Bibliographies thématiques / Microtubules dynamics

Littérature scientifique sur le sujet « Microtubules dynamics »

Auteur : Grafiati

Publié le 11 mars 2023

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Articles de revues sur le sujet "Microtubules dynamics"

Zwetsloot, Alexander James, Gokhan Tut et Anne Straube. « Measuring microtubule dynamics ». Essays in Biochemistry 62, n^o 6 (4 octobre 2018) : 725–35. http://dx.doi.org/10.1042/ebc20180035.

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Microtubules are key players in cellular self-organization, acting as structural scaffolds, cellular highways, force generators and signalling platforms. Microtubules are polar filaments that undergo dynamic instability, i.e. transition between phases of growth and shrinkage. This allows microtubules to explore the inner space of the cell, generate pushing and pulling forces and remodel themselves into arrays with different geometry and function such as the mitotic spindle. To do this, eukaryotic cells employ an arsenal of regulatory proteins to control microtubule dynamics spatially and temporally. Plants and microorganisms have developed secondary metabolites that perturb microtubule dynamics, many of which are in active use as cancer chemotherapeutics and anti-inflammatory drugs. Here, we summarize the methods used to visualize microtubules and to measure the parameters of dynamic instability to study both microtubule regulatory proteins and the action of small molecules interfering with microtubule assembly and/or disassembly.

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Vemu, Annapurna, Joseph Atherton, Jeffrey O. Spector, Carolyn A. Moores et Antonina Roll-Mecak. « Tubulin isoform composition tunes microtubule dynamics ». Molecular Biology of the Cell 28, n^o 25 (décembre 2017) : 3564–72. http://dx.doi.org/10.1091/mbc.e17-02-0124.

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Microtubules polymerize and depolymerize stochastically, a behavior essential for cell division, motility, and differentiation. While many studies advanced our understanding of how microtubule-associated proteins tune microtubule dynamics in trans, we have yet to understand how tubulin genetic diversity regulates microtubule functions. The majority of in vitro dynamics studies are performed with tubulin purified from brain tissue. This preparation is not representative of tubulin found in many cell types. Here we report the 4.2-Å cryo-electron microscopy (cryo-EM) structure and in vitro dynamics parameters of α1B/βI+βIVb microtubules assembled from tubulin purified from a human embryonic kidney cell line with isoform composition characteristic of fibroblasts and many immortalized cell lines. We find that these microtubules grow faster and transition to depolymerization less frequently compared with brain microtubules. Cryo-EM reveals that the dynamic ends of α1B/βI+βIVb microtubules are less tapered and that these tubulin heterodimers display lower curvatures. Interestingly, analysis of EB1 distributions at dynamic ends suggests no differences in GTP cap sizes. Last, we show that the addition of recombinant α1A/βIII tubulin, a neuronal isotype overexpressed in many tumors, proportionally tunes the dynamics of α1B/βI+βIVb microtubules. Our study is an important step toward understanding how tubulin isoform composition tunes microtubule dynamics.

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Parker, Amelia L., Wee Siang Teo, Elvis Pandzic, Juan Jesus Vicente, Joshua A. McCarroll, Linda Wordeman et Maria Kavallaris. « β-Tubulin carboxy-terminal tails exhibit isotype-specific effects on microtubule dynamics in human gene-edited cells ». Life Science Alliance 1, n^o 2 (19 avril 2018) : e201800059. http://dx.doi.org/10.26508/lsa.201800059.

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Microtubules are highly dynamic structures that play an integral role in fundamental cellular functions. Different α- and β-tubulin isotypes are thought to confer unique dynamic properties to microtubules. The tubulin isotypes have highly conserved structures, differing mainly in their carboxy-terminal (C-terminal) tail sequences. However, little is known about the importance of the C-terminal tail in regulating and coordinating microtubule dynamics. We developed syngeneic human cell models using gene editing to precisely modify the β-tubulin C-terminal tail region while preserving the endogenous microtubule network. Fluorescent microscopy of live cells, coupled with advanced image analysis, revealed that the β-tubulin C-terminal tails differentially coordinate the collective and individual dynamic behavior of microtubules by affecting microtubule growth rates and explorative microtubule assembly in an isotype-specific manner. Furthermore, βI- and βIII-tubulin C-terminal tails differentially regulate the sensitivity of microtubules to tubulin-binding agents and the microtubule depolymerizing protein mitotic centromere-associated kinesin. The sequence of the β-tubulin tail encodes regulatory information that instructs and coordinates microtubule dynamics, thereby fine-tuning microtubule dynamics to support cellular functions.

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Gupta, Mohan L., Claudia J. Bode, Douglas A. Thrower, Chad G. Pearson, Kathy A. Suprenant, Kerry S. Bloom et Richard H. Himes. « β-Tubulin C354 Mutations that Severely Decrease Microtubule Dynamics Do Not Prevent Nuclear Migration in Yeast ». Molecular Biology of the Cell 13, n^o 8 (août 2002) : 2919–32. http://dx.doi.org/10.1091/mbc.e02-01-0003.

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Microtubule dynamics are influenced by interactions of microtubules with cellular factors and by changes in the primary sequence of the tubulin molecule. Mutations of yeast β-tubulin C354, which is located near the binding site of some antimitotic compounds, reduce microtubule dynamicity greater than 90% in vivo and in vitro. The resulting intrinsically stable microtubules allowed us to determine which, if any, cellular processes are dependent on dynamic microtubules. The average number of cytoplasmic microtubules decreased from 3 in wild-type to 1 in mutant cells. The single microtubule effectively located the bud site before bud emergence. Although spindles were positioned near the bud neck at the onset of anaphase, the mutant cells were deficient in preanaphase spindle alignment along the mother-bud axis. Spindle microtubule dynamics and spindle elongation rates were also severely depressed in the mutants. The pattern and extent of cytoplasmic microtubule dynamics modulation through the cell cycle may reveal the minimum dynamic properties required to support growth. The ability to alter intrinsic microtubule dynamics and determine the in vivo phenotype of cells expressing the mutant tubulin provides a critical advance in assessing the dynamic requirements of an essential gene function.

