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Статті в журналах з теми "Analyses en cellules uniques":
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Lacoux, C., M. Truchi, J. Fassy, I. Manosalva-Pena, M. Gautier, V. Magnone, K. Lebrigand, et al. "Analyse des longs ARN non codants régulés par l’hypoxie dans les cellules d’adénocarcinome pulmonaire à l’aide d’un crible basé sur l’interférence CRISPR sur cellules uniques." Revue des Maladies Respiratoires 40, no. 2 (February 2023): 122–23. http://dx.doi.org/10.1016/j.rmr.2022.11.029.
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Dariane, Charles, Manon Baures, Julien Anract, Nicolas Barry Delongchamps, Jacques-Emmanuel Guidotti, and Vincent Goffin. "Progéniteurs luminaux prostatiques." médecine/sciences 39, no. 5 (May 2023): 429–36. http://dx.doi.org/10.1051/medsci/2023058.
Анотація:
Les traitements médicaux de l’hyperplasie bénigne et du cancer de la prostate reposent essentiellement sur l’inhibition de la signalisation androgénique. Bien qu’initialement efficaces, ces traitements sont tôt ou tard confrontés à une résistance thérapeutique. Des données récentes de séquençage d’ARN sur cellules uniques montrent que les cellules luminales survivant à la déprivation androgénique dans ces contextes pathologiques présentent un profil moléculaire semblable à celui de cellules luminales progénitrices, présentes en faible quantité dans un contexte physiologique. Ce profil moléculaire pourrait constituer un hub de résistance à la castration et résulter, en partie, de la reprogrammation des cellules luminales tumorales. L’inhibition thérapeutique de cette plasticité cellulaire constitue une piste prometteuse pour limiter la progression du cancer prostatique.
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Isaac, Juliane, Mélodie M. Clerc, François C. Ferré, and Benjamin P. J. Fournier. "Les cellules mésenchymateuses orales, une niche spécifique, du développement à la régénération." médecine/sciences 40, no. 1 (January 2024): 24–29. http://dx.doi.org/10.1051/medsci/2023191.
Анотація:
Les tissus muqueux et osseux oraux présentent des propriétés uniques. Les fibroblastes de la muqueuse orale et les ostéoblastes des mâchoires, issus des crêtes neurales crâniennes, jouent un rôle clé dans la cicatrisation/réparation. Ces cellules expriment un répertoire spécifique de gènes associés à leurs propriétés régénératives, mais aussi liés aux maladies rares crâniofaciales. La connaissance de ces tissus ouvre des perspectives cliniques pour la régénération tissulaire et la réparation des défauts osseux et muqueux. Ces avancées multidisciplinaires ont aussi un impact prometteur sur la prise en charge des maladies liées au parodonte et sur l’amélioration de la santé bucco-dentaire.
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Remacle, Françoise, and Raphael D. Levine. "Prédiction de la réponse moléculaire à des perturbations mesurée sur des cellules uniques." médecine/sciences 30, no. 12 (December 2014): 1129–35. http://dx.doi.org/10.1051/medsci/20143012016.
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Lardenois, A., B. Evrard, A. Suglia, S. Léonard, L. Lesné, I. Coiffec, B. Jégou, S. Mazaud-Guittot, F. Chalmel, and A. D. Rolland. "Nouveaux acteurs de la différenciation gonadique normale et pathologique, approches cellules uniques chez l’Homme." Annales d'Endocrinologie 82, no. 5 (October 2021): 225. http://dx.doi.org/10.1016/j.ando.2021.07.020.
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Grandjean-Closson, Eva, Camille Heckmann, Corentin Le Coz, Isaline Louvet, Matthieu Neri, and Corine Bertolotto. "L’analyse des mélanomes uvéaux primaires à l’aide de la technique de séquençage d’ARN de cellules uniques." médecine/sciences 38, no. 8-9 (August 2022): 737–39. http://dx.doi.org/10.1051/medsci/2022113.
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Achille, Tadaha Moffo. "Perception De L’échec Et Motivation Académique Des Etudiants En 2e Année En Faculté De Lettres Et Des Sciences Humaines A l’Université De Douala." Journal of Advanced Psychology 5, no. 2 (March 17, 2024): 16–32. http://dx.doi.org/10.47941/japsy.1730.
Анотація:
But : L’examen de l’influence de la perception de l’échec sur la motivation scolaire des étudiants est l’objectif que se donne cet article.
Méthodologie : Pour atteindre celui-ci, les données de l’enquête de terrain auprès de 84 étudiants issus de la deuxième année en Faculté de Lettres et des Sciences Humaines (FLSH) à l’Université de Douala en situation d’échec sont soumises à des analyses descriptives et inférentielles.
Résultats : Les résultats du rhô de Spearman obtenus de l’analyse du questionnaire d’autoévaluation et du « motivomètre » relèvent que le niveau de motivation scolaire est très bas chez ces étudiants et cela semble dû à une mauvaise perception qu’ils ont construite autour de leur échec précédent. En effet, les analyses ont montré un effet positif et significatif des représentations sociales de l’échec, des clichés du nombre d’échec et des croyances autour de l’échec sur la motivation scolaire chez ces étudiants. Dès lors, il semble nécessaire pour l’Etat et les Universités en place de décider de rendre l’accès de ces étudiants plus facile aux cellules d’écoute et d’accompagnement psychopédagogique.
Contributeur Unique A La Théorie Politiques, Aux Et A La Pratique : Ceci par les moyens de la sensibilisation permanente et médiatisée sur l’importance de rencontrer régulièrement un conseiller d’orientation et/ou un psychologue scolaire. Et aussi la nécessité d’impliquer les familles afin d’influencer les cognitions sociales qui entourent l’échec scolaire et par la même occasion de réduire la déperdition scolaire.
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Aggoun, Samir. "Complementary investigations in a histology-embryology lab." Batna Journal of Medical Sciences (BJMS) 2, no. 2 (December 30, 2012): 182–85. http://dx.doi.org/10.48087/bjmstf.2015.2218.
Анотація:
L’activité d’un laboratoire d’histologie–embryologie repose sur deux domaines qui s’occupent de l’exploration des cellules. Le premier s'intéresse aux cellules haploïdes ou spermatozoïdes : c’est la biologie de la reproduction, qui est une discipline médicale qui réunit toutes les analyses biologiques du sperme humain initiées par le spermogramme et accomplies par les explorations de la procréation médicalement assistée ; ces analyses sont réalisées dans le cadre du bilan d'infertilité masculine. Le second domaine s’occupe des cellules diploïdes : c’est la cytologie ou cytopathologie, qui s'appuie principalement sur l'observation microscopique des altérations morphologiques des cellules recueillies d’organes ou des liquides biologiques.
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Zurawski, Jeffrey V., Jonathan M. Conway, Laura L. Lee, Hunter J. Simpson, Javier A. Izquierdo, Sara Blumer-Schuette, Intawat Nookaew, Michael W. W. Adams, and Robert M. Kelly. "Comparative Analysis of Extremely Thermophilic Caldicellulosiruptor Species Reveals Common and Unique Cellular Strategies for Plant Biomass Utilization." Applied and Environmental Microbiology 81, no. 20 (August 7, 2015): 7159–70. http://dx.doi.org/10.1128/aem.01622-15.
Анотація:
ABSTRACTMicrobiological, genomic and transcriptomic analyses were used to examine three species from the bacterial genusCaldicellulosiruptorwith respect to their capacity to convert the carbohydrate content of lignocellulosic biomass at 70°C to simple sugars, acetate, lactate, CO2, and H2.Caldicellulosiruptor bescii,C. kronotskyensis, andC. saccharolyticussolubilized 38%, 36%, and 29% (by weight) of unpretreated switchgrass (Panicum virgatum) (5 g/liter), respectively, which was about half of the amount of crystalline cellulose (Avicel; 5 g/liter) that was solubilized under the same conditions. The lower yields withC. saccharolyticus, not appreciably greater than the thermal control for switchgrass, were unexpected, given that its genome encodes the same glycoside hydrolase 9 (GH9)-GH48 multidomain cellulase (CelA) found in the other two species. However, the genome ofC. saccharolyticuslacks two other cellulases with GH48 domains, which could be responsible for its lower levels of solubilization. Transcriptomes for growth of each species comparing cellulose to switchgrass showed that many carbohydrate ABC transporters and multidomain extracellular glycoside hydrolases were differentially regulated, reflecting the heterogeneity of lignocellulose. However, significant differences in transcription levels for conserved genes among the three species were noted, indicating unexpectedly diverse regulatory strategies for deconstruction for these closely related bacteria. Genes encoding the Che-type chemotaxis system and flagellum biosynthesis were upregulated inC. kronotskyensisandC. besciiduring growth on cellulose, implicating motility in substrate utilization. The results here show that capacity for plant biomass deconstruction varies acrossCaldicellulosiruptorspecies and depends in a complex way on GH genome inventory, substrate composition, and gene regulation.
