu(001). In the surface temperature range of 180 to 330 K, the first Hg layer forms two ordered phases, a c(2x2) (with coverage-0.5 of Cu(001)) and a high density (partially commensurate) c(4x4) (coverage-0.62). ARPES data show that there is little or no dispersion of the 5d band of Hg. ABS data show that this layer is not flat, with in-registry Hg atoms lying about 0.15 below the not-in-registry Hg atoms. From ABS we find that the second layer forms a completely registered c(4x4) phase. From ARPES we obtain that the second layer has an electronic structure, particularly the 5d levels, characteristic of bulk mercury. Preliminary results of calculations of the structure of the bilayer are given.

  3. Isolation of a Novel Family of C2H2 Zinc Finger Proteins Implicated in Transcriptional Repression Mediated by Chicken Ovalbumin Upstream Promoter Transcription Factor (COUP-TF) Orphan Nuclear Receptors*

    PubMed Central

    Avram, Dorina; Fields, Andrew; Top, Karen Pretty On; Nevrivy, Daniel J.; Ishmael, Jane E.; Leid, Mark

    2010-01-01

    Two novel and related C2H2 zinc finger proteins that are highly expressed in the brain, CTIP1 and CTIP2 (COUP TF-interacting proteins 1 and 2, respectively), were isolated and shown to interact with all members of the chicken ovalbumin upstream promoter transcription factor (COUP-TF) subfamily of orphan nuclear receptors. The interaction of CTIP1 with ARP1 was studied in detail, and CTIP1 was found to harbor two independent ARP1 interaction domains, ID1 and ID2, whereas the putative AF-2 of ARP1 was required for interaction with CTIP1. CTIP1, which exhibited a punctate staining pattern within the nucleus of transfected cells, recruited cotransfected ARP1 to these foci and potentiated ARP1-mediated transcriptional repression of a reporter construct. However, transcriptional repression mediated by ARP1 acting through CTIP1 did not appear to involve recruitment of a trichostatin A-sensitive histone deacetylase(s) to the template, suggesting that this repression pathway may be distinct from that utilized by several other nuclear receptors. PMID:10744719

  4. ARPES study of the surface states from Au/Ag( 1 1 1 ): evolution with coverage and photon energy

    NASA Astrophysics Data System (ADS)

    Palomares, F. J.; Serrano, M.; Ruiz, A.; Soria, F.; Horn, K.; Alonso, M.

    2002-07-01

    The Shockley surface states formed on the (1 1 1) surfaces of noble metals have been extensively studied, but few reports exist on layered thin film systems. We present angle-resolved photoemission (ARPES) results, recorded at normal emission in the photon energy range from 21 to 49 eV, which describe the behavior of these sp-derived surface states for Au layers epitaxially grown on Ag(1 1 1). Growth was performed at room and low temperatures. In both cases, the ARPES spectra are found to evolve from Ag(1 1 1)-like to Au(1 1 1)-like features as the thickness of the Au film increases. In particular, the surface-state binding energy shifts from the Ag(1 1 1) to the bulk Au(1 1 1) position, the shift being already evident at coverages lower than one monolayer. The origin of the changes observed in the surface-state peak as a function of Au coverage and photon energy will be discussed.

  5. XPS and ARPES study of the metal-insulator transition in Mn-substituted Sr3Ru2O7

    NASA Astrophysics Data System (ADS)

    Zhu, Zhihuai; Levy de Castro, G.; Hossain, M. A.; Manju, U.; McCheyney, J. L.; Bostwick, A.; Rotenberg, E.; Yoshida, Y.; Elfimov, I. S.; Panaccione, G.; Damascelli, A.

    2010-03-01

    We have studied the metal-insulator transition in Mn-substituted Sr3Ru2O7 by core-level x-ray photoemission (XPS) and angle-resolved photoemission spectroscopy (ARPES). In XPS, both the surface- and bulk-sensitive spectra show a two-peak structure, corresponding to the well screened and the unscreened excitations. The intensity of the well-screened peak is suppressed upon increasing the concentration of Mn, reflecting a metal-to-insulator transition induced by Mn impurities. In ARPES, changes in Fermi surface topology and band dispersions are observed as the system crosses over from a metal to a - possibly Mott - insulator. We observed a variation and enhancement of the Fermi-surface nesting upon Mn substitution, which might be connected to the emergence of the magnetic superstructure revealed by our resonant elastic soft x-ray scattering results [1].[4pt] [1] M.A. Hossain et al., arXiv:0906.0035 (2009).

  6. Protein

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Proteins are the major structural and functional components of all cells in the body. They are macromolecules that comprise 1 or more chains of amino acids that vary in their sequence and length and are folded into specific 3-dimensional structures. The sizes and conformations of proteins, therefor...

  7. Proteins.

    ERIC Educational Resources Information Center

    Doolittle, Russell F.

    1985-01-01

    Examines proteins which give rise to structure and, by virtue of selective binding to other molecules, make genes. Binding sites, amino acids, protein evolution, and molecular paleontology are discussed. Work with encoding segments of deoxyribonucleic acid (exons) and noncoding stretches (introns) provides new information for hypotheses. (DH)

  8. Spin-Label CW Microwave Power Saturation and Rapid Passage with Triangular Non-Adiabatic Rapid Sweep (NARS) and Adiabatic Rapid Passage (ARP) EPR Spectroscopy

    PubMed Central

    Kittell, Aaron W.; Hyde, James S.

    2015-01-01

    Non-adiabatic rapid passage (NARS) electron paramagnetic resonance (EPR) spectroscopy was introduced by Kittell, A.W., Camenisch, T.G., Ratke, J.J. Sidabras, J.W., Hyde, J.S., 2011 as a general purpose technique to collect the pure absorption response. The technique has been used to improve sensitivity relative to sinusoidal magnetic field modulation, increase the range of inter-spin distances that can be measured under near physiological conditions, and enhance spectral resolution in copper (II) spectra. In the present work, the method is extended to CW microwave power saturation of spin-labeled T4 Lysozyme (T4L). As in the cited papers, rapid triangular sweep of the polarizing magnetic field was superimposed on slow sweep across the spectrum. Adiabatic rapid passage (ARP) effects were encountered in samples undergoing very slow rotational diffusion as the triangular magnetic field sweep rate was increased. The paper reports results of variation of experimental parameters at the interface of adiabatic and non-adiabatic rapid sweep conditions. Comparison of the forward (up) and reverse (down) triangular sweeps is shown to be a good indicator of the presence of rapid passage effects. Spectral turning points can be distinguished from spectral regions between turning points in two ways: differential microwave power saturation and differential passage effects. Oxygen accessibility data are shown under NARS conditions that appear similar to conventional field modulation data. However, the sensitivity is much higher, permitting, in principle, experiments at substantially lower protein concentrations. Spectral displays were obtained that appear sensitive to rotational diffusion in the range of rotational correlation times of 10−3 to 10−7 s in a manner that is analogous to saturation transfer spectroscopy. PMID:25917132

  9. Spin-label CW microwave power saturation and rapid passage with triangular non-adiabatic rapid sweep (NARS) and adiabatic rapid passage (ARP) EPR spectroscopy

    NASA Astrophysics Data System (ADS)

    Kittell, Aaron W.; Hyde, James S.

    2015-06-01

    Non-adiabatic rapid passage (NARS) electron paramagnetic resonance (EPR) spectroscopy was introduced by Kittell et al. (2011) as a general purpose technique to collect the pure absorption response. The technique has been used to improve sensitivity relative to sinusoidal magnetic field modulation, increase the range of inter-spin distances that can be measured under near physiological conditions (Kittell et al., 2012), and enhance spectral resolution in copper (II) spectra (Hyde et al., 2013). In the present work, the method is extended to CW microwave power saturation of spin-labeled T4 Lysozyme (T4L). As in the cited papers, rapid triangular sweep of the polarizing magnetic field was superimposed on slow sweep across the spectrum. Adiabatic rapid passage (ARP) effects were encountered in samples undergoing very slow rotational diffusion as the triangular magnetic field sweep rate was increased. The paper reports results of variation of experimental parameters at the interface of adiabatic and non-adiabatic rapid sweep conditions. Comparison of the forward (up) and reverse (down) triangular sweeps is shown to be a good indicator of the presence of rapid passage effects. Spectral turning points can be distinguished from spectral regions between turning points in two ways: differential microwave power saturation and differential passage effects. Oxygen accessibility data are shown under NARS conditions that appear similar to conventional field modulation data. However, the sensitivity is much higher, permitting, in principle, experiments at substantially lower protein concentrations. Spectral displays were obtained that appear sensitive to rotational diffusion in the range of rotational correlation times of 10-3 to 10-7 s in a manner that is analogous to saturation transfer spectroscopy.

  10. Spin-label CW microwave power saturation and rapid passage with triangular non-adiabatic rapid sweep (NARS) and adiabatic rapid passage (ARP) EPR spectroscopy.

    PubMed

    Kittell, Aaron W; Hyde, James S

    2015-06-01

    Non-adiabatic rapid passage (NARS) electron paramagnetic resonance (EPR) spectroscopy was introduced by Kittell et al. (2011) as a general purpose technique to collect the pure absorption response. The technique has been used to improve sensitivity relative to sinusoidal magnetic field modulation, increase the range of inter-spin distances that can be measured under near physiological conditions (Kittell et al., 2012), and enhance spectral resolution in copper (II) spectra (Hyde et al., 2013). In the present work, the method is extended to CW microwave power saturation of spin-labeled T4 Lysozyme (T4L). As in the cited papers, rapid triangular sweep of the polarizing magnetic field was superimposed on slow sweep across the spectrum. Adiabatic rapid passage (ARP) effects were encountered in samples undergoing very slow rotational diffusion as the triangular magnetic field sweep rate was increased. The paper reports results of variation of experimental parameters at the interface of adiabatic and non-adiabatic rapid sweep conditions. Comparison of the forward (up) and reverse (down) triangular sweeps is shown to be a good indicator of the presence of rapid passage effects. Spectral turning points can be distinguished from spectral regions between turning points in two ways: differential microwave power saturation and differential passage effects. Oxygen accessibility data are shown under NARS conditions that appear similar to conventional field modulation data. However, the sensitivity is much higher, permitting, in principle, experiments at substantially lower protein concentrations. Spectral displays were obtained that appear sensitive to rotational diffusion in the range of rotational correlation times of 10(-3) to 10(-7) s in a manner that is analogous to saturation transfer spectroscopy. PMID:25917132

  11. Determination of the Impact of Glycolate on ARP and MCU Operations

    SciTech Connect

    Taylor-Pashow, K. M.L.; Peters, T. B.; Fondeur, F. F.; Shehee, T. C.; Washington, A. L.

    2012-12-13

    Savannah River Remediation (SRR) is evaluating an alternate flowsheet for the Defense Waste Processing Facility (DWPF) using glycolic acid as a reductant. An important aspect of the development of the glycolic acid flowsheet is determining if glycolate has any detrimental downstream impacts. Testing was performed to determine if there is any impact to the strontium and actinide sorption by monosodium titanate (MST) and modified monosodium titanate (mMST) or if there is an impact to the cesium removal, phase separation, or coalescer performance at the Modular Caustic-Side Solvent Extraction Processing Unit (MCU). Sorption testing was performed using both MST and modified MST (mMST) in the presence of 5000 and 10,000 ppm (mass basis) glycolate. 10,000 ppm is the estimated bounding concentration expected in the DWPF recycle stream based on DWPF melter flammable gas model results. The presence of glycolate was found to slow the removal of Sr and Pu by MST, while increasing the removal rate of Np. Results indicate that the impact is a kinetic effect, and the overall capacity of the material is not affected. There was no measurable effect on U removal at either glycolate concentration. The slower removal rates for Sr and Pu at 5000 and 10,000 ppm glycolate could result in lower DF values for these sorbates in ARP based on the current (12 hours) and proposed (8 hours) contact times. For the highest glycolate concentration used in this study, the percentage of Sr removed at 6 hours of contact decreased by 1% and the percentage of Pu removed decreased by nearly 7%. The impact may prove insignificant if the concentration of glycolate that is returned to the tank farm is well below the concentrations tested in this study. The presence of glycolate also decreased the removal rates for all three sorbates (Sr, Pu, and Np) by mMST. Similar to MST, the results for mMST indicate that the impact is a kinetic effect, and the overall capacity of the material is not affected. The

  12. Constraining Gamma-Ray Emission from Luminous Infrared Galaxies with Fermi-LAT; Tentative Detection of Arp 220

    NASA Astrophysics Data System (ADS)

    Griffin, Rhiannon D.; Dai, Xinyu; Thompson, Todd A.

    2016-05-01

    Star-forming galaxies produce gamma-rays primarily via pion production, resulting from inelastic collisions between cosmic-ray protons and the interstellar medium (ISM). The dense ISM and high star formation rates of luminous and ultra-luminous infrared galaxies (LIRGs and ULIRGs) imply that they should be strong gamma-ray emitters, but so far only two LIRGs have been detected. Theoretical models for their emission depend on the unknown fraction of cosmic-ray protons that escape these galaxies before interacting. We analyze Fermi-LAT data for 82 of the brightest Infrared Astronomical Satellite LIRGs and ULIRGs. We examine each system individually and carry out a stacking analysis to constrain their gamma-ray fluxes. We report the detection of the nearest ULIRG Arp 220 (˜4.6σ). We observe a gamma-ray flux (0.8–100 GeV) of 2.4 × 10‑10 phot cm‑2 s‑1 with a photon index of 2.23 (8.2 × 1041 erg s‑1 at 77 Mpc). We also derive upper limits (ULs) for the stacked LIRGs and ULIRGs. The gamma-ray luminosity of Arp 220 and the stacked ULs agree with calorimetric predictions for dense star-forming galaxies. With the detection of Arp 220, we extend the gamma-ray–IR luminosity correlation to the high-luminosity regime with {log}{L}0.1-100{GeV}=1.25× {log}{L}8-1000μ {{m}}+26.7 as well as the gamma-ray–radio continuum luminosity correlation with {log}{L}0.1-100{GeV}=1.22× {log}{L}1.4{GHz}+13.3. The current survey of Fermi-LAT is on the verge of detecting more LIRGs/ULIRGs in the local universe, and we expect even more detections with deeper Fermi-LAT observations or the next generation of gamma-ray detectors.

  13. Constraining Gamma-Ray Emission from Luminous Infrared Galaxies with Fermi-LAT; Tentative Detection of Arp 220

    NASA Astrophysics Data System (ADS)

    Griffin, Rhiannon D.; Dai, Xinyu; Thompson, Todd A.

    2016-05-01

    Star-forming galaxies produce gamma-rays primarily via pion production, resulting from inelastic collisions between cosmic-ray protons and the interstellar medium (ISM). The dense ISM and high star formation rates of luminous and ultra-luminous infrared galaxies (LIRGs and ULIRGs) imply that they should be strong gamma-ray emitters, but so far only two LIRGs have been detected. Theoretical models for their emission depend on the unknown fraction of cosmic-ray protons that escape these galaxies before interacting. We analyze Fermi-LAT data for 82 of the brightest Infrared Astronomical Satellite LIRGs and ULIRGs. We examine each system individually and carry out a stacking analysis to constrain their gamma-ray fluxes. We report the detection of the nearest ULIRG Arp 220 (∼4.6σ). We observe a gamma-ray flux (0.8–100 GeV) of 2.4 × 10‑10 phot cm‑2 s‑1 with a photon index of 2.23 (8.2 × 1041 erg s‑1 at 77 Mpc). We also derive upper limits (ULs) for the stacked LIRGs and ULIRGs. The gamma-ray luminosity of Arp 220 and the stacked ULs agree with calorimetric predictions for dense star-forming galaxies. With the detection of Arp 220, we extend the gamma-ray–IR luminosity correlation to the high-luminosity regime with {log}{L}0.1-100{GeV}=1.25× {log}{L}8-1000μ {{m}}+26.7 as well as the gamma-ray–radio continuum luminosity correlation with {log}{L}0.1-100{GeV}=1.22× {log}{L}1.4{GHz}+13.3. The current survey of Fermi-LAT is on the verge of detecting more LIRGs/ULIRGs in the local universe, and we expect even more detections with deeper Fermi-LAT observations or the next generation of gamma-ray detectors.

  14. The FAK–Arp2/3 interaction promotes leading edge advance and haptosensing by coupling nascent adhesions to lamellipodia actin

    PubMed Central

    Swaminathan, Vinay; Fischer, R. S.; Waterman, Clare M.

    2016-01-01

    Cell migration is initiated in response to biochemical or physical cues in the environment that promote actin-mediated lamellipodial protrusion followed by the formation of nascent integrin adhesions (NAs) within the protrusion to drive leading edge advance. Although FAK is known to be required for cell migration through effects on focal adhesions, its role in NA formation and lamellipodial dynamics is unclear. Live-cell microscopy of FAK−/− cells with expression of phosphorylation deficient or a FERM-domain mutant deficient in Arp2/3 binding revealed a requirement for FAK in promoting the dense formation, transient stabilization, and timely turnover of NA within lamellipodia to couple actin-driven protrusion to adhesion and advance of the leading edge. Phosphorylation on Y397 of FAK promotes dense NA formation but is dispensable for transient NA stabilization and leading edge advance. In contrast, transient NA stabilization and advance of the cell edge requires FAK–Arp2/3 interaction, which promotes Arp2/3 localization to NA and reduces FAK activity. Haptosensing of extracellular matrix (ECM) concentration during migration requires the interaction between FAK and Arp2/3, whereas FAK phosphorylation modulates mechanosensing of ECM stiffness during spreading. Taken together, our results show that mechanistically separable functions of FAK in NA are required for cells to distinguish distinct properties of their environment during migration. PMID:26842895

  15. First Detection of GeV Emission from an Ultraluminous Infrared Galaxy: Arp 220 as Seen with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Peng, Fang-Kun; Wang, Xiang-Yu; Liu, Ruo-Yu; Tang, Qing-Wen; Wang, Jun-Feng

    2016-04-01

    Cosmic rays (CRs) in starburst galaxies produce high-energy gamma-rays by colliding with the dense interstellar medium. Arp 220 is the nearest ultraluminous infrared galaxy that has star formation at extreme levels, so it has long been predicted to emit high-energy gamma-rays. However, no evidence of gamma-ray emission was found despite intense search efforts. Here we report the discovery of high-energy gamma-ray emission above 200 MeV from Arp 220 at a confidence level of ∼6.3σ using 7.5 years of Fermi Large Area Telescope observations. The gamma-ray emission shows no significant variability over the observation period and it is consistent with the quasi-linear scaling relation between the gamma-ray luminosity and total infrared luminosity for star-forming galaxies, suggesting that these gamma-rays arise from CR interactions. As the high-density medium of Arp 220 makes it an ideal CR calorimeter, the gamma-ray luminosity can be used to measure the efficiency of powering CRs by supernova (SN) remnants given a known supernova rate in Arp 220. We find that this efficiency is about 4.2 ± 2.6% for CRs above 1 GeV.

  16. Arp2/3 Controls the Motile Behavior of N-WASP-Functionalized GUVs and Modulates N-WASP Surface Distribution by Mediating Transient Links with Actin Filaments

    PubMed Central

    Delatour, Vincent; Helfer, Emmanuèle; Didry, Dominique; Lê, Kim Hô Diêp; Gaucher, Jean-François; Carlier, Marie-France; Romet-Lemonne, Guillaume

    2008-01-01

    Spatially controlled assembly of actin in branched filaments generates cell protrusions or the propulsion of intracellular vesicles and pathogens. The propulsive movement of giant unilamellar vesicles (GUVs) functionalized by N-WASP (full-length or truncated) is reconstituted in a biochemically controlled medium, and analyzed using phase contrast and fluorescence microscopy to elucidate the links between membrane components and the actin cytoskeleton that determine motile behavior. Actin-based propulsion displays a continuous regime or a periodic saltatory regime. The transition between the two regimes is controlled by the concentration of Arp2/3 complex, which branches filaments by interacting with N-WASP at the liposome surface. Saltatory motion is linked to cycles in the distribution of N-WASP at the membrane between a homogeneous and a segregated state. Comparison of the changes in distribution of N-WASP, Arp2/3, and actin during propulsion demonstrates that actin filaments bind to N-WASP, and that these bonds are transitory. This interaction, mediated by Arp2/3, drives N-WASP segregation. VC-fragments of N-WASP, that interact more weakly than N-WASP with the Arp2/3 complex, segregate less than N-WASP at the rear of the GUVs. GUV propulsion is inhibited by the presence of VCA-actin covalent complex, showing that the release of actin from the nucleator is required for movement. The balance between segregation and free diffusion determines whether continuous movement can be sustained. Computed surface distributions of N-WASP, derived from a theoretical description of this segregation-diffusion mechanism, account satisfactorily for the measured density profiles of N-WASP, Arp2/3 complex, and actin. PMID:18326652

  17. The Neutral Hydrogen Disk of ARP 10 (=VV 362): A Nonequilibrium Disk Associated with a Galaxy with Rings and Ripples

    NASA Astrophysics Data System (ADS)

    Charmandaris, V.; Appleton, P. N.

    1996-04-01

    We present VLA H I and optical spectra of the peculiar galaxy Arp 10. Originally believed to be an example of a classical colliding ring galaxy with multiple rings, the new observations show a large disturbed neutral hydrogen disk extending 2.7 times the radius of the bright optical ring. We also present evidence for optical shells or ripples in the outer isophotes of the galaxy reminiscent of the ripples seen in some early type systems. The small elliptical originally believed to be the companion is shown to be a background galaxy. The H I disk consists of two main parts: a very irregular outer structure, and a more regular inner disk associated with the main bright optical ring. In both cases, the H I structures do not exactly trace the optical morphology. In the outer parts, the H I distribution does not correlate well with the optical ripples. Even the inner H I disk does not correspond well morphologically nor kinematically to the optical rings. These peculiarities lead us to believe that the potential in which the H I disk resides is significantly out of equilibrium --- a situation which would inherently produce rings of star formation. We suggest that Arp 10 is the result of the intermediate stage of a merger between a large H I rich disk and a gas-poor disk system. As such, it may represent an example of a class of mergers which lies intermediate between the ``ripple and shell'' accretion systems and the head-on collisional ring galaxies.

  18. THE LICK AGN MONITORING PROJECT: VELOCITY-DELAY MAPS FROM THE MAXIMUM-ENTROPY METHOD FOR Arp 151

    SciTech Connect

    Bentz, Misty C.; Barth, Aaron J.; Walsh, Jonelle L.; Horne, Keith; Bennert, Vardha Nicola; Treu, Tommaso; Canalizo, Gabriela; Filippenko, Alexei V.; Gates, Elinor L.; Malkan, Matthew A.; Minezaki, Takeo; Woo, Jong-Hak

    2010-09-01

    We present velocity-delay maps for optical H I, He I, and He II recombination lines in Arp 151, recovered by fitting a reverberation model to spectrophotometric monitoring data using the maximum-entropy method. H I response is detected over the range 0-15 days, with the response confined within the virial envelope. The Balmer-line maps have similar morphologies but exhibit radial stratification, with progressively longer delays for H{gamma} to H{beta} to H{alpha}. The He I and He II response is confined within 1-2 days. There is a deficit of prompt response in the Balmer-line cores but strong prompt response in the red wings. Comparison with simple models identifies two classes that reproduce these features: free-falling gas and a half-illuminated disk with a hot spot at small radius on the receding lune. Symmetrically illuminated models with gas orbiting in an inclined disk or an isotropic distribution of randomly inclined circular orbits can reproduce the virial structure but not the observed asymmetry. Radial outflows are also largely ruled out by the observed asymmetry. A warped-disk geometry provides a physically plausible mechanism for the asymmetric illumination and hot spot features. Simple estimates show that a disk in the broad-line region of Arp 151 could be unstable to warping induced by radiation pressure. Our results demonstrate the potential power of detailed modeling combined with monitoring campaigns at higher cadence to characterize the gas kinematics and physical processes that give rise to the broad emission lines in active galactic nuclei.

  19. DETERMINATION OF THE IMPACT OF GLYCOLATE ON ARP AND MCU OPERATIONS

    SciTech Connect

    Taylor-Pashow, K.; Peters, T.; Shehee, T.

    2012-06-04

    Savannah River Remediation (SRR) is evaluating an alternate flowsheet for the Defense Waste Processing Facility (DWPF) using glycolic acid as a reductant. An important aspect of the development of the glycolic acid flowsheet is determining if glycolate has any detrimental downstream impacts. Testing was performed to determine if there is any impact to the strontium and actinide sorption by monosodium titanate (MST) and modified monosodium titanate (mMST) or if there is an impact to the cesium removal at the Modular Caustic-Side Solvent Extraction Processing Unit (MCU). Sorption testing was performed using both MST and modified MST (mMST) in the presence of 5,000 and 10,000 ppm (mass basis) glycolate. 10,000 ppm is the estimated bounding concentration expected in the DWPF recycle stream based on DWPF melter flammable gas model results. The presence of glycolate was found to slow the removal of Sr and Pu by MST, while increasing the removal rate of Np. Results indicate that the impact is a kinetic effect, and the overall capacity of the material is not affected. There was no measurable effect on U removal at either glycolate concentration. The slower removal rates for Sr and Pu at 5,000 and 10,000 ppm glycolate could result in lower DF values for these sorbates in ARP based on the current (12 hours) and proposed (8 hours) contact times. For the highest glycolate concentration used in this study, the percentage of Sr removed at 6 hours of contact decreased by 1% and the percentage of Pu removed decreased by nearly 7%. The impact may prove insignificant if the concentration of glycolate that is returned to the tank farm is well below the concentrations tested in this study. The presence of glycolate also decreased the removal rates for all three sorbates (Sr, Pu, and Np) by mMST. Similarly to MST, the results for mMST indicate that the impact is a kinetic effect, and the overall capacity of the material is not affected. The presence of glycolate did not change the lack

  20. DEMONSTRATION OF THE DWPF FLOWSHEET IN THE SRNL SHIELDED CELLS USING ARP PRODUCT SIMULANT AND SB4 TANK 40 SLUDGE SLURRY

    SciTech Connect

    Lambert, D; John Pareizs, J; Bradley Pickenheim, B; Cj Bannochie, C; Michael Stone, M; Damon Click, D; Erich Hansen, E; Kim Crapse, K; David Hobbs, D

    2008-05-14

    The radioactive startup of two new SRS processing facilities, the Actinide Removal Process (ARP) and the Modular Caustic-Side-Solvent-Extraction Unit (MCU) will add two new waste streams to the Defense Waste Processing Facility (DWPF). The ARP will remove actinides from the 5.6 M salt solution resulting in a sludge-like product that is roughly half monosodium titanate (MST) insoluble solids and half sludge insoluble solids. The ARP product will be added to the Sludge Receipt and Adjustment Tank (SRAT) at boiling and dewatered prior to pulling a SRAT receipt sample. The cesium rich MCU stream will be added to the SRAT at boiling after both formic and nitric acid have been added and the SRAT contents concentrated to the appropriate endpoint. A concern was raised by an external hydrogen review panel that the actinide loaded MST could act as a catalyst for hydrogen generation (Mar 15, 2007 report, Recommendation 9). Hydrogen generation, and it's potential to form a flammable mixture in the off-gas, under SRAT and Slurry Mix Evaporator (SME) processing conditions has been a concern since the discovery that noble metals catalyze the decomposition of formic acid. Radiolysis of water also generates hydrogen, but the radiolysis rate is orders of magnitude lower than the noble metal catalyzed generation. As a result of the concern raised by the external hydrogen review panel, hydrogen generation was a prime consideration in this experiment. Testing was designed to determine whether the presence of the irradiated ARP simulant containing MST caused uncontrolled or unexpected hydrogen production during experiments simulating the DWPF Chemical Process Cell (CPC) due to activation of titanium. A Shielded Cells experiment, SC-5, was completed using SB4 sludge from Tank 405 combined with an ARP product produced from simulants by SRNL researchers. The blend of sludge and MST was designed to be prototypic of planned DWPF SRAT and SME cycles. As glass quality was not an objective in

  1. IMPACT OF SB4 TANK 40 DECANT AND ARP/MCU ADDITIONS WITH/WITHOUT ADDED CAUSTIC ON DWPF CPC PERFORMANCE

    SciTech Connect

    Koopman, D; David Best, D; Frances Williams, F

    2008-04-18

    The Savannah River National Laboratory (SRNL) was requested to investigate the impact of decanting supernate from the Sludge Batch four (SB4) feed in Tank 40. The specific questions concerned the potential impact on the stoichiometric acid window determined for SB4 with respect to overall hydrogen generation rates, nitrite destruction in the Sludge Receipt and Adjustment Tank (SRAT) and the rheology of the sludge, SRAT product, and Slurry Mix Evaporator (SME) product slurries. The scope included considering an addition of sodium hydroxide to Tank 40 to partially offset the sodium lost during decanting as well as considering the impact of bounding quantities of Actinide Removal Process (ARP) feed and Modular Caustic-Side Solvent Extraction Unit (MCU) feed on these same parameters. Simulated SB4 waste was first adjusted to match the dilution that has occurred in Tank 40 during the initial period of SB4 operations in the DWPF. The adjusted simulant was decanted an equivalent of 100,000 gallons relative to 413,740 gallons projected supernate volume. The decanted simulant was divided into two equal parts. One part received an addition of sodium hydroxide to increase the Na{sub 2}O content of the calcined sludge solids by about 3%. The baseline decanted simulant and caustic adjusted simulant were each tested in three pairs of DWPF process simulations of the SRAT and SME cycles. The simulations were at the nominal SB4 acid stoichiometry of 130% with and without bounding ARP/MCU additions and at 170% of acid without ARP/MCU. The 170% case without ARP/MCU was considered bounding relative to 170% with ARP/MCU based on calculated acid requirements. No significant negative impacts on the proposed acid operating window for the SRAT and SME cycles were noted in the simulations. Nitrite was successfully destroyed and mercury reduced in all six SRAT cycles. Hydrogen was produced in all six SRAT and SME cycles, but the levels were below the DWPF SRAT and SME cycle limits in all

  2. Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H2O, H218O, OH, 18OH, O I, HCN, and NH3

    NASA Astrophysics Data System (ADS)

    González-Alfonso, E.; Fischer, J.; Graciá-Carpio, J.; Sturm, E.; Hailey-Dunsheath, S.; Lutz, D.; Poglitsch, A.; Contursi, A.; Feuchtgruber, H.; Veilleux, S.; Spoon, H. W. W.; Verma, A.; Christopher, N.; Davies, R.; Sternberg, A.; Genzel, R.; Tacconi, L.

    2012-05-01

    Full range Herschel/PACS spectroscopy of the (ultra)luminous infrared galaxies NGC 4418 and Arp 220, observed as part of the SHINING key programme, reveals high excitation in H2O, OH, HCN, and NH3. In NGC 4418, absorption lines were detected with Elower > 800 K (H2O), 600 K (OH), 1075 K (HCN), and 600 K (NH3), while in Arp 220 the excitation is somewhat lower. While outflow signatures in moderate excitation lines are seen in Arp 220 as have been seen in previous studies, in NGC 4418 the lines tracing its outer regions are redshifted relative to the nucleus, suggesting an inflow with Ṁ ≲ 12 M⊙ yr-1. Both galaxies have compact and warm (Tdust ≳ 100 K) nuclear continuum components, together with a more extended and colder component that is much more prominent and massive in Arp 220. A chemical dichotomy is found in both sources: on the one hand, the nuclear regions have high H2O abundances, ~10-5, and high HCN/H2O and HCN/NH3 column density ratios of 0.1-0.4 and 2-5, respectively, indicating a chemistry typical of evolved hot cores where grain mantle evaporation has occurred. On the other hand, the high OH abundance, with OH/H2O ratios of ~0.5, indicates the effects of X-rays and/or cosmic rays. The nuclear media have high surface brightnesses (≳1013 L⊙/kpc2) and are estimated to be very thick (NH ≳ 1025 cm-2). While NGC 4418 shows weak absorption in H218O and 18OH, with a 16O-to-18O ratio of ≳250-500, the relatively strong absorption of the rare isotopologues in Arp 220 indicates 18O enhancement, with 16O-to-18O of 70-130. Further away from the nuclear regions, the H2O abundance decreases to ≲10-7 and the OH/H2O ratio is reversed relative to the nuclear region to 2.5-10. Despite the different scales and morphologies of NGC 4418, Arp 220, and Mrk 231, preliminary evidence is found for an evolutionary sequence from infall, hot-core like chemistry, and solar oxygen isotope ratio to high velocity outflow, disruption of the hot core chemistry and

  3. A Single Target Is Sufficient To Account for the Biological Effects of the A-Factor Receptor Protein of Streptomyces griseus

    PubMed Central

    Kato, Jun-ya; Miyahisa, Ikuo; Mashiko, Mari; Ohnishi, Yasuo; Horinouchi, Sueharu

    2004-01-01

    In the model of the A-factor (2-isocapryloyl-3R-hydroxymethyl-γ-butyrolactone) regulatory cascade in Streptomyces griseus, A-factor binds ArpA, the A-factor receptor protein, that has bound to the adpA promoter and dissociates it from the DNA, thus inducing the transcription of adpA. AdpA switches on the transcription of a number of genes required for secondary metabolism and morphological differentiation, forming an AdpA regulon. Consistent with this model, arpA null mutants produced streptomycin and a yellow pigment in larger amounts and formed aerial hyphae from an earlier growth stage than the wild-type strain. On the other hand, mutant MK2, expressing a mutant ArpA (Trp119Ala), neither produced secondary metabolites nor formed aerial hyphae, because this A-factor-insensitive mutant ArpA always bound to and repressed the adpA promoter due to the amino acid replacement of Trp-119 with Ala. Introduction of adpA under the control of a foreign promoter into mutant MK2 restored all of the phenotypes that we could observe, which suggests that the only significant target of ArpA is adpA. In contrast to other γ-butyrolactone regulatory systems, disruption of arpA had no effect on A-factor production, indicating that ArpA does not regulate A-factor biosynthesis. Instead, A-factor production was found to be repressed by AdpA in a two-step regulatory feedback loop. PMID:15028707

  4. COMMIX-1AR/P: A three-dimensional transient single-phase computer program for thermal hydraulic analysis of single and multicomponent systems

    SciTech Connect

    Garner, P.L.; Blomquist, R.N.; Gelbard, E.M.

    1992-09-01

    The COMMIX-1AR/P computer program is designed for analyzing the steady-state and transient aspects of single-phase fluid flow and heat transfer in three spatial dimensions. This version is an extension of the modeling in COMMIX-1A to include multiple fluids in physically separate regions of the computational domain, modeling descriptions for pumps, radiation heat transfer between surfaces of the solids which are embedded in or surround the fluid, a k-[var epsilon] model for fluid turbulence, and improved numerical techniques. The porous-medium formulation in COMMIX allows the program to be applied to a wide range of problems involving both simple and complex geometrical arrangements. The input preparation and execution procedures are presented for the COMMIX-1AR/P program and several postprocessor programs which produce graphical displays of the calculated results.

  5. Comparison of CDC and sequence-based molecular typing of syphilis treponemes: tpr and arp loci are variable in multiple samples from the same patient

    PubMed Central

    2013-01-01

    Background Molecular typing of syphilis-causing strains provides important epidemiologic data. We tested whether identified molecular subtypes were identical in PCR-positive parallel samples taken from the same patient at a same time. We also tested whether subtype prevalence differs in skin and blood samples. Results Eighteen syphilis positive patients (showing both positive serology and PCR), with two PCR-typeable parallel samples taken at the same time, were tested with both CDC (Centers for Disease Control and Prevention) and sequence-based typing. Samples taken from 9 of 18 patients were completely typed for TP0136, TP0548, 23S rDNA, arp, and tpr loci. The CDC typing revealed 11 distinct genotypes while the sequence-based typing identified 6 genotypes. When results from molecular typing of TP0136, TP0548, and 23S rDNA were analyzed in samples taken from the same patient, no discrepancies in the identified genotypes were found; however, there were discrepancies in 11 of 18 patients (61.1%) samples relative to the arp and tpr loci. In addition to the above described typing, 127 PCR-positive swabs and whole blood samples were tested for individual genotype frequencies. The repetition number for the arp gene was lower in whole blood (WB) samples compared to swab samples. Similarly, the most common tpr RFLP type “d” was found to have lower occurrence rates in WB samples while type “e” had an increased occurrence in these samples. Conclusions Differences in the CDC subtypes identified in parallel samples indicated genetic instability of the arp and tpr loci and suggested limited applicability of the CDC typing system in epidemiological studies. Differences in treponemal genotypes detected in whole blood and swab samples suggested important differences between both compartments and/or differences in adherence of treponeme variants to human cells. PMID:23898829

  6. Squamosamide derivative FLZ inhibits TNF-α-induced ICAM-1 expression via down-regulation of the NF-κB signaling pathway in ARPE-19 cells

    PubMed Central

    Feng, Ting-Ting; Liang, Ze-Yu; Chen, Song

    2015-01-01

    Dysfunction of the retinal pigment epithelium (RPE) resulting from chronic inflammation is implicated in the pathogenesis of age-related macular degeneration (AMD). It has been reported that tumor necrosis factor-α (TNF-α) could induce intercellular adhesion molecule-1 (ICAM-1) expression in RPE cells. FLZ, a novel synthetic squamosamide derivative from a Chinese herb, Annona glabra, has displayed significant anti-inflammatory activity. However, the effects of FLZ on TNF-α-induced ICAM-1 expression in RPE cells remain unknown. Therefore, in the present study, we evaluated the effects of FLZ on TNF-α-induced ICAM-1 expression in RPE cells. We found that FLZ prevented TNF-α-induced ICAM-1 expression and the ability of monocytes to adhere to ARPE-19 cells induced by TNF-α. Furthermore, FLZ inhibited TNF-α-induced NF-κB p65 expression, as well as phosphorylation of IκBα in ARPE-19 cells. Taken together, these results suggest that FLZ inhibited TNF-α-induced ICAM-1 expression through blocking NF-κB signaling pathway in ARPE-19 cells. Thus, FLZ could be used for designing novel therapeutic agents against AMD. PMID:26464656

  7. Squamosamide derivative FLZ inhibits TNF-α-induced ICAM-1 expression via down-regulation of the NF-κB signaling pathway in ARPE-19 cells.

