Дисертації з теми "Singole cellule"
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Antoniolli, Francesca. "PROGETTAZIONE E CARATTERIZZAZIONE DI UN BIOSENSORE MEMS." Doctoral thesis, Università degli studi di Trieste, 2008. http://hdl.handle.net/10077/2755.
Повний текст джерелаNegli ultimi anni, le cellule sono state oggetto di studio approfondito e, in taluni casi, di esperimenti molto sofisticati. Tuttavia, benché si conosca molto circa la loro struttura, poche sono le informazioni sulla meccanica cellulare e sulla risposta cellulare agli stimoli meccanici. Le cellule, infatti, possono sentire forze meccaniche e convertirle in risposte biologiche, oppure, viceversa, è da tempo noto come segnali biologici e biochimici influenzino l’abilità cellulare nel sentire, generare e sopportare forze di tipo meccanico. Negli ultimi anni sono stati ideati e realizzati svariati meccanismi per l’applicazione di forze meccaniche su cellule e la rilevazione delle conseguenti deformazioni. Questi sistemi, però, presentano dei limiti: - la forza esercitata non è adeguata al fenomeno investigato; - lo studio viene effettuato su un’intera popolazione di cellule; - la forza è esercitata localmente e non sull’intera cellula. Il presente lavoro di tesi, avente come obiettivo primo lo sviluppo, la progettazione e la realizzazione di un dispositivo per la sollecitazione meccanica della singola cellula e la rilevazione delle conseguenti deformazioni, si è focalizzato sullo studio di dispositivi che potessero bypassare i suddetti limiti. La scelta è ricaduta nei Sistemi Micro Elettro Meccanici, dal momento che, oltre ad avere dimensioni compatibili con le caratteristiche cellulari ed assicurare modesti costi realizzativi ed operativi, garantiscono - la possibilità di applicare forze in un ampio range (pN-µN); - la possibilità di effettuare studi sulla singola cellula, ed in particolare su cellule aderenti; - la possibilità di stimolare l’intera cellula, e non soltanto una porzione locale di questa. La prima parte del lavoro è stata rivolta alla messa a punto di dispositivi che, concepiti in maniera analoga a quelle che sono le tradizionali macchine universali per test meccanici, potessero consentire l’ancoraggio della singola cellula su di una piattaforma di geometrie differenti a seconda che si volesse applicare una sollecitazione di trazione uniassiale, biassiale, pluriassiale oppure di taglio. Tali dispositivi tuttavia hanno riscontrato diverse problematiche quando operanti in soluzioni saline quali i medium cellulari. Sono stai quindi concepiti e sviluppati dei nuovi dispositivi che potessero bypassare le problematiche riscontrate con i primi: il MEMS è stato quindi sdoppiato su due outline di 2x2 mm, di cui una ospitante il motore per l’attuazione del dispositivo operante in aria l’altra ospitante la piattaforma per la collocazione della cellula in esame. Per completare il funzionamento di tali dispositivi è stata sviluppata e realizzata con successo una tecnica di collegamento di questi mediante una fibra di carbonio ancorata ai MEMS mediante wire bonding. Infine sono state acquisite e messe a punto la strumentazione e le tecniche che potessero consentire di operare con cellule viventi: è stato individuato un materiale tale da consentire un ancoraggio ottimale della cellula e con il quale si potesse funzionalizzate localmente la piattaforma per la cellula; è stato allestito un laboratorio per colture cellulari presso il Dipartimento dei Materiali e delle Risorse Naturali; è stata messa a punto una tecnica per la manipolazione di singole cellule; sono state infine eseguite alcune preliminari prove di trazione sulla singola cellula.
XX Ciclo
1979
Moussy, Alice. "Caractérisation des premières étapes de différenciation des cellules hématopoïétiques à l'échelle de la cellule unique." Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEP029/document.
Повний текст джерелаDespite intensively studies, the fundamental mechanisms of cell fate decision during cellular differentiation still remain unclear. The deterministic mechanisms, often based on studies of large cell populations, cannot explain the difference between individual cell fates choices placed in the same environment. The aim of my thesis work is to study the first steps of hematopoietic cell differentiation at the single cell level thanks to transcriptomic, proteomic and morphological analyses. Two differentiation models have been used: T regulatory lymphocytes and human cord blood-derived CD34+ cells. The behavior of individual cells following stimulation has been analyzed. Using time-lapse microscopy coupled to single cell molecular analyses, we could demonstrate that the cell fate choice is not a unique, programmed event. First, the cell reaches a metastable “multi-primed” state, which is characterized by a mixed lineage gene expression pattern. After transition through an “uncertain”, unstable state, characterized by fluctuations between two phenotypes, the cell reaches a stable state. Our observations are coherent with a stochastic model of cell fate decision. The differentiation is likely to be a spontaneous, dynamic, fluctuating and not a deterministic process. The cell fate decisions are taken by individual cells
MALLIA, SELENE. "La genomica su singola cellula rivela la gerarchia e l'architettura clonale nelle Neoplasie Mieloproliferative." Doctoral thesis, Università degli studi di Modena e Reggio Emilia, 2022. http://hdl.handle.net/11380/1278821.
Повний текст джерелаSomatic mutations in Hematopoietic Stem Cells (HSCs) cause Myeloproliferative Neoplasms (MPNs), including Polycythemia Vera, Essential Thrombocythemia and Primary Myelofibrosis (PMF). PMF is a heterogeneous disorder consisting of bone marrow fibrosis, megakaryocyte hyperplasia and extramedullary hematopoiesis and is characterized by the worst prognosis among MPNs. About 15-20% of patients are unresponsive to conventional therapies and develop Acute Myeloid Leukemia (AML). In HSCs the main mutations, identified as “driver mutations” during MPNs pathogenesis, involve JAK2, CALR and MPL genes; in addition, many other genetic alterations contribute to the prognosis worsening and the development of AML. Disease progression and leukemic evolution in PMF results from an increase of the genomic complexity and clonal heterogeneity. Many studies confirmed that the mutational acquisition order affects the clinical outcome. However, the clonal architecture determining disease evolution and the clones guiding leukemic transformation are poorly understood. Recent studies demonstrate that single-cell (sc) genomics is a sensitive technique suitable to study clonal heterogeneity and to detect the evolution of the malignant cells in hematological neoplasms. For this reason, we used the sc-genomics approach to clarify the clonal complexity in PMF. Firstly, we developed a workflow for CD34+ Hematopoietic Stem Progenitor Cells (HSPCs) isolation from cord blood, fixation and immunostaining for CD34, in order to singularly separate the cells by DEP-array system (Menarini Silicon Biosystem) and to obtain a cell population suitable for sc-analysis. Then, we compared different whole genome amplification (WGA) protocols for single cells in order to obtain a uniform DNA amplification for Sanger sequencing and minimize allele drop out effect. Based on this method, we analyzed the CD34+ HSPCs of a PMF patient carrying JAK2V617F and other MPN frequent mutations. This patient was treated with JAK2-inhibitor Ruxolitinib but he was unresponsive to therapy and evolved to AML. In order to reconstruct the clonal hierarchy and architecture, we analyzed CD34+ cells during chronic phase (T1), the accelerated phase (T2) and the AML phase (T3). By means to sc-analysis, we established that TET2 was the first mutated gene, preceding JAK2 mutation, and this probably conferred a lower sensitivity to treatment. Moreover, we identified an increase of the allele burden of the TP53 mutation during disease progression, suggesting that TP53-mutated clones supported the accelerated (T2) phase. Interestingly, we already detected in T1 phase a small cell fraction, undetectable by bulk NGS and carrying the leukemogenic FLT3 mutation, probably driving the T3 phase. Finally, we characterized SRSF2 homozygous mutation that has not been described yet. Altogether our data demonstrate that sc-genomics is a promising method to uncover clonal heterogeneity in MPNs, highlighting the early occurrence of pro-leukemic mutations and to describe the real scenario of mutational events in hematological diseases.