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Ghalloussi, H., J. Doyen, A. Leysalle, M. Poudenx, H. Bérard, N. Venissac, and P. Bondiau. "Étude de l’efficacité à 3ans du CyberKnife® dans les carcinomes bronchiques non à petites cellules de stade I uniques ou multiples chez 289 patients." Cancer/Radiothérapie 19, no. 6-7 (October 2015): 642. http://dx.doi.org/10.1016/j.canrad.2015.07.012.
Дисертації з теми "Analyses en cellules uniques":
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Laplatine, Loïc. "Résolution spatiale en microscopie par résonance de plasmon de surface à couplage par prisme." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENY044/document.
Анотація:
La microscopie par résonance de plasmon de surface (SPR) à couplage par prisme a vu le jour à la fin des années 60. Le principal avantage de cette technique d'imagerie optique réside dans sa très grande sensibilité à de faibles variations d'indice optique ou d'épaisseurs à la surface d'un métal. De ce fait, le suivi d'interactions biologiques peut se faire en temps réel sans avoir recours à l'utilisation de marqueurs fluorescents ou enzymatiques. Depuis plus de 30 ans, la microscopie SPR s'est imposée comme la technique de référence de biodétection sans marquage. Ses champs d'application vont de la détermination de constantes d'affinité à la détection de bactéries pathogènes, en passant par la biologie cellulaire. Jusqu'à présent, on pensait la résolution spatiale limitée par la longueur de propagation des plasmons de surface. Or, de nombreux exemples ne corroborent pas cette hypothèse. Dans cette thèse, nous montrons qu'à ce phénomène de propagation se rajoute des aberrations optiques induites par l'utilisation d'un prisme pour coupler la lumière et les plasmons de surface. Nous expliquons ainsi pourquoi les résolutions expérimentales étaient souvent bien moins bonnes que celles attendues. Par l'analyse de la formation des images et la quantification des aberrations, nous aboutissons à deux nouvelles configurations optiques optimisées pour la résolution. Nous analysons ensuite quel métal offre le meilleur compromis entre longueur de propagation et sensibilité. Expérimentalement, nous obtenons une résolution comprise entre 1,5 et 4 μm suivant la direction, sur des champs de vision de plusieurs mm2, et ce, avec une sensibilité standard en biodétection. Nous sommes ainsi en mesure d'observer simultanément plusieurs milliers de cellules individuelles, eucaryotes et procaryotes. Finalement, nous développons un prototype dédié au suivi en temps réel de sécrétions de protéines par des cellules immunitaires. Les limites de la microscopie SPR et les solutions qui permettraient de faire aboutir ce type d'étude sont examinées. Des études préliminaires sont aussi menées sur l'amélioration de la détection de bactériesPrism-based surface plasmon resonance (SPR) microscopy is an optical imaging technique invented in the late 60s'. Its main advantage lies in its high sensitivity to optical index or thickness variations at a metal surface. Therefore, the monitoring of biological reactions can be performed in real-time without labeling agent such as fluorescence or enzymes. Over the last 30 years, SPR microscopy has become the major technique in label-free biodetection. The field of application range from the determination of affinity constant in biochemistry to the detection of pathogenic bacteria via cellular biology. Until now, the propagation length of the surface plasmons has been considered as the spatial resolution limit. However, many examples do not support this statement. In this PhD thesis, we demonstrate that the resolution is also limited by optical aberrations induced by the prism used to couple light and surface plasmons. Thus, we are able to explain why the experimental resolution was usually worse than the predicted one. The analysis of the image formation and the quantification of aberrations lead us to suggest two new optical configurations optimized for resolution. We also analyze which metal exhibits the better trade-off between propagation length and sensitivity. Experimentally, we obtain a resolution between 1.5 and 4 μm depending on the direction, on field-of-view up to several mm2, and with a standard sensitivity for biodetection (monolayer of DNA). We are then able to observe simultaneously several thousands of individual eukaryote and prokaryote cells. Finally, we develop a prototype dedicated to the real-time monitoring of protein secretion by immune cells. The limits of SPR microscopy and the solutions which could allow this kind of study are discussed. Preliminary results on the improvement of bacterial detection are also presented
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Deprez, Marie. "Étude de l’hétérogénéité cellulaire et des dynamiques de régénération de l’épithélium respiratoire sain par analyses des signatures transcriptionnelles sur cellules uniques." Electronic Thesis or Diss., Université Côte d'Azur (ComUE), 2019. http://www.theses.fr/2019AZUR6022.
Анотація:
Les progrès technologiques en séquençage haut débit et en manipulation cellulaire permettent d'analyser simultanément et indépendamment le contenu de nombreuses cellules (ARN, ADN,...). Cette révolution "omique" offre un nouveau cadre pour revisiter la "Théorie Cellulaire", essentiellement basée sur des caractéristiques morphologiques et fonctionnelles. Les nombreuses modalités cellulaires désormais accessibles au niveau de la cellule unique, telles que leur transcriptome, leur localisation spatiale, leurs trajectoires développementales, enrichissent considérablement cette définition, et établissent un contexte totalement renouvelé pour réévaluer la définition de "types" ou d’"états" cellulaires ainsi que leurs interactions. \Mon travail de thèse a été de mettre en place des approches statistiques appropriées pour analyser ces données transcriptomiques sur cellule unique caractérisées par une forte variance, la présence d'un pourcentage élevé de valeurs nulles et un grand volume de données. Mon travail s’est focalisé sur le modèle expérimental central de mon laboratoire d’accueil, l'épithélium des voies respiratoires humaines. Les voies respiratoires humaines sont bordées d'un épithélium pseudo-stratifié composé principalement de cellules basales, sécrétrices, à gobelet et multiciliées. Les voies respiratoires constituent en outre un véritable écosystème cellulaire, dans lequel la couche épithéliale interagit étroitement avec les cellules immunitaires et mésenchymateuses. Cette coordination entre les cellules assure une bonne défense du système respiratoire et sa correcte régénération en cas d'agressions extérieures. Une meilleure compréhension des situations cellulaires normales et pathologiques peut améliorer les approches pour lutter contre des pathologies telles que la maladie pulmonaire obstructive chronique, l'asthme ou la mucoviscidose.J'ai d'abord pu caractériser au niveau de la cellule unique la séquence précise et spécifique des événements conduisant à la régénération fonctionnelle de l'épithélium, en utilisant un modèle 3D de cellules humaines. J'ai identifié des hiérarchies de lignées cellulaires et j'ai pu reconstruire les différentes trajectoires possibles de différentiation cellulaire. J'ai confirmé des trajectoires cellulaires décrites précédemment, mais j'ai aussi découvert une nouvelle trajectoire reliant les cellules à gobelet aux cellules multiciliées, identifiant de nouvelles populations cellulaires et de nouvelles interactions moléculaires impliquées dans le processus de régénération de l'épithélium sain des voies aériennes humaines. J'ai ensuite construit un atlas des différents types cellulaires qui tapissent les voies respiratoires humaines saines, du nez jusqu’à la 12ième génération de bronches. Le profilage de 10 volontaires sains a généré un ensemble de données de 77 969 cellules, provenant de 35 emplacements distincts, qui comprend plus de 26 types cellulaires épithéliaux, immunitaires et mésenchymateuses. Cet atlas illustre l'hétérogénéité cellulaire présente dans les voies respiratoires. Son analyse révèle une différence d'expression des gènes entre le nez et les voies respiratoires pulmonaires que j’ai caractérisé dans les cellules suprabasales, sécrétrices et multiciliées. Mes travaux ont également permis d'améliorer la caractérisation de certaines populations de cellules rares, comme les cellules "hillock", déjà décrites chez la souris. En conclusion, mon travail contribue à une meilleure compréhension des dynamiques de différenciation et d'hétérogénéité cellulaire dans les voies respiratoires humaines saines. La ressource ainsi constituée sera extrêmement utile dans tout projet futur visant à analyser avec précision les conditions spécifiques des maladies respiratoiresImprovements made in nucleic acid sequencing and cell handling technologies now offer the opportunity to analyze simultaneously the content of numerous single cells (RNA, DNA, ...) by