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Rodionov, V. I., S. S. Lim, V. I. Gelfand et G. G. Borisy. « Microtubule dynamics in fish melanophores. » Journal of Cell Biology 126, n^o 6 (15 septembre 1994) : 1455–64. http://dx.doi.org/10.1083/jcb.126.6.1455.

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We have studied the dynamics of microtubules in black tetra (Gymnocorymbus ternetzi) melanophores to test the possible correlation of microtubule stability and intracellular particle transport. X-rhodamine-or caged fluorescein-conjugated tubulin were microinjected and visualized by fluorescence digital imaging using a cooled charge coupled device and videomicroscopy. Microtubule dynamics were evaluated by determining the time course of tubulin incorporation after pulse injection, by time lapse observation, and by quantitation of fluorescence redistribution after photobleaching and photoactivation. The time course experiments showed that the kinetics of incorporation of labeled tubulin into microtubules were similar for cells with aggregated or dispersed pigment with most microtubules becoming fully labeled within 15-20 min after injection. Quantitation by fluorescence redistribution after photobleaching and photoactivation confirmed that microtubule turnover was rapid in both states, t1/2 = 3.5 +/- 1.5 and 6.1 +/- 3.0 min for cells with aggregated and dispersed pigment, respectively. In addition, immunostaining with antibodies specific to posttranslationally modified alpha-tubulin, which is usually enriched in stable microtubules, showed that microtubules composed exclusively of detyrosinated tubulin were absent and microtubules containing acetylated tubulin were sparse. We conclude that the microtubules of melanophores are very dynamic, that their dynamic properties do not depend critically on the state of pigment distribution, and that their stabilization is not a prerequisite for intracellular transport.

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Vorobjev, I. A., T. M. Svitkina et G. G. Borisy. « Cytoplasmic assembly of microtubules in cultured cells ». Journal of Cell Science 110, n^o 21 (1 novembre 1997) : 2635–45. http://dx.doi.org/10.1242/jcs.110.21.2635.

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The origin of non-centrosomal microtubules was investigated in a variety of animal cells in culture by means of time-lapse digital fluorescence microscopy. A previous study (Keating et al. (1997) Proc. Nat. Acad. Sci. USA 94, 5078–5083) demonstrated a pathway for formation of non-centrosomal microtubules by release from the centrosome. Here we show a parallel pathway not dependent upon the centrosome. Correlative immunostaining with anti-tubulin antibodies and electron microscopy established that apparent free microtubules observed in vivo were not growing ends of long stable microtubules. Free microtubules appeared spontaneously in the cytoplasm and occasionally by breakage of long microtubules. Estimates of the frequencies of free microtubule formation suggest that it can be a relatively common rather than exceptional event in PtK1 cells and may represent a significant source of non-centrosomal microtubules. The observation of free microtubules permitted analysis of the microtubule minus end. Unlike the plus end which showed dynamic instability, the minus end was stable or depolymerized. Breakage of long microtubules generated nascent plus and minus ends; the nascent minus end was generally stable while the plus end was always dynamic. The stability of microtubule minus ends in vivo apparently provides the necessary condition for free microtubule formation in the cytoplasm. Parameters of the dynamic instability of plus ends of free microtubules were similar to those for the distal ends of long microtubules, indicating that the free microtubules were not exceptional in their dynamic behavior. Random walk analysis of microtubule end dynamics gave apparent diffusion coefficients for free and long microtubules which permitted an estimate of turnover half-times. The results support the concept that, in PtK1 cells, a pathway other than plus end dynamics is needed to account for the rapidity of microtubule turnover.

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Cassimeris, L. U., P. Wadsworth et E. D. Salmon. « Dynamics of microtubule depolymerization in monocytes. » Journal of Cell Biology 102, n^o 6 (1 juin 1986) : 2023–32. http://dx.doi.org/10.1083/jcb.102.6.2023.

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Human monocytes, which contain few interphase microtubules (35.+/- 7.7), were used to study the dynamics of microtubule depolymerization. Steady-state microtubule assembly was abruptly blocked with either high concentrations of nocodazole (10 micrograms/ml) or exposure to cold temperature (3 degrees C). At various times after inhibition of assembly, cells were processed for anti-tubulin immunofluorescence microscopy. Stained cells were observed with an intensified video camera attached to the fluorescence microscope. A tracing of the entire length of each individual microtubule was made from the image on the television monitor by focusing up and down through the cell. The tracings were then digitized into a computer. All microtubules were seen to originate from the centrosome, with an average length in control cells of 7.1 +/- 2.7 microns (n = 957 microtubules). During depolymerization, the total microtubule polymer and the number of microtubules per cell decreased rapidly. In contrast, there was a slow decrease in the average length of the persisting microtubules. The half-time for both the loss of total microtubule polymer and microtubule number per cell was approximately 40 s for nocodazole-treated cells. The rate-limiting step in the depolymerization process was the rate of initiation of disassembly. Once initiated, depolymerization appeared catastrophic. Further kinetic analysis revealed two classes of microtubules: 70% of the microtubule population was very labile and initiated depolymerization at a rate approximately 23 times faster than a minor population of persistent microtubules. Cold treatment yielded qualitatively similar characteristics of depolymerization, but the initiation rates were slower. In both cases there was a significant asynchrony and heterogeneity in the initiation of depolymerization among the population of microtubules.

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Kosco, Karena A., Chad G. Pearson, Paul S. Maddox, Peijing Jeremy Wang, Ian R. Adams, E. D. Salmon, Kerry Bloom et Tim C. Huffaker. « Control of Microtubule Dynamics by Stu2p Is Essential for Spindle Orientation and Metaphase Chromosome Alignment in Yeast ». Molecular Biology of the Cell 12, n^o 9 (septembre 2001) : 2870–80. http://dx.doi.org/10.1091/mbc.12.9.2870.

