Academic literature on the topic 'TOS actif'
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Journal articles on the topic "TOS actif"
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Bryce, Nicole S., Galina Schevzov, Vicki Ferguson, Justin M. Percival, Jim J. C. Lin, Fumio Matsumura, James R. Bamburg, et al. "Specification of Actin Filament Function and Molecular Composition by Tropomyosin Isoforms." Molecular Biology of the Cell 14, no. 3 (March 2003): 1002–16. http://dx.doi.org/10.1091/mbc.e02-04-0244.
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The specific functions of greater than 40 vertebrate nonmuscle tropomyosins (Tms) are poorly understood. In this article we have tested the ability of two Tm isoforms, TmBr3 and the human homologue of Tm5 (hTM5NM1), to regulate actin filament function. We found that these Tms can differentially alter actin filament organization, cell size, and shape. hTm5NM1was able to recruit myosin II into stress fibers, which resulted in decreased lamellipodia and cellular migration. In contrast, TmBr3 transfection induced lamellipodial formation, increased cellular migration, and reduced stress fibers. Based on coimmunoprecipitation and colocalization studies, TmBr3 appeared to be associated with actin-depolymerizing factor/cofilin (ADF)-bound actin filaments. Additionally, the Tms can specifically regulate the incorporation of other Tms into actin filaments, suggesting that selective dimerization may also be involved in the control of actin filament organization. We conclude that Tm isoforms can be used to specify the functional properties and molecular composition of actin filaments and that spatial segregation of isoforms may lead to localized specialization of actin filament function.
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Bridge, Dacie R., Karen H. Martin, Elizabeth R. Moore, Wendy M. Lee, James A. Carroll, Claudia L. Rocha, and Joan C. Olson. "Examining the Role of Actin-Plasma Membrane Association in Pseudomonas aeruginosa Infection and Type III Secretion Translocation in Migratory T24 Epithelial Cells." Infection and Immunity 80, no. 9 (June 11, 2012): 3049–64. http://dx.doi.org/10.1128/iai.00231-12.
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ABSTRACTThe opportunistic pathogenPseudomonas aeruginosatargets wounded epithelial barriers, but the cellular alteration that increases susceptibility toP. aeruginosainfection remains unclear. This study examined how cell migration contributes to the establishment ofP. aeruginosainfections using (i) highly migratory T24 epithelial cells as a cell culture model, (ii) mutations in the type III secretion (T3S) effector ExoS to manipulateP. aeruginosainfection, and (iii) high-resolution immunofluorescent microscopy to monitor ExoS translocation. ExoS includes both GTPase-activating (GAP) and ADP-ribosyltransferase (ADPRT) activities, andP. aeruginosacells expressing wild-type ExoS preferentially bound to the leading edge of T24 cells, where ExoS altered leading-edge architecture and actin anchoring in conjunction with interrupting T3S translocation. Inactivation of ExoS GAP activity allowedP. aeruginosato be internalized and secrete ExoS within T24 cells, but as with wild-type ExoS, translocation was limited in association with disruption of actin anchoring. Inactivation of ExoS ADPRT activity resulted in significantly enhanced T3S translocation byP. aeruginosacells that remained extracellular and in conjunction with maintenance of actin-plasma membrane association. Infection withP. aeruginosaexpressing ExoS lacking both GAP and ADPRT activities resulted in the highest level of T3S translocation, and this occurred in conjunction with the entry and alignment ofP. aeruginosaand ExoS along actin filaments. Collectively, in using ExoS mutants to modulate and visualize T3S translocation, we were able to (i) confirm effector secretion by internalizedP. aeruginosa, (ii) differentiate the mechanisms underlying the effects of ExoS GAP and ADPRT activities onP. aeruginosainternalization and T3S translocation, (iii) confirm that ExoS ADPRT activity targeted a cellular substrate that interrupted T3S translocation, (iv) visualize the ability ofP. aeruginosaand ExoS to align with actin filaments, and (v) demonstrate an association between actin anchoring at the leading edge of T24 cells and the establishment ofP. aeruginosainfection. Our studies also highlight the contribution of ExoS to the opportunistic nature ofP. aeruginosainfection through its ability to exert cytotoxic effects that interrupt T3S translocation andP. aeruginosainternalization, which in turn limit theP. aeruginosainfectious process.
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Ivanov, Andrei I., Dirk Hunt, Markus Utech, Asma Nusrat, and Charles A. Parkos. "Differential Roles for Actin Polymerization and a Myosin II Motor in Assembly of the Epithelial Apical Junctional Complex." Molecular Biology of the Cell 16, no. 6 (June 2005): 2636–50. http://dx.doi.org/10.1091/mbc.e05-01-0043.
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Differentiation and polarization of epithelial cells depends on the formation of the apical junctional complex (AJC), which is composed of the tight junction (TJ) and the adherens junction (AJ). In this study, we investigated mechanisms of actin reorganization that drive the establishment of AJC. Using a calcium switch model, we observed that formation of the AJC in T84 intestinal epithelial cells began with the assembly of adherens-like junctions followed by the formation of TJs. Early adherens-like junctions and TJs readily incorporated exogenous G-actin and were disassembled by latrunculin B, thus indicating dependence on continuous actin polymerization. Both adherens-like junctions and TJs were enriched in actin-related protein 3 and neuronal Wiskott-Aldrich syndrome protein (N-WASP), and their assembly was prevented by the N-WASP inhibitor wiskostatin. In contrast, the formation of TJs, but not adherens-like junctions, was accompanied by recruitment of myosin II and was blocked by inhibition of myosin II with blebbistatin. In addition, blebbistatin inhibited the ability of epithelial cells to establish a columnar phenotype with proper apico-basal polarity. These findings suggest that actin polymerization directly mediates recruitment and maintenance of AJ/TJ proteins at intercellular contacts, whereas myosin II regulates cell polarization and correct positioning of the AJC within the plasma membrane.
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Pittenger, M. F., A. Kistler, and D. M. Helfman. "Alternatively spliced exons of the beta tropomyosin gene exhibit different affinities for F-actin and effects with nonmuscle caldesmon." Journal of Cell Science 108, no. 10 (October 1, 1995): 3253–65. http://dx.doi.org/10.1242/jcs.108.10.3253.
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The rat beta-tropomyosin (TM) gene expresses two isoforms via alternative RNA splicing, namely skeletal muscle beta-TM and fibroblast TM-1. The latter is also expressed in smooth muscle where it corresponds to smooth muscle beta-TM. Skeletal muscle beta-TM contains exons 7 and 10, whereas exons 6 and 11 are used in fibroblasts and smooth muscle. In order to study the properties of the alternatively spliced proteins, recombinant TMs derived from bacterial and insect cell expression systems were produced, including the normal beta gene products, fibroblast TM-1 and beta skeletal muscle TM, two carboxy-terminal chimeric TMs, TM-6/10 and TM-7/11, as well as a carboxyl-truncated version of each, TM-6Cla and TM-7Cla. The purified TM isoforms were used in actin filament association studies. The apparent TM association constants (Ka) were taken as the free concentration at half saturation and were found to be 6 microM for beta Sk TM, 8.5 for TM-6/10, 25 microM for TM-1, and 30 microM for TM-7/11 at an F-actin concentration of 42 microM. For the truncated TMs, the values determined were higher still but the binding was not carried out to full saturation. Isoforms were also produced using the baculovirus-insect cell system which produces proteins with an acetylated amino terminus as is normally found in vivo. This modification significantly enhanced the F-actin association of TM-1 but not the beta skeletal TM or the other isoforms. Fibroblast TM-2 or TM-3, both products of the alpha gene, enhanced the affinity of TM-1 for F-actin, demonstrating different isoforms can act cooperatively on binding to actin. This effect was not detected with the other expressed beta gene products. The presence of 83 kDa nonmuscle caldesmon was found to enhance the binding of TM-1 for F-actin. This effect was dependent on the presence of both exons 6 and 11, as caldesmon had little effect on the other beta gene products. Collectively these results demonstrate TMs differ in their affinity for F-actin, which can be altered by other TMs or actin-binding proteins. The beta tropomyosin isoforms were fluorescently-tagged and microinjected into cultured cells to study their in vivo localization where it was found that each of the full-length TMs bound to microfilaments but, at the light microscopy level, the isoforms were not differentially localized in these fibroblasts.
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ROTTER, Björn, Odile BOURNIER, Gael NICOLAS, Didier DHERMY, and Marie-Christine LECOMTE. "αII-Spectrin interacts with Tes and EVL, two actin-binding proteins located at cell contacts." Biochemical Journal 388, no. 2 (May 24, 2005): 631–38. http://dx.doi.org/10.1042/bj20041502.
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The spectrin-based membrane skeleton, a multi-protein scaffold attached to diverse cellular membranes, is presumed to be involved in the stabilization of membranes, the establishment of membrane domains as well as in vesicle trafficking and nuclear functions. Spectrin tetramers made of α- and β-subunits are linked to actin microfilaments, forming a network that binds a multitude of proteins. The most prevalent α-spectrin subunit in non-erythroid cells, αII-spectrin, contains two particular spectrin repeats in its central region, α9 and α10, which host an Src homology 3 domain, a tissue-specific spliced sequence of 20 residues, a calmodulin-binding site and major cleavage sites for caspases and calpains. Using yeast two-hybrid screening of kidney libraries, we identified two partners of the α9-α10 repeats: the potential tumour suppressor Tes, an actin-binding protein mainly located at focal adhesions; and EVL (Ena/vasodilator-stimulated phosphoprotein-like protein), another actin-binding protein, equally recruited at focal adhesions. Interactions between spectrin and overexpressed Tes and EVL were confirmed by co-immunoprecipitation. In vitro studies showed that the interaction between Tes and spectrin is mediated by a LIM (Lin-11, Isl-1 and Mec3) domain of Tes and by the α10 repeat of αII-spectrin whereas EVL interacts with the Src homology 3 domain located within the α9 repeat. Moreover, we describe an in vitro interaction between Tes and EVL, and a co-localization of these two proteins at focal adhesions. These interactions between αII-spectrin, Tes and EVL indicate new functions for spectrin in actin dynamics and focal adhesions.
