1,064 research outputs found
Diffusion of nanoparticles in the cell cytoplasm
No full textIn Etoc 2018, we presented the diffusive behavior inside the cytosol of living cells for different kind of nanometric sized nanoparticles. We showed that the passivation of the particles is the main parameter that regulate the diffusion properties of particles smaller than 70nm not only in Hela cells but also in RPE1 and MSC cells.
Here we open the data for the MSC cells.
Experiments consists in the recording of small subregions of the cytoplasm located at the periphery of the cell.
A README file is included in the archive with the recording parameters.
DATA were recorded by Elie BALLOUL
Scripts were written by Mathieu COPPEY, Fred ETOC and modified by Elie BALLOUL.(to use polyfit instead of ezyfit)
We also make available the scripts that we used to generate the maps.
Some functions were found in Matlab Central and their corresponding license is in their respective folders.</p
Analysis of Mathieu Equation Stable Solutions in the First Zone of Stability
No full textAbstractThe paper presents the results of a homogeneous Mathieu equation studies. Mathieu equation solutions are oscillations, modulated in amplitude and frequency. In the computational experiments we found dependences of the given oscillations on the ratio of the coefficients. These dependences are shown in graphs that can be used for an approximate estimation of the Mathieu equation solutions without integration
Pensar las escalas para pensar las luchas: Autor: Mathieu UHEL
No full textA través de un título sugerente, “pensar las escalas para pensar las luchas”, Mathieu Uhel entreteje la construcción teórico-crítica del concepto escala, generada por la geografía radical anglosajona de finales del siglo XX, con la necesidad/utilidad práctica de la escala para concienciar las luchas sociales. El artículo cumple un doble propósito: por un lado, delinear los elementos de lectura sobre el concepto escala; y, con ello, promover la atención de esta problemática en las luchas contemporáneas. En un primer apartado, Uhel ubica las discusiones académicas en torno a la escala, como herramienta metodológica útil para comprender la complejidad de las sociedades capitalistas; en el segundo apartado, el autor avanza la exposición en torno al contexto de la dimensión escalar del imperialismo capitalista; finalmente, el autor se centra en el rol de la actividad política a escala nacional en la tensa relación entre las imposiciones del capital y la lucha social.Por meio de um título sugestivo, “pensando escalas para pensar lutas”, Mathieu Uhel entrelaça a construção teórico-crítica do conceito de escala, gerado pela geografia radical anglo-saxônica do final do século XX, com a necessidade / utilidade prática escala para aumentar a consciência das lutas sociais. O artigo tem um duplo propósito: por um lado, delinear os elementos de leitura sobre o conceito de escala; e, com isso, promover atenção a esse problema nas lutas contemporâneas. Na primeira seção, Uhel localiza as discussões acadêmicas em torno da escala, como uma ferramenta metodológica útil para compreender a complexidade das sociedades capitalistas; na segunda seção, o autor avança a exposição em torno do contexto da dimensão escalar do imperialismo capitalista; por fim, o autor enfoca o papel da atividade política em escala nacional na tensa relação entre as imposições do capital e a luta social.Mathieu Uhel\u27s suggestive title, “Thinking about scales to think about struggles”, he interweaves the theoretical-critical construction of concept scale, generated by radical Anglo-Saxon geography in the late 20th century, with it´s practical utility to social struggles. The article serves two purposes: on the one hand, Uhel locates academic discussion around scale; and, with this, he promotes attention to this problem in contemporary struggles. In the first section, Uhel locates academic discussions around scale, as a useful methodological tool to understand the complexity of capitalist societies; in the second section, the author advances the argument around the context of the scalar dimension of capitalist imperialism; finally, the author focuses on the role of political activity on a national scale in the tense relationship between the impositions of capital and the social movement
Imaging the dynamic architecture of chromatin at the single cell level
No full textLa structure de la chromatine joue un rôle crucial dans la régulation de plusieurs fonctions cellulaires chez les cellules de mammifères. Perturber l’organisation spatiale de la chromatine peut avoir des conséquences dramatiques sur la vie d’une cellule et peut amener`des pathologies graves chez les organismes. Deux facteurs nucléaires, CTCF et Cohesine, sont parmi les principaux acteurs dans la régulation et le maintien de l’architecture de l’ADN. Des avancements importants ont révélé ́la complexité ́des mécanismes qui régulent l’organisation de la chromatine, mais le domaine manque encore d’une description dynamique à l’échelle de la cellule et de la molécule unique. Cette étude est centrée sur la description de la dynamique de CTCF et Cohesin réalisé ́avec de méthodes