    PubMed

    Feng, Ting-Ting; Liang, Ze-Yu; Chen, Song

    2015-01-01

    Dysfunction of the retinal pigment epithelium (RPE) resulting from chronic inflammation is implicated in the pathogenesis of age-related macular degeneration (AMD). It has been reported that tumor necrosis factor-α (TNF-α) could induce intercellular adhesion molecule-1 (ICAM-1) expression in RPE cells. FLZ, a novel synthetic squamosamide derivative from a Chinese herb, Annona glabra, has displayed significant anti-inflammatory activity. However, the effects of FLZ on TNF-α-induced ICAM-1 expression in RPE cells remain unknown. Therefore, in the present study, we evaluated the effects of FLZ on TNF-α-induced ICAM-1 expression in RPE cells. We found that FLZ prevented TNF-α-induced ICAM-1 expression and the ability of monocytes to adhere to ARPE-19 cells induced by TNF-α. Furthermore, FLZ inhibited TNF-α-induced NF-κB p65 expression, as well as phosphorylation of IκBα in ARPE-19 cells. Taken together, these results suggest that FLZ inhibited TNF-α-induced ICAM-1 expression through blocking NF-κB signaling pathway in ARPE-19 cells. Thus, FLZ could be used for designing novel therapeutic agents against AMD. PMID:26464656

  8. The Entamoeba histolytica, Arp2/3 Complex Is Recruited to Phagocytic Cups through an Atypical Kinase EhAK1

    PubMed Central

    Babuta, Mrigya; Mansuri, M Shahid; Bhattacharya, Sudha; Bhattacharya, Alok

    2015-01-01

    The parasite Entamoeba histolytica is the etiological agent of amoebiasis and phagocytosis plays a key role in virulence of this organism. Signaling pathways involved in activation of cytoskeletal dynamics required for phagocytosis remain to be elucidated. Phagocytosis is initiated with sequential recruitment of EhC2PK, EhCaBP1, EhCaBP3 and an atypical kinase EhAK1 after particle attachment. Here we show that EhARPC1, an essential subunit of the actin branching complex Arp 2/3 is recruited to the phagocytic initiation sites by EhAK1. Imaging, expression knockdown of different molecules and pull down experiments suggest that EhARPC1 interacts with EhAK1 and that it is required during initiation of phagocytosis and phagosome formation. Moreover, recruitment of EhARPC2 at the phagocytosis initiation by EhAK1 is also observed, indicating that the Arp 2/3 complex is recruited. In conclusion, these results suggests a novel mechanism of recruitment of Arp 2/3 complex during phagocytosis in E. histolytica. PMID:26646565

  9. An Arp2/3 nucleated F-actin shell fragments nuclear membranes at nuclear envelope breakdown in starfish oocytes.

    PubMed

    Mori, Masashi; Somogyi, Kálmán; Kondo, Hiroshi; Monnier, Nilah; Falk, Henning J; Machado, Pedro; Bathe, Mark; Nédélec, François; Lénárt, Péter

    2014-06-16

    Animal cells disassemble and reassemble their nuclear envelopes (NEs) upon each division. Nuclear envelope breakdown (NEBD) serves as a major regulatory mechanism by which mixing of cytoplasmic and nuclear compartments drives the complete reorganization of cellular architecture, committing the cell for division. Breakdown is initiated by phosphorylation-driven partial disassembly of the nuclear pore complexes (NPCs), increasing their permeability but leaving the overall NE structure intact. Subsequently, the NE is rapidly broken into membrane fragments, defining the transition from prophase to prometaphase and resulting in complete mixing of cyto- and nucleoplasm. However, the mechanism underlying this rapid NE fragmentation remains largely unknown. Here, we show that NE fragmentation during NEBD in starfish oocytes is driven by an Arp2/3 complex-nucleated F-actin "shell" that transiently polymerizes on the inner surface of the NE. Blocking the formation of this F-actin shell prevents membrane fragmentation and delays entry of large cytoplasmic molecules into the nucleus. We observe spike-like protrusions extending from the F-actin shell that appear to "pierce" the NE during the fragmentation process. Finally, we show that NE fragmentation is essential for successful reproduction, because blocking this process in meiosis leads to formation of aneuploid eggs. PMID:24909322

  10. High harmonic generation based time resolved ARPES at 30 eV with 50 meV energy resolution

    NASA Astrophysics Data System (ADS)

    Rohwer, Timm; Sie, Edbert J.; Mahmood, Fahad; Gedik, Nuh

    Angle-resolved photoelectron spectroscopy (ARPES) has emerged as a leading technique in identifying equilibrium properties of complex electronic systems as well as their correlated dynamics. By using femtosecond high harmonic generation (HHG) pulses, this technique can be extended to monitor ultrafast changes in the electronic structure in response to an optical excitation. However, the broad bandwidth of the HHG pulses has been a major experimental limitation. In this contribution, we combine the HHG source with an off-axis Czerny-Turner XUV monochromator and a three-dimensional ``ARTOF'' photoelectron detector to achieve an unrivaled overall energy resolution of 50 meV in multiple harmonic energies. Moreover, the use of a stack of different gratings enables us to fine control both the photon energy and time vs. energy resolution to its particular needs. The performance of our setup is demonstrated by studies on the transition metal dichalcogenide IrTe2 which undergoes a first-order structural transition and accompanied reconstruction of the band structure upon cooling without the characteristic opening of an energy gap.

  11. PICK1 is implicated in organelle motility in an Arp2/3 complex-independent manner.

    PubMed

    Madasu, Yadaiah; Yang, Changsong; Boczkowska, Malgorzata; Bethoney, Kelley A; Zwolak, Adam; Rebowski, Grzegorz; Svitkina, Tatyana; Dominguez, Roberto

    2015-04-01

    PICK1 is a modular scaffold implicated in synaptic receptor trafficking. It features a PDZ domain, a BAR domain, and an acidic C-terminal tail (ACT). Analysis by small- angle x-ray scattering suggests a structural model that places the receptor-binding site of the PDZ domain and membrane-binding surfaces of the BAR and PDZ domains adjacent to each other on the concave side of the banana-shaped PICK1 dimer. In the model, the ACT of one subunit of the dimer interacts with the PDZ and BAR domains of the other subunit, possibly accounting for autoinhibition. Consistently, full-length PICK1 shows diffuse cytoplasmic localization, but it clusters on vesicle-like structures that colocalize with the trans-Golgi network marker TGN38 upon deletion of either the ACT or PDZ domain. This localization is driven by the BAR domain. Live-cell imaging further reveals that PICK1-associated vesicles undergo fast, nondirectional motility in an F-actin-dependent manner, but deleting the ACT dramatically reduces vesicle speed. Thus the ACT links PICK1-associated vesicles to a motility factor, likely myosin, but, contrary to previous reports, PICK1 neither binds nor inhibits Arp2/3 complex. PMID:25657323

  12. Quantifying electronic correlation strength in a complex oxide: A combined DMFT and ARPES study of LaNiO3

    NASA Astrophysics Data System (ADS)

    Nowadnick, E. A.; Ruf, J. P.; Park, H.; King, P. D. C.; Schlom, D. G.; Shen, K. M.; Millis, A. J.

    2015-12-01

    The electronic correlation strength is a basic quantity that characterizes the physical properties of materials such as transition metal oxides. Determining correlation strengths requires both precise definitions and a careful comparison between experiment and theory. In this paper, we define the correlation strength via the magnitude of the electron self-energy near the Fermi level. For the case of LaNiO3, we obtain both the experimental and theoretical mass enhancements m⊙/m by considering high resolution angle-resolved photoemission spectroscopy (ARPES) measurements and density functional + dynamical mean field theory (DFT + DMFT) calculations. We use valence-band photoemission data to constrain the free parameters in the theory and demonstrate a quantitative agreement between the experiment and theory when both the realistic crystal structure and strong electronic correlations are taken into account. In addition, by considering DFT + DMFT calculations on epitaxially strained LaNiO3, we find a strain-induced evolution of m⊙/m in qualitative agreement with trends derived from optics experiments. These results provide a benchmark for the accuracy of the DFT + DMFT theoretical approach, and can serve as a test case when considering other complex materials. By establishing the level of accuracy of the theory, this work also will enable better quantitative predictions when engineering new emergent properties in nickelate heterostructures.

  13. ARPES view on surface and bulk hybridization phenomena in the antiferromagnetic Kondo lattice CeRh2Si2

    PubMed Central

    Patil, S.; Generalov, A.; Güttler, M.; Kushwaha, P.; Chikina, A.; Kummer, K.; Rödel, T. C.; Santander-Syro, A. F.; Caroca-Canales, N.; Geibel, C.; Danzenbächer, S.; Kucherenko, Yu.; Laubschat, C.; Allen, J. W.; Vyalikh, D. V.

    2016-01-01

    The hybridization between localized 4f electrons and itinerant electrons in rare-earth-based materials gives rise to their exotic properties like valence fluctuations, Kondo behaviour, heavy-fermions, or unconventional superconductivity. Here we present an angle-resolved photoemission spectroscopy (ARPES) study of the Kondo lattice antiferromagnet CeRh2Si2, where the surface and bulk Ce-4f spectral responses were clearly resolved. The pronounced 4f 0 peak seen for the Ce terminated surface gets strongly suppressed in the bulk Ce-4f spectra taken from a Si-terminated crystal due to much larger f-d hybridization. Most interestingly, the bulk Ce-4f spectra reveal a fine structure near the Fermi edge reflecting the crystal electric field splitting of the bulk magnetic 4f 15/2 state. This structure presents a clear dispersion upon crossing valence states, providing direct evidence of f-d hybridization. Our findings give precise insight into f-d hybridization penomena and highlight their importance in the antiferromagnetic phases of Kondo lattices. PMID:26987899

  14. ARPES view on surface and bulk hybridization phenomena in the antiferromagnetic Kondo lattice CeRh2Si2.

    PubMed

    Patil, S; Generalov, A; Güttler, M; Kushwaha, P; Chikina, A; Kummer, K; Rödel, T C; Santander-Syro, A F; Caroca-Canales, N; Geibel, C; Danzenbächer, S; Kucherenko, Yu; Laubschat, C; Allen, J W; Vyalikh, D V

    2016-01-01

    The hybridization between localized 4f electrons and itinerant electrons in rare-earth-based materials gives rise to their exotic properties like valence fluctuations, Kondo behaviour, heavy-fermions, or unconventional superconductivity. Here we present an angle-resolved photoemission spectroscopy (ARPES) study of the Kondo lattice antiferromagnet CeRh2Si2, where the surface and bulk Ce-4f spectral responses were clearly resolved. The pronounced 4f (0) peak seen for the Ce terminated surface gets strongly suppressed in the bulk Ce-4f spectra taken from a Si-terminated crystal due to much larger f-d hybridization. Most interestingly, the bulk Ce-4f spectra reveal a fine structure near the Fermi edge reflecting the crystal electric field splitting of the bulk magnetic 4f (1)5/2 state. This structure presents a clear dispersion upon crossing valence states, providing direct evidence of f-d hybridization. Our findings give precise insight into f-d hybridization penomena and highlight their importance in the antiferromagnetic phases of Kondo lattices. PMID:26987899

  15. Secretory proteins characteristic of environmental changes in cellular signal transduction: Expression in oral fluid

    NASA Astrophysics Data System (ADS)

    Mednieks, M. I.; Burke, J. C.; Sivakumar, T. P.; Hand, A. R.; Grindeland, R. E.

    2000-01-01

    Past studies have shown that both hypo- and hyper-gravity have significant consequences on a variety of tissues and organ systems. It is not known if the effects of environmental stimuli such as altered gravity are beneficial or detrimental, and if the effects can be prevented or reversed. Animal experiments from the Space Lab and Cosmos missions indicate that events that are mediated by cyclic AMP, such as cellular responses to catecholamine and peptide hormone action, are significantly altered in a number of tissues as a consequence of space flight. A secretory cyclic AMP-receptor protein (cARP), is present in saliva, and can serve as an indicator of individual responses to physiologic and environmental stress. Animal experiments have shown that the hypergravity component of space flight is a significant stress factor. In humans, cARP levels in each individual are constant under normal conditions, but elevated after acute stress. Additionally, the levels of cARP in secreted saliva can be compared to those in gingival crevicular fluid (GCF), which reflects the protein composition of serum. The ratio of cARP in saliva to that in GCF can be used as a measure of basal compared to hyper-or hypo-gravity values. An ultimate goal is to test hyper and zero G responses in human saliva to determine if cARP is a suitable index of acute and chronic stress. A miniaturized test kit for saliva collection has been designed. Samples can be collected and stored till analyses are carried out that will distinguish the effects of increased gravity from those of one and zero G. Such tests can serve as an individualized monitoring system for physiologic responses either in space or on earth. .

  16. Reconstitution of actin-based motility of Listeria and Shigella using pure proteins

    NASA Astrophysics Data System (ADS)

    Loisel, Thomas P.; Boujemaa, Rajaa; Pantaloni, Dominique; Carlier, Marie-France

    1999-10-01

    Actin polymerization is essential for cell locomotion and is thought to generate the force responsible for cellular protrusions. The Arp2/3 complex is required to stimulate actin assembly at the leading edge in response to signalling. The bacteria Listeria and Shigella bypass the signalling pathway and harness the Arp2/3 complex to induce actin assembly and to propel themselves in living cells. However, the Arp2/3 complex alone is insufficient to promote movement. Here we have used pure components of the actin cytoskeleton to reconstitute sustained movement in Listeria and Shigella in vitro. Actin-based propulsion is driven by the free energy released by ATP hydrolysis linked to actin polymerization, and does not require myosin. In addition to actin and activated Arp2/3 complex, actin depolymerizing factor (ADF, or cofilin) and capping protein are also required for motility as they maintain a high steady-state level of G-actin, which controls the rate of unidirectional growth of actin filaments at the surface of the bacterium. The movement is more effective when profilin, α-actinin and VASP (for Listeria) are also included. These results have implications for our understanding of the mechanism of actin-based motility in cells.

  17. An Operational Configuration of the ARPS Data Analysis System to Initialize WRF in the NM'S Environmental Modeling System

    NASA Technical Reports Server (NTRS)

    Case, Jonathan; Blottman, Pete; Hoeth, Brian; Oram, Timothy

    2006-01-01

    The Weather Research and Forecasting (WRF) model is the next generation community mesoscale model designed to enhance collaboration between the research and operational sectors. The NM'S as a whole has begun a transition toward WRF as the mesoscale model of choice to use as a tool in making local forecasts. Currently, both the National Weather Service in Melbourne, FL (NWS MLB) and the Spaceflight Meteorology Group (SMG) are running the Advanced Regional Prediction System (AIRPS) Data Analysis System (ADAS) every 15 minutes over the Florida peninsula to produce high-resolution diagnostics supporting their daily operations. In addition, the NWS MLB and SMG have used ADAS to provide initial conditions for short-range forecasts from the ARPS numerical weather prediction (NWP) model. Both NM'S MLB and SMG have derived great benefit from the maturity of ADAS, and would like to use ADAS for providing initial conditions to WRF. In order to assist in this WRF transition effort, the Applied Meteorology Unit (AMU) was tasked to configure and implement an operational version of WRF that uses output from ADAS for the model initial conditions. Both agencies asked the AMU to develop a framework that allows the ADAS initial conditions to be incorporated into the WRF Environmental Modeling System (EMS) software. Developed by the NM'S Science Operations Officer (S00) Science and Training Resource Center (STRC), the EMS is a complete, full physics, NWP package that incorporates dynamical cores from both the National Center for Atmospheric Research's Advanced Research WRF (ARW) and the National Centers for Environmental Prediction's Non-Hydrostatic Mesoscale Model (NMM) into a single end-to-end forecasting system. The EMS performs nearly all pre- and postprocessing and can be run automatically to obtain external grid data for WRF boundary conditions, run the model, and convert the data into a format that can be readily viewed within the Advanced Weather Interactive Processing System

  18. Protective Effects of Resveratrol against UVA-Induced Damage in ARPE19 Cells

    PubMed Central

    Chan, Chi-Ming; Huang, Cheng-Hua; Li, Hsin-Ju; Hsiao, Chien-Yu; Su, Ching-Chieh; Lee, Pei-Lan; Hung, Chi-Feng

    2015-01-01

    Ultraviolet radiation, especially UVA, can penetrate the lens, reach the retina, and induce oxidative stress to retinal pigment epithelial (RPE) cells. Even though it is weakly absorbed by protein and DNA, it may trigger the production of reactive oxygen species (ROS) and generate oxidative injury; oxidative injury to the retinal pigment epithelium has been implicated to play a contributory role in age-related macular degeneration (AMD). Studies showed that resveratrol, an abundant and active component of red grapes, can protect several cell types from oxidative stress. In this study, adult RPE cells being treated with different concentrations of resveratrol were used to evaluate the protective effect of resveratrol on RPE cells against UVA-induced damage. Cell viability assay showed that resveratrol reduced the UVA-induced decrease in RPE cell viability. Through flow cytometry analysis, we found that the generation of intracellular H2O2 induced by UVA irradiation in RPE cells could be suppressed by resveratrol in a concentration-dependent manner. Results of Western blot analysis demonstrated that resveratrol lowered the activation of UVA-induced extracellular signal-regulated kinase, c-jun-NH2 terminal kinase and p38 kinase in RPE cells. In addition, there was also a reduction in UVA-induced cyclooxygenase-2 (COX-2) expression in RPE cells pretreated with resveratrol. Our observations suggest that resveratrol is effective in preventing RPE cells from being damaged by UVA radiation, and is worth considering for further development as a chemoprotective agent for the prevention of early AMD. PMID:25775159

  19. Protective effects of resveratrol against UVA-induced damage in ARPE19 cells.

    PubMed

    Chan, Chi-Ming; Huang, Cheng-Hua; Li, Hsin-Ju; Hsiao, Chien-Yu; Su, Ching-Chieh; Lee, Pei-Lan; Hung, Chi-Feng

    2015-01-01

    Ultraviolet radiation, especially UVA, can penetrate the lens, reach the retina, and induce oxidative stress to retinal pigment epithelial (RPE) cells. Even though it is weakly absorbed by protein and DNA, it may trigger the production of reactive oxygen species (ROS) and generate oxidative injury; oxidative injury to the retinal pigment epithelium has been implicated to play a contributory role in age-related macular degeneration (AMD). Studies showed that resveratrol, an abundant and active component of red grapes, can protect several cell types from oxidative stress. In this study, adult RPE cells being treated with different concentrations of resveratrol were used to evaluate the protective effect of resveratrol on RPE cells against UVA-induced damage. Cell viability assay showed that resveratrol reduced the UVA-induced decrease in RPE cell viability. Through flow cytometry analysis, we found that the generation of intracellular H2O2 induced by UVA irradiation in RPE cells could be suppressed by resveratrol in a concentration-dependent manner. Results of Western blot analysis demonstrated that resveratrol lowered the activation of UVA-induced extracellular signal-regulated kinase, c-jun-NH2 terminal kinase and p38 kinase in RPE cells. In addition, there was also a reduction in UVA-induced cyclooxygenase-2 (COX-2) expression in RPE cells pretreated with resveratrol. Our observations suggest that resveratrol is effective in preventing RPE cells from being damaged by UVA radiation, and is worth considering for further development as a chemoprotective agent for the prevention of early AMD. PMID:25775159

  20. Morphology and Kinematics of Warm Molecular Gas in the Nuclear Region of Arp 220 as Revealed by ALMA

    NASA Astrophysics Data System (ADS)

    Rangwala, Naseem; Maloney, Philip R.; Wilson, Christine D.; Glenn, Jason; Kamenetzky, Julia; Spinoglio, Luigi

    2015-06-01

    We present Atacama Large Millimeter Array (ALMA) Cycle-0 observations of the CO J = 6-5 line in the advanced galaxy merger Arp 220. This line traces warm molecular gas, which dominates the total CO luminosity. The CO emission from the two nuclei is well resolved by the 0\\buildrel{\\prime\\prime}\\over{.} 39× 0\\buildrel{\\prime\\prime}\\over{.} 22 beam and the exceptional sensitivity and spatial/spectral resolution reveal new complex features in the morphology and kinematics of the warm gas. The line profiles are asymmetric between the red and blue sides of the nuclear disks and the peak of the line emission is offset from the peak of the continuum emission in both nuclei by about 100 pc in the same direction. CO self-absorption is detected at the centers of both nuclei but it is much deeper in the eastern nucleus. We also clearly detect strong, highly redshifted CO absorption located near the southwest side of each nucleus. For the eastern nucleus, we reproduce the major line profile features with a simple kinematic model of a highly turbulent, rotating disk with a substantial line center optical depth and a large gradient in the excitation temperature. The red/blue asymmetries and line-to-continuum offset are likely produced by absorption of the blue (SW) sides of the two nuclei by blueshifted, foreground molecular gas; the mass of the absorber is comparable to the nuclear warm gas mass (˜{{10}8} {{M}⊙ }). We measure an unusually high {{L}CO}/{{L}FIR} ratio in the eastern nucleus, suggesting there is an additional energy source, such as mechanical energy from shocks, present in this nucleus.

  1. Valence Band Character of NiS2-xSex using 3p-3d Resonant ARPES

    NASA Astrophysics Data System (ADS)

    Han, Garam; Kim, Yeongkwan; Koh, Yoonyoung; Kim, Beomyoung; Song, Dongjoon; Seo, Jungjin; Kyung, Wonshik; Lee, Kyungdong; Kim, Changyoung

    2013-03-01

    Understanding the strong correlated system is one of the most challenging tasks in condensed matter physics. Especially, the metal insulator transition (MIT) has been one of the major topics recent few decades. NiS2-xSex is known as one of famous material which has MIT. The cubic pyrite NiS2 is a charge-transfer (CT) insulator. NiS2 attracts particular interest as it easily forms a solid solution with NiSe2 (NiS2-xSex) which, while being isoelectronic and isostructural to NiS2, is nevertheless a good metal. MIT, induced by Se alloying, is observed at low temperature (T) for x =0.45. Perucchi and his collaborators revealed closed relation between MIT and band width through comparison of infrared spectroscopy result and LDA calculation. However, it was only an indirect observation, and is inconsistent with recent proposal that NiS2 is not a CT insulator but an insulator due to the bonding-antibonding splitting in the S - S (Se - Se) dimers. To reveal the true mechanism in the MIT in NiS2-xSex, resonant photoemission experiment is essential. According to competing theories (CT insulator and insulator due to bonding-antibonding splitting), it is expected that the character of the main band that is responsible for the MIT should be different. Therefore, we performed 3p->3d resonant ARPES for various Se dopings (x =0.43; insulator, x =0.5, 0.7, 2.0; metal) and observed a significant change between on- and off-resonances near the MIT. Our experimental result supports that the origin of MIT in NiS2-xSex is the CT theory rather than the dimer theory.

  2. Development and Deployment of an Aerospace Recommended Practice (ARP) Compliant Measurement System for nvPM Certification Measurements of Aircraft Engines - Current Status.

    NASA Astrophysics Data System (ADS)

    Whitefield, P. D.; Hagen, D. E.; Lobo, P.; Miake-Lye, R. C.

    2015-12-01

    The Society of Automotive Engineers (SAE) Aircraft Exhaust Emissions Measurement Committee (E-31) has published an Aerospace Information Report (AIR) 6241 detailing the sampling system for the measurement of non-volatile particulate matter (nvPM) from aircraft engines (SAE 2013). The system is designed to operate in parallel with existing International Civil Aviation Organization (ICAO) Annex 16 compliant combustion gas sampling systems used for emissions certification from aircraft engines captured by conventional (Annex 16) gas sampling rakes (ICAO, 2008). The SAE E-31 committee is also working to ballot an Aerospace Recommended Practice (ARP) that will provide the methodology and system specification to measure nvPM from aircraft engines. The ARP is currently in preparation and is expected to be ready for ballot in 2015. A prototype AIR-compliant nvPM measurement system - The North American Reference System (NARS) has been built and evaluated at the MSTCOE under the joint sponsorship of the FAA, EPA and Transport Canada. It has been used to validate the performance characteristics of OEM AIR-compliant systems and is being used in engine certification type testing at OEM facilities to obtain data from a set of representative engines in the fleet. The data collected during these tests will be used by ICAO/CAEP/WG3/PMTG to develop a metric on which on the regulation for nvPM emissions will be based. This paper will review the salient features of the NARS including: (1) emissions sample transport from probe tip to the key diagnostic tools, (2) the mass and number-based diagnostic tools for nvPM mass and number concentration measurement and (3) methods employed to assess the extent of nvPM loss throughout the sampling system. This paper will conclude with a discussion of the recent results from inter-comparison studies conducted with other US - based systems that gives credence to the ARP's readiness for ballot.

  3. ARPES study of the evolution of band structure and charge density wave properties in RTe3 ( R=Y , La, Ce, Sm, Gd, Tb, and Dy)

    SciTech Connect

    Hussain, Zahid; Brouet, Veronique; Yang, Wanli; Zhou, Xingjiang; Hussain, Zahid; Moore, R.G.; He, R.; Lu, D. H.; Shen, Z.X.; Laverock, J.; Dugdale, S.B.; Ru, N.; Fisher, R.

    2008-01-16

    We present a detailed angle-resolved photoemission spectroscopy (ARPES) investigation of the RTe3 family, which sets this system as an ideal"textbook" example for the formation of a nesting driven charge density wave (CDW). This family indeed exhibits the full range of phenomena that can be associated to CDWinstabilities, from the opening of large gaps on the best nested parts of Fermi surface (up to 0.4 eV), to the existence of residual metallic pockets. ARPES is the best suited technique to characterize these features, thanks to its unique ability to resolve the electronic structure in k space. An additional advantage of RTe3 is that theband structure can be very accurately described by a simple two dimensional tight-binding (TB) model, which allows one to understand and easily reproduce many characteristics of the CDW. In this paper, we first establish the main features of the electronic structure by comparing our ARPES measurements with the linear muffin-tinorbital band calculations. We use this to define the validity and limits of the TB model. We then present a complete description of the CDW properties and of their strong evolution as a function of R. Using simple models, we are able to reproduce perfectly the evolution of gaps in k space, the evolution of the CDW wave vector with R, and the shape of the residual metallic pockets. Finally, we give an estimation of the CDWinteraction parameters and find that the change in the electronic density of states n (EF), due to lattice expansion when different R ions are inserted, has the correct order of magnitude to explain the evolution of the CDW properties.

  4. Full-length transcriptome analysis of human retina-derived cell lines ARPE-19 and Y79 using the vector-capping method.

    PubMed

    Oshikawa, Mio; Tsutsui, Chihiro; Ikegami, Tomoko; Fuchida, Yuki; Matsubara, Maki; Toyama, Shigeru; Usami, Ron; Ohtoko, Kuniyo; Kato, Seishi

    2011-08-01

    PURPOSE. To collect an entire set of full-length cDNA clones derived from human retina-derived cell lines and to identify full-length transcripts for retinal preferentially expressed genes. METHODS. The full-length cDNA libraries were constructed from a retinoblastoma cell line, Y79, and a retinal pigment epithelium cell line, ARPE-19, using the vector-capping method, which generates a genuine full-length cDNA. By single-pass sequencing of the 5'-end of cDNA clones and subsequent mapping to the human genome, the authors determined their transcriptional start sites and annotated the cDNA clones. RESULTS. Of the 23,616 clones isolated from Y79-derived cDNA libraries, 19,229 full-length cDNA clones were identified and classified into 4808 genes, including genes of >10 kbp. Of the 7067 genes obtained from the Y79 and ARPE-19 libraries, the authors selected 72 genes that were preferentially expressed in the eye, of which 131 clones corresponding to 57 genes were fully sequenced. As a result, we discovered many variants that were produced by different transcriptional start sites, alternative splicing, and alternative polyadenylation. CONCLUSIONS. The bias-free, full-length cDNA libraries constructed using the vector-capping method were shown to be useful for collecting an entire set of full-length cDNA clones for these retinal cell lines. Full-length transcriptome analysis of these cDNA libraries revealed that there were, unexpectedly, many transcript variants for each gene, indicating that obtaining the full-length cDNA for each variant is indispensable for analyzing its function. The full-length cDNA clones (approximately 80,000 clones each for ARPE-19 and Y79) will be useful as a resource for investigating the human retina. PMID:21697133

  5. A Modification of the Isotope Generation and Depletion Code System ORIGEN. CCC-702/ORIGEN-ARP is recommended for new ORIGEN users.

    1984-05-04

    Version 00 KORIGEN is a modification of the isotope generation and depletion code system CCC-217/ORIGEN. ORIGEN solved the equations of radioactive growth and decay allowing continuous first order chemical processing and a neutron flux described by a three-region spectrum. Complex decay and transmutation schemes were treated. Note that this package has not been updated in many years; and all new ORIGEN users are advised to request the CCC-702/ORIGEN-ARP package, which is a PC application formore » Windows 95/NT or later.« less

  6. Dynactin 3D structure: implications for assembly and dynein binding.

    PubMed

    Imai, Hiroshi; Narita, Akihiro; Maéda, Yuichiro; Schroer, Trina A

    2014-09-23

    The multisubunit protein complex, dynactin, is an essential component of the cytoplasmic dynein motor. High-resolution structural work on dynactin and the dynein/dynactin supercomplex has been limited to small subunits and recombinant fragments that do not report fully on either ≈1MDa assembly. In the present study, we used negative-stain electron microscopy and image analysis based on random conical tilt reconstruction to obtain a three-dimensional (3D) structure of native vertebrate dynactin. The 35-nm-long dynactin molecule has a V-shaped shoulder at one end and a flattened tip at the other end, both offset relative to the long axis of the actin-related protein (Arp) backbone. The shoulder projects dramatically away from the Arp filament core in a way that cannot be appreciated in two-dimensional images, which has implications for the mechanism of dynein binding. The 3D structure allows the helical parameters of the entire Arp filament core, which includes the actin capping protein, CP, to be determined for the first time. This structure exhibits near identity to F-actin and can be well fitted into the dynactin envelope. Molecular fitting of modeled CP-Arp polymers into the envelope shows that the filament contains between 7 and 9 Arp protomers and is capped at both ends. In the 7 Arp model, which agrees best with measured Arp stoichiometry and other structural information, actin capping protein (CP) is not present at the distal tip of the structure, unlike what is seen in the other models. The 3D structure suggests a mechanism for dynactin assembly and length specification. PMID:25046383

  7. Advanced glycation end-product (AGE) induces apoptosis in human retinal ARPE-19 cells via promoting mitochondrial dysfunction and activating the Fas-FasL signaling.

    PubMed

    Wang, Pu; Xing, Yiqiao; Chen, Changzheng; Chen, Zhen; Qian, Zhimin

    2016-01-01

    Advanced glycation end-products (AGEs) are extremely accumulated in the retinal vascular and epithelial cells of diabetes mellitus (DM) patients, particularly with diabetic retinopathy (DR). To elucidate the pathogenesis of the AGE-induced toxicity to retinal epithelial cells, we investigated the role of Fas-Fas ligand (FasL) signaling and mitochondrial dysfunction in the AGE-induced apoptosis. Results demonstrated that the AGE-BSA- induced apoptosis of retinal ARPE-19 cells. And the AGE-BSA treatment caused mitochondrial dysfunction, via deregulating the B-cell lymphoma 2 (Bcl-2) signaling. Moreover, the Fas/FasL and its downstreamer Caspase 8 were promoted by the AGE-BSA treatment, and the exogenous α-Fas exacerbated the activation of Caspase 3/8. On the other side, the siRNA-mediated knockdown of Fas/FasL inhibited the AGE-BSA-induced apoptosis. Taken together, we confirmed the activation of Fas-FasL signaling and of mitochondrial dysfunction in the AGE-BSA-promoted apoptosis in retinal ARPE-19 cells, implying the important role of Fas-FasL signaling in the DR in DM. PMID:26479732

  8. ARPES EVIDENCE FOR A QUASIPARTICLE LIQUID IN OVERDOPED Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+delta}.

    SciTech Connect

    WELLS,B.O.; YUSOF,Z.; VALLA,T.; FEDOROV,A.V.; JOHNSON,P.; KENDZIORA,C.; JIAN,S.; HINKS,D.

    2001-07-23

    High resolution angle-resolved photoemission spectroscopy of highly overdoped Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} with a T{sub c} = 51K indicates that the basic transport processes in this material are fundamentally different from both the lesser doped cuprates as well as model metallic compounds. The overdoped sample has sharp ARPES peaks at the Fermi energy throughout the Brillouin zone even in the normal state, unlike the lesser-doped compounds. In particular, the spectra near ({pi},0) point show the presence of a sharp peak well above T{sub c}. The ARPES lineshapes, and thus the self energy, at a given energy are almost independent of k. Further, the quasiparticle scattering rate at the Fermi energy seems to be closely tied to direct resistivity measurements. This leads us to the conclusion that overdoped Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} is best described as a quasiparticle liquid. However, the energy dependence of the scattering rates is quite similar to that found in the lesser-doped compounds and quite different from that seen in a typical metal.

  9. Acidic Nanoparticles Are Trafficked to Lysosomes and Restore an Acidic Lysosomal pH and Degradative Function to Compromised ARPE-19 Cells

    PubMed Central

    Baltazar, Gabriel C.; Guha, Sonia; Lu, Wennan; Lim, Jason; Boesze-Battaglia, Kathleen; Laties, Alan M.; Tyagi, Puneet; Kompella, Uday B.; Mitchell, Claire H.

    2012-01-01

    Lysosomal enzymes function optimally in acidic environments, and elevation of lysosomal pH can impede their ability to degrade material delivered to lysosomes through autophagy or phagocytosis. We hypothesize that abnormal lysosomal pH is a key aspect in diseases of accumulation and that restoring lysosomal pH will improve cell function. The propensity of nanoparticles to end up in the lysosome makes them an ideal method of delivering drugs to lysosomes. This study asked whether acidic nanoparticles could traffic to lysosomes, lower lysosomal pH and enhance lysosomal degradation by the cultured human retinal pigmented epithelial cell line ARPE-19. Acidic nanoparticles composed of poly (DL-lactide-co-glycolide) (PLGA) 502 H, PLGA 503 H and poly (DL-lactide) (PLA) colocalized to lysosomes of ARPE-19 cells within 60 min. PLGA 503 H and PLA lowered lysosomal pH in cells compromised by the alkalinizing agent chloroquine when measured 1 hr. after treatment, with acidification still observed 12 days later. PLA enhanced binding of Bodipy-pepstatin-A to the active site of cathepsin D in compromised cells. PLA also reduced the cellular levels of opsin and the lipofuscin-like autofluorescence associated with photoreceptor outer segments. These observations suggest the acidification produced by the nanoparticles was functionally effective. In summary, acid nanoparticles lead to a rapid and sustained lowering of lysosomal pH and improved degradative activity. PMID:23272048

  10. Quantitative measurements and modeling of electronic and atomic surface structure in epitaxial LaNiO3 thin films by ARPES, LEED-I(V), and DFT +DMFT

    NASA Astrophysics Data System (ADS)

    Ruf, Jacob; Nowadnick, Elizabeth; Park, Hyowon; King, Philip; Millis, Andrew; Schlom, Darrell; Shen, Kyle

    Careful exploration of the phase space available for artificially engineering emergent electronic properties in epitaxial thin films and superlattices of transition-metal oxides requires close feedback between materials synthesis, experimental characterization of both electronic and atomic structures, and modeling based on advanced computational methods. Here we apply this general strategy to the perovskite rare-earth nickelate LaNiO3, using molecular-beam epitaxy to synthesize thin films, performing in situangle-resolved photoemission spectroscopy (ARPES) and low-energy electron diffraction (LEED) measurements, and comparing our results with the predictions of density functional theory plus dynamical mean-field theory (DFT +DMFT). Our study establishes LaNiO3 as a moderately correlated metal in which the quasiparticle mass enhancement can be modeled with quantitative accuracy by DFT +DMFT. Finally, in view of efforts to produce eg orbital polarization in nickelate heterostructures as a means of mimicking single-band cuprate-like physics, we discuss the extent to which our ARPES and LEED results suggest that such effects are intrinsically present at film surfaces due to the existence of polar distortions, as reported by coherent Bragg rod analysis of surface x-ray diffraction.

  11. On the multiple supernova population of Arp 299: constraints on progenitor properties and host galaxy star formation characteristics

    NASA Astrophysics Data System (ADS)

    Anderson, J. P.; Habergham, S. M.; James, P. A.

    2011-09-01

    Arp 299 is an interacting system of two components: NGC 3690 and IC 694. Throughout the last 20 years seven supernovae have been catalogued as being discovered within the system. One of these is unclassified, leaving six core-collapse supernovae: two type II (one with IIL subtype classification); two type Ib events; a type IIb supernova; and an object of indistinct type, Ib/IIb. We analyse the relative numbers of these supernova types, together with their relative positions with respect to host galaxy properties, to investigate the implications for both progenitor characteristics and host galaxy star formation properties. Our main findings are as follows. (1) the ratio of 'stripped envelope' supernovae (types Ib and IIb) to other 'normal' type II is higher than that found in the local Universe. There is ˜10 per cent probability that the observed supernova type ratio is drawn from an underlying distribution such as that found in galaxies in the local Universe. (2) All 'stripped envelope' supernovae are more centrally concentrated within the system than the other type II (˜7 per cent chance probability). (3) All supernova environments have similar derived metallicities and there are no significant metallicity gradients found across the system. (4) The 'stripped envelope' supernovae all fall on regions of Hα emission while the other type II are found to occur away from bright H II regions (again, ˜7 per cent chance probability). From this investigation we draw two different - but non-mutually exclusive - interpretations on the system and its supernovae as follows. (1) The distribution of supernovae, and the relatively high fraction of types Ib and IIb events over other type II can be explained by the young age of the most recent star formation in the system, where insufficient time has expired for the observed to match the 'true' relative supernova rates. If this explanation is valid then the present study provides additional (independent) evidence that both types

  12. All-Trans Retinoic Acid Modulates DNA Damage Response and the Expression of the VEGF-A and MKI67 Genes in ARPE-19 Cells Subjected to Oxidative Stress

    PubMed Central

    Tokarz, Paulina; Piastowska-Ciesielska, Agnieszka Wanda; Kaarniranta, Kai; Blasiak, Janusz

    2016-01-01

    Age-related macular degeneration (AMD) is characterized by the progressive degradation of photoreceptors and retinal pigment epithelium (RPE) cells. ARPE-19 is an RPE cell line established as an in vitro model for the study of AMD pathogenesis. Oxidative stress is an AMD pathogenesis factor that induces DNA damage. Thus, the oxidative stress-mediated DNA damage response (DDR) of ARPE-19 cells can be important in AMD pathogenesis. The metabolism of retinoids—which regulates cell proliferation, differentiation, and the visual cycle in the retina—was reported to be disturbed in AMD patients. In the present work, we studied the effect of all-trans retinoic acid (ATRA, a retinoid) on DDR in ARPE-19 cells subjected to oxidative stress. We observed that ATRA increased the level of reactive oxygen species (ROS), alkali-labile sites in DNA, DNA single-strand breaks, and cell death evoked by oxidative stress. ATRA did not modulate DNA repair or the distribution of cells in cell cycle in the response of ARPE-19 cells to oxidative stress. ATRA induced autophagy in the absence of oxidative stress, but had no effect on this process in the stress. ATRA induced over-expression of proliferation marker MKI67 and neovascularization marker VEGF-A. In conclusion, ATRA increased oxidative stress in ARPE-19 cells, resulting in more lesions to their DNA and cell death. Moreover, ATRA can modulate some properties of these cells, including neovascularization, which is associated with the exudative form of AMD. Therefore, ATRA can be important in the prevention, diagnosis, and therapy of AMD. PMID:27314326

  13. All-Trans Retinoic Acid Modulates DNA Damage Response and the Expression of the VEGF-A and MKI67 Genes in ARPE-19 Cells Subjected to Oxidative Stress.

    PubMed

    Tokarz, Paulina; Piastowska-Ciesielska, Agnieszka Wanda; Kaarniranta, Kai; Blasiak, Janusz

    2016-01-01

    Age-related macular degeneration (AMD) is characterized by the progressive degradation of photoreceptors and retinal pigment epithelium (RPE) cells. ARPE-19 is an RPE cell line established as an in vitro model for the study of AMD pathogenesis. Oxidative stress is an AMD pathogenesis factor that induces DNA damage. Thus, the oxidative stress-mediated DNA damage response (DDR) of ARPE-19 cells can be important in AMD pathogenesis. The metabolism of retinoids-which regulates cell proliferation, differentiation, and the visual cycle in the retina-was reported to be disturbed in AMD patients. In the present work, we studied the effect of all-trans retinoic acid (ATRA, a retinoid) on DDR in ARPE-19 cells subjected to oxidative stress. We observed that ATRA increased the level of reactive oxygen species (ROS), alkali-labile sites in DNA, DNA single-strand breaks, and cell death evoked by oxidative stress. ATRA did not modulate DNA repair or the distribution of cells in cell cycle in the response of ARPE-19 cells to oxidative stress. ATRA induced autophagy in the absence of oxidative stress, but had no effect on this process in the stress. ATRA induced over-expression of proliferation marker MKI67 and neovascularization marker VEGF-A. In conclusion, ATRA increased oxidative stress in ARPE-19 cells, resulting in more lesions to their DNA and cell death. Moreover, ATRA can modulate some properties of these cells, including neovascularization, which is associated with the exudative form of AMD. Therefore, ATRA can be important in the prevention, diagnosis, and therapy of AMD. PMID:27314326

  14. Common Origin of the Circular-dichroism Pattern in ARPES of SrTiO3 and CuxBi2Se3

    SciTech Connect

    Bell, Christopher

    2011-08-19

    We investigate circular dichroism in the angular distribution (CDAD) of photoelectrons from SrTiO{sub 3}:Nb and Cu{sub x}Bi{sub 2}Se{sub 3} recorded by 7-eV laser ARPES. In addition to the well-known node that occurs in CDAD when the incidence plane matches the mirror plane of the crystal, we show that another type of node occurs when the mirror plane of the crystal is vertical to the incidence plane and the electronic state is two dimensional. The flower-shaped CDAD's occurring around the Fermi level of SrTiO{sub 3}:Nb and around the Dirac point of Cu{sub x}Bi{sub 2}Se{sub 3} are explained on equal footings. A surface-state-to-surface-resonance transition is indicated for the topological state of Cu{sub x}Bi{sub 2}Se{sub 3}.