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Bridge, Dacie R., Matthew J. Novotny, Elizabeth R. Moore, and Joan C. Olson. "Role of host cell polarity and leading edge properties in Pseudomonas type III secretion." Microbiology 156, no. 2 (February 1, 2010): 356–73. http://dx.doi.org/10.1099/mic.0.033241-0.
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Type III secretion (T3S) functions in establishing infections in a large number of Gram-negative bacteria, yet little is known about how host cell properties might function in this process. We used the opportunistic pathogen Pseudomonas aeruginosa and the ability to alter host cell sensitivity to Pseudomonas T3S to explore this problem. HT-29 epithelial cells were used to study cellular changes associated with loss of T3S sensitivity, which could be induced by treatment with methyl-beta-cyclodextrin or perfringolysin O. HL-60 promyelocytic cells are innately resistant to Pseudomonas T3S and were used to study cellular changes occurring in response to induction of T3S sensitivity, which occurred following treatment with phorbol esters. Using both cell models, a positive correlation was observed between eukaryotic cell adherence to tissue culture wells and T3S sensitivity. In examining the type of adhesion process linked to T3S sensitivity in HT-29 cells, a hierarchical order of protein involvement was identified that paralleled the architecture of leading edge (LE) focal complexes. Conversely, in HL-60 cells, induction of T3S sensitivity coincided with the onset of LE properties and the development of actin-rich projections associated with polarized cell migration. When LE architecture was examined by immunofluorescent staining for actin, Rac1, IQ-motif-containing GTPase-activating protein 1 (IQGAP1) and phosphatidylinositol 3 kinase (PI3 kinase), intact LE structure was found to closely correlate with host cell sensitivity to P. aeruginosa T3S. Our model for host cell involvement in Pseudomonas T3S proposes that cortical actin polymerization at the LE alters membrane properties to favour T3S translocon function and the establishment of infections, which is consistent with Pseudomonas infections targeting wounded epithelial barriers undergoing cell migration.
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Jin, Sun Woo, Gi Ho Lee, Hoa Thi Pham, Jae Ho Choi, and Hye Gwang Jeong. "Polyhexamethylene Guanidine Phosphate Damages Tight Junctions and the F-Actin Architecture by Activating Calpain-1 via the P2RX7/Ca2+ Signaling Pathway." Cells 9, no. 1 (December 24, 2019): 59. http://dx.doi.org/10.3390/cells9010059.
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Polyhexamethylene guanidine phosphate (PHMG-p), a member of the polymeric guanidine family, has strong antimicrobial activity and may increase the risk of inflammation-associated pulmonary fibrosis. However, the effect of PHMG-p on the barrier function of the bronchial epithelium is unknown. Epithelial barrier functioning is maintained by tight junctions (TJs); damage to these TJs is the major cause of epithelial barrier breakdown during lung inflammation. The present study showed that, in BEAS-2B human bronchial epithelial cells, exposure to PHMG-p reduced the number of TJs and the E-cadherin level and impaired the integrity of the F-actin architecture. Furthermore, exposure to PHMG-p stimulated the calcium-dependent protease calpain-1, which breaks down TJs. However, treatment with the calpain-1 inhibitor, ALLN, reversed the PHMG-p-mediated impairment of TJs and the F-actin architecture. Furthermore, exposure to PHMG-p increased the intracellular Ca2+ level via P2X purinoreceptor 7 (P2RX7) and inhibition of P2RX7 abolished the PHMG-p-induced calpain-1 activity and protein degradation and increased the intracellular Ca2+ level. Although exposure to PHMG-p increased the extracellular ATP level, hydrolysis of extracellular ATP by apyrase did not influence its detrimental effect on bronchial epithelial cells. These results implicate the impairment of TJs and the F-actin architecture in the pathogenesis of pulmonary diseases.
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Garvalov, Boyan K., Theresa E. Higgins, James D. Sutherland, Markus Zettl, Niki Scaplehorn, Thomas Köcher, Eugenia Piddini, Gareth Griffiths, and Michael Way. "The conformational state of Tes regulates its zyxin-dependent recruitment to focal adhesions." Journal of Cell Biology 161, no. 1 (April 14, 2003): 33–39. http://dx.doi.org/10.1083/jcb.200211015.
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The function of the human Tes protein, which has extensive similarity to zyxin in both sequence and domain organization, is currently unknown. We now show that Tes is a component of focal adhesions that, when expressed, negatively regulates proliferation of T47D breast carcinoma cells. Coimmunoprecipitations demonstrate that in vivo Tes is complexed with actin, Mena, and vasodilator-stimulated phosphoprotein (VASP). Interestingly, the isolated NH2-terminal half of Tes pulls out α-actinin and paxillin from cell extracts in addition to actin. The COOH-terminal half recruits zyxin as well as Mena and VASP from cell extracts. These differences suggest that the ability of Tes to associate with α-actinin, paxillin, and zyxin is dependent on the conformational state of the molecule. Consistent with this hypothesis, we demonstrate that the two halves of Tes interact with each other in vitro and in vivo. Using fibroblasts lacking Mena and VASP, we show that these proteins are not required to recruit Tes to focal adhesions. However, using RNAi ablation, we demonstrate that zyxin is required to recruit Tes, as well as Mena and VASP, but not vinculin or paxillin, to focal adhesions.
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Pittenger, M. F., and D. M. Helfman. "In vitro and in vivo characterization of four fibroblast tropomyosins produced in bacteria: TM-2, TM-3, TM-5a, and TM-5b are co-localized in interphase fibroblasts." Journal of Cell Biology 118, no. 4 (August 15, 1992): 841–58. http://dx.doi.org/10.1083/jcb.118.4.841.
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Most cell types express several tropomyosin isoforms, the individual functions of which are poorly understood. In rat fibroblasts there are at least six isoforms; TM-1, TM-2, TM-3, TM-4, TM-5a, and TM-5b. TM-1 is the product of the beta gene. TM-4 is produced from the TM-4 gene, and TMs 2, 3, 5a, and 5b are the products of the alpha gene. To begin to study the localization and function of the isoforms in fibroblasts, cDNAs for TM isoforms 2, 3, 5a, and 5b were placed into bacterial expression vectors and used to produce TM isoforms. The bacterially produced TMs were determined to be full length by sequencing the amino- and carboxy termini. These TMs were found to bind to F-actin in vitro, with properties similar to that of skeletal muscle TM. In addition, competition experiments demonstrated that TM-5b was better than TM-5a in displacing other TM isoforms from F-actin in vitro. To investigate the intracellular localization of these fibroblast isoforms, each was derivatized with a fluorescent chromophore and microinjected into rat fibroblasts. TM-2, TM-3, TM-5a, and TM-5b were each found to associate along actin filaments. There was no preferred cellular location or subset of actin filaments for these isoforms. Furthermore, co-injection of two isoforms labeled with different fluorochromes showed identical staining. At the level of the light microscope, these isoforms from the alpha gene do not appear to achieve different functions by binding to particular subsets of actin filaments or locations in cells. Some alternative possibilities are discussed. The results show that bacterially produced TMs can be used to study in vitro and in vivo properties of the isoforms.
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Terai, Tomoya, Noriyuki Nishimura, Ikuno Kanda, Natsuo Yasui, and Takuya Sasaki. "JRAB/MICAL-L2 Is a Junctional Rab13-binding Protein Mediating the Endocytic Recycling of Occludin." Molecular Biology of the Cell 17, no. 5 (May 2006): 2465–75. http://dx.doi.org/10.1091/mbc.e05-09-0826.
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The dynamic turnover of tight junctions (TJs) is essential for epithelial-mesenchymal transitions and/or mesenchymal-epithelial transitions during epithelial morphogenesis. We previously demonstrated that Rab13 specifically mediates the endocytic recycling of occludin. Here, we identified MICAL-L2 (molecule interacting with CasL-like 2) as a novel Rab13-binding protein. Immunoprecipitation and immunofluorescence microscopy showed that MICAL-L2 specifically bound to the GTP-bound form of Rab13 via its C terminus, which contained a coiled-coil domain, and localized at TJs in epithelial MTD-1A cells. Recycling assay demonstrated that a MICAL-L2 mutant lacking the Rab13-binding domain (MICAL-L2-N) specifically inhibited the endocytic recycling of occludin but not transferrin receptor. Ca2+ switch assay further revealed that MICAL-L2-N as well as Rab13 Q67L inhibited the recruitment of occludin to the plasma membrane, the development of transepithelial electrical resistance, and the formation of a paracellular diffusion barrier. MICAL-L2 was displaced from TJs upon actin depolymerization and was distributed along radiating actin cables and stress fibers in Ca2+-depleted MTD-1A and fibroblastic NIH3T3 cells, respectively. These results suggest that MICAL-L2 mediates the endocytic recycling of occludin and the formation of functional TJs by linking Rab13 to actin cytoskeleton. We rename MICAL-L2 as JRAB (junctional Rab13-binding protein).
Dissertations / Theses on the topic "TOS actif"
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Coquillas, Benjamin. "Nouvelles topologies d’amplificateurs de puissance SiGe en bande Ku, optimisées en puissance, rendement et robustes au TOS actif." Thesis, Bordeaux, 2022. http://www.theses.fr/2022BORD0173.
