Tesis sobre el tema "Motility"
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Cao, Luyan. "bases structurales de la motilité des kinésines". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS267/document.
Texto completoKinesins are a family of microtubule-interacting motor proteins that convert the chemical energy from ATP hydrolysis into mechanical work. Many kinesins are motile, walking along microtubules to fulfill different functions. Most kinesins are dimers, the monomer comprising a motor domain, a dimerizing stalk domain, and a tail domain. The motor domain contains both the nucleotide-binding site and the microtubule-binding site. I am interested in the molecular mechanism of kinesin's motility. In particular I want to establish the structural variations of the kinesin motor domain along with the mechanochemical cycle of this motor protein. During my thesis, I have focused my work on the human kinesin-1, also named conventional kinesin, which is the best characterized kinesin.I have studied two aspects of the kinesin mechanochemical cycle, by combining structural and mutational approaches. Both aspects rely on the binding of ADP-kinesin to a microtubule, which leads to the release of the nucleotide and to a tight kinesin-microtubule association. First I determined the crystal structure of nucleotide-free kinesin-1 motor domain in complex with a tubulin heterodimer, which is the building block of microtubule. This structure represented the main missing piece of the structural cycle of kinesin. Three subdomains in the kinesin motor domain can be identified through the comparison of my structure with ATP-analog kinesin-1-tubulin structure. The relative movements of these subdomains explain how ATP binding to apo-kinesin bound to microtubule triggers the opening of a hydrophobic cavity, 28 Å distant from the nucleotide-binding site. This cavity accommodates the first residue of the “neck linker”, a short peptide that is C-terminal to the motor domain, allowing the neck linker to dock on the motor domain. The docking of the neck linker is proposed to trigger the mechanical step, i.e. the displacement of the cargo and the stepping of the dimeric kinesin. By studying mutants of the neck linker, I have shown that, reciprocally, this peptide locks kinesin in the ATP state, which is also the conformation efficient for ATP hydrolysis. Doing so, it prevents the motor domain from switching back to the apo-state. It prevents also an untimely hydrolysis of ATP, before the mechanical step has occurred. These features are required for movement and processivity.Second, these structural data also suggest how the binding of ADP-kinesin to tubulin enhances nucleotide release from kinesin. To further study this step of the kinesin cycle, I studied the effect of kinesin-1 mutations. These mutations were designed in isolated kinesin to mimic the state when kinesin is bound to a microtubule. I identified two groups of mutations leading to a high spontaneous ADP dissociation rate, suggesting that there are two ways to interfere with ADP binding. Then I determined the crystal structures of the apo form of two mutants as well as that of the nucleotide-depleted wild type kinesin. It showed that apo-kinesin adopts either and ADP-like conformation or a tubulin-bound apo-like one. In the natural context, the second one is stabilized upon microtubule binding. Overall, the mutational and structural data suggest that microtubules accelerate ADP dissociation in kinesin by two main paths, by interfering with magnesium binding and by destabilizing the nucleotide-binding P-loop motif
Gholami, Azam. "Actin-based motility". Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-72151.
Texto completoPatankar, RoySuneel V. "Studies in gallbladder motility". Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296188.
Texto completoUllah, Sana. "Factors governing gastrointestinal motility". Thesis, University of Hull, 2012. http://hydra.hull.ac.uk/resources/hull:7166.
Texto completoStanley, Hugh Gerard. "Neural mechanisms in abomasal motility". Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/30009.
Texto completoRoss, Oliver N. "Algal motility in variable turbulence". Thesis, University of Southampton, 2004. https://eprints.soton.ac.uk/45995/.
Texto completoBiondini, Marco. "RALlying through cell motility and invasion". Thesis, Paris 11, 2014. http://www.theses.fr/2014PA11T042.