Caccianini, Laura. "Imagerie de l'architecture dynamique de la chromatine dans la cellule unique." Thesis, Paris Sciences et Lettres (ComUE), 2019. https://tel.archives-ouvertes.fr/tel-02896692.
Повний текст джерелаChromatin 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
Holt, Brian D. "Cellular Processing of Single Wall Carbon Nanotubes." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/397.
Повний текст джерелаGeisler, Hubert. "Structuration d'hydrogels thermoactivables pour l'analyse de cellules uniques." Electronic Thesis or Diss., Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLS001.
Повний текст джерелаWe present in this work a new microfluidic technology aiming at isolating single cells by the use of thermoactuable polymers. One of the polymers we use is polyNIPAM, a polymer that can expand its volume by 400% in water when the temperature is set under 32°C and can shrink down when it is set over 34°C. We use this reversible swelling capability to open and close compartments embedded in a microfluidic chip.Grafting and structuring these hydrogel features relies on thiol-en click chemistry, initiated thermally or by UV irradiation. We have developed methods and microfabrication protocols in order to diversify the substrate materials (from glass to PDMS, COC, PMMA, etc), to expand the structures thickness range (from few microns to a tenth of microns) and to strengthen our knowledge regarding the fabrication impact on the hydrogel’s behavior. A robust protocol of photolithography has finally been worked on allowing the design of any type of 2D features on a large choice of substrates.One of the realistic applications detailed here is the development of microfluidic chips aiming at isolating single cells in hydrogel compartments. (confidential)
Boltyanskiy, Rostislav. "Mechanical Response of Single Cells to Stretch." Thesis, Yale University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10160860.
Повний текст джерелаA living cell is a complex soft matter system far from equilibrium. While its components have definite mechanical properties such as stiffness and viscosity, cells consume energy to generate force and exhibit adaptation by modulating their mechanical properties through regulatory pathways. In this dissertation, we explore cell mechanics by stretching single fibroblast cells and simultaneously measuring their traction stresses. Upon stretch, there is a sudden, drastic increase in traction stresses, often followed by a relaxation over a time scale of about 1 minute. Upon release of stretch, traction stresses initially drop and often recover on a similar time scale of about 1 minute. We show that a minimal active linear viscoelastic model captures essential features of cell response to stretch. This model is most successful in describing the response of cells within the first 30 seconds of stretch. While perturbations of myosin and vinculin change quiescent traction stresses, they surprisingly have no significant impact on the stiffness or viscoelastic timescale of the cells. On longer time scales, cells may show an adaptive response to stretch that contradicts the minimal mechanical model. The probability of an adaptive response is significantly reduced by myosin de-activation and vinculin knockout. Therefore, we find that while vinculin and myosin are not important in determining passive mechanical properties of cells, such as stiffness and viscosity, they play a significant role in the adaptive mechanisms of cell response to stretch. To perform this work, we have built a novel micro stretching device compatible with live cell microscopy and developed a computational tool to analyze data from large traction stresses. Therefore, this dissertation's contribution is two-fold: (1) a novel experimental approach to explore the mechanics of living cells, and (2) a new model and framework for understanding the mechanical response of cells to stretch.
Pagliaro, Sarah Beatriz De Oliveira. "Transcriptional control induced by bcr-abl and its role in leukemic stem cell heterogeneity. Single-Cell Transcriptome in Chronic Myeloid Leukemia: Pseudotime Analysis Reveals Evidence of Embryonic and Transitional Stem Cell States Single Cell Transcriptome in Chronic Myeloid Leukemia (CML): Pseudotime Analysis Reveals a Rare Population with Embryonic Stem Cell Features and Druggable Intricated Transitional Stem Cell States A novel neuronal organoid model mimicking glioblastoma (GBM) features from induced pluripotent stem cells (iPSC) Experimental and integrative analyses identify an ETS1 network downstream of BCR-ABL in chronic myeloid leukemia (CML)." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASQ032.
Повний текст джерелаChronic myeloid leukemia is a clonal hematopoietic malignancy, characterized by the acquisition of the t (9;22) translocation leading to Ph1 chromosome and its counterpart BCR-ABL oncogene, in a very primitive hematopoietic stem cell. CML is a model of targeted therapies as the proof of concept of the feasibility of targeting the tyrosine kinase (TK) activity BCR-ABL using TK inhibitors (TKI) has been shown to lead to major responses and remissions. However, the current problems encountered in these therapies are primitive leukemic stem cells resistance and their persistence which is thought to be related to the heterogeneity of the stem cells at diagnosis leading to clonal selection of cells resisting to TKI therapies. I have applied the technology of single cell transcriptome analysis to CML cells using a panel of genes involved in different pathways combined with trajectory inference analysis to the gene expression pattern. The results showed a transitional stem cell states including embryonic genes identified in CML cells at diagnosis which could contribute to LSC resistance and persistence. Furthermore, the oncoprotein Bcr-Abl is the constitutively active tyrosine kinase produced by the chimeric BCR-ABL gene in chronic myeloid leukemia (CML). The transcriptional targets of Bcr-Abl in leukemic cells have not been extensively studied. A transcriptome experiment using the hematopoietic UT7 cell line expressing BCR-ABL, has identified the overexpression of eukaryotic elongation factor kinase 2 (eEF2K) which plays a major role in the survival of cells upon nutrient deprivation. Overall, the data suggest that overexpression of eEF2K in CML is associated with an increased sensitivity to nutrient-deprivation
Simon-Desbois, Linda. "Development of a microfluidic device for single cell transcriptome analysis." Thesis, Lille 2, 2013. http://www.theses.fr/2013LIL2S007.
Повний текст джерелаIn the post-genomic era, it is now critical to characterize living organisms at the singlecell level. CAGE (Cap Analysis of Gene Expression) is a technology developed by agroup of RIKEN instituteto get genome-wide profile of gene expression. It can beused for profiling of gene expression and identifying the TSS (transcription start site)to analyze promoters architecture. By using the CAGE technology, it could be foundthat different tissues and families of genes differentially use distinct types ofpromoters. Applying CAGE technology against single cells is an ideal way tounderstand life phenomenon based on genome and will have a major impact inbiology. To address this, a novel platform to manipulate single cell and analyze itsown transcriptome with higher precision and efficiency is required.This project aims to develop a microfluidic platform to realize the protocol of CAGEtechnology against single cells with higher-throughput and sensitivity overconventional microtube-based way. For this, we encapsulated single cells inmicrodroplets, lysed them, and performed RT reaction in order to sequence andanalyze their transcriptome
Chen, Peng. "Single cell assays of exocytosis /." free to MU campus, to others for purchase, 2002. http://wwwlib.umi.com/cr/mo/fullcit?p3074384.
Повний текст джерелаTraboulsi, Abdel-Meneem. "Étude à moyen-débit de la localisation d'ARNm dans les cellules humaines." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT117.