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Stu2p is a member of a conserved family of microtubule-binding proteins and an essential protein in yeast. Here, we report the first in vivo analysis of microtubule dynamics in cells lacking a member of this protein family. For these studies, we have used a conditional Stu2p depletion strain expressing α-tubulin fused to green fluorescent protein. Depletion of Stu2p leads to fewer and less dynamic cytoplasmic microtubules in both G1 and preanaphase cells. The reduction in cytoplasmic microtubule dynamics is due primarily to decreases in both the catastrophe and rescue frequencies and an increase in the fraction of time microtubules spend pausing. These changes have significant consequences for the cell because they impede the ability of cytoplasmic microtubules to orient the spindle. In addition, recovery of fluorescence after photobleaching indicates that kinetochore microtubules are no longer dynamic in the absence of Stu2p. This deficiency is correlated with a failure to properly align chromosomes at metaphase. Overall, we provide evidence that Stu2p promotes the dynamics of microtubule plus-ends in vivo and that these dynamics are critical for microtubule interactions with kinetochores and cortical sites in the cytoplasm.

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Hyman, A. A., et T. J. Mitchison. « Modulation of microtubule stability by kinetochores in vitro. » Journal of Cell Biology 110, n^o 5 (1 mai 1990) : 1607–16. http://dx.doi.org/10.1083/jcb.110.5.1607.

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The interface between kinetochores and microtubules in the mitotic spindle is known to be dynamic. Kinetochore microtubules can both polymerize and depolymerize, and their dynamic behavior is intimately related to chromosome movement. In this paper we investigate the influence of kinetochores on the inherent dynamic behavior of microtubules using an in vitro assay. The dynamics of microtubule plus ends attached to kinetochores are compared to those of free plus ends in the same solution. We show that microtubules attached to kinetochores exhibit the full range of dynamic instability behavior, but at altered transition rates. Surprisingly, we find that kinetochores increase the rate at which microtubule ends transit from growing to shrinking. This result contradicts our previous findings (Mitchison, T. J., and M. W. Kirschner, 1985b) for technical reasons which are discussed. We suggest that catalysis of the growing to shrinking transition by kinetochores may account for selective depolymerization of kinetochore microtubules during anaphase in vivo. We also investigate the effects of a nonhydrolyzable ATP analogue on kinetochore microtubule dynamics. We find that 5' adenylylimido diphosphate induces a rigor state at the kinetochore-microtubule interface, which prevents depolymerization of the microtubule.

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Warren, James C., Adam Rutkowski et Lynne Cassimeris. « Infection with Replication-deficient Adenovirus Induces Changes in the Dynamic Instability of Host Cell Microtubules ». Molecular Biology of the Cell 17, n^o 8 (août 2006) : 3557–68. http://dx.doi.org/10.1091/mbc.e05-09-0850.

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Adenovirus translocation to the nucleus occurs through a well characterized minus end-directed transport along microtubules. Here, we show that the adenovirus infection process has a significant impact on the stability and dynamic behavior of host cell microtubules. Adenovirus-infected cells had elevated levels of acetylated and detyrosinated microtubules compared with uninfected cells. The accumulation of modified microtubules within adenovirus-infected cells required active RhoA. Adenovirus-induced changes in microtubule dynamics were characterized at the centrosome and at the cell periphery in living cells. Adenovirus infection resulted in a transient enhancement of centrosomal microtubule nucleation frequency. At the periphery of adenovirus-infected cells, the dynamic instability of microtubules plus ends shifted toward net growth, compared with the nearly balanced growth and shortening observed in uninfected cells. In infected cells, microtubules spent more time in growth, less time in shortening, and underwent catastrophes less frequently compared with those in uninfected cells. Drug-induced inhibition of Rac1 prevented most of these virus-induced shifts in microtubule dynamic instability. These results demonstrate that adenovirus infection induces a significant stabilizing effect on host cell microtubule dynamics, which involve, but are not limited to, the activation of the RhoGTPases RhoA and Rac1.

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Thèses sur le sujet "Microtubules dynamics"

Schaedel, Laura. « Les propriétés mécaniques des microtubules ». Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY010/document.

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Les microtubules-qui définissent la forme des axones, des cils et des flagelles, et qui servent de rails pour le transport intracellulaire-subissent de fortes contraintes exercées par les forces intracellulaires. La structure des microtubules et leur rigiditépeuvent en théorie être affectées par des contraintes physiques. Cependant, il reste à établir comment les microtubules tolèrent de telles forces et quelles sont les conséquences de ces forces sur la structure des microtubules. En utilisant un dispositif demicrofluidique, j’ai pu montrer que la rigidité des microtubules diminue progressivementà chaque cycle de courbure induit par des contraintes hydrodynamiques.Comme dans d'autres exemples de fatigue des matériaux, l'application de contraintes mécaniques sur des défauts pré-existants le long des microtubules est responsable de la génération de dommages plus étendus. Ce processus rend les microtubules moins rigides.J’ai pu aussi montrer que les microtubules endommagés peuvent se réparer en intégrant de nouveaux dimères de tubuline à leur surface et de récupérer ainsi leur rigidité initiale. Nos résultats démontrent que les microtubules sont des matériaux biologiquesayant des propriétés d’auto-réparation, et que la dynamique des microtubules ne se produit pas exclusivement à leurs extrémités. La mise en évidence de ces nouvelles propriétés permet de montrer comment les microtubules peuvent s’adapter à des contraintesmécaniques
Microtubules—which define the shape of axons, cilia and flagella, and provide tracks for intracellular transport—can be highly bent by intracellular forces, and microtubule structure and stiffness are thought to be affected by physical constraints. Yet how microtubules tolerate the vast forces exerted on them remains unknown. Here, by using a microfluidic device, we show that microtubule stiffness decreases incrementally with each cycle of bending and release. Similar to other cases of material fatigue, the concentration of mechanical stresses on pre-existing defects in the microtubule lattice is responsible for the generation of more extensive damage, which further decreases microtubule stiffness. Strikingly, damaged microtubules were able to incorporate new tubulin dimers into their lattice and recover their initial stiffness. Our findings demonstrate that microtubules are ductile materials with self-healing properties, that their dynamics does not exclusively occur at their ends, and that their lattice plasticity enables the microtubules’ adaptation to mechanical stresses