Texto completoMetastasis is a multistep process by which cancer cells migrate away from the primary neoplastic mass to give rise to secondary tumors at distant sites. Thus, the acquisition of motility and invasive traits by tumor cells is a crucial step for metastasis to occur. Depending on the cell type and the environment, cells can move collectively keeping stable cell-cell contacts or as individual cells, which translocate by exploiting either mesenchymal or amoeboid motility programs.Different molecules and pathways have been linked to the regulation of cell motility. Rho small GTPases (Rac1, Cdc42 and RhoA) control cell migration through their actions on actin assembly, actomyosin contractility and microtubules. Rac1 drives mesenchymal-type motility by promoting lamellipodia formation via the Wave Regulator Complex (WRC). On the contrary, amoeboid motility is governed by RhoA which promotes cell movement via the generation of actomyosin contractile force. Another family of small GTPases, the Ral proteins, was recently involved in the regulation of cell migration. RalB, through the mobilization of its main effector the Exocyst complex, was shown to play an essential role in cell motility. In this work of thesis we investigated the molecular mechanisms through which RalB/Exocyst pathway controls cell motility and invasion.In the first part of this manuscript we show that Exocyst interacts with the RacGAP SH3BP1 (project 1). In mesenchymal moving cells Exocyst/SH3BP1 interaction is required to organize membrane protrusion formation by spatially regulating the activity of Rac1 at the cellular front. In addition, in project 2, we show that the Exocyst binds to the wave regulator complex (WRC), a key promoter of actin polymerization. We provide evidences for Exocyst to be involved in driving the WRC to the leading edge of motile cells, where it can stimulate actin polymerization and membrane protrusions. Reactivation of a developmental program termed epithelial-mesenchymal transition (EMT) was recently shown to promote motility, invasion and metastasis of neoplastic cells. Tumor cells undergoing EMT loose cell-cell contacts acquire a fibroblastoid phenotype and invade the surrounding tissues as individual cells. In project 3 we characterized the invasion plasticity of cancer cells after EMT and we investigated the molecular contribution of Ral to post-EMT invasion. We showed that upon EMT cells disseminate individually in a Rho-driven fashion exploiting the generation of actomyosin force to deform the extracellular matrix. We document that RalB silencing severely impairs actomyosin contractility and dissemination of post-EMT cells. We hypothesize that RalB regulates invasion by controlling the dynamics of the Rho pathway via the Exocyst-associated RhoGEF GEF-H1 in post-EMT cells. Finally, in the last part of this thesis manuscript, we present the PIV-based “AVeMap” software which has been developed to quantify in a fully automated way cell migration and its parameters (Project 4).Taken together the results presented in this thesis manuscript point out the Ral/Exocyst pathway as a key molecular organizer of the execution of both Rac1- and Rho-driven motility programs
Chemeris, Angelina. "Régulation du suppresseur d'invasion Arpin par les Tankyrases". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX073.
Texto completoThe evolutionarily conserved Arp2/3 complex plays a central role in nucleating the branched actin filament arrays that drive cell migration, endocytosis, and other processes. Recently, an inactivator of the Arp2/3 complex at the lamellipodium tip, a small protein, Arpin, was discovered and characterized. On its C-terminus, Arpin possesses an acidic (A) motif, which is homologous to the A-motif of various Nucleation Promoting Factors (NPFs). It was predicted that Arpin can bind at two binding sites to the Arp2/3 complex, similar to VCA domains of NPFs. Here, we used single particle electron microscopy to obtain a 3D reconstruction of