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L’amélioration des systèmes RADAR des aéronefs actuels est confrontée aux deux défis majeurs que sont la réduction des surfaces occupées et la maîtrise du coût. Ces défis s’ajoutent aux contraintes matérielles spécifiques des missiles autodirecteurs concernant la tenue en puissance à forte température et la robustesse aux variations de charge extérieure causées par le dépointage des éléments rayonnants environnants (apparentées au phénomène de TOS actif). Un enjeu majeur réside dans la réponse de l’amplificateur de puissance, identifié comme brique élémentaire, à ces défis actuels. La technologie Silicium Germanium (SiGe) est mise en avant par de nombreux travaux académiques sur les nouvelles générations de télécommunication (5G, 6G). Des travaux récents sur des amplificateurs de puissance publiés entre 2016 et 2020 apportent des résultats proches des caractéristiques souhaitées sur des bandes de fréquence bande X et la partie basse de la bande Ku. Ce double contexte industriel et académique justifie une étude originale sur les caractéristiques et les limites de la technologie SiGe en haut de la bande Ku au regard de la puissance de sortie, du rendement, de la robustesse au TOS actif et de la tenue des performances en température. Au cours de ces travaux, avec à l’appui une étude bibliographique documentée et un cahier des charges précis, cinq motifs de puissance et trois types de coupleur sont réalisés, simulés, envoyés en fabrication et mesurés. La topologie d’architecture équilibrée, mise en exergue sur de nombreuses études relatives au self-contained, constitue notamment un pilier central de cette étude. Les choix de conception et les performances obtenues sont détaillés. Ces dernières sont comparées à l’état de l’art. Elles démontrent des avancées significatrices valorisées dans trois conférences majeures du domaine scientifique et apportent des réponses originales aux défis contemporains de conception d’amplificateurs de puissance pour une application RADAR au sein de missiles autodirecteursThe improvement of the RADAR systems of the current aircraft is confronted with the two major challenges of the reduction of the areas occupied and the control of the cost. These challenges are added to the specific material constraints of self-guided missiles concerning power handling at high temperature and robustness to external load variations caused by the misalignment of surrounding radiating elements (related to the active SWR phenomenon). A major challenge is based on the response of the power amplifier, identified as an elementary building block, to these current challenges. The Silicon Germanium (SiGe) technology is highlighted by many academic works on new generations of telecommunications (5G, 6G). Several recent works on power amplifiers published between 2016 and 2020 bring results close to the desired characteristics on X-band and low Ku-band. This dual industrial and academic context justifies an original study on the characteristics and limits of the SiGe technology at the top of the Ku band with regard to the output power, efficiency, robustness to active SWR and the power handling to temperature variations. During this work, with the support of a documented bibliographical study and acurrate specifications, five power patterns and three types of coupler are designed, simulated, sent to manufacturing and measured. The balanced architecture topology, highlighted in several self contained studies, is a central pillar of this study. The design choices and the performances obtained are detailed. These are compared to the state of the art. They demonstrate significant advances valued in three major conferences in the scientific field and provide original answers to the contemporary challenges of designing power amplifiers for a RADAR application within self-guided missiles
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Flores, Moralest Areli. "Extaction liquide-liquide d'acides polycarboxyliques : influence de l'extactant (TBP et TOA) et des diluants actif et inerte." Toulouse, INPT, 2003. http://www.theses.fr/2003INPT006G.
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Dans les industries chimiques, pharmaceutiques, alimentaires et biotechnologiques il existe de nombreux exemples où il est nécessaire d'extraire des acides des effluents aqueux ou des jus de fermentation. L'extraction liquide-liquide est une technique de séparation intéressante qui a de nombreuses applications dans l'industrie. L'extraction réactive est utilisée pour la récupération et la purification d'acides carboxyliques avec des extractants comme les composés organophosphorés et les amines aliphatiques de masse moléculaire élevée. Les extractants sont mélangés avec différents types de diluants qui peuvent influencer la distribution de composés entre les 2 phases à l'équilibre. Pour récupérer et séparer les acides organiques il est important de connaître l'influence des facteurs qui gouvernent l'équilibre. Ainsi, pour étudier le mécanisme il est nécessaire de connaître la constante d'extraction et le nombre de molécules d'extractant qui réagissent avec une molécule d'acide. Pour cela on applique généralement la loi d'action de masse. Dans ce travail nous avons étudié l'extraction de 14 acides carboxyliques par le TBP et la TOA mélangés dans le dodécane et le décanol. Nous avons déterminé le coefficient de distribution, le nombre de complexation et la constante d'extraction ainsi que l'influence de la structure moléculaire sur ces 3 paramètres. Le modèle qui représente le mécanisme d'extraction de ces acides permet d'appréhender l'influence du diluant. Les valeurs du nombre de complexation dépendent des conditions opératoires notamment de la concentration initiale en acide, du pH et du taux de solvant. En définitive ce travail ouvre de bonnes perpectives pour évaluer l'efficacité et optimiser un procédé d'extraction et de récupération d'acides organiques.
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Gillet, Vincent. "Développement d'un banc de load-pull actif innovant, utilisant un signal multi-tons large bande pour la mesure de la linéarité (EVM, NPR, ACPR) des dispositifs actifs." Thesis, Limoges, 2019. http://www.theses.fr/2019LIMO0114.
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Cette thèse présente l’utilisation innovante du signal Unequally Spaced Multi-Tones (USMT) dans la mesure de linéarité des transmetteurs de télécommunications (5G). Ce signal offre une nouvelle perspective permettant la caractérisation des formes d’ondes réelles en utilisant un signal avec un nombre de tons très réduit, se comportant comme une extension de la caractérisation 2-tons. Ce signal est simple à mettre en oeuvre, à mesurer et à analyser. Il nécessite des moyens peu onéreux, (générateur de signaux arbitraires, analyseur de spectre). Il peut s’utiliser à différent niveau de l’industrie : de la fabrication (wafer) jusqu’à la ligne de production, en passant par les transistors packagés. Cette thèse a démontré la faisabilité d’un banc automatique de mesures multi-tons, utilisant ce signal USMT, pour la caractérisation load-pull (passif et actif ) de transmetteurs de télécommunications. La maîtrise de cette technique de mesure des non-linéarités représente un avantage concurrentiel à tous les niveaux de la conception du front-end radio fréquence et un gain financier indéniableThis manuscript describes an innovative use of the Unequally Spaced Multi-Tones test signal to achieve linearity characterization of telecommunication transmitter (5G). This signal offers new perspectives of characterization using real waveform involving a reduce number of tone test signal, which in turn behaves as an extension of the 2- tone characterization. This innovative test signal is easy to generate, to measure and to analyze. It required not particular expensive hardware to be generated (arbitrary waveform generator, spectrum analyzer). It is particularly interesting for production line testing, from on-wafer measurements up to radiofrequency front-end, passing through packaged transistor. This thesis demonstrated the feasability of automation of multitone measurement, using this particular USMT signal, for load-pull measurement (passive and active) of telecommunications transmitters. Managing this measurement technics represents a competitive advantage at all levels of the radio frequency front-end design and an undeniable financial gain
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Koppen, F. P. van. "Actio Pauliana en onrechtmatige daadvordering /." Deventer : Kluwer, 1998. http://www.gbv.de/dms/spk/sbb/recht/toc/272312657.pdf.
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Bejjani-Ghauch, Alice. "Apport de l’analyse élémentaire (IBA) et moléculaire (ToF-SIMS) par faisceaux d’ions à l’étude de matériaux d’intérêt environnemental et pharmaceutique." Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10302.
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Les faisceaux d’ions de l’ordre du MeV permettent la mise en œuvre de techniques d’analyse tant élémentaire (Ion Beam Analysis-IBA) que moléculaire (Time of Flight Secondary Ion Mass Spectrometry) pour des matériaux solides peu étudiés en raison de leur hétérogénéité: les mélanges de poudres. La première partie de notre travail est à placer dans le contexte de l’étude de la photodégradation des pesticides dans l’environnement à travers l’analyse ToF-SIMS de pesticides imprégnés dans des sols naturels. A partir d’une étude comparative du phénomène induit sur des dépôts sur des substrats homogènes nous présentons les résultats de la cinétique de dégradation pour plusieurs pesticides avec en particulier des valeurs de demi-vies. La seconde partie s’inscrit dans le processus de contrôle de produits pharmaceutiques commerciaux à analyser en l’état. Nous montrons que la quantification du principe actif (p.a.) en présence d’excipients est possible: -par les techniques IBA quand le p.a. contient des hétéroatomes non présents dans les excipients. La précision (<7%) est alors la plupart du temps bien meilleure que les exigences du contrôle industriel. -par la technique ToF-SIMS dans tous les cas mais dans des domaines définis par les courbes d’étalonnage pour avoir les meilleures sensibilités. Ces restrictions dépendent de la nature des partenaires (p.a. et excipients) et mettent en évidence des effets de matrice dont l’étude doit permettre l’amélioration de la préparation de tels échantillons en vue d’analyses plus performantes. Ces techniques dont les avantages et les limitations sont discutés, sont à notre connaissance utilisées pour la première fois sur de tels matériaux « réels »The aim of this study is to analyze heterogeneous organic matter by exhibiting analytical difficulties by classical techniques under solid state. The first part of this work is dedicated to the study of pesticides photodegradation impregnated in soils by ToF-SIMS technique. A comparative investigation of the induced phenomenon obtained with the same pesticides deposited as thin layer on a neutral support helped in studying the degradation kinetics of those pesticides especially their half-lives. The second part is dedicated to the development of new analytical method for the analysis of commercialized pharmaceutical compounds without prior sample preparation. We have demonstrated the possibility of active ingredient (A.I.) quantification in the presence of the excipients by the following analytical techniques: IBA techniques if the A.I. contains an heteroatom, however, absent in the excipients. The precision (< 7%) is found to be in the majority of the studied cases within the analytical standards of the quality control processes. ToF-SIMS technique for all drugs however within a specific range of concentration defined by the calibration curves for improved sensitivities. These restrictions in the dynamic concentration range depend on the nature of the mixtures A.I. / Excipients on hand and show evidence of the matrix effect on the other hand. A deep investigation on the matrix nature should improve the sample preparation method for more performance analysis. To our knowledge, it is the first time that the above mentioned techniques whose analytical advantages and limitations have been discussed were applied to such solid matrix samples
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Desbrosses, Mickaël. "Contribution de la Spectrométrie de Masse d’Ions Secondaires à Temps de Vol au développement de textiles industriels fonctionnels impliquant des agents actifs cosmétiques." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1117.