  15. OBSERVATIONS OF Arp 220 USING HERSCHEL-SPIRE: AN UNPRECEDENTED VIEW OF THE MOLECULAR GAS IN AN EXTREME STAR FORMATION ENVIRONMENT

    SciTech Connect

    Rangwala, Naseem; Maloney, Philip R.; Glenn, Jason; Kamenetzky, Julia; Wilson, Christine D.; Mentuch, Erin; Schirm, Maximilien R. P.; Rykala, Adam; Isaak, Kate; Baes, Maarten; Bendo, George J.; Boselli, Alessandro; Bradford, Charles M.; Clements, D. L.; Cooray, Asantha; Fulton, Trevor; Imhof, Peter; Madden, Suzanne C.; Sauvage, Marc; and others

    2011-12-10

    We present Herschel Spectral and Photometric Imaging Receiver Fourier Transform Spectrometer (Herschel SPIRE-FTS) observations of Arp 220, a nearby ultra-luminous infrared galaxy. The FTS provides continuous spectral coverage from 190 to 670 {mu}m, a wavelength region that is either very difficult to observe or completely inaccessible from the ground. The spectrum provides a good measurement of the continuum and detection of several molecular and atomic species. We detect luminous CO (J = 4-3 to 13-12) and water rotational transitions with comparable total luminosity {approx}2 Multiplication-Sign 10{sup 8} L{sub Sun }; very high-J transitions of HCN (J = 12-11 to 17-16) in absorption; strong absorption features of rare species such as OH{sup +}, H{sub 2}O{sup +}, and HF; and atomic lines of [C I] and [N II]. The modeling of the continuum shows that the dust is warm, with T = 66 K, and has an unusually large optical depth, with {tau}{sub dust} {approx} 5 at 100 {mu}m. The total far-infrared luminosity of Arp 220 is L{sub FIR} {approx} 2 Multiplication-Sign 10{sup 12} L{sub Sun }. Non-LTE modeling of the extinction corrected CO rotational transitions shows that the spectral line energy distribution of CO is fit well by two temperature components: cold molecular gas at T {approx} 50 K and warm molecular gas at T {approx} 1350{sup +280}{sub -100} K (the inferred temperatures are much lower if CO line fluxes are not corrected for dust extinction). These two components are not in pressure equilibrium. The mass of the warm gas is 10% of the cold gas, but it dominates the CO luminosity. The ratio of total CO luminosity to the total FIR luminosity is L{sub CO}/L{sub FIR} {approx} 10{sup -4} (the most luminous lines, such as J = 6-5, have L{sub CO,J=6-5}/L{sub FIR} {approx} 10{sup -5}). The temperature of the warm gas is in excellent agreement with the observations of H{sub 2} rotational lines. At 1350 K, H{sub 2} dominates the cooling ({approx}20 L{sub Sun} M{sup -1}{sub

  16. Observations of Arp 220 Using Herschel-SPIRE: An Unprecedented View of the Molecular Gas in an Extreme Star Formation Environment

    NASA Astrophysics Data System (ADS)

    Rangwala, Naseem; Maloney, Philip R.; Glenn, Jason; Wilson, Christine D.; Rykala, Adam; Isaak, Kate; Baes, Maarten; Bendo, George J.; Boselli, Alessandro; Bradford, Charles M.; Clements, D. L.; Cooray, Asantha; Fulton, Trevor; Imhof, Peter; Kamenetzky, Julia; Madden, Suzanne C.; Mentuch, Erin; Sacchi, Nicola; Sauvage, Marc; Schirm, Maximilien R. P.; Smith, M. W. L.; Spinoglio, Luigi; Wolfire, Mark

    2011-12-01

    We present Herschel Spectral and Photometric Imaging Receiver Fourier Transform Spectrometer (Herschel SPIRE-FTS) observations of Arp 220, a nearby ultra-luminous infrared galaxy. The FTS provides continuous spectral coverage from 190 to 670 μm, a wavelength region that is either very difficult to observe or completely inaccessible from the ground. The spectrum provides a good measurement of the continuum and detection of several molecular and atomic species. We detect luminous CO (J = 4-3 to 13-12) and water rotational transitions with comparable total luminosity ~2 × 108 L ⊙ very high-J transitions of HCN (J = 12-11 to 17-16) in absorption; strong absorption features of rare species such as OH+, H2O+, and HF; and atomic lines of [C I] and [N II]. The modeling of the continuum shows that the dust is warm, with T = 66 K, and has an unusually large optical depth, with τdust ~ 5 at 100 μm. The total far-infrared luminosity of Arp 220 is L FIR ~ 2 × 1012 L ⊙. Non-LTE modeling of the extinction corrected CO rotational transitions shows that the spectral line energy distribution of CO is fit well by two temperature components: cold molecular gas at T ~ 50 K and warm molecular gas at T ~ 1350+280 - 100 K (the inferred temperatures are much lower if CO line fluxes are not corrected for dust extinction). These two components are not in pressure equilibrium. The mass of the warm gas is 10% of the cold gas, but it dominates the CO luminosity. The ratio of total CO luminosity to the total FIR luminosity is L CO/L FIR ~ 10-4 (the most luminous lines, such as J = 6-5, have L CO, J = 6-5/L FIR ~ 10-5). The temperature of the warm gas is in excellent agreement with the observations of H2 rotational lines. At 1350 K, H2 dominates the cooling (~20 L ⊙ M -1 ⊙) in the interstellar medium compared to CO (~0.4 L ⊙ M -1 ⊙). We have ruled out photodissociation regions, X-ray-dominated regions, and cosmic rays as likely sources of excitation of this warm molecular gas

  17. Phase Diagram and High Temperature Superconductivity at 65K in the Single-Layer FeSe Films Revealed by ARPES

    NASA Astrophysics Data System (ADS)

    He, Shaolong

    2013-03-01

    The discovery of the iron-based superconductors in 2008 not only provides another venue to understand the origin of high-Tc superconductivity but also a new playground to explore novel superconductors with higher superconducting transition temperature. The latest report of possible high temperature superconductivity in the single-layer FeSe films grown on SrTiO3 substrate is both surprising and interesting. In this talk, we report the electronic structure and phase diagram of the single-layer FeSe films by angle-resolved photoemission spectroscopy (ARPES). Our high-resolution ARPES results show that it has a simple Fermi surface topology consisting only of electron pockets near the zone corner without indication of any Fermi surface around the zone center. In addition, our observation of large and nearly isotropic superconducting gap in this strictly two-dimensional system rules out existence of node in the superconducting gap. We also established a phase diagram in this single-layer FeSe films by an annealing procedure to tune the charge carrier concentration over a wide range. By optimizing the annealing process, we observed evidence of a record high Tc of ~ 65K in the single-layer FeSe films. The wide tunability of the system across different phases, and its high-Tc, make the single-layer FeSe film ideal not only to investigate the superconductivity physics and mechanism, but also to study novel quantum phenomena and for potential applications. Work done in collaboration with J. He, W. Zhang, L. Zhao, D. Liu, X. Liu, D. Mou, Y. Ou, Q. Wang, Z. Li, L. Wang, Y. Peng, Y. Liu, C. Chen, L. Yu, G. Liu, X. Dong, J. Zhang, C. Chen, Z. Xu, X. Chen, X. Ma, Q.-K. Xue, and X. J. Zhou in IOP, CAS, and Tsinghua Univ., Beijing

  18. Analysis and implementation of PM sampling methodology protocols to aid in the development of an ARP (aerospace recommended practice) for aircraft non-volatile PM measurements

    NASA Astrophysics Data System (ADS)

    Catron, Brian Lowell

    Due to the growing concerns that particulate matter (PM) have on health and the environment, there is a need to include mass and number non-volatile PM measurements to current jet engine certification. This thesis looks at the necessary work required to help produce recommendations and perform background research to aid in the creation of an improved Aerospace Recommended Practice (ARP) (by the SAE E-31 Committee). This work addressed the following issues. The investigation began in the Missouri S&T Center of Excellence for Aerospace Particulate Emissions Reduction Research (COE) laboratory with an examination of the jet engine surrogate used, the miniCAST, as well as integrating it into the COE's PM measurement system. A clean PM sample line was aged by running a PM source through it until a steady state signal was measured by the instruments in order to make a recommended procedure for line conditioning as well as reconditioning. Several eductors were studied for their performance characteristics and compared against desired characteristics, which suggested a need to include a pressure relief valve to cap the sample pressure at the eductor entrance. A volatile particle remover (VPR) was studied for penetration and ability to remove volatile material. A prototype E-31 system was setup at the second alternative aviation fuel experiment (AAFEX II), which provided a direct comparison of probe tip dilution and downstream dilution and found comparable results when line loss was taken into account. Also performed at AAFEX II was a study that compared measured sample line penetration with theoretical calculations finding that theoretical calculations were an accurate alternative of measuring line loss. Two PM sampling systems were setup at an ARP demonstration and both system had similar results for both number and mass measurement. An instrument comparison was also performed that included an examination of condensation particle counter (CPC) cutoff size. It was also

  19. Formation of an actin-like filament concurrent with the enzymatic synthesis of inorganic polyphosphate

    PubMed Central

    Gómez-García, María R.; Kornberg, Arthur

    2004-01-01

    Inorganic polyphosphate (poly P), a chain of hundreds of phosphate residues linked by ATP-like bonds, is found in every cell in nature and is commonly produced from ATP by poly P kinases (e.g., PPK1). Dictyostelium discoideum, the social slime mold, possesses a PPK activity (DdPPK1) with sequence similarity to bacterial PPKs. We find here a previously unrecognized PPK (DdPPK2) in D. discoideum with the sequences and properties of actin-related proteins (Arps) that are similar to muscle actins in size, properties, and globular-filamentous structural transitions. Significantly, the unique actin inhibitors, phalloidin and DNase I, also inhibit synthesis of poly P by DdPPK2. Thus, this particular Arp complex is an enzyme that can polymerize into an actin-like filament concurrent with its synthesis of a poly P chain in a fully reversible reaction. PMID:15496465

  20. Mitochondrial "movement" and lens optics following oxidative stress from UV-B irradiation: cultured bovine lenses and human retinal pigment epithelial cells (ARPE-19) as examples.

    PubMed

    Bantseev, Vladimir; Youn, Hyun-Yi

    2006-12-01

    Mitochondria provide energy generated by oxidative phosphorylation and at the same time play a central role in apoptosis and aging. As a byproduct of respiration, the electron transport chain is known to be the major intracellular site for the generation of reactive oxygen species (ROS). Exposure to solar and occupational ultraviolet (UV) radiation, and thus production of ROS and subsequent cell death, has been implicated in a large spectrum of skin and ocular pathologies, including cataract. Retinal pigment epithelial cell apoptosis generates photoreceptor dysfunction and ultimately visual impairment. The purpose of this article was to characterize in vitro changes following oxidative stress with UV-B radiation in (a) ocular lens optics and cellular function in terms of mitochondrial dynamics of bovine lens epithelium and superficial cortical fiber cells and (b) human retinal pigment epithelial (ARPE-19) cells. Cultured bovine lenses and confluent cultures of ARPE-19 cells were irradiated with broadband UV-B radiation at energy levels of 0.5 and 1.0 J/cm(2). Lens optical function (spherical aberration) was monitored daily up to 14 days using an automated laser scanning system that was developed at the University of Waterloo. This system consists of a single collimated scanning helium-neon laser source that projects a thin (0.05 mm) laser beam onto a plain mirror mounted at 45 degrees on a carriage assembly. This mirror reflects the laser beam directly up through the scanner table surface and through the lens under examination. A digital camera captures the actual position and slope of the laser beam at each step. When all steps have been made, the captured data for each step position is used to calculate the back vertex distance for each position and the difference in that measurement between beams. To investigate mitochondrial movement, the mitochondria-specific fluorescent dye Rhodamine 123 was used. Time series were acquired with a Zeiss 510 (configuration Meta

  1. COMMIX-1AR/P: A three-dimensional transient single-phase computer program for thermal hydraulic analysis of single and multicomponent systems. Volume 2, User`s guide

    SciTech Connect

    Garner, P.L.; Blomquist, R.N.; Gelbard, E.M.

    1992-09-01

    The COMMIX-1AR/P computer program is designed for analyzing the steady-state and transient aspects of single-phase fluid flow and heat transfer in three spatial dimensions. This version is an extension of the modeling in COMMIX-1A to include multiple fluids in physically separate regions of the computational domain, modeling descriptions for pumps, radiation heat transfer between surfaces of the solids which are embedded in or surround the fluid, a k-{var_epsilon} model for fluid turbulence, and improved numerical techniques. The porous-medium formulation in COMMIX allows the program to be applied to a wide range of problems involving both simple and complex geometrical arrangements. The input preparation and execution procedures are presented for the COMMIX-1AR/P program and several postprocessor programs which produce graphical displays of the calculated results.

  2. Osmotic stress-induced remodeling of the cortical cytoskeleton.

    PubMed

    Di Ciano, Caterina; Nie, Zilin; Szászi, Katalin; Lewis, Alison; Uruno, Takehito; Zhan, Xi; Rotstein, Ori D; Mak, Alan; Kapus, András

    2002-09-01

    Osmotic stress is known to affect the cytoskeleton; however, this adaptive response has remained poorly characterized, and the underlying signaling pathways are unexplored. Here we show that hypertonicity induces submembranous de novo F-actin assembly concomitant with the peripheral translocation and colocalization of cortactin and the actin-related protein 2/3 (Arp2/3) complex, which are key components of the actin nucleation machinery. Additionally, hyperosmolarity promotes the association of cortactin with Arp2/3 as revealed by coimmunoprecipitation. Using various truncation or phosphorylation-incompetent mutants, we show that cortactin translocation requires the Arp2/3- or the F-actin binding domain, but the process is independent of the shrinkage-induced tyrosine phosphorylation of cortactin. Looking for an alternative signaling mechanism, we found that hypertonicity stimulates Rac and Cdc42. This appears to be a key event in the osmotically triggered cytoskeletal reorganization, because 1) constitutively active small GTPases translocate cortactin, 2) Rac and cortactin colocalize at the periphery of hypertonically challenged cells, and 3) dominant-negative Rac and Cdc42 inhibit the hypertonicity-provoked cortactin and Arp3 translocation. The Rho family-dependent cytoskeleton remodeling may be an important osmoprotective response that reinforces the cell cortex. PMID:12176742

  3. Arabidopsis CROOKED encodes for the smallest subunit of the ARP2/3 complex and controls cell shape by region specific fine F-actin formation.

    PubMed

    Mathur, Jaideep; Mathur, Neeta; Kirik, Victor; Kernebeck, Birgit; Srinivas, Bhylahalli Purushottam; Hülskamp, Martin

    2003-07-01

    The generation of a specific cell shape requires differential growth, whereby specific regions of the cell expand more relative to others. The Arabidopsis crooked mutant exhibits aberrant cell shapes that develop because of mis-directed expansion, especially during a rapid growth phase. GFP-aided visualization of the F-actin cytoskeleton and the behavior of subcellular organelles in different cell-types in crooked and wild-type Arabidopsis revealed that localized expansion is promoted in cellular regions with fine F-actin arrays but is restricted in areas that maintain dense F-actin. This suggested that a spatiotemporal distinction between fine versus dense F-actin in a growing cell could determine the final shape of the cell. CROOKED was molecularly identified as the plant homolog of ARPC5, the smallest sub-unit of the ARP2/3 complex that in other organisms is renowned for its role in creating dendritic arrays of fine F-actin. Rescue of crooked phenotype by the human ortholog provides the first molecular evidence for the presence and functional conservation of the complex in higher plants. Our cell-biological and molecular characterization of CROOKED suggests a general actin-based mechanism for regulating differential growth and generating cell shape diversity. PMID:12783786

  4. Lipoamide Acts as an Indirect Antioxidant by Simultaneously Stimulating Mitochondrial Biogenesis and Phase II Antioxidant Enzyme Systems in ARPE-19 Cells.

    PubMed

    Zhao, Lin; Liu, Zhongbo; Jia, Haiqun; Feng, Zhihui; Liu, Jiankang; Li, Xuesen

    2015-01-01

    In our previous study, we found that pretreatment with lipoamide (LM) more effectively than alpha-lipoic acid (LA) protected retinal pigment epithelial (RPE) cells from the acrolein-induced damage. However, the reasons and mechanisms for the greater effect of LM than LA are unclear. We hypothesize that LM, rather than the more direct antioxidant LA, may act more as an indirect antioxidant. In the present study, we treated ARPE-19 cells with LA and LM and compared their effects on activation of mitochondrial biogenesis and induction of phase II enzyme systems. It is found that LM is more effective than LA on increasing mitochondrial biogenesis and inducing the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its translocation to the nucleus, leading to an increase in expression or activity of phase II antioxidant enzymes (NQO-1, GST, GCL, catalase and Cu/Zn SOD). Further study demonstrated that mitochondrial biogenesis and phase II enzyme induction are closely coupled via energy requirements. These results suggest that LM, compared with the direct antioxidant LA, plays its protective effect on oxidative damage more as an indirect antioxidant to simultaneously stimulate mitochondrial biogenesis and induction of phase II antioxidant enzymes. PMID:26030919

  5. Selective activation of p120ctn-Kaiso signaling to unlock contact inhibition of ARPE-19 cells without epithelial-mesenchymal transition.

    PubMed

    Chen, Hung-Chi; Zhu, Ying-Ting; Chen, Szu-Yu; Tseng, Scheffer C G

    2012-01-01

    Contact-inhibition ubiquitously exists in non-transformed cells and explains the poor regenerative capacity of in vivo human retinal pigment epithelial cells (RPE) during aging, injury and diseases. RPE injury or degeneration may unlock mitotic block mediated by contact inhibition but may also promote epithelial-mesenchymal transition (EMT) contributing to retinal blindness. Herein, we confirmed that EMT ensued in post-confluent ARPE-19 cells when contact inhibition was disrupted with EGTA followed by addition of EGF and FGF-2 because of activation of canonical Wnt and Smad/ZEB signaling. In contrast, knockdown of p120-catenin (p120) unlocked such mitotic block by activating p120/Kaiso, but not activating canonical Wnt and Smad/ZEB signaling, thus avoiding EMT. Nuclear BrdU labeling was correlated with nuclear release of Kaiso through p120 nuclear translocation, which was associated with activation of RhoA-ROCK signaling, destabilization of microtubules. Prolonged p120 siRNA knockdown followed by withdrawal further expanded RPE into more compact monolayers with a normal phenotype and a higher density. This new strategy based on selective activation of p120/Kaiso but not Wnt/β-catenin signaling obviates the need of using single cells and the risk of EMT, and may be deployed to engineer surgical grafts containing RPE and other tissues. PMID:22590627

  6. Degradation of vinyl chloride (VC) by the sulfite/UV advanced reduction process (ARP): effects of process variables and a kinetic model.

    PubMed

    Liu, Xu; Yoon, Sunhee; Batchelor, Bill; Abdel-Wahab, Ahmed

    2013-06-01

    Vinyl chloride (VC) poses a threat to humans and environment due to its toxicity and carcinogenicity. In this study, an advanced reduction process (ARP) that combines sulfite with UV light was developed to destroy VC. The degradation of VC followed pseudo-first-order decay kinetics and the effects of several experimental factors on the degradation rate constant were investigated. The largest rate constant was observed at pH9, but complete dechlorination was obtained at pH11. Higher sulfite dose and light intensity were found to increase the rate constant linearly. The rate constant had a little drop when the initial VC concentration was below 1.5mg/L and then was approximately constant between 1.5mg/L and 3.1mg/L. A degradation mechanism was proposed to describe reactions between VC and the reactive species that were produced by the photolysis of sulfite. A kinetic model that described major reactions in the system was developed and was able to explain the dependence of the rate constant on the experimental factors examined. This study may provide a new treatment technology for the removal of a variety of halogenated contaminants. PMID:23570912

  7. Lipoamide Acts as an Indirect Antioxidant by Simultaneously Stimulating Mitochondrial Biogenesis and Phase II Antioxidant Enzyme Systems in ARPE-19 Cells

    PubMed Central

    Zhao, Lin; Liu, Zhongbo; Jia, Haiqun; Feng, Zhihui; Liu, Jiankang; Li, Xuesen

    2015-01-01

    In our previous study, we found that pretreatment with lipoamide (LM) more effectively than alpha-lipoic acid (LA) protected retinal pigment epithelial (RPE) cells from the acrolein-induced damage. However, the reasons and mechanisms for the greater effect of LM than LA are unclear. We hypothesize that LM, rather than the more direct antioxidant LA, may act more as an indirect antioxidant. In the present study, we treated ARPE-19 cells with LA and LM and compared their effects on activation of mitochondrial biogenesis and induction of phase II enzyme systems. It is found that LM is more effective than LA on increasing mitochondrial biogenesis and inducing the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its translocation to the nucleus, leading to an increase in expression or activity of phase II antioxidant enzymes (NQO-1, GST, GCL, catalase and Cu/Zn SOD). Further study demonstrated that mitochondrial biogenesis and phase II enzyme induction are closely coupled via energy requirements. These results suggest that LM, compared with the direct antioxidant LA, plays its protective effect on oxidative damage more as an indirect antioxidant to simultaneously stimulate mitochondrial biogenesis and induction of phase II antioxidant enzymes. PMID:26030919

  8. Quantifying electronic correlation strength in a complex oxide: a combined DMFT and ARPES study of LaNiO{sub 3}

    SciTech Connect

    Nowadnick, E. A.; Ruf, J. P.; Park, H.; King, P. D. C.; Schlom, D. G.; Shen, K. M.; Millis, A. J.

    2015-12-07

    The electronic correlation strength is a basic quantity that characterizes the physical properties of materials such as transition metal oxides. Determining correlation strengths requires both precise definitions and a careful comparison between experiment and theory. In this paper, we define the correlation strength via the magnitude of the electron self-energy near the Fermi level. For the case of LaNiO3, we obtain both the experimental and theoretical mass enhancements m/m by considering high resolution angle-resolved photoemission spectroscopy (ARPES) measurements and density functional+dynamical mean field theory (DFT+DMFT) calculations.We use valence-band photoemission data to constrain the free parameters in the theory and demonstrate a quantitative agreement between the experiment and theory when both the realistic crystal structure and strong electronic correlations are taken into account. In addition, by considering DFT+DMFT calculations on epitaxially strained LaNiO3, we find a strain-induced evolution of m/m in qualitative agreement with trends derived from optics experiments. These results provide a benchmark for the accuracy of the DFT+DMFT theoretical approach, and can serve as a test case when considering other complex materials. By establishing the level of accuracy of the theory, this work also will enable better quantitative predictions when engineering new emergent properties in nickelate heterostructures.

  9. Soft X-ray ARPES investigation of the nickelate Fermi surface in exchange biased LaNiO3-LaMnO3 superlattices

    NASA Astrophysics Data System (ADS)

    Bruno, Flavio; McKeown Walker, S.; de la Torre, A.; Tamai, A.; Gibert, M.; Catalano, S.; Triscone, J.-M.; Wang, Z.; Bisti, F.; Strocov, V.; Baumberger, F.

    2015-03-01

    We investigate (111)-oriented superlattices consisting of paramagnetic LaNiO3 (LNO) and ferromagnetic LaMnO3 (LMO). The field dependence of the magnetization in these heterostructures was measured at 5 K after cooling the sample in the presence of a 0.4 T field. Surprisingly, a shift of 15 mT in the magnetization loop towards negative fields along the magnetic field axis was observed. If the same measurement is repeated in a (111) LMO thin film, no exchange bias is observed which implies that LNO is the driving force for the biasing effect exhibited by the heterostructures. Since LNO is a well-known paramagnetic material, the existence of exchange bias in the superlattices implies the existence of an interface-induced magnetic order. Here we use soft x-ray angle resolved photoemission spectroscopy -SX ARPES- to study the electronic band structure of LNO layers in these heterostructures. Due to the increase in photoelectron escape depth in the 500 - 1000 eV energy range, we are able to map the LNO Fermi surface below 7 u.c. of LMO. In this talk we will discuss the similarities and differences in the electronic structure between thin films of (111)-LNO and buried LNO-LMO interfaces.

  10. Streptococcal IgA-binding proteins bind in the Calpha 2-Calpha 3 interdomain region and inhibit binding of IgA to human CD89.

    PubMed

    Pleass, R J; Areschoug, T; Lindahl, G; Woof, J M

    2001-03-16

    Certain pathogenic bacteria express surface proteins that bind to the Fc part of human IgA or IgG. These bacterial proteins are important as immunochemical tools and model systems, but their biological function is still unclear. Here, we describe studies of three streptococcal proteins that bind IgA: the Sir22 and Arp4 proteins of Streptococcus pyogenes and the unrelated beta protein of group B streptococcus. Analysis of IgA domain swap and point mutants indicated that two loops at the Calpha2/Calpha3 domain interface are critical for binding of the streptococcal proteins. This region is also used in binding the human IgA receptor CD89, an important mediator of IgA effector function. In agreement with this finding, the three IgA-binding proteins and a 50-residue IgA-binding peptide derived from Sir22 blocked the ability of IgA to bind CD89. Further, the Arp4 protein inhibited the ability of IgA to trigger a neutrophil respiratory burst via CD89. Thus, we have identified residues on IgA-Fc that play a key role in binding of different streptococcal IgA-binding proteins, and we have identified a mechanism by which a bacterial IgA-binding protein may interfere with IgA effector function. PMID:11096107

  11. Protein phasing at non-atomic resolution by combining Patterson and VLD techniques.

    PubMed

    Caliandro, Rocco; Carrozzini, Benedetta; Cascarano, Giovanni Luca; Comunale, Giuliana; Giacovazzo, Carmelo; Mazzone, Annamaria

    2014-07-01

    Phasing proteins at non-atomic resolution is still a challenge for any ab initio method. A variety of algorithms [Patterson deconvolution, superposition techniques, a cross-correlation function (C map), the VLD (vive la difference) approach, the FF function, a nonlinear iterative peak-clipping algorithm (SNIP) for defining the background of a map and the free lunch extrapolation method] have been combined to overcome the lack of experimental information at non-atomic resolution. The method has been applied to a large number of protein diffraction data sets with resolutions varying from atomic to 2.1 Å, with the condition that S or heavier atoms are present in the protein structure. The applications include the use of ARP/wARP to check the quality of the final electron-density maps in an objective way. The results show that resolution is still the maximum obstacle to protein phasing, but also suggest that the solution of protein structures at 2.1 Å resolution is a feasible, even if still an exceptional, task for the combined set of algorithms implemented in the phasing program. The approach described here is more efficient than the previously described procedures: e.g. the combined use of the algorithms mentioned above is frequently able to provide phases of sufficiently high quality to allow automatic model building. The method is implemented in the current version of SIR2014. PMID:25004976

  12. Systematic mutational analysis of the amino-terminal domain of the Listeria monocytogenes ActA protein reveals novel functions in actin-based motility.

    PubMed

    Lauer, P; Theriot, J A; Skoble, J; Welch, M D; Portnoy, D A

    2001-12-01

    The Listeria monocytogenes ActA protein acts as a scaffold to assemble and activate host cell actin cytoskeletal factors at the bacterial surface, resulting in directional actin polymerization and propulsion of the bacterium through the cytoplasm. We have constructed 20 clustered charged-to-alanine mutations in the NH2-terminal domain of ActA and replaced the endogenous actA gene with these molecular variants. These 20 clones were evaluated in several biological assays for phenotypes associated with particular amino acid changes. Additionally, each protein variant was purified and tested for stimulation of the Arp2/3 complex, and a subset was tested for actin monomer binding. These specific mutations refined the two regions involved in Arp2/3 activation and suggest that the actin-binding sequence of ActA spans 40 amino acids. We also identified a 'motility rate and cloud-to-tail transition' region in which nine contiguous mutations spanning amino acids 165-260 caused motility rate defects and changed the ratio of intracellular bacteria associated with actin clouds and comet tails without affecting Arp2/3 activation. Several unusual motility phenotypes were associated with amino acid changes in this region, including altered paths through the cytoplasm, discontinuous actin tails in host cells and the tendency to 'skid' or dramatically change direction while moving. These unusual phenotypes illustrate the complexity of ActA functions that control the actin-based motility of L. monocytogenes. PMID:11886549

  13. The CARMA Paired Antenna Calibration System: Atmospheric Phase Correction for Millimeter Wave Interferometry and Its Application to Mapping the Ultraluminous Galaxy Arp 193

    NASA Astrophysics Data System (ADS)

    Zauderer, B. Ashley; Bolatto, Alberto D.; Vogel, Stuart N.; Carpenter, John M.; Peréz, Laura M.; Lamb, James W.; Woody, David P.; Bock, Douglas C.-J.; Carlstrom, John E.; Culverhouse, Thomas L.; Curley, Roger; Leitch, Erik M.; Plambeck, Richard L.; Pound, Marc W.; Marrone, Daniel P.; Muchovej, Stephen J.; Mundy, Lee G.; Teng, Stacy H.; Teuben, Peter J.; Volgenau, Nikolaus H.; Wright, Melvyn C. H.; Wu, Dalton

    2016-01-01

    Phase fluctuations introduced by the atmosphere are the main limiting factor in attaining diffraction limited performance in extended interferometric arrays at millimeter and submillimeter wavelengths. We report the results of C-PACS, the Combined Array for Research in Millimeter-Wave Astronomy Paired Antenna Calibration System. We present a systematic study of several hundred test observations taken during the 2009–2010 winter observing season where we utilize CARMA's eight 3.5 m antennas to monitor an atmospheric calibrator while simultaneously acquiring science observations with 6.1 and 10.4 m antennas on baselines ranging from a few hundred meters to ∼2 km. We find that C-PACS is systematically successful at improving coherence on long baselines under a variety of atmospheric conditions. We find that the angular separation between the atmospheric calibrator and target source is the most important consideration, with consistently successful phase correction at CARMA requiring a suitable calibrator located ≲6° away from the science target. We show that cloud cover does not affect the success of C-PACS. We demonstrate C-PACS in typical use by applying it to the observations of the nearby very luminous infrared galaxy Arp 193 in 12CO(2-1) at a linear resolution of ≈70 pc (0.″12 × 0.″18), 3 times better than previously published molecular maps of this galaxy. We resolve the molecular disk rotation kinematics and the molecular gas distribution and measure the gas surface densities and masses on 90 pc scales. We find that molecular gas constitutes ∼30% of the dynamical mass in the inner 700 pc of this object with a surface density ∼104 M⊙ pc‑2 we compare these properties to those of the starburst region of NGC 253.

  14. CALIFA spectroscopy of the interacting galaxy NGC 5394 (Arp 84): starbursts, enhanced [N II]6584 and signs of outflows and shocks

    NASA Astrophysics Data System (ADS)

    Roche, Nathan; Humphrey, Andrew; Gomes, Jean Michel; Papaderos, Polychronis; Lagos, Patricio; Sánchez, Sebastián F.

    2015-11-01

    We investigate the spiral galaxy NGC 5394, which is strongly interacting with the larger spiral NGC 5395 (the pair is Arp 84), using optical integral-field spectroscopy from the CALIFA (Calar Alto Legacy Integral Field Area) survey. Spatially resolved equivalent widths, emission-line ratios and kinematics reveal many features related to the interaction, which has reshaped the galaxy. H α maps (with other diagnostic emission lines) show a concentrated central (r < 1 kpc) starburst and three less luminous star-forming regions (one knot far out in the northern arm), and we estimate the dust-corrected total star-formation rate as 3.39 M⊙ yr- 1. However, much of the galaxy, especially the outer tidal arms, has a post-starburst spectrum, evidence of a more extensive episode of star formation a few ×108 yr ago, triggered by the previous perigalacticon. The [N II]6584/H α ratio is high in the nucleus, reaching 0.63 at the centre, which we interpret as related to high electron density (ne ≃ 750 cm- 3 from the [S II]{6717over 6731} ratio). We find a central region of strong and blueshifted Na I(5890,5896) absorption, indicative of a starburst-driven outflow from the nucleus at an estimated velocity ˜223 km s- 1. The CALIFA data also show an annular region at radii 2.25-4 kpc from the nucleus, with elevated ratios of [N II], [O I]6300 etc. to the Balmer lines - this is evidence of shock excitation, which might be the result of interaction-triggered gas inflow.

  15. The CARMA Paired Antenna Calibration System: Atmospheric Phase Correction for Millimeter Wave Interferometry and Its Application to Mapping the Ultraluminous Galaxy Arp 193

    NASA Astrophysics Data System (ADS)

    Zauderer, B. Ashley; Bolatto, Alberto D.; Vogel, Stuart N.; Carpenter, John M.; Peréz, Laura M.; Lamb, James W.; Woody, David P.; Bock, Douglas C.-J.; Carlstrom, John E.; Culverhouse, Thomas L.; Curley, Roger; Leitch, Erik M.; Plambeck, Richard L.; Pound, Marc W.; Marrone, Daniel P.; Muchovej, Stephen J.; Mundy, Lee G.; Teng, Stacy H.; Teuben, Peter J.; Volgenau, Nikolaus H.; Wright, Melvyn C. H.; Wu, Dalton

    2016-01-01

    Phase fluctuations introduced by the atmosphere are the main limiting factor in attaining diffraction limited performance in extended interferometric arrays at millimeter and submillimeter wavelengths. We report the results of C-PACS, the Combined Array for Research in Millimeter-Wave Astronomy Paired Antenna Calibration System. We present a systematic study of several hundred test observations taken during the 2009-2010 winter observing season where we utilize CARMA's eight 3.5 m antennas to monitor an atmospheric calibrator while simultaneously acquiring science observations with 6.1 and 10.4 m antennas on baselines ranging from a few hundred meters to ˜2 km. We find that C-PACS is systematically successful at improving coherence on long baselines under a variety of atmospheric conditions. We find that the angular separation between the atmospheric calibrator and target source is the most important consideration, with consistently successful phase correction at CARMA requiring a suitable calibrator located ≲6° away from the science target. We show that cloud cover does not affect the success of C-PACS. We demonstrate C-PACS in typical use by applying it to the observations of the nearby very luminous infrared galaxy Arp 193 in 12CO(2-1) at a linear resolution of ≈70 pc (0.″12 × 0.″18), 3 times better than previously published molecular maps of this galaxy. We resolve the molecular disk rotation kinematics and the molecular gas distribution and measure the gas surface densities and masses on 90 pc scales. We find that molecular gas constitutes ˜30% of the dynamical mass in the inner 700 pc of this object with a surface density ˜104 M⊙ pc-2 we compare these properties to those of the starburst region of NGC 253.

  16. Theoretical Modelling of the Diffuse Emission of (gamma)-rays From Extreme Regions of Star Formation: The Case of Arp 220

    SciTech Connect

    Torres, D F

    2004-07-09

    Our current understanding of ultraluminous infrared galaxies suggest that they are recent galaxy mergers in which much of the gas in the former spiral disks, particularly that located at distances less than 5 kpc from each of the pre-merger nuclei, has fallen into a common center, triggering a huge starburst phenomenon. This large nuclear concentration of molecular gas has been detected by many groups, and estimates of molecular mass and density have been made. Not surprisingly, these estimates were found to be orders of magnitude larger than the corresponding values found in our Galaxy. In this paper, a self-consistent model of the high energy emission of the super-starburst galaxy Arp 220 is presented. The model also provides an estimate of the radio emission from each of the components of the central region of the galaxy (western and eastern extreme starbursts, and molecular disk). The predicted radio spectrum is found as a result of the synchrotron and free-free emission, and absorption, of the primary and secondary steady population of electrons and positrons. The latter is output of charged pion decay and knock-on leptonic production, subject to a full set of losses in the interstellar medium. The resulting radio spectrum is in agreement with sub-arcsec radio observations, what allows to estimate the magnetic field. In addition, the FIR emission is modeled with dust emissivity, and the computed FIR photon density is used as a target for inverse Compton process as well as to give account of losses in the {gamma}-ray scape. Bremsstrahlung emission and neutral pion decay are also computed, and the {gamma}-ray spectrum is finally predicted. Future possible observations with GLAST, and the ground based Cherenkov telescopes are discussed.

  17. Exploration of the dynamic properties of protein complexes predicted from spatially constrained protein-protein interaction networks.

    PubMed

    Yen, Eric A; Tsay, Aaron; Waldispuhl, Jerome; Vogel, Jackie

    2014-05-01

    Protein complexes are not static, but rather highly dynamic with subunits that undergo 1-dimensional diffusion with respect to each other. Interactions within protein complexes are modulated through regulatory inputs that alter interactions and introduce new components and deplete existing components through exchange. While it is clear that the structure and function of any given protein complex is coupled to its dynamical properties, it remains a challenge to predict the possible conformations that complexes can adopt. Protein-fragment Complementation Assays detect physical interactions between protein pairs constrained to ≤8 nm from each other in living cells. This method has been used to build networks composed of 1000s of pair-wise interactions. Significantly, these networks contain a wealth of dynamic information, as the assay is fully reversible and the proteins are expressed in their natural context. In this study, we describe a method that extracts this valuable information in the form of predicted conformations, allowing the user to explore the conformational landscape, to search for structures that correlate with an activity state, and estimate the abundance of conformations in the living cell. The generator is based on a Markov Chain Monte Carlo simulation that uses the interaction dataset as input and is constrained by the physical resolution of the assay. We applied this method to an 18-member protein complex composed of the seven core proteins of the budding yeast Arp2/3 complex and 11 associated regulators and effector proteins. We generated 20,480 output structures and identified conformational states using principle component analysis. We interrogated the conformation landscape and found evidence of symmetry breaking, a mixture of likely active and inactive conformational states and dynamic exchange of the core protein Arc15 between core and regulatory components. Our method provides a novel tool for prediction and visualization of the hidden

  18. Co-Expression of Anti-Rotavirus Proteins (Llama VHH Antibody Fragments) in Lactobacillus: Development and Functionality of Vectors Containing Two Expression Cassettes in Tandem

    PubMed Central

    Günaydın, Gökçe; Álvarez, Beatriz; Lin, Yin; Hammarström, Lennart; Marcotte, Harold

    2014-01-01

    Rotavirus is an important pediatric pathogen, causing severe diarrhea and being associated with a high mortality rate causing approximately 500 000 deaths annually worldwide. Even though some vaccines are currently available, their efficacy is lower in the developing world, as compared to developed countries. Therefore, alternative or complementary treatment options are needed in the developing countries where the disease burden is the largest. The effect of Lactobacillus in promoting health and its use as a vehicle for delivery of protein and antibody fragments was previously shown. In this study, we have developed co-expression vectors enabling Lactobacillus paracasei BL23 to produce two VHH fragments against rotavirus (referred to as anti-rotavirus proteins 1 and 3, ARP1 and ARP3) as secreted and/or surface displayed products. ARP1 and ARP3 fragments were successfully co-expressed as shown by Western blot and flow cytometry. In addition, engineered Lactobacillus produced VHH antibody fragments were shown to bind to a broad range of rotavirus serotypes (including the human rotavirus strains 69M, Va70, F45, DS1, Wa and ST3 and simian rotavirus strains including RRV and SA11), by flow cytometry and ELISA. Hereby, we have demonstrated for the first time that when RRV was captured by one VHH displayed on the surface of co-expressor Lactobacillus, targeting other epitope was possible with another VHH secreted from the same bacterium. Therefore, Lactobacillus producing two VHH antibody fragments may potentially serve as treatment against rotavirus with a reduced risk of development of escape mutants. This co-expression and delivery platform can also be used for delivery of VHH fragments against a variety of mucosal pathogens or production of other therapeutic molecules. PMID:24781086

  19. Actin-interacting and flagellar proteins in Leishmania spp.: Bioinformatics predictions to functional assignments in phagosome formation

    PubMed Central

    2009-01-01

    Several motile processes are responsible for the movement of proteins into and within the flagellar membrane, but little is known about the process by which specific proteins (either actin-associated or not) are targeted to protozoan flagellar membranes. Actin is a major cytoskeleton protein, while polymerization and depolymerization of parasite actin and actin-interacting proteins (AIPs) during both processes of motility and host cell entry might be key events for successful infection. For a better understanding the eukaryotic flagellar dynamics, we have surveyed genomes, transcriptomes and proteomes of pathogenic Leishmania spp. to identify pertinent genes/proteins and to build in silico models to properly address their putative roles in trypanosomatid virulence. In a search for AIPs involved in flagellar activities, we applied computational biology and proteomic tools to infer from the biological meaning of coronins and Arp2/3, two important elements in phagosome formation after parasite phagocytosis by macrophages. Results presented here provide the first report of Leishmania coronin and Arp2/3 as flagellar proteins that also might be involved in phagosome formation through actin polymerization within the flagellar environment. This is an issue worthy of further in vitro examination that remains now as a direct, positive bioinformatics-derived inference to be presented. PMID:21637533

  20. Actin-interacting and flagellar proteins in Leishmania spp.: Bioinformatics predictions to functional assignments in phagosome formation.