de suivi de la molécule unique dans des cellules souche embryonnaires vivantes de souris. L’interaction entre ces deux facteurs a été étudiée à travers la caractérisation de la dynamique de Cohesin en absence de CTCF et dans le contexte d’autres altérations biologiques.Chromatin structure and cellular function are tightly linked in the nucleus of mammalian cells. Disruption of chromatin spatial organisation dramatically affects the life of a cell and eventually leads to severe pathologies in entire organisms. Two nuclear factors, CTCF and Cohesin, have been found to play a crucial role in the regulation and maintenance of DNA architecture. Huge advancements have been made in the understanding of the mechanisms behind chromatin arrangement but the field is still lacking a dynamic picture at the single cell and single molecule level. This study provide this study provides insight into the dynamics of CTCF and Cohesin through single particle tracking of CTCF and Cohesin dynamics achieved with single molecule tracking in living mouse embryonic stem cells. The interplay between these two factors was studied by looking at Cohesin’s behaviour in the absence of CTCF and in the context of other biological alterations
Mathieu Ichou, Les Enfants d’immigrés à l’école
No full textIt is common to hear in the fields of educational and immigration sociology that on average, the children of immigrants do not perform as well in school as children of native-born parents. Mathieu Ichou offers an innovative sociological analysis on a topic that is heavily exploited by political and media discourse, and subject to much scientific controversy. The author takes distance from the homogenized vision of a “second generation” of students who have totally failed academically, and rep..
L'impatto dell'attività tintoria sull'ambiente. Firenze alla fine del Medioevo
No full textThe author aims to examine and categorize the range of dyeings materials used in the Florentine wool and silk textile industries in the late Middle Ages, focusing mainly on those produced within the regional space in order to evaluate the impact of the Florentine dyeing activity on the natural environment and the productive landscape of the Tuscan countryside. In particular, the author establishes a line of demarcation between cultivated and uncultivated resources in order to verify which constitutes an indication of the level of industrial development of medieval textile production. This further focuses on how the transition from the exploitation of wild resources to the exploitation of cultivated resources could reflect a greater degree of economic integration between the countryside and the city and contribute to the formation of a regional economic space
Cell to cell communication by diffusible molecules
No full textNon UBCUnreviewedAuthor affiliation: Curie Institute ParisResearche
Contrôle optogénétique de la polarité de la migration cellulaire par la voie de signalisation RhoA
No full textLes cellules perçoivent des signaux chimiques ou physiques externes, les interprètent à l'aide de leur réseau de protéines et modifient leur comportement en conséquence. Mieux comprendre les systèmes vivants passe par le décryptage des signaux biochimiques à l'intérieur de la cellule, qui sont responsables de réponses phénotypiques spécifiques. Parmi tous les processus cellulaires, la migration cellulaire est fascinante car elle révèle la capacité des cellules à agir comme des unités individuelles ou collectives, qui se polarisent par elles-mêmes et ont leur propre indépendance.Les Rho-GTPases jouent un rôle clé dans la migration des cellules de mammifères: ce sont des protéines souvent considérées comme des contrôleurs du cytosquelette cellulaire, et donc responsables des changements morphologiques provoqués par les filaments et les moteurs tels que l'actine et la myosine. Pour sonder le réseau de protéines et étudier les liens de cause à effet sur le comportement cellulaire ou multicellulaire, l'optogénétique est un outil formidable qui permet un contrôle spatio-temporel précis de l'activité des Rho-GTPases.Ce manuscrit aborde la question du contrôle de la migration cellulaire et multicellulaire par les Rho-GTPases à travers deux systèmes modèles différents, grâce à l'optogénétique.Le premier projet porte sur la migration et la polarisation de cellules individuelles après le recrutement membranaire d'un activateur de la protéine RhoA (un domaine GEF). En utilisant l'optogénétique, j'ai découvert qu'un domaine GEF est capable de déclencher deux réponses phénotypiques opposées dans la même lignée cellulaire : une protrusion ou une rétraction. La caractérisation des phénotypes a permis de montrer que le choix est dicté par la concentration de l'activateur optogénétique présent dans la cellule avant l'activation. J'ai décrit la conséquence de ce changement de concentration sur les voies de signalisation impliquées et j'ai développé un modèle qui récapitule les principaux résultats avec peu de paramètres. Grâce à lui, j'ai pu contrôler les deux effets opposés de cette protéine dans la même cellule. Ce projet révèle et explique un exemple clair de multiplexage des signaux cellulaires, à savoir