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La Spectrométrie de Masse d'Ions Secondaires à Temps de Vol (ToF-SIMS) permet la caractérisation de l'extrême surface à haute sensibilité via la détection d'ions secondaires atomiques et moléculaires. Ces travaux ont visé à étudier son application pour l'analyse de textiles industriels auxquels ont été conférées des propriétés dermatologiques (cosmétotextiles). Trois démarches analytiques adaptées aux spécificités des agents actifs et des technologies utilisées ont été présentées. Elles ont nécessité un développement particulier des méthodes employées (étude préliminaire, calibration, traitement et interprétation des données) et de tenir compte des possibilités et des limites de la technique ou de l'appareillage utilisé dans le contexte particulier de l'analyse des fibres textiles (topographie, effet de charge localisé, contaminations, formulations complexes, ségrégation et concentration de certains constituants des traitements en extrême surface).Dans la première démarche, la cartographie chimique ToF-SIMS a été utilisée avec succès pour illustrer l'existence d'un gradient de concentration en agent actif près de l'extrême surface de matrices polyamides. La capacité à identifier les signatures caractéristiques des agents actifs et valider leur présence en surface des échantillons textiles a pu être confirmée dans la majorité des cas. Cependant l'utilisation de signatures différentes de celles de l'agent actif a été nécessaire pour valider la présence de traitement dans le cas des textiles traités par co-précipitation. Enfin, un protocole de décapage doux a été testé pour faire face au problème particulier du recouvrement des textiles industriels par des apprêts siliconésTime-of-Flight Secondary Ion Mass spectrometry (ToF-SIMS) allows the characterization of the outermost surface with high sensitivity by mass detection of atomic and molecular secondary ions. The objective of this work was to study its application in the context of the analysis of industrial textiles on which dermatological properties are given (cosmetotextiles). Three analytical approaches based on the specific properties of the active agents and technologies are presented. They required peculiar developments of methods (preliminary study, calibration, data processing and interpretation ...) and to consider the possibilities and limitations of the technique or the equipment in the particular context of these textile fibers analysis (topography, localized charge effect, contamination, complex formulations, segregation and concentration of some components from the treatments at the outermost surface ...).In the first approach, ToF-SIMS chemical mapping was used to successfully illustrate an active agent concentration gradient close to the outermost surface of polyamide matrices. The ability to identify the characteristic signatures of active agents and to validate their presence at the surface of textile samples was confirmed in most cases. However, signatures different from those from the active agent were needed to validate the treatment in the case of textiles treated by co-precipitation. Finally, a gentle sputtering protocol was tested to address the particular issue of industrial textiles covered with silicone based textile finishing
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Tilstra, Liesbeth. "Grenzen aan het stakingsrecht : het Nederlandse rechtsoordeel over collectieve actie van werknemers getoetst aan het Europees Sociaal Handvest /." Deventer : Kluwer, 1994. http://www.gbv.de/dms/spk/sbb/recht/toc/272312207.pdf.
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Hubrich, Hanna. "Active Matter in Confined Geometries - Biophysics of Artificial Minimal Cortices." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-152A-5.
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Saniour, Isabelle. "Exploitation des effets électro-optiques pour la sécurité en IRM : applications des liaisons optiques pour des capteurs RF endoluminaux et des sondes de mesure du TAS." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1330/document.
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Le développement de systèmes IRM à plus haut champ magnétique statique s'est accompagné d'une interrogation légitime concernant l'effet des champs électromagnétiques RF sur les patients. L'effet peut être renforcé par l'introduction d'éléments conducteurs à l'intérieur de la bobine RF comme c'est le cas pour les capteurs endoluminaux utilisés pour l'analyse des parois digestives. Ces capteurs entraînent des risques d'échauffements locaux élevés pour le patient en raison du TAS local induit par le champ électrique RF en présence d'un fil conducteur. Ces capteurs ayant le potentiel de présenter un bénéfice pour le patient, il est nécessaire de s'affranchir de ces limitations. Le premier objectif de la thèse est le développement d'un capteur endoluminal à liaisons optiques. Un dispositif de découplage actif optique a été développé et caractérisé. Les images RMN in vitro montrent une distribution du RSB comparable au découplage classique, validant ainsi l'efficacité du découplage optique. Concernant la transmission optique du signal RMN, des travaux ont été réalisés afin de s'affranchir des contraintes liées à l'utilisation d'un guide d'onde pour la conversion électro-optique par effet Pockels. Le capteur a été rendu plus compact. En revanche, l'importance de contrôler le TAS local dans des conditions expérimentales données demeure un besoin ne s'arrêtant pas à ceux des capteurs endoluminaux. Le second objectif est donc la validation expérimentale d'une sonde électro-optique pour la mesure du champ électrique RF durant un examen IRM. Cette sonde a permis d'effectuer des mesures du champ électrique dans l'air et dans différents milieux biologiques à 3 T et 4,7 T et estimer le TAS localThe recent advancement in MRI systems and the increase of the static magnetic field strength were accompanied by a strong concern about the effect of RF electromagnetic fields on patients. The effect can be increased by the use of conductive elements inside the volume coil as in the case of endoluminal coils used to analyze digestive walls. These coils lead to an increase of the local SAR which is induced by RF electric field in the presence of the coaxial cable connecting the coil to the MR system, resulting in strong local heating. Giving that these coils have the potential to present a real benefit to the patient, it worth to overcome these limitations. Accordingly, the first objective of the thesis is the development of a fully optical endoluminal receiver coil. An optical active detuning system has been developed and characterized. The NMR images show a signal-to-noise ratio distribution similar to that obtained with conventional detuning techniques, thus validating the efficiency of the optical detuning. Concerning the electro-optical conversion and the optical transmission of the NMR signal, experiments were performed to overcome constraints related to the use of waveguide for electro-optical conversion by Pockels effect. Moreover, the importance of monitoring global and local SAR during MRI exams remains a need which is not limited only to the endoluminal coils. The second objective of the thesis is then the experimental validation of an electro-optical probe for real-time measurements of RF electric field. This probe can measure the RF electric field in air and in biological media at 3 T and 4.7 T MRI systems and allows the estimation of the local SAR
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Huynh, Ngoc Trinh. "APPLICATION DES NANOCAPSULES LIPIDIQUES CHARGEES EN FERROCIPHENOL DANS LE TRAITEMENT DU GLIOBLASTOME." Phd thesis, Université d'Angers, 2011. http://tel.archives-ouvertes.fr/tel-00668962.
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Ce travail a pour but d'optimiser la chimiothérapie du glioblastome à l'aide de nanocapsules lipidiques (LNC) chargées en ferrociphénol (FcdiOH), un composé organo-métallique anticancéreux innovant. Différentes voies d'administration ont été envisagées : la voie locale par stéréotaxie (convection-enhanced delivery ou CED) (60 μL de LNC, 0.36 mg de FcdiOH/rat), l'injection intra-carotidienne et l'injection intraveineuse (400 μL de LNC, 2.4 mg de FcdiOH/rat). Sur le modèle 9L orthotopique, l'efficacité antitumorale du principe actif s'est avérée être proportionnelle à la dose injectée. Le traitement local par CED d'une suspension iso-osmolaire de LNC-FcdiOH a augmenté significativement la survie des rats traités par rapport à celle du groupe témoin (médiane de 28.5 jours au lieu de 25 jours). Le recouvrement par de longues chaines de poly(éthylène glycol) (DSPE-mPEG2000) a permis aux LNC ainsi pégylées d'améliorer leur temps de circulation sanguine avec l'obtention d'une demi-vie 4 fois plus longue et d'une aire sous la courbe 1.65 fois plus étendue que celles des LNC classiques. Cela a entraîné l'éradication de la tumeur 9L sous-cutanée après une seule injection intraveineuse de DSPE-mPEG2000-LNC-FcdiOH, montrant l'efficacité du ciblage passif obtenu avec ces nanovecteurs. En parallèle, l'injection intra-carotidienne représente une voie d'administration prometteuse pour la délivrance de principes actifs dans le cerveau. En effet, le traitement intra-carotidien à l'aide des LNC pégylées a permis d'augmenter de 20% la survie des rats porteurs d'un gliosarcome 9L intracérébral (médiane de 30 jours). Enfin, l'incorporation de peptides NFL-TBS à la surface des LNC semble être une approche intéressante dans le cadre d'un ciblage actif, des études préliminaires ayant mis en évidence un rat survivant jusqu'à 44 jours.
Books on the topic "TOS actif"
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Acti-vie-tes 1: Bonne Collation, Bonne Nutrition! Student Text. Nelson Engineering, 1997.
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Galle, Griet, and Kris Grimonprez, eds. Europees burgerschap in de klas. Leuven University Press, 2022. http://dx.doi.org/10.11116/9789461664570.
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De impact van de EU op het dagelijkse leven is enorm, maar niet altijd zichtbaar. Jongeren vormen tot geïnformeerde en mondige EU-burgers vraagt actief leren om hen voor te bereiden op maatschappelijke verantwoordelijkheid en democratische inspraak. Dit boek biedt een praktische handleiding voor alle leerkrachten in het secundair onderwijs en docenten in het hoger onderwijs die hun leerlingen en studenten kritisch burgerschap willen bijbrengen binnen verschillende vakken en opleidingen. Concrete casussen op basis van rechtszaken behandeld door het Hof van Justitie van de Europese Unie stimuleren studenten tot kritisch nadenken. De casussen illustreren treffend de impact van de EU in het dagelijkse leven van haar burgers op tal van maatschappelijke domeinen: van de interne markt en het vrije verkeer van goederen en personen, over thema’s als democratie, gelijkheid, privacy, sociale rechten, tot consumentenbescherming, milieu en migratie. Via een ruim aanbod van lesactiviteiten en werkvormen verleent het boek op een laagdrempelige wijze inzicht in het DNA van de EU en EU-burgerschap. Europees burgerschap in de klas is daarom een must-read voor iedereen die zelf Europees burgerschap beter wil begrijpen of jongeren wil stimuleren tot kritische reflectie hierover. Deze handleiding is ontstaan vanuit het Erasmus+project Case4EU en is geschreven door een multidisciplinair team van auteurs (recht, filosofie, politieke en sociale wetenschappen).
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Cursi, Floriana. The Scope and Function of Civil Wrongs in Roman Society. Edited by Paul J. du Plessis, Clifford Ando, and Kaius Tuori. Oxford University Press, 2016. http://dx.doi.org/10.1093/oxfordhb/9780198728689.013.49.
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The earliest evidence of Roman delicts is to be found in the rules of the XII Tables which introduced the first types of delict and obligation. From these rules the Roman lawyers did not develop a general law of delict governing the delictual liability. The Roman system of delicts was in fact typical: with new delicts emerging until the first century BC. Simultaneously, during the final Republican period, the praetor introduced some actions for reparation of damage, later included by Justinian in quasi delict category. But the Roman system of delicts, was too typical to ensure the total reparation of the private damages deriving from an unlawful conduct. So actio de dolo was introduced to repair the loss caused by dolus, in case of absence of any specific delictual action. This was a subsidiary remedy, which filled the gaps of the typical system of actions.