global and unbiased approaches. This single-cell ‘omics’ revolution provides a new framework to revisit the “Cell Theory”, elaborated over several centuries, and essentially based on morphological and functional features. The many cell modalities now accessible at single- cell level, such as their transcriptome, spatial localization, developmental trajectories, enrich considerably this definition, and set a renewed context to precisely reassess the definition of ‘cell types’, ‘cell states’ as well as their different interactions and fates.My thesis work initially set up ad hoc approaches and statistical framework to analyze appropriately these single-cell data, which deeply differ from standard bulk RNA-seq. High variance, presence of a huge percentage of null values, large volume of data are among the specific characteristics of these datasets. My work was centered on the main experimental model of my host laboratory, e.g. the human airway epithelium. Human airways are lined by a pseudostratified epithelium mainly composed of basal, secretory, goblet and multiciliated cells. Airways also constitute a true cellular ecosystem, in which the epithelial layer interacts closely with immune and mesenchymal cells. This coordination between cells ensures proper defense of the respiratory system and its correct regeneration in case of external aggression and injuries. A better understanding of the operating sequences in normal and physiopathological situations is relevant in pathologies such as chronic obstructive pulmonary disease, asthma or cystic fibrosis.First, I characterized at a single cell level the precise and cell-specific sequence of events leading to functional regeneration of the epithelium, using a 3D model of human cells. I then built a single-cell atlas of the different cell types that are lining healthy human airways from the nose to the 12th generation of bronchi.By applying computational and statistical approaches, I have identified cell lineage hierarchies and was able to reconstruct a comprehensive cell trajectory roadmap in human airways. I not only confirmed previously described cell lineages, but I have also discovered a novel trajectory that links goblet cells to multiciliated cells, identifying novel cell populations and molecular interactors involved in the process of healthy human airway epithelium regeneration. The profiling of 12 healthy volunteers then generated a dataset of 77,969 cells, derived from 35 distinct locations. The resulting atlas is composed of more than 26 epithelial, immune and stromal cell types demonstrating the cellular heterogeneity present in the airways. Its analysis has revealed a strong proximo-distal gradient of expression in suprabasal, secretory, or multiciliated cells between the nose and lung airways. My work has also improved the characterization of rare cells, including “hillock” cells that have been previously described in mice.In conclusion, this work probably represents one of the first single-cell investigations in human airways. It brings original contributions to our understanding of differentiation’s dynamics and cellular heterogeneity in healthy human airways. The resulting resource will be extremely useful for any future single-cell investigators and also for establishing a very useful joint between clinical and biological works. As such, it will constitute a reference in any future project aiming to precisely analyze specific disease conditions
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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.
Анотація:
La leucémie myéloïde chronique est une hématopoïèse maligne clonale, caractérisée par l'acquisition de la translocation t (9;22) conduisant au chromosome Ph1 et à son homologue l'oncogène BCR-ABL, dans une cellule souche hématopoïétique très primitive. La LMC est un modèle de thérapies ciblées, car il a été démontré que la preuve de la faisabilité du ciblage de l'activité tyrosine kinase (TK) BCR-ABL à l'aide d'inhibiteurs de TK (TKI) entraîne des réponses et des rémissions majeures. Cependant, les problèmes actuels rencontrés dans ces thérapies sont la résistance des cellules souches leucémiques primitives et leur persistance qui serait liée à l'hétérogénéité des cellules souches au moment du diagnostic, ce qui conduit à la sélection clonale de cellules résistant aux thérapies TKI. J'ai appliqué la technologie de l'analyse du transcriptome des cellule uniques aux cellules de la LMC en utilisant un panel de gènes impliqués dans différentes voies, combinée à l'analyse d'inférence de trajectoire au modèle d'expression des gènes. Les résultats ont montré un état transitoire des cellules souches comprenant des gènes embryonnaires identifiés dans les cellules de la LMC au moment du diagnostic, ce qui pourrait contribuer à la résistance et à la persistance de la LSC. En outre, l'oncoprotéine Bcr-Abl est la tyrosine kinase constitutivement active produite par le gène chimérique BCR-ABL dans la leucémie myéloïde chronique (LMC). Les cibles transcriptionnelles de Bcr-Abl dans les cellules leucémiques n'ont pas été étudiées de manière approfondie. Une expérience de transcriptome utilisant la lignée cellulaire UT7 hématopoïétique exprimant BCR-ABL, a identifié la surexpression du facteur d'élongation eucaryote kinase 2 (eEF2K) qui joue un rôle majeur dans la survie des cellules en cas de privation de nutriments. Dans l'ensemble, les données suggèrent que la surexpression de eEF2K dans la LMC est associée à une sensibilité accrue à la privation de nutrimentsChronic 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
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Labrunie, Antoine. "Matériaux « uniques » pour cellules solaires organiques mono-composant." Thesis, Angers, 2017. http://www.theses.fr/2017ANGE0044/document.
Анотація:
Au cours des dernières années, le développement des cellules organiques à réseaux interpénétrés a permis d’améliorer les rendements de conversion photovoltaïque (PV). Ces dispositifs incorporent une couche active constituée d’un mélange d’un matériau donneur d’électron (D) et d’un matériau accepteur d’électron (A). La réalisation de ces cellules requiert une optimisation minutieuse de ce mélange et de la morphologie de cette couche photo-active qui en résulte. Cette dernière peut cependant évoluer spontanément vers une ségrégation de phase, généralement délétère pour les performances PV. Une solution possible, et relativement peu étudiée, consiste à lier chimiquement le donneur D et l’accepteur A par un espaceur non-conjugué. Les travaux décrits dans ce manuscrit portent sur la synthèse et la caractérisation d’assemblages moléculaires de type D-σ-A ainsi que leur utilisation comme matériau dit « unique » pour la fabrication de cellules solaires organiques mono composant. Une première famille de dyades et triades à base d’un bloc donneur de type quaterthiophène a été étudiée. Cette partie décrit la méthodologie générale d’assemblage des blocs D et A via une réaction de cycloaddition de type Huisgen. Au cours des chapitres suivant, plusieurs dyades basées sur un bloc donneur « push-pull » ont été synthétisées puis caractérisées. Les performances PV de ces composés ont été évaluées au sein de cellules solaires mono-composant et les meilleurs rendements de conversion, atteignant 1.4 %, rivalisent avec l’état de l’artOver the last few years, the development of bulk heterojunction organic solar cells (BHJ OSCs) led to significant increase in photovoltaic (PV) efficiency. Such devices are based on interpenetrated networks of an electron-donor material (D) and an electron-acceptor material (A) constituting the active layer. Nevertheless a careful optimization of the morphology is required to reach high power conversion efficiency. Furthermore, this optimized morphology can evolve towards spontaneous phase segregation which can be detrimental for the PV performances. To circumvent these limitations, a relatively unexplored approach relies on the use of a material where the donor and the acceptor moieties are covalently linked to each other through a nonconjugated π-connector. In this context, the work reported herein describes the synthesis and characterization of various molecular D-σ-A assemblies, as well as their preliminary evaluation as “unique” material for the realisation of single component organic solar cells (SC-OSCs). A first family of dyads and triads, based on quaterthiophene moieties as donor block, was studied. A general methodology to assemble the two D and A blocks via a Huisgen-type click-chemistry is described. Then, in the next chapters, several dyads based on a “push-pull” donor block have been synthesized and characterized. The PV performances of these compounds have been evaluated in SC-OSCs leading to power conversion efficiency up to 1.4 %, a value close to the state of the art
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Geisler, 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.
