WorldCat Identities

Massiera, Gladys (1976-....).

Works: 9 works in 11 publications in 2 languages and 11 library holdings
Roles: Opponent, Other, Author, Thesis advisor
Publication Timeline
Most widely held works by Gladys Massiera
Impact d'une perturbation mécanique ou photo-chimique sur le trafic intracellulaire by Kelly Aubertin( Book )

3 editions published between 2014 and 2017 in English and French and held by 3 WorldCat member libraries worldwide

The cell cytoplasm is crowded with membrane-delimited compartments, permanently communicating with each other. Such communication is permitted by active transport, also called intracellular trafficking, of vesicles along the cytoskeleton (actin filaments, microtubules), and mediated by molecular motors. In order to perturbate this intracellular trafficking, two different ways to apply controlled physical stresses have been performed. The first perturbation is a mechanical one: we used magnetic endosomes to probe and stress the cell body. To obtain them we internalized magnetic nanoparticles into mesenchymal stem cells (MSC) through the natural endocytosis pathway. These endosomes align into chains in the presence of a magnetic field. The mechanical perturbation then consists in applying a rotational magnetic field on these chains. When comparing the activity before and after a shear stress, we observed a decrease in the intracellular activity. The second perturbation has a photochemical origin, through the excitation of an internalized photosensitizer molecule (m-THPC or TPCS2a). By combining measurements of local cytoplasmic viscosity and intracellular activity, we found that photo-activation induced only a slight increase in viscosity while a massive slowing down of trafficking was observed. These effects are correlated with depolymerization of the microtubule network. The experiments demonstrate that these two photochemical agents have different intracellular impacts. Eventually, we studied a second effect of the photochemical perturbation which is the massive and rapid emission of extracellular vesicles
Propriétés physiques des globules rouges en agrégation by François Yaya( )

1 edition published in 2021 in English and held by 1 WorldCat member library worldwide

Red blood cells (RBC) are micron sized biological objects and the main corpuscular constituent of blood. It flows from larger arteries to very small capillaries. Utilizing a physical approach, this work aims to assess properties that govern blood flows and in particular the disaggregation and aggregation mechanisms of RBC at a single cell level. The interactions of RBCs are thus, investigated experimentally by measuring adhesive forces in the pN range in various model solutions thanks to optical tweezers. While two models for aggregation have been proposed: bridging and depletion, experimental evidence is still lacking to decide which mechanism prevails. The research presented here provides a new insight on the aggregation of RBCs and shows that the two models may not be exclusive. A complete 3-dimensional phase diagram of doublets has been established and confirmed by experiments by varying the adhesive forces and reduced cell volumes. Besides, the effect of aggregation was studied in vitro in a bifurcating microcapillary network and the distribution of aggregates and their stability in such a geometry are reported. Finally, experiments in flow allowed the characterization of the flow field around single RBCs at different velocities. Interesting vortical fluid structures have been also observed thanks to tracer nanoparticles
Development and characterization of new tools to investigate actin turnover by Jessica Colombo( )

1 edition published in 2020 in English and held by 1 WorldCat member library worldwide

La polymérisation de l'actine fournit la force nécessaire à de nombreux processus vitaux de la cellule eucaryote. La réaction de polymérisation est alimentée par des monomères chargés d'ATP, qui sont progressivement hydrolysés dans les filaments d'actine. Les segments des filaments riches en ADP sont progressivement désassemblés. La dynamique rapide du cytosquelette d'actine nécessite également un recyclage des monomères de l'état ADP à l'état ATP. La compréhension sur le recyclage sont pauvres. Nous manquons de sondes adaptées pour suivre l'état du nucléotide lié à l'actine et de systèmes biomimétiques appropriés pour étudier le renouvellement. Pour contourner ces limitations, j'ai procédé dans deux directions différentes mais complémentaires.(1) J'ai identifié des nucléotides fluorescents qui se lie à l'actine avec des caractéristiques similaires à celles de l'ATP: les dérivés de N6-(6-Amino)hexyl-ATP. Ces sondes permettent de suivre l'assemblage de l'actine et l'échange de nucléotides par microscopie et par anisotropie de fluorescence. Les interactions avec les protéines de liaison à l'actine restent fonctionnelles. Ces outils devraient permettre de déterminer les conditions dans lesquelles l'actine est recyclée.(2) J'ai conçu un système confiné: des émulsions d'eau dans l'huile avec des protéines purifiées. J'ai pu reconstituer la formation de cortex d'actine statiques, mais le système peut être implémenté avec des protéines de liaison à l'actine impliquées dans le recyclage.Les deux systèmes devraient être utilisés à l'avenir en synergie afin de déterminer les conditions biochimiques nécessaires pour maintenir un cytosquelette d'actine dynamique
Micelles géantes décorées de copolymères amphiphiles : propriétés structurales et dynamiques by Gladys Massiera( Book )

in French and held by 1 WorldCat member library worldwide

Etude du rôle des protéines partenaires de l'actine dans la mécanique des gels branchés de levure by Jessica Planade( )