the Arp2/3 complex bound to Arpin at a 25Å resolution. We showed that the binding of Arpin causes the standard open conformational of the Arp2/3 complex. We confirmed that there are two binding sites on the Arp2/3 complex for Arpin: one on the back of the Arp3 subunit, and the second is located between Arp2 and ARPC1 subunits. The distance between the Arp2/3 complex and Arpin (5 nm) supports the view that Arpin interacts with its partner via its unstructured C-terminal acidic tail.Next, using the pull-down assay, we identified the new Arpin binding partners, Tankyrases1/2. Interestingly, Tankyrases and the Arp2/3 complex possess overlapping amino acid sequences at Arpin binding sites. Hence, we demonstrated a competition between the ARC4 domain of Tankyrase1 and the Arp2/3 complex in a dose-dependent manner.To understand the principles of Tankyrases-Arpin interaction, we created a mutant Arpin (ArpinG218D) that lacks its ability to interact with Tankyrases, but not with the Arp2/3 complex in vitro. Interestingly, ArpinG218D was not able to inhibit the Arp2/3 complex in vivo, suggesting that Tankyrase may be necessary for Arpin-Arp2/3 complex interaction. Arpin is the turning factor of migrating cells, so we performed a migration analysis of MCF10-A cells expressing either wild type Arpin (ArpinWT) or mutant ArpinG218D in parallel with the depletion of endogenous Arpin. Cells expressing ArpinG218D had higher directional persistence, similar to the cells where the endogenous Arpin was knocked down. Thus, we suggested that mutant ArpinG218D cannot inactivate the Arp2/3 complex since it is not present at the lamellipodial tip. We compared the amount of protein for both ArpinWT and ArpinG218D in the membrane fraction of the migrating cells. A significant difference (44%) in the amount of ArpinWT and Arpin G218D was consistent with our hypothesis.Tankyrases are therapeutic targets in a variety of cancers, but currently there is no structural model available for these large and flexible proteins. In this work, we obtained for the first time two 3D reconstructions of full-length Tankyrase1 and Tankyrase1 bound to Arpin using single particle electron microscopy. The achieved resolution (27Å) was enough to detect a dramatic conformational change in Tankyrase SAM and PARP domains upon binding of Arpin molecules. In our reconstruction, three Arpins were bound to the ARC1, ARC4 and ARC5 domains of Tankyrase1. ARC5 was shown to be the most flexible part of the ARC cluster.Based on the obtained data, we suggested a model of regulation of the activity of Arpin by Tankyrases. According to our model, Tankyrases bind Arpin in the cytoplasm, change their conformational state and bring Arpin closer to the membrane in the lamellipodia. Deciphering the extracellular signals, Rac GTPase activates Arpin, which sequentially inactivates the Arp2/3 complex, while Tankyrases are released
Macdonald, Julie. "Studies on motility in Rhodomicrobium vannielii". Thesis, University of Warwick, 1987. http://wrap.warwick.ac.uk/98453/.
Texto completoWang, Qingqi. "Regulation of motility in Listeria monocytogenes". Thesis, University of Nottingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490996.
Texto completoReid, Keith. "Gastrointestinal motility in vection induced nausea". Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299548.
Texto completoLister, Ida Margaret Bonnevie. "Myosin VI : relating motility to function". Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620603.
Texto completoTozluoglu, M. "Multiscale modelling of cancer cell motility". Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1383588/.
Texto completoGadelha, Hermes. "Mathematical modelling of human sperm motility". Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:34a11669-5d14-470b-b10b-361cf3688a30.
Texto completoFerreira, Rita Joana Rodrigues da Silva Rua. "Cilia motility studies in zebrafish embryos". Master's thesis, Faculdade de Ciências e Tecnologia, 2012. http://hdl.handle.net/10362/7984.