    PubMed

    Diniz, Michely C; Costa, Marcília P; Pacheco, Ana C L; Kamimura, Michel T; Silva, Samara C; Carneiro, Laura D G; Sousa, Ana P L; Soares, Carlos E A; Souza, Celeste S F; de Oliveira, Diana Magalhães

    2009-07-01

    Several motile processes are responsible for the movement of proteins into and within the flagellar membrane, but little is known about the process by which specific proteins (either actin-associated or not) are targeted to protozoan flagellar membranes. Actin is a major cytoskeleton protein, while polymerization and depolymerization of parasite actin and actin-interacting proteins (AIPs) during both processes of motility and host cell entry might be key events for successful infection. For a better understanding the eukaryotic flagellar dynamics, we have surveyed genomes, transcriptomes and proteomes of pathogenic Leishmania spp. to identify pertinent genes/proteins and to build in silico models to properly address their putative roles in trypanosomatid virulence. In a search for AIPs involved in flagellar activities, we applied computational biology and proteomic tools to infer from the biological meaning of coronins and Arp2/3, two important elements in phagosome formation after parasite phagocytosis by macrophages. Results presented here provide the first report of Leishmania coronin and Arp2/3 as flagellar proteins that also might be involved in phagosome formation through actin polymerization within the flagellar environment. This is an issue worthy of further in vitro examination that remains now as a direct, positive bioinformatics-derived inference to be presented. PMID:21637533

  1. High energy resolution ARPES measurements of the normal and superconducting states of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}}

    SciTech Connect

    Dessau, D.S.; King, D.M.; Shen, Z.X.

    1993-08-01

    The near-E{sub F} electronic structure and Fermi surface of Bi2212 has been mapped out with ARPES. A key feature of our measured bandstructure is the existence of an extended region of flat CuO{sub 2}-derived bands at E{sub F}. Comparative analysis of this data with that from NdCeCuO and YBCO{sub 7} suggests that many of the anomalous (normal) physical properties of Bi2212 and YBCO{sub 7} (NdCeCuO) may be related to the existence (absence) of such bands at E{sub F}. Superconducting gap anisotropy at least an order of magnitude larger than that of the conventional superconductors has been observed in the a-b plane of Bi2212 in ARPES. For samples with {Tc} of 88K, the gap size reaches a maximum of approximately 20 MeV along the Cu-O bond direction, and a minimum of much smaller or vanishing magnitude 450 away. The experimental data is discussed within the context of various theoretical models. In particular, a detailed comparison with what is expected from a superconductor with a d{sub x2-y2} order parameter is carried out, yielding a consistent picture.

  2. Identification of Host Proteins Involved in Rickettsial Invasion of Tick Cells

    PubMed Central

    Sunyakumthorn, Piyanate; Banajee, Kaikhushroo H.; Verhoeve, Victoria I.; Kearney, Michael T.; Macaluso, Kevin R.

    2014-01-01

    Tick-borne spotted fever group (SFG) Rickettsia species are obligate intracellular bacteria capable of infecting both vertebrate and invertebrate host cells, an essential process for subsequent bacterial survival in distinct hosts. The host cell signaling molecules involved in the uptake of Rickettsia into mammalian and Drosophila cells have been identified; however, invasion into tick cells is understudied. Considering the movement of SFG Rickettsia between vertebrate and invertebrate hosts, the hypothesis is that conserved mechanisms are utilized for host cell invasion. The current study employed biochemical inhibition assays to determine the tick proteins involved in Rickettsia montanensis infection of tick-derived cells from a natural host, Dermacentor variabilis. The results revealed several tick proteins important for rickettsial invasion, including actin filaments, actin-related protein 2/3 complex, phosphatidylinositol-3′-kinase, protein tyrosine kinases (PTKs), Src family PTK, focal adhesion kinase, Rho GTPase Rac1, and neural Wiskott-Aldrich syndrome protein. Delineating the molecular mechanisms of rickettsial infection is critical to a thorough understanding of rickettsial transmission in tick populations and the ecology of tick-borne rickettsial diseases. PMID:25547795

  3. Identification of host proteins involved in rickettsial invasion of tick cells.

    PubMed

    Petchampai, Natthida; Sunyakumthorn, Piyanate; Banajee, Kaikhushroo H; Verhoeve, Victoria I; Kearney, Michael T; Macaluso, Kevin R

    2015-03-01

    Tick-borne spotted fever group (SFG) Rickettsia species are obligate intracellular bacteria capable of infecting both vertebrate and invertebrate host cells, an essential process for subsequent bacterial survival in distinct hosts. The host cell signaling molecules involved in the uptake of Rickettsia into mammalian and Drosophila cells have been identified; however, invasion into tick cells is understudied. Considering the movement of SFG Rickettsia between vertebrate and invertebrate hosts, the hypothesis is that conserved mechanisms are utilized for host cell invasion. The current study employed biochemical inhibition assays to determine the tick proteins involved in Rickettsia montanensis infection of tick-derived cells from a natural host, Dermacentor variabilis. The results revealed several tick proteins important for rickettsial invasion, including actin filaments, actin-related protein 2/3 complex, phosphatidylinositol-3'-kinase, protein tyrosine kinases (PTKs), Src family PTK, focal adhesion kinase, Rho GTPase Rac1, and neural Wiskott-Aldrich syndrome protein. Delineating the molecular mechanisms of rickettsial infection is critical to a thorough understanding of rickettsial transmission in tick populations and the ecology of tick-borne rickettsial diseases. PMID:25547795

  4. The Molecular Basis of Leukocyte Adhesion Involving Phosphatidic Acid and Phospholipase D*

    PubMed Central

    Speranza, Francis; Mahankali, Madhu; Henkels, Karen M.; Gomez-Cambronero, Julian

    2014-01-01

    Defining how leukocytes adhere to solid surfaces, such as capillary beds, and the subsequent migration through the extracellular matrix, is a central biological issue. We show here that phospholipase D (PLD) and its enzymatic reaction product, phosphatidic acid (PA), regulate cell adhesion of immune cells (macrophages and neutrophils) to collagen and have defined the underlying molecular mechanism in a spatio-temporal manner that coincides with PLD activity timing. A rapid (t½ = 4 min) and transient activation of the PLD1 isoform occurs upon adhesion, and a slower (t½ = 7.5 min) but prolonged (>30 min) activation occurs for PLD2. Importantly, PA directly binds to actin-related protein 3 (Arp3) at EC50 = 22 nm, whereas control phosphatidylcholine did not bind. PA-activated Arp3 hastens actin nucleation with a kinetics of t½ = 3 min at 300 nm (compared with controls of no PA, t½ = 5 min). Thus, PLD and PA are intrinsic components of cell adhesion, which reinforce each other in a positive feedback loop and react from cues from their respective solid substrates. In nascent adhesion, PLD1 is key, whereas a sustained adhesion in mature or established focal points is dependent upon PLD2, PA, and Arp3. A prolonged adhesion could effectively counteract the reversible intrinsic nature of this cellular process and constitute a key player in chronic inflammation. PMID:25187519

  5. Molecular Characterization of Neurally Expressing Genes in the Para Sodium Channel Gene Cluster of Drosophila

    PubMed Central

    Hong, C. S.; Ganetzky, B.

    1996-01-01

    To elucidate the mechanisms regulating expression of para, which encodes the major class of sodium channels in the Drosophila nervous system, we have tried to locate upstream cis-acting regulatory elements by mapping the transcriptional start site and analyzing the region immediately upstream of para in region 14D of the polytene chromosomes. From these studies, we have discovered that the region contains a cluster of neurally expressing genes. Here we report the molecular characterization of the genomic organization of the 14D region and the genes within this region, which are: calnexin (Cnx), actin related protein 14D (Arp14D), calcineurin A 14D (CnnA14D), and chromosome associated protein (Cap). The tight clustering of these genes, their neuronal expression patterns, and their potential functions related to expression, modulation, or regulation of sodium channels raise the possibility that these genes represent a functionally related group sharing some coordinate regulatory mechanism. PMID:8849894

  6. Phosphoproteome Profiling of SH-SY5y Neuroblastoma Cells Treated with Anesthetics: Sevoflurane and Isoflurane Affect the Phosphorylation of Proteins Involved in Cytoskeletal Regulation.

    PubMed

    Lee, Joomin; Ahn, Eunsook; Park, Wyun Kon; Park, Seyeon

    2016-01-01

    Inhalation anesthetics are used to decrease the spinal cord transmission of painful stimuli. However, the molecular or biochemical processes within cells that regulate anesthetic-induced responses at the cellular level are largely unknown. Here, we report the phosphoproteome profile of SH-SY5y human neuroblastoma cells treated with sevoflurane, a clinically used anesthetic. Phosphoproteins were isolated from cell lysates and analyzed using two-dimensional gel electrophoresis. The phosphorylation of putative anesthetic-responsive marker proteins was validated using western blot analysis in cells treated with both sevoflurane and isoflurane. A total of 25 phosphoproteins were identified as differentially phosphorylated proteins. These included key regulators that signal cytoskeletal remodeling steps in pathways related to vesicle trafficking, axonal growth, and cell migration. These proteins included the Rho GTPase, Ras-GAP SH3 binding protein, Rho GTPase activating protein, actin-related protein, and actin. Sevoflurane and isoflurane also resulted in the dissolution of F-actin fibers in SH-SY5y cells. Our results show that anesthetics affect the phosphorylation of proteins involved in cytoskeletal remodeling pathways. PMID:27611435

  7. The Disruption of the Cytoskeleton during Semaphorin 3A induced Growth Cone Collapse Correlates with Differences in Actin Organization and Associated Binding Proteins

    PubMed Central

    Brown, Jacquelyn A; Bridgman, Paul C

    2010-01-01

    Repulsive guidance cues induce growth cone collapse or collapse and retraction. Collapse results from disruption and loss of the actin cytoskeleton. Actin rich regions of growth cones contain binding proteins that influence filament organization, such as Arp2/3, cortactin, and fascin, but little is known about the role that these proteins play in collapse. Here we show that Semaphorin 3A (Sema 3A), which is repulsive to mouse dorsal root ganglion neurons, has unequal effects on actin binding proteins and their associated filaments. The immunofluorescence staining intensity of Arp-2 and cortactin decreases relative to total protein, while in unextracted growth cones fascin increases. Fascin and myosin IIB staining redistribute and show increased overlap. The degree of actin filament loss during collapse correlates with filament superstructures detected by rotary shadow electron microscopy. Collapse results in the loss of branched f-actin meshworks, while actin bundles are partially retained to varying degrees. Taken together with the known affects of Sema 3A on actin, this suggests a model for collapse that follows a sequence; depolymerization of actin meshworks followed by partial depolymerization of fascin associated actin bundles and their movement to the neurite to complete collapse. The relocated fascin associated actin bundles may provide the substrate for actomyosin contractions that produce retraction. PMID:19513995

  8. The Recent De Novo Origin of Protein C-Termini

    PubMed Central

    Andreatta, Matthew E.; Levine, Joshua A.; Foy, Scott G.; Guzman, Lynette D.; Kosinski, Luke J.; Cordes, Matthew H.J.; Masel, Joanna

    2015-01-01

    Protein-coding sequences can arise either from duplication and divergence of existing sequences, or de novo from noncoding DNA. Unfortunately, recently evolved de novo genes can be hard to distinguish from false positives, making their study difficult. Here, we study a more tractable version of the process of conversion of noncoding sequence into coding: the co-option of short segments of noncoding sequence into the C-termini of existing proteins via the loss of a stop codon. Because we study recent additions to potentially old genes, we are able to apply a variety of stringent quality filters to our annotations of what is a true protein-coding gene, discarding the putative proteins of unknown function that are typical of recent fully de novo genes. We identify 54 examples of C-terminal extensions in Saccharomyces and 28 in Drosophila, all of them recent enough to still be polymorphic. We find one putative gene fusion that turns out, on close inspection, to be the product of replicated assembly errors, further highlighting the issue of false positives in the study of rare events. Four of the Saccharomyces C-terminal extensions (to ADH1, ARP8, TPM2, and PIS1) that survived our quality filters are predicted to lead to significant modification of a protein domain structure. PMID:26002864

  9. Actin turnover-dependent fast dissociation of capping protein in the dendritic nucleation actin network: evidence of frequent filament severing.

    PubMed

    Miyoshi, Takushi; Tsuji, Takahiro; Higashida, Chiharu; Hertzog, Maud; Fujita, Akiko; Narumiya, Shuh; Scita, Giorgio; Watanabe, Naoki

    2006-12-18

    Actin forms the dendritic nucleation network and undergoes rapid polymerization-depolymerization cycles in lamellipodia. To elucidate the mechanism of actin disassembly, we characterized molecular kinetics of the major filament end-binding proteins Arp2/3 complex and capping protein (CP) using single-molecule speckle microscopy. We have determined the dissociation rates of Arp2/3 and CP as 0.048 and 0.58 s(-1), respectively, in lamellipodia of live XTC fibroblasts. This CP dissociation rate is three orders of magnitude faster than in vitro. CP dissociates slower from actin stress fibers than from the lamellipodial actin network, suggesting that CP dissociation correlates with actin filament dynamics. We found that jasplakinolide, an actin depolymerization inhibitor, rapidly blocked the fast CP dissociation in cells. Consistently, the coexpression of LIM kinase prolonged CP speckle lifetime in lamellipodia. These results suggest that cofilin-mediated actin disassembly triggers CP dissociation from actin filaments. We predict that filament severing and end-to-end annealing might take place fairly frequently in the dendritic nucleation actin arrays. PMID:17178911

  10. Retinal proteins modified by 4-hydroxynonenal: identification of molecular targets.

    PubMed

    Kapphahn, Rebecca J; Giwa, Babatomiwa M; Berg, Kristin M; Roehrich, Heidi; Feng, Xiao; Olsen, Timothy W; Ferrington, Deborah A

    2006-07-01

    The reactive aldehyde, 4-hydroxynonenal (HNE), is a product of lipid peroxidation that can covalently modify and inactivate proteins. Previously, we reported increased HNE modification of select retinal proteins resolved by one-dimensional gel electrophoresis in aged Fisher 344 x Brown Norway rats (Louie, J.L., Kapphahn, R.J., Ferrington, D.A., 2002. Proteasome function and protein oxidation in the aged retina. Exp. Eye Res. 75, 271-284). In the current study, quantitative assessment of HNE molar content using slot blot immunoassays showed HNE content is increased 30% in aged rat retina. In contrast, there was no age-related difference in HNE content in individual spots resolved by 2D gel electrophoresis suggesting the increased modification is likely on membrane proteins that are missing on 2D gels. The HNE-immunoreactive proteins resolved by 2D gel electrophoresis were identified by MALDI-TOF mass spectrometry. These proteins are involved in metabolism, chaperone function, and fatty acid transport. Proteins that were frequently modified and had the highest molar content of HNE included triosephosphate isomerase, alpha enolase, heat shock cognate 70 and betaB2 crystallin. Immunochemical detection of HNE adducts on retinal sections showed greater immune reaction in ganglion cells, photoreceptor inner segment, and the inner plexiform layer. Identification of HNE modified proteins in two alternative model systems, human retinal pigment epithelial cells in culture (ARPE19) and human donor eyes, indicated that triosephosphate isomerase and alpha enolase are generally modified. These results identify a common subset of proteins that contain HNE adducts and suggest that select retinal proteins are molecular targets for HNE modification. PMID:16530755

  11. A Pan1/End3/Sla1 complex links Arp2/3-mediated actin assembly to sites of clathrin-mediated endocytosis

    PubMed Central

    Sun, Yidi; Leong, Nicole T.; Wong, Tiffany; Drubin, David G.

    2015-01-01

    More than 60 highly conserved proteins appear sequentially at sites of clathrin-mediated endocytosis in yeast and mammals. The yeast Eps15-related proteins Pan1 and End3 and the CIN85-related protein Sla1 are known to interact with each other in vitro, and they all appear after endocytic-site initiation but before endocytic actin assembly, which facilitates membrane invagination/scission. Here we used live-cell imaging in parallel with genetics and biochemistry to explore comprehensively the dynamic interactions and functions of Pan1, End3, and Sla1. Our results indicate that Pan1 and End3 associate in a stable manner and appear at endocytic sites before Sla1. The End3 C-terminus is necessary and sufficient for its cortical localization via interaction with Pan1, whereas the End3 N-terminus plays a crucial role in Sla1 recruitment. We systematically examined the dynamic behaviors of endocytic proteins in cells in which Pan1 and End3 were simultaneously eliminated, using the auxin-inducible degron system. The results lead us to propose that endocytic-site initiation and actin assembly are separable processes linked by a Pan1/End3/Sla1 complex. Finally, our study provides mechanistic insights into how Pan1 and End3 function with Sla1 to coordinate cargo capture with actin assembly. PMID:26337384

  12. Curcumin analog 1, 5-bis (2-trifluoromethylphenyl)-1, 4-pentadien-3-one exhibits enhanced ability on Nrf2 activation and protection against acrolein-induced ARPE-19 cell toxicity

    SciTech Connect

    Li, Yuan; Zou, Xuan; Cao, Ke; Xu, Jie; Yue, Tingting; Dai, Fang; Zhou, Bo; Lu, Wuyuan; Feng, Zhihui; Liu, Jiankang

    2013-11-01

    Curcumin, a phytochemical agent in the spice turmeric, has received increasing attention for its anticancer, anti-inflammatory and antioxidant properties. However, application of curcumin has been limited due to its insolubility in water and poor bioavailability both clinically and experimentally. In addition, the protective effects and mechanisms of curcumin in eye diseases have been poorly studied. In the present study, we synthesized a curcumin analog, 1, 5-bis (2-trifluoromethylphenyl)-1, 4-pentadien-3-one (C3), which displayed improved protective effect against acrolein-induced toxicity in a human retinal pigment epithelial cell line (ARPE-19). At 5 μM, curcumin completely protected against acrolein-induced cell oxidative damage and preserved GSH levels and mitochondrial function. Surprisingly, C3 displayed a complete protective effect at 0.5 μM, which was much more efficient than curcumin. Both 0.5 μM C3 and 5 μM curcumin induced Nrf2 nuclear translocation and Nrf2 target genes transcription similarly. Experiments using Nrf2 siRNA showed that the protective effects of curcumin and C3 were eliminated by Nrf2 knockdown. Additionally, both curcumin and C3 activated the PI3/Akt pathway, however, Nrf2 activation was independent of this pathway, and therefore, we hypothesized that both curcumin and C3 activated phase II enzymes via directly disrupting the Nrf2/Keap1 complex and promoting Nrf2's nuclear translocation. Since acrolein challenge of ARPE-19 cells has been used as a model of smoking and age-related macular degeneration (AMD), we concluded that the curcumin analog, C3, may be a more promising drug candidate for its potential application for the prevention and treatment of eye diseases, such as AMD. - Highlights: • We examine toxicity effects of cigarette smoking component acrolein in retina cells. • We report a more efficient curcumin analog (C3) protecting cellular function. • Mitochondrial function and phase II enzyme activation are the major

  13. Helicobacter pylori CagA Induces AGS Cell Elongation through a Cell Retraction Defect That Is Independent of Cdc42, Rac1, and Arp2/3▿ †

    PubMed Central

    Bourzac, Kevin M.; Botham, Crystal M.; Guillemin, Karen

    2007-01-01

    Helicobacter pylori, which infects over one-half the world's population, is a significant risk factor in a spectrum of gastric diseases, including peptic ulcers and gastric cancer. Strains of H. pylori that deliver the effector molecule CagA into host cells via a type IV secretion system are associated with more severe disease outcomes. In a tissue culture model of infection, CagA delivery results in a dramatic cellular elongation referred to as the “hummingbird” phenotype, which is characterized by long, thin cellular extensions. These actin-based cytoskeletal rearrangements are reminiscent of structures that are regulated by Rho GTPases and the Arp2/3 complex. We tested whether these signaling pathways were important in the H. pylori-induced cell elongation phenotype. Contrary to our expectations, we found that these molecules are dispensable for cell elongation. Instead, time-lapse video microscopy revealed that cells infected by cagA+ H. pylori become elongated because they fail to release their back ends during cell locomotion. Consistent with a model in which CagA causes cell elongation by inhibiting the disassembly of adhesive cell contacts at migrating cells' lagging ends, immunohistochemical analysis revealed that focal adhesion complexes persist at the distal tips of elongated cell projections. Thus, our data implicate a set of signaling molecules in the hummingbird phenotype that are different than the molecules previously suspected. PMID:17194805

  14. Site-specific protein adducts of 4-hydroxy-2(E)-nonenal in human THP-1 monocytic cells: Protein carbonylation is diminished by ascorbic acid

    PubMed Central

    Chavez, Juan; Chung, Woon-Gye; Miranda, Cristobal L.; Singhal, Mudita; Stevens, Jan F.; Maier, Claudia S.

    2010-01-01

    The protein targets and sites of modification by 4-hydroxy-2(E)-nonenal (HNE) in human monocytic THP-1 cells after exogenous exposure to HNE were examined using a multi-pronged proteomic approach involving electrophoretic, immunoblotting and mass spectrometric methods. Immunoblot analysis using monoclonal anti-HNE antibodies showed several proteins as targets of HNE adduction. Pretreatment of THP-1 cells with ascorbic acid resulted in reduced levels of HNE-protein adducts. Biotinylation of Michael-type HNE adducts using an aldehyde-reactive hydroxylamine-functionalized probe (aldehyde-reactive probe, ARP) and subsequent enrichment facilitated the identification and site-specific assignment of the modifications by LC-MS/MS analysis. Sixteen proteins were unequivocally identified as targets of HNE adduction and eighteen sites of HNE modification at Cys and His residues were assigned. HNE exposure of THP-1 cells resulted in the modification of proteins involved in cytoskeleton organization and regulation, proteins associated with stress responses and enzymes of the glycolytic and other metabolic pathways. This study yielded the first evidence of site-specific adduction of HNE to Cys-295 in tubulin α-1B chain, Cys-351 and Cys-499 in α-actinin-4, Cys-328 in vimentin, Cys-369 in D-3-phosphoglycerate dehydrogenase and His-246 in aldolase A. PMID:20043646

  15. The Varicella-Zoster Virus Portal Protein Is Essential for Cleavage and Packaging of Viral DNA

    PubMed Central

    Visalli, Melissa A.; House, Brittany L.; Selariu, Anca; Zhu, Hua

    2014-01-01

    ABSTRACT The varicella-zoster virus (VZV) open reading frame 54 (ORF54) gene encodes an 87-kDa monomer that oligomerizes to form the VZV portal protein, pORF54. pORF54 was hypothesized to perform a function similar to that of a previously described herpes simplex virus 1 (HSV-1) homolog, pUL6. pUL6 and the associated viral terminase are required for processing of concatemeric viral DNA and packaging of individual viral genomes into preformed capsids. In this report, we describe two VZV bacterial artificial chromosome (BAC) constructs with ORF54 gene deletions, Δ54L (full ORF deletion) and Δ54S (partial internal deletion). The full deletion of ORF54 likely disrupted essential adjacent genes (ORF53 and ORF55) and therefore could not be complemented on an ORF54-expressing cell line (ARPE54). In contrast, Δ54S was successfully propagated in ARPE54 cells but failed to replicate in parental, noncomplementing ARPE19 cells. Transmission electron microscopy confirmed the presence of only empty VZV capsids in Δ54S-infected ARPE19 cell nuclei. Similar to the HSV-1 genome, the VZV genome is composed of a unique long region (UL) and a unique short region (US) flanked by inverted repeats. DNA from cells infected with parental VZV (VZVLUC strain) contained the predicted UL and US termini, whereas cells infected with Δ54S contained neither. This result demonstrates that Δ54S is not able to process and package viral DNA, thus making pORF54 an excellent chemotherapeutic target. In addition, the utility of BAC constructs Δ54L and Δ54S as tools for the isolation of site-directed ORF54 mutants was demonstrated by recombineering single-nucleotide changes within ORF54 that conferred resistance to VZV-specific portal protein inhibitors. IMPORTANCE Antivirals with novel mechanisms of action would provide additional therapeutic options to treat human herpesvirus infections. Proteins involved in the herpesviral DNA encapsidation process have become promising antiviral targets

  16. Phase transitions in the assembly of multivalent signalling proteins

    SciTech Connect

    Li, Pilong; Banjade, Sudeep; Cheng, Hui-Chun; Kim, Soyeon; Chen, Baoyu; Guo, Liang; Llaguno, Marc; Hollingsworth, Javoris V.; King, David S.; Banani, Salman F.; Russo, Paul S.; Jiang, Qiu-Xing; Nixon, B. Tracy; Rosen, Michael K.

    2013-04-08

    Cells are organized on length scales ranging from angstrom to micrometers. However, the mechanisms by which angstrom-scale molecular properties are translated to micrometer-scale macroscopic properties are not well understood. Here we show that interactions between diverse synthetic, multivalent macromolecules (including multi-domain proteins and RNA) produce sharp liquid-liquid-demixing phase separations, generating micrometer-sized liquid droplets in aqueous solution. This macroscopic transition corresponds to a molecular transition between small complexes and large, dynamic supramolecular polymers. The concentrations needed for phase transition are directly related to the valency of the interacting species. In the case of the actin-regulatory protein called neural Wiskott-Aldrich syndrome protein (N-WASP) interacting with its established biological partners NCK and phosphorylated nephrin1, the phase transition corresponds to a sharp increase in activity towards an actin nucleation factor, the Arp2/3 complex. The transition is governed by the degree of phosphorylation of nephrin, explaining how this property of the system can be controlled to regulatory effect by kinases. The widespread occurrence of multivalent systems suggests that phase transitions may be used to spatially organize and biochemically regulate information throughout biology.

  17. Phase transitions in the assembly of multivalent signalling proteins.

    PubMed

    Li, Pilong; Banjade, Sudeep; Cheng, Hui-Chun; Kim, Soyeon; Chen, Baoyu; Guo, Liang; Llaguno, Marc; Hollingsworth, Javoris V; King, David S; Banani, Salman F; Russo, Paul S; Jiang, Qiu-Xing; Nixon, B Tracy; Rosen, Michael K

    2012-03-15

    Cells are organized on length scales ranging from ångström to micrometres. However, the mechanisms by which ångström-scale molecular properties are translated to micrometre-scale macroscopic properties are not well understood. Here we show that interactions between diverse synthetic, multivalent macromolecules (including multi-domain proteins and RNA) produce sharp liquid-liquid-demixing phase separations, generating micrometre-sized liquid droplets in aqueous solution. This macroscopic transition corresponds to a molecular transition between small complexes and large, dynamic supramolecular polymers. The concentrations needed for phase transition are directly related to the valency of the interacting species. In the case of the actin-regulatory protein called neural Wiskott-Aldrich syndrome protein (N-WASP) interacting with its established biological partners NCK and phosphorylated nephrin, the phase transition corresponds to a sharp increase in activity towards an actin nucleation factor, the Arp2/3 complex. The transition is governed by the degree of phosphorylation of nephrin, explaining how this property of the system can be controlled to regulatory effect by kinases. The widespread occurrence of multivalent systems suggests that phase transitions may be used to spatially organize and biochemically regulate information throughout biology. PMID:22398450

  18. Protein Condensation

    NASA Astrophysics Data System (ADS)

    Gunton, James D.; Shiryayev, Andrey; Pagan, Daniel L.

    2007-09-01

    Preface; 1. Introduction; 2. Globular protein structure; 3. Experimental methods; 4. Thermodynamics and statistical mechanics; 5. Protein-protein interactions; 6. Theoretical studies of equilibrium; 7. Nucleation theory; 8. Experimental studies of nucleation; 9. Lysozyme; 10. Some other globular proteins; 11. Membrane proteins; 12. Crystallins and cataracts; 13. Sickle hemoglobin and sickle cell anemia; 14, Alzheimer's disease; Index.

  19. Protein Condensation

    NASA Astrophysics Data System (ADS)

    Gunton, James D.; Shiryayev, Andrey; Pagan, Daniel L.

    2014-07-01

    Preface; 1. Introduction; 2. Globular protein structure; 3. Experimental methods; 4. Thermodynamics and statistical mechanics; 5. Protein-protein interactions; 6. Theoretical studies of equilibrium; 7. Nucleation theory; 8. Experimental studies of nucleation; 9. Lysozyme; 10. Some other globular proteins; 11. Membrane proteins; 12. Crystallins and cataracts; 13. Sickle hemoglobin and sickle cell anemia; 14, Alzheimer's disease; Index.

  20. DNA microarray analysis of the epithelial-mesenchymal transition of mesothelial cells in a rat model of peritoneal dialysis.

    PubMed

    Imai, Toshimi; Hirahara, Ichiro; Morishita, Yoshiyuki; Onishi, Akir; Inoue, Makoto; Muto, Shigeaki; Kusano, Eiji

    2011-01-01

    Long-term peritoneal dialysis induces peritoneal hyperpermeability, and the subsequent loss of ultra-filtration causes patients to discontinue peritoneal dialysis. Glucose degradation products (GDPs) in peritoneal dialysis fluids (PDFs) are probably one of the primary causes for peritoneal injury. In the present study, we used a transcriptome analysis to determine the mechanism of peritoneal injury by GDPs. Rats were administered 20 mmol/L methylglyoxal (MGO) in PDF or 20 mmol/L formaldehyde in PDF (100 mL/kg) intraperitoneally for 21 days. The peritoneal membrane in rats that received MGO showed increased thickness and fibrosis. Mesenchymal-like cells over-proliferated on the surface of the peritoneum. A DNA microarray analysis revealed that the expression of 168 genes had increased by more than a factor of 4. The upregulated genes included those that code for extracellular matrix components (such as types III and lV collagen, among others), cell division cycle 42 (Cdc42), an enabled/vasodilator-stimulated phosphoprotein-like protein [Ena/VASP (Evl)], and actin-related protein 2/3 complex subunits (Arp2/3). In conclusion, a rat model of peritoneal injury by GDPs induced mesothelial cells to redifferentiate and proliferate, with upregulation of Cdc42, the Evl Ena/VASP, and Arp2/3, suggesting that GDPs induce fibrous thickening of the peritoneal membrane by redifferentiation of mesothelial cells, resulting in hyperpermeability of the peritoneum. PMID:22073821

  1. TLR4 inhibitor attenuates amyloid-β-induced angiogenic and inflammatory factors in ARPE-19 cells: Implications for age-related macular degeneration.

    PubMed

    Chen, Li; Bai, Yujing; Zhao, Min; Jiang, Yanrong

    2016-04-01

    Subretinally-deposited amyloid-β (Aβ) is an important factor in age‑related macular degradation (AMD) often leading to irreversible blindness in the elderly population. The molecular mechanism underlying Aβ deposition during AMD remains unclear. The expression of inflammatory and angiogenic factors was examined by treatment of retinal pigment epithelial (RPE) cells with the oligomeric form of Aβ (OAβ1-42). Changes in the mRNA expression levels of various cytokines was detected by the QuantiGenePlex 6.0 Reagent system, and the protein expression level was determined by western blotting. Culture supernatants were detected using a multiplex cytokine assay and enzyme-linked immunosorbent assays. The in vitro tube formation was evaluated by a Matrigel assay. The present study highlights that OAβ1‑42 activates the toll-like receptor 4 (TLR4), myeloid differentiation factor 88 and phosphorylation nuclear factor-κB signaling pathway in RPE cells. Additionally, it increased the mRNA and protein expression of interleukin (IL)-6, IL-8, IL-33, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and angiopoietin 2. Furthermore, the TLR4 inhibitor (COBRA) attenuated the expression of inflammatory and angiogenesis factors, particularly IL-6, IL-8, IL-33, bFGF and VEGF. When human umbilical vein endothelial cells (HUVECs) were co-cultured with the COBRA-treated RPE cell culture supernatant the length of the endothelial cell network (measured by calculating tip cell lengths of endothelial cells) was impaired when compared with the HUVECs that were co‑cultured with the cell supernatant exposed to OAβ1‑42. These results suggest that the TLR4-associated pathway may be a potential target for the treatment of AMD. PMID:26936827

  2. Total protein

    MedlinePlus

    The total protein test measures the total amount of two classes of proteins found in the fluid portion of your ... nutritional problems, kidney disease or liver disease . If total protein is abnormal, you will need to have more ...

  3. Storage Proteins

    PubMed Central

    Fujiwara, Toru; Nambara, Eiji; Yamagishi, Kazutoshi; Goto, Derek B.; Naito, Satoshi

    2002-01-01

    Plants accumulate storage substances such as starch, lipids and proteins in certain phases of development. Storage proteins accumulate in both vegetative and reproductive tissues and serve as a reservoir to be used in later stages of plant development. The accumulation of storage protein is thus beneficial for the survival of plants. Storage proteins are also an important source of dietary plant proteins. Here, we summarize the genome organization and regulation of gene expression of storage protein genes in Arabidopsis. PMID:22303197

  4. Fucoidan protects ARPE-19 cells from oxidative stress via normalization of reactive oxygen species generation through the Ca²⁺-dependent ERK signaling pathway.

    PubMed

    Li, Xiaoxia; Zhao, Haiyan; Wang, Qingfa; Liang, Hongyan; Jiang, Xiaofeng

    2015-05-01

    Diabetic retinopathy (DR) is a common complication of diabetes mellitus (DM) and it is the main cause of loss of vision. In previous years, interest in the biological activities of marine organisms has intensified. The effect of fucoidan from the seaweed Fucus vesiculosus on the molecular mechanisms of numerous diseases has been studied, while to date, its effect on DR was yet to be investigated. Therefore, the aim of the present study was to evaluate the role of fucoidan in DR. The human retinal pigment epithelial cell line ARPE‑19 was exposed to high D‑glucose in the presence or absence of fucoidan. Cell viability was monitored using MTT and lactate dehydrogenase assays. The intracellular reactive oxygen species (ROS) generation was measured using fluorescence spectrophotometry. Cell apoptosis was measured by flow cytometry using Annexin V‑fluorescein isothiocyanate staining. Ca2+ influx was measured with a calcium imaging system and the activation of the extracellular signal‑regulated kinase (ERK) protein was evaluated using western blot analysis. The non‑toxic fucoidan protected ARPE‑19 cells from high glucose‑induced cell death and normalized high glucose‑induced generation of ROS. Fucoidan also inhibited high glucose‑induced cell apoptosis, as well as the Ca2+ influx and ERK1/2 phosphorylation in ARPE‑19 cells. Taken together, these findings indicated that fucoidan protects ARPE‑19 cells against high glucose‑induced oxidative damage via normalization of ROS generation through the Ca2+‑dependent ERK signaling pathway. PMID:25606812

  5. Wiskott-Aldrich syndrome proteins in the nucleus: aWASH with possibilities

    PubMed Central

    Verboon, Jeffrey M; Sugumar, Bina; Parkhurst, Susan M

    2015-01-01

    Actin and proteins that regulate its dynamics or interactions have well-established roles in the cytoplasm where they function as key components of the cytoskeleton to control diverse processes, including cellular infrastructure, cellular motility, cell signaling, and vesicle transport. Recent work has also uncovered roles for actin and its regulatory proteins in the nucleus, primarily in mechanisms governing gene expression. The Wiskott Aldrich Syndrome (WAS) family of proteins, comprising the WASP/N-WASP, SCAR/WAVE, WHAMM/JMY/WHAMY, and WASH subfamilies, function in the cytoplasm where they activate the Arp2/3 complex to form branched actin filaments. WAS proteins are present in the nucleus and have been implicated as transcriptional regulators. We found that Drosophila Wash, in addition to transcriptional effects, is involved in global nuclear architecture. Here we summarize the regulation and function of nuclear WAS proteins, and highlight how our work with Wash expands the possibilities for the functions of these proteins in the nucleus. PMID:26305109

  6. Mechanosensitive kinetic preference of actin-binding protein to actin filament

    NASA Astrophysics Data System (ADS)

    Inoue, Yasuhiro; Adachi, Taiji

    2016-04-01

    The kinetic preference of actin-binding proteins to actin filaments is altered by external forces on the filament. Such an altered kinetic preference is largely responsible for remodeling the actin cytoskeletal structure in response to intracellular forces. During remodeling, actin-binding proteins and actin filaments interact under isothermal conditions, because the cells are homeostatic. In such a temperature homeostatic state, we can rigorously and thermodynamically link the chemical potential of actin-binding proteins to stresses on the actin filaments. From this relationship, we can construct a physical model that explains the force-dependent kinetic preference of actin-binding proteins to actin filaments. To confirm the model, we have analyzed the mechanosensitive alternation of the kinetic preference of Arp2/3 and cofilin to actin filaments. We show that this model captures the qualitative responses of these actin-binding proteins to the forces, as observed experimentally. Moreover, our theoretical results demonstrate that, depending on the structural parameters of the binding region, actin-binding proteins can show different kinetic responses even to the same mechanical signal tension, in which the double-helix nature of the actin filament also plays a critical role in a stretch-twist coupling of the filament.

  7. Sensitivity of the position and variability of the eddy-driven jet and storm-track to different SST profiles in an aquaplanet general circulation model (Arpège)

    NASA Astrophysics Data System (ADS)

    Michel, C.; Rivière, G.

    2012-04-01

    SST fronts were recently shown to determine in large part the positions of the eddy-driven jet and storm-track. The aim of our study is to examine not only the position but also the variability of the eddy-driven jet using the aquaplanet GCM Arpège Climat in perpetual equinoctial conditions. To do this, different zonally uniform SST profiles are prescribed with idealized piecewise linear distributions which allow us to modify the midlatitudes SST gradient without changing the tropical SSTs. We then perform systematic analysis by modifying the strength and the latitude of the SST gradient as well as the width of the gradient zone. Results are the following for the storm-track: the more equatorward the SST gradient or the stronger the gradient, the stronger the eddy activity. Interpretations are easily explained in terms of changes in baroclinicity. The eddy-driven jet is located on the poleward side of the gradient zone and the distance between the two increases for a more poleward position of the SST gradient. Interpretations are given in terms of non-linear interactions between synoptic and planetary scales and more precisely in terms of anticyclonic/cyclonic wave breakings asymmetry. Finally, when the SST gradient is shifted poleward, the low-frequency variability of the eddy-driven jet (as defined by the first EOF of the zonal wind at 850 hPa) changes from a latitudinal shifting to a pulsing. When the SST gradient is close to the subtropical jet, a strengthening of the subtropical jet leads to a pulsing of the vertically averaged zonal wind while there are still latitudinal fluctuations of the eddy-driven jet. Observational evidences of such changes are discussed using ERA40 reanalysis especially in the Pacific/North American domain.