1 edition published in 2016 in French and held by 1 WorldCat member library worldwide

In this experimental work we tried to quantify the mechanical properties of yeast branchedactin networks with regard to their biochemical composition. Actin is a semi-flexible biopolymerthat is assembled as part of the cytoskeleton. Proteins partners of actin (ABPs) shape itsfilaments into different type of networks. Arp2/3 is a protein complex that has the propertyto generate branched actin gels. Growing branched actin networks are of particular interest forboth biologists and physicists because of their ability to generate forces necessary to many vitalprocesses such as endocytosis. Here we study in vitro the mechanical properties of such networks,and we focus on the role of one type of actin binding proteins, the crosslinkers. This family ofproteins appears to play a role in both the elastic, viscous and plastic properties of the gels. Weare able to quantify and to compare the impact of three different crosslinkers on branched actinnetworks in yeast.In order to conduct said study, we combined two powerful experimental methods. We used asuperparamagnetic particle-based mechanical measurement technique that was developed in thelab and allows quantitative, high-throughput measurements on very thin gels. And the networkswere reconstituted in vitro by functionalization of the magnetic particles with Las17, which hasbeen showed to activate Arp2/3 for the yeast by our biologist collaborator. We furthermoreworked on both yeast extracts containing all the ABPs of the Arp2/3 networks, and with setsof a few purified proteins, in order to combine a « top-down » (use of mutations in yeast toprevent the expression of protein(s) of interest) and a « bottom-up » (addition of a protein ofinterest in a simplified system) approaches
Développement de vésicules hybrides polymère/lipide comme modèles de membrane cellulaire et micro-/nano-réacteurs by Martin Fauquignon( )

1 edition published in 2019 in French and held by 1 WorldCat member library worldwide

Hybrid vesicles, resulting from the combined self-assembly of amphiphilic copolymers and phospholipids, have been the subject of growing interest for several years. These assemblies can be seen as advanced vesicular structures compared to liposomes and polymersomes. They combine the chemical versatility and mechanical stability of the polymer membrane with the bio-functionality and permeability of the lipid membrane. These objects could be used in several fields: nano-reactor for enzymatic reactions, biomimetic model of cell membrane, etc. Previous work at the LCPO has led to the development of hybrid vesicles, mainly from triblock copolymers PEO-b-PDMS-b-PEO. However, these systems have shown limitations in terms of mechanical properties, since they have lower lysis strain than liposomes. The mixture of conformations (loop and extended) of triblock copolymers in the membrane would be at the origin of the poor mechanical stability of hybrid membranes. One approach to solve this problem is to control the conformation of polymer chains in the membrane. In this context, the objective of this thesis is to develop hybrid systems by substituting triblock copolymers with PDMS-b-PEO diblock copolymers. The latter are organized in bilayers in the membrane in the same way as phospholipids, which could stabilize the polymer/lipid interfaces.The work of this thesis consisted in synthesizing a series of diblock copolymers PDMS-b-PEO that can form polymersomes. The self-assembly parameters of the LUVs were determined (critical aggregation concentration, radius of gyration and hydrodynamics, number of aggregations, etc.). Membrane thickness measurements were performed by Cryo-TEM and neutron scattering. We were also interested in the membrane properties of polymersomes (fluidity and mechanical properties).Micrometric (GHUV) and nanometric (LHUV) hybrid vesicles were obtained from diblock copolymers and POPC, a model lipid. LHUV membrane formation and structuration was studied by Cryo-TEM, neutron scattering and fluorescence spectroscopy while GHUV membrane formation and structuration was checked by confocal microscopy. Different membrane structurations have been obtained for GHUVs, depending on the molar mass of thecopolymer or on the lipid composition. On the other hand, the LHUV's membranes appear to be homogeneous, regardless of the lipid fraction used.The permeability and mechanical properties of the hybrid membranes could be modulated according to the lipid composition. Surprisingly, polymersomes seem more permeable than liposomes. On the other hand, the use of diblock copolymers improve the mechanical properties of the hybrid membranes. The toughness values obtained are much higher than those measured for liposomes and for hybrid vesicles composed of triblock copolymers.Finally, the line tension associated with polymer/lipid interfaces was measured for the first time for hybrid systems. The line tension values founded are comparable to those measured for multi-phase lipid membranes
Crossing of a liquid-liquid interface by a droplet under centrifugal effect for a micro-encapsulation process by Hassan El Itawi( )