Повний текст джерелаMRNA localization was discovered in 1983 in ascidian oocytes and early embryos. Since then many examples of localized RNAs have been found in many organisms, including plants, yeast, fungi, insects, fish and mammals. Localized mRNAs contribute to many biological functions, such as embryonic patterning, asymmetric cell division, cell migration, signaling, neuronal plasticity and others…Until now, only few studies analyzed RNA localization in a systematic manner. Three of them were done in Drosophila, during embryogenesis, oogenesis or larval stage and analyzed around 16000 mRNAs in total. The two other studies were done in mammalian cells and analyzed nearly 1000 mRNAs each. These studies opened a door and raised questions regarding the importance of mRNA localization in human cells and its implication in different biological processes. The goal of my thesis was thus to increase the throughput of single molecule FISH techniques (smFISH) and to study mRNA localization in HeLa cells in a systematic manner.One limitation in smFISH is the cost of the fluorescent oligonucleotide probes, which limits the number of mRNAs that can be analyzed. Therefore, I developed an alternative protocol in which probes for many genes were synthesized as a pool of oligonucleotides (40 per gene in average, more than 12000 in total). Gene-specific probes were then amplified by PCR and converted into single strand by in vitro transcription. I generated a complete protocol, starting from probe design and up to image acquisition. I was interested in studying cell cycle genes. Indeed, cell cycle genes have been extensively studied at the protein level but little is known concerning the localization of their mRNAs. During mitosis, cells go through important morphological modifications and local translation could be a mean of achieving protein localization. This screen is ongoing.In parallel to these experiments, I performed a smFISH based screen on 100 randomly chosen genes and 50 regulators of the G2/M transition of the cell cycle, using a traditional smFISH protocol. In this set-up, I took advantage of a library of HeLa cell lines, in which each cell line contains a bacterial artificial chromosome with the gene of interest tagged with GFP. Therefore, using oligonucleotides hybridizing to the GFP sequence, I could use the same probe set to study the localization of all the tagged mRNAs. A further advantage is that protein localization could be assessed simultaneously. My results indicate that two mRNAs showed a specific localization when screening 100 random genes, and 16 mRNAs among the 50 regulators of the G2/M transition. These mRNAs belong to five localization classes: "blobs", which are cytoplasmic mRNA aggregates; "clusters", which are areas of high local mRNA concentration but where individual mRNA can still be resolved; "nuclear envelope", where mRNAs concentrate around the nuclear envelope; "spindle", which are mRNAs accumulating on the cell division apparatus during mitosis, “spots" which are cytoplasmic mRNA aggregates where individual mRNA can’t be resolved and are bigger than blobs. Interestingly, colocalization between mRNA and GFP, which suggests local translation, was only found for 1 mRNA.These random and targeted screens performed at small-scale show an unexpected frequency and diversity in mRNA localization patterns, therefore pointing to new functions related to this process. This will stimulate future studies aiming at performing screenings at a higher scale
Ben, Meriem Zacchari. "Memory of stress response in the budding yeast Saccharomyces cerevisiae." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC311.
Повний текст джерелаCellular memory is a critical ability displayed by micro-organisms in order to adapt to potentially detrimental environmental fluctuations. In the unicellular eukaryote S. cerevisiae, it has been shown at the population level that cellular memory can take the form of a faster or a decreased response following repeated stresses. We here present a study on how yeasts respond to short, pulsed hyperosmotic stresses at the single-cell level. We analyzed the dynamical behavior of the stress responsive STL1 promoter fused to a fluorescent reporter using microfluidics and fluorescence time-lapse microscopy. We established that pSTL1 displays a dynamical variability in its successive activations following two short and repeated stresses. Despite this variability, most cells displayed a memory of past stresses through a decreased activity of pSTL1 upon repeated stresses. We showed that this memory does not require do novo protein synthesis. Rather, the genomic location is important for the memory since promoter displacement to a pericentromeric chromatin domain leads to its decreased transcriptional strength and to the loss of the memory. Interestingly, our results points towards an unreported involvement of the SIR complex on the activity of pSTL1 only when displaced to the pericentromeric domain in our experimental conditions. This study provides a quantitative description of a cellular memory that includes single-cell variability and points towards the contribution of the chromatin structure in stress memory. Our work could serve as a basis to broader studies on the positioning of stress response genes at subtelomeric positions in the budding yeast, from a genetic point of view as well as an evolutionary one
Svensson, Valentine. "Probabilistic modelling of cellular development from single-cell gene expression." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/267937.
Повний текст джерелаFaddah, Dina Adel. "Single-cell analyses of cellular reprogramming and embryonic stem cells." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/89941.
Повний текст джерелаVita. Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
Three years before the start of this thesis, Yamanaka and Takahashi published a groundbreaking paper entitled "Induced of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors." A mere two scientists reprogrammed somatic cells to an embryonic stem-cell like state (termed induced pluripotent stem cells, iPSCs) by simply overexpressing four transcription factors: Oct4, Sox2, c-Myc, and Klf4. During cellular reprogramming, only a small fraction of cells become iPSCs. Previous analyses of gene expression during reprogramming were based on populations of cells, impeding single-cell level identification of reprogramming events. Using single-cell analysis, we found Esrrb, Utf1, Lin28 and Dppa2 to be predictive markers of reprogramming. We found that single cells exhibit high variation in gene expression early in reprogramming and this heterogeneity decreases are the cell reaches pluripotency. Our results show that a stochastic phase of gene activation is followed by a late hierarchical phase, initiated by activation of the Sox2 locus, leading to the activation of the pluripotency circuitry. Finally, we reprogram cells without Oct4, Klf4, Sox2, c-Myc, and Nanog. Embryonic stem cells (ESCs) are the gold standard comparison for iPSCs. Our investigation of ESCs must continue in parallel to that of iPSCs since we cannot truly understand iPSCs if we do not understand the molecular mechanisms that regulate ESC pluripotency. The homeodomain transcription factor Nanog is a central part of the core pluripotency transcriptional network and plays a critical role in ESC self-renewal. Several reports have suggested that Nanog expression is allelically regulated and that transient downregulation of Nanog in a subset of pluripotent cells predisposes them toward differentiation. Using single-cell gene expression analyses combined with different reporters for the two alleles of Nanog, we show that Nanog is biallelically expressed in ESCs independently of culture condition. We also show that the overall variation in endogenous Nanog expression in ESCs is very similar to that of several other pluripotency markers. Our analysis suggests that reporter-based studies of gene expression in pluripotent cells can be significantly influenced by the gene-targeting strategy and genetic background employed. Our results show that single-cell analysis is essential for deciphering the mechanisms of reprogramming and understanding gene regulation of ESCs, exposing important rarities typically masked by population-based assays.
by Dina Adel Faddah.
Ph. D.
Meehan, Sean. "Structural Stiffness Gradient along a Single Nanofiber and Associated Single Cell Response." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23105.
Повний текст джерелаIn this study using our recently described non-electrospinning fiber manufacturing platform, customized scaffolds of suspended nanofibers are developed to study single cell behavior in a tunable structural stiffness (N/m) environment. Suspended fibers of three different diameters (400, 700 and 1200 nm) are deposited in aligned configurations in two lengths of 1 and 2 mm using the previously described STEP (Spinneret based Tunable Engineered Parameters) platform. These fibers present a gradient of structural stiffness to the cells at constant material stiffness. Single cells attached to fibers are constrained to move along the fiber axis and with increase in structural stiffness are observed to spread to longer lengths, put out longer focal adhesions, have elongated nucleus with decreased migration rates. Furthermore, more than 60% of cell population is observed to migrate from areas of low to high structural stiffness. Additionally dividing cells are observed to round up and daughter cells are observed to migrate away from each other after division. Interestingly, dividing rounded cells are found to be anchored to the fibers through thin protrusions emanating from the focal adhesion sites.