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A, S. Jijumon. « Systematic characterization of a large number of Microtubule-Associated Proteins using purification-free TIRF-reconstitution assays Purification of tubulin with controlled post-translational modifications by polymerization–depolymerization cycles Microtubule-Associated Proteins : Structuring the Cytoskeleton Purification of custom modified tubulin from cell lines and mouse brains by polymerization-depolymerization cycles ». Thesis, université Paris-Saclay, 2021. http://www.theses.fr/2021UPASL007.

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Le cytosquelette des microtubules (MTs) est constitué de filaments dynamiques impliqués dans une multitude de fonctions telles que la division cellulaire, le maintien de forme des cellules, les battements ciliaires ou encore la différenciation neuronale. Une régulation stricte des fonctions des MTs est donc d'une grande importance pour l'homéostasie cellulaire, et toute perturbation pourrait potentiellement conduire à des maladies comme le cancer, les ciliopathies ou la neurodégénérescence. Dans un contexte cellulaire, les propriétés des MTs peuvent être contrôlées par leurs interactions avec une grande variété de protéines associées (MT-associated proteins ; MAPs). Notre connaissance de ces interacteurs s'est continuellement enrichie au cours des dernières décennies, mais il n'existe à ce jour aucune étude systématique visant à décrire et à classer ces protéines en fonction de leurs mécanismes de liaison et de leurs effets structuraux sur les MTs. Dans mon projet de thèse, j’ai mis au point un essai permettant une analyse rapide et systématique à la base des lysats clarifiés de cellules humaines surexprimant une multitude des différents MAPs. Le comportement dynamique des MT en présence d'environ 50 MAPs différentes a été imagé à l'aide de la microscopie TIRF. Cela nous permet d'étudier le comportement des MAP dans une situation proche de leur environnement naturel, mais en éliminant la complexité de l'espace intracellulaire, telle que l'encombrement par des organelles et des filaments du cytosquelette à l'intérieur de l'espace intracellulaire confiné. En effet, la plupart des MAPs étaient bien solubles dans notre approche d'extraction, tandis que les approches de purification pour plusieurs d'entre elles ont conduit à leur précipitation, rendent les expériences de reconstitution in vitro classique impossible. Ma nouvelle approche m’a permis de définir plusieurs nouvelles protéines comme de véritables MAP. J’ai montré que des MAPs non-caractérisées auparavant ont des effets étonnamment différents sur la polymérisation et la structure des MTs, créant ainsi une variété de réseaux de MT distincts. J’ai également démontré que mon approche permet d'étudier les structures des MAPs associées aux MTs par cryo-microscopie électronique, ou d'étudier le dynamique des MTs porteuses de mutations trouvées dans les pathologies humaines. J’ai également démontré que mon approche permet à tester la sensibilité des MAPs aux modifications post-traductionnelles de la tubuline, ou d'étudier le rôle des MAPs dans les interactions entre l'actine et les MTs. Mon approche expérimentale permet donc de mieux comprendre comment les MAP et les MT contrôlent ensemble le fonctionnement du cytosquelette
Microtubules (MTs) are dynamic filaments involved in a plethora of functions such as cell division, cell shape, ciliary beating, neuronal differentiation. Strict regulation of MT functions is therefore of high importance for the cellular homeostasis, and any perturbations could potentially lead to diseases like cancer, ciliopathies and neurodegeneration. At the protein level, there are accumulating studies showing that MT properties can be controlled via interaction with a large variety of MT-associated proteins (MAPs). Our knowledge of MAPs has been enriched over time, but up to this date no systematic studies exist that aim to describe and categorize these proteins according to their binding mechanisms and structural effects on MTs. In my PhD project, I have developed an assay for rapid and systematic analysis of MAPs using cleared lysates of cultured human cells in which I overexpress a variety of different MAPs. The dynamic behaviour of growing MTs in the presence of those MAPs were imaged using TIRF microscopy. This allows me to study the behaviour of around 50 MAP candidates in a situation close to their natural environment, but eliminating complexity coming from different organelles and crammed cytoskeleton filaments inside the confined intracellular space. Indeed, most MAPs were nicely soluble in the extract approach, while purification attempts of several of them led to protein precipitation, thus making classical invitro reconstitution approaches impossible. This novel approach allowed me to compare many MAPs under similar experimental conditions, and helped to define several novel proteins as bona-fide MAPs. I demonstrate that previously uncharacterized MAPs have strikingly different effects on MT polymerization and MT structure, thus creating a variety of distinct MT arrays. I further extended this cell-free pipeline to study structures of MAPs bound to MTs by cryo-electron microscopy, or to study the MT interactions of MAPs carrying patient mutations. Finally, I demonstrated that my approach can be used to test the sensitivity of MAPs to tubulin PTMs, as well as to study the role of MAPs in actin-MT crosstalk. In the future, this novel approach will allow for a better mechanistic understanding of how MAPs and MTs together control cytoskeleton functions

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Jiang, Nan. « Exploring Microtubule Structural Mechanics through Molecular Dynamics Simulations ». University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504878667194719.

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Melbinger, Anna Tatjana. « On the role of fluctuations in evolutionary dynamics and transport on microtubules ». Diss., Ludwig-Maximilians-Universität München, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-148246.