1 edition published in 2020 in French and held by 1 WorldCat member library worldwide

Migration cellulaire par forçage d'hétérogénéité by Mélina Durande( )

1 edition published in 2020 in French and held by 1 WorldCat member library worldwide

Cell migration is essential in various biological processes such as embryogenesis,wound healing, metastatic invasions or immune response. The objective of this thesiswas to identify and extract parameters useful for the establishment of physical modelsand the biological understanding of collective migration. To do this, we study cellmigration around an obstacle. Indeed, the presence of an obstacle in a flow induces heterogeneities which are discriminating for the establishment of models and we wantedto add to the information of velocities and deformations those of the forces exerted bythe cells on the substrate. Initally, the protein pattern geometry on which our cells are deposited is that of a band with an obstacle. Cells are confined by a block which, once removed, allows the tissue to invade free space and flow around the obstacle. The first part of this thesis studies this configuration, from a kinematic and proteinic levels point of view. In particular,we obtain master curves in velocity and deformation, a correlation between velocity and density, and an enrichment of the vimentin at the edge of the confined pattern andat the migration front. A set of relationships between actin, vimentin levels, density,deformation, and velocity is also found. Finally, it is shown that the direction of polarizationdefined by the core to center of mass vector of the cell is on average orthogonalto the direction of velocity. The strip geometry has the advantage of forcing the flow and being very controlled but has the disadvantage of requiring the installation of a block. It is not possible to lay the block on a substrate of low rigidity for force measurements, and to get around this problem we closed the boundary conditions and worked on a racetrack geometry that has two obstacles in the middle of each arm. We wagered on spontaneous generationof large-scale flow, which proved to be correct. The third part of the results studies theracetracks on a hard substrate (as opposed to a soft substrate for forces). The possibilityof generating a long-range flow and the presence of vimentin at the edge of the pattern are retained. We also note that the velocity- density relationship is no longer valid in this geometry, which attests that when it exists, it is in fact a consequence of the spreading dynamics of the monolayer and not of the migration dynamics as such. There is also a relationship between actin and vimentin which illustrates three possible cell states. The first corresponds to very deformed and vimentin-rich cells, the second to very dense and actin-rich cells, and the third to intermediate states of deformation and density where the cells move and where actin and vimentin vary together. The last part of this thesis consists in studying the forces (soft substrate) by traction force microscopy. These experiments confirm that a migrating monolayer is contractile and we show that it is equivalent to measure the displacement of beads in the substrate or the displacement of cells at small scale on phase images. In other words, the instantaneous velocity (the one used by the theoreticians but not experimentally measurable) is equal to the bead position derivative.We conclude that there is continuity of motion between the substrate and the cell. Keeping in mind our first goal to study the migration around an obstacle, the development of a large-scale system oracetracksallows us to better understand the underlying ingredients of migration while developingthe experimental framework that allows quantitative comparisons between systems
Procédé d'encapsulation à base d'hydrogels pour le développement de micro-tissus cellulaires by Wafa Bouhlel( )

1 edition published in 2018 in French and held by 1 WorldCat member library worldwide

This thesis concerns the improvement of a hydrogel encapsulation process for three-dimensional cell culture. Submillimetric capsules are formed via high speed co-extrusion of macromolecules solutions, thereby forming a compound jet. The drops resulting from the fragmentation of the jet have a core/ shell type geometry where shell is composed of alginate. This layer is then solidified after immersion in a gelling bath. The use of biological materials required the implementation of a sequential injection system to manipulate small volumes, less than 1 mL. This approach is then accompanied by a longitudinal variation of the concentration of the suspended particles flowing in the injection tube. This dispersion can be inhibited by adding air bubbles at each end of the sample to segment it. A destabilization of the suspension initially homogeneous is observed when liquid inertia comes into play at the particle's scale. These micrometric particles induce a flapping motion and jet speed fluctuations causing the coalescence of the drops and thus a size polydispersity. Finally, a collagen hydrogel, which mimics an extracellular matrix, has been implemented in the capsule's core to promote adhesion of epithelial cells forming intestine and bile ducts. Within this matrix, the cells form a polarized and functional epithelium. The formation of these collagen capsules required the formulaiton of the collagen solution compatible with the process and the physiological conditions of the cells
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Audience level: 0.96 (from 0.93 for Micelles g ... to 1.00 for Impact d'u ...)