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Bazen, Jacques, and Michiel Flooren. Ondernemerschap bij Saxion studenten, alumni en medewerkers : Een onderzoek naar de economische impact van Saxion spin-offs op de regio. Hogeschool Saxion, lectoraat Regio Ontwikkeling, 2020. http://dx.doi.org/10.14261/c61c0676-e78f-4de0-87b82ac2a66d86d9.
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Saxion hogeschool daagt studenten en medewerkers uit om na te denken over de impact van technologie op mens, maatschappij en milieu. Door praktijkgericht onderzoek vinden studenten en docent-onderzoekers samen slimme oplossingen voor vraagstukken die aanleiding kunnen geven tot ondernemerschap. Onderzoek naar de impact van Saxion op ondernemerschap bepaalt in belangrijke mate de onderzoeksagenda van academies in het economisch domein en in het bijzonder van de School of Commerce & Entrepreneurship. Dit document betreft een studie naar het ondernemerschap van studenten, alumni en (oud) medewerkers van Saxion en meer specifiek op de vraag hoe de economische impact van Saxion spin-offs zich heeft ontwikkeld in de regio Twente en de Cleantechregio gedurende de periode 2011-2019. Deze regionale focus wordt bepaald door de vestigingsplaatsen van Saxion in Enschede, Deventer en Apeldoorn. Saxion draagt in toenemende mate bij aan succesvolle spin-offs in de Cleantechregio en Twente. Bovendien creëert deze spin-off een groeiende werkgelegenheid. Deze bijdrage komt tot stand doordat Saxion haar betrokkenen deelnemers op diverse manieren traint en stimuleert om een bedrijf te starten en innovatieve diensten & producten te ontwikkelen. Hoeveel (toekomstige) bedrijven daadwerkelijk opgericht en/of overgenomen worden hangt af van de sector, het succes van de deelnemers en regionale karakteristieken. Indien de spin-off in beide regio’s onderling wordt vergeleken blijkt er door de onderlinge diversiteit sprake van een zgn. ‘couleur locale’. In de periode 2011-2019 zijn in totaal 1594 bedrijven opgericht of gekocht door een Saxion student, almumni of (oud) medewerker. Van deze bedrijven zijn er in 2019 nog 1041 commercieel actief waarvan er 982 nog steeds geleid worden door een Saxion betrokkene. In 2019 leveren deze bedrijven 15743 arbeidsplaatsen waarbij de gemiddelde bedrijfsgrootte 15 arbeidsplaatsen telt. Indien we kijken naar spin-offs die nog steeds door Saxion betrokkenen worden geleid, tellen deze bedrijven een kleiner aantal personeelsleden met gemiddeld 4.9 per bedrijf in Twente en slechts 2.8 in de Cleantech regio.
Book chapters on the topic "TOS actif"
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NODA, Y., and S. SASAKI. "Actin-binding channels." In Advances in Vasopressin and Oxytocin — From Genes to Behaviour to Disease, 551–57. Elsevier, 2008. http://dx.doi.org/10.1016/s0079-6123(08)00442-1.
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Goode, Bruce L. "Purification of yeast actin and actin-associated proteins." In Guide to Yeast Genetics and Molecular and Cell Biology Part C, 433–41. Elsevier, 2002. http://dx.doi.org/10.1016/s0076-6879(02)51862-0.
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Gittins, Heli, Sophie Wynne-Jones, and Val Morrison. "Woodlands and wellbeing: evaluating the 'Actif Woods Wales' programme." In A Modern Guide to Wellbeing Research, 207–27. Edward Elgar Publishing, 2021. http://dx.doi.org/10.4337/9781789900163.00022.
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Radler, Charlotte. "Actio et Contemplatio/Action and Contemplation." In The Cambridge Companion to Christian Mysticism, 211–22. Cambridge University Press, 2012. http://dx.doi.org/10.1017/cco9781139020886.015.
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Adams, Alison E. M., and John R. Pringle. "[51] Staining of actin with fluorochrome-conjugated phalloidin." In Guide to Yeast Genetics and Molecular Biology, 729–31. Elsevier, 1991. http://dx.doi.org/10.1016/0076-6879(91)94054-g.
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"Subcortical Aphasia: Evidence from Stereot Actic Surgical Lesions." In The Sciences of Aphasia: From Therapy to Theory, 65–92. BRILL, 2003. http://dx.doi.org/10.1163/9789004488038_008.
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Dimke-Kamola, Jolanta. "Sztuka, która przemienia sumienia. Uwagi o roli actio w XVI-wiecznym kaznodziejstwie." In Przejścia i przemiany w dawnych literaturach romańskich. Tom poświęcony pamięci Profesor Krystyny Kasprzyk. Warsaw University Press, 2016. http://dx.doi.org/10.31338/uw.9788323525295.pp.45-54.
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Weststeijn, Willem. "Aleida Schot-prijs." In Vertalerslexicon voor het Nederlandstalig gebied. University of Groningen, 2019. http://dx.doi.org/10.33612/lex.60d0828318d03.
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‘Aleida G. Schot, vermaard om haar vertalingen uit de Russische literatuur, overleed in 1969. Gedreven als zij was door haar liefde en haar eerbied voor de kunst van het vertalen, liet zij een fonds na ter uitreiking van een vertaalprijs.’ Zo begint het ‘Ter inleiding’ in de brochure die werd uitgegeven naar aanleiding van de eerste uitreiking van de Aleida Schot-prijs in 1981. In de brochure wordt ook kort aangegeven waarom de naar haar genoemde prijs pas twaalf jaar na Aleida Schots overlijden voor het eerst werd toegekend. Bij haar beschikking had Aleida Schot drie personen aangewezen die ervoor zorg moesten dragen dat de prijs werd ingesteld, maar deze ‘waren er niet toe gekomen aan deze opdracht te voldoen’. De werkelijke reden dat er geen actie werd ondernomen, was dat er in het fonds te weinig middelen waren om, geregeld, een prijs uit te keren. Die middelen kwamen er wel nadat vrienden van Aleida Schot in 1979 een comité hadden samengesteld om haar laatste wens ten uitvoer te brengen. Stuwende kracht achter het comité was mr. H.C.S. Warendorf, bij wie Aleida Schot geregeld aan huis kwam en die ‘tante Leidje’ daardoor goed had gekend. Leden van het comité en vervolgens bestuursleden van de opgerichte Aleida Schot Stichting waren, behalve mr. Warendorf, prof.mr. A. Pitlo, mr. J. Oranje, mevr. M. van Doveren-Nopol en dr. H. Bonger. Het waren allen vrienden van Aleida Schot; geen van hen had iets te maken met de slavistiek. Tot op heden is mr. Warendorf de belangrijkste mecenas van de Stichting; zonder hem zou de Aleida Schot-prijs niet hebben bestaan. Het bestuur van de Stichting bepaalde dat de prijs (5000 gulden, later 2500 euro) eens in de twee jaar zou worden toegekend en beperkt zou blijven tot vertalingen van literatuur uit de Slavische talen.
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"6. Regulation of actin dynamics by stress-activated protein kinase 2 (SAPK2)-dependent phosphorylation of heat-shock protein of 27 kDa (Hsp27)." In Cellular Responses to Stress, 79–90. Princeton University Press, 1999. http://dx.doi.org/10.1515/9781400865048.79.
Full textConference papers on the topic "TOS actif"
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Zu, Di, Xintao Zhao, Guangjie Cui, Zhijia Zhang, and Somin Eunice Lee. "Live cell probes for continuous visualization of actin dynamics." In Frontiers in Biological Detection: From Nanosensors to Systems XIV, edited by Benjamin L. Miller, Sharon M. Weiss, Amos Danielli, Ramesh Raghavachari, and Mikhail Y. Berezin. SPIE, 2022. http://dx.doi.org/10.1117/12.2610126.
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Kosoff, Rachelle E., and Jonathan Chernoff. "Abstract A40: Megakaryocyte endomitosis requires Pak2 to regulate actin and microtubule networks." In Abstracts: AACR Special Conference on Hematologic Malignancies: Translating Discoveries to Novel Therapies; September 20-23, 2014; Philadelphia, PA. American Association for Cancer Research, 2015. http://dx.doi.org/10.1158/1557-3265.hemmal14-a40.
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Prudnikov, Igor, Anton Smirnov, and Volodymyr Tsyvkin. "The actin cytoskeleton is a key element of the apoptosome assembly in the developing brain." In Cell-to-Cell Metabolic Cross-Talk in Physiology and Pathology. Basel, Switzerland: MDPI, 2020. http://dx.doi.org/10.3390/cells2020-08923.
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Hongsheng Li, Tian Shen, Matthew B. Smith, Ikuko Fujiwara, Dimitrios Vavylonis, and Xiaolei Huang. "Automated actin filament segmentation, tracking and tip elongation measurements based on open active contour models." In 2009 IEEE International Symposium on Biomedical Imaging: From Nano to Macro (ISBI). IEEE, 2009. http://dx.doi.org/10.1109/isbi.2009.5193303.
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Carapirea, Anatoli. "Cercetări privind influența preparatului biologic activ din levuri asupra parametrilor productivi și de reproducție la suine." In National Scientific Symposium With International Participation: Modern Biotechnologies – Solutions to the Challenges of the Contemporary World. Institute of Microbiology and Biotechnology, Republic of Moldova, 2021. http://dx.doi.org/10.52757/imb21.065.
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Berndt, M. "STRUCTURE AND FUNCTION OF THE GLYCOPROTEIN Ib-IX COMPLEX." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643729.