Texto completoMotile ciliary dysfunctions cause specific Ciliopathies that affect mainly the respiratory tract, fertilization and left-right body establishment. The embryonic organ where left-right decisions are first taken is called the organizer, a ciliated organ where a leftward cilia driven fluid-flow is generated. The organizer is named node in the mouse and Kupffer’s vesicle (KV) in zebrafish. The correct left-right axis formation is highly dependent on signaling pathways downstream of such directional fluid-flow. Motile cilia need to be coordinated and Ciliary Beat Frequency (CBF) is characteristic of different types of cilia depending on their function. Using zebrafish as a model, our group has been studying cilia length regulation and motility in wild-type and deltaD-/- mutant embryos. Recently, we showed that Notch signalling was directly involved in the control of cilia length in the KV cells given that the deltaD-/- mutant present shorter KV cilia. The goal of this project was to characterize the CBF of deltaD-/- KV cilia vs. wild-type cilia and reveal how potential differences in CBF impact on KV fluid flow, using spectral analysis associated with highspeed videomicroscopy. By decomposing and comparing the obtained CBF with Fast Fourier Transform, we identified two major populations of motile cilia in wild-type as well as in deltaD-/- mutant embryos. However, we found the CBF populations had differential relative contributions and different distributions between wild-type and mutant embryos. Furthermore, by measuring the velocity of native particles we studied the KV fluid-flow and concluded that the dispersion of the flow velocity was much wider in the deltaD-/- mutants. On the other hand, based on a gene expression study of motility genes downstream of DeltaD, we concluded that motility related genes (dnah7, rsph3 and foxj1a) were deregulated in the mutants. During this project we generated data that led to new hypotheses that will allow us to test the causality between the described correlations.
Rucka, Marta. "Metabolic regulation of tumour cell motility". Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/380962/.
Texto completoRyan, A. J. "Polymer Nanotechnology: the Quest for Motility". Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35017.
Texto completoLuman, Widjaja. "Biliary motility in health and disease". Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/20639.
Texto completoEng, Mabel. "Ocular motility and associated eye disorders /". Online version of thesis, 1992. http://hdl.handle.net/1850/10885.
Texto completoO'Toole, Christine M. B. "The development of motility in spermatozoa". Thesis, London Metropolitan University, 1994. http://repository.londonmet.ac.uk/3229/.
Texto completoSpear, Estelle Trego. "Altered Gastrointestinal Motility in Multiple Sclerosis". ScholarWorks @ UVM, 2018. https://scholarworks.uvm.edu/graddis/837.
Texto completoO'Callaghan, Michael Edward. "The role of NMDA receptors in colonic mechanosensation and motility NMDA receptors significantly modulate spontaneous distal colonic motility but not mechanosensation or electrically stimulated motility in the rat /". Title page and abstract only, 2004. http://web4.library.adelaide.edu.au/theses/09SB/09sbo152.pdf.
Texto completoRiccioni, Kara. "INFLUENCE OF ERGOT ALKALOIDS ON RUMEN MOTILITY: TIME AND CONCENTRATION OF ERGOVALINE + ERGOVALININE REQUIRED TO IMPACT RETICULORUMEN MOTILITY". UKnowledge, 2017. http://uknowledge.uky.edu/animalsci_etds/77.
Texto completoSuranemi, Praveen K. "Arp2/3 complex in mammalian cell motility". Thesis, Open University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548065.
Texto completoLoitto, Vesa-Matti. "Towards a Refined Model of Neutrophil Motility". Doctoral thesis, Linköping : Univ, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5142.
Texto completoActon, S. E. "Mechanisms of cancer cell motility in vivo". Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1387309/.
Texto completoPinner, Sophie Elizabeth. "Mechanisms of cancer cell motility in vivo". Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1444471/.
Texto completoBai, Limiao y 白利苗. "In silico simulation of actin-based motility". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B46429116.
Texto completoFoynes, Susan. "Motility and chemotaxis studies in Helicobacter pylori". Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322447.
Texto completoMcLachlan, Deirdre. "Benthic diatom motility in response to light". Thesis, University of Essex, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435583.
Texto completoGodeau, Amélie. "Cyclic contractions contribute to 3D cell motility". Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAF038/document.
Texto completoCell motility is an important process in Biology. It is mainly studied on 2D planar surfaces, whereas cells experience a confining 3D environment in vivo. We prepared a 3D Cell Derived Matrix (CDM) labeled with fluorescently labeled fibronectin, and strikingly cells managed to deform the matrix with specific patterns : contractions occur cyclically with two contraction centers at the front and at the back of the cell, with a period of ~14 min and a phase shift of ~3.5 min. These cycles enable cells to optimally migrate through the CDM, as perturbation of cycles led to reduced motility. Acto-myosin was established to be the driving actor of these cycles, by using specific inhibitors. We were able to trigger cell motility externally with local laser ablations, which supports this framework of two alternating contractions involved in motion. Altogether, this study reveals a new mechanism of dynamic cellular behaviour linked to cell motility
Lee, Allen S. M. Massachusetts Institute of Technology. "Symmetry-breaking motility and RNA secondary structures". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/34396.