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Swoger, Maxx Ryan. « Computational Investigation of Material and Dynamic Properties of Microtubules ». University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1532108320185937.

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Paulin-Levasseur, Micheline. « Cellular dynamics of vimentin filaments and their spatial relationship to microtubules in lymphocytes ». Thesis, University of Ottawa (Canada), 1987. http://hdl.handle.net/10393/5396.

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Sousa, Da Costa Maria Judite. « Csi2 modulates microtubule dynamics and helps organize the bipolar spindle for proper chromosome segregation in fission yeast ». Paris 6, 2013. http://www.theses.fr/2013PA066626.

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Proper chromosome segregation is of paramount importance for proper genetic inheritance. Defects in chromosome segregation can lead to aneuploidy, which is a hallmark of cancer cells. Eukaryotic chromosome segregation is accomplished by the bipolar spindle. Additional mechanisms such as the spindle assembly checkpoint and centromere positioning further help to ensure complete segregation fidelity. We present here the fission yeast csi2+. Csi2p localizes to the spindle poles, where it regulates mitotic microtubule dynamics, bipolar spindle formation, and subsequent chromosome segregation. The bipolar mitotic spindle contains many short dynamic microtubules of ~1 micron scale, this represents a challenge for live cell imaging because the typical maximum resolution of the optical microscope is ~λ/2 or ~300 nm. We developed a novel method to image short fission yeast mitotic microtubules using the thermosensitive reversible kinesin-5 cut7. 24ts to create monopolar spindles. Csi2-deletion (csi2Δ) results in abnormally long mitotic microtubules, high rate of transient monopolar spindles, and a subsequent high rate of chromosome segregation defects. As csi2Δ has multiple phenotypes, it enables estimates of the relative contribution of the different mechanisms to the overall chromosome segregation process. Centromere positioning, microtubule dynamics, and bipolar spindle formation can all contribute to chromosome segregation. Our data suggests that the major determinant of chromosome segregation defects may be microtubule dynamic defects
La ségrégation correcte des chromosomes est processus fondamental pour maintenir la stabilité génomique. Des défauts de ségrégation sont souvent à l’origine de l’apparition de cellules aneuploïdes, caractéristique fréquemment observée dans les cellules cancéreuses. Dans les cellules eucaryotes, la ségrégation correcte des chromosomes est assurée par le fuseau mitotique. Des mécanismes de contrôle, tels que le point de contrôle mitotique et le bon attachement des centromères, sont mis en œuvre pour assurer la bonne ségrégation des chromosomes. Dans cette étude, nous avons pu établir chez le levure fissipare, que la protéine csi2, localisée aux pôles du fuseau mitotique, joue un rôle sur la dynamique des MTs mitotiques, dans la formation d’un fuseau mitotique intègre et par conséquent dans la ségrégation correcte des chromosomes. Les MTs composants le fuseau mitotique bipolaire sont dynamiques et de petite taille ~1µm ce qui représente un défis technique pour les imager, en effet, la résolution optique d’un microscope ~λ/2 est en général de 300nm. Nous avons développé une nouvelle approche pour imager les MTs mitotiques basée sur l’utilisation du mutant réversible thermosensible kinesin-5 cut7. 24ts, pour obtenir des cellules ayant des fuseaux monopolaires. Ainsi, nous avons pu mettre en évidence que la délétion de la protéine csi2 chez la levure S. Pombe était à l’origine d’un allongement de la longueur des microtubules mitotiques, d’une augmentation du nombre de cellules présentant un fuseau monopolaire et d’une augmentation des défauts de ségrégation des chromosomes. L’étude de l’implication de la protéine csi2 dans ces différents mécanismes nous a permis de mettre en évidence la contribution de chacun de ces mécanismes dans la bonne ségrégation des chromosomes. Nous proposons dans cette étude que le facteur déterminant à l’origine d’une ségrégation incorrecte des chromosomes serait majoritairement imputable à des défauts de régulation de la dynamique des microtubules

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Ng, Daniel. « Investigating the dynamics of adhesion complex turnover by mass spectrometry based proteomics ». Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/investigating-the-dynamics-of-adhesion-complex-turnover-by-mass-spectrometry-based-proteomics(4e6d3051-c007-4715-a290-9acfd45d38a7).html.

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Adhesion complexes (ACs) are large macromolecular complexes of integrins and associated proteins that connect the actin cytoskeleton to the extracellular matrix. In migrating cells, ACs are highly dynamic -- forming and maturing at the cell front and disassembling at the cell rear. The turnover of ACs enables and localises the necessary traction forces required for cell migration. There is evidence for the spatiotemporal recruitment of specific proteins during AC maturation or disassembly; however, a holistic understanding of the compositional changes to ACs during these states is lacking. To this end, we sought to characterise the dynamic changes that occur at ACs during turnover using a mass spectrometry (MS)-based proteomics approach. A major challenge in studying AC turnover is the desynchronised nature of AC formation, maturation and disassembly within a population of cells. Therefore a nocodazole-washout assay was used to synchronise microtubule-induced AC maturation and disassembly. To study the dynamics of AC turnover by MS, an AC isolation method was optimised for use with the nocodazole-washout assay. Subsequently, the maturation of ACs by the loss of microtubules was studied by MS-based proteomics, and it was found that this resulted in the overall accumulation of adhesion proteins, and also the conversion of fibrillar adhesions to focal adhesions. Studying the dynamic process of AC disassembly requires a sensitive MS quantification method; as such, label-free quantitative methods were compared, and it was found that LC-MS peak ion intensity quantification performed better than spectral counting. Using optimised methodologies for isolation of ACs and MS quantification, the dynamics of AC disassembly was analysed over the course of the nocodazole-washout assay. It was found that in general, microtubules were enriched around ACs, whereas many structural AC proteins decreased over time. In summary, we have optimised methods for the study of ACs by MS-based proteomics, and applied these methods to the study of AC turnover.