These results indicate a substrate stiffness sensing mechanism that goes beyond the traditionally accepted modulus sensing that cells have been shown to respond to previously. From this work, the importance of structural stiffness in cellular mechanosensing at the single cell-nanofiber scaled warrants consideration of the above factors in accurate design of scaffolds in future.
Master of Science
Wu, Zhanghan. "Understanding molecular and cellular processes using statistical physics." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/27745.
Повний текст джерелаPh. D.
Gielen, Fabrice Matthieu. "Single cell dielectrophoretic trapping for the analysis of cellular membrane dynamics." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9532.
Повний текст джерелаMartineau, Eugénie. "Linking single cell directionality to dynamic multicellular transitions in Myxococcus xanthus : a multiscale analysis." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0089.
Повний текст джерелаThe δ-proteobacteria Myxococcus xanthus has been a model of study for decades for its self-organized behavior as a response of environmental stimuli. It colonizes favorable ecological niches by using surface motility. In particular, this motility allows M.xanthus to predate collectively over prey microorganisms, while under starvation they start a developmental process to form macroscopic fruiting bodies, filled with environmental resistant myxospores. All these multicellular behaviors require a dynamic control of the cell polarity established by the polarity proteins MglA, MglB and RomR. Together, they define the direction of movement of the cell, which can be rapidly inverted by the Frz chemosensory system (reversion). In this thesis work, through combined computational/experimental approaches, we highlight that the regulation system forms a new type of biochemical oscillator, controlled by two proteins RomR and FrzX, which act together through complementary action to trigger the reversion at the lagging pole. The unique architecture of this system allows a wide response to various stimuli, which could be very beneficial for collective cell behaviors. To understand the importance of these transitions, we have developed a new high-resolution single cell assay linking single cMARTINEAU EUGENIE 2018AIXM0089/016ED62 2018/03/21 62 SCES SCHell behaviors to multicellular structures at unprecedented spatial and temporal resolutions. This way, we have investigated the role of the newly identified biochemical oscillator in the multicellular model of predation
Tomba, Caterina. "Primary brain cells in in vitro controlled microenvironments : single cell behaviors for collective functions." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENY039/document.
Повний текст джерелаThe complex structure of the brain is explored by various methods, such as neurophysiology and cognitive neuroscience. This exploration occurs at different scales, from the observation of this organ as a whole entity to molecules involved in biological processes. Here, we propose a study at the cellular scale that focuses on two building elements of brain: neurons and glial cells. Our approach reachs biophysics field for two main reasons: tools that are used and the physical approach to the issues. The originality of our work is to keep close to the in vivo by using primary brain cells in in vitro systems, where chemical and physical environments are controled at micrometric scale. Microelectronic tools are employed to provide a reliable control of the physical and chemical cellular environment. This work focuses on two aspects of brain cell biology: neuronal polarization and glial cell sensitivity to mechanical properties of their environment. As an example, these two issues are involved in injured brains. The first is crucial for the directionality of the transmission of electrical and chemical signals and is associated to a break of symmetry in neuron morphology. The second occurs in recolonization mechanisms of lesions, whose mechanical properties are impaired. During this thesis, quantitative studies are performed on these two cell types, focusing on their growth and their response to geometrical and mechanical constraints. The final aim is to elucidate some molecular mechanisms underlying changes of the cellular structure, and therefore of the cytoskeleton. A significant outcome of this work is the control of the neuronal polarization by a simple control of cell morphology. This result opens the possibility to develop controlled neural architectures in vitro with a single cell precision
Fogelson, Benjamin Marc Feder. "Mechanical Models in Single-Cell Locomotion, Adhesion, and Force Production." Thesis, New York University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10190369.
Повний текст джерелаHere we present the results of two distinct projects in the field of cellular mechanics. In the first project, we describe a non-monotonicity in the scaling of force production in actomyosin stress fibers. We develop a continuum mechanical model to explain that non-monotonicity and, using both analytical and numerical techniques, conclude that the scaling is due to an interaction between different physical lengthscales inherent in the actomyosin force-production system. Using singular perturbation methods, we study the model further to make predictions about the physical conditions under which a cell can break symmetry. In the second project, we explore how lipid flow in the plane of the plasma membrane contributes to membrane translocation during cell migration. By numerically solving the Stokes equations, we quantify the magnitude of the force necessary to generate this flow, and analyze how the presence of transmembrane protein obstacles influences the resulting front-to-rear membrane tension gradient. We make several analytic estimates of the mechanical importance of this membrane tension for cell motility.
Dodeller, Marc. "Analyse par spectrométrie de masse de l'oxygène moléculaire singulet et de protéines potentiellement ciblées au sein de cellules tumorales lors de la thérapie photodynamique." Metz, 2007. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2007/Dodeller.Marc.SMZ0753.pdf.
Повний текст джерелаPhotodynamic therapy (PDT), uses a photosensitizing molecule such as 5,10,15,20-tetrakis(m-hydroxyphenyl) chlorin (m-THPC, Foscan®), a second generation drug which is specially targeted tumoural tissue with a good selectivity, light and oxygen, inducing cell death by necrosis or apoptosis. Firstly, our studies consist to detect by MALDI-TOF/MS, in intact HT29 cells (adenocarcinoma human colon), singlet oxygen generated by Foscan® (Biolitec Pharma Ldt, Dublin, Irlande) and the protein cells distribution after PDT treatment. A MALDI-TOF mass spectrometer was used to highlight ortho-benzoïbenzene (o-BB) resulting from the reaction between singlet oxygen generated by Foscan® during PDT treatment and 1,3-diphenylisobenzofurane (1,3-DPBF, a specific singlet oxygen quencher). This technique allows the following of the in situ behaviour of the photosensitizer and to detect the presence of singlet oxygen directly in intact HT29 cells. We have also studied the oxidative stress induced by PDT treatment on HT29 cells. After 2D gel SDS-PAGE step in order to observe the protein distribution, proteomic approach is carried out by MALDI-FTICR mass spectrometry (9,4 T, Ion Spec Varian, California). Thnaks to ImageMaster 2D platinium software, we are able to visualize under expression of some proteins. The proteinic finger printings is then characterized by MALDI-FT-ICR/MS and the first results indicate that proteins of dislfide Isomerase family should be implied in PDT processes. MALDI-TOF/MS and MALDI-FTICRMS (9,4 T) appear to be a sensitive and reliable analytical tool (add to UV/Visible anf fluorescence spectroscopy) for the mechanism of PDT understanding
Marcy, Guillaume. "Etude des spécificités transcriptionnelles et de la compétence des progéniteurs neuraux postnataux du cerveau antérieur chez la souris." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEP070/document.