la capacité d'une voie de signalisation à avoir plusieurs fonctions, ici dans le même contexte cellulaire et à l’échelle de la minute.Le second projet a été réalisé en collaboration avec l'équipe de Fanny Jaulin de l'Institut Gustave Roussy. Il visait à comprendre un nouveau mode de migration collective découvert par eux dans l'initiation des métastases du cancer colorectal. Cette migration d'amas épithéliaux de dizaines à centaines de cellules repose sur des propriétés uniques : absence d'adhésions focales sur le substrat, environnement confiné, et forte contractilité. Ce mode de migration collective rappelle la migration amiboïde d'une seule cellule. En utilisant des outils optogénétiques développés dans notre laboratoire et des canaux microfluidiques, j'ai conçu et réalisé des expériences pour comprendre le rôle des Rho-GTPases dans la polarité et la migration de ces sphères multicellulaires. Mon principal résultat est qu'un déséquilibre de contractilité déclenché par la protéine RhoA est suffisant pour contrôler la polarité et le mouvement du groupe de cellules.Dans l'ensemble, mon doctorat a permis de comprendre comment la voie de signalisation RhoA agit pour établir une polarité dans la migration cellulaire : je l'ai examinée au niveau de la cellule unique, révélant un exemple unique de multifonctionnalité d'une protéine, ainsi qu'au niveau collectif, disséquant un nouveau mode de migration collective des cellules cancéreuses.Cells sense external chemical or physical signals, interpret them using their protein network and modify their behavior accordingly. A better understanding of living systems involves deciphering how biochemical signals are transmitted within the cell, leading to specific phenotypic responses. Among all cellular processes, cell migration is fascinating because it reveals the ability of cells to act as individual or collective units, which polarize by themselves and have their own independence.Rho-GTPases play a key role in mammalian cell migration: they are proteins often regarded as controllers of the cellular cytoskeleton, and therefore responsible for morphological changes caused by filaments and motors such as actin and myosin. To probe the protein network and study causal links on cellular or multicellular behavior, optogenetics is a great tool that enables precise spatio-temporal control of Rho-GTPase activity.This PhD manuscript addresses the question of the control of single and multicellular migration by Rho-GTPases, using optogenetics in two different model systems.The first project focuses on the migration and polarization of single cells following membrane recruitment of a RhoA activator (a GEF domain). Using optogenetics, I discovered that a GEF domain is capable of triggering two opposite phenotypic responses in the same cell line: protrusion or retraction. Characterization of the phenotypes showed that the choice is dictated by the concentration of optogenetic activator present in the cell prior to activation. I described the consequences of this change in concentration on the signalling pathways involved, and developed a model that summarizes the main results with few parameters. Thanks to it, I was able to control the two opposite effects of this protein in the same cell. This project reveals and explains a clear example of cellular signal multiplexing, i.e. the ability of a signaling pathway to have multiple functions, here in the same cellular context and on a minute scale.The second project was carried out in collaboration with Fanny Jaulin's team at the Institut Gustave Roussy. It aimed to understand a new mode of collective migration discovered by them in the initiation of colorectal cancer metastases. This migration of epithelial clusters of tens to hundreds of cells relies on unique properties: absence of focal adhesions to the substrate, confined environment, and high contractility. This mode of collective migration is reminiscent of single cell amoeboid migration. Using optogenetic tools developed in our laboratory and microfluidic channels, I designed and carried out experiments to understand the role of Rho-GTPases in the polarity and migration of these multicellular spheres. My main finding is that a contractility imbalance triggered by the RhoA protein is sufficient to control the polarity and movement of the cell group.Overall, my PhD has provided insight into how the RhoA signaling pathway acts to establish polarity in cell migration: I examined it at the single-cell level, revealing a unique example of multifunctionality of a protein, as well as at the collective level, dissecting a novel mode of collective cancer cell migration
Mathieu de Fossey: su visión del mundo indígena mexicano
No full textThroughout these pages the author shows how Mathieu de Fossey perceived that it was not easy to make indigenous communities fit within the mould of the nation-state which, being based on the liberal and egualitarian ideology, was against the recognition of special regimes, such as those that created a peculiar status for the native population of the American territory during the period of Spanish colonial domination
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