  8. Dietary Proteins

    MedlinePlus

    ... grains and beans. Proteins from meat and other animal products are complete proteins. This means they supply all of the amino acids the body can't make on its own. Most plant proteins are incomplete. You should eat different types of plant proteins every day to get ...

  9. Protein Analysis

    NASA Astrophysics Data System (ADS)

    Chang, Sam K. C.

    Proteins are an abundant component in all cells, and almost all except storage proteins are important for biological functions and cell structure. Food proteins are very complex. Many have been purified and characterized. Proteins vary in molecular mass, ranging from approximately 5000 to more than a million Daltons. They are composed of elements including hydrogen, carbon, nitrogen, oxygen, and sulfur. Twenty α-amino acids are the building blocks of proteins; the amino acid residues in a protein are linked by peptide bonds. Nitrogen is the most distinguishing element present in proteins. However, nitrogen content in various food proteins ranges from 13.4 to 19.1% (1) due to the variation in the specific amino acid composition of proteins. Generally, proteins rich in basic amino acids contain more nitrogen.

  10. Protective effects of the galectin-1 protein on in vivo and in vitro models of ocular inflammation

    PubMed Central

    Zanon, Caroline de Freitas; Sonehara, Nathália Martins; Girol, Ana Paula; Gil, Cristiane Damas

    2015-01-01

    Purpose Galectin-1 (Gal-1) is a β-galactoside-binding protein with diverse biological activities in the pathogenesis of inflammation but has been poorly investigated in terms of ocular inflammation. In the present study, we monitored the anti-inflammatory effects of Gal-1 using the in vivo rodent model of endotoxin-induced uveitis (EIU) and in vitro assays with human RPE (ARPE-19) cells. Methods For this purpose, EIU was induced by subcutaneous sterile saline injection of 0.1 ml of lipopolysaccharide (LPS, 1 mg/Kg) in the rat paw, which was maintained under these conditions for 24 h. The therapeutic efficacy of recombinant Gal-1 (rGal-1) was tested in the EIU animals by intraperitoneal inoculation (3 µg/100 µl per animal) 15 min after the LPS injection. In vitro studies were performed using LPS-stimulated ARPE-19 cells (10 μg/ml) for 2, 8, 24 and 48 h, treated or not with rGal-1 (4 μg/ml) or dexamethasone (Dex, 1.0 μM). Results Gal-1 treatment attenuated the histopathological manifestation of EIU via the inhibition of polymorphonuclear cells (PMN) infiltration in the eye and by causing an imbalance in adhesion molecule expression and suppressing interleukin (IL)-1β, IL-6, and monocyte chemotactic protein-1 (MCP-1) productions. Immunohistochemical and western blotting analyses revealed significant upregulation of Gal-1 in the eyes induced by EIU after 24 h. In the retina, there was no difference in the Gal-1 expression, which was high in all groups, demonstrating its structural role in this region. To better understand the effects of Gal-1 in the retina, in vitro studies were performed using ARPE-19 cells. Ultrastructural immunocytochemical analyses showed decreased levels of endogenous Gal-1 in LPS-stimulated cells (24 h), while Dex treatment upregulated this protein. The protective effects of rGal-1 on LPS-stimulated cells were associated with the significant reduction of the release of cytokines (IL-8 and IL-6), similar to Dex treatment. Furthermore, r

  11. Crystal structure of a nuclear actin ternary complex.

    PubMed

    Cao, Tingting; Sun, Lingfei; Jiang, Yuxiang; Huang, Shanjin; Wang, Jiawei; Chen, Zhucheng

    2016-08-01

    Actin polymerizes and forms filamentous structures (F-actin) in the cytoplasm of eukaryotic cells. It also exists in the nucleus and regulates various nucleic acid transactions, particularly through its incorporation into multiple chromatin-remodeling complexes. However, the specific structure of actin and the mechanisms that regulate its polymeric nature inside the nucleus remain unknown. Here, we report the crystal structure of nuclear actin (N-actin) complexed with actin-related protein 4 (Arp4) and the helicase-SANT-associated (HSA) domain of the chromatin remodeler Swr1. The inner face and barbed end of N-actin are sequestered by interactions with Arp4 and the HSA domain, respectively, which prevents N-actin from polymerization and binding to many actin regulators. The two major domains of N-actin are more twisted than those of globular actin (G-actin), and its nucleotide-binding pocket is occluded, freeing N-actin from binding to and regulation by ATP. These findings revealed the salient structural features of N-actin that distinguish it from its cytoplasmic counterpart and provide a rational basis for its functions and regulation inside the nucleus. PMID:27457955

  12. The reorganization of actin filaments is required for vacuolar fusion of guard cells during stomatal opening in Arabidopsis.

    PubMed

    Li, Li-Juan; Ren, Fei; Gao, Xin-Qi; Wei, Peng-Cheng; Wang, Xue-Chen

    2013-02-01

    The reorganization of actin filaments (AFs) and vacuoles in guard cells is involved in the regulation of stomatal movement. However, it remains unclear whether there is any interaction between the reorganization of AFs and vacuolar changes during stomatal movement. Here, we report the relationship between the reorganization of AFs and vacuolar fusion revealed in pharmacological experiments, and characterizing stomatal opening in actin-related protein 2 (arp2) and arp3 mutants. Our results show that cytochalasin-D-induced depolymerization or phalloidin-induced stabilization of AFs leads to an increase in small unfused vacuoles during stomatal opening in wild-type (WT) Arabidopsis plants. Light-induced stomatal opening is retarded and vacuolar fusion in guard cells is impaired in the mutants, in which the reorganization and the dynamic parameters of AFs are aberrant compared with those of the WT. In WT, AFs tightly surround the small separated vacuoles, forming a ring that encircles the boundary membranes of vacuoles partly fused during stomatal opening. In contrast, in the mutants, most AFs and actin patches accumulate abnormally around the nuclei of the guard cells, which probably further impair vacuolar fusion and retard stomatal opening. Our results suggest that the reorganization of AFs regulates vacuolar fusion in guard cells during stomatal opening. PMID:22891733

  13. The Diaphanous-Related Formins Promote Protrusion Formation and Cell-to-Cell Spread of Listeria monocytogenes

    PubMed Central

    Fattouh, Ramzi; Kwon, Hyunwoo; Czuczman, Mark A.; Copeland, John W.; Pelletier, Laurence; Quinlan, Margot E.; Muise, Aleixo M.; Higgins, Darren E.; Brumell, John H.

    2015-01-01

    The Gram-positive bacterium Listeria monocytogenes is a facultative intracellular pathogen whose virulence depends on its ability to spread from cell to cell within an infected host. Although the actin-related protein 2/3 (Arp2/3) complex is necessary and sufficient for Listeria actin tail assembly, previous studies suggest that other actin polymerization factors, such as formins, may participate in protrusion formation. Here, we show that Arp2/3 localized to only a minor portion of the protrusion. Moreover, treatment of L. monocytogenes–infected HeLa cells with a formin FH2-domain inhibitor significantly reduced protrusion length. In addition, the Diaphanous-related formins 1–3 (mDia1–3) localized to protrusions, and knockdown of mDia1, mDia2, and mDia3 substantially decreased cell-to-cell spread of L. monocytogenes. Rho GTPases are known to be involved in formin activation. Our studies also show that knockdown of several Rho family members significantly influenced bacterial cell-to-cell spread. Collectively, these findings identify a Rho GTPase–formin network that is critically involved in the cell-to-cell spread of L. monocytogenes. PMID:25281757

  14. The diaphanous-related formins promote protrusion formation and cell-to-cell spread of Listeria monocytogenes.

    PubMed

    Fattouh, Ramzi; Kwon, Hyunwoo; Czuczman, Mark A; Copeland, John W; Pelletier, Laurence; Quinlan, Margot E; Muise, Aleixo M; Higgins, Darren E; Brumell, John H

    2015-04-01

    The Gram-positive bacterium Listeria monocytogenes is a facultative intracellular pathogen whose virulence depends on its ability to spread from cell to cell within an infected host. Although the actin-related protein 2/3 (Arp2/3) complex is necessary and sufficient for Listeria actin tail assembly, previous studies suggest that other actin polymerization factors, such as formins, may participate in protrusion formation. Here, we show that Arp2/3 localized to only a minor portion of the protrusion. Moreover, treatment of L. monocytogenes-infected HeLa cells with a formin FH2-domain inhibitor significantly reduced protrusion length. In addition, the Diaphanous-related formins 1-3 (mDia1-3) localized to protrusions, and knockdown of mDia1, mDia2, and mDia3 substantially decreased cell-to-cell spread of L. monocytogenes. Rho GTPases are known to be involved in formin activation. Our studies also show that knockdown of several Rho family members significantly influenced bacterial cell-to-cell spread. Collectively, these findings identify a Rho GTPase-formin network that is critically involved in the cell-to-cell spread of L. monocytogenes. PMID:25281757

  15. Phylogenetic Analysis Identifies Many Uncharacterized Actin-like Proteins (Alps) in Bacteria: Regulated Polymerization, Dynamic Instability, and Treadmilling in Alp7A

    PubMed Central

    Derman, Alan I.; Becker, Eric C.; Truong, Bao D.; Fujioka, Akina; Tucey, Timothy M.; Erb, Marcella L.; Patterson, Paula C.; Pogliano, Joe

    2010-01-01

    Summary Actin, one of the most abundant proteins in the eukaryotic cell, also has an abundance of relatives in the eukaryotic proteome. To date though, only five families of actins have been characterized in bacteria. We have conducted a phylogenetic search and uncovered more than 35 highly divergent families of actin-like proteins (Alps) in bacteria. Their genes are found primarily on phage genomes, on plasmids, and on integrating conjugative elements, and are likely to be involved in a variety of functions. We characterize three Alps and find that all form filaments in the cell. The filaments of Alp7A, a plasmid partitioning protein and one of the most divergent of the Alps, display dynamic instability and also treadmill. Alp7A requires other elements from the plasmid to assemble into dynamic polymers in the cell. Our findings suggest that most if not all of the Alps are indeed actin relatives, and that actin is very well represented in bacteria. PMID:19602153

  16. Role of cortactin in dynamic actin remodeling events in gonadotrope cells.

    PubMed

    Navratil, Amy M; Dozier, Melissa G; Whitesell, Jennifer D; Clay, Colin M; Roberson, Mark S

    2014-02-01

    GnRH induces marked activation of the actin cytoskeleton in gonadotropes; however, the physiological consequences and cellular mechanisms responsible have yet to be fully elucidated. The current studies focus on the actin scaffolding protein cortactin. Using the gonadotrope-derived αT3-1 cell line, we found that cortactin is phosphorylated at Y(421), S(405), and S(418) in a time-dependent manner in response to the GnRH agonist buserelin (GnRHa). GnRHa induced translocation of cortactin to the leading edge of the plasma membrane where it colocalizes with actin and actin-related protein 3 (Arp3). Incubation of αT3-1 cells with the c-src inhibitor phosphoprotein phosphatase 1, blocked tyrosine phosphorylation of cortactin, reduced cortactin association with Arp3, and blunted actin reorganization in response to GnRHa. Additionally, we used RNA silencing strategies to knock down cortactin in αT3-1 cells. Knockdown of cortactin blocked the ability of αT3-1 cells to generate filopodia, lamellipodia, and membrane ruffles in response to GnRHa. We show that lamellipodia and filopodia are capable of LHβ mobilization in primary pituitary culture after GnRHa treatment, and disruption of these structures using jasplakinolide reduces LH secretion. Collectively, our findings suggest that after GnRHa activation, src activity leads to tyrosine phosphorylation of cortactin, which facilitates its association with Arp3 to engage the actin cytoskeleton. The reorganization of actin by cortactin potentially underlies GnRHa-induced secretory events within αT3-1 cells. PMID:24274984

  17. Diffusion of GPI-anchored proteins is influenced by the activity of dynamic cortical actin

    PubMed Central

    Saha, Suvrajit; Lee, Il-Hyung; Polley, Anirban; Groves, Jay T.; Rao, Madan; Mayor, Satyajit

    2015-01-01

    Molecular diffusion at the surface of living cells is believed to be predominantly driven by thermal kicks. However, there is growing evidence that certain cell surface molecules are driven by the fluctuating dynamics of cortical cytoskeleton. Using fluorescence correlation spectroscopy, we measure the diffusion coefficient of a variety of cell surface molecules over a temperature range of 24–37°C. Exogenously incorporated fluorescent lipids with short acyl chains exhibit the expected increase of diffusion coefficient over this temperature range. In contrast, we find that GPI-anchored proteins exhibit temperature-independent diffusion over this range and revert to temperature-dependent diffusion on cell membrane blebs, in cells depleted of cholesterol, and upon acute perturbation of actin dynamics and myosin activity. A model transmembrane protein with a cytosolic actin-binding domain also exhibits the temperature-independent behavior, directly implicating the role of cortical actin. We show that diffusion of GPI-anchored proteins also becomes temperature dependent when the filamentous dynamic actin nucleator formin is inhibited. However, changes in cortical actin mesh size or perturbation of branched actin nucleator Arp2/3 do not affect this behavior. Thus cell surface diffusion of GPI-anchored proteins and transmembrane proteins that associate with actin is driven by active fluctuations of dynamic cortical actin filaments in addition to thermal fluctuations, consistent with expectations from an “active actin-membrane composite” cell surface. PMID:26378258

  18. Phase transitions of multivalent proteins can promote clustering of membrane receptors

    PubMed Central

    Banjade, Sudeep; Rosen, Michael K

    2014-01-01

    Clustering of proteins into micrometer-sized structures at membranes is observed in many signaling pathways. Most models of clustering are specific to particular systems, and relationships between physical properties of the clusters and their molecular components are not well understood. We report biochemical reconstitution on supported lipid bilayers of protein clusters containing the adhesion receptor Nephrin and its cytoplasmic partners, Nck and N-WASP. With Nephrin attached to the bilayer, multivalent interactions enable these proteins to polymerize on the membrane surface and undergo two-dimensional phase separation, producing micrometer-sized clusters. Dynamics and thermodynamics of the clusters are modulated by the valencies and affinities of the interacting species. In the presence of the Arp2/3 complex, the clusters assemble actin filaments, suggesting that clustering of regulatory factors could promote local actin assembly at membranes. Interactions between multivalent proteins could be a general mechanism for cytoplasmic adaptor proteins to organize membrane receptors into micrometer-scale signaling zones. DOI: http://dx.doi.org/10.7554/eLife.04123.001 PMID:25321392

  19. Planar Cell Polarity (PCP) Protein Vangl2 Regulates Ectoplasmic Specialization Dynamics via Its Effects on Actin Microfilaments in the Testes of Male Rats.

    PubMed

    Chen, Haiqi; Mruk, Dolores D; Lee, Will M; Cheng, C Yan

    2016-05-01

    Planar cell polarity (PCP) proteins confer polarization of a field of cells (eg, elongating/elongated spermatids) within the plane of an epithelium such as the seminiferous epithelium of the tubule during spermatogenesis. In adult rat testes, Sertoli and germ cells were found to express PCP core proteins (eg, Van Gogh-like 2 [Vangl2]), effectors, ligands, and signaling proteins. Vangl2 expressed predominantly by Sertoli cells was localized at the testis-specific, actin-rich ectoplasmic specialization (ES) at the Sertoli-spermatid interface in the adluminal compartment and also Sertoli-Sertoli interface at the blood-testis barrier (BTB) and structurally interacted with actin, N-cadherin, and another PCP/polarity protein Scribble. Vangl2 knockdown (KD) by RNA interference in Sertoli cells cultured in vitro with an established tight junction-permeability barrier led to BTB tightening, whereas its overexpression using a full-length cDNA construct perturbed the barrier function. These changes were mediated through an alteration on the organization actin microfilaments at the ES in Sertoli cells, involving actin-regulatory proteins, epidermal growth factor receptor pathway substrate 8, actin-related protein 3, and Scribble, which in turn affected the function of adhesion protein complexes at the ES during the epithelial cycle of spermatogenesis. Using Polyplus in vivo-jetPEI reagent as a transfection medium to silence Vangl2 in the testis in vivo by RNA interference with high efficacy, Vangl2 KD led to changes in F-actin organization at the ES in the epithelium, impeding spermatid and phagosome transport and spermatid polarity, meiosis, and BTB dynamics. For instance, step 19 spermatids remained embedded in the epithelium alongside with step 9 and 10 spermatids in stages IX-X tubules. In summary, the PCP protein Vangl2 is an ES regulator through its effects on actin microfilaments in the testis. PMID:26990065

  20. Total protein

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/003483.htm Total protein To use the sharing features on this page, please enable JavaScript. The total protein test measures the total amount of two classes ...

  1. Whey Protein

    MedlinePlus

    ... shows that taking whey protein in combination with strength training increases lean body mass, strength, and muscle size. ... grams/kg of whey protein in combination with strength training for 6-10 weeks. For HIV/AIDS-related ...

  2. Protein Microarrays

    NASA Astrophysics Data System (ADS)

    Ricard-Blum, S.

    Proteins are key actors in the life of the cell, involved in many physiological and pathological processes. Since variations in the expression of messenger RNA are not systematically correlated with variations in the protein levels, the latter better reflect the way a cell functions. Protein microarrays thus supply complementary information to DNA chips. They are used in particular to analyse protein expression profiles, to detect proteins within complex biological media, and to study protein-protein interactions, which give information about the functions of those proteins [3-9]. They have the same advantages as DNA microarrays for high-throughput analysis, miniaturisation, and the possibility of automation. Section 18.1 gives a brief overview of proteins. Following this, Sect. 18.2 describes how protein microarrays can be made on flat supports, explaining how proteins can be produced and immobilised on a solid support, and discussing the different kinds of substrate and detection method. Section 18.3 discusses the particular format of protein microarrays in suspension. The diversity of protein microarrays and their applications are then reported in Sect. 18.4, with applications to therapeutics (protein-drug interactions) and diagnostics. The prospects for future developments of protein microarrays are then outlined in the conclusion. The bibliography provides an extensive list of reviews and detailed references for those readers who wish to go further in this area. Indeed, the aim of the present chapter is not to give an exhaustive or detailed analysis of the state of the art, but rather to provide the reader with the basic elements needed to understand how proteins are designed and used.

  3. Protein Structure

    ERIC Educational Resources Information Center

    Asmus, Elaine Garbarino

    2007-01-01

    Individual students model specific amino acids and then, through dehydration synthesis, a class of students models a protein. The students clearly learn amino acid structure, primary, secondary, tertiary, and quaternary structure in proteins and the nature of the bonds maintaining a protein's shape. This activity is fun, concrete, inexpensive and…

  4. Protein folds and protein folding

    PubMed Central

    Schaeffer, R. Dustin; Daggett, Valerie

    2011-01-01

    The classification of protein folds is necessarily based on the structural elements that distinguish domains. Classification of protein domains consists of two problems: the partition of structures into domains and the classification of domains into sets of similar structures (or folds). Although similar topologies may arise by convergent evolution, the similarity of their respective folding pathways is unknown. The discovery and the characterization of the majority of protein folds will be followed by a similar enumeration of available protein folding pathways. Consequently, understanding the intricacies of structural domains is necessary to understanding their collective folding pathways. We review the current state of the art in the field of protein domain classification and discuss methods for the systematic and comprehensive study of protein folding across protein fold space via atomistic molecular dynamics simulation. Finally, we discuss our large-scale Dynameomics project, which includes simulations of representatives of all autonomous protein folds. PMID:21051320

  5. Involvement of protein kinase C in phagocytosis of human retinal pigment epithelial cells and induction of matrix metalloproteinase secretion.

    PubMed

    Irschick, Eveline U; Haas, Gertrud; Troger, Josef; Ueberall, Florian; Huemer, Hartwig P

    2009-10-01

    Protein kinase C (PKC) is involved in cell activation. We investigated PKC-mediated pathways and secretion of matrix metalloproteinases (MMPs) in phagocytosis by human retinal pigment epithelial cells (RPE). We used time-resolved fluorometry for europium-labeled microsphere uptake and gel zymography to assay the influence of PKC modulators. PKC inhibitors blocked phagocytosis by RPE. ARPE-19, a human RPE-cell line, showed reduced secretion of MMP-2, although MMP-9 secretion by PKC activation was conserved in both cell types, namely in the primary RPEs and in the RPE-cell line. Particle uptake by RPE cells requires activation of PKC; the use of PKC inhibitors as new anticancer drugs may possibly cause ocular side-effects. PMID:18641922

  6. Actin-associated protein palladin is required for migration behavior and differentiation potential of C2C12 myoblast cells

    SciTech Connect

    Nguyen, Ngoc Uyen Nhi; Liang, Vincent Roderick; Wang, Hao-Ven

    2014-09-26

    Highlights: • Palladin is involved in myogenesis in vitro. • Palladin knockdown by siRNA increases myoblast proliferation, viability and differentiation. • Palladin knockdown decreases C2C12 myoblast migration ability. - Abstract: The actin-associated protein palladin has been shown to be involved in differentiation processes in non-muscle tissues. However, but its function in skeletal muscle has rarely been studied. Palladin plays important roles in the regulation of diverse actin-related signaling in a number of cell types. Since intact actin-cytoskeletal remodeling is necessary for myogenesis, in the present study, we pursue to investigate the role of actin-associated palladin in skeletal muscle differentiation. Palladin in C2C12 myoblasts is knocked-down using specific small interfering RNA (siRNA). The results show that down-regulation of palladin decreased migratory activity of mouse skeletal muscle C2C12 myoblasts. Furthermore, the depletion of palladin enhances C2C12 vitality and proliferation. Of note, the loss of palladin promotes C2C12 to express the myosin heavy chain, suggesting that palladin has a role in the modulation of C2C12 differentiation. It is thus proposed that palladin is required for normal C2C12 myogenesis in vitro.

  7. Novel pentablock copolymer-based nanoparticulate systems for sustained protein delivery.

    PubMed

    Patel, Sulabh P; Vaishya, Ravi; Pal, Dhananjay; Mitra, Ashim K

    2015-04-01

    The design, synthesis, and application of novel biodegradable and biocompatible pentablock (PB) copolymers, i.e., polyglycolic acid-polycaprolactone-polyethylene glycol-polycaprolactone-polyglycolic acid (PGA-PCL-PEG-PCL-PGA) and polylactic acid-polycaprolactone-polyethylene glycol-polycaprolactone-polylactic acid (PLA-PCL-PEG-PCL-PLA) for sustained protein delivery, are reported. The PB copolymers can be engineered to generate sustained delivery of protein therapeutics to the posterior segment of the eye. PB copolymers with different block arrangements and molecular weights were synthesized by ring-opening polymerization and characterized by proton nuclear magnetic resonance ((1)H-NMR), gel permeation chromatography (GPC), and X-ray diffraction (XRD) spectroscopy. Immunoglobulin G (IgG) was selected as a model protein due to its structural similarity to bevacizumab. The influence of polymer molecular weight, composition, and isomerism on formulation parameters such as entrapment efficiency, drug loading, and in vitro release profile was delineated. Crystallinity and molecular weight of copolymers exhibited a substantial effect on formulation parameters. A secondary structure of released IgG was confirmed by circular dichroism (CD) spectroscopy. In vitro cytotoxicity, cell viability, and biocompatibility studies performed on human retinal pigment epithelial cells (ARPE-19) and/or macrophage cell line (RAW 264.7) demonstrated PB copolymers to be excellent biomaterials. Novel PB polymers may be the answer to the unmet need of a sustained release protein formulation. PMID:25319053

  8. Are cobaltates conventional? An ARPES viewpoint

    SciTech Connect

    Hasan, M.Z. . E-mail: mzhasan@Princeton.edu; Qian, D.; Foo, M.L.; Cava, R.J.

    2006-07-15

    Recently discovered class of cobaltate superconductors (Na{sub 0.3}CoO{sub 2}.nH{sub 2}O) is a novel realization of interacting quantum electron system in a triangular network with low-energy degrees of freedom. We employ angle-resolved photoemission spectroscopy to study the quasiparticle parameters in the parent superconductors. Results reveal a large hole-like Fermi surface generated by the crossing of heavy quasiparticles. The measured quasiparticle parameters collectively suggest two orders of magnitude departure from the conventional weak coupling (such as Al) Bardeen-Cooper-Schrieffer electron dynamics paradigm and unveils cobaltates as a rather hidden class of relatively high temperature superconductors. These parameters also form the basis for a microscopic Hamiltonian of the system.

  9. Large scale systematic proteomic quantification from non-metastatic to metastatic colorectal cancer

    NASA Astrophysics Data System (ADS)

    Yin, Xuefei; Zhang, Yang; Guo, Shaowen; Jin, Hong; Wang, Wenhai; Yang, Pengyuan

    2015-07-01

    A systematic proteomic quantification of formalin-fixed, paraffin-embedded (FFPE) colorectal cancer tissues from stage I to stage IIIC was performed in large scale. 1017 proteins were identified with 338 proteins in quantitative changes by label free method, while 341 proteins were quantified with significant expression changes among 6294 proteins by iTRAQ method. We found that proteins related to migration expression increased and those for binding and adherent decreased during the colorectal cancer development according to the gene ontology (GO) annotation and ingenuity pathway analysis (IPA). The integrin alpha 5 (ITA5) in integrin family was focused, which was consistent with the metastasis related pathway. The expression level of ITA5 decreased in metastasis tissues and the result has been further verified by Western blotting. Another two cell migration related proteins vitronectin (VTN) and actin-related protein (ARP3) were also proved to be up-regulated by both mass spectrometry (MS) based quantification results and Western blotting. Up to now, our result shows one of the largest dataset in colorectal cancer proteomics research. Our strategy reveals a disease driven omics-pattern for the metastasis colorectal cancer.

  10. Protein Dynamics

    NASA Astrophysics Data System (ADS)

    Frauenfelder, Hans

    2011-03-01

    Proteins combine properties of solids, liquids, and glasses. Schrödinger anticipated the main features of biomolecules long ago by stating that they had to be solid-like, but able to assume many different conformations. Indeed proteins can assume a gigantic number of conformational substates with the same primary sequence but different conformations. The different substates are described as craters in a very-high-dimensional energy landscape. The energy landscape is organized in a hierarchy of tiers, craters within craters within craters. Protein motions are pictured as transition between substates - jumps from crater to crater. Initially we assumed that these jumps were controlled by internal barriers between substates, but experiments have shown that nature selected a different approach. Proteins are surrounded by one to two layers of water and are embedded in a bulk solvent. Structural motions of the protein are controlled by the alpha fluctuations in the solvent surrounding the protein. Some internal motions most likely involving side chains are controlled electrostatically by beta fluctuations in the hydration shell. The dynamics of proteins is consequently dominated by the environment (H. Frauenfelder et al. PNAS 106, 5129 (2009). One can speculate that this organization permits exchange of information among biomolecules. The energy landscape is not just organized into two tiers, alpha and beta, but cryogenic experiments have revealed more tiers and protein more properties similar to that of glasses. While proteins function at ambient temperatures, cryogenic studies are necessary to understand the physics relevant for biology.

  11. Deoxyhypusine Modification of Eukaryotic Translation Initiation Factor 5A (eIF5A) Is Essential for Trypanosoma brucei Growth and for Expression of Polyprolyl-containing Proteins*

    PubMed Central

    Nguyen, Suong; Leija, Chrisopher; Kinch, Lisa; Regmi, Sandesh; Li, Qiong; Grishin, Nick V.; Phillips, Margaret A.

    2015-01-01

    The eukaryotic protozoan parasite Trypanosoma brucei is the causative agent of human African trypanosomiasis. Polyamine biosynthesis is essential in T. brucei, and the polyamine spermidine is required for synthesis of a novel cofactor called trypanothione and for deoxyhypusine modification of eukaryotic translation initiation factor 5A (eIF5A). eIF5A promotes translation of proteins containing polyprolyl tracts in mammals and yeast. To evaluate the function of eIF5A in T. brucei, we used RNA interference (RNAi) to knock down eIF5A levels and found that it is essential for T. brucei growth. The RNAi-induced growth defect was complemented by expression of wild-type human eIF5A but not by a Lys-50 mutant that blocks modification by deoxyhypusine. Bioinformatics analysis showed that 15% of the T. brucei proteome contains 3 or more consecutive prolines and that actin-related proteins and cysteine proteases were highly enriched in the group. Steady-state protein levels of representative proteins containing 9 consecutive prolines that are involved in actin assembly (formin and CAP/Srv2p) were significantly reduced by knockdown of eIF5A. Several T. brucei polyprolyl proteins are involved in flagellar assembly. Knockdown of TbeIF5A led to abnormal cell morphologies and detached flagella, suggesting that eIF5A is important for translation of proteins needed for these processes. Potential specialized functions for eIF5A in T. brucei in translation of variable surface glycoproteins were also uncovered. Inhibitors of deoxyhypusination would be expected to cause a pleomorphic effect on multiple cell processes, suggesting that deoxyhypusine/hypusine biosynthesis could be a promising drug target in not just T. brucei but in other eukaryotic pathogens. PMID:26082486

  12. Interfacial Protein-Protein Associations

    PubMed Central

    Langdon, Blake B.; Kastantin, Mark; Walder, Robert; Schwartz, Daniel K.

    2014-01-01

    While traditional models of protein adsorption focus primarily on direct protein-surface interactions, recent findings suggest that protein-protein interactions may play a central role. Using high-throughput intermolecular resonance energy transfer (RET) tracking, we directly observed dynamic, protein-protein associations of bovine serum albumin on poly(ethylene glycol) modified surfaces. The associations were heterogeneous and reversible, and associating molecules resided on the surface for longer times. The appearance of three distinct RET states suggested a spatially heterogeneous surface – with areas of high protein density (i.e. strongly-interacting clusters) coexisting with mobile monomers. Distinct association states exhibited characteristic behavior, i.e. partial-RET (monomer-monomer) associations were shorter-lived than complete-RET (protein-cluster) associations. While the fractional surface area covered by regions with high protein density (i.e. clusters) increased with increasing concentration, the distribution of contact times between monomers and clusters was independent of solution concentration, suggesting that associations were a local phenomenon, and independent of the global surface coverage. PMID:24274729

  13. The human IgA-Fc alpha receptor interaction and its blockade by streptococcal IgA-binding proteins.

    PubMed

    Woof, J M

    2002-08-01

    IgA plays a key role in immune defence of the mucosal surfaces. IgA can trigger elimination mechanisms against pathogens through the interaction of its Fc region with Fc alpha Rs (receptors specific for the Fc region of IgA) present on neutrophils, macrophages, monocytes and eosinophils. The human Fc alpha R (CD89) shares homology with receptors specific for the Fc region of IgG (Fc gamma Rs) and IgE (Fc epsilon RIs), but is a more distantly related member of the receptor family. CD89 interacts with residues lying at the interface of the two domains of IgA Fc, a site quite distinct from the homologous regions at the top of IgG and IgE Fc recognized by Fc gamma R and Fc epsilon RI respectively. Certain pathogenic bacteria express surface proteins that bind to human IgA Fc. Experiments with domain-swap antibodies and mutant IgAs indicate that binding of three such proteins (Sir22 and Arp4 of Streptococcus pyogenes and beta protein of group B streptococci) depend on sites in the Fc interdomain region of IgA, the binding region also used by CD89. Further, we have found that the streptococcal proteins can inhibit interaction of IgA with CD89, and have thereby identified a mechanism by which a bacterial IgA-binding protein may modulate IgA effector function. PMID:12196121

  14. Phase Transitions in the Assembly of Multi-Valent Signaling Proteins

    PubMed Central

    Li, Pilong; Banjade, Sudeep; Cheng, Hui-Chun; Kim, Soyeon; Chen, Baoyu; Guo, Liang; Llaguno, Marc; Hollingsworth, Javoris V.; King, David S.; Banani, Salman F.; Russo, Paul S.; Jiang, Qiu-Xing; Nixon, B. Tracy; Rosen, Michael K.

    2012-01-01

    Cells are organized on length scales ranging from Angstroms to microns. However, the mechanisms by which Angstrom-scale molecular properties are translated to micron-scale macroscopic properties are not well understood. Here we show that interactions between diverse, synthetic multivalent macromolecules (including multi-domain proteins and RNA) produce sharp, liquid-liquid demixing phase separations, generating micron-sized liquid droplets in aqueous solution. This macroscopic transition corresponds to a molecular transition between small complexes and large, dynamic supramolecular polymers. The concentrations needed for phase transition are directly related to valency of the interacting species. In the case of the actin regulatory protein, neuronal Wiskott-Aldrich Syndrome Protein (N-WASP) interacting with its established biological partners Nck and phosphorylated nephrin1, the phase transition corresponds to a sharp increase in activity toward the actin nucleation factor, Arp2/3 complex. The transition is governed by the degree of phosphorylation of nephrin, explaining how this property of the system can be controlled to regulatory effect by kinases. The widespread occurrence of multivalent systems suggests that phase transitions are likely used to spatially organize and biochemically regulate information throughout biology. PMID:22398450

  15. Polarity protein Crumbs homolog-3 (CRB3) regulates ectoplasmic specialization dynamics through its action on F-actin organization in Sertoli cells

    PubMed Central

    Gao, Ying; Lui, Wing-yee; Lee, Will M.; Cheng, C. Yan

    2016-01-01

    Crumbs homolog 3 (or Crumbs3, CRB3) is a polarity protein expressed by Sertoli and germ cells at the basal compartment in the seminiferous epithelium. CRB3 also expressed at the blood-testis barrier (BTB), co-localized with F-actin, TJ proteins occludin/ZO-1 and basal ES (ectoplasmic specialization) proteins N-cadherin/β-catenin at stages IV-VII only. The binding partners of CRB3 in the testis were the branched actin polymerization protein Arp3, and the barbed end-capping and bundling protein Eps8, illustrating its possible role in actin organization. CRB3 knockdown (KD) by RNAi in Sertoli cells with an established tight junction (TJ)-permeability barrier perturbed the TJ-barrier via changes in the distribution of TJ- and basal ES-proteins at the cell-cell interface. These changes were the result of CRB3 KD-induced re-organization of actin microfilaments, in which actin microfilaments were truncated, and extensively branched, thereby destabilizing F-actin-based adhesion protein complexes at the BTB. Using Polyplus in vivo-jetPEI as a transfection medium with high efficiency for CRB3 KD in the testis, the CRB3 KD testes displayed defects in spermatid and phagosome transport, and also spermatid polarity due to a disruption of F-actin organization. In summary, CRB3 is an actin microfilament regulator, playing a pivotal role in organizing actin filament bundles at the ES. PMID:27358069

  16. Polarity protein Crumbs homolog-3 (CRB3) regulates ectoplasmic specialization dynamics through its action on F-actin organization in Sertoli cells.

    PubMed

    Gao, Ying; Lui, Wing-Yee; Lee, Will M; Cheng, C Yan

    2016-01-01

    Crumbs homolog 3 (or Crumbs3, CRB3) is a polarity protein expressed by Sertoli and germ cells at the basal compartment in the seminiferous epithelium. CRB3 also expressed at the blood-testis barrier (BTB), co-localized with F-actin, TJ proteins occludin/ZO-1 and basal ES (ectoplasmic specialization) proteins N-cadherin/β-catenin at stages IV-VII only. The binding partners of CRB3 in the testis were the branched actin polymerization protein Arp3, and the barbed end-capping and bundling protein Eps8, illustrating its possible role in actin organization. CRB3 knockdown (KD) by RNAi in Sertoli cells with an established tight junction (TJ)-permeability barrier perturbed the TJ-barrier via changes in the distribution of TJ- and basal ES-proteins at the cell-cell interface. These changes were the result of CRB3 KD-induced re-organization of actin microfilaments, in which actin microfilaments were truncated, and extensively branched, thereby destabilizing F-actin-based adhesion protein complexes at the BTB. Using Polyplus in vivo-jetPEI as a transfection medium with high efficiency for CRB3 KD in the testis, the CRB3 KD testes displayed defects in spermatid and phagosome transport, and also spermatid polarity due to a disruption of F-actin organization. In summary, CRB3 is an actin microfilament regulator, playing a pivotal role in organizing actin filament bundles at the ES. PMID:27358069

  17. Whey Protein

    MedlinePlus

    ... intolerance, for replacing or supplementing milk-based infant formulas, and for reversing weight loss and increasing glutathione ( ... allergic reactions compared to infants who receive standard formula. However, taking why protein might not be helpful ...

  18. 4-Hydroxy-7-oxo-5-heptenoic Acid (HOHA) Lactone is a Biologically Active Precursor for the Generation of 2-(ω-Carboxyethyl)pyrrole (CEP) Derivatives of Proteins and Ethanolamine Phospholipids.

    PubMed

    Wang, Hua; Linetsky, Mikhail; Guo, Junhong; Choi, Jaewoo; Hong, Li; Chamberlain, Amanda S; Howell, Scott J; Howes, Andrew M; Salomon, Robert G

    2015-05-18

    2-(ω-Carboxyethyl)pyrrole (CEP) derivatives of proteins were previously shown to have significant pathological and physiological relevance to age-related macular degeneration, cancer and wound healing. Previously, we showed that CEPs are generated in the reaction of ε-amino groups of protein lysyl residues with 1-palmityl-2-(4-hydroxy-7-oxo-5-heptenoyl)-sn-glycero-3-phosphatidylcholine (HOHA-PC), a lipid oxidation product uniquely generated by oxidative truncation of docosahexanenate-containing phosphatidylcholine. More recently, we found that HOHA-PC rapidly releases HOHA-lactone and 2-lyso-PC (t1/2 = 30 min at 37 °C) by nonenzymatic transesterification/deacylation. Now we report that HOHA-lactone reacts with Ac-Gly-Lys-OMe or human serum albumin to form CEP derivatives in vitro. Incubation of human red blood cell ghosts with HOHA-lactone generates CEP derivatives of membrane proteins and ethanolamine phospholipids. Quantitative analysis of the products generated in the reaction HOHA-PC with Ac-Gly-Lys-OMe showed that HOHA-PC mainly forms CEP-dipeptide that is not esterified to 2-lysophosphatidycholine. Thus, the HOHA-lactone pathway predominates over the direct reaction of HOHA-PC to produce the CEP-PC-dipeptide derivative. Myleoperoxidase/H2O2/NO2(-) promoted in vitro oxidation of either 1-palmityl-2-docosahexaneoyl-sn-glycero-3-phosphatidylcholine (DHA-PC) or docosahexaenoic acid (DHA) generates HOHA-lactone in yields of 0.45% and 0.78%, respectively. Lipid oxidation in human red blood cell ghosts also releases HOHA-lactone. Oxidative injury of ARPE-19 human retinal pigmented epithelial cells by exposure to H2O2 generated CEP derivatives. Treatment of ARPE-19 cells with HOHA-lactone generated CEP-modified proteins. Low (submicromolar), but not high, concentrations of HOHA-lactone promote increased vascular endothelial growth factor (VEGF) secretion by ARPE-19 cells. Therefore, HOHA-lactone not only serves as an intermediate for the generation of CEPs but

  19. Mechanical force-induced polymerization and depolymerization of F-actin at water/solid interfaces

    NASA Astrophysics Data System (ADS)

    Zhang, Xueqiang; Hu, Xiuyuan; Lei, Haozhi; Hu, Jun; Zhang, Yi

    2016-03-01

    Actin molecules are among the three main cytoskeleton proteins of cells and undergo rapid cycling to regulate critical processes such as endocytosis, cytokinesis, cell polarity, and cell morphogenesis. Although extensive studies have been carried out on the dynamics as well as biological functions of actin polymerization and depolymerization both in vivo and in vitro, the molecular mechanisms by which cells sense and respond to mechanical signals are not fully understood. In particular, little attention has been paid to the effect of a physical force that is exerted directly on the actin cytoskeleton. In this paper, we have explored how the mechanical force affects the actin polymerization and depolymerization behaviors at water/solid interfaces using an atomic force microscope (AFM) operated in liquid. By raster scanning an AFM probe on a substrate surface with a certain load, it was found that actin monomers could polymerize into filaments without the help of actin related proteins (ARPs). Further study indicated that actin monomers were inclined to form filaments only under a small scanning load. The polymerized actin filaments would be depolymerized when the mechanical force was stronger. A possible mechanism has been suggested to explain the mechanical force induced actin polymerization.Actin molecules are among the three main cytoskeleton proteins of cells and undergo rapid cycling to regulate critical processes such as endocytosis, cytokinesis, cell polarity, and cell morphogenesis. Although extensive studies have been carried out on the dynamics as well as biological functions of actin polymerization and depolymerization both in vivo and in vitro, the molecular mechanisms by which cells sense and respond to mechanical signals are not fully understood. In particular, little attention has been paid to the effect of a physical force that is exerted directly on the actin cytoskeleton. In this paper, we have explored how the mechanical force affects the actin

  20. Slit2N/Robo1 Inhibit HIV-gp120-Induced Migration and Podosome Formation in Immature Dendritic Cells by Sequestering LSP1 and WASp

    PubMed Central

    Prasad, Anil; Kuzontkoski, Paula M.; Shrivastava, Ashutosh; Zhu, Weiquan; Li, Dean Y.; Groopman, Jerome E.