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At high shear flow, the adhesion of platelets to the exposed vascular subendothelium requires von Willebrand factor (vWF) and is dependent upon a specific platelet membrane adhesion receptor, the human platelet membrane glycoprotein (GP) Ib-IX complex. Recent evidence suggests that vWFbinding to the GP Ib-IX complex plays an important role in other key aspects of hemostasis and thrombosis such as shear-induced platelet aggregation and the interaction of platelets with fibrin.Studies in our laboratory with a seriesof murine monoclonal antibodies directed against epitopes on GP lb, GP IX, or against complex-specificepitopes indicate that GP lb and GP IX exist in the intact platelet membrane as a native heterodimer complex(-25,000 copies/platelet). By analysis onSDS-polyacrylamide gels, GP lb has an apparent molecular weight of 170,000 and cnsists of two disulfide-linked subunits, GP Iba (Mr = 135,000) and GP Ibβ (Mr = 25,000),whilst GP IX has an equivalent molecularweight under both nonreducing and reducing conditions (Mr = 22,000).The ±-chain ofGP lb has a central macroglycopeptide core (Mr =90,000) which is highly glycosylated. At each end of themacroglycopeptide region is a domainsensitive to proteolytic cleavage. Cleavage at the end proximal to the platelet membrane, e.g. by calpain, Serratia marcescens metalloprotease and trypsin, generates two fragments :a Mr =130,000 highly glycosylated fragment termed glycocalicin anda membrane-associated region consisting ofa Mr -25,000 fragment that remains disulfide-linkedto GP Ibβ and associated with GP IX. In resting platelets, the membrane-associated region spans the lipid bilayer linking the GP Ib-IX complex to the platelet endoskeleton via actin-binding protein. This membrane-associated region also contains the domain(s) recognized by quinine/quinidine drug-dependent antibodies. Cleavage at the plasma end of the macroglycopeptide, e.g. by human leukocyte elastase, generates a poorly glycosylated Mr = 45,000 fragment of GP Ibα (peptide tail region) and a heavily glycosylated Mr = 100,000 fragment that remains disulfide-linked to GP Ibg and associated with GP IX. Platelets lacking the N-terminal peptide tail region of GP Iba fail to agglutinate with ristocetin and vWF and show a delayed response to a-thrombin.Polyclonal and monoclonal antibodies against this region also inhibit both these platelet responses suggesting that the peptide tail region contains the binding sites for both α-thrombinand vWF. Rotary shadowingelectron microscopy of purified GP Ib-IX complex shows the structure to be highlyasymmetric with each complex existing asa flexible rod with a globular domain at each end. The overall length of the complexwas =60 nm.The smaller globular domain (peptidetail region) has a diameter of =9nm; the larger globular domain (membrane-associated region), a diameter of =16 nmWe have recently examined whetherthe human platelet GP Ib-IX complex is the receptor for the ristocetin-dependent binding of vWF by reconstitution with the purified components using a solid-phasebead assay. Our approach was to indirectlybind and orientate the GP Ib-IX complex onthe beads via a monoclonal antibody directed against the membrane-associated region of the complex (FMC 25, epitope on GP IX).Immunobeads were chosen as the insoluble matrix because they are uniform in size (=10μm in diameter), impermeable,specifically designed for the coupling of IgG, and because, like platelets, the beads have a net negative charge atneutral pH.Specific binding of 125I-labelled human vWF tothe GP Ib-IX complex-coated immunobeads was strictly ristocetin-dependent with maximal binding occurring atristocetin concentrations >1 mg/ml. Ristocetin-dependent specificbinding of 125I-labelled vWF was saturable.Scatchardanalysis revealed a single classof binding sites for vWF with purified GP Ib-IX complex.Monoclonal antibodies against the Mr = 45,000 peptide tail region ofGP lb which stronglyinhibitthe ristocetin-dependent binding ofvWF toplatelets also strongly inhibited the ristocetin-dependent binding of vWFto the GP Ib-IX coated beads. Monoclonalantibody against either themacroglycopeptide or membrane-associated regions of the GPIb-IX complex did not inhibit the ristocetin-dependent binding of vWF to platelets or to the GP Ib-IX complex-coated beads. Similar functional correlations were obtained with anti-vWFmonoclonal antibodies. The reconstitutiondata therefore confirm the functional roleof the GP Ib-IX complex as a major plateletvWF receptor. The region ofthe vWF molecule involved in binding to the GP Ib-IX complex has been localized toa Mr =50,000 domain towards theN-terminal end of the vWF subunit. The reconstitution assay should prove useful in the further definition of active peptides of vWF that bind tothe human platelet GP Ib-IX complex.
Reports on the topic "TOS actif"
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Reinhard, Stijn, Fred Kistenkas, Trond Selnes, Marie-Jose Smits, and Nathalie Steins. Van visie tot actie - een handelings-perspectief voor Nederland 2120 : Analyse van kansen en belemmeringen in voedselproductie voor een plan en routekaart voor Nederland 2120. Wageningen: Wageningen Economic Research, 2021. http://dx.doi.org/10.18174/550161.
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Sadot, Einat, Christopher Staiger, and Mohamad Abu-Abied. Studies of Novel Cytoskeletal Regulatory Proteins that are Involved in Abiotic Stress Signaling. United States Department of Agriculture, September 2011. http://dx.doi.org/10.32747/2011.7592652.bard.
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In the original proposal we planned to focus on two proteins related to the actin cytoskeleton: TCH2, a touch-induced calmodulin-like protein which was found by us to interact with the IQ domain of myosin VIII, ATM1; and ERD10, a dehydrin which was found to associate with actin filaments. As reported previously, no other dehydrins were found to interact with actin filaments. In addition so far we were unsuccessful in confirming the interaction of TCH2 with myosin VIII using other methods. In addition, no other myosin light chain candidates were found in a yeast two hybrid survey. Nevertheless we have made a significant progress in our studies of the role of myosins in plant cells. Plant myosins have been implicated in various cellular activities, such as cytoplasmic streaming (1, 2), plasmodesmata function (3-5), organelle movement (6-10), cytokinesis (4, 11, 12), endocytosis (4, 5, 13-15) and targeted RNA transport (16). Plant myosins belong to two main groups of unconventional myosins: myosin XI and myosin VIII, both closely related to myosin V (17-19). The Arabidopsis myosin family contains 17 members: 13 myosin XI and four myosin VIII (19, 20). The data obtained from our research of myosins was published in two papers acknowledging BARD funding. To address whether specific myosins are involved with the motility of specific organelles, we cloned the cDNAs from neck to tail of all 17 Arabidopsis myosins. These were fused to GFP and used as dominant negative mutants that interact with their cargo but are unable to walk along actin filaments. Therefore arrested organelle movement in the presence of such a construct shows that a particular myosin is involved with the movement of that particular organelle. While no mutually exclusive connections between specific myosins and organelles were found, based on overexpression of dominant negative tail constructs, a group of six myosins (XIC, XIE, XIK, XI-I, MYA1 and MYA2) were found to be more important for the motility of Golgi bodies and mitochondria in Nicotiana benthamiana and Nicotiana tabacum (8). Further deep and thorough analysis of myosin XIK revealed a potential regulation by head and tail interaction (Avisar et al., 2011). A similar regulatory mechanism has been reported for animal myosin V and VIIa (21, 22). In was shown that myosin V in the inhibited state is in a folded conformation such that the tail domain interacts with the head domain, inhibiting its ATPase and actinbinding activities. Cargo binding, high Ca2+, and/or phosphorylation may reduce the interaction between the head and tail domains, thus restoring its activity (23). Our collaborative work focuses on the characterization of the head tail interaction of myosin XIK. For this purpose the Israeli group built yeast expression vectors encoding the myosin XIK head. In addition, GST fusions of the wild-type tail as well as a tail mutated in the amino acids that mediate head to tail interaction. These were sent to the US group who is working on the isolation of recombinant proteins and performing the in vitro assays. While stress signals involve changes in Ca2+ levels in plants cells, the cytoplasmic streaming is sensitive to Ca2+. Therefore plant myosin activity is possibly regulated by stress. This finding is directly related to the goal of the original proposal.
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Sadot, Einat, Christopher Staiger, and Zvi Kam Weizmann. functional genomic screen for new plant cytoskeletal proteins and the determination of their role in actin mediated functions and guard cells regulation. United States Department of Agriculture, January 2003. http://dx.doi.org/10.32747/2003.7587725.bard.
Full textAbstract:
The original objectives of the approved proposal were: 1. To construct a YFP fused Arabidopsis cDNA library in a mammalian expression vector. 2. To infect the library into a host fibroblast cell line and to screen for new cytoskeletal associated proteins using an automated microscope. 3. Isolate the new genes. 4. Characterize their role in plants. The project was approved as a feasibility study to allow proof of concept that would entail building the YFP library and picking up a couple of positive clones using the fluorescent screen. We report here on the construction of the YFP library, the development of the automatic microscope, the establishment of the screen and the isolation of positive clones that are plant cDNAs encoding cytoskeleton associated proteins. The rational underling a screen of plant library in fibroblasts is based on the high conservation of the cytoskeleton building blocks, actin and tubulin, between the two kingdoms (80-90% homology at the level of amino acids sequence). In addition, several publications demonstrated the recognition of mammalian cytoskeleton by plant cytoskeletal binding proteins and vice versa. The major achievements described here are: 1. The development of an automated microscope equipped with fast laser auto-focusing for high magnification and a software controlling 6 dimensions; X, Y position, auto focus, time, color, and the distribution and density of the fields acquired. This system is essential for the high throughput screen. 2. The construction of an extremely competent YFP library efficiently cloned (tens of thousands of clones collected, no empty vectors detected) with all inserts oriented 5't03'. These parameters render it well representative of the whole transcriptome and efficient in "in-frame" fusion to YFP. 3. The strategy developed for the screen allowing the isolation of individual positive cDNA clones following three rounds of microscopic scans. The major conclusion accomplished from the work described here is that the concept of using mammalian host cells for fishing new plant cytoskeletal proteins is feasible and that screening system developed is complete for addressing one of the major bottlenecks of the plant cytoskeleton field: the need for high throughput identification of functionally active cytoskeletal proteins. The new identified plant cytoskeletal proteins isolated in the pilot screen and additional new proteins which will be isolated in a comprehensive screen will shed light on cytoskeletal mediated processes playing a major role in cellular activities such as cell division, morphogenesis, and functioning such as chloroplast positioning, pollen tube and root hair elongation and the movement of guard cells. Therefore, in the long run the screen described here has clear agricultural implications.