Texto completoIncludes bibliographical references (p. 61-64).
This thesis contains work on three separate topics: the spontaneous motility of functionalized particles, the designability of RNA secondary structures, and the statistical mechanics of homopolymer RNAs. For the work on spontaneous motility, we were motivated by in vitro experiments investigating the symmetry-breaking motility of functionalized spherical beads to develop a general theory for the dynamics of a rigid object propelled by an active process at its surface. Starting from a phenomenological expansion for the microscopic dynamics, we derive equations governing the macroscopic velocities of the object near an instability towards spontaneous motion. These equations respect symmetries in the object's shape, with implications for the phase behavior and singularities encountered at a continuous transition between stationary and moving states. Analysis of the velocity fluctuations of such an object reveals that these fluctuations differ qualitatively from those of a passive object. For the work on designability, we investigated RNA folding within a toy model in which RNA bases come in two types and complementary base pairing is favored. Following a geometric formulation of biopolymer folding proposed in the literature, we represent RNA sequences and structures by points in a high-dimensional "contact space." Designability is probed by investigating the distribution of sequence and structure points within this space. We find that one-dimensional projections of the sequence point distribution approach normality with increasing RNA length N.
(cont.) Numerical comparison of the structure point distribution with a Gaussian approximation generated by principal component analysis reveals discrepancies. The third and final project concerns the statistical mechanics of homopolymer RNAs. We compute the asymptotics of the partition function Zn and characterize the crossover length scale governing its approach to its leading asymptotic behavior. Consideration of restricted partition functions in which one or more base pairs are enforced leads to an interesting connection with ideal Gaussian polymers. We introduce the notion of gapped secondary structures and analyze the partition function Z?,) for RNAs of length n with gap at p. Another length scale emerges whose scaling agrees with that of the crossover scale found earlier.
by Allen Lee.
S.M.
Schreiber, Christian. "Excluded volume effects in actin based motility". Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608724.
Texto completoCastillo, Fortunato Dalrymple. "Computerised analysis of patterns of intestinal motility". Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/843705/.
Texto completoLavi, Ido. "Physical modeling of cell motility and morphodynamics". Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS237.
Texto completoThis thesis introduces a minimal hydrodynamic model of polarization, migration, and deformation of a biological cell confined between two parallel surfaces. Our model describes the cell cytoplasm as a viscous droplet that is driven by an active cytoskeleton force, itself controlled by a diffusive cytoplasmic solute. A linear stability analysis of this two-dimensional system reveals that solute activity first destabilizes a global polarization-translation mode, prompting cell motility through spontaneous-symmetry-breaking. At higher activity, the system crosses a series of Hopf bifurcations leading to coupled oscillations of droplet shape and solute concentration profiles. At the nonlinear level, we find traveling-wave solutions associated with unique polarized shapes that resemble experimental observations. In addition, we developed a numerical simulation of our moving-boundary problem based on the finite element method. The numerical study demonstrated the stability of our traveling-wave solutions, the existence of sustained oscillatory attractors, and the emergence of a finite-time pinch-off singularity. By incorporating mechanical interactions with the external environment, we explored cell scattering from stationary walls and obstacles, migration through imposed micro-geometries, and cell-cell collisions. These exercises capture a range of nontrivial patterns resulting from the intrinsic memory and deformability of the cell. Altogether, our work offers a mathematical paradigm of active deformable systems in which Stokes hydrodynamics are coupled to diffusive force-transducers
Relich, Ryan F. "Gliding Motility Mechanisms in Divergent Mycoplasma Species". Miami University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1316482073.
Texto completoSuvanasuthi, Rooge. "Genetic determinant of (Silicibacter sp.) TM1040 motility". College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8915.