    2012-01-01

    Cell-mediated transmission and dissemination of sexually-acquired human immunodeficiency virus 1 (HIV-1) in the host involves the migration of immature dendritic cells (iDCs). iDCs migrate in response to the HIV-1 envelope protein, gp120, and inhibiting such migration may limit the mucosal transmission of HIV-1. In this study, we elucidated the mechanism of HIV-1-gp120-induced transendothelial migration of iDCs. We found that gp120 enhanced the binding of Wiskott-Aldrich Syndrome protein (WASp) and the Actin-Related Protein 2/3 (Arp2/3) complex with β-actin, an interaction essential for the proper formation of podosomes, specialized adhesion structures required for the migration of iDCs through different tissues. We further identified Leukocyte-Specific Protein 1 (LSP1) as a novel component of the WASp-Arp2/3-β-actin complex. Pretreating iDCs with an active fragment of the secretory glycoprotein Slit2 (Slit2N) inhibited HIV-1-gp120-mediated migration and podosome formation, by inducing the cognate receptor Roundabout 1 (Robo1) to bind to and sequester WASp and LSP1 from β-actin. Slit2N treatment also inhibited Src signaling and the activation of several downstream molecules, including Rac1, Pyk2, paxillin, and CDC42, a major regulator of podosome formation. Taken together, our results support a novel mechanism by which Slit2/Robo1 may inhibit the HIV-1-gp120-induced migration of iDCs, thereby restricting dissemination of HIV-1 from mucosal surfaces in the host. PMID:23119100

  1. Formin 1 Regulates Ectoplasmic Specialization in the Rat Testis Through Its Actin Nucleation and Bundling Activity.

    PubMed

    Li, Nan; Mruk, Dolores D; Wong, Chris K C; Han, Daishu; Lee, Will M; Cheng, C Yan

    2015-08-01

    During spermatogenesis, developing spermatids and preleptotene spermatocytes are transported across the adluminal compartment and the blood-testis barrier (BTB), respectively, so that spermatids line up near the luminal edge to prepare for spermiation, whereas preleptotene spermatocytes enter the adluminal compartment to differentiate into late spermatocytes to prepare for meiosis I/II. These cellular events involve actin microfilament reorganization at the testis-specific, actin-rich Sertoli-spermatid and Sertoli-Sertoli cell junction called apical and basal ectoplasmic specialization (ES). Formin 1, an actin nucleation protein known to promote actin microfilament elongation and bundling, was expressed at the apical ES but limited to stage VII of the epithelial cycle, whereas its expression at the basal ES/BTB stretched from stage III to stage VI, diminished in stage VII, and was undetectable in stage VIII tubules. Using an in vitro model of studying Sertoli cell BTB function by RNA interference and biochemical assays to monitor actin bundling and polymerization activity, a knockdown of formin 1 in Sertoli cells by approximately 70% impeded the tight junction-permeability function. This disruptive effect on the tight junction barrier was mediated by a loss of actin microfilament bundling and actin polymerization capability mediated by changes in the localization of branched actin-inducing protein Arp3 (actin-related protein 3), and actin bundling proteins Eps8 (epidermal growth factor receptor pathway substrate 8) and palladin, thereby disrupting cell adhesion. Formin 1 knockdown in vivo was found to impede spermatid adhesion, transport, and polarity, causing defects in spermiation in which elongated spermatids remained embedded into the epithelium in stage IX tubules, mediated by changes in the spatiotemporal expression of Arp3, Eps8, and palladin. In summary, formin 1 is a regulator of ES dynamics. PMID:25901598

  2. Designed protein-protein association.

    PubMed

    Grueninger, Dirk; Treiber, Nora; Ziegler, Mathias O P; Koetter, Jochen W A; Schulze, Monika-Sarah; Schulz, Georg E

    2008-01-11

    The analysis of natural contact interfaces between protein subunits and between proteins has disclosed some general rules governing their association. We have applied these rules to produce a number of novel assemblies, demonstrating that a given protein can be engineered to form contacts at various points of its surface. Symmetry plays an important role because it defines the multiplicity of a designed contact and therefore the number of required mutations. Some of the proteins needed only a single side-chain alteration in order to associate to a higher-order complex. The mobility of the buried side chains has to be taken into account. Four assemblies have been structurally elucidated. Comparisons between the designed contacts and the results will provide useful guidelines for the development of future architectures. PMID:18187656

  3. EFC/F-BAR proteins and the N-WASP–WIP complex induce membrane curvature-dependent actin polymerization

    PubMed Central

    Takano, Kazunari; Toyooka, Kiminori; Suetsugu, Shiro

    2008-01-01

    Extended Fer-CIP4 homology (EFC)/FCH-BAR (F-BAR) domains generate and bind to tubular membrane structures of defined diameters that are involved in the formation and fission of endocytotic vesicles. Formin-binding protein 17 (FBP17) and Toca-1 contain EFC/F-BAR domains and bind to neural Wiskott–Aldrich syndrome protein (N-WASP), which links phosphatidylinositol (4,5)-bisphosphate (PIP2) and the Rho family GTPase Cdc42 to the Arp2/3 complex. The N-WASP–WASP-interacting protein (WIP) complex, a predominant form of N-WASP in cells, is known to be activated by Toca-1 and Cdc42. Here, we show that N-WASP–WIP complex-mediated actin polymerization is activated by phosphatidylserine-containing membranes depending on membrane curvature in the presence of Toca-1 or FBP17 and in the absence of Cdc42 and PIP2. Cdc42 further promoted the activation of actin polymerization by N-WASP–WIP. Toca-1 or FBP17 recruited N-WASP–WIP to the membrane. Conserved acidic residues near the SH3 domain of Toca-1 and FBP17 positioned the N-WASP–WIP to be spatially close to the membrane for activation of actin polymerization. Therefore, curvature-dependent actin polymerization is stimulated by spatially appropriate interactions of EFC/F-BAR proteins and the N-WASP–WIP complex with the membrane. PMID:18923421

  4. Eng2 is a component of a dynamic protein complex required for endocytic uptake in fission yeast.

    PubMed

    Encinar del Dedo, Javier; Idrissi, Fatima-Zahra; Arnáiz-Pita, Yolanda; James, Michael; Dueñas-Santero, Encarnación; Orellana-Muñoz, Sara; del Rey, Francisco; Sirotkin, Vladimir; Geli, M Isabel; Vázquez de Aldana, Carlos R

    2014-10-01

    Eng2 is a glucanase required for spore release, although it is also expressed during vegetative growth, suggesting that it might play other cellular functions. Its homology to the Saccharomyces cerevisiae Acf2 protein, previously shown to promote actin polymerization at endocytic sites in vitro, prompted us to investigate its role in endocytosis. Interestingly, depletion of Eng2 caused profound defects in endocytic uptake, which were not due to the absence of its glucanase activity. Analysis of the dynamics of endocytic proteins by fluorescence microscopy in the eng2Δ strain unveiled a previously undescribed phenotype, in which assembly of the Arp2/3 complex appeared uncoupled from the internalization of the endocytic coat and resulted in a fission defect. Strikingly also, we found that Eng2-GFP dynamics did not match the pattern of other endocytic proteins. Eng2-GFP localized to bright cytosolic spots that moved around the cellular poles and occasionally contacted assembling endocytic patches just before recruitment of Wsp1, the Schizosaccharomyces pombe WASP. Interestingly, Csh3-YFP, a WASP-interacting protein, interacted with Eng2 by co-immunoprecipitation and was recruited to Eng2 in bright cytosolic spots. Altogether, our work defines a novel endocytic functional module, which probably couples the endocytic coat to the actin module. PMID:25040903

  5. Protein Crystallization

    NASA Technical Reports Server (NTRS)

    Chernov, Alexander A.

    2005-01-01

    Nucleation, growth and perfection of protein crystals will be overviewed along with crystal mechanical properties. The knowledge is based on experiments using optical and force crystals behave similar to inorganic crystals, though with a difference in orders of magnitude in growing parameters. For example, the low incorporation rate of large biomolecules requires up to 100 times larger supersaturation to grow protein, rather than inorganic crystals. Nucleation is often poorly reproducible, partly because of turbulence accompanying the mixing of precipitant with protein solution. Light scattering reveals fluctuations of molecular cluster size, its growth, surface energies and increased clustering as protein ages. Growth most often occurs layer-by-layer resulting in faceted crystals. New molecular layer on crystal face is terminated by a step where molecular incorporation occurs. Quantitative data on the incorporation rate will be discussed. Rounded crystals with molecularly disordered interfaces will be explained. Defects in crystals compromise the x-ray diffraction resolution crucially needed to find the 3D atomic structure of biomolecules. The defects are immobile so that birth defects stay forever. All lattice defects known for inorganics are revealed in protein crystals. Contribution of molecular conformations to lattice disorder is important, but not studied. This contribution may be enhanced by stress field from other defects. Homologous impurities (e.g., dimers, acetylated molecules) are trapped more willingly by a growing crystal than foreign protein impurities. The trapped impurities induce internal stress eliminated in crystals exceeding a critical size (part of mni for ferritin, lysozyme). Lesser impurities are trapped from stagnant, as compared to the flowing, solution. Freezing may induce much more defects unless quickly amorphysizing intracrystalline water.

  6. Bacteriophage protein-protein interactions.

    PubMed

    Häuser, Roman; Blasche, Sonja; Dokland, Terje; Haggård-Ljungquist, Elisabeth; von Brunn, Albrecht; Salas, Margarita; Casjens, Sherwood; Molineux, Ian; Uetz, Peter

    2012-01-01

    Bacteriophages T7, λ, P22, and P2/P4 (from Escherichia coli), as well as ϕ29 (from Bacillus subtilis), are among the best-studied bacterial viruses. This chapter summarizes published protein interaction data of intraviral protein interactions, as well as known phage-host protein interactions of these phages retrieved from the literature. We also review the published results of comprehensive protein interaction analyses of Pneumococcus phages Dp-1 and Cp-1, as well as coliphages λ and T7. For example, the ≈55 proteins encoded by the T7 genome are connected by ≈43 interactions with another ≈15 between the phage and its host. The chapter compiles published interactions for the well-studied phages λ (33 intra-phage/22 phage-host), P22 (38/9), P2/P4 (14/3), and ϕ29 (20/2). We discuss whether different interaction patterns reflect different phage lifestyles or whether they may be artifacts of sampling. Phages that infect the same host can interact with different host target proteins, as exemplified by E. coli phage λ and T7. Despite decades of intensive investigation, only a fraction of these phage interactomes are known. Technical limitations and a lack of depth in many studies explain the gaps in our knowledge. Strategies to complete current interactome maps are described. Although limited space precludes detailed overviews of phage molecular biology, this compilation will allow future studies to put interaction data into the context of phage biology. PMID:22748812

  7. Recombinant protein production technology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recombinant protein production is an important technology for antibody production, biochemical activity study, and structural determination during the post-genomic era. Limiting factors in recombinant protein production include low-level protein expression, protein precipitation, and loss of protein...

  8. Actin-based propulsion of functionalized hard versus fluid spherical objects

    NASA Astrophysics Data System (ADS)

    Delatour, Vincent; Shekhar, Shashank; Reymann, Anne-Cécile; Didry, Dominique; Diêp Lê, Kim Hô; Romet-Lemonne, Guillaume; Helfer, Emmanuèle; Carlier, Marie-France

    2008-02-01

    The directed polymerization of a branched actin network against a functionalized surface drives cell protrusions and organelle propulsion in living cells. Solid microspheres or giant unilamellar vesicles, functionalized with neural Wiskott Aldrich syndrome protein (N-WASP), initiate the formation of a branched actin array using actin-related protein 2/3 (Arp2/3) complex, when placed in a motility assay reconstituted with pure proteins. These systems are useful biomimetic models of actin-based propulsion that allow to address how the interplay between the physical properties of the functionalized surface and the dynamics of the actin cytoskeleton determines motile behavior. Both solid beads and deformable vesicles display either continuous or saltatory propulsive motions, which are analyzed comparatively; we show that the deformability of liposomes and the mobility of N-WASP at the lipid surface affect the dynamic and structural parameters of the actin meshwork. Our results indicate that beads and vesicles use different mechanisms to translate insertional polymerization of actin at their surface into directed movement: stress relaxation within the actin gel prevents the accumulation of filaments at the front of moving beads, while segregation of nucleators reduces actin polymerization at the front of moving vesicles.

  9. Protein inference: A protein quantification perspective.

    PubMed

    He, Zengyou; Huang, Ting; Liu, Xiaoqing; Zhu, Peijun; Teng, Ben; Deng, Shengchun

    2016-08-01

    In mass spectrometry-based shotgun proteomics, protein quantification and protein identification are two major computational problems. To quantify the protein abundance, a list of proteins must be firstly inferred from the raw data. Then the relative or absolute protein abundance is estimated with quantification methods, such as spectral counting. Until now, most researchers have been dealing with these two processes separately. In fact, the protein inference problem can be regarded as a special protein quantification problem in the sense that truly present proteins are those proteins whose abundance values are not zero. Some recent published papers have conceptually discussed this possibility. However, there is still a lack of rigorous experimental studies to test this hypothesis. In this paper, we investigate the feasibility of using protein quantification methods to solve the protein inference problem. Protein inference methods aim to determine whether each candidate protein is present in the sample or not. Protein quantification methods estimate the abundance value of each inferred protein. Naturally, the abundance value of an absent protein should be zero. Thus, we argue that the protein inference problem can be viewed as a special protein quantification problem in which one protein is considered to be present if its abundance is not zero. Based on this idea, our paper tries to use three simple protein quantification methods to solve the protein inference problem effectively. The experimental results on six data sets show that these three methods are competitive with previous protein inference algorithms. This demonstrates that it is plausible to model the protein inference problem as a special protein quantification task, which opens the door of devising more effective protein inference algorithms from a quantification perspective. The source codes of our methods are available at: http://code.google.com/p/protein-inference/. PMID:26935399

  10. Inhibition of the Expression of the Small Heat Shock Protein αB-Crystallin Inhibits Exosome Secretion in Human Retinal Pigment Epithelial Cells in Culture.

    PubMed

    Gangalum, Rajendra K; Bhat, Ankur M; Kohan, Sirus A; Bhat, Suraj P

    2016-06-17

    Exosomes carry cell type-specific molecular cargo to extracellular destinations and therefore act as lateral vectors of intercellular communication and transfer of genetic information from one cell to the other. We have shown previously that the small heat shock protein αB-crystallin (αB) is exported out of the adult human retinal pigment epithelial cells (ARPE19) packaged in exosomes. Here, we demonstrate that inhibition of the expression of αB via shRNA inhibits exosome secretion from ARPE19 cells indicating that exosomal cargo may have a role in exosome biogenesis (synthesis and/or secretion). Sucrose density gradient fractionation of the culture medium and cellular extracts suggests continued synthesis of exosomes but an inhibition of exosome secretion. In cells where αB expression was inhibited, the distribution of CD63 (LAMP3), an exosome marker, is markedly altered from the normal dispersed pattern to a stacked perinuclear presence. Interestingly, the total anti-CD63(LAMP3) immunofluorescence in the native and αB-inhibited cells remains unchanged suggesting continued exosome synthesis under conditions of impaired exosome secretion. Importantly, inhibition of the expression of αB results in a phenotype of the RPE cell that contains an increased number of vacuoles and enlarged (fused) vesicles that show increased presence of CD63(LAMP3) and LAMP1 indicating enhancement of the endolysosomal compartment. This is further corroborated by increased Rab7 labeling of this compartment (RabGTPase 7 is known to be associated with late endosome maturation). These data collectively point to a regulatory role for αB in exosome biogenesis possibly via its involvement at a branch point in the endocytic pathway that facilitates secretion of exosomes. PMID:27129211

  11. Mechanical force-induced polymerization and depolymerization of F-actin at water/solid interfaces.

    PubMed

    Zhang, Xueqiang; Hu, Xiuyuan; Lei, Haozhi; Hu, Jun; Zhang, Yi

    2016-03-21

    Actin molecules are among the three main cytoskeleton proteins of cells and undergo rapid cycling to regulate critical processes such as endocytosis, cytokinesis, cell polarity, and cell morphogenesis. Although extensive studies have been carried out on the dynamics as well as biological functions of actin polymerization and depolymerization both in vivo and in vitro, the molecular mechanisms by which cells sense and respond to mechanical signals are not fully understood. In particular, little attention has been paid to the effect of a physical force that is exerted directly on the actin cytoskeleton. In this paper, we have explored how the mechanical force affects the actin polymerization and depolymerization behaviors at water/solid interfaces using an atomic force microscope (AFM) operated in liquid. By raster scanning an AFM probe on a substrate surface with a certain load, it was found that actin monomers could polymerize into filaments without the help of actin related proteins (ARPs). Further study indicated that actin monomers were inclined to form filaments only under a small scanning load. The polymerized actin filaments would be depolymerized when the mechanical force was stronger. A possible mechanism has been suggested to explain the mechanical force induced actin polymerization. PMID:26928199

  12. Multiple modes of regulation of the human Ino80 SNF2 ATPase by subunits of the INO80 chromatin-remodeling complex

    PubMed Central

    Chen, Lu; Conaway, Ronald C.; Conaway, Joan W.

    2013-01-01

    SNF2 family ATPases are ATP-dependent motors that often function in multisubunit complexes to regulate chromatin structure. Although the central role of SNF2 ATPases in chromatin biology is well established, mechanisms by which their catalytic activities are regulated by additional subunits of chromatin-remodeling complexes are less well understood. Here we present evidence that the human Inositol auxotrophy 80 (Ino80) SNF2 ATPase is subject to regulation at multiple levels in the INO80 chromatin-remodeling complex. The zinc finger histidine triad domain-containing protein Ies2 (Ino Eighty Subunit 2) functions as a potent activator of the intrinsic catalytic activity of the Ino80 ATPase, whereas the YL-1 family Ies6 (Ino Eighty Subunit 6) and actin-related Arp5 proteins function together to promote binding of the Ino80 ATPase to nucleosomes. These findings support the idea that both substrate recognition and the intrinsic catalytic activities of SNF2 ATPases have evolved as important sites for their regulation. PMID:24297934

  13. VASP Governs Actin Dynamics by Modulating Filament Anchoring

    PubMed Central

    Trichet, Léa; Campàs, Otger; Sykes, Cécile; Plastino, Julie

    2007-01-01

    Actin filament dynamics at the cell membrane are important for cell-matrix and cell-cell adhesions and the protrusion of the leading edge. Since actin filaments must be connected to the cell membrane to exert forces but must also detach from the membrane to allow it to move and evolve, the balance between actin filament tethering and detachment at adhesion sites and the leading edge is key for cell shape changes and motility. How this fine tuning is performed in cells remains an open question, but possible candidates are the Drosophila enabled/vasodilator-stimulated phosphoprotein (Ena/VASP) family of proteins, which localize to dynamic actin structures in the cell. Here we study VASP-mediated actin-related proteins 2/3 (Arp2/3) complex-dependent actin dynamics using a substrate that mimics the fluid properties of the cell membrane: an oil-water interface. We show evidence that polymerization activators undergo diffusion and convection on the fluid surface, due to continual attachment and detachment to the actin network. These dynamics are enhanced in the presence of VASP, and we observe cycles of catastrophic detachment of the actin network from the surface, resulting in stop-and-go motion. These results point to a role for VASP in the modulation of filament anchoring, with implications for actin dynamics at cell adhesions and at the leading edge of the cell. PMID:17098798

  14. Interfacing protein lysine acetylation and protein phosphorylation

    PubMed Central

    Tran, Hue T.; Uhrig, R. Glen; Nimick, Mhairi; Moorhead, Greg B.

    2012-01-01

    Recognition that different protein covalent modifications can operate in concert to regulate a single protein has forced us to re-think the relationship between amino acid side chain modifications and protein function. Results presented by Tran et al. 2012 demonstrate the association of a protein phosphatase (PP2A) with a histone/lysine deacetylase (HDA14) on plant microtubules along with a histone/lysine acetyltransferase (ELP3). This finding reveals a regulatory interface between two prevalent covalent protein modifications, protein phosphorylation and acetylation, emphasizing the integrated complexity of post-translational protein regulation found in nature. PMID:22827947

  15. How capping protein enhances actin filament growth and nucleation on biomimetic beads

    NASA Astrophysics Data System (ADS)

    Wang, Ruizhe; Carlsson, Anders E.

    2015-12-01

    Capping protein (CP), which caps the growing ends of actin filaments, accelerates actin-based motility. Recent experiments on biomimetic beads have shown that CP also enhances the rate of actin filament nucleation. Proposed explanations for these phenomena include (i) the actin funneling hypothesis (AFH), in which the presence of CP increases the free-actin concentration, and (ii) the monomer gating model, in which CP binding to actin filament barbed ends makes more monomers available for filament nucleation. To establish how CP increases the rates of filament elongation and nucleation on biomimetic beads, we perform a quantitative modeling analysis of actin polymerization, using rate equations that include actin filament nucleation, polymerization and capping, as modified by monomer depletion near the surface of the bead. With one adjustable parameter, our simulation results match previously measured time courses of polymerized actin and filament number. The results support a version of the AFH where CP increases the local actin monomer concentration at the bead surface, but leaves the global free-actin concentration nearly constant. Because the rate of filament nucleation increases with the monomer concentration, the increased local monomer concentration enhances actin filament nucleation. We derive a closed-form formula for the characteristic CP concentration where the local free-actin concentration reaches half the bulk value, and find it to be comparable to the global Arp2/3 complex concentration. We also propose an experimental protocol for distinguishing branching nucleation of filaments from spontaneous nucleation.

  16. Treatment of proteins with dietary polyphenols lowers the formation of AGEs and AGE-induced toxicity.

    PubMed

    Zhang, Xinchen; Hu, Shuting; Chen, Feng; Wang, Mingfu

    2014-10-01

    Advanced glycation endproducts (AGEs) are a group of harmful compounds produced either endogenously or during thermal food processing. Once absorbed by humans via food intake, AGEs can cause oxidative cell damage and contribute to pathological development of various diseases. The AGE-inhibitory activity of dietary polyphenols in vitro has been extensively reported before, but the current study is pioneering in examining the antiglycation activity of five selected dietary polyphenols (phloretin, naringenin, epicatechin, chlorogenic acid, and rosmarinic acid) during the thermal protein glycation process. When added into the glucose-casein glycation model heated at 120 °C for 2 h, these polyphenols were capable of inhibiting the formation of both total fluorescent AGEs and nonfluorescent carboxymethyllysine (CML). The thermal stability and transformation of polyphenols are likely important factors affecting their antioxidant activity and inhibitory efficacy of reactive carbonyl species formation. Treatment with epicatechin would lower not only AGE formation but also AGE-induced cytotoxicity and oxidative stress to human retinal pigment epithelial (ARPE-19) cells. PMID:25208810

  17. Length, protein protein interactions, and complexity

    NASA Astrophysics Data System (ADS)

    Tan, Taison; Frenkel, Daan; Gupta, Vishal; Deem, Michael W.

    2005-05-01

    The evolutionary reason for the increase in gene length from archaea to prokaryotes to eukaryotes observed in large-scale genome sequencing efforts has been unclear. We propose here that the increasing complexity of protein-protein interactions has driven the selection of longer proteins, as they are more able to distinguish among a larger number of distinct interactions due to their greater average surface area. Annotated protein sequences available from the SWISS-PROT database were analyzed for 13 eukaryotes, eight bacteria, and two archaea species. The number of subcellular locations to which each protein is associated is used as a measure of the number of interactions to which a protein participates. Two databases of yeast protein-protein interactions were used as another measure of the number of interactions to which each S. cerevisiae protein participates. Protein length is shown to correlate with both number of subcellular locations to which a protein is associated and number of interactions as measured by yeast two-hybrid experiments. Protein length is also shown to correlate with the probability that the protein is encoded by an essential gene. Interestingly, average protein length and number of subcellular locations are not significantly different between all human proteins and protein targets of known, marketed drugs. Increased protein length appears to be a significant mechanism by which the increasing complexity of protein-protein interaction networks is accommodated within the natural evolution of species. Consideration of protein length may be a valuable tool in drug design, one that predicts different strategies for inhibiting interactions in aberrant and normal pathways.

  18. The IQGAP1 Protein Is a Calmodulin-regulated Barbed End Capper of Actin Filaments

    PubMed Central

    Pelikan-Conchaudron, Andrea; Le Clainche, Christophe; Didry, Dominique; Carlier, Marie-France

    2011-01-01

    IQGAP1 is a large modular protein that displays multiple partnership and is thought to act as a scaffold in coupling cell signaling to the actin and microtubule cytoskeletons in cell migration, adhesion, and cytokinesis. However the molecular mechanisms underlying the activities of IQGAP1 are poorly understood in part because of its large size, poor solubility and lack of functional assays to challenge biochemical properties in various contexts. We have purified bacterially expressed recombinant human IQGAP1. The protein binds Cdc42, Rac1, and the CRIB domain of N-WASP in a calmodulin-sensitive fashion. We further show that in addition to bundling of filaments via a single N-terminal calponin-homology domain, IQGAP1 actually regulates actin assembly. It caps barbed ends, with a higher affinity for ADP-bound terminal subunits (KB = 4 nm). The barbed end capping activity is inhibited by calmodulin, consistent with calmodulin binding to IQGAP1 with a KC of 40 nm, both in the absence and presence of Ca2+ ions. The barbed end capping activity resides in the C-terminal half of IQGAP1. It is possible that the capping activity of IQGAP1 accounts for its stimulation of cell migration. We further find that bacterially expressed recombinant IQGAP1 fragments easily co-purify with nucleic acids that turn out to activate N-WASP protein to branch filaments with Arp2/3 complex. The present results open perspectives for tackling the function of IQGAP1 in more complex reconstituted systems. PMID:21730051

  19. EDITORIAL: Precision proteins Precision proteins

    NASA Astrophysics Data System (ADS)

    Demming, Anna

    2010-06-01

    Since the birth of modern day medicine, during the times of Hippocrates in ancient Greece, the profession has developed from the rudimentary classification of disease into a rigorous science with an inspiring capability to treat and cure. Scientific methodology has distilled clinical diagnostic tools from the early arts of prognosis, which used to rely as much on revelation and prophecy, as intuition and judgement [1]. Over the past decade, research into the interactions between proteins and nanosystems has provided some ingenious and apt techniques for delving into the intricacies of anatomical systems. In vivo biosensing has emerged as a vibrant field of research, as much of medical diagnosis relies on the detection of substances or an imbalance in the chemicals in the body. The inherent properties of nanoscale structures, such as cantilevers, make them well suited to biosensing applications that demand the detection of molecules at very low concentrations. Measurable deflections in cantilevers functionalised with antibodies provide quantitative indicators of the presence of specific antigens when the two react. Such developments have roused mounting interest in the interactions of proteins with nanostructures, such as carbon nanotubes [3], which have demonstrated great potential as generic biomarkers. Plasmonic properties are also being exploited in sensing applications, such as the molecular sentinel recently devised by researchers in the US. The device uses the plasmonic properties of a silver nanoparticle linked to a Raman labelled hairpin DNA probe to signal changes in the probe geometry resulting from interactions with substances in the environment. Success stories so far include the detection of two specific genes associated with breast cancer [4]. A greater understanding of how RNA interference regulates gene expression has highlighted the potential of using this natural process as another agent for combating disease in personalized medicine. However, the

  20. EDITORIAL: Precision proteins Precision proteins

    NASA Astrophysics Data System (ADS)

    Demming, Anna

    2010-06-01

    Since the birth of modern day medicine, during the times of Hippocrates in ancient Greece, the profession has developed from the rudimentary classification of disease into a rigorous science with an inspiring capability to treat and cure. Scientific methodology has distilled clinical diagnostic tools from the early arts of prognosis, which used to rely as much on revelation and prophecy, as intuition and judgement [1]. Over the past decade, research into the interactions between proteins and nanosystems has provided some ingenious and apt techniques for delving into the intricacies of anatomical systems. In vivo biosensing has emerged as a vibrant field of research, as much of medical diagnosis relies on the detection of substances or an imbalance in the chemicals in the body. The inherent properties of nanoscale structures, such as cantilevers, make them well suited to biosensing applications that demand the detection of molecules at very low concentrations. Measurable deflections in cantilevers functionalised with antibodies provide quantitative indicators of the presence of specific antigens when the two react. Such developments have roused mounting interest in the interactions of proteins with nanostructures, such as carbon nanotubes [3], which have demonstrated great potential as generic biomarkers. Plasmonic properties are also being exploited in sensing applications, such as the molecular sentinel recently devised by researchers in the US. The device uses the plasmonic properties of a silver nanoparticle linked to a Raman labelled hairpin DNA probe to signal changes in the probe geometry resulting from interactions with substances in the environment. Success stories so far include the detection of two specific genes associated with breast cancer [4]. A greater understanding of how RNA interference regulates gene expression has highlighted the potential of using this natural process as another agent for combating disease in personalized medicine. However, the

  1. Tonicity-responsive enhancer binding protein regulates the expression of aldose reductase and protein kinase C δ in a mouse model of diabetic retinopathy.

    PubMed

    Park, Jeongsook; Kim, Hwajin; Park, So Yun; Lim, Sun Woo; Kim, Yoon Sook; Lee, Dong Hoon; Roh, Gu Seob; Kim, Hyun Joon; Kang, Sang Soo; Cho, Gyeong Jae; Jeong, Bo-Young; Kwon, H Moo; Choi, Wan Sung

    2014-05-01

    Recent studies revealed that Tonicity-responsive enhancer binding protein (TonEBP) directly regulates the transcription of aldose reductase (AR), which catalyzes the first step of the polyol pathway of glucose metabolism. Activation of protein kinase C δ (PKCδ) is dependent on AR and it has been linked to diabetic complications. However, whether TonEBP affects expressions of AR and PKCδ in diabetic retinopathy was not clearly shown. In this study, we used TonEBP heterozygote mice to study the role of TonEBP in streptozotocin (STZ)-induced diabetic retinopathy. We performed immunofluorescence staining and found that retinal expressions of AR and PKCδ were significantly reduced in the heterozygotes compared to wild type littermates, particularly in ganglion cell layer. To examine further the effect of TonEBP reduction in retinal tissues, we performed intravitreal injection of TonEBP siRNA and confirmed the decrease in AR and PKCδ levels. In addition, we found that a proapoptotic factor, Bax level was reduced and a survival factor, Bcl2 level was increased after injection of TonEBP siRNA, indicating that TonEBP mediates apoptotic cell death. In parallel, TonEBP siRNA was applied to the in vitro human retinal pigment epithelial (ARPE-19) cells cultured in high glucose media. We have consistently found the decrease in AR and PKCδ levels and changes in apoptotic factors for survival. Together, these results clearly demonstrated that hyperglycemia-induced TonEBP plays a crucial role in increasing AR and PKCδ levels and leading to apoptotic death. Our findings suggest that TonEBP reduction is an effective therapeutic strategy for diabetic retinopathy. PMID:24631337

  2. Shotgun protein sequencing.

    SciTech Connect

    Faulon, Jean-Loup Michel; Heffelfinger, Grant S.

    2009-06-01

    A novel experimental and computational technique based on multiple enzymatic digestion of a protein or protein mixture that reconstructs protein sequences from sequences of overlapping peptides is described in this SAND report. This approach, analogous to shotgun sequencing of DNA, is to be used to sequence alternative spliced proteins, to identify post-translational modifications, and to sequence genetically engineered proteins.

  3. Protein Crystal Based Nanomaterials

    NASA Technical Reports Server (NTRS)

    Bell, Jeffrey A.; VanRoey, Patrick

    2001-01-01

    This is the final report on a NASA Grant. It concerns a description of work done, which includes: (1) Protein crystals cross-linked to form fibers; (2) Engineering of protein to favor crystallization; (3) Better knowledge-based potentials for protein-protein contacts; (4) Simulation of protein crystallization.

  4. Protein folding, protein homeostasis, and cancer

    PubMed Central

    Van Drie, John H.

    2011-01-01

    Proteins fold into their functional 3-dimensional structures from a linear amino acid sequence. In vitro this process is spontaneous; while in vivo it is orchestrated by a specialized set of proteins, called chaperones. Protein folding is an ongoing cellular process, as cellular proteins constantly undergo synthesis and degradation. Here emerging links between this process and cancer are reviewed. This perspective both yields insights into the current struggle to develop novel cancer chemotherapeutics and has implications for future chemotherapy discovery. PMID:21272445

  5. Split-Protein Systems: Beyond Binary Protein-Protein Interactions

    PubMed Central

    Shekhawat, Sujan S.; Ghosh, Indraneel

    2011-01-01

    It has been estimated that 650,000 protein-protein interactions exist in the human interactome [1], a subset of all possible macromolecular partnerships that dictate life. Thus there is a continued need for the development of sensitive and user-friendly methods for cataloguing biomacromolecules in complex environments and for detecting their interactions, modifications, and cellular location. Such methods also allow for establishing differences in the interactome between a normal and diseased cellular state and for quantifying the outcome of therapeutic intervention. A promising approach for deconvoluting the role of macromolecular partnerships is split-protein reassembly, also called protein fragment complementation. This approach relies on the appropriate fragmentation of protein reporters, such as the green fluorescent protein or firefly luciferase, which when attached to possible interacting partners can reassemble and regain function, thereby confirming the partnership. Split-protein methods have been effectively utilized for detecting protein-protein interactions in cell-free systems, E. coli, yeast, mammalian cells, plants, and live animals. Herein, we present recent advances in engineering split-protein systems that allow for the rapid detection of ternary protein complexes, small molecule inhibitors, as well as a variety of macromolecules including nucleic acids, poly(ADP) ribose, and iron sulfur clusters. We also present advances that combine split-protein systems with chemical inducers of dimerization strategies that allow for regulating the activity of orthogonal split-proteases as well as aid in identifying enzyme inhibitors. Finally, we discuss autoinhibition strategies leading to turn-on sensors as well as future directions in split-protein methodology including possible therapeutic approaches. PMID:22070901

  6. Split-protein systems: beyond binary protein-protein interactions.

    PubMed

    Shekhawat, Sujan S; Ghosh, Indraneel

    2011-12-01

    It has been estimated that 650,000 protein-protein interactions exist in the human interactome (Stumpf et al., 2008), a subset of all possible macromolecular partnerships that dictate life. Thus there is a continued need for the development of sensitive and user-friendly methods for cataloguing biomacromolecules in complex environments and for detecting their interactions, modifications, and cellular location. Such methods also allow for establishing differences in the interactome between a normal and diseased cellular state and for quantifying the outcome of therapeutic intervention. A promising approach for deconvoluting the role of macromolecular partnerships is split-protein reassembly, also called protein fragment complementation. This approach relies on the appropriate fragmentation of protein reporters, such as the green fluorescent protein or firefly luciferase, which when attached to possible interacting partners can reassemble and regain function, thereby confirming the partnership. Split-protein methods have been effectively utilized for detecting protein-protein interactions in cell-free systems, Escherichia coli, yeast, mammalian cells, plants, and live animals. Herein, we present recent advances in engineering split-protein systems that allow for the rapid detection of ternary protein complexes, small molecule inhibitors, as well as a variety of macromolecules including nucleic acids, poly(ADP) ribose, and iron sulfur clusters. We also present advances that combine split-protein systems with chemical inducers of dimerization strategies that allow for regulating the activity of orthogonal split-proteases as well as aid in identifying enzyme inhibitors. Finally, we discuss autoinhibition strategies leading to turn-on sensors as well as future directions in split-protein methodology including possible therapeutic approaches. PMID:22070901

  7. Protein in diet

    MedlinePlus

    ... basic structure of protein is a chain of amino acids. You need protein in your diet to help ... Protein foods are broken down into parts called amino acids during digestion. The human body needs a number ...

  8. Protein-losing enteropathy

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/007338.htm Protein-losing enteropathy To use the sharing features on this page, please enable JavaScript. Protein-losing enteropathy is an abnormal loss of protein ...

  9. Protein electrophoresis - serum

    MedlinePlus

    ... digestive tract to absorb proteins ( protein-losing enteropathy ) Malnutrition Kidney disorder called nephrotic syndrome Scarring of the ... may indicate: Abnormally low level of LDL cholesterol Malnutrition Increased gamma globulin proteins may indicate: Bone marrow ...