Повний текст джерелаDuring development, a remarkable coordination of molecular and cellular events leads to the generation of the cortex, which orchestrates most sensorimotor and cognitive functions. Cortex development occurs in a stepwise manner: radial glia cells (RGs) - the neural stem cells (NSCs) of the developing brain - and progenitor cells from the ventricular zone (VZ) and the subventricular zone (SVZ) sequentially give rise to distinct waves of nascent neurons that form cortical layers in an inside-out manner. Around birth, RGs switch fate to produce glial cells. A fraction of neurogenic RGs that lose their radial morphology however persists throughout postnatal life in the subventricular zone that lines the lateral ventricles. These NSCs give rise to different subtypes of olfactory bulb interneurons and glial cells, according to their spatial origin and location within the postnatal SVZ. These observations raise important unresolved questions on 1) the transcriptional coding of postnatal SVZ regionalization, 2) the potential of postnatal NSCs for cellular regeneration and forebrain repair, and 3) the lineage relationship and transcriptional specificities of postnatal NSCs and of their progenies. My PhD work built upon a previously published comparative transcriptional study of defined microdomains of the postnatal SVZ. This study highlighted a high degree of transcriptional heterogeneity within NSCs and progenitors and revealed transcriptional regulators as major hallmarks sustaining postnatal SVZ regionalization. I developed bioinformatics approaches to explore these datasets further and relate expression of defined transcription factors (TFs) to the regional generation of distinct neural lineages. I then developed a model of targeted ablation that can be used to investigate the regenerative potential of postnatal progenitors in various contexts. Finally, I participated to the development of a pipeline for exploring and comparing select populations of pre- and postnatal progenitors at the single cell level. Objective 1: Transcriptomic as well as fate mapping were used to investigate the relationship between regional expression of TFs by NSCs and their acquisition of distinct neural lineage fates. Our results supported an early priming of NSCs to produce defined cell types depending of their spatial location in the SVZ and identified HOPX as a marker of a subpopulation biased to generate astrocytes. Objective 2: I established a cortical lesion model, which allowed the targeted ablation of neurons of defined cortical layers to investigate the regenerative capacity and appropriate specification of postnatal cortical progenitors. Quantitative assessment of surrounding brain regions, including the dorsal SVZ, revealed a transient response of defined progenitor populations. Objective 3: We developed a transgenic mouse line, i.e. Neurog2CreERT2Ai14, which allowed the conditional labeling of birth-dated cohorts of glutamatergic progenitors and their progeny. We used fate-mapping approaches to show that a large fraction of Glu progenitors persist in the postnatal forebrain after closure of the cortical neurogenesis period. Postnatal Glu progenitors do not accumulate during embryonal development but are produced by embryonal RGs that persist after birth in the dorsal SVZ and continue to give rise to cortical neurons, although with low efficiency. Single-cell RNA sequencing revealed a dysregulation of transcriptional programs, which correlates with the gradual decline in cortical neurogenesis observed in vivo. Altogether, these data highlight the potential of transcriptomic studies to unravel but also to approach fundamental questions such as transcriptional changes occurring in a population of progenitors over time and participating to changes in their fate potential. This knowledge will be key in developing innovative approaches to recruit and promote the generation of selected cell types, including neuronal subtypes in pathologies
Tamra, Amar. "Spectroscopie diélectrique hyperfréquence de cellules individualisées sous électroporation." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30011/document.
Повний текст джерелаElectroporation is a physical process that consists in applying electric field pulses to transiently or permanently permeabilize the plasma membrane. This phenomenon is of great interest in the clinical field as well as in the industry because of its various applications, in particular electrochemotherapy which combines electrical pulses with the administration of a cytotoxic molecule in the treatment of tumors. The evaluation of this phenomenon is raditionally carried out using optical and biochemical methods (microscopy, flow cytometry, biochemical test). They are very effective but require the use of a wide range of fluorochromes and markers, which can be laborious and costly to implement, while being invasive to the cells. In recent years, the development of new biophysical tools for the study of electroporation has taken place, such as dielectrophoresis and impedance spectroscopy (low frequency). In addition to the ease of implementation, these methods are of interest in the study of membrane modifications of the cell. Hence the advantage of operating beyond the GHz, in the range of microwaves, for which the cytoplasmic membrane becomes transparent and the intracellular content is exposed. The extraction of the relative permittivity as a result of the electromagnetic field / biological cell interaction then reflects the cell state. This technique, microwave dielectric spectroscopy, is a relevant method for analyzing the effects of electroporation on cell viability. Moreover, it does not require any use of the exogenous molecules (non-invasive) and the measurements are directly carried out in the culture medium of the cells. Two objectives were defined during this thesis whose work is located at the interface between three scientific fields: cellular biology, microwave electronics and micro-technologies. The first objective concerns the transposition of conventional electroporation to the micrometric scale, which has shown an efficiency as efficient as the first. The second part of the work concerns the study by HighFrequency dielectric spectroscopy of cells subjected to different electrical treatments (combined or not with a cytotoxic molecule). This work presents a statistical power and shows a very good correlation (R2> 0.94) with standard techniques used in biology, which biologically validates the HF analysis method in the context of electroporation. This work also shows that microwave dielectric spectroscopy proves to be a powerful technique capable of revealing cell viability following chemical and / or electrical treatment. They open the way to 'non-invasive' analysis by hyper-frequency dielectric spectroscopy of electroporated cells in situ
Timofeeva, Yulia. "Oscillations and waves in single- and multi-cellular systems with free calcium." Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/33829.
Повний текст джерелаGrosselin, Kevin. "Cartographie épigénétique de cellules cancéreuses résistantes rares par microfluidique en gouttelettes." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLET015.
Повний текст джерелаThe dynamic nature of chromatin and transcriptional features play a critical role in normal differentiation and are expected to contribute to tumor evolution. Studying the heterogeneity of chromatin alterations with single-cell resolution is mandatory to understand the contribution of epigenetic plasticity in cancer.In this thesis, I describe a droplet microfluidics approach to profile chromatin landscapes of thousands of cells at single-cell resolution, with an unprecedented coverage of 10,000 loci per cell.The system was evaluated to profile histone modifications associated with active (H3K4me3) and inactive transcription (H3K27me3) of human B cells and T cells, and revealed that >99% of the cells were correctly assigned to one cell type, defining distinct chromatin states of immune cells with high accuracy.In patient-derived xenograft (PDX) models of breast cancer with acquired drug resistance, the system enabled the detection of a rare subpopulation of cells in the untreated, drug-sensitive tumors with chromatin features characteristic of resistant cancer cells. These cells had lost chromatin marks (H3K27me3) associated with stable transcriptional repression for a number of genes known to promote resistance, potentially priming them for transcriptional activation.These results highlight the potential selection of cells with specific chromatin marks in response and in resistance to cancer therapy
Foulon, Sophie. "Développement du séquençage ARN ciblé sur cellules uniques en microfluidique de gouttes et applications." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLET037.
Повний текст джерелаSingle cells technologies were introduced a few years ago and have been dramatically evolving ever since. These technologies have revolutionized biology, making it possible to better understand how heterogeneous cell systems works. For example, they permit to discover and follow cell subtypes, with applications in oncology or neurobiology. We have developed a technology to study the expression profile of genes of interest at the level of a single cell, using droplet-based microfluidics. By limiting the number of genes studied compared to commercial whole-transcriptome technologies, the targeted approach has several potential benefits: gaining deeper sequencing, increasing the number of cells studied, optimizing detection for low levels of expression, while reducing the complexity of data and costs. Targeting is sometimes essential, especially when the RNAs do not carry a generic primer sequence, as in the case of viral RNAs. Two applications are presented: the analysis of inflammation of the immune cells of the brain in the early stages of development, as well as the study of genetic recombination in the virus
Park, Clara S. M. Massachusetts Institute of Technology. "A multiplex platform based on cellular barcoding for measuring single cell drug susceptibility." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113754.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (pages 43-44).