Texto completoThesis research directed by: Marine, Estuarine, Environmental Sciences Graduate Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
Catlow, Helga Y. "Chemotaxis and motility of Rhizobium trifolii TA1". Thesis, Catlow, Helga Y. (1988) Chemotaxis and motility of Rhizobium trifolii TA1. PhD thesis, Murdoch University, 1988. https://researchrepository.murdoch.edu.au/id/eprint/51979/.
Texto completoDombrowski, Christopher Charles. "Bacterial Motility: From Propulsion to Collective Behavior". Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/195677.
Texto completoCorral, Sábado Jordi. "Implicación de la motilidad en la patogénesis bacteriana". Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/671075.
Texto completoAcinetobacter baumannii y Ralstonia solanacearum son dos especies bacterianas patógenas, filogenéticamente no relacionadas, que en los últimos años han adquirido una gran relevancia debido al impacto sanitario y agroalimentario que, respectivamente, causan en todo el mundo. Por un lado, A. baumannii provoca infecciones nosocomiales que, junto al aumento de cepas multirresistentes, hacen que algunas de estas infecciones sean prácticamente intratables. Por otro lado, R. solanacearum es responsable de la marchitez bacteriana, una enfermedad letal que afecta a más de 200 especies vegetales, disminuyendo la producción de numerosos cultivos de interés para la industria agroalimentaria. Una característica común de ambos microorganismos es su capacidad de moverse. A. baumannii puede desplazarse, en función de la cepa, a través del movimiento asociado a los pili de tipo IV, conocido como twitching; o mediante un movimiento independiente de apéndices denominado surface-associated motility. En el caso de R. solanacearum, esta especie exhibe los movimientos twitching y swimming, este último asociado a flagelos. Al ser la motilidad bacteriana determinante para la virulencia de muchos patógenos, el objetivo global de la presente Tesis Doctoral es la identificación de genes implicados en la motilidad de ambos microorganismos, permitiendo así establecer nuevas dianas terapéuticas. En la cepa de A. baumannii ATCC 17978, capaz de desplazarse exclusivamente mediante surface-associated motility, se evaluó la implicación en este proceso de las proteínas RecA (regulador positivo del sistema SOS) y A1S_2813 (análoga al componente quimiotáctico CheW). Los estudios realizados mostraron que ambas proteínas están involucradas en el surface-associated motility, la respuesta quimiotáctica y la virulencia. Además, estas funciones son llevadas a cabo a través de la interacción específica entre ambas proteínas. Por otro lado, en R. solanacearum GMI1000 se evaluó la función de las proteínas PilI y ChpA, ambas análogas a los componentes del sistema quimiotáctico flagelar CheW y CheA, respectivamente, y a su vez homólogas a componentes del sistema quimiotáctico asociado a pili de tipo IV. Los resultados obtenidos determinaron la implicación de ambas proteínas en la motilidad twitching, la capacidad para incorporar DNA a través de la transformación natural, la formación de biofilm, la adherencia a raíces de tomatera y la virulencia. Paralelamente, los resultados obtenidos con los mutantes deficientes en los genes que codifican las subunidades de pilina (PilA) y flagelina (FliC) permitieron establecer que, PilA está involucrado en la motilidad swimming, mientras que FliC participa en la formación del biofilm y en la adhesión a raíces de tomatera. Los resultados de la presente Tesis Doctoral ponen de manifiesto la importancia de la motilidad bacteriana en el proceso patogénico tanto de A. baumannii como de R. solanacearum, abriendo nuevos frentes de investigación para su utilización como dianas terapéuticas.