  10. Pushing with actin: from cells to pathogens.

    PubMed

    Small, J Victor

    2015-02-01

    Actin polymerization is harnessed by cells to generate lamellipodia for movement and by a subclass of pathogens to facilitate invasion of their infected hosts. Using electron tomography (ET), we have shown that lamellipodia are formed via the generation of subsets of actin filaments joined by branch junctions. Image averaging produced a 2.9 nm resolution model of branch junctions in situ and revealed a close fit to the electron density map of the actin-related protein 2/3 (Arp2/3)-actin complex in vitro. Correlated live-cell imaging and ET was also used to determine how actin networks are created and remodelled during the initiation and inhibition of protrusion in lamellipodia. Listeria, Rickettsia and viruses, such as vaccinia virus and baculovirus, exploit the actin machinery of host cells to generate propulsive actin comet tails to disseminate their infection. By applying ET, we have shown that baculovirus generates at its rear a fishbone-like array of subsets of branched actin filaments, with an average of only four filaments engaged in pushing at any one time. In both of these studies, the application of ET of negatively stained cytoskeletons for higher filament resolution and cryo-ET for preserving overall 3D morphology was crucial for obtaining a complete structure-function analysis of actin-driven propulsion. PMID:25619250

  11. Signal strength regulates antigen-mediated T-cell deceleration by distinct mechanisms to promote local exploration or arrest

    PubMed Central

    Moreau, Hélène D.; Lemaître, Fabrice; Garrod, Kym R.; Garcia, Zacarias; Lennon-Duménil, Ana-Maria; Bousso, Philippe

    2015-01-01

    T lymphocytes are highly motile cells that decelerate upon antigen recognition. These cells can either completely stop or maintain a low level of motility, forming contacts referred to as synapses or kinapses, respectively. Whether similar or distinct molecular mechanisms regulate T-cell deceleration during synapses or kinapses is unclear. Here, we used microfabricated channels and intravital imaging to observe and manipulate T-cell kinapses and synapses. We report that high-affinity antigen induced a pronounced deceleration selectively dependent on Ca2+ signals and actin-related protein 2/3 complex (Arp2/3) activity. In contrast, low-affinity antigens induced a switch of migration mode that promotes T-cell exploratory behavior, characterized by partial deceleration and frequent direction changes. This switch depended on T-cell receptor binding but was largely independent of downstream signaling. We propose that distinct mechanisms of T-cell deceleration can be triggered during antigenic recognition to favor local exploration and signal integration upon suboptimal stimulus and complete arrest on the best antigen-presenting cells. PMID:26371316

  12. Domains mediate protein-protein interactions and nucleate protein assemblies.

    PubMed

    Costa, S; Cesareni, G

    2008-01-01

    Cell physiology is governed by an intricate mesh of physical and functional links among proteins, nucleic acids and other metabolites. The recent information flood coming from large-scale genomic and proteomic approaches allows us to foresee the possibility of compiling an exhaustive list of the molecules present within a cell, enriched with quantitative information on concentration and cellular localization. Moreover, several high-throughput experimental and computational techniques have been devised to map all the protein interactions occurring in a living cell. So far, such maps have been drawn as graphs where nodes represent proteins and edges represent interactions. However, this representation does not take into account the intrinsically modular nature of proteins and thus fails in providing an effective description of the determinants of binding. Since proteins are composed of domains that often confer on proteins their binding capabilities, a more informative description of the interaction network would detail, for each pair of interacting proteins in the network, which domains mediate the binding. Understanding how protein domains combine to mediate protein interactions would allow one to add important features to the protein interaction network, making it possible to discriminate between simultaneously occurring and mutually exclusive interactions. This objective can be achieved by experimentally characterizing domain recognition specificity or by analyzing the frequency of co-occurring domains in proteins that do interact. Such approaches allow gaining insights on the topology of complexes with unknown three-dimensional structure, thus opening the prospect of adopting a more rational strategy in developing drugs designed to selectively target specific protein interactions. PMID:18491061

  13. Drugging Membrane Protein Interactions.

    PubMed

    Yin, Hang; Flynn, Aaron D

    2016-07-11

    The majority of therapeutics target membrane proteins, accessible on the surface of cells, to alter cellular signaling. Cells use membrane proteins to transduce signals into cells, transport ions and molecules, bind cells to a surface or substrate, and catalyze reactions. Newly devised technologies allow us to drug conventionally "undruggable" regions of membrane proteins, enabling modulation of protein-protein, protein-lipid, and protein-nucleic acid interactions. In this review, we survey the state of the art of high-throughput screening and rational design in drug discovery, and we evaluate the advances in biological understanding and technological capacity that will drive pharmacotherapy forward against unorthodox membrane protein targets. PMID:26863923

  14. Protein sensing with engineered protein nanopores*

    PubMed Central

    Mohammad, Mohammad M.; Movileanu, Liviu

    2013-01-01

    The use of nanopores is a powerful new frontier in single-molecule sciences. Nanopores have been used effectively in exploring various biophysical features of small polypeptides and proteins, such as their folding state and structure, ligand interactions, and enzymatic activity. In particular, the α-hemolysin protein pore (αHL) has been used extensively for the detection, characterization and analysis of polypeptides, because this protein nanopore is highly robust, versatile and tractable under various experimental conditions. Inspired by the mechanisms of protein translocation across the outer membrane translocases of mitochondria, we have shown the ability to use nanopore-probe techniques in controlling a single protein using engineered αHL pores. Here, we provide a detailed protocol for the preparation of αHL protein nanopores. Moreover, we demonstrate that placing attractive electrostatic traps is instrumental in tackling single-molecule stochastic sensing of folded proteins. PMID:22528256

  15. Cdc42 Interacting Protein 4 promotes breast cancer cell invasion and formation of invadopodia through activation of N-WASp

    PubMed Central

    Pichot, Christina S.; Arvanitis, Constadina; Hartig, Sean M.; Jensen, Samuel A.; Bechill, John; Marzouk, Saad; Yu, Jindan; Frost, Jeffrey A.; Corey, Seth J.

    2010-01-01

    In the earliest stages of metastasis, breast cancer cells must reorganize the cytoskeleton to affect cell shape change and promote cell invasion and motility. These events require the cytoskeletal regulators Cdc42 and Rho, their effectors, such as N-WASp/WAVE, and direct inducers of actin polymerization such as Arp2/3. Little consideration has been given to molecules that shape the cell membrane. The F-BAR proteins CIP4, TOCA-1, and FBP17 generate membrane curvature and act as scaffolding proteins for activated Cdc42 and N-WASp. We found that expression of CIP4, but not TOCA-1 or FBP17, was increased in invasive breast cancer cell lines in comparison to weakly or non-invasive breast cancer cell lines. Endogenous CIP4 localized to the leading edge of migrating cells and to invadopodia in cells invading gelatin. Because CIP4 serves as a scaffolding protein for Cdc42, Src, and N-WASp, we tested whether loss of CIP4 could result in decreased N-WASp function. Interaction between CIP4 and N-WASp was EGF-responsive, and CIP4 silencing by siRNA caused decreased tyrosine phosphorylation of N-WASp at a Src-dependent activation site (Y256). CIP4 silencing also impaired the migration and invasion of MDA-MB-231 cells and was associated with decreased formation of invadopodia and gelatin degradation. This study presents a new role for CIP4 in the promotion of migration and invasion of MDA-MB-231 breast cancer cells and establishes the contribution of F-BAR proteins to cancer cell motility and invasion. PMID:20940394

  16. Nanotechnologies in protein microarrays.

    PubMed

    Krizkova, Sona; Heger, Zbynek; Zalewska, Marta; Moulick, Amitava; Adam, Vojtech; Kizek, Rene

    2015-01-01

    Protein microarray technology became an important research tool for study and detection of proteins, protein-protein interactions and a number of other applications. The utilization of nanoparticle-based materials and nanotechnology-based techniques for immobilization allows us not only to extend the surface for biomolecule immobilization resulting in enhanced substrate binding properties, decreased background signals and enhanced reporter systems for more sensitive assays. Generally in contemporarily developed microarray systems, multiple nanotechnology-based techniques are combined. In this review, applications of nanoparticles and nanotechnologies in creating protein microarrays, proteins immobilization and detection are summarized. We anticipate that advanced nanotechnologies can be exploited to expand promising fields of proteins identification, monitoring of protein-protein or drug-protein interactions, or proteins structures. PMID:26039143

  17. PREFACE: Protein protein interactions: principles and predictions

    NASA Astrophysics Data System (ADS)

    Nussinov, Ruth; Tsai, Chung-Jung

    2005-06-01

    Proteins are the `workhorses' of the cell. Their roles span functions as diverse as being molecular machines and signalling. They carry out catalytic reactions, transport, form viral capsids, traverse membranes and form regulated channels, transmit information from DNA to RNA, making possible the synthesis of new proteins, and they are responsible for the degradation of unnecessary proteins and nucleic acids. They are the vehicles of the immune response and are responsible for viral entry into the cell. Given their importance, considerable effort has been centered on the prediction of protein function. A prime way to do this is through identification of binding partners. If the function of at least one of the components with which the protein interacts is known, that should let us assign its function(s) and the pathway(s) in which it plays a role. This holds since the vast majority of their chores in the living cell involve protein-protein interactions. Hence, through the intricate network of these interactions we can map cellular pathways, their interconnectivities and their dynamic regulation. Their identification is at the heart of functional genomics; their prediction is crucial for drug discovery. Knowledge of the pathway, its topology, length, and dynamics may provide useful information for forecasting side effects. The goal of predicting protein-protein interactions is daunting. Some associations are obligatory, others are continuously forming and dissociating. In principle, from the physical standpoint, any two proteins can interact, but under what conditions and at which strength? The principles of protein-protein interactions are general: the non-covalent interactions of two proteins are largely the outcome of the hydrophobic effect, which drives the interactions. In addition, hydrogen bonds and electrostatic interactions play important roles. Thus, many of the interactions observed in vitro are the outcome of experimental overexpression. Protein disorder

  18. Protein sequence comparison and protein evolution

    SciTech Connect

    Pearson, W.R.

    1995-12-31

    This tutorial was one of eight tutorials selected to be presented at the Third International Conference on Intelligent Systems for Molecular Biology which was held in the United Kingdom from July 16 to 19, 1995. This tutorial examines how the information conserved during the evolution of a protein molecule can be used to infer reliably homology, and thus a shared proteinfold and possibly a shared active site or function. The authors start by reviewing a geological/evolutionary time scale. Next they look at the evolution of several protein families. During the tutorial, these families will be used to demonstrate that homologous protein ancestry can be inferred with confidence. They also examine different modes of protein evolution and consider some hypotheses that have been presented to explain the very earliest events in protein evolution. The next part of the tutorial will examine the technical aspects of protein sequence comparison. Both optimal and heuristic algorithms and their associated parameters that are used to characterize protein sequence similarities are discussed. Perhaps more importantly, they survey the statistics of local similarity scores, and how these statistics can both be used to improve the selectivity of a search and to evaluate the significance of a match. They them examine distantly related members of three protein families, the serine proteases, the glutathione transferases, and the G-protein-coupled receptors (GCRs). Finally, the discuss how sequence similarity can be used to examine internal repeated or mosaic structures in proteins.

  19. Localization and role of MYO-1, an endocytic protein in hyphae of Neurospora crassa.

    PubMed

    Lara-Rojas, Fernando; Bartnicki-García, Salomón; Mouriño-Pérez, Rosa R

    2016-03-01

    The subapical endocytic collar is a prominent feature of hyphae of Neurospora crassa. It comprises a dynamic collection of actin patches associated with a number of proteins required for endocytosis, namely, ARP-2/3 complex, fimbrin, coronin, etc. We presently show that MYO-1 is another key component of this endocytic collar. A myo-1 sequence was identified in the genome of N. crassa and used it to generate a strain with a myo-1-sgfp allele under the ccg1 promoter. Examination of living hyphae by confocal microscopy, revealed MYO-1-GFP located mainly as a dynamic collection of small patches arranged in collar-like fashion in the hyphal subapex. Dual tagging showed MYO-1-GFP partially colocalized with two other endocytic proteins, fimbrin and coronin. MYO-1 was also present during septum formation. By recovering a viable strain, albeit severely inhibited, after deletion of myo-1, it was possible to investigate the phenotypic consequences of the elimination of MYO-1. Deletion of myo-1 caused a severe reduction in growth rate (95%), near absence of aerial mycelium and no conidiation. A reduced uptake of the lipophilic dye FM4-64 indicated a deficiency in endocytosis in the Δmyo-1 mutant. Hyphae were produced by the Δmyo-1 mutant but their morphogenesis was severely affected; hyphal morphology was distorted displaying irregular periods of isotropic and polarized growth. The morphological alterations were accompanied, and presumably caused, by a disruption in the organization and dynamics of a myosin-deprived actin cytoskeleton that, ultimately, compromised the stability and function of the Spitzenkörper as a vesicle supply center. PMID:26805950

  20. Genetic ablation of N-linked glycosylation reveals two key folding pathways for R345W fibulin-3, a secreted protein associated with retinal degeneration

    PubMed Central

    Hulleman, John D.; Kelly, Jeffery W.

    2015-01-01

    An R345W mutation in the N-glycoprotein, fibulin-3 (F3), results in inefficient F3 folding/secretion and higher intracellular F3 levels. Inheritance of this mutation causes the retinal dystrophy malattia leventinese. N-Linked glycosylation is a common cotranslational protein modification that can regulate protein folding efficiency and energetics. Therefore, we explored how N-glycosylation alters the protein homeostasis or proteostasis of wild-type (WT) and R345W F3 in ARPE-19 cells. Enzymatic and lectin binding assays confirmed that WT and R345W F3 are both primarily N-glycosylated at Asn249. Tunicamycin treatment selectively reduced R345W F3 secretion by 87% (vs. WT F3). Genetic elimination of F3 N-glycosylation (via an N249Q mutation) caused R345W F3 to aggregate intracellularly and adopt an altered secreted conformation. The endoplasmic reticulum (ER) chaperones GRP78 (glucose-regulated protein 78) and GRP94 (glucose-regulated protein 94), and the ER lectins calnexin and calreticulin were identified as F3 binding partners by immunoprecipitation. Significantly more N249Q and N249Q/R345W F3 interacted with GRP94, while substantially less N249Q and N249Q/R345W interacted with the ER lectins than their N-glycosylated counterparts. Inhibition of GRP94 ATPase activity reduced only N249Q/R345W F3 secretion (by 62%), demonstrating this variant’s unique reliance on GRP94 for secretion. These observations suggest that R345W F3, but not WT F3, requires N-glycosylation to acquire a stable, native-like structure.—Hulleman, J. D., Kelly, J. W. Genetic ablation of N-linked glycosylation reveals two key folding pathways for R345W fibulin-3, a secreted protein associated with retinal degeneration. PMID:25389134

  1. Sorghum and millet proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sorghum and millet proteins are an important source of dietary protein for significant numbers of people living throughout Africa and parts of Asia. Compared to other food proteins, such as those found in milk, eggs and wheat, little is known about the functionality of sorghum and millet proteins. ...

  2. Whey protein fractionation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Concentrated whey protein products from cheese whey, such as whey protein concentrate (WPC) and whey protein isolate (WPI), contain more than seven different types of proteins: alpha-lactalbumin (alpha-LA), beta-lactoglobulin (beta-LG), bovine serum albumin (BSA), immunoglobulins (Igs), lactoferrin ...

  3. Protein in diet

    MedlinePlus

    ... protein. The basic structure of protein is a chain of amino acids. You need protein in your diet to help your body repair cells and make new ones. Protein is also important for growth and development in children, teens, and pregnant women.

  4. Techniques in protein methylation.

    PubMed

    Lee, Jaeho; Cheng, Donghang; Bedford, Mark T

    2004-01-01

    Proteins can be methylated on the side-chain nitrogens of arginine and lysine residues or on carboxy-termini. Protein methylation is a way of subtly changing the primary sequence of a peptide so that it can encode more information. This common posttranslational modification is implicated in the regulation of a variety of processes including protein trafficking, transcription and protein-protein interactions. In this chapter, we will use the arginine methyltransferases to illustrate different approaches that have been developed to assess protein methylation. Both in vivo and in vitro methylation techniques are described, and the use of small molecule inhibitors of protein methylation will be demonstrated. PMID:15173617

  5. Biochemical Approaches for Discovering Protein-Protein Interactions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protein-protein interactions or protein complexes are indigenous to nearly all cellular processes, ranging from metabolism to structure. Elucidating both individual protein associations and complex protein interaction networks, while challenging, is an essential goal of functional genomics. For ex...

  6. Urine Protein and Urine Protein to Creatinine Ratio

    MedlinePlus

    ... limited. Home Visit Global Sites Search Help? Urine Protein and Urine Protein to Creatinine Ratio Share this page: Was this page helpful? Also known as: 24-Hour Urine Protein; Urine Total Protein; Urine Protein to Creatinine Ratio; ...

  7. [Protein expression and purification].

    PubMed

    Růčková, E; Müller, P; Vojtěšek, B

    2014-01-01

    Production of recombinant proteins is essential for many applications in both basic research and also in medicine, where recombinant proteins are used as pharmaceuticals. This review summarizes procedures involved in recombinant protein expression and purification, including molecular cloning of target genes into expression vectors, selection of the appropriate expression system, and protein purification techniques. Recombinant DNA technology allows protein engineering to modify protein stability, activity and function or to facilitate protein purification by affinity tag fusions. A wide range of cloning systems enabling fast and effective design of expression vectors is currently available. A first choice of protein expression system is usually the bacteria Escherichia coli. The main advantages of this prokaryotic expression system are low cost and simplicity; on the other hand this system is often unsuitable for production of complex mammalian proteins. Protein expression mediated by eukaryotic cells (yeast, insect and mammalian cells) usually produces properly folded and posttranslationally modified proteins. How-ever, cultivation of insect and, especially, mammalian cells is time consuming and expensive. Affinity tagged recombinant proteins are purified efficiently using affinity chromatography. An affinity tag is a protein or peptide that mediates specific binding to a chromatography column, unbound proteins are removed during a washing step and pure protein is subsequently eluted. PMID:24945544

  8. Protein- protein interaction detection system using fluorescent protein microdomains

    DOEpatents

    Waldo, Geoffrey S.; Cabantous, Stephanie

    2010-02-23

    The invention provides a protein labeling and interaction detection system based on engineered fragments of fluorescent and chromophoric proteins that require fused interacting polypeptides to drive the association of the fragments, and further are soluble and stable, and do not change the solubility of polypeptides to which they are fused. In one embodiment, a test protein X is fused to a sixteen amino acid fragment of GFP (.beta.-strand 10, amino acids 198-214), engineered to not perturb fusion protein solubility. A second test protein Y is fused to a sixteen amino acid fragment of GFP (.beta.-strand 11, amino acids 215-230), engineered to not perturb fusion protein solubility. When X and Y interact, they bring the GFP strands into proximity, and are detected by complementation with a third GFP fragment consisting of GFP amino acids 1-198 (strands 1-9). When GFP strands 10 and 11 are held together by interaction of protein X and Y, they spontaneous association with GFP strands 1-9, resulting in structural complementation, folding, and concomitant GFP fluorescence.

  9. Nck adaptors, besides promoting N-WASP mediated actin-nucleation activity at pedestals, influence the cellular levels of enteropathogenic Escherichia coli Tir effector.

    PubMed

    Nieto-Pelegrin, Elvira; Kenny, Brendan; Martinez-Quiles, Narcisa

    2014-01-01

    Enteropathogenic Escherichia coli (EPEC) binding to human intestinal cells triggers the formation of disease-associated actin rich structures called pedestals. The latter process requires the delivery, via a Type 3 secretion system, of the translocated Intimin receptor (Tir) protein into the host plasma membrane where binding of a host kinase-modified form to the bacterial surface protein Intimin triggers pedestal formation. Tir-Intimin interaction recruits the Nck adaptor to a Tir tyrosine phosphorylated residue where it activates neural Wiskott-Aldrich syndrome protein (N-WASP); initiating the major pathway to actin polymerization mediated by the actin-related protein (Arp) 2/3 complex. Previous studies with Nck-deficient mouse embryonic fibroblasts (MEFs) identified a key role for Nck in pedestal formation, presumed to reflect a lack of N-WASP activation. Here, we show the defect relates to reduced amounts of Tir within Nck-deficient cells. Indeed, Tir delivery and, thus, pedestal formation defects were much greater for MEFs than HeLa (human epithelial) cells. Crucially, the levels of two other effectors (EspB/EspF) within Nck-deficient MEFs were not reduced unlike that of Map (Mitochondrial associated protein) which, like Tir, requires CesT chaperone function for efficient delivery. Interestingly, drugs blocking various host protein degradation pathways failed to increase Tir cellular levels unlike an inhibitor of deacetylase activity (Trichostatin A; TSA). Treatments with TSA resulted in significant recovery of Tir levels, potentiation of actin polymerization and improvement in bacterial attachment to cells. Our findings have important implications for the current model of Tir-mediated actin polymerization and opens new lines of research in this area. PMID:25482634

  10. Association of anti-ribosomal P protein antibodies with neuropsychiatric and other manifestations of systemic lupus erythematosus.

    PubMed

    Abdel-Nasser, Ahmed M; Ghaleb, Rasha M; Mahmoud, Jehan A; Khairy, Wafaa; Mahmoud, Refaat M

    2008-11-01

    The objective of our study was to determine the prevalence of neuropsychiatric manifestations and anti-ribosomal P antibodies (aRP) in SLE and to examine the diagnostic utility and associations of aRP with neuropsychiatric and other disease manifestations. Thirty two consecutive SLE patients, diagnosed according to the updated 1997 ACR criteria, were studied. A full medical history, rheumatological, neurological, psychiatric examination, and psychometric evaluation, including a battery of tests for cognitive dysfunction and the Symptom Checklist-90-Revised depression and anxiety scales were administered to all patients. Disease activity was scored using the SLEDAI. Neuropsychiatric manifestations were diagnosed and categorized according to the 1999 ACR case definitions for 19 NPSLE syndromes. Laboratory and serologic tests including ANA, anti-ds DNA, anti-cardiolipin antibodies (aCL) and aRP (ELISA) were also carried out. Twenty six (81.2%) patients had one or more NP manifestations. Depression (59.4%), headache (46.9%) and cognitive dysfunction (37.5%) were the commonest NPSLE syndromes. Other less commonly detected manifestations included seizures, anxiety, acute confusional state, stroke, and psychosis. aRP was positive in seven (21.9%) patients, all of whom had one or more NPSLE syndromes. Patients with psychiatric manifestations in general and mood disorders in particular had significantly higher mean titers of aRP than patients without these disorders (p < 0.05). aRP were found to be significantly associated with a younger age at the onset of SLE, with more severe articular manifestations and with the presence but not the severity of depression. aRP were highly specific for NPSLE and depression, and they were highly sensitive for psychosis. Neuropsychiatric manifestations are found in 81.2% of unselected Egyptian SLE patients. The presence of aRP antibodies positively predicts patients with psychiatric manifestations in general and mood disorders in

  11. Designing Fluorinated Proteins.

    PubMed

    Marsh, E N G

    2016-01-01

    As methods to incorporate noncanonical amino acid residues into proteins have become more powerful, interest in their use to modify the physical and biological properties of proteins and enzymes has increased. This chapter discusses the use of highly fluorinated analogs of hydrophobic amino acids, for example, hexafluoroleucine, in protein design. In particular, fluorinated residues have proven to be generally effective in increasing the thermodynamic stability of proteins. The chapter provides an overview of the different fluorinated amino acids that have been used in protein design and the various methods available for producing fluorinated proteins. It discusses model proteins systems into which highly fluorinated amino acids have been introduced and the reasons why fluorinated residues are generally stabilizing, with particular reference to thermodynamic and structural studies from our laboratory. Lastly, details of the methodology we have developed to measure the thermodynamic stability of oligomeric fluorinated proteins are presented, as this may be generally applicable to many proteins. PMID:27586337

  12. Surface Mediated Protein Disaggregation

    NASA Astrophysics Data System (ADS)

    Radhakrishna, Mithun; Kumar, Sanat K.

    2014-03-01

    Preventing protein aggregation is of both biological and industrial importance. Biologically these aggregates are known to cause amyloid type diseases like Alzheimer's and Parkinson's disease. Protein aggregation leads to reduced activity of the enzymes in industrial applications. Inter-protein interactions between the hydrophobic residues of the protein are known to be the major driving force for protein aggregation. In the current paper we show how surface chemistry and curvature can be tuned to mitigate these inter-protein interactions. Our results calculated in the framework of the Hydrophobic-Polar (HP) lattice model show that, inter-protein interactions can be drastically reduced by increasing the surface hydrophobicity to a critical value corresponding to the adsorption transition of the protein. At this value of surface hydrophobicity, proteins lose inter-protein contacts to gain surface contacts and thus the surface helps in reducing the inter-protein interactions. Further, we show that the adsorption of the proteins inside hydrophobic pores of optimal sizes are most efficient both in reducing inter-protein contacts and simultaneously retaining most of the native-contacts due to strong protein-surface interactions coupled with stabilization due to the confinement. Department of Energy (Grant No DE-FG02-11ER46811).

  13. PINT: Protein-protein Interactions Thermodynamic Database.

    PubMed

    Kumar, M D Shaji; Gromiha, M Michael

    2006-01-01

    The first release of Protein-protein Interactions Thermodynamic Database (PINT) contains >1500 data of several thermodynamic parameters along with sequence and structural information, experimental conditions and literature information. Each entry contains numerical data for the free energy change, dissociation constant, association constant, enthalpy change, heat capacity change and so on of the interacting proteins upon binding, which are important for understanding the mechanism of protein-protein interactions. PINT also includes the name and source of the proteins involved in binding, their Protein Information Resource, SWISS-PROT and Protein Data Bank (PDB) codes, secondary structure and solvent accessibility of residues at mutant positions, measuring methods, experimental conditions, such as buffers, ions and additives, and literature information. A WWW interface facilitates users to search data based on various conditions, feasibility to select the terms for output and different sorting options. Further, PINT is cross-linked with other related databases, PIR, SWISS-PROT, PDB and NCBI PUBMED literature database. The database is freely available at http://www.bioinfodatabase.com/pint/index.html. PMID:16381844

  14. The enteropathogenic E. coli effector EspH promotes actin pedestal formation and elongation via WASP-interacting protein (WIP)

    PubMed Central

    Wong, Alexander R. C.; Raymond, Benoit; Collins, James W.; Crepin, Valerie F.; Frankel, Gad

    2016-01-01

    Summary Enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC) are diarrheagenic pathogens that colonize the gut mucosa via attaching-and-effacing lesion formation. EPEC and EHEC utilize a type III secretion system (T3SS) to translocate effector proteins that subvert host cell signalling to sustain colonization and multiplication. EspH, a T3SS effector that modulates actin dynamics, was implicated in the elongation of the EHEC actin pedestals. In this study we found that EspH is necessary for both efficient pedestal formation and pedestal elongation during EPEC infection. We report that EspH induces actin polymerization at the bacterial attachment sites independently of the Tir tyrosine residues Y474 and Y454, which are implicated in binding Nck and IRSp53/ITRKS respectively. Moreover, EspH promotes recruitment of neural Wiskott–Aldrich syndrome protein (N-WASP) and the Arp2/3 complex to the bacterial attachment site, in a mechanism involving the C-terminus of Tir and the WH1 domain of N-WASP. Dominant negative of WASP-interacting protein (WIP), which binds the N-WASP WH1 domain, diminished EspH-mediated actin polymerization. This study implicates WIP in EPEC-mediated actin polymerization and pedestal elongation and represents the first instance whereby N-WASP is efficiently recruited to the EPEC attachment sites independently of the Tir:Nck and Tir:IRTKS/IRSp53 pathways. Our study reveals the intricacies of Tir and EspH-mediated actin signalling pathways that comprise of distinct, convergent and synergistic signalling cascades. PMID:22372637

  15. DNA mimicry by proteins.

    PubMed

    Dryden, D T F; Tock, M R

    2006-04-01

    It has been discovered recently, via structural and biophysical analyses, that proteins can mimic DNA structures in order to inhibit proteins that would normally bind to DNA. Mimicry of the phosphate backbone of DNA, the hydrogen-bonding properties of the nucleotide bases and the bending and twisting of the DNA double helix are all present in the mimics discovered to date. These mimics target a range of proteins and enzymes such as DNA restriction enzymes, DNA repair enzymes, DNA gyrase and nucleosomal and nucleoid-associated proteins. The unusual properties of these protein DNA mimics may provide a foundation for the design of targeted inhibitors of DNA-binding proteins. PMID:16545103

  16. CIP4 coordinates with phospholipids and actin-associated proteins to localize to the protruding edge and produce actin ribs and veils.

    PubMed

    Saengsawang, Witchuda; Taylor, Kendra L; Lumbard, Derek C; Mitok, Kelly; Price, Amanda; Pietila, Lauren; Gomez, Timothy M; Dent, Erik W

    2013-06-01

    Cdc42-interacting protein 4 (CIP4), a member of the F-BAR family of proteins, plays important roles in a variety of cellular events by regulating both membrane and actin dynamics. In many cell types, CIP4 functions in vesicle formation, endocytosis and membrane tubulation. However, recent data indicate that CIP4 is also involved in protrusion in some cell types, including cancer cells (lamellipodia and invadopodia) and neurons (ribbed lamellipodia and veils). In neurons, CIP4 localizes specifically to extending protrusions and functions to limit neurite outgrowth early in development. The mechanism by which CIP4 localizes to the protruding edge membrane and induces lamellipodial/veil protrusion and actin rib formation is not known. Here, we show that CIP4 localization to the protruding edge of neurons is dependent on both the phospholipid content of the plasma membrane and the underlying organization of actin filaments. Inhibiting phosphatidylinositol (3,4,5)-trisphosphate (PIP3) production decreases CIP4 at the membrane. CIP4 localization to the protruding edge is also dependent on Rac1/WAVE1, rather than Cdc42/N-WASP. Capping actin filaments with low concentrations of cytochalasin D or by overexpressing capping protein dramatically decreases CIP4 at the protruding edge, whereas inactivating Arp2/3 drives CIP4 to the protruding edge. We also demonstrate that CIP4 dynamically colocalizes with Ena/VASP and DAAM1, two proteins known to induce unbranched actin filament arrays and play important roles in neuronal development. Together, this is the first study to show that the localization of an F-BAR protein depends on both actin filament architecture and phospholipids at the protruding edge of developing neurons. PMID:23572514

  17. Physics of protein motility and motor proteins

    NASA Astrophysics Data System (ADS)

    Kolomeisky, Anatoly B.

    2013-09-01

    Motor proteins are enzymatic molecules that transform chemical energy into mechanical motion and work. They are critically important for supporting various cellular activities and functions. In the last 15 years significant progress in understanding the functioning of motor proteins has been achieved due to revolutionary breakthroughs in single-molecule experimental techniques and strong advances in theoretical modelling. However, microscopic mechanisms of protein motility are still not well explained, and the collective efforts of many scientists are needed in order to solve these complex problems. In this special section the reader will find the latest advances on the difficult road to mapping motor proteins dynamics in various systems. Recent experimental developments have allowed researchers to monitor and to influence the activity of single motor proteins with a high spatial and temporal resolution. It has stimulated significant theoretical efforts to understand the non-equilibrium nature of protein motility phenomena. The latest results from all these advances are presented and discussed in this special section. We would like to thank the scientists from all over the world who have reported their latest research results for this special section. We are also grateful to the staff and editors of Journal of Physics: Condensed Matter for their invaluable help in handling all the administrative and refereeing activities. The field of motor proteins and protein motility is fast moving, and we hope that this collection of articles will be a useful source of information in this highly interdisciplinary area. Physics of protein motility and motor proteins contents Physics of protein motility and motor proteinsAnatoly B Kolomeisky Identification of unique interactions between the flexible linker and the RecA-like domains of DEAD-box helicase Mss116 Yuan Zhang, Mirkó Palla, Andrew Sun and Jung-Chi Liao The load dependence of the physical properties of a molecular motor

  18. Protein C blood test

    MedlinePlus

    ... a normal substance in the body that prevents blood clotting. A blood test can be done to see ... history of blood clots. Protein C helps control blood clotting. A lack of this protein or problem with ...

  19. Protein S blood test

    MedlinePlus

    ... a normal substance in your body that prevents blood clotting. A blood test can be done to see ... family history of blood clots. Protein S helps control blood clotting. A lack of this protein or problem with ...

  20. Protein electrophoresis - urine

    MedlinePlus

    ... nephropathy Kidney failure Multiple myeloma Nephrotic syndrome Acute urinary tract infection Risks There are no risks associated with this ... Primary amyloidosis Protein in diet Protein urine test Urinary tract infection - adults Update Date 5/29/2014 Updated by: ...

  1. [Protein-losing enteropathy].

    PubMed

    Amiot, A

    2015-07-01

    Protein-losing enteropathy is a rare syndrome of gastrointestinal protein loss. The primary causes can be classified into lymphatic leakage due to increased interstitial pressure and increased leakage of protein-rich fluids due to erosive or non-erosive gastrointestinal disorders. The diagnosis of protein-losing enteropathy should be considered in patients with chronic diarrhea and peripheral oedema. The diagnosis of protein-losing enteropathy is most commonly based on the determination of fecal alpha-1 antitrypsin clearance. Most protein-losing enteropathy cases are the result of either lymphatic obstruction or a variety of gastrointestinal disorders and cardiac diseases, while primary intestinal lymphangiectasia (Waldmann's disease) is less common. Treatment of protein-losing enteropathy targets the underlying disease but also includes dietary modification, such as high-protein and low-fat diet along with medium-chain triglyceride supplementation. PMID:25618488

  2. Learning about Proteins

    MedlinePlus

    ... body, and protecting you from disease. All About Amino Acids When you eat foods that contain protein, the ... called amino (say: uh-MEE-no) acids. The amino acids then can be reused to make the proteins ...

  3. Hydrodynamic effects in proteins

    NASA Astrophysics Data System (ADS)

    Szymczak, Piotr; Cieplak, Marek

    2011-01-01

    Experimental and numerical results pertaining to flow-induced effects in proteins are reviewed. Special emphasis is placed on shear-induced unfolding and on the role of solvent mediated hydrodynamic interactions in the conformational transitions in proteins.

  4. Hydrodynamic effects in proteins.

    PubMed

    Szymczak, Piotr; Cieplak, Marek

    2011-01-26

    Experimental and numerical results pertaining to flow-induced effects in proteins are reviewed. Special emphasis is placed on shear-induced unfolding and on the role of solvent mediated hydrodynamic interactions in the conformational transitions in proteins. PMID:21406855

  5. Understanding protein folding: small proteins in silico.

    PubMed

    Zimmermann, Olav; Hansmann, Ulrich H E

    2008-01-01

    Recent improvements in methodology and increased computer power now allow atomistic computer simulations of protein folding. We briefly review several advanced Monte Carlo algorithms that have contributed to this development. Details of folding simulations of three designed mini proteins are shown. Adding global translations and rotations has allowed us to handle multiple chains and to simulate the aggregation of six beta-amyloid fragments. In a different line of research we have developed several algorithms to predict local features from sequence. In an outlook we sketch how such biasing could extend the application spectrum of Monte Carlo simulations to structure prediction of larger proteins. PMID:18036571

  6. Imaging Protein-protein Interactions in vivo

    PubMed Central

    Seegar, Tom; Barton, William

    2010-01-01

    Protein-protein interactions are a hallmark of all essential cellular processes. However, many of these interactions are transient, or energetically weak, preventing their identification and analysis through traditional biochemical methods such as co-immunoprecipitation. In this regard, the genetically encodable fluorescent proteins (GFP, RFP, etc.) and their associated overlapping fluorescence spectrum have revolutionized our ability to monitor weak interactions in vivo using Förster resonance energy transfer (FRET)1-3. Here, we detail our use of a FRET-based proximity assay for monitoring receptor-receptor interactions on the endothelial cell surface. PMID:20972411

  7. CSF myelin basic protein

    MedlinePlus

    CSF myelin basic protein is a test to measure the level of myelin basic protein (MBP) in the cerebrospinal fluid (CSF). The CSF ... less than 4 ng/mL of myelin basic protein in the CSF. Normal value ranges may vary ...

  8. Modeling Protein Domain Function

    ERIC Educational Resources Information Center

    Baker, William P.; Jones, Carleton "Buck"; Hull, Elizabeth

    2007-01-01

    This simple but effective laboratory exercise helps students understand the concept of protein domain function. They use foam beads, Styrofoam craft balls, and pipe cleaners to explore how domains within protein active sites interact to form a functional protein. The activity allows students to gain content mastery and an understanding of the…

  9. Palmitoylation of Hedgehog proteins.

    PubMed

    Buglino, John A; Resh, Marilyn D

    2012-01-01

    Hedgehog (Hh) proteins are secreted signaling proteins that contain amide-linked palmitate at the N-terminus and cholesterol at the C-terminus. Palmitoylation of Hh proteins is critical for effective long- and short-range signaling. The palmitoylation reaction occurs during transit of Hh through the secretory pathway, most likely in the lumen of the ER. Attachment of palmitate to Hh proteins is independent of cholesterol modification and autoprocessing and is catalyzed by Hhat (Hedgehog acyltransferase). Hhat is a member of the membrane bound O-acyltransferase (MBOAT) family, a subgroup of multipass membrane proteins that catalyze transfer of fatty acyl groups to lipids and proteins. Several classes of secreted proteins have recently been shown to be substrates for MBOAT acyltransferases, including Hh proteins and Spitz (palmitoylated by Hhat), Wg/Wnt proteins (modified with palmitate and/or palmitoleate by Porcupine) and ghrelin (octanoylated by ghrelin O-acyltransferase). These findings highlight protein fatty acylation as a mechanism that not only influences membrane binding of intracellular proteins but also regulates the signaling range and efficacy of secreted proteins. PMID:22391306

  10. Protein electrophoresis - serum

    MedlinePlus

    Normal value ranges are: Total protein: 6.4 to 8.3 g/dL (grams per deciliter) Albumin: 3.5 to 5.0 g/dL Alpha-1 ... Decreased total protein may indicate: Abnormal loss of protein from the digestive tract or the inability of the digestive tract ...

  11. CSF total protein

    MedlinePlus

    CSF total protein is a test to determine the amount of protein in your spinal fluid, also called cerebrospinal fluid (CSF). ... The normal protein range varies from lab to lab, but is typically about 15 to 60 mg/dL. Note: mg/dL = ...

  12. Modeling Protein Self Assembly

    ERIC Educational Resources Information Center

    Baker, William P.; Jones, Carleton Buck; Hull, Elizabeth

    2004-01-01

    Understanding the structure and function of proteins is an important part of the standards-based science curriculum. Proteins serve vital roles within the cell and malfunctions in protein self assembly are implicated in degenerative diseases. Experience indicates that this topic is a difficult one for many students. We have found that the concept…

  13. Texturized dairy proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dairy proteins are amenable to structural modifications induced by high temperature, shear and moisture; in particular, whey proteins can change conformation to new unfolded states. The change in protein state is a basis for creating new foods. The dairy products, nonfat dried milk (NDM), whey prote...

  14. Destabilized bioluminescent proteins

    DOEpatents

    Allen, Michael S.; Rakesh, Gupta; Gary, Sayler S.

    2007-07-31

    Purified nucleic acids, vectors and cells containing a gene cassette encoding at least one modified bioluminescent protein, wherein the modification includes the addition of a peptide sequence. The duration of bioluminescence emitted by the modified bioluminescent protein is shorter than the duration of bioluminescence emitted by an unmodified form of the bioluminescent protein.

  15. Protein - Which is Best?

    PubMed

    Hoffman, Jay R; Falvo, Michael J

    2004-09-01

    Protein intake that exceeds the recommended daily allowance is widely accepted for both endurance and power athletes. However, considering the variety of proteins that are available much less is known concerning the benefits of consuming one protein versus another. The purpose of this paper is to identify and analyze key factors in order to make responsible recommendations to both the general and athletic populations. Evaluation of a protein is fundamental in determining its appropriateness in the human diet. Proteins that are of inferior content and digestibility are important to recognize and restrict or limit in the diet. Similarly, such knowledge will provide an ability to identify proteins that provide the greatest benefit and should be consumed. The various techniques utilized to rate protein will be discussed. Traditionally, sources of dietary protein are seen as either being of animal or vegetable origin. Animal sources provide a complete source of protein (i.e. containing all essential amino acids), whereas vegetable sources generally lack one or more of the essential amino acids. Animal sources of dietary protein, despite providing a complete protein and numerous vitamins and minerals, have some health professionals concerned about the amount of saturated fat common in these foods compared to vegetable sources. The advent of processing techniques has shifted some of this attention and ignited the sports supplement marketplace with derivative products such as whey, casein and soy. Individually, these products vary in quality and applicability to certain populations. The benefits that these particular proteins possess are discussed. In addition, the impact that elevated protein consumption has on health and safety issues (i.e. bone health, renal function) are also reviewed. Key PointsHigher protein needs are seen in athletic populations.Animal proteins is an important source of protein, however potential health concerns do exist from a diet of protein

  16. Protein crystallization with paper

    NASA Astrophysics Data System (ADS)

    Matsuoka, Miki; Kakinouchi, Keisuke; Adachi, Hiroaki; Maruyama, Mihoko; Sugiyama, Shigeru; Sano, Satoshi; Yoshikawa, Hiroshi Y.; Takahashi, Yoshinori; Yoshimura, Masashi; Matsumura, Hiroyoshi; Murakami, Satoshi; Inoue, Tsuyoshi; Mori, Yusuke; Takano, Kazufumi

    2016-05-01

    We developed a new protein crystallization method that incorporates paper. A small piece of paper, such as facial tissue or KimWipes, was added to a drop of protein solution in the traditional sitting drop vapor diffusion technique, and protein crystals grew by incorporating paper. By this method, we achieved the growth of protein crystals with reducing osmotic shock. Because the technique is very simple and the materials are easy to obtain, this method will come into wide use for protein crystallization. In the future, it could be applied to nanoliter-scale crystallization screening on a paper sheet such as in inkjet printing.