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Rauch, Philipp. « Neuronal Growth Cone Dynamics ». Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-119885.

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Sensory-motile cells fulfill various biological functions ranging from immune activity or wound healing to the formation of the highly complex nervous systems of vertebrates. In the case of neurons, a dynamic structure at the tip of outgrowing processes navigates towards target cells or areas during the generation of neural networks. These fan shaped growth cones are equipped with a highly complex molecular machinery able to detect various external stimuli and to translate them into directed motion. Receptor and adhesion molecules trigger signaling cascades that regulate the dynamics of an internal polymeric scaffold, the cytoskeleton. It plays a crucial role in morphology maintenance as well as in the generation and distribution of growth cone forces. The two major components, actin and microtubules (MTs) connect on multiple levels through interwoven biochemical and mechanical interactions. Actin monomers assemble into semiflexible filaments (F-actin) which in turn are either arranged in entangled networks in the flat outer region of the growth cone (lamellipodium) or in radial bundles termed filopodia. The dynamic network of actin filaments extends through polymerization at the front edge of the lamellipodium and is simultaneously moving towards the center (C-domain) of the growth cone. This retrograde flow (RF) of the actin network is driven by the polymerizing filaments themselves pushing against the cell membrane and the contractile activity of motor proteins (myosins), mainly in the more central transition zone (T-zone). Through transmembrane adhesion molecules, a fraction of the retrograde flow forces is mechanically transmitted to the cellular substrate in a clutch-like mechanism generating traction and moving the GC forward. MTs are tubular polymeric structures assembled from two types of tubulin protein subunits. They are densely bundled in the neurite and at the growth cone “neck” (where the neurite opens out into the growth cone) they splay apart entering the C-domain and more peripheral regions (P-domain). Their advancement is driven by polymerization and dynein motor protein activity. The two subsystems, an extending array of MTs and the centripetal moving actin network are antagonistic players regulating GC morphology and motility. Numerous experimental findings suggest that MTs pushing from the rear interact with actin structures and contribute to GC advancement. Nevertheless, the amount of force generated or transmitted through these rigid structures has not been investigated yet. In the present dissertation, the deformation of MTs under the influence of intracellular load is analyzed with fluorescence microscopy techniques to estimate these forces. RF mechanically couples to MTs in the GC periphery through friction and molecular cross-linkers. This leads to MT buckling which in turn allows the calculation of the underlying force. It turns out that forces of at least act on individual MT filaments in the GC periphery. Compared to the relatively low overall protrusion force of neuronal GCs, this is a substantial contribution. Interestingly, two populations of MTs buckle under different loads suggesting different buckling conditions. These could be ascribed to either the length-dependent flexural rigidity of MTs or local variations in the mechanical properties of the lamellipodial actin network. Furthermore, the relation between MT deformation levels and GC morphology and advancement was investigated. A clear trend evolves that links higher MT deformation in certain areas to their advancement. Interactions between RF and MTs also influence flow velocity and MT deformation. It is shown that transient RF bursts are related to higher MT deformation in the same region. An internal molecular clutch mechanism is proposed that links MT deformation to GC advancement. When focusing on GC dynamics it is often neglected that the retraction of neurites and the controlled collapse of GCs are as important for proper neural network formation as oriented outgrowth. Since erroneous connections can cause equally severe malfunctions as missing ones, the pruning of aberrant processes or the transient stalling of outgrowth at pivotal locations are common events in neuronal growth. To date, mainly short term pausing with minor cytoskeletal rearrangements or the full detachment and retraction of neurite segments were described. It is likely that these two variants do not cover the full range of possible events during neuronal pathfinding and that pausing on intermediate time scales is an appropriate means to avoid the misdetection of faint or ambiguous external signals. In the NG108-15 neuroblastoma cells investigated here, a novel type of collapse was observed. It is characterized by the degradation of actin network structures in the periphery while radial filopodia and the C-domain persist. Actin bundles in filopodia are segmented at one or multiple breaking points and subsequently fold onto the edge of the C-domain where they form an actin-rich barrier blocking MT extension. Due to this characteristic, this type of collapse was termed fold collapse. Possible molecular players responsible for this remarkable process are discussed. Throughout fold collapse, GC C-domain area and position remain stable and only the turnover of peripheral actin structures is abolished. At the same time, MT driven neurite elongation is hindered, causing the GC to stall on a time scale of several to tens of minutes. In many cases, new lamellipodial structures emerge after some time, indicating the transient nature of this collapse variant. From the detailed description of the cytoskeletal dynamics during collapse a working model including substrate contacts and contractile actin-myosin activity is derived. Within this model, the known and newly found types of GC collapse and retraction can be reduced to variations in local adhesion and motor protein activity. Altogether the results of this work indicate a more prominent role of forward directed MT-based forces in neuronal growth than previously assumed. Their regulation and distribution during outgrowth has significant impact on neurite orientation and advancement. The deformation of MT filaments is closely related to retrograde actin flow which in turn is a regulator of edge protrusion. For the stalling of GCs it is not only required that actin dynamics are decoupled from the environment but also that MT pushing is suppressed. In the case of fold collapse, this is achieved through a robust barrier assembled from filopodial actin bundles.

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Shukla, Nandini Y. « Investigation of Microtubule dynamics and novel Microtubule-associated proteins in growth and development of the filamentous fungus, Aspergillus nidulans ». The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu149276142029341.

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Livres sur le sujet "Microtubules dynamics"

Microtubule dynamics : Methods and protocols. New York : Humana, 2011.

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Straube, Anne, dir. Microtubule Dynamics. Totowa, NJ : Humana Press, 2011. http://dx.doi.org/10.1007/978-1-61779-252-6.

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1937-, Soifer David, dir. Dynamic aspects of microtubule biology. New York, N.Y : New York Academy of Sciences, 1986.