Predicting individual patient response to cancer drugs has been challenging. As many anticancer drugs aim to modulate cell deaths or growth inhibition, a useful assay for drug susceptibility would require direct assessment of phenotypic changes to cells upon drug treatment, such as cell viability or growth rate. Previously, the serial microfluidic mass sensor arrays have been used to measure single-cell mass accumulation rates over ~20 minute intervals to assess drug susceptibility. Here, we present a multiplexing platform that allows evaluation of multiple drug response conditions in a single experiment by utilizing fluorescent barcodes based on cell surface labeling. Fluorescence microscopy was integrated with the serial microfluidic mass sensor arrays to match a given barcode (which corresponds to a drug condition) with its mass accumulation rate as each cell flows through the microfluidic channel. To validate our approach, we show that the dynamics of drug response can be obtained from a single experiment by multiplexing drug treatment durations. Our validation highlights the capability of our platform to both eliminate measurement bias due to time differences in drug exposure and reduce the operation time when compared to standard time point assays.
by Clara Park.
S.M.
Parutto, Pierre. "Statistical analysis of single particle trajectories reveals sub-cellular nanodomain organisation and function." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEE055.
Повний текст джерелаSingle-Particle Trajectories (SPTs) obtained from super-resolution microscopy allow to track proteins with nanometer precision in living cells and are used in neuroscience and cellular biology. In this thesis, I was interested in the high-density nanodomains found in these trajectories that can be modeled as potential wells. To characterize them, I developed a new hybrid method based on the point density and local drift field and compared it to the other state-of-the-art methods. Then, I used it to identify transient potential wells in SPTs of voltage-gated calcium channels (CaV) contributing to a better understanding of the role of the different CaV splice variants in synaptic transmission. In another study, I looked at SPTs from Endoplasmic Reticulum (ER) luminal resident proteins where I developed a method to reconstruct the network from trajectories and used it to characterize the luminal motion as a jump-diffusion process, which allows for a better redistribution of the luminal content than the previously assumed diffusive model. Finally, I discuss other analyses of motions for lysosome-ER interactions, CaV2.1 channels at drosophila’s neuromuscular junctions and the description of the motion of the constituent proteins of the NuRD chromatin remodeling complex
Woringer, Maxime. "Tools to analyze single-particle tracking data in mammalian cells." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS419.
Повний текст джерелаThis work aims at providing tools to dissect the regulation of transcription in eukaryotic cells, with a focus on single-particle tracking of transcription factors in mammalian cells. The nucleus of an eukeryotic cell is an extremely complex medium, that contains a high concentration of macromolecules (DNA, RNA, proteins) and other small molecules (ATP, etc). How these molecules interact with transcription factors, and thus influence transcription rates is an area of intense investigations. Although some of these interactions can be captured by regular biochemistry, many of them, including weak, non-covalent interactions remain undetected by these methods. Live-cell imaging and single-particle tracking (SPT) techniques are increasingly used to characterize such effects. The inference of biophysical parameters of a given transcription factor (TF), such as its diffusion constant, the number of subpopulations or its residence time on DNA, are crucial to understanding how TF dynamics and transcription intertwine. Accurate and validated SPT analysis tools are needed. To be used by the community, SPT tools should not only be carefully validated, but also be easily accessible to non-programmers. They should also be designed to take into account known biases of the imaging techniques. In this work, we first propose a tool, accessible through a web interface, based on the modeling of the diffusion propagator. We validate it extensively and show that it exhibits state-of-the art performance. We apply this tool to two experimental settings: (1) the study of catalysis-enhanced diffusion in-vitro and (2) the analysis of the dynamics of the c-Myc transcription factor in mammalian cells
Boddington, Christopher. "An interdisciplinary analysis of inflammatory signalling dynamics in single cells." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/an-interdisciplinary-analysis-of-inflammatory-signalling-dynamics-in-single-cells(c2cad496-b993-42d9-b4fd-2c16e1f9fd42).html.
Повний текст джерелаWen, Mary Mei. "New strategies for tagging quantum dots for dynamic cellular imaging." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52150.
Повний текст джерелаMorgan, Kenneth J. "Design and Analysis of Four Architectures for FPGA-Based Cellular Computing." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/35578.
Повний текст джерелаMaster of Science
Sedlachek, Kelly M. "The effect of hemicelluloses and cyclic humidity on the creep of single fibers." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/5802.
Повний текст джерелаHung, Yin Pun. "Single Cell Imaging of Metabolism with Fluorescent Biosensors." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10147.
Повний текст джерелаZuttion, Francesca. "Effet inhibiteur des glycoclusters dans l'adhésion bactérienne des Pseudomonas aeruginosa caractérisé par microscopie à force atomique : de la molécule à la cellule." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEC031/document.
Повний текст джерелаPseudomonas aeruginosa (PA) is a human opportunistic pathogen responsible for 20% -30% of nosocomial infections in French hospitals. For healthy people, it presents no real danger, but for people with cystic fibrosis disease and immune-compromised patients, it is the leading cause of mortality and lung infections. PA has developed antibiotic multi-resistant strains and new and more effective therapeutic approaches are needed. It binds to the surface of the host cells by an interaction between proteins (lectins) present on the membrane and sugars of the host-cell membrane. The lectin-sugar interaction plays an important role in adherence of the bacteria and in the manufacture of a pathogenic biofilm.A new therapeutic approach is to create synthetic molecules (glycoclusters) of greater affinity than the natural sugars present on the cells. To this aim, more than 150 glycoclusters have been synthetized and screened to find the best candidate to inhibit the bacteria infection process. Some of them have been selected and studied by Atomic Force Microscopy (AFM). In particular, this thesis is devoted to study the lectin-glycocluster and cell-bacteria interactions by AFM. The combination of AFM imaging with molecular dynamic simulations let understanding the role of the geometry of the glycoclusters on the complex formation, while AFM spectroscopy accesses the lectin-glycocluster interaction forces at the molecular and cellular levels. The reduction of bacterial adhesion has been observed upon the addition of the glycocluster. This confirms the anti-adhesive properties of the glycocluster and validates the procedure. The ultimate goal is the identification of the best glycoclusters in order to develop new drugs
Walter, Ulrich Josef. "On the molecular mechanisms of β cell destruction in autoimmune diabetes : a single cell approach". Paris 5, 2001. http://www.theses.fr/2001PA05N033.
Повний текст джерелаCarroll, Jean. "Investigating aprataxin function : roles in DNA single strand break repair and functional cellular effects." Thesis, University of Sussex, 2013. http://sro.sussex.ac.uk/id/eprint/46135/.
Повний текст джерелаGarcia, Ellen Brook. "Investigating the cellular toxicology of silver nanoparticles using a single-cell, mitosis-focused approach." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/102095.
Повний текст джерелаMaster of Science
Multiple agencies, including the U.S. Environmental Protection Agency and the National Academy of Science, are urging for a radical paradigm shift from standard, whole-animal testing to alternative and novel technologies. To meet this urgent need, we aimed to develop a new, cell division-focused toxicity assay by investigating the mechanism of toxicity from silver nanoparticles (AgNPs) on human retinal pigment epithelial (RPE-1) cells. Cultured RPE-1 cells were treated with varying concentrations of AgNPs and live-cell microscopy was used to analyze the behavior of cells undergoing cell division over a 24 hour time period. Physical interaction between cells and particles was visually observed and 100% of treated cells appeared to engulf particles. We found that higher concentrations of AgNPs resulted in large numbers of cells stalling in mitosis and/or dying. In contrast, untreated cells displayed normal mitotic behavior. High-resolution fluorescence microscopy performed in chronically treated cell populations identified an increased percentage of binucleated cells. Further live-cell analysis indicated that one major cell division defect could explain the binucleated cell phenotype. Indeed, treated cells failed cytokinesis (cytoplasmic division following mitotic chromosome segregation) more often than control cells. Overall, our results indicate that AgNPs specifically impair cell division, not only further confirming toxicity to human cells, but also revealing specific, previously unreported toxicity mechanisms and highlighting the propagation of adverse phenotypes within the cell population after exposure. Furthermore, this work illustrates that cell division-based assays and ingle-cell analysis could greatly benefit chemical safety experimentation in the future.