  17. Highly thermostable fluorescent proteins

    DOEpatents

    Bradbury, Andrew M.; Waldo, Geoffrey S.; Kiss, Csaba

    2011-03-22

    Thermostable fluorescent proteins (TSFPs), methods for generating these and other stability-enhanced proteins, polynucleotides encoding such proteins, and assays and method for using the TSFPs and TSFP-encoding nucleic acid molecules are provided. The TSFPs of the invention show extremely enhanced levels of stability and thermotolerance. In one case, for example, a TSFP of the invention is so stable it can be heated to 99.degree. C. for short periods of time without denaturing, and retains 85% of its fluorescence when heated to 80.degree. C. for several minutes. The invention also provides a method for generating stability-enhanced variants of a protein, including but not limited to fluorescent proteins.

  18. Highly thermostable fluorescent proteins

    DOEpatents

    Bradbury, Andrew M.; Waldo, Geoffrey S.; Kiss, Csaba

    2012-05-01

    Thermostable fluorescent proteins (TSFPs), methods for generating these and other stability-enhanced proteins, polynucleotides encoding such proteins, and assays and method for using the TSFPs and TSFP-encoding nucleic acid molecules are provided. The TSFPs of the invention show extremely enhanced levels of stability and thermotolerance. In one case, for example, a TSFP of the invention is so stable it can be heated to 99.degree. C. for short periods of time without denaturing, and retains 85% of its fluorescence when heated to 80.degree. C. for several minutes. The invention also provides a method for generating stability-enhanced variants of a protein, including but not limited to fluorescent proteins.

  19. Highly thermostable fluorescent proteins

    DOEpatents

    Bradbury, Andrew M.; Waldo, Geoffrey S.; Kiss, Csaba

    2011-11-29

    Thermostable fluorescent proteins (TSFPs), methods for generating these and other stability-enhanced proteins, polynucleotides encoding such proteins, and assays and method for using the TSFPs and TSFP-encoding nucleic acid molecules are provided. The TSFPs of the invention show extremely enhanced levels of stability and thermotolerance. In one case, for example, a TSFP of the invention is so stable it can be heated to 99.degree. C. for short periods of time without denaturing, and retains 85% of its fluorescence when heated to 80.degree. C. for several minutes. The invention also provides a method for generating stability-enhanced variants of a protein, including but not limited to fluorescent proteins.

  20. Selective Precipitation of Proteins.

    PubMed

    Matulis, Daumantas

    2016-01-01

    Selective precipitation of proteins can be used as a bulk method to recover the majority of proteins from a crude lysate, as a selective method to fractionate a subset of proteins from a protein solution, or as a very specific method to recover a single protein of interest from a purification step. This unit describes a number of methods suitable for selective precipitation. In each of the protocols that are outlined, the physical or chemical basis of the precipitation process, the parameters that can be varied for optimization, and the basic steps for developing an optimized precipitation are described. PMID:26836410

  1. Forces Stabilizing Proteins

    PubMed Central

    Pace, C. Nick; Scholtz, J. Martin; Grimsley, Gerald R.

    2014-01-01

    The goal of this article is to summarize what has been learned about the major forces stabilizing proteins since the late 1980s when site-directed mutagenesis became possible. The following conclusions are derived from experimental studies of hydrophobic and hydrogen bonding variants. 1. Based on studies of 138 hydrophobic interaction variants in 11 proteins, burying a –CH2– group on folding contributes 1.1 ± 0.5 kcal/mol to protein stability. 2. The burial of nonpolar side chains contributes to protein stability in two ways: first, a term that depends on the removal of the side chains from water and, more importantly, the enhanced London dispersion forces that result from the tight packing in the protein interior. 3. Based on studies of 151 hydrogen bonding variants in 15 proteins, forming a hydrogen bond on folding contributes 1.1 ± 0.8 kcal/mol to protein stability. 4. The contribution of hydrogen bonds to protein stability is strongly context dependent. 5. Hydrogen bonds by side chains and peptide groups make similar contributions to protein stability. 6. Polar group burial can make a favorable contribution to protein stability even if the polar group is not hydrogen bonded. 7. Hydrophobic interactions and hydrogen bonds both make large contributions to protein stability. PMID:24846139

  2. Mechanism of protein decarbonylation.

    PubMed

    Wong, Chi-Ming; Marcocci, Lucia; Das, Dividutta; Wang, Xinhong; Luo, Haibei; Zungu-Edmondson, Makhosazane; Suzuki, Yuichiro J

    2013-12-01

    Ligand/receptor stimulation of cells promotes protein carbonylation that is followed by the decarbonylation process, which might involve thiol-dependent reduction (C.M. Wong et al., Circ. Res. 102:301-318; 2008). This study further investigated the properties of this protein decarbonylation mechanism. We found that the thiol-mediated reduction of protein carbonyls is dependent on heat-labile biologic components. Cysteine and glutathione were efficient substrates for decarbonylation. Thiols decreased the protein carbonyl content, as detected by 2,4-dinitrophenylhydrazine, but not the levels of malondialdehyde or 4-hydroxynonenal protein adducts. Mass spectrometry identified proteins that undergo thiol-dependent decarbonylation, which include peroxiredoxins. Peroxiredoxin-2 and -6 were carbonylated and subsequently decarbonylated in response to the ligand/receptor stimulation of cells. siRNA knockdown of glutaredoxin inhibited the decarbonylation of peroxiredoxin. These results strengthen the concept that thiol-dependent decarbonylation defines the kinetics of protein carbonylation signaling. PMID:24044890

  3. Pigment-protein complexes

    SciTech Connect

    Siegelman, H W

    1980-01-01

    The photosynthetically-active pigment protein complexes of procaryotes and eucaryotes include chlorophyll proteins, carotenochlorophyll proteins, and biliproteins. They are either integral components or attached to photosynthetic membranes. Detergents are frequently required to solubilize the pigment-protein complexes. The membrane localization and detergent solubilization strongly suggest that the pigment-protein complexes are bound to the membranes by hydrophobic interactions. Hydrophobic interactions of proteins are characterized by an increase in entropy. Their bonding energy is directly related to temperature and ionic strength. Hydrophobic-interaction chromatography, a relatively new separation procedure, can furnish an important method for the purification of pigment-protein complexes. Phycobilisome purification and properties provide an example of the need to maintain hydrophobic interactions to preserve structure and function.

  4. Protein solubility modeling

    NASA Technical Reports Server (NTRS)

    Agena, S. M.; Pusey, M. L.; Bogle, I. D.

    1999-01-01

    A thermodynamic framework (UNIQUAC model with temperature dependent parameters) is applied to model the salt-induced protein crystallization equilibrium, i.e., protein solubility. The framework introduces a term for the solubility product describing protein transfer between the liquid and solid phase and a term for the solution behavior describing deviation from ideal solution. Protein solubility is modeled as a function of salt concentration and temperature for a four-component system consisting of a protein, pseudo solvent (water and buffer), cation, and anion (salt). Two different systems, lysozyme with sodium chloride and concanavalin A with ammonium sulfate, are investigated. Comparison of the modeled and experimental protein solubility data results in an average root mean square deviation of 5.8%, demonstrating that the model closely follows the experimental behavior. Model calculations and model parameters are reviewed to examine the model and protein crystallization process. Copyright 1999 John Wiley & Sons, Inc.

  5. Laser-ARPES studies of BSCCO-BASED cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Douglas, J. F.; Koralek, J. D.; Sun, Z.; Plumb, N. C.; Wang, Q.; Reber, T. J.; Griffith, J. D.; Aiura, Y.; Oka, K.; Eisaki, H.; Dessau, D. S.; Devereaux, T. P.; Johnson, S. S.

    2007-03-01

    Utilizing 6 eV and 7 eV laser light, we have performed high-resolution ANGLE RESOLVED PHOTOEMISSION studies of the BSCCO family of superconductors. This higher resolution, in both energy and momentum, has allowed the observation of interesting new doping- and temperature-dependent features in the nodal and near nodal dispersions in these materials.

  6. Insights on the Cuprate High Energy Anomaly Observed in ARPES

    SciTech Connect

    Moritz, Brian

    2011-08-16

    Recently, angle-resolved photoemission spectroscopy has been used to highlight an anomalously large band renormalization at high binding energies in cuprate superconductors: the high energy 'waterfall' or high energy anomaly (HEA). The anomaly is present for both hole- and electron-doped cuprates as well as the half-filled parent insulators with different energy scales arising on either side of the phase diagram. While photoemission matrix elements clearly play a role in changing the aesthetic appearance of the band dispersion, i.e. creating a 'waterfall'-like appearance, they provide an inadequate description for the physics that underlies the strong band renormalization giving rise to the HEA. Model calculations of the single-band Hubbard Hamiltonian showcase the role played by correlations in the formation of the HEA and uncover significant differences in the HEA energy scale for hole- and electron-doped cuprates. In addition, this approach properly captures the transfer of spectral weight accompanying doping in a correlated material and provides a unifying description of the HEA across both sides of the cuprate phase diagram. We find that the anomaly demarcates a transition, or cross-over, from a quasiparticle band at low binding energies near the Fermi level to valence bands at higher binding energy, assumed to be of strong oxygen character.

  7. Protein kinesis: The dynamics of protein trafficking and stability

    SciTech Connect

    1995-12-31

    The purpose of this conference is to provide a multidisciplinary forum for exchange of state-of-the-art information on protein kinesis. This volume contains abstracts of papers in the following areas: protein folding and modification in the endoplasmic reticulum; protein trafficking; protein translocation and folding; protein degradation; polarity; nuclear trafficking; membrane dynamics; and protein import into organelles.

  8. Phage display of proteins.

    PubMed

    Kościelska, K; Kiczak, L; Kasztura, M; Wesołowska, O; Otlewski, J

    1998-01-01

    In recent years the phage display approach has become an increasingly popular method in protein research. This method enables the presentation of large peptide and protein libraries on the surface of phage particles from which molecules of desired functional property(ies) can be rapidly selected. The great advantage of this method is a direct linkage between an observed phenotype and encapsulated genotype, which allows fast determination of selected sequences. The phage display approach is a powerful tool in generating highly potent biomolecules, including: search for specific antibodies, determining enzyme specificity, exploring protein-protein and protein-DNA interactions, minimizing proteins, introducing new functions into different protein scaffolds, and searching sequence space of protein folding. In this article many examples are given to illustrate that this technique can be used in different fields of protein science. The phage display has a potential of the natural evolution and its possibilities are far beyond rational prediction. Assuming that we can design the selection agents and conditions we should be able to engineer any desired protein function or feature. PMID:9918498

  9. Energy design for protein-protein interactions

    PubMed Central

    Ravikant, D. V. S.; Elber, Ron

    2011-01-01

    Proteins bind to other proteins efficiently and specifically to carry on many cell functions such as signaling, activation, transport, enzymatic reactions, and more. To determine the geometry and strength of binding of a protein pair, an energy function is required. An algorithm to design an optimal energy function, based on empirical data of protein complexes, is proposed and applied. Emphasis is made on negative design in which incorrect geometries are presented to the algorithm that learns to avoid them. For the docking problem the search for plausible geometries can be performed exhaustively. The possible geometries of the complex are generated on a grid with the help of a fast Fourier transform algorithm. A novel formulation of negative design makes it possible to investigate iteratively hundreds of millions of negative examples while monotonically improving the quality of the potential. Experimental structures for 640 protein complexes are used to generate positive and negative examples for learning parameters. The algorithm designed in this work finds the correct binding structure as the lowest energy minimum in 318 cases of the 640 examples. Further benchmarks on independent sets confirm the significant capacity of the scoring function to recognize correct modes of interactions. PMID:21842951

  10. Modeling Protein Expression and Protein Signaling Pathways

    PubMed Central

    Telesca, Donatello; Müller, Peter; Kornblau, Steven M.; Suchard, Marc A.; Ji, Yuan

    2015-01-01

    High-throughput functional proteomic technologies provide a way to quantify the expression of proteins of interest. Statistical inference centers on identifying the activation state of proteins and their patterns of molecular interaction formalized as dependence structure. Inference on dependence structure is particularly important when proteins are selected because they are part of a common molecular pathway. In that case, inference on dependence structure reveals properties of the underlying pathway. We propose a probability model that represents molecular interactions at the level of hidden binary latent variables that can be interpreted as indicators for active versus inactive states of the proteins. The proposed approach exploits available expert knowledge about the target pathway to define an informative prior on the hidden conditional dependence structure. An important feature of this prior is that it provides an instrument to explicitly anchor the model space to a set of interactions of interest, favoring a local search approach to model determination. We apply our model to reverse-phase protein array data from a study on acute myeloid leukemia. Our inference identifies relevant subpathways in relation to the unfolding of the biological process under study. PMID:26246646

  11. Protein-protein docking with backbone flexibility.

    PubMed

    Wang, Chu; Bradley, Philip; Baker, David

    2007-10-19

    Computational protein-protein docking methods currently can create models with atomic accuracy for protein complexes provided that the conformational changes upon association are restricted to the side chains. However, it remains very challenging to account for backbone conformational changes during docking, and most current methods inherently keep monomer backbones rigid for algorithmic simplicity and computational efficiency. Here we present a reformulation of the Rosetta docking method that incorporates explicit backbone flexibility in protein-protein docking. The new method is based on a "fold-tree" representation of the molecular system, which seamlessly integrates internal torsional degrees of freedom and rigid-body degrees of freedom. Problems with internal flexible regions ranging from one or more loops or hinge regions to all of one or both partners can be readily treated using appropriately constructed fold trees. The explicit treatment of backbone flexibility improves both sampling in the vicinity of the native docked conformation and the energetic discrimination between near-native and incorrect models. PMID:17825317

  12. Energy design for protein-protein interactions

    NASA Astrophysics Data System (ADS)

    Ravikant, D. V. S.; Elber, Ron

    2011-08-01

    Proteins bind to other proteins efficiently and specifically to carry on many cell functions such as signaling, activation, transport, enzymatic reactions, and more. To determine the geometry and strength of binding of a protein pair, an energy function is required. An algorithm to design an optimal energy function, based on empirical data of protein complexes, is proposed and applied. Emphasis is made on negative design in which incorrect geometries are presented to the algorithm that learns to avoid them. For the docking problem the search for plausible geometries can be performed exhaustively. The possible geometries of the complex are generated on a grid with the help of a fast Fourier transform algorithm. A novel formulation of negative design makes it possible to investigate iteratively hundreds of millions of negative examples while monotonically improving the quality of the potential. Experimental structures for 640 protein complexes are used to generate positive and negative examples for learning parameters. The algorithm designed in this work finds the correct binding structure as the lowest energy minimum in 318 cases of the 640 examples. Further benchmarks on independent sets confirm the significant capacity of the scoring function to recognize correct modes of interactions.

  13. Mechanisms Regulating Protein Localization.

    PubMed

    Bauer, Nicholas C; Doetsch, Paul W; Corbett, Anita H

    2015-10-01

    Cellular functions are dictated by protein content and activity. There are numerous strategies to regulate proteins varying from modulating gene expression to post-translational modifications. One commonly used mode of regulation in eukaryotes is targeted localization. By specifically redirecting the localization of a pool of existing protein, cells can achieve rapid changes in local protein function. Eukaryotic cells have evolved elegant targeting pathways to direct proteins to the appropriate cellular location or locations. Here, we provide a general overview of these localization pathways, with a focus on nuclear and mitochondrial transport, and present a survey of the evolutionarily conserved regulatory strategies identified thus far. We end with a description of several specific examples of proteins that exploit localization as an important mode of regulation. PMID:26172624

  14. Electrophoretic separation of proteins.

    PubMed

    Chakavarti, Bulbul; Chakavarti, Deb

    2008-01-01

    Electrophoresis is used to separate complex mixtures of proteins (e.g., from cells, subcellular fractions, column fractions, or immunoprecipitates), to investigate subunit compositions, and to verify homogeneity of protein samples. It can also serve to purify proteins for use in further applications. In polyacrylamide gel electrophoresis, proteins migrate in response to an electrical field through pores in a polyacrylamide gel matrix; pore size decreases with increasing acrylamide concentration. The combination of pore size and protein charge, size, and shape determines the migration rate of the protein. In this unit, the standard Laemmli method is described for discontinuous gel electrophoresis under denaturing conditions, i.e., in the presence of sodium dodecyl sulfate (SDS). PMID:19066548

  15. Outer membrane protein purification.

    PubMed

    Arigita, C; Jiskoot, W; Graaf, M R; Kersten, G F

    2001-01-01

    The major outer membrane proteins (OMPs) from Neisseria meningitidis, which are expressed at high levels, are subdivided in five classes based on molecular weight (1,2) (see Table 1). Table 1 Major Meningococcal Outer-Membrane Proteins Outer-membrane proteins Name Molecular maass Function/characteristics Class 1 PorA 44-47 kDa Porin Class 2/3 PorB 37-42 kDa Porin Class 4 Rmp Reductionmodifiableprotein, unknown Class 5 Opa 26-30 kDa Adhesion,opacity protein Opc 25 kDa Invasion, opacity protein Iron-regulated proteins Mirp 37 kDa Iron acquisition (?);majoriron-regulatedprotein FrpB 70 kDa Ferric enterobactin receptor (also FetA) Adapted from ref. (1). PMID:21336748

  16. Biofilm Matrix Proteins

    PubMed Central

    Fong, Jiunn N. C.; Yildiz, Fitnat H.

    2015-01-01

    Proteinaceous components of the biofilm matrix include secreted extracellular proteins, cell surface adhesins and protein subunits of cell appendages such as flagella and pili. Biofilm matrix proteins play diverse roles in biofilm formation and dissolution. They are involved in attaching cells to surfaces, stabilizing the biofilm matrix via interactions with exopolysaccharide and nucleic acid components, developing three-dimensional biofilm architectures, and dissolving biofilm matrix via enzymatic degradation of polysaccharides, proteins, and nucleic acids. In this chapter, we will review functions of matrix proteins in a selected set of microorganisms, studies of the matrix proteomes of Vibrio cholerae and Pseudomonas aeruginosa, and roles of outer membrane vesicles and of nucleoid-binding proteins in biofilm formation. PMID:26104709

  17. Principles of Flexible Protein-Protein Docking

    PubMed Central

    Andrusier, Nelly; Mashiach, Efrat; Nussinov, Ruth; Wolfson, Haim J.

    2008-01-01

    Treating flexibility in molecular docking is a major challenge in cell biology research. Here we describe the background and the principles of existing flexible protein-protein docking methods, focusing on the algorithms and their rational. We describe how protein flexibility is treated in different stages of the docking process: in the preprocessing stage, rigid and flexible parts are identified and their possible conformations are modeled. This preprocessing provides information for the subsequent docking and refinement stages. In the docking stage, an ensemble of pre-generated conformations or the identified rigid domains may be docked separately. In the refinement stage, small-scale movements of the backbone and side-chains are modeled and the binding orientation is improved by rigid-body adjustments. For clarity of presentation, we divide the different methods into categories. This should allow the reader to focus on the most suitable method for a particular docking problem. PMID:18655061

  18. Antimicrobial proteins: From old proteins, new tricks.

    PubMed

    Smith, Valerie J; Dyrynda, Elisabeth A

    2015-12-01

    This review describes the main types of antimicrobial peptides (AMPs) synthesised by crustaceans, primarily those identified in shrimp, crayfish, crab and lobster. It includes an overview of their range of microbicidal activities and the current landscape of our understanding of their gene expression patterns in different body tissues. It further summarises how their expression might change following various types of immune challenges. The review further considers proteins or protein fragments from crustaceans that have antimicrobial properties but are more usually associated with other biological functions, or are derived from such proteins. It discusses how these unconventional AMPs might be generated at, or delivered to, sites of infection and how they might contribute to crustacean host defence in vivo. It also highlights recent work that is starting to reveal the extent of multi-functionality displayed by some decapod AMPs, particularly their participation in other aspects of host protection. Examples of such activities include proteinase inhibition, phagocytosis, antiviral activity and haematopoiesis. PMID:26320628

  19. Elastic proteins and elastomeric protein alloys.

    PubMed

    Aghaei-Ghareh-Bolagh, Behnaz; Mithieux, Suzanne M; Weiss, Anthony S

    2016-06-01

    The elastomeric proteins elastin and resilin have been used extensively in the fabrication of biomaterials for tissue engineering applications due to their unique mechanical and biological properties. Tropoelastin is the soluble monomer component of elastin. Tropoelastin and resilin are both highly elastic with high resilience, substantial extensibility, high durability and low energy loss, which makes them excellent candidates for the fabrication of elastic tissues that demand regular and repetitive movement like the skin, lung, blood vessels, muscles and vocal folds. Combinations of these proteins with silk fibroin further enhance their biomechanical and biological properties leading to a new class of protein alloy materials with versatile properties. In this review, the properties of tropoelastin-based and resilin-based biomaterials with and without silk are described in concert with examples of their applications in tissue engineering. PMID:26780495

  20. Protein Crystal Quality Studies

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Eddie Snell, Post-Doctoral Fellow the National Research Council (NRC) uses a reciprocal space mapping diffractometer for macromolecular crystal quality studies. The diffractometer is used in mapping the structure of macromolecules such as proteins to determine their structure and thus understand how they function with other proteins in the body. This is one of several analytical tools used on proteins crystallized on Earth and in space experiments. Photo credit: NASA/Marshall Space Flight Center (MSFC)

  1. Protein oxidation and peroxidation.

    PubMed

    Davies, Michael J

    2016-04-01

    Proteins are major targets for radicals and two-electron oxidants in biological systems due to their abundance and high rate constants for reaction. With highly reactive radicals damage occurs at multiple side-chain and backbone sites. Less reactive species show greater selectivity with regard to the residues targeted and their spatial location. Modification can result in increased side-chain hydrophilicity, side-chain and backbone fragmentation, aggregation via covalent cross-linking or hydrophobic interactions, protein unfolding and altered conformation, altered interactions with biological partners and modified turnover. In the presence of O2, high yields of peroxyl radicals and peroxides (protein peroxidation) are formed; the latter account for up to 70% of the initial oxidant flux. Protein peroxides can oxidize both proteins and other targets. One-electron reduction results in additional radicals and chain reactions with alcohols and carbonyls as major products; the latter are commonly used markers of protein damage. Direct oxidation of cysteine (and less commonly) methionine residues is a major reaction; this is typically faster than with H2O2, and results in altered protein activity and function. Unlike H2O2, which is rapidly removed by protective enzymes, protein peroxides are only slowly removed, and catabolism is a major fate. Although turnover of modified proteins by proteasomal and lysosomal enzymes, and other proteases (e.g. mitochondrial Lon), can be efficient, protein hydroperoxides inhibit these pathways and this may contribute to the accumulation of modified proteins in cells. Available evidence supports an association between protein oxidation and multiple human pathologies, but whether this link is causal remains to be established. PMID:27026395

  2. Protein oxidation and peroxidation

    PubMed Central

    Davies, Michael J.

    2016-01-01

    Proteins are major targets for radicals and two-electron oxidants in biological systems due to their abundance and high rate constants for reaction. With highly reactive radicals damage occurs at multiple side-chain and backbone sites. Less reactive species show greater selectivity with regard to the residues targeted and their spatial location. Modification can result in increased side-chain hydrophilicity, side-chain and backbone fragmentation, aggregation via covalent cross-linking or hydrophobic interactions, protein unfolding and altered conformation, altered interactions with biological partners and modified turnover. In the presence of O2, high yields of peroxyl radicals and peroxides (protein peroxidation) are formed; the latter account for up to 70% of the initial oxidant flux. Protein peroxides can oxidize both proteins and other targets. One-electron reduction results in additional radicals and chain reactions with alcohols and carbonyls as major products; the latter are commonly used markers of protein damage. Direct oxidation of cysteine (and less commonly) methionine residues is a major reaction; this is typically faster than with H2O2, and results in altered protein activity and function. Unlike H2O2, which is rapidly removed by protective enzymes, protein peroxides are only slowly removed, and catabolism is a major fate. Although turnover of modified proteins by proteasomal and lysosomal enzymes, and other proteases (e.g. mitochondrial Lon), can be efficient, protein hydroperoxides inhibit these pathways and this may contribute to the accumulation of modified proteins in cells. Available evidence supports an association between protein oxidation and multiple human pathologies, but whether this link is causal remains to be established. PMID:27026395

  3. Computer Models of Proteins

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Dr. Marc Pusey (seated) and Dr. Craig Kundrot use computers to analyze x-ray maps and generate three-dimensional models of protein structures. With this information, scientists at Marshall Space Flight Center can learn how proteins are made and how they work. The computer screen depicts a proten structure as a ball-and-stick model. Other models depict the actual volume occupied by the atoms, or the ribbon-like structures that are crucial to a protein's function.

  4. Pressure cryocooling protein crystals

    DOEpatents

    Kim, Chae Un; Gruner, Sol M.

    2011-10-04

    Preparation of cryocooled protein crystal is provided by use of helium pressurizing and cryocooling to obtain cryocooled protein crystal allowing collection of high resolution data and by heavier noble gas (krypton or xenon) binding followed by helium pressurizing and cryocooling to obtain cryocooled protein crystal for collection of high resolution data and SAD phasing simultaneously. The helium pressurizing is carried out on crystal coated to prevent dehydration or on crystal grown in aqueous solution in a capillary.

  5. Ect2/Pbl Acts via Rho and Polarity Proteins to Direct the Assembly of an Isotropic Actomyosin Cortex upon Mitotic Entry

    PubMed Central

    Rosa, André; Vlassaks, Evi; Pichaud, Franck; Baum, Buzz

    2015-01-01

    Summary Entry into mitosis is accompanied by profound changes in cortical actomyosin organization. Here, we delineate a pathway downstream of the RhoGEF Pbl/Ect2 that directs this process in a model epithelium. Our data suggest that the release of Pbl/Ect2 from the nucleus at mitotic entry drives Rho-dependent activation of Myosin-II and, in parallel, induces a switch from Arp2/3 to Diaphanous-mediated cortical actin nucleation that depends on Cdc42, aPKC, and Par6. At the same time, the mitotic relocalization of these apical protein complexes to more lateral cell surfaces enables Cdc42/aPKC/Par6 to take on a mitosis-specific function—aiding the assembly of a relatively isotropic metaphase cortex. Together, these data reveal how the repolarization and remodeling of the actomyosin cortex are coordinated upon entry into mitosis to provide cells with the isotropic and rigid form they need to undergo faithful chromosome segregation and division in a crowded tissue environment. PMID:25703349

  6. Protein-protein interactions as drug targets.

    PubMed

    Skwarczynska, Malgorzata; Ottmann, Christian

    2015-10-01

    Modulation of protein-protein interactions (PPIs) is becoming increasingly important in drug discovery and chemical biology. While a few years ago this 'target class' was deemed to be largely undruggable an impressing number of publications and success stories now show that targeting PPIs with small, drug-like molecules indeed is a feasible approach. Here, we summarize the current state of small-molecule inhibition and stabilization of PPIs and review the active molecules from a structural and medicinal chemistry angle, especially focusing on the key examples of iNOS, LFA-1 and 14-3-3. PMID:26510391

  7. Biomolecular membrane protein crystallization

    NASA Astrophysics Data System (ADS)

    Reddy Bolla, Jani; Su, Chih-Chia; Yu, Edward W.

    2012-07-01

    Integral membrane proteins comprise approximately 30% of the sequenced genomes, and there is an immediate need for their high-resolution structural information. Currently, the most reliable approach to obtain these structures is X-ray crystallography. However, obtaining crystals of membrane proteins that diffract to high resolution appears to be quite challenging, and remains a major obstacle in structural determination. This brief review summarizes a variety of methodologies for use in crystallizing these membrane proteins. Hopefully, by introducing the available methods, techniques, and providing a general understanding of membrane proteins, a rational decision can be made about now to crystallize these complex materials.

  8. Self assembling proteins

    DOEpatents

    Yeates, Todd O.; Padilla, Jennifer; Colovos, Chris

    2004-06-29

    Novel fusion proteins capable of self-assembling into regular structures, as well as nucleic acids encoding the same, are provided. The subject fusion proteins comprise at least two oligomerization domains rigidly linked together, e.g. through an alpha helical linking group. Also provided are regular structures comprising a plurality of self-assembled fusion proteins of the subject invention, and methods for producing the same. The subject fusion proteins find use in the preparation of a variety of nanostructures, where such structures include: cages, shells, double-layer rings, two-dimensional layers, three-dimensional crystals, filaments, and tubes.

  9. Consensus protein design.

    PubMed

    Porebski, Benjamin T; Buckle, Ashley M

    2016-07-01

    A popular and successful strategy in semi-rational design of protein stability is the use of evolutionary information encapsulated in homologous protein sequences. Consensus design is based on the hypothesis that at a given position, the respective consensus amino acid contributes more than average to the stability of the protein than non-conserved amino acids. Here, we review the consensus design approach, its theoretical underpinnings, successes, limitations and challenges, as well as providing a detailed guide to its application in protein engineering. PMID:27274091

  10. Prediction of protein-protein interactions based on protein-protein correlation using least squares regression.

    PubMed

    Huang, De-Shuang; Zhang, Lei; Han, Kyungsook; Deng, Suping; Yang, Kai; Zhang, Hongbo

    2014-01-01

    In order to transform protein sequences into the feature vectors, several works have been done, such as computing auto covariance (AC), conjoint triad (CT), local descriptor (LD), moran autocorrelation (MA), normalized moreaubroto autocorrelation (NMB) and so on. In this paper, we shall adopt these transformation methods to encode the proteins, respectively, where AC, CT, LD, MA and NMB are all represented by '+' in a unified manner. A new method, i.e. the combination of least squares regression with '+' (abbreviated as LSR(+)), will be introduced for encoding a protein-protein correlation-based feature representation and an interacting protein pair. Thus there are totally five different combinations for LSR(+), i.e. LSRAC, LSRCT, LSRLD, LSRMA and LSRNMB. As a result, we combined a support vector machine (SVM) approach with LSR(+) to predict protein-protein interactions (PPI) and PPI networks. The proposed method has been applied on four datasets, i.e. Saaccharomyces cerevisiae, Escherichia coli, Homo sapiens and Caenorhabditis elegans. The experimental results demonstrate that all LSR(+) methods outperform many existing representative algorithms. Therefore, LSR(+) is a powerful tool to characterize the protein-protein correlations and to infer PPI, whilst keeping high performance on prediction of PPI networks. PMID:25059329

  11. Human Mitochondrial Protein Database

    National Institute of Standards and Technology Data Gateway

    SRD 131 Human Mitochondrial Protein Database (Web, free access)   The Human Mitochondrial Protein Database (HMPDb) provides comprehensive data on mitochondrial and human nuclear encoded proteins involved in mitochondrial biogenesis and function. This database consolidates information from SwissProt, LocusLink, Protein Data Bank (PDB), GenBank, Genome Database (GDB), Online Mendelian Inheritance in Man (OMIM), Human Mitochondrial Genome Database (mtDB), MITOMAP, Neuromuscular Disease Center and Human 2-D PAGE Databases. This database is intended as a tool not only to aid in studying the mitochondrion but in studying the associated diseases.

  12. PIC: Protein Interactions Calculator.

    PubMed

    Tina, K G; Bhadra, R; Srinivasan, N

    2007-07-01

    Interactions within a protein structure and interactions between proteins in an assembly are essential considerations in understanding molecular basis of stability and functions of proteins and their complexes. There are several weak and strong interactions that render stability to a protein structure or an assembly. Protein Interactions Calculator (PIC) is a server which, given the coordinate set of 3D structure of a protein or an assembly, computes various interactions such as disulphide bonds, interactions between hydrophobic residues, ionic interactions, hydrogen bonds, aromatic-aromatic interactions, aromatic-sulphur interactions and cation-pi interactions within a protein or between proteins in a complex. Interactions are calculated on the basis of standard, published criteria. The identified interactions between residues can be visualized using a RasMol and Jmol interface. The advantage with PIC server is the easy availability of inter-residue interaction calculations in a single site. It also determines the accessible surface area and residue-depth, which is the distance of a residue from the surface of the protein. User can also recognize specific kind of interactions, such as apolar-apolar residue interactions or ionic interactions, that are formed between buried or exposed residues or near the surface or deep inside. PMID:17584791

  13. Glycolipid transfer proteins

    PubMed Central

    Brown, Rhoderick E.; Mattjus, Peter

    2007-01-01

    Glycolipid transfer proteins (GLTPs) are small (24 kD), soluble, ubiquitous proteins characterized by their ability to accelerate the intermembrane transfer of glycolipids in vitro. GLTP specificity encompasses both sphingoid- and glycerol-based glycolipids, but with a strict requirement that the initial sugar residue be beta-linked to the hydrophobic lipid backbone. The 3D protein structures of GLTP reveal liganded structures with unique lipid binding modes. The biochemical properties of GLTP action at the membrane surface have been studied rather comprehensively, but the biological role of GLTP remains enigmatic. What is clear is that GLTP differs distinctly from other known glycolipid-binding proteins, such as nonspecific lipid transfer proteins, lysosomal sphingolipid activator proteins, lectins, lung surfactant proteins as well as other lipid binding/transfer proteins. Based on the unique conformational architecture that targets GLTP to membranes and enables glycolipid binding, GLTP is now considered the prototypical and founding member of a new protein superfamily in eukaryotes. PMID:17320476

  14. Engineering therapeutic protein disaggregases.

    PubMed

    Shorter, James

    2016-05-15

    Therapeutic agents are urgently required to cure several common and fatal neurodegenerative disorders caused by protein misfolding and aggregation, including amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), and Alzheimer's disease (AD). Protein disaggregases that reverse protein misfolding and restore proteins to native structure, function, and localization could mitigate neurodegeneration by simultaneously reversing 1) any toxic gain of function of the misfolded form and 2) any loss of function due to misfolding. Potentiated variants of Hsp104, a hexameric AAA+ ATPase and protein disaggregase from yeast, have been engineered to robustly disaggregate misfolded proteins connected with ALS (e.g., TDP-43 and FUS) and PD (e.g., α-synuclein). However, Hsp104 has no metazoan homologue. Metazoa possess protein disaggregase systems distinct from Hsp104, including Hsp110, Hsp70, and Hsp40, as well as HtrA1, which might be harnessed to reverse deleterious protein misfolding. Nevertheless, vicissitudes of aging, environment, or genetics conspire to negate these disaggregase systems in neurodegenerative disease. Thus, engineering potentiated human protein disaggregases or isolating small-molecule enhancers of their activity could yield transformative therapeutics for ALS, PD, and AD. PMID:27255695

  15. Cellulose synthase interacting protein

    PubMed Central

    Somerville, Chris

    2010-01-01

    Cellulose is the most abundant biopolymer on earth. The great abundance of cellulose places it at the forefront as a primary source of biomass for renewable biofuels. However, the knowledge of how plant cells make cellulose remains very rudimentary. Cellulose microfibrils are synthesized at the plasma membrane by hexameric protein complexes, also known as cellulose synthase complexes. The only known components of cellulose synthase complexes are cellulose synthase (CESA) proteins until the recent identification of a novel component. CSI1, which encodes CESA interacting protein 1 (CSI1) in Arabidopsis. CSI1, as the first non-CESA proteins associated with cellulose synthase complexes, opens up many opportunities. PMID:21150290

  16. Consensus protein design

    PubMed Central

    Porebski, Benjamin T.; Buckle, Ashley M.

    2016-01-01

    A popular and successful strategy in semi-rational design of protein stability is the use of evolutionary information encapsulated in homologous protein sequences. Consensus design is based on the hypothesis that at a given position, the respective consensus amino acid contributes more than average to the stability of the protein than non-conserved amino acids. Here, we review the consensus design approach, its theoretical underpinnings, successes, limitations and challenges, as well as providing a detailed guide to its application in protein engineering. PMID:27274091

  17. Acanthamoeba castellanii STAT protein.

    PubMed

    Kicinska, Anna; Leluk, Jacek; Jarmuszkiewicz, Wieslawa

    2014-01-01

    STAT (signal transducers and activators of transcription) proteins are one of the important mediators of phosphotyrosine-regulated signaling in metazoan cells. We described the presence of STAT protein in a unicellular, free-living amoebae with a simple life cycle, Acanthamoeba castellanii. A. castellanii is the only, studied to date, Amoebozoan that does not belong to Mycetozoa but possesses STATs. A sequence of the A. castellanii STAT protein includes domains similar to those of the Dictyostelium STAT proteins: a coiled coil (characteristic for Dictyostelium STAT coiled coil), a STAT DNA-binding domain and a Src-homology domain. The search for protein sequences homologous to A. castellanii STAT revealed 17 additional sequences from lower eukaryotes. Interestingly, all of these sequences come from Amoebozoa organisms that belong to either Mycetozoa (slime molds) or Centramoebida. We showed that there are four separated clades within the slime mold STAT proteins. The A. castellanii STAT protein branches next to a group of STATc proteins from Mycetozoa. We also demonstrate that Amoebozoa form a distinct monophyletic lineage within the STAT protein world that is well separated from the other groups. PMID:25338074

  18. Engineering therapeutic protein disaggregases

    PubMed Central

    Shorter, James

    2016-01-01

    Therapeutic agents are urgently required to cure several common and fatal neurodegenerative disorders caused by protein misfolding and aggregation, including amyotrophic lateral sclerosis (ALS), Parkinson’s disease (PD), and Alzheimer’s disease (AD). Protein disaggregases that reverse protein misfolding and restore proteins to native structure, function, and localization could mitigate neurodegeneration by simultaneously reversing 1) any toxic gain of function of the misfolded form and 2) any loss of function due to misfolding. Potentiated variants of Hsp104, a hexameric AAA+ ATPase and protein disaggregase from yeast, have been engineered to robustly disaggregate misfolded proteins connected with ALS (e.g., TDP-43 and FUS) and PD (e.g., α-synuclein). However, Hsp104 has no metazoan homologue. Metazoa possess protein disaggregase systems distinct from Hsp104, including Hsp110, Hsp70, and Hsp40, as well as HtrA1, which might be harnessed to reverse deleterious protein misfolding. Nevertheless, vicissitudes of aging, environment, or genetics conspire to negate these disaggregase systems in neurodegenerative disease. Thus, engineering potentiated human protein disaggregases or isolating small-molecule enhancers of their activity could yield transformative therapeutics for ALS, PD, and AD. PMID:27255695

  19. Ultrafiltration of pegylated proteins

    NASA Astrophysics Data System (ADS)

    Molek, Jessica R.

    There is considerable clinical interest in the use of "second-generation" therapeutics produced by conjugation of a native protein with various polymers including polyethylene glycol (PEG). PEG--protein conjugates, so-called PEGylated proteins, can exhibit enhanced stability, half-life, and bioavailability. One of the challenges in the commercial production of PEGylated proteins is the purification required to remove unreacted polymer, native protein, and in many cases PEGylated proteins with nonoptimal degrees of conjugation. The overall objective of this thesis was to examine the use of ultrafiltration for the purification of PEGylated proteins. This included: (1) analysis of size-based separation of PEGylated proteins using conventional ultrafiltration membranes, (2) use of electrically-charged membranes to exploit differences in electrostatic interactions, and (3) examination of the effects of PEGylation on protein fouling. The experimental results were analyzed using appropriate theoretical models, with the underlying physical properties of the PEGylated proteins evaluated using size exclusion chromatography, capillary electrophoresis, dynamic light scattering, and reverse phase chromatography. PEGylated proteins were produced by covalent attachment of activated PEG to a protein via primary amines on the lysine residues. A simple model was developed for the reaction kinetics, which was used to explore the effect of reaction conditions and mode of operation on the distribution of PEGylated products. The effective size of the PEGylated proteins was evaluated using size exclusion chromatography, with appropriate correlations developed for the size in terms of the molecular weight of the native protein and attached PEG. The electrophoretic mobility of the PEGylated proteins were evaluated by capillary electrophoresis with the data in good agreement with a simple model accounting for the increase in protein size and the reduction in the number of protonated amine

  20. Protein metabolism and requirements.

    PubMed

    Biolo, Gianni

    2013-01-01

    Skeletal muscle adaptation to critical il