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Qu, Xiaoyi. Microtubule Dynamics in Tau-dependent Amyloid Beta Synaptotoxicity. [New York, N.Y.?] : [publisher not identified], 2019.

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Lamb, Jeremy Charles. Fluorescent derivatives of tubulin as probes for the analysis of microtubule dynamics. Norwich : University of East Anglia, 1985.

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Böhlke, Christopher. Kif3a guides microtubular dynamics, migration and lumen formation of MDCK cells. Freiburg : Universität, 2013.

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Mathew, Shyno. Molecular Dynamics Simulations of Microtubule-associated protein 1A/1B-light chain 3 (LC3) and its membrane associated form(LC3-II). [New York, N.Y.?] : [publisher not identified], 2017.

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Straube, Anne. Microtubule Dynamics : Methods and Protocols. Humana Press, 2017.

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Mikhailov, Alexei. The dynamics and interactions of microtubules in locomoting fibroblasts. 1998.

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Warner, Fred D., et J. Richard McIntosh. Cell Movement Vol. II : Kinesin, Dynein, and Microtubule Dynamics. Wiley & Sons, Incorporated, John, 1989.

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Chapitres de livres sur le sujet "Microtubules dynamics"

Zdravković, Slobodan. « Nonlinear Dynamics of Microtubules ». Dans Nonlinear Dynamics of Nanobiophysics, 263–305. Singapore : Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-5323-1_10.

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Carlier, Marie-France, Ronald Melki, Cécile Combeau et D. Pantaloni. « Phosphate Release Following Nucleotide Hydrolysis Regulates the Dynamics of Actin Filaments and Microtubules ». Dans Springer Series in Biophysics, 264–67. Berlin, Heidelberg : Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-73925-5_48.

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Flyvbjerg, Henrik. « Microtubule Dynamics ». Dans Physics of Biological Systems, 213–30. Berlin, Heidelberg : Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-540-49733-2_10.

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McIntosh, J. R., V. A. Lombillo, C. Nislow et E. A. Vaisberg. « Microtubule Dynamics and Chromosome Movement ». Dans The Cytoskeleton, 1–9. Berlin, Heidelberg : Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-79482-7_1.

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Straube, Anne. « How to Measure Microtubule Dynamics ? » Dans Methods in Molecular Biology, 1–14. Totowa, NJ : Humana Press, 2011. http://dx.doi.org/10.1007/978-1-61779-252-6_1.

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Purich, Daniel L., et James M. Angelastro. « Microtubule Dynamics : Bioenergetics and Control ». Dans Advances in Enzymology - and Related Areas of Molecular Biology, 121–54. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2006. http://dx.doi.org/10.1002/9780470123157.ch4.

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van Haren, Jeffrey, Lauren S. Adachi et Torsten Wittmann. « Optogenetic Control of Microtubule Dynamics ». Dans Methods in Molecular Biology, 211–34. New York, NY : Springer US, 2019. http://dx.doi.org/10.1007/978-1-0716-0219-5_14.

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Honore, Stéphane, et Diane Braguer. « Investigating Microtubule Dynamic Instability Using Microtubule-Targeting Agents ». Dans Methods in Molecular Biology, 245–60. Totowa, NJ : Humana Press, 2011. http://dx.doi.org/10.1007/978-1-61779-252-6_18.

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Bajer, Andrew S., Elena A. Smirnova et Jadwiga Molè-Bajer. « Microtubule Converging Centers — Implications for Microtubule Dynamics in Higher Plants ». Dans Chromosome Segregation and Aneuploidy, 225–39. Berlin, Heidelberg : Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-84938-1_19.

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Bajer, Andrew S., Elena A. Smirnova, Kolja A. Wawrowsky, Rainer Wolf et Jadwiga Molè-Bajer. « Microtubule Converging Centers : Implications for Microtubule Dynamics in Higher Plants ». Dans Biomechanics of Active Movement and Division of Cells, 471–78. Berlin, Heidelberg : Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-78975-5_20.

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Actes de conférences sur le sujet "Microtubules dynamics"

Aprodu, Iuliana, Alfonso Gautieri, Franco M. Montevecchi, Alberto Redaelli et Monica Soncini. « What Molecular Dynamics Simulations Can Tell Us About Mechanical Properties of Kinesin and Its Interaction With Tubulin ». Dans ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176316.

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Kinesin is a processive molecular motor found in various cells including neurons, that transports membrane-bound vesicles and organelles along the microtubule. Kinesin typically consists of three distinct domains: two large globular heads that attach to the microtubule, a central coiled region, and a light-chain that attaches to the cellular cargo. The metabolic energy that drives kinesins is provided in the form of ATP. The energy released by ATP hydrolysis is converted into direct movement after kinesin binds strongly to the microtubule. Two mechanisms were proposed to explain the movement of kinesin along microtubules: the “hand over hand” model in which the two heads alternate in the role of leading and the “inchworm” model in which one head always leads.

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Zdravković, Slobodan. « Kinks and breathers in nonlinear dynamics of microtubules ». Dans INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2014 (ICCMSE 2014). AIP Publishing LLC, 2014. http://dx.doi.org/10.1063/1.4897908.

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Enemark, So̸ren, Marco A. Deriu et Monica Soncini. « Mechanical Properties of Tubulin Molecules by Molecular Dynamics Simulations ». Dans ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95674.

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The basic unit in microtubules is αβ-tubulin, a hetero-dimer consisting of an α- and a β-tubulin monomer. The mechanical characteristics of the dimer as well as of the individual monomers may be used to obtain new insight into the microtubule tensile properties. In the present work we evaluate the elastic constants of each of the monomers and the interaction force between them by means of molecular dynamics simulations. Molecular models of α-, β-, and αβ-tubulin were developed starting from the 1TUB.pdb structure from the RSCB database. Simulations were carried out in a solvated environment using explicit water molecules. In order to measure the monomers’ elastic constants, simulations were performed by mimicking experiments carried out with atomic force microscopy. A different approach was used to determine the interaction force between the α- and β-monomers using 8 different monomer configurations based on different inter-monomer distances. The obtained results show an elastic constant value for α-tubulin of 3.4–3.9 N/m, while for the β-tubulin the elastic constant was measured to be 1.8–2.4 N/m. The maximum interaction force between the monomers was estimated to be 11.2 nN. In perspective, these outcomes will allow exchanging atomic level description with key mechanical features enabling microtubule characterisation by continuum mechanics approach.