Lanoiselée, Yann. "Revealing the transport mechanisms from a single trajectory in living cells." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX081/document.
Повний текст джерелаThis thesis is dedicated to the analysis and modeling of experiments where the position of a tracer in the cellular medium is recorded over time. The goal is to be able to extract as much information as possible from a single experimentally observed trajectory. The main challenge is to identify the transport mechanisms underlying the observed movement. The difficulty of this task lies in the analysis of individual trajectories, which requires the development of new statistical analysis tools. In the first chapter, an overview is given of the wide variety of dynamics that can be observed in the cellular medium. In particular, a review of different models of anomalous and non-Gaussian diffusion is carried out. In the second chapter, a test is proposed to reveal weak ergodicity breaking from a single trajectory. This is a generalization of the approach of M. Magdziarz and A. Weron based on the time-averaged characteristic function of the process. This new estimator is able to identify the ergodicity breaking of continuous random walking where waiting times are power law distributed. By calculating the average of the estimator for several subdiffusion models, the applicability of the method is demonstrated. In the third chapter, an algorithm is proposed to recognize the different phases of an intermittent process from a single trajectory (e.g. active/passive transport within cells, etc.).This test assumes that the process alternates between two distinct phases but does not require any hypothesis on the dynamics of each phase. Phase changes are captured by calculating quantities associated with the local convex hull (volume, diameter) evaluated along the trajectory. It is shown that this algorithm is effective in distinguishing states from a large class of intermittent processes (6 models tested). In addition, this algorithm is robust at high noise levels due to the integral nature of the convex hull. In the fourth chapter, a diffusion model in a heterogeneous medium where the diffusion coefficient evolves randomly is introduced and solved analytically. The probability density function of the displacements presents exponential tails and converges towards a Gaussian one at long time. This model generalizes previous approaches and thus makes it possible to study dynamic heterogeneities in detail. In particular, it is shown that these heterogeneities can drastically affect the accuracy of measurements made by time averages along a trajectory. In the last chapter, single-trajectory based methods are used for the analysis of two experiments. The first analysis carried out shows that the tracers exploring the cytoplasm show that the probability density of displacements has exponential tails over periods of time longer than the second. This behavior is independent of the presence of both microtubules and the actin network in the cell. The trajectories observed therefore show fluctuations in diffusivity, indicating for the first time the presence of dynamic heterogeneities within the cytoplasm. The second analysis deals with an experiment in which a set of 4mm diameter discs was vibrated vertically on a plate, inducing random motion of the disks. Through an in-depth statistical analysis, it is demonstrated that this experiment is close to a macroscopic realization of a Brownian movement. However, the probability densities of disks’ displacements show deviations from Gaussian which are interpreted as the result of inter-disk shocks. In the conclusion, the limits of the approaches adopted as well as the future research orientation opened by this thesis are discussed in detail
Bost, Pierre. "Decoding cellular communications and interactions between immune cells by using single-cell approaches." Electronic Thesis or Diss., Sorbonne université, 2020. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2020SORUS020.pdf.
Повний текст джерелаCellular communications are essential to the proper functioning of multi-cellular organisms, particularly in order to adapt to a constantly changing environment. The cells of the immune system are no exception to this rule, but the interactions between immune cells remain little known and complicated to study. The recent emergence of 'single cell' sequencing technologies represents a unique opportunity to study these communications. In this thesis, different experimental and analytical approaches have been developed to study these communications on a single cell scale. These strategies were then applied to different disease contexts, including COVID-19, Alzheimer's disease or immunisation with inactivated pathogens, and identified previously unknown or poorly understood cellular communication pathways. However, the effectiveness of these approaches is limited by the lack of information on cell location and further work integrating such data will be essential to go further in the dissection of immune cell communications
Kelich, Joseph M. "Single-Molecule Studies on Nuclear Pore Complex Structure and Function." Diss., Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/511772.
Повний текст джерелаPh.D.
Nuclear pore complexes (NPCs) are large macromolecular gateways embedded in the nuclear envelope of Eukaryotic cells that serve to regulate bi-directional trafficking of particles to and from the nucleus. NPCs have been described as creating a selectively permeable barrier mediating the nuclear export of key endogenous cargoes such as mRNA, and pre-ribosomal subunits as well as allow for the nuclear import of nuclear proteins and some viral particles. Remarkably, other particles that are not qualified for nucleocytoplasmic transport are repelled from the NPC, unable to translocate. The NPC is made up of over 30 unique proteins, each present in multiples of eight copies. The two primary protein components of the NPC can be simplified as scaffold nucleoporins which form the main structure of the NPC and the phenylalanine-glycine (FG) motif containing nucleoporins (FG-Nups) which anchor to the scaffold and together create the permeability barrier within the pore. Advances in fluorescence microscopy techniques including single-molecule and super-resolution microscopy have made it possible to label and visualize the dynamic components of the NPC as well as track the rapid nucleocytoplasmic transport process of importing and exporting cargoes. The focus of this dissertation will be on live cell fluorescence microscopy application in probing the dynamic components of the NPC as well as tracking the processes of nucleocytoplasmic transport.
Temple University--Theses
Autissier, Patrick. "Phénotypage des cellules immunitaires par cytométrie en flux multiparamétrique : un outil indispensable dans l’immunopathologie du Sida." Thesis, Paris, CNAM, 2010. http://www.theses.fr/2010CNAM0726/document.
Повний текст джерелаMonitoring changes in immune cell populations such as lymphocytes, monocytes and dendritic cells (DC) during infectious diseases like human immunodeficiency virus (HIV) or its counterpart in rhesus monkeys (SIV) is crucial. Thanks to recent technological advances in flow cytometry, it is now possible to measure and analyze simultaneously up to 14 individual parameters at the single cell level.The goal of this work is to develop 2 multicolor flow cytometry panels comprising of 12 antibodies, allowing measuring simultaneously the main immune cells population, respectively in humans and rhesus monkeys. After 2 years of development and optimization, we can now measure precisely all the main actors of the immune system, that is CD4+ and CD8+ T lymphocytes, B lymphocytes, NK and NKT cells, the 3 monocyte subsets, and all the dendritic cell subsets known today, by using a multicolor flow cytometry approach. This assay is done on whole blood, it is rapid to do, it does not involve a cell isolation technique, and it requires only a minimum amount of blood. Moreover, the analysis of each population is much more precise because of a minimum contamination between different cell populations. The advantage of this work is to study interactions between different cell populations of immune cells during HIV infection in humans, or SIV infection in monkeys, or potentially other diseases, and in particular to better understand the important role that dendritic cells might play in disease progression
Bonnaffoux, Arnaud. "Inférence de réseaux de régulation de gènes à partir de données dynamiques multi-échelles." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEN054/document.