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Philosoph-Hadas, Sonia, Peter B. Kaufman, Shimon Meir, and Abraham H. Halevy. Inhibition of the Gravitropic Shoot Bending in Stored Cut Flowers Through Control of Their Graviperception: Involvement of the Cytoskeleton and Cytosolic Calcium. United States Department of Agriculture, December 2005. http://dx.doi.org/10.32747/2005.7586533.bard.
Full textAbstract:
Original objectives: The basic goal of the present project was to study the mechanism involved in shoot graviperception and early transduction, in order to determine the sequence of events operating in this process. This will enable to control the entire process of gravity-induced differential growth without affecting vertical growth processes essential for development. Thus, several new postulated interactions, operating at the perception and early transduction stages of the signaling cascade leading to auxin-mediated bending, were proposed to be examined in snapdragon spikes and oat shoot pulvini, according to the following research goals: 1) Establish the role of amyloplasts as gravireceptors in shoots; 2) Investigate gravity-induced changes in the integrity of shoot actin cytoskeleton (CK); 3) Study the cellular interactions among actin CK, statoliths and cell membranes (endoplasmic reticulum - ER, plasma membrane - PM) during shoot graviperception; 4) Examine mediation of graviperception by modulations of cytosolic calcium - [Ca2+]cyt, and other second messengers (protein phosphorylation, inositol 1,4,5-trisphosphate - IP3). Revisions: 1) Model system: in addition to snapdragon (Antirrhinum majus L.) spikes and oat (Avena sativa) shoot pulvini, the model system of maize (Zea mays) primary roots was targeted to confirm a more general mechanism for graviperception. 2) Research topic: brassinolide, which were not included in the original plan, were examined for their regulatory role in gravity perception and signal transduction in roots, in relation to auxin and ethylene. Background to the topic: The negative gravitropic response of shoots is a complex multi-step process that requires the participation of various cellular components acting in succession or in parallel. Most of the long-lasting studies regarding the link between graviperception and cellular components were focused mainly on roots, and there are relatively few reports on shoot graviperception. Our previous project has successfully characterized several key events occurring during shoot bending of cut flowers and oat pulvini, including amyloplast displacement, hormonal interactions and differential growth analysis. Based on this evidence, the present project has focused on studying the initial graviperception process in flowering stems and cereal shoots. Major conclusions and achievements: 1) The actin and not the microtubule (MT) CK is involved in the graviperception of snapdragon shoots. 2) Gravisensing, exhibited by amyloplast displacement, and early transduction events (auxin redistribution) in the gravitropic response of snapdragon spikes are mediated by the acto-myosin complex. 3) MTs are involved in stem directional growth, which occurs during gravitropism of cut snapdragon spikes, but they are not necessary for the gravity-induced differential growth. 4) The role of amyloplasts as gravisensors in the shoot endodermis was demonstrated for both plant systems. 5) A gravity-induced increase in IP.
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Philosoph-Hadas, Sonia, Peter Kaufman, Shimon Meir, and Abraham Halevy. Signal Transduction Pathway of Hormonal Action in Control and Regulation of the Gravitropic Response of Cut Flowering Stems during Storage and Transport. United States Department of Agriculture, October 1999. http://dx.doi.org/10.32747/1999.7695838.bard.
Full textAbstract:
Original objectives: The basic goal of the present project was to increase our understanding of the cellular mechanisms operating during the gravitropic response of cut flowers, for solving their bending problem without affecting flower quality. Thus, several elements operating at the 3 levels o the gravity-induced signal transduction pathway, were proposed to be examined in snapdragon stems according to the following research goals: 1) Signaling: characterize the signal transduction pathway leading to the gravitropic response, regarding the involvement of [Ca2+]cyt as a mediator of IAA movement and sensitivity to auxin. 2) Transduction by plant hormones: a) Examine the involvement of auxin in the gravitropic response of flower stems with regard to: possible participation of auxin binding protein (ABP), auxin redistribution, auxin mechanism of action (activation of H+-ATPase) mediation by changes in [Ca2+]cyt and possible regulation of auxin-induced Ca2+ action b: calmodulin-activated or Ca2+-activated protein kinases (PK). b) Examine the involvement of ethylene in the gravitropic response of flower stems with regard to auxin-induced ethylene production and sensitivity of the tissue to ethylene. 3) Response: examine the effect of gravistimulation on invertase (associated with growth and elongation) activity and invertase gene expression. 4) Commercial practice: develop practical and simple treatments to prevent bending of cut flowers grown for export. Revisions: 1) Model systems: in addition to snapdragon (Antirrhinum majus L.), 3 other model shoe systems, consisting of oat (Avena sativa) pulvini, Ornithogalun 'Nova' cut flowers and Arabidopsis thaliana inflorescence, were targeted to confirm a more general mechanism for shoot gravitropism. 2 Research topics: the involvement of ABP, auxin action, PK and invertase in the gravitropic response of snapdragon stems could not be demonstrated. Alternatively, the involvement in the gravity signaling cascade of several other physiological mediators apart of [Ca2+]cyt such as: IP3, protein phosphorylation and actin cytoskeleton, was shown. Additional topics introduced: starch statolith reorientation, differential expression of early auxin responsive genes, and differential shoot growth. Background to the topic: The gravitropic bending response of flowering shoots occurring upon their horizontal placement during shipment exhibits a major horticultural problem. In spite of extensive studies in various aboveground organs, the gravitropic response was hardly investigated in flowering shoots. Being a complex multistep process that requires the participation of various cellular components acting in succession or in parallel, analysis of the negative gravitropic response of shoot includes investigation of signal transduction elements and various regulatory physiological mediators. Major achievements: 1) A correlative role for starch statoliths as gravireceptors in flowering shoot was initially established. 2) Differentially phosphorylated proteins and IP3 levels across the oat shoe pulvini, as well as a differential appearance of 2 early auxin-responsive genes in snapdragon stems were all detected within 5-30 minutes following gravistimulation. 3) Unlike in roots, involvement of actin cytoskeleton in early events of the gravitropic response of snapdragon shoots was established. 4) An asymmetric IAA distribution, followed by an asymmetric ethylene production across snapdragon stems was found following gravistimulation. 5) The gravity-induced differential growth in shoots of snapdragon was derived from initial shrinkage of the upper stem side and a subsequent elongation o the lower stem side. 6) Shoot bending could be successfully inhibited by Ca2+ antagonists (that serve as a basis for practical treatments), kinase and phosphatase inhibitors and actin-cytoskeleton modulators. All these agents did not affect vertical growth. The essential characterization of these key events and their sequence led us to the conclusion that blocking gravity perception may be the most powerful means to inhibit bending without hampering shoot and flower growth after harvest. Implications, scientific and agriculture: The innovative results of this project have provided some new insight in the basic understanding of gravitropism in flower stalks, that partially filled the gap in our knowledge, and established useful means for its control. Additionally, our analysis has advanced the understanding of important and fundamental physiological processes involved, thereby leading to new ideas for agriculture. Gravitropism has an important impact on agriculture, particularly for controlling the bending of various important agricultural products with economic value. So far, no safe control of the undesired bending problem of flower stalks has been established. Our results show for the first time that shoot bending of cut flowers can be inhibited without adverse effects by controlling the gravity perception step with Ca2+ antagonists and cytoskeleton modulators. Such a practical benefit resulting from this project is of great economic value for the floriculture industry.
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Rousseau, Henri-Paul. De Gutenberg à ChatGPT: Le défi de l'université numérique. CIRANO, January 2023. http://dx.doi.org/10.54932/lrku8746.
Full textAbstract:
Le but de ce texte est de mieux cerner l’ampleur du défi que pose le monde numérique au milieu universitaire et de proposer quelques idées pouvant alimenter la réflexion des universitaires dans cette démarche d’adaptation au monde numérique. L’impact de la révolution numérique sur le monde de l’éducation universitaire peut se résumer à ceci : dans un monde numérique, les connaissances sont accessibles à tous et, somme toute à très faibles coûts alors que le niveau et les types de compétences requises pour évoluer dans un monde numérique sont plus complexes. L’université a perdu son quasi-monopole dans la transmission des connaissances et elle n’a pas encore établi pleinement son rôle, pourtant indispensable, dans l’acquisition des nouvelles compétences. L’université est également menacée dans sa capacité historique d’attirer, de retenir et de promouvoir les artisans du monde de demain qui sont de plus en plus actifs dans les écosystèmes animés et même souvent contrôlés par les grands gagnants industriels de la révolution numérique. Une réflexion et une discussion s’imposent. Le monde numérique étant un monde de données, d’information et de savoir, ce monde ne peut être que le monde naturel de la communauté des professeurs, des maîtres, des chercheurs et des étudiants. La numérisation de l’éducation est une chance unique pour le rendre plus accessible au plus grand nombre.
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Elroy-Stein, Orna, and Dmitry Belostotsky. Mechanism of Internal Initiation of Translation in Plants. United States Department of Agriculture, December 2010. http://dx.doi.org/10.32747/2010.7696518.bard.
