Papers by Tzvetelina Chevolleau
Genetic approches to modify the accumulation of antenna proteins (LHC and ELIP) from the nucleus encoded genome
AIX-MARSEILLE2-BU Sci.Luminy (130552106) / SudocSudocFranceF
Expert Opinion on Drug Delivery, 2020
Glezer (2020) User experience for manual injection of 2 mL viscous solutions is enhanced by a new... more Glezer (2020) User experience for manual injection of 2 mL viscous solutions is enhanced by a new prefillable syringe with a staked 8 mm ultra-thin wall needle,
Mathematical Modelling of Fibroblast shape Transition on Arrays of Adhesive Micropatterns with Varying Pitch
Cell adhesion to the extracellular matrix is crucial to many physiological events since it underl... more Cell adhesion to the extracellular matrix is crucial to many physiological events since it underlies cell motility and cell proliferation. Cell shape and cell migration depend on the forces developed within the cytoskeleton. These forces are highly regulated at the adhesion site through feedback mechanisms. The observation of cells plated on culture dishes shows continuous membrane oscillations with recurring patterns. In that experimental case, the cell cytoskeleton dynamics never reaches a steady state since adhesion is homogeneous and never strong enough for forces to develop and to stabilize the cell shape. Engineered micrometric adhesive patches have therefore been used to discretize and limit the surface for cell adhesion. With these new adhesive conditions, the cell becomes able to develop stronger adhesions through a mechanism of integrin clustering and to develop competing stress fibers ultimately converging to stable geometrical cell shapes. Arrays of adhesive micropatches...
The light stress-induced protein ELIP2 is a regulator of chlorophyll synthesis in Arabidopsis thaliana
The Plant Journal, 2007
The early light-induced proteins (ELIPs) belong to the multigenic family of pigment-binding light... more The early light-induced proteins (ELIPs) belong to the multigenic family of pigment-binding light-harvesting complexes. ELIPs accumulate transiently and are believed to play a protective role in plants exposed to high levels of light. Constitutive expression of the ELIP2 gene in Arabidopsis resulted in a marked reduction of the pigment content of the chloroplasts, both in mature leaves and during greening of etiolated seedlings. The chlorophyll loss was associated with a decrease in the number of photosystems in the thylakoid membranes, but the photosystems present were fully assembled and functional. A detailed analysis of the chlorophyll-synthesizing pathway indicated that ELIP2 accumulation downregulated the level and activity of two important regulatory steps: 5-aminolevulinate synthesis and Mg-protoporphyrin IX (Mg-Proto IX) chelatase activity. The contents of glutamyl tRNA reductase and Mg chelatase subunits CHLH and CHLI were lowered in response to ELIP2 accumulation. In contrast, ferrochelatase activity was not affected and the inhibition of Heme synthesis was null or very moderate. As a result of reduced metabolic flow from 5-aminolevulinic acid, the steady state levels of various chlorophyll precursors (from protoporphyrin IX to protochlorophyllide) were strongly reduced in the ELIP2 overexpressors. Taken together, our results indicate that the physiological function of ELIPs could be related to the regulation of chlorophyll concentration in thylakoids. This seems to occur through an inhibition of the entire chlorophyll biosynthesis pathway from the initial precursor of tetrapyrroles, 5-aminolevulinic acid. We suggest that ELIPs work as chlorophyll sensors that modulate chlorophyll synthesis to prevent accumulation of free chlorophyll, and hence prevent photooxidative stress.
Journal of Pharmaceutical Sciences, 2014
Prefilled syringes (PFSs) offer improvements in the delivery of drugs to patients compared with t... more Prefilled syringes (PFSs) offer improvements in the delivery of drugs to patients compared with traditional vial presentations and are becoming necessities in an increasingly competitive biologics market. However, the development of a product in a PFS must take into account potential incompatibilities between the drug and the components of the syringe. One such component is silicone oil, which has previously been suggested to promote protein aggregation, loss of soluble protein, and an increase in the particulate content of injectable formulations. This study evaluated the particulate content in a model buffer system (polysorbate 80/phosphate-buffered saline) after agitation in glass syringes with a novel cross-linked silicone coating. We also evaluated the compatibility of two monoclonal antibodies with these syringes. We report that syringes with this novel coating, compared with standard siliconized syringes, exhibited reduced particle content and enhanced integrity of the lubricant layer as determined by reflectometry, optical microscopy, and time-of-flight secondary ion mass spectrometry measurements, while maintaining the desired functional properties of the syringe and the antibodies' stability profiles as determined by high-performance size-exclusion chromatography. Enhanced integrity of the lubricant coating led to significantly fewer subvisible particles in the liquid formulations, particularly after agitation stresses introduced by shipping of the syringes.
Microelectronic Engineering, 2008
Approches génétiques pour modifier le contenu en protéines antennes (LHC et ELIP) codées par le génome nucléaire
Http Www Theses Fr, 2005
The motility of normal and cancer cells in response to the combined influence of the
Control of cell morphodynamic and displacement orientation by precise tuning between substrate nanopatterning and rigidity
Biomaterials, 2008
Cell adhesion and migration are strongly influenced by extracellular matrix (ECM) architecture an... more Cell adhesion and migration are strongly influenced by extracellular matrix (ECM) architecture and rigidity, but little is known about the concomitant influence of such environmental signals to cell responses, especially when considering cells of similar origin and morphology, but exhibiting a normal or cancerous phenotype. Using micropatterned polydimethylsiloxane substrates (PDMS) with tuneable stiffness (500kPa, 750kPa, 2000kPa) and topography (lines, pillars or unpatterned), we systematically analyse the differential response of normal (3T3) and cancer (SaI/N) fibroblastic cells. Our results demonstrate that both cells exhibit differential morphology and motility responses to changes in substrate rigidiy and microtopography. 3T3 polarization and spreading are influenced by substrate microtopography and rigidity. The cells exhibit a persistent type of migration, which depends on the substrate anisotropy. In contrast, the dynamic of SaI/N spreading is strongly modified by the substrate topography but not by substrate rigidity. SaI/N morphology and migration seem to escape from extracellular cues: the cells exhibit uncorrelated migration trajectories and a large dispersion of their migration speed, which increases with substrate rigidity.