Acinetobacter baumannii and Ralstonia solanacearum are two pathogenic bacterial species that, despite not being phylogenetically related, have acquired a great relevance in recent years, due to the sanitary and agri-food impact worldwide, respectively. On the one hand, A. baumannii causes nosocomial infections that, with an increasing number of multidrug resistant strains, some of these infections turn practically intractable. On the other hand, R. solanacearum is responsible of bacterial wilt, a devastating disease that affects more than 200 plant species, decreasing the production of many crops of interest for the agri-food industry. A common characteristic of both microorganisms is their ability to move. A. baumannii is able to move through type IV pili-associated motility called twitching, or by using an appendage-independent movement known as surface-associated motility. In the case of R. solanacearum, this species exhibits twitching and the flagella-associated motility called swimming. As bacterial motility is a determinant factor for the virulence of many pathogens, the main objective of this Doctoral Thesis is the identification of novel genes involved in the motility of both pathogens, which might allow the identification of therapeutic targets. In A. baumannii strain ATCC 17978, which is able to move exclusively through surface-associated motility, the involvement in motility of the RecA (positive regulator of the SOS system) and the A1S_2813 (analogous to the CheW chemotactic component) proteins was evaluated. Results obtained revealed that both proteins are involved in surface-associated motility, the chemotactic response and virulence. Furthermore, these functions are carried out through the specific interaction between both proteins. On the other hand, in R. solanacearum strain GMI1000, the function of the PilI and ChpA proteins, both analogous to the CheW and CheA components of the flagellar-chemotactic system, respectively, and homologous to components of the type IV pili-associated chemotactic system, was evaluated. Results obtained determined the involvement of both proteins in twitching motility, the ability to transform DNA naturally, the biofilm formation, the root attachment and the virulence. Simultaneously, analysis of the mutants deficient for the genes encoding the pilin (PilA) and flagellin (FliC) subunits showed that, while PilA is involved in swimming motility, FliC participates in the biofilm formation and tomato-root attachment processes. The results of this Doctoral Thesis demonstrate the importance of bacterial motility in the pathogenic process of both A. baumannii and R. solanacearum. Furthermore, the identification of new genes involved in the described systems opens up new research fronts for their usage as therapeutic targets.
Universitat Autònoma de Barcelona. Programa de Doctorat en Microbiologia
Zhang, Yong. "Spatial regulation of motility in the social bacterium Myxococcus xanthus". Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX22110.
Texto completoAll organisms, animals, plants and microbes, are composed of polarized cells, displaying asymmetric positioning of sub-cellular organelles or structures. Polarity control has been studied in eukaryotes for a long time, and has been shown to be involved in many physiological processes, such as embryogenesis, cancer metastasis and neuron degenerative diseases. In prokaryotes, polarity studies only emerged recently with the development of sensitive fluorescent microscopy. These studies revealed that prokaryotic cells are in fact highly organized and a growing body of literature has shown that bacterial cells also use lipid rafts, membrane curvature, the cell wall and a complex cytoskeleton to direct the specific positioning of subcellular structures.Small GTPases of the Ras superfamily are widespread polarization regulatory elements in eukaryotes. Despite the long known existence of such small GTPases in prokaryotic genomes, their function has never been studied. During this thesis work, we found, for the first time, that a small GTPase, MglA and its cognate GTPase Activating Protein (GAP) MglB, direct a dynamic anterior- posterior axis to direct motility of the rod-shaped deltaproteobacterium Myxococcus xanthus. In this process, MglA accumulates in its GTP-bound state at the leading cell pole, activating the motility machineries. This localization pattern is maintained by MglB, which localizes at the opposite pole, blocking MglA accumulation at this pole through its GAP activity. Remarkably, both proteins switch their localization synchronously, which correlates with a dramatic change in the direction of cell movement (reversal). This switch is regulated by a chemosensory-like system, Frz. In a second part of this work, we identified a response regulator protein, RomR which is essential for the polar clustering of MglA. Intricate localization interdependencies between Romr, MglA and MglB indicate that these proteins might constitute a dynamic three-protein polarity complex that receives Frz-signaling to switch the polarity axis. In conclusion, the results from this thesis work suggest that M. xanthus integrated a eukaryotic-like polarity module (MglAB) into a prokaryotic- specific (Frz) signaling network to regulate its motility. Such regulation is distinct form small G- protein regulations, which are generally coupled to G-protein coupled receptors (GPCRs) in eukaryotes. Finally, this work paves the way to understand how single cell motility regulations are integrated to generate ordered multicellular behaviors giving rise to primitive developmental structures, for example fruiting body morphogenesis. On the other hand, this work also provides an example to analyze the evolutionary steps giving rise to signaling networks
HIRNING, LANE DURAND. "MULTIPLE PEPTIDE RECEPTORS AND SITES OF ACTION IN THE CANINE SMALL INTESTINE (OPIOIDS, MOTILIN, TACHYKININS, INTESTINAL MOTILITY, SUBSTANCE P)". Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/188150.