Full textAbstract:
Original objectives Elucidation of PABP's role in crTMV148 IRES function in-vitro using wheat germ extract and krebs-2 cells extract. Fully achieved. Elucidation of PABP's role in crTMV148 IRES function in-vivo in Arabidopsis. Characterization of the physical interactions of PABP and other potential ITAFs with crTMV148 IRES. Partly achieved. To conduct search for additional ITAFs using different approaches and evaluate the candidates. Partly achieved. Background of the topic The power of internal translation via the activity of internal ribosomal entry site (IRES) elements allow coordinated synthesis of multiple gene products from a single transcription unit, and thereby enables to bypass the need for sequential transformation with multiple independent transgenes. The key goal of this project was to identify and analyze the IRES-trans-acting factors (ITAFs) that mediate the activity of a crucifer-infecting tobamovirus (crTMV148) IRES. The remarkable conservation of the IRES activity across the phylogenetic spectrum (yeast, plants and animals) strongly suggests that key ITAFs that mediate its activity are themselves highly conserved. Thus, crTMV148 IRES offers opportunity for elucidation of the fundamental mechanisms underlying internal translation in higher plants in order to enable its rational manipulation for the purpose of agricultural biotechnology. Major conclusions and achievements. - CrTMV IRES requires PABP for maximal activity. This conclusion was achieved by PABP depletion and reconstitution of wheat germ- and Krebs2-derived in-vitro translation assays using Arabidopsis-derived PABP2, 3, 5, 8 and yeast Pab1p. - Mutations in the internal polypurine tract of the IRES decrease the high-affinity binding of all phylogenetically divergent PABPs derived from Arabidopsis and yeast in electro mobility gel shift assays. - Mutations in the internal polypurine tract decrease IRES activity in-vivo. - The 3'-poly(A) tail enhances crTMV148 IRES activity more efficiently in the absence of 5'-methylated cap. - In-vivo assembled RNPs containing proteins specifically associated with the IRES were purified from HEK293 cells using the RNA Affinity in Tandem (RAT) approach followed by their identification by mass spectroscopy. - This study yielded a list of potential protein candidates that may serve as ITAFs of crTMV148 IRES activity, among them are a/b tubulin, a/g actin, GAPDH, enolase 1, ribonuclease/angiogenin inhibitor 1, 26S proteasome subunit p45, rpSA, eEF1Bδ, and proteasome b5 subunit. Implications, both scientific and agriculture. The fact that the 3'-poly(A) tail enhances crTMV148 IRES activity more efficiently in the absence of 5'-methylated cap suggests a potential joint interaction between PABP, the IRES sequence and the 3'-poly(A). This has an important scientific implication related to IRES function in general.
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Delmer, Deborah P., Douglas Johnson, and Alex Levine. The Role of Small Signal Transducing Gtpases in the Regulation of Cell Wall Deposition Patterns in Plants. United States Department of Agriculture, August 1995. http://dx.doi.org/10.32747/1995.7570571.bard.
Full textAbstract:
The combined research of the groups of Delmer, Levine and Johnson has led to a number of interesting findings with respect to the function of the small GTPase Rac in plants and also opened up new leads for future research. The results have shown: 1) The Rac13 protein undergoes geranylgeranlyation and is also translocated to the plasma membrane as found for Rac in mammals; 2) When cotton Rac13 is highly- expressed in yeast, it leads to an aberrant phenotype reminiscent of mutants impaired in actin function, supporting a role for Rac13 in cytoskeletal organization; 3) From our searches, there is no strong evidence that plants contain homologs of the related CDC42 genes found in yeast and mammals; 4) We have identified a rather unique Rac gene in Arabidopsis that has unusual extensions at both the N- and C-terminal portions of the protein; 5) New evidence was obtained that an oxidative burst characterized by substantial and sustained production of H202 occurs coincident with the onset of secondary wall synthesis in cotton fibers. Further work indicates that the H202 produced may be a signal for the onset of this phase of development and also strongly suggests that Rac plays an important role in signaling for event. Since the secondary walls of plants that contain high levels of lignin and cellulose are the major source of biomass on earth, understanding what signals control this process may well in the future have important implications for manipulating the timing and extent of secondary wall deposition. 6) When the cotton Rac13 promoter is fused to the reporter gene GUS, expression patterns in Arabidopsis indicate very strong and specific expression in developing trichomes and in developing xyelm. Since both of these cell types are engaged in secondary wall synthesis, this further supports a role for Rac in signaling for onset of this process. Since cotton fibers are anatomically defined as trichomes, these data may also be quite useful for future studies in which the trichomes of Arabidopsis may serve as a model for cotton fiber development; the Rac promoter can therefore be useful to drive expression of other genes proposed to affect fiber development and study the effects on the process; 7) The Rac promoter has also been shown to be the best so far tested for use in development of a system for transient transformation of developing cotton fibers, a technique that should have many applications in the field of cotton biotechnology; 8) One candidate protein that may interact with Rac13 to be characterized further in the future is a protein kinase that may be analogous to the PAK kinase that is known to interact with Rac in mammals.
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Knowles, Donald, and Monica Leszkowicz Mazuz. Transfected Babesia bovis expressing the anti-tick Bm86 antigen as a vaccine to limit tick infestation and protect against virulent challenge. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7598160.bard.
Full textAbstract:
Bovine babesiosis, caused by the apicomplexan parasites Babesiabovisand B. bigemina, is a major tick borne disease of cattle with significant economic importance globally. The vectors of Babesia parasites are R. (Boophilus) annulatusand R. microplus. In Israel these parasites are transmitted manly by R. annulatus. The main goal of the proposal was developing and testing a novel B. bovisvaccine based on stably transfected attenuated B. bovisexpressing the anti-tick Bm86 antigen. This required generating a transfected- attenuated B. bovisparasite containing a bidirectional promoter expressing both, the gfp- bsd selectable marker and the tick vaccine antigen Bm86. The vaccine was tested for its ability to elicit protective immune responses against T. annulatusticks. Efficient control of babesiosis is based on a complex scheme of integrated management, including preventive immunization, anti-babesial chemotherapy and control of tick populations. Live vaccines based on attenuated parasites are the most effective measure to control babesiosis, and are currently used in several countries, including Israel. Live attenuated parasites lead to a chronic infection and development of strong and long term immunity in vaccinated cattle. Still, live vaccines have several limitations, including the difficulty to distinguish among vaccinated and naturally infected cattle and potential for sporadic outbreaks in vaccinated animals. Tick limitation is essential to control babesiosis but the main measure to reduce tick infestation is traditionally approached using acaricides, which is limited by environmental concerns and the development of resistance by the ticks. Alternative tick-control measures including the use of anti-tick vaccines are emerging, and at least partial protective immunity has been achieved against tick vectors by vaccination with recombinant protective tick antigens (ie: Bm86). In addition, the Babesia vaccine development toolbox has been recently expanded with the development of transfection technology in Babesia parasites. In this approved proposal we successfully developed a Babesia live attenuated transfected vaccine, which is able to express a B. bovisMSA-1 signal-Bm86 chimera and eGFP genes under the control of the B. bovisef- 1 and actin promoters respectively. Genetic analysis demonstrated specific stable integration of the transfected genes in the expected ef-1 locus, and immunofluorescence analysis confirmed expression of Bm86 in the surface of transfected parasites. When applied to splenectomized calves, the transfected parasites were able to cause persistent B. bovisinfection with production of antibodies reactive with Bm86 for at least six months. In addition, partial protection against ticks was also observed upon challenging the vaccinated animals with R. annulatuslarvae. However, when used on intact calves, the vaccine failed to elicit detectable immune responses against Bm86, and we are still in the process of interpreting the data and make necessary changes in our experimental approaches. Overall, the results obtained here represent a step forward towards the development of integrated vaccines against both ticks and tick –borne pathogens, using the Babesia attenuated parasites as a platform to the delivery of exogenous protective antigens
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Yaron, Zvi, Martin P. Schreibman, Abigail Elizur, and Yonathan Zohar. Advancing Puberty in the Black Carp (Mylopharyngodon Piceus) and the Striped Bass (Morone Saxatilis). United States Department of Agriculture, August 1993. http://dx.doi.org/10.32747/1993.7568102.bard.
Full textAbstract:
The black carp (bc)GtH IIb cDNA was amplified and isolated, cloned and sequenced. Comparison of the bcGtH IIb deduced a.a. sequence with that of GtH IIb from other teleosts revealed high homology to cyprinid species and a lower homology to salmonid or perciform fish. The gene coding for the GtH IIb was isolated and sequenced. Three bc recombinant phages which hybridized to the goldfish GtH Ib cDNA probe were isolated and are currently being characterized. The region coding for the mature GtH IIb was expressed in a bacterial expression vector resulting in the production of a recombinant protein. In vitro folding resulted in a protein only 1.3% of which displaced the native common carp GtH II in a RIA. Therefore, the common carp GtH RIA was utilized for the physiological studies at the current phase of the project. Two non-functional sites were identified along the brain-pituitary gonadal axis in the immature black carp. The pituitary is refractory to GnRH stimulation due to a block proximal to the activation of PKA and PKC probably at the level of GnRH receptors. The gonads, although capable of producing steroids, are refractory to gonadotropic stimulation but do respond to cAMP antagonists, indicating a block at the GtH receptor level. Attempts to advance puberty in 2 and 3 y old black carp showed that testosterone (T) stimulates GtH synthesis in the pituitary and increases its sensitivity to GnRh. A 2 month treatment combining T+GnRH increased the circulating GFtH level in 3 y old fish. Addition of domperidone to such a treatment facilitated both the accumulation of GtH in the pituitary and its response to GnRH. The cDNA of striped bass GtH a, Ib and IIb subunits were amplified, isolated, cloned and sequenced, and their deduced a.a. sequences were compared with those of other teleosts. A ribonuclease protection assay was developed for a sensitive and simultaneous determination of all GtH subunits, and of b-actin mRNAs of the striped bass. GnRH stimulated dramatically the expression of the a and GtH IIb subunits but the level of GtH Ib mRNA increased only moderately. These findings suggest that GtH-II, considered in salmonids to be involved only in final stages of gametogenesis, can be induced by GnRH to a higher extent than GtH-I in juvenile striped bass. The native GtH II of the striped bass was isolated and purified, and an ELISA for its determination was developed. The production of all recombinant striped bass GtH subunits is in progress using the insect cell (Sf9) culture and the BAC-TO-BAC baculovirus expression system. A recombinant GtH IIb subunit has been produced already, and its similarity to the native subunit was confirmed. The yield of the recombinant glycoprotein can reach 3.5 mg/ml after 3 days culture. All male striped bass reach puberty after 3 y. However, precocious puberty was discovered in 1 and 2 y old males. Females become vitellogenic during their 4th year. In immature 2 y old females, T treatment elevates the pituitary GtH II content while GnRH only potentiates the effect. However, in males GnRH and not T affects GtH accumulation in the pituitary. Neither GnRH, nor T treatment resulted in gonadal growth in 2 y old striped bass, indicating that either the accumulated GtH II was not released, or if released, the gonads were refractory to GtH stimulation, similar to the situation in the immature black carp. In 3 y old female striped bass, 150 day GnRHa treatment resulted in an increase in GSI, while T treatment, with or without GnRHa, resulted in a decrease in oocyte diameter, similar to the effect seen in the black carp. Further attempts to advance puberty in both fish species should take into account the positive effect of T on pituitary GtH and its negative effect of ovarian growth.