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Hendricks, Adam G., Bogdan I. Epureanu et Edgar Meyho¨fer. « Collective Dynamics of Kinesin-1 Motor Proteins Transporting a Common Load ». Dans ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34702.

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Kinesin-1 is a motor protein essential to intracellular transport that converts the energy from ATP hydrolysis to directed movement along microtubules. Experimental and theoretical characterization of kinesin-1 has focused on single-molecule experiments. These experiments show that one motor is capable of transporting a cargo at speeds of about 1 μm/sec and maintaining contact with the microtubule for about 100 steps. In the cell, it is widely thought that several kinesin-1 motors cooperate to transport a cargo. Through a mechanistic model, we have extended the theoretical analysis of kinesin to describing transient and steady state behavior. A transient description is essential when studying collective behavior, as interaction between motors introduces time-varying loads. Herein, we interpret the kinesin motors as nonlinear, non-smooth oscillators and we employ metrics to characterize their cooperativity and to quantify their synchronization. These metrics are used to investigate the effect of the cargo linker stiffness, the load, and the difference in intrinsic velocity on the synchronization of two mechanically coupled motors.

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Salmon, E. D. « Video microscopy analysis of the polymerization dynamics of individual microtubules ». Dans The living cell in four dimensions. AIP, 1991. http://dx.doi.org/10.1063/1.40582.

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MATSSON, L. « DNA AND MICROTUBULES AS VORTEX-STRINGS IN SUPERCONDUCTOR-LIKE DYNAMICS ». Dans Proceedings of the First Workshop. WORLD SCIENTIFIC, 2001. http://dx.doi.org/10.1142/9789812811301_0018.

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Esteve, Marie-Anne, Stéphane Honore, Nathalie Mckay, Felix Bachmann, Heidi Lane et Diane Braguer. « Abstract 1977 : BAL27862 : A unique microtubule-targeted drug that suppresses microtubule dynamics, severs microtubules, and overcomes Bcl-2- and tubulin subtype-related drug resistance ». Dans Proceedings : AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010 ; Washington, DC. American Association for Cancer Research, 2010. http://dx.doi.org/10.1158/1538-7445.am10-1977.

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Pantaloni, D., M. F. Carlier, R. Melki, C. Combeau et C. Valentin-Ranc. « Role of nucleotide hydrolysis in the dynamics of actin filaments and microtubules ». Dans The living cell in four dimensions. AIP, 1991. http://dx.doi.org/10.1063/1.40581.

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Shi, Jianmin, Caixia Jia, Tao Han, Alfred C. H. Yu et Peng Qin. « Dynamics of Microtubules Disruption and Rearrangement in the Sonoporated Human Umbilical Vein Endothelial Cells ». Dans 2019 IEEE International Ultrasonics Symposium (IUS). IEEE, 2019. http://dx.doi.org/10.1109/ultsym.2019.8926089.

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Motie Shirazi, Mohsen, Omid Abouali, Homayoon Emdad, Mohammad Reza Nabavizade, Hossein Mirhadi et Goodarz Ahmadi. « Numerical Investigation of Irrigant Penetration Into Dentinal Microtubules ». Dans ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icnmm2014-21743.

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Root canal irrigation is an important procedure in endodontic treatment. After mechanical preparation of root canal, NaOCl, which is the most common antibacterial irrigant, is inserted by special needles. This work helps to remove bacteria and debris and dissolves the organic tissues in the root canal. In the vicinity of the main root canal, there are a large number of microchannels attached to its wall named “dentinal tubules”. The success of irragation depends on the penetration of irrigant in these tubules, which results in killing the bacteria and preventing complexities after root canal therapy. There is rather limited earlier research on modeling of dentinal tubules. Nevertheless, it has been shown that the flow rate, insertion depth and needle types affect the flow pattern in the root canal. The concentration difference between inserted irrigant and the liquid filling the tubules is the main driving force for penetration. Diffusion of irrigant, however, is a time dependent process and should be analyzed as an unsteady problem. In prior studies, the geometry was considered as cylinders with a constant diameter of 2.5μm and the effect of tapering was neglected. In reality the diameter varies from about 2.5μm near the pulp to about 1.5μm at the distance of 1 mm from the pulp. In the present study, a more detailed and exact model of dentinal tubules geometry was considered. The computational fluid dynamics (CFD) is used for the modeling of flow and diffusion of irrigant as a function of time. The unsteady and 3D continuity and Navier-Stokes equations as well as a scalar transport equation are solved and the flow field and the concentration of antibacterial irrigant were evaluated. The simulation results were compared to the earlier works. It was shown that the use of the correct detailed geometry of tubules led to noticeable differences compared to those found for the idealized model.

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Rapports d'organisations sur le sujet "Microtubules dynamics"

Orr, George A. Taxol Resistance and Microtubule Dynamics in Breast Cancer. Fort Belvoir, VA : Defense Technical Information Center, juin 2002. http://dx.doi.org/10.21236/ada407181.

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Orr, George A. Taxol Resistance and Microtubule Dynamics in Breast Cancer. Fort Belvoir, VA : Defense Technical Information Center, juin 2003. http://dx.doi.org/10.21236/ada416454.

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Orr, George A. Taxol Resistance and Microtubule Dynamics in Breast Cancer. Fort Belvoir, VA : Defense Technical Information Center, juin 2004. http://dx.doi.org/10.21236/ada425729.

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