Texto completoLeech, Andrew James. "The role of ChpA in Pseudomonas aeruginosa motility /". [St. Lucia, Qld.], 2003. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18369.pdf.
Texto completoMrkonjić, Sanela 1983. "TRPV4 channel regulation and involvement in cell motility". Doctoral thesis, Universitat Pompeu Fabra, 2014. http://hdl.handle.net/10803/300754.
Texto completoEl canal TRPV4 es un canal catiónico capaz de generar señales intracelulares de Ca2+ en diversos tejidos. La participación del canal TRPV4 en procesos de mecano-osmotransducción le implica en funciones tan importantes como la regulación del volumen celular y sistémico. El TRPV4 también se activa en respuesta a calor y al agonista sintético 4αPDD, lo que implica la presencia de varios modos de activación. Además, existen numerosas mutaciones en el TRPV4 que se han encontrado en pacientes que sufren de patología osteoarticular y neuromuscular. Sin embargo, aún se desconocen aspectos de su función relacionados con los mecanismos de activación. Mi trabajo de Tesis doctoral aborda el estudio de la región N-terminal del TRPV4, su participación en la activación del canal por estímulos fisiológicos y la relevancia del canal en proceso de migración celular. Esta Tesis doctoral proporciona evidencias de que el TRPV4 necesita unir PIP2 a través de la secuencia 121KRWRK125 de la cola N-terminal y que las colas se reorganicen para que el canal se abra en respuesta a estímulos osmóticos y de calor. Mis estudios también sugieren que el canal TRPV4 participa en la modulación de la adherencia de la cola durante el proceso de la migración celular, posiblemente interaccionando con otros canales presentes en las adhesiones focales.
Sroka, Thomas Charles. "Synthetic Peptide Ligand Mimetics and Tumor Cell Motility". Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1325%5F1%5Fm.pdf&type=application/pdf.
Texto completoRader, Bethany Anne. "Autoinducer-2 regulation of motility in Helicobacter pylori /". view abstract or download file of text, 2006. http://proquest.umi.com/pqdweb?did=1251819321&sid=6&Fmt=2&clientId=11238&RQT=309&VName=PQD.
Texto completoTypescript. Includes vita and abstract. Includes bibliographical references (leaves 80 - 90). Also available for download via the World Wide Web; free to University of Oregon users.
Kjellin, Ann. "Foregut motility disorders : a clinical and experimental study /". Stockholm, 2004. http://diss.kib.ki.se/2004/91-7140-026-5/.
Texto completoLiu, Zhiwen. "Matrix metalloproteases and cell motility in malignant mesothelioma /". Stockholm, 2004. http://diss.kib.ki.se/2004/91-7140-061-3/.
Texto completoKotha, Jayaprakash. "Molecular mechanism of tetraspanin CD9 mediated cell motility". View the abstract Download the full-text PDF version, 2007. http://etd.utmem.edu/ABSTRACTS/2007-010-Kotha-index.html.
Texto completoTitle from title page screen (viewed on July 16, 2007). Research advisor: Lisa K. Jennings, Ph.D. Document formatted into pages (xiv, 150 p. : ill.). Vita. Abstract. Includes bibliographical references (p.130-150).
Fuhs, Thomas. "Intracellular polymer network as source od cell motility". Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-124097.
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