Повний текст джерелаInference of gene regulatory networks from gene expression data has been a long-standing and notoriously difficult task in systems biology. Recently, single-cell transcriptomic data have been massively used for gene regulatory network inference, with both successes and limitations.In the present work we propose an iterative algorithm called WASABI, dedicated to inferring a causal dynamical network from timestamped single-cell data, which tackles some of the limitations associated with current approaches. We first introduce the concept of waves, which posits that the information provided by an external stimulus will affect genes one-byone through a cascade, like waves spreading through a network. This concept allows us to infer the network one gene at a time, after genes have been ordered regarding their time of regulation. We then demonstrate the ability of WASABI to correctly infer small networks, which have been simulated in-silico using a mechanistic model consisting of coupled piecewise-deterministic Markov processes for the proper description of gene expression at the single-cell level. We finally apply WASABI on in-vitro generated data on an avian model of erythroid differentiation. The structure of the resulting gene regulatory network sheds a fascinating new light on the molecular mechanisms controlling this process. In particular, we find no evidence for hub genes and a much more distributed network structure than expected. Interestingly, we find that a majority of genes are under the direct control of the differentiation-inducing stimulus. Together, these results demonstrate WASABI versatility and ability to tackle some general gene regulatory networks inference issues. It is our hope that WASABI will prove useful in helping biologists to fully exploit the power of time-stamped single-cell data
Marra, Vincenzo. "Cellular and molecular mechanisms of different memory phases after single-trial classical conditioning in Lymnaea." Thesis, University of Sussex, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505909.
Повний текст джерелаChen, Wenli. "Spectroscopie diélectrique hyperfréquence de cellules uniques cancéreuses : de l'optimisation du capteur en sensibilité et répétabilité jusqu'au suivi en temps réel de stimuli chimiques." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30219/document.
Повний текст джерелаThe measurement of biological cells is a routine step in many biological investigations. Current techniques used by biologists are mainly based on staining or fluorescent labelings, which provide very precise and effective molecular and cellular observations. Within this context, the microwave dielectric spectroscopy for cell analysis represents a new and attractive method, due to the lack of cells preparation and manipulation, without adding chemicals that could interfere with other cellular constituents. Its compatibility with the analysis of single-cells, potentially in real-time monitoring, constitute also two major assets of the analysis technique. This PhD thesis therefore focused on the optimization of a microfluidic and microwave based biosensor, which is dedicated to the dielectric spectroscopy of individual biological cells, and the development of its metrology to assess the dielectric behavior of cells subjected to chemical stimuli. After a state of the art on the current techniques available to analyze single cells, we focused on the optimization of the microwave biosensor to improve its performances in terms of sensitivity and repeatability. These optimizations dealt with the microfabrication process, the component architecture through the investigation of single cell loading efficacy as well as an electromagnetic parametric study. These developments were validated first experimentally with the measurement of polystyrene beads, which present a simplified dielectric model compared to the complexity of a biological cell, followed then by living individual cells in their culture medium. The test bench was also optimized to allow the dielectric measurement of cells over time, and especially in response to a chemical stimulus. The reaction kinetics of a single-cell subjected to saponin was recorded automatically for different cells. This work opens the door to single-cell analysis with microwave dielectric spectroscopy of complex biological processes in real-time
Claudel, Julien. "Spectroscopie d'impédance électrique par biocapteur à micro-électrodes : application à la cytométrie de flux de cellules sanguines." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0169/document.
Повний текст джерелаThis thesis focuses on the implementation and validation of a microfluidic bioimpedance sensor for cytometric measures in the frequency range ( 100kHz - 10MHz ) of biological cells ( blood cells) combined with a microfluidic device. The first chapter introduces the electrical and dielectric properties of living tissues and summarizes the state of the art. The effects of each element of the cells on the overall measured impedance are described, as well as the associated models. A state of the art, on the bioimpedance macroscopic measurements unit cell is outlined in the second chapter. Measurements by flow cytometry and the possible use of surface acoustic wave (SAW) devices as actuators are also studied. The third chapter deals with analytical modeling and simulation by the finite element method of unit cells by microelectrodes of different geometries. 3D simulations were done showing the best configuration for the electrodes design. The results of this section were used to determine the best geometry, their sensibilities, and their answers. The sensor design is described in the fourth chapter. Technological constraints related to its micro- fabrication techniques feasibility and biocompatibility of materials are developed. Flows validation tests were done and are described. The fifth and final chapter focuses on the measurement of cells and particles. In a first step, calibration tests were carried out to determine the form factor of the electrodes and the parasitic impedances. Measurements on cells and particles were used to validate the results obtained in simulation, as well as discrimination based particles tested their dimensions
Vig, Dhruv Kumar. "Spanning the Continuum: From Single Cell to Collective Migration." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/566259.
Повний текст джерелаEid, Joelle. "Etude du relargage du VIH-1 en temps réel à l'échelle de la cellule unique par la Viro-fluidique." Thesis, Université de Montpellier (2022-….), 2022. http://www.theses.fr/2022UMONT007.
Повний текст джерелаUpon its entry, HIV-1 replicates and produces new viral particles that are released into the extracellular environment. The crucial step of virus release remains poorly understood because it requires the study at the single cell level. Indeed, quantification of viral production from cell populations with very heterogeneous HIV-1 replication kinetics would give approximate results. This is why we have developed a microfluidic approach that allows the study of HIV-1 release dynamics in real-time at the single cell level. In this study, continuous microfluidics was combined to the virology in order to develop a sensitive and reliable technology to visualize and quantify virus production by a single cell. Three types of chips were fabricated: the trapping chip allowed us to determine the physical and biological parameters that ensure single cell trapping (~10 µm) producing VLPs-GFP. The detection chip, whose performance was compared with the Nanoparticle Tracking Analysis technique, proved to be a valuable tool for accurate and reproducible quantification of fluorescent VLPs (~140 nm) at the single particle scale in cell culture supernatants. The multiplex chip, which combines the two previous chips, allowed us to study in real-time the virus release kinetics at the single cell scale. VLPs-GFP producing HeLa and HEK 293 cell lines were used as study models. For the first time, viral production kinetics could be measured with an average of 50 VLPs / cell / h that was validated by the measurement of viruses produced by the same cells grown in culture dish, confirming the reliability and sensitivity of our approach. Interestingly, the release kinetics profile shows a periodic process (period ~4min) that could be explained by the presence of one or more limiting steps in the virion biogenesis mechanism. The new tools developed here provide novel information on the kinetics of HIV-1 salting-out. They can be used or easily adapted for the study of other pathogens or extracellular vesicles
Fougeron, Denis. "Etude et mise en oeuvre de cellules résistantes aux radiations dans le cadre de l'évolution du détecteur à pixels d'Atlas technologie CMOS 65 nm." Electronic Thesis or Diss., Toulon, 2020. http://www.theses.fr/2020TOUL0005.
Повний текст джерелаThis study is inside an international collaboration context, RD53, which its goal is to provide to the scientific community an electronic front-end for the readout of the future pixel detector in 2022. The 65 nm technology chosen by the collaboration will have to be operational in a highly radioactive environment (10 MGray) for five years without maintenance operation.Two experimental approaches are described in this thesis: 1. Irradiation studies were carried out to estimate the dose tolerance (TID) of the 65 nm process to fix all essentials design rules for digital and analog cells implanted in the final circuit. Test vehicles (PCM) were defined for irradiation using an X-ray source (10 keV - 3 kW) to estimate dose effects. The results we obtained are summarized in the document. 2. In order to optimize the tolerance of memories to the SEE effects, several ASIC prototypes havebeen designed. These prototypes include different architectures for irradiation characterization. Several irradiation campaigns have been carried out using a heavy ion beam and a proton beam in order to a cross-section as accurate as possible
Sarma, Ashapurna. "A Single Molecule Study of Calcium Effect on Nuclear Transport." Bowling Green State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1282326584.
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