Microelectronic …, 2009
In order to get a better understanding of amoeba-substrate interactions in the processes of cellu... more In order to get a better understanding of amoeba-substrate interactions in the processes of cellular adhesion and directional movement, we engineered glass surfaces with defined local adhesion characteristics at a micrometric scale. Amoeba (Dictyostelium dicoideum) are capable to adhere to various surfaces independently on the presence of extracellular matrix proteins. This paper describes the strategy used to create selective adhesion patterns using an appropriate surface chemistry and shows the first results of locally confined amoeba adhesion. The approach is based on the natural ability of Dictyostelium to adhere to various types of surfaces (hydrophilic and hydrophobic) and on its inability to spread on inert surfaces, such as the block copolymer of polyethylene glycol and polypropylene oxide, named Pluronic. We screened diverse alkylsilanes, such as methoxy, chloro and fluoro silanes for their capacity to anchor Pluronic F127 efficiently on a glass surface. Our results demonstrate that hexylmethyldichlorosilane (HMDCS) was the most appropriate silane for the deposition of Pluronic F127. A complex dependence between the physico-chemistry of the silanes and the polyethylene glycol block copolymer attachment was observed. Using this method, we succeed in scaling down the micro-fabrication of pluronic-based adhesion patterns to the amoeba cell size (10µm). This original pluronic patterning method should prove useful as a tool for controlling cell adhesion and directional movement in amoeba.
Mathematical Modelling of Natural Phenomena, 2010
In this paper, we propose a computational model to investigate the coupling between cell's adhesi... more In this paper, we propose a computational model to investigate the coupling between cell's adhesions and actin fibres and how this coupling affects cell shape and stability. To accomplish that, we take into account the successive stages of adhesion maturation from adhesion precursors to focal complexes and ultimately to focal adhesions, as well as the actin fibres evolution from growing filaments, to bundles and finally contractile stress fibres. We use substrates with discrete patterns of adhesive patches, whose inter-patches distance can be modulated in order to control the location of the adhesions and the resulting fibres architecture. We then investigate the emergence of stable cell morphologies as a function of the inter-patches distance, for two different cell phenotypes generated from the model. Force generated by the stress fibres on the focal adhesions and specifically the influence of the cell contractility are also investigated. Our results suggest that adhesion lifetime and fibre growing rate are the key parameters in the emergence of stable cell morphologies and the limiting factors for the magnitude of the mean tension force from the fibres on the focal adhesions.
Mathematical Modelling of Natural Phenomena, 2010
In this paper, we propose a computational model to investigate the coupling between cell's adhesi... more In this paper, we propose a computational model to investigate the coupling between cell's adhesions and actin fibres and how this coupling affects cell shape and stability. To accomplish that, we take into account the successive stages of adhesion maturation from adhesion precursors to focal complexes and ultimately to focal adhesions, as well as the actin fibres evolution from growing filaments, to bundles and finally contractile stress fibres. We use substrates with discrete patterns of adhesive patches, whose inter-patches distance can be modulated in order to control the location of the adhesions and the resulting fibres architecture. We then investigate the emergence of stable cell morphologies as a function of the inter-patches distance, for two different cell phenotypes generated from the model. Force generated by the stress fibres on the focal adhesions and specifically the influence of the cell contractility are also investigated. Our results suggest that adhesion lifetime and fibre growing rate are the key parameters in the emergence of stable cell morphologies and the limiting factors for the magnitude of the mean tension force from the fibres on the focal adhesions.
The Plant Cell Online, May 1, 2007
The chloroplast signal recognition particle (cpSRP) and its receptor (cpFtsY) target proteins bot... more The chloroplast signal recognition particle (cpSRP) and its receptor (cpFtsY) target proteins both cotranslationally and posttranslationally to the thylakoids. This dual function enables cpSRP to utilize its posttranslational activities for targeting a family of nucleus-encoded light-harvesting chlorophyll binding proteins (LHCPs), the most abundant membrane proteins in plants. Previous in vitro experiments indicated an absolute requirement for all cpSRP pathway soluble components. In agreement, a cpFtsY mutant in Arabidopsis thaliana exhibits a severe chlorotic phenotype resulting from a massive loss of LHCPs. Surprisingly, a double mutant, cpftsy cpsrp54, recovers to a great extent from the chlorotic cpftsy phenotype. This establishes that in plants, a new alternative pathway exists that can bypass cpSRP posttranslational targeting activities. Using a mutant form of cpSRP43 that is unable to assemble with cpSRP54, we complemented the cpSRP43-deficient mutant and found that this subunit is required for the alternative pathway. Along with the ability of cpSRP43 alone to bind the ALBINO3 translocase required for LHCP integration, our results indicate that cpSRP43 has developed features to function independently of cpSRP54/cpFtsY in targeting LHCPs to the thylakoid membranes.
Uploads
Papers by Tzvetelina Chevolleau