Анотація:
Dans cette thèse est présentée une nouvelle technologie microfluidique de capture de cellules uniques basée sur l’utilisation d’hydrogels thermoactivables. Nous utilisons notamment le PolyNIPAM, un polymère dont le volume est augmenté dans l'eau de 400% lorsque la température est inférieure à 32°C et est dégonflé lorsque la température est supérieure à 34°C. Nous exploitons ce gonflement réversible pour ouvrir et fermer des compartiments intégrés dans une chambre microfluidique.Le greffage et la structuration de ces motifs d’hydrogel repose sur la chimie click thiol-ène, initiée par voie thermique ou par irradiation UV. Nous avons développé des méthodes et procédés de microfabrication dans le but de diversifier les substrats d’accroche (du verre vers le PDMS, COC, PMMA, etc), d’élargir la gamme des épaisseurs des structures réalisables (de quelques microns vers la dizaine de microns d’épaisseur) et de renforcer nos connaissances concernant l'incidence de la fabrication sur le comportement de l’hydrogel. Un protocole de photolithographie robuste est finalement obtenu permettant le design de toute sorte de motif 2D sur différents choix de substrat. Une application possible détaillée par la suite est le développement de ces puces microfluidiques capables de capturer des cellules uniques dans des compartiments en hydrogel. (confidentiel)We 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)
6
Vianay, Benoit. "Adhérence de cellules uniques sur supports micro-structurés." Phd thesis, Grenoble 1, 2009. http://www.theses.fr/2009GRE10329.
Анотація:
L'adhérence cellulaire est un processus vital impliqué dans de nombreux phénomènes biologiques fondamentaux comme la diérenciation, la réparation tissulaire ou encore le développement cellulaire. Cette thèse porte sur une étude alliant expériences et modélisation de cellules uniques en adhérence sur des supports micro-structurés Les résultats montrent que la contrainte géomé- trique imposée par les supports à contraste adhésif limite l'adhérence. Au-delà de cette limitation, une organisation reproductible du cytosquelette d'actine est observée cela suggère l'existence de lois physiques simples régissant ce processus. Nous avons développé une méthode de classication des formes géométriques élémentaires observées expérimentalement nous permettant d'obtenir des statistiques robustes. En nous basant sur le modèle de Potts Cellulaire, nous avons pu reproduire les résultats expérimentaux. Ce modèle énergétique démontre que les formes élémentaires sont des états métastables utilisés par les cellules au cours de l'adhérence. Les paramètres du modèle sont reliés aux paramètres biologiques pertinents. Nous présentons des résultats qui relient la courbure des interfaces aux paramètres biologiques. Nous montrons que la mesure expérimentale de cette courbure est une représentation de la compétition entre la contractilité des bres de stress et l'élasticité du gel d'actine. Une correspondance entre les propriétés physiques issues du modèle et les processus biochimiques régulant et organisant l'adhérence cellulaire est ainsi possibleThe cell adhesion is a critical process involved in many fundamental biological phenomena as dierentiation, tissue repair or cell development. This thesis focuses on a study combining experiments and modelization of single cells spreading on micro-fabricated substrates. Experimental results show that the geometrical constraint imposed by the adhesiveness contrast limits the adhesion. Beyond this limitation, a reproducible organization of the actin cytoskeleton of cells spreading on micro-structured materials suggests that simple physical laws govern the process. We have developed a classication method of basic geometrical shapes observed experimentally to obtain robust statistics. Based on the Cellular Potts model, we reproduced experimental results. This energetical model shows that the basic shapes are metastable states used by cells during spreading. The model parameters are linked to relevant biological parameters. We present results that connect the curvature of interfaces to biological parameters. We show that the experimental measurement of this curvature represents the competition between the contractility of stress bers and the elasticity of the actin gel. A correspondence between the physical properties in the model and the biochemical processes that regulate and organize the cellular adhesion is possible
7
Vianay, Benoit. "Adhérence de cellules uniques sur supports micro-structurés." Phd thesis, Grenoble 1, 2009. http://tel.archives-ouvertes.fr/tel-00455350.
Анотація:
L'adhérence cellulaire est un processus vital impliqué dans de nombreux phénomènes biologiques fondamentaux comme la diérenciation, la réparation tissulaire ou encore le développement cellulaire. Cette thèse porte sur une étude alliant expériences et modélisation de cellules uniques en adhérence sur des supports micro-structurés Les résultats montrent que la contrainte géomé- trique imposée par les supports à contraste adhésif limite l'adhérence. Au-delà de cette limitation, une organisation reproductible du cytosquelette d'actine est observée cela suggère l'existence de lois physiques simples régissant ce processus. Nous avons développé une méthode de classication des formes géométriques élémentaires observées expérimentalement nous permettant d'obtenir des statistiques robustes. En nous basant sur le modèle de Potts Cellulaire, nous avons pu reproduire les résultats expérimentaux. Ce modèle énergétique démontre que les formes élémentaires sont des états métastables utilisés par les cellules au cours de l'adhérence. Les paramètres du modèle sont reliés aux paramètres biologiques pertinents. Nous présentons des résultats qui relient la courbure des interfaces aux paramètres biologiques. Nous montrons que la mesure expérimentale de cette courbure est une représentation de la compétition entre la contractilité des bres de stress et l'élasticité du gel d'actine. Une correspondance entre les propriétés physiques issues du modèle et les processus biochimiques régulant et organisant l'adhérence cellulaire est ainsi possible.
8
Lu, Cong. "Analyse microélectrochimique du stress oxydant à l'échelle de la cellule unique : application aux cellules cancéreuses du sein." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00828217.
Анотація:
Les quantités et flux infinitésimaux de biomolécules électroactives émises par une cellule unique isolée en boite de Pétri peuvent être mesurés en temps réel par une ultramicroélectrode placée au contact de la cellule sécrétrice. Le travail présenté dans ce manuscrit a pour but d'étendre cette méthodologie analytique d'utilisation des microélectrodes de carbone platiné à l'étude du lien entre stress oxydant et l'effet de substances anti-cancéreuses (FcdiOH, DP1 et Fc-OH-TAM) sur des cellules tumorales du sein. Le signal ampérométrique est collecté par une microélectrode de carbone platiné positionnée à une centaine de nanomètres au-dessus d'une cellule tumorale du sein et incubée en présence d'espèces anticancéreuses de type ferrocifènes. La libération in situ des espèces réactives de l'oxygène (ROS) et de l'azote (RNS), i.e., H2O2, ONOO-, NO et NO2-, par ces cellules (MCF7 et MDA-MB-231) est analysée. Les études morphologiques montrent que les produits FcdiOH, DP1 et Fc-OH-TAM présentent un effet anti-prolifératif significatif. Le traitement avec Fc-diOH et surtout DP1 augmente significativement la production de ROS. Par contre, Fc (témoin) et Fc-OH-TAM n'ont pas ou très peu d'effet. Cela est assez surprenant pour Fc-OH-TAM, qui a l'effet anti-prolifératif le plus fort parmi les ferrocifènes testés. Fc-diOH et DP1, quant à eux, semblent induire une surproduction de NO° et/ou de NO2-, ainsi que du peroxyde d'hydrogène. Cette comparaison inédite entre études morphologiques et électrochimiques tend à montrer que les ferrocifènes agissent par deux voies qui sont complémentaires, soit via la formation de quinone méthide (Fc-OH-TAM), soit par réaction directe (DP1, Fc-diOH).
9
Woringer, Maxime. "Tools to analyze single-particle tracking data in mammalian cells." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS419.
Анотація:
Ce travail présente des outils pour analyser la régulation de la transcription dans les cellules eucaryotes, en particulier pour le suivi de facteurs de transcription (TF) individuels dans les cellules de mammifères. Un noyau de cellule eucaryote est complexe et contient de nombreuses molécules (ADN, ARN, protéines, ATP, etc). Ces molécules interagissent avec des TF et influencent la transcription. Certaines de ces interactions peuvent être étudiées par des techniques de biochimie. La plupart, en particulier les interactions faibles, non covalentes, sont invisibles par ces méthodes. La microscopie de cellules vivantes et le suivi de molécules uniques (SPT en anglais) sont de plus en plus utilisées pour étudier ces phénomènes. L'inférence des paramètres biophysiques d'un facteur de transcription, par exemple son coefficient de diffusion, son nombre de sous-populations ou son temps de résidence sur l'ADN sont cruciaux pour comprendre sa dynamique et son influence sur la transcription. Des outils validés et précis sont donc nécessaires pour analyser les données de SPT. Pour être utile, un outil de SPT doit être non seulement validé, mais aussi accessible à des non-programmeurs. Ils doivent aussi tenir compte des biais expérimentaux présents dans les données. Nous proposons un outil d'analyse de SPT, qui se fonde sur l'estimation du propagateur de la diffusion. Ce outil a été validé et est accessible par une interface web. Nous avons montré qu'il donne des résultats proches de l'état de l'art. Il a été testé dans deux cadres : (1) l'étude de la diffusion augmentée par la catalyse enzymatique in vitro et (2) l'analyse de la dynamique du TF c-Myc dans des cellules de mammifèresThis 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
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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.
Анотація:
Les technologies d'analyse à l'échelle de la cellule unique ont vu le jour il y a quelques années et sont depuis en constante évolution. Ces technologies permettent de mieux comprendre le fonctionnement d'ensemble de cellules très hétérogènes. Elles permettent par exemple de découvrir et suivre des sous types cellulaires, avec des applications en cancérologie ou encore en neurobiologie. Nous avons développé une technologie pour étudier le profil d'expression de gènes d'intérêt au niveau d'une cellule unique, en utilisant la microfluidique en gouttes. En limitant le nombre de gènes étudiés comparé aux technologies commerciales de transcriptome entier, l’approche ciblée a plusieurs avantages potentiels : gagner en profondeur de séquençage, augmenter le nombre de cellules étudiées, optimiser la détection pour les bas niveaux d’expression, tout en réduisant la complexité des données et des coûts. Le ciblage est parfois indispensable, notamment lorsque les ARNs ne portent pas de séquence d’amorce générique, comme dans le cas des ARNs viraux. Deux applications sont présentées : l'analyse de l'inflammation des cellules immunitaires du cerveau aux premières étapes du développement, ainsi que l'étude de la recombinaison génétique chez le virusSingle 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
Книги з теми "Analyses en cellules uniques":
1
Kochanek, Patrick M., and Rachel P. Berger. Brain injury biomarkers in the critically ill. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0300.
Анотація:
A variety of biomarkers of brain injury are being developed in neurocritical care to study secondary injury pathways or aid in diagnostic, prognostic, and/or theragnostic applications. This chapter focuses largely on brain injury biomarkers that can be detected in serum or cerebrospinal fluid samples from patients with acute critical brain injury of various causes. Much of the work has been carried using biomarkers of proteins that are relatively unique to the brain, and that reflect damage to important cellular constituents such as neurons, astroycytes, or axons. Novel approaches that employ a panel of markers or novel analytic methods such as trajectory analysis may optimize the utility of these biomarkers in clinical practice. We anticipate that there will soon be one or more protein biomarkers of brain injury available for clinical use.
2
Sklar, Larry A., ed. Flow Cytometry for Biotechnology. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780195183146.001.0001.
Анотація:
Flow cytometry is a sensitive and quantitative platform for the measurement of particle fluorescence. In flow cytometry, the particles in a sample flow in single file through a focused laser beam at rates of hundreds to thousands of particles per second. During the time each particle is in the laser beam, on the order of ten microseconds, one or more fluorescent dyes associated with that particle are excited. The fluorescence emitted from each particle is collected through a microscope objective, spectrally filtered, and detected with photomultiplier tubes. Flow cytometry is uniquely capable of the precise and quantitative molecular analysis of genomic sequence information, interactions between purified biomolecules and cellular function. Combined with automated sample handling for increased sample throughput, these features make flow cytometry a versatile platform with applications at many stages of drug discovery. Traditionally, the particles studied are cells, especially blood cells; flow cytometry is used extensively in immunology. This volume shows how flow cytometry is integrated into modern biotechnology, dealing with issues of throughput, content, sensitivity, and high throughput informatics with applications in genomics, proteomics and protein-protein interactions, drug discovery, vaccine development, plant and reproductive biology, pharmacology and toxicology, cell-cell interactions and protein engineering.
3
Charney, Dennis S., Eric J. Nestler, Pamela Sklar, and Joseph D. Buxbaum, eds. Charney & Nestler's Neurobiology of Mental Illness. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190681425.001.0001.
Анотація:
In the years following publication of the DSM-5, the field of psychiatry has seen vigorous debate between the DSM’s more traditional, diagnosis-oriented approach and the NIMH’s more biological, dimension-based RDoC approach. Charney & Nestler’s Neurobiology of Mental Illness is an authoritative foundation for translating information from the laboratory to clinical treatment, and this edition extends beyond its reference function to acknowledge and examine the controversies and thoughts on the future of psychiatric diagnosis. In this wider context, this book provides information from numerous levels of analysis including molecular biology and genetics, cellular physiology, neuroanatomy, neuropharmacology, epidemiology, and behavior. Section I, which reviews the methods used to examine the biological basis of mental illness in animal and cell models and in humans, has been expanded to reflect important technical advances in complex genetics, epigenetics, stem cell biology, optogenetics, neural circuit functioning, cognitive neuroscience, and brain imaging. These established and emerging methodologies offer groundbreaking advances in our ability to study the brain and breakthroughs in our therapeutic toolkit. Sections II through VII cover the neurobiology and genetics of major psychiatric disorders: psychoses, mood disorders, anxiety disorders, substance use disorders, dementias, and disorders of childhood onset. Also covered within these sections is a summary of current therapeutic approaches for these illnesses as well as the ways in which research advances are now guiding the search for new treatments. The last section, Section VIII, focuses on diagnostic schemes for mental illness. This includes an overview of the unique challenges that remain in diagnosing these disorders given our still limited knowledge of disease etiology and pathophysiology. The section then provides reviews of DSM-5 and RDoC. Also included are chapters on future efforts toward precision and computational psychiatry, which promise to someday align diagnosis with underlying biological abnormalities.
Частини книг з теми "Analyses en cellules uniques":
1
Cinquin, Bertrand, Joyce Y. Kao, and Mark L. Siegal. "i.2.i. with the (Fruit) Fly: Quantifying Position Effect Variegation in Drosophila Melanogaster." In Bioimage Data Analysis Workflows ‒ Advanced Components and Methods, 147–74. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-76394-7_7.
Анотація:
AbstractMany of the methods developed for the analysis of bioimages focus on microscopy images on the cellular level. However, bioimages can also be used by biologists to assess non-cellular level morphological phenotypes. Collecting non-cellular images and developing image workflows for them is similar to working with microscopic images, but also has its unique challenges.
2
Bradbury, Joshua J., Holly E. Lovegrove, Marta Giralt-Pujol, and Shane P. Herbert. "Analysis of mRNA Subcellular Distribution in Collective Cell Migration." In Cell Migration in Three Dimensions, 389–407. New York, NY: Springer US, 2023. http://dx.doi.org/10.1007/978-1-0716-2887-4_22.
Анотація:
AbstractThe movement of groups of cells by collective cell migration requires division of labor between group members. Therefore, distinct cell identities, unique cell behaviors, and specific cellular roles are acquired by cells undergoing collective movement. A key driving force behind the acquisition of discrete cell states is the precise control of where, when, and how genes are expressed, both at the subcellular and supracellular level. Unraveling the mechanisms underpinning the spatiotemporal control of gene expression in collective cell migration requires not only suitable experimental models but also high-resolution imaging of messenger RNA and protein localization during this process. In recent times, the highly stereotyped growth of new blood vessels by sprouting angiogenesis has become a paradigm for understanding collective cell migration, and consequently this has led to the development of numerous user-friendly in vitro models of angiogenesis. In parallel, single-molecule fluorescent in situ hybridization (smFISH) has come to the fore as a powerful technique that allows quantification of both RNA number and RNA spatial distribution in cells and tissues. Moreover, smFISH can be combined with immunofluorescence to understand the precise interrelationship between RNA and protein distribution. Here, we describe methods for use of smFISH and immunofluorescence microscopy in in vitro angiogenesis models to enable the investigation of RNA and protein expression and localization during endothelial collective cell migration.
3
Ehsani, Sepehr. "New Horizons in Studying the Cellular Mechanisms of Alzheimer’s Disease." In Future of Business and Finance, 51–88. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-99838-7_4.
Анотація:
AbstractFollowing an analysis of the state of investigations and clinical outcomes in the Alzheimer’s research field, I argue that the widely accepted ‘amyloid cascade’ mechanistic explanation of Alzheimer’s disease appears to be fundamentally incomplete. In this context, I propose that a framework termed ‘principled mechanism’ (PM) can help remedy this problem. First, using a series of five ‘tests’, PM systematically compares different components of a given mechanistic explanation against a paradigmatic set of criteria and hints at various ways of making the mechanistic explanation more ‘complete’. I will demonstrate these steps using the amyloid explanation, highlighting its missing or problematic mechanistic elements. Second, PM makes an appeal for the discovery and application of ‘biological principles’ that approximate ceteris paribus generalisations or laws and are operative at the level of a biological cell. Although thermodynamic, evolutionary, ecological and other laws or principles from chemistry and the broader life sciences could inform them, biological principles should be considered ontologically unique. These principles could augment different facets of the mechanistic explanation but also allow further independent nomological explanation of the phenomenon. Whilst this overall strategy can be complementary to certain ‘new mechanist’ approaches, an important distinction of the PM framework is its equal attention to the explanatory utility of biological principles. Lastly, I detail two hypothetical biological principles and show how they could each inform and improve the potentially incomplete mechanistic aspects of the amyloid explanation and how they could provide independent explanations for the cellular features associated with Alzheimer’s disease.
4
BONNAFFOUX, Arnaud. "Inférence de réseaux de régulation de gènes à partir de données dynamiques multi-échelles." In Approches symboliques de la modélisation et de l’analyse des systèmes biologiques, 7–50. ISTE Group, 2022. http://dx.doi.org/10.51926/iste.9029.ch1.
Анотація:
L’inférence des réseaux de régulation de gènes reste un challenge majeur en biologie des systèmes malgré de nombreux efforts. Aujourd’hui, grâce aux données multi-omiques en cellules uniques, aux modèles dynamiques et stochastiques de la régulation génétique, et à la puissance de calcul disponible, de nouvelles approches telles que WASABI permettront de surmonter toutes les difficultés de ce défi.
5
Chikhale, Pratibha U., and Prashant D. Netankar. "CELLULOSE BASED NANOMATERIALS AND THEIR POTENTIAL APPLICATIONS." In Futuristic Trends in Chemical Material Sciences & Nano Technology Volume 3 Book 18, 159–75. Iterative International Publishers, Selfypage Developers Pvt Ltd, 2024. http://dx.doi.org/10.58532/v3bdcs18ch14.
Анотація:
Cellulose-based nanomaterials have gained significant attention in recent years due to their unique properties and potential applications in various fields. This chapter presents a comprehensive study of cellulose-based nanomaterials, focusing on their synthesis, characterization, and potential applications. The synthesis methods of cellulose-based nanomaterials, including nanocrystals and nanofibrils, are discussed. The production and characterization techniques, including microscopy, spectroscopy, and thermal analysis, are described to elucidate cellulose-based nanomaterials' morphological, structural, and thermal properties. Furthermore, the potential applications of cellulose-based nanomaterials in different fields are discussed. The unique properties of cellulose nanomaterials, such as high aspect ratio, biocompatibility, renewability, and mechanical strength, make them suitable candidates for applications in areas such as nanocomposites, biomedical engineering, packaging materials, energy storage devices, and environmental remediation. The chapter highlights recent advancements in these areas and explores the challenges and opportunities associated with the utilization of cellulose-based nanomaterials. In conclusion, the study of cellulose-based nanomaterials offers promising opportunities for the development of sustainable and innovative materials with diverse applications. Further research and development in this field are essential to unlock the full potential of cellulose-based nanomaterials and to address the challenges in their synthesis, processing, and integration into practical applications.
6
Kulkarni, Sunil Jayant, Gaurav Bhatikare, and Akash Shinde. "Rice Husk and Waste Paper as Feedstocks for Synthesis of Microcrystalline Cellulose." In Advances in Civil and Industrial Engineering, 160–68. IGI Global, 2023. http://dx.doi.org/10.4018/979-8-3693-0044-2.ch009.
Анотація:
Microcrystalline cellulose is a valuable material with applications in pharmaceutical, medical and food industries. Its crystalline nature and physical properties make it a unique material used as an anti-caking agent, an emulsifier, an extender, a bulking agent texturizer and a fat substitute. Microcrystalline cellulose can be synthesized from various cellulose materials. In current investigation, rice husk and waste papers are used as feedstocks for synthesis of microcrystalline cellulose. Hydrolysis, pulping, bleaching and drying are steps in MCC synthesis with deinking as additional step for waste papers. The products were analysed by FTIR method and results were compared with reference for interpretation. Rice husk and waste papers were found to have excellent potential as microcrystalline cellulose feedstock.
7
Manjula, Dr R., and Dr J. Daisy Rani. "CRYSTALLINE CELLULOSE AS BIONANOCOMPOSITE FIBER FOR ANTIMICROBIAL PACKAGING APPLICATION." In Futuristic Trends in Chemical Material Sciences & Nano Technology Volume 3 Book 11, 163–70. Iterative International Publishers, Selfypage Developers Pvt Ltd, 2024. http://dx.doi.org/10.58532/v3becs11p2ch4.
Анотація:
Over the decades in the medicinal field, biopolymers derived from natural resources have found tremendous applications in various fields such as medical, pharmaceutical, food packaging applications owing to their unique characteristics. Significantly, cellulose reinforced polymeric matrix containing smaller size fibers exhibits enhanced physical, mechanical and biological properties in contrast to the pristine polymeric matrix having greater pore size fibers. In this present study, cellulose was extracted from the crop residue of rice husk waste using a feasible chemical treatment. The surface morphological investigation and the particle size of the product cellulose were determined. Fourier transform infrared (FT-IR) spectra of the cellulose revealed that the non-cellulosic constituents from the product have removed effectively. X-ray diffraction (XRD) analysis revealed the three main diffraction peaks at 2 values of 17.8o, 22.7o, and 34.4o relative to the cellulose crystalline structure and the crystallinity index of the product cellulose was calculated to be 70 ±3 %. Thermo gravimetric analysis (TGA) showed that the crystalline cellulose decomposed at 333oC with no additional peaks indicating the purity of the extracted product. These results showed that the extracted cellulose possessed significant thermal stability and higher yield which could be used for advanced biocomposite nanofiber which could be utilised in the packaging applications.
8
Abedien, Zain Ul. "Restriction Enzymes." In Fundamentals of Cellular and Molecular Biology, 62–70. BENTHAM SCIENCE PUBLISHERS, 2024. http://dx.doi.org/10.2174/9789815238037124010007.
Анотація:
Restriction enzymes are bacterial enzymes that cleave DNA at specific recognition sequences, usually consisting of four to eight base pairs. These enzymes have become invaluable tools in molecular biology, enabling scientists to manipulate and analyze DNA in various ways. Restriction enzymes are used in various applications, including gene cloning, DNA fingerprinting, and genome mapping. By cleaving DNA at specific sites, restriction enzymes can generate DNA fragments with defined ends, which can then be ligated into vectors for cloning or PCR amplification. Using restriction enzymes in conjunction with gel electrophoresis allows for the separation and analysis of DNA fragments based on their size. There are over 3,000 known restriction enzymes, each with its unique recognition sequence. Many of these enzymes have been isolated from bacteria and are named after the bacterial species from which they were derived. Some restriction enzymes have also been engineered to recognize new recognition sequences, expanding their usefulness in molecular biology. The discovery and development of restriction enzymes have revolutionized molecular biology, allowing scientists to manipulate and analyze DNA in previously impossible ways. As our understanding of the molecular mechanisms of these enzymes continues to grow, they will likely play a critical role in genetics and biotechnology.
9
Weiss, Ron, and Thomas F. ,Jr ,. Knight. "Genetic Process Engineering." In Cellular Computing. Oxford University Press, 2004. http://dx.doi.org/10.1093/oso/9780195155396.003.0008.
Анотація:
In this chapter we present an engineering discipline to obtain complex, predictable, and reliable cell behaviors by embedding biochemical logic circuits and programmed intercellular communications into cells. To accomplish this goal, we provide a well-characterized component library, a biocircuit design methodology, and software design tools. Using the cellular gates,we introduce genetic process engineering, a methodology for modifying the DNA encoding of existing genetic elements to achieve the desired input/output behavior for constructing reliable circuits of significant complexity.We also describe BioSpice, a prototype software tool for biocircuit design that supports both static and dynamic simulations and analysis of singlecell environments and small cell aggregates. The goal of our research is to lay the foundations of an engineering discipline for building novel living systems with well-defined purposes and behaviors using standardized, well-characterized components. Cells are miniature, energy efficient, self-reproduce, and can manufacture biochemical products. These unique characteristics make cells attractive for many novel applications that require precise programmed control over the behavior of the cells. The applications include nanoscale fabrication, embedded intelligence in materials, sensor/effector arrays, patterned biomaterial manufacturing, improved pharmaceutical synthesis, programmed therapeutics, and as a sophisticated tool for in vivo studies of genetic regulatory networks. These applications require synthesis of sophisticated and reliable cell behaviors that instruct cells to make logic decisions based on factors such as existing environmental conditions and current cell state. For example, a cell may be programmed to secrete particular timed sequences of biochemicals depending on the type of messages sent by its neighbors. The approach proposed here for engineering the requisite precision control is to embed internal computation and programmed intercellular communications into the cells. The challenge is to provide robust computation and communications using a substrate where reliability and reproducible results are difficult to achieve. Biological organisms as an engineering substrate are currently difficult to modify and control because of the poor understanding of their complexity. Genetic modifications to cells often result in unpredictable and unreliable behavior. A single Escherichia coli bacterial cell contains approximately 1010 active molecules, about 107 of which are protein molecules.
10
Dilshad, Erum, Amna Naheed Khan, Iqra Bashir, Muhammad Maaz, Maria Shabbir, and Marriam Bakhtiar. "Single Cell Omics." In Omics Technologies for Clinical Diagnosis and Gene Therapy: Medical Applications in Human Genetics, 156–73. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815079517122010013.
Анотація:
Recent advances are nowadays providing opportunities to examine the complexities of organs and organisms at the single-cell level. The conventional cell.based analysis mainly examines the cellular processes from the bulk of cells but single.cell omics provides a more detailed insight into individual cell phenotypes, thus giving a link between the phenotype and genotype of cells. Single-cell analysis can be performed at genome, epigenome, transcriptome, proteome and metabolome levels and thus makes it possible to come across mechanisms not seen during the sequencing of bulk tissues. Researchers need to isolate single cells before the initiation of single-cell analysis. For this, various strategies like FACS, MACS, LCM, micro-manipulation and micro-fluids are used for cell isolation depending upon their physical properties and cellular biological characteristics. The analysis of single-cell data at multiple levels gives us an unusual view of multilevel transformation at the single-cell level and thus providing a better chance to discover novel biological processes. High throughput analysis of single cells at genome, transcriptome and proteome levels provides unique and important insights into cell variability and diverse processes like development, genetic expressions and severity of different symptoms in disease pathogenesis.
Тези доповідей конференцій з теми "Analyses en cellules uniques":
1
Steinkamp, John A. "Phase-Sensitive Flow Cytometry: New Technology For Analyzing Biochemical, Functional, and Structural Features in Fluorochrome-Labeled Cells/Particles." In Laser Applications to Chemical Analysis. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/laca.1994.thc.2.
Анотація:
Flow cytometry (FCM) instruments rapidly measure biochemical, functional, and cytological properties of individual cells and macromolecular components, e.g., chromosomes, for clinical diagnostic medicine and biomedical and environmental research applications. These measurements are based on labeling cells with multiple fluorochromes for correlated analysis of macromolecules, such as, DNA, RNA, protein, and cell-surface receptors. In addition to utilizing the spectral emission properties of fluorescent markers, i.e., different colors/intensities, to measure specific cellular features, the excited state lifetimes also can provide a means to discriminate among the different fluorochromes. A new FCM approach, based on phase-resolved fluorescence lifetime spectroscopy methods (Vesoelova et al, 1970, Lakowicz and Cherek, 1981), recently has been developed to provide unique capabilities for separating signals from multiple overlapping emissions in fluorochrome-labeled cells as they pass across a modulated laser excitation source (Steinkamp and Crissman, 1993). In addition, the measurement of fluorescence lifetime (Pinsky et al, 1993, Steinkamp et al, 1993) also is of importance because it provides information about fluorophore/cell interactions. An important advantage of lifetime measurements is that lifetimes in some case can be considered as absolute quantities. However, the lifetime of fluorophores bound to cellular macromolecules can be influenced by physical and chemical factors near the binding site, such as solvent polarity, cations, pH, energy transfer, excited-state reactions, and quenching. Thus, lifetime measurements can be used to probe the cellular environment, possibly including chemical and structure changes that occur in DNA and chromatin. Table I lists the lifetimes of some typical fluorochromes that are used to quantify cellular DNA, total protein, and antibody-labeling to cellular antigens.
2
Guarino, S., and V. Tagliaferri. "Fabrication of Aluminium Foam Components by Using Powder Compact Melting Method." In ASME 7th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2004. http://dx.doi.org/10.1115/esda2004-58607.
Анотація:
Recently, closed cell cellular metals have been gaining a very high interest due to their unique characteristic applications in various technology domains. They combine the advantages of a metal with the structural advantages of foam. Among these, aluminium foams have created a great interest due to their light weight structure and their various applications in the automotive, aerospace and allied industries. Aluminium foam possesses high stiffness and low density, it has good energy-absorbing properties making it good for crash-protection and packaging and it has attractive heat-transfer properties that permit to use these materials to cool electronic equipment and as heat exchangers in engines. However, its manufacturing techniques and characterization methods need more attention. The inadequate knowledge on the physical phenomena governing the foaming process does not allow to obtain products with repeatable characteristics. In this paper aluminium foams in various fabrication components were produced by applying the powder compact melting method. In particular metal powders (AlSi7) and powdered gas-releasing blowing agents (TiH2) were mixed and subsequently pressed to obtain a foamable precursor material. The resulting precursor was then foamed by heating it up to above its melting point. Experimental tests were performed to study the fabrication of aluminum foam components and with the extent of optimize the pressing parameters of the foamable precursor material, the foaming temperature and the heating rate during foaming. It was studied the effects of geometrical discontinuities in the mould (such as holes, restrictions, etc) on the evolution and on the morphology of metal foams.
3
McClure, Michael J., Scott A. Sell, David G. Simpson, Beat H. Walpoth, and Gary L. Bowlin. "Optimizing a Three Layered Electrospun Matrix to Mimic Native Arterial Architecture: Cellular and Mechanical Analysis." In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53689.
Анотація:
The architecture of the vascular wall is highly intricate and requires unique biomechanical properties in order to function properly. Native artery is composed of a mix of collagen, elastin, endothelial cells (ECs), smooth muscle cells (SMC), fibroblasts, and proteoglycans arranged into three distinct layers: the intima, media, and adventitia. Throughout artery, collagen and elastin play an important role, providing a mechanical backbone, preventing vessel rupture, and promoting recovery while undergoing pulsatile deformations [1]. The low-strain mechanical response of artery to blood flow is dominated by the elastic behavior of elastin which prevents pulsatile energy from being dissipated as heat [2]. Previous work has shown the ability to fabricate multi-layered electrospun scaffolds composed of polycaprolactone (PCL), elastin (ELAS), and collagen (COL), and their associated mechanical advantages. PCL was chosen, in this case, to provide mechanical integrity and elasticity, while elastin and collagen would provide further elasticity and bioactivity [3,4]. However, when the grafts were implanted in the descending aorta of a rat, cellular results were not as desirable as predicted. Therefore, further graft optimization was required. The hypothesis of this study was that blended polymers and biopolymers would be conducive for cellular attachment through specific integrin binding sites. To test this hypothesis, human umbilical artery smooth muscle cells (hUASMC) were seeded on electrospun PCL, COL, and ELAS blends for evaluation in a cell adhesion inhibition experiment.
4
Tuladhar, Slesha, Scott Clark, and MD Ahasan Habib. "Controlling Rheological Properties of Hybrid Hydrogel Using Short Fiber for Extrusion-Based 3D Bioprinting Process." In ASME 2023 18th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/msec2023-104233.
Анотація:
Abstract Among various available 3D bioprinting techniques, extrusion-based three-dimensional (3D) bio-printing allows the deposition of cell-laden bio-ink, ensuring predefined scaffold architecture that may offer living tissue regeneration. With a combination of unique characteristics such as biocompatibility, less cell toxicity, and high-water content, natural hydrogels are a great candidate for bio-ink formulation for the extrusion-based 3D bioprinting process. However, due to its low mechanical integrity, hydrogel faces a common challenge in maintaining structural ty. To tackle this challenge, we characterized the rheological properties of a set of hybrid hydrogels composed of cellulose-derived nanofiber (TEMPO-mediated nano-fibrillated cellulose, TONFC), carboxymethyl cellulose (CMC) and commonly used alginate. A total of 46 compositions were prepared using higher (0.5% and 1.0%) and lower percentages (0.005% and 0.01%) of TONFC, 1%–4% of CMC, and 1%–4% of alginate to analyze the rheological properties. The shear thinning coefficients of n and K were determined for each composition from the flow diagram and co-related with the 3D printability. The ability to control rheological properties with various ratios of a nanofiber can help achieve a 3D bio-printed scaffold with defined scaffold architecture.
5
Schultz, Joshua A., and Jun Ueda. "Analysis of Antagonist Stiffness for Nested Compliant Mechanisms in Agonist-Antagonist Arrangements." In ASME 2011 Dynamic Systems and Control Conference and Bath/ASME Symposium on Fluid Power and Motion Control. ASMEDC, 2011. http://dx.doi.org/10.1115/dscc2011-5953.
Анотація:
Members of the animal kingdom produce motion by muscle contraction. Biological muscle can be viewed as a unidirectional actuator. To achieve bidirectional motion, each muscle has a corresponding antagonist muscle whose contraction produces motion in the opposite direction. This gives biological systems the unique ability to modulate the stiffness of a joint, which is important when interacting with the environment. Certain bio-inspired robotic systems incorporate antagonistic pairs in an attempt to produce similar desirable properties. The cellular actuator employs nested compliant mechanisms to produce human-scale motion from piezoelectric stack actuators, which on their own have a small displacement. The expression for the stiffness of the actuator composed of these mechanisms takes the form of a continued fraction, which results from the nested structure. In this way, the stiffness can be easily approximated to a desired degree of accuracy by considering only the outermost mechanisms.
6
Kosanović, Marta, Thomas Eichhorn, Dejan Milenković, Goran Kaluđerović, Jasmina Dimitrić Marković, and Dušan Dimić. "Synthesis, spectroscopic, and quantum-chemical analysis of mononuclear Ru(II)-naphthylhydrazine complex." In 2nd International Conference on Chemo and Bioinformatics. Institute for Information Technologies, University of Kragujevac, 2023. http://dx.doi.org/10.46793/iccbi23.391k.
Анотація:
Ruthenium(II) complexes have become increasingly recognized and utilized as potent anticancer agents in recent years. These compounds possess unique capabilities in targeting cancer cells and interfering with vital cellular processes, offering new hope in the relentless battle against cancer. This research study focuses on the characterization of a newly synthesized Ru(II)-naphthylhydrazine complex by IR and NMR spectroscopies. NMR spectral data have revealed the presence of different chemical environments within 1 based on the chemical shifts observed in the 1H and 13C NMR spectra. The infrared spectra were recorded in the region ranging from 400 cm-1 to 4000 cm-1 , capturing a comprehensive range of vibrational modes of the studied compound with the main chemical groups outlined. The quantum-chemical optimization of 1 at B3LYP/6-31+G(d,p)(H,C,N,Cl)/LanL2DZ(Ru) level of theory allowed the prediction of structural parameters and analysis of intramolecular interactions governing stability through Natural Bond Orbital approach. The future biological investigation of this compound is advised.
7
Ruder, Warren C., Erica D. Pratt, Nailah Z. Brandy, David A. LaVan, Philip R. LeDuc, and James F. Antaki. "Stretch-Activated Calcium Signal Propagation Following Mechanical Stimulation of Focal Adhesions." In ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176431.
Анотація:
Cells translate environmental mechanical stimuli into biochemical reactions that govern a range of cellular processes such as proliferation, death and tissue matrix remodeling. Mechanical activation of individual focal adhesions formed between the cell and its environment directly correspond to several internal responses. Intracellular calcium concentration, [Ca2+]in, has been shown to profoundly change during force sensing. In order to understand this dynamic in cells, we compared calcium mobilization resulting from chemical stimulation and that resulting from mechanical stimulation. We have analyzed the response of fibroblasts to membrane displacements of over 5 μm resulting in eventual spikes in [Ca2+]in. Our data initially indicates that fibroblasts may process mechanical calcium events in unique manner in comparison to other cell types. This finding has implications in a range of fields including mechanobiology and magnetics based activation.
8
Chae, Inseok, Amira Meddeb, Zoubeida Ounaies, and Seong H. Kim. "Tailoring and Characterization of the Liquid Crystalline Structure of Cellulose Nanocrystals for Opto-Electro-Mechanical Multifunctional Applications." In ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/smasis2018-8016.
Анотація:
Liquid crystalline (LC) behaviors of cellulose nanocrystal (CNC), derived from wood, cotton or other cellulose-based biopolymers, have been actively investigated due to their unique optical properties and their superb mechanical properties, which open up potential applications in bioelectronics and biomedical engineering. In particular, many attempts have been made to control phase and orientation of LC-CNCs because they are critical factors deciding optical and mechanical properties, and electromechanical performances. Through the applications of mechanical force, electric field and magnetic field, some degree of success has been achieved; however, realizing homogeneous arrangements of CNCs that can be exploited at the macroscale is still elusive, owing to a variety of intermolecular interactions. The characterizations of the LC phase and orientation of CNCs are also challenging due to their complex biological structures. In this report, we introduce approaches to control the phase and orientation of LC-CNCs through the self-assembly, mechanical force and electric field. The liquid crystalline behaviors of CNCs in polar solvents and at the air/water interface are discussed. Translational and rotational behaviors of CNCs under DC electric field are also investigated as a function of their surface charge and dipole moment. In addition, we introduce a nonlinear optical process, namely, sum frequency generation (SFG) spectroscopy, for the structural characterization of LC-CNCs. Using SFG, we can analyze not only crystal phase and structure, but also polar ordering of CNCs which plays a key role in determining their electromechanical performances. Development of cellulose-based smart materials will expand the spectrum of available functional materials that are lightweight, flexible, mechanically tough, and thermally stable at moderately high temperatures (up to 300°C).
9
Zeiza, Adam Danur, Saleh Khaled Almeshari, Abdulmohsin Saleh Mansor, and Paul Joseph Tarabbia. "Reservoir Characterization and 3D Architecture of Multi-Scale Vugular Pore Systems in Carbonate Reservoirs." In SPE Reservoir Characterisation and Simulation Conference and Exhibition. SPE, 2023. http://dx.doi.org/10.2118/212629-ms.
Анотація:
Abstract This paper outlines a novel approach to an integrated 1D to 3D characterization and geomodeling of Vugular pore systems (VPS) in carbonate reservoirs. The study focused on capturing the various scales of the VPS and how they related to the 3D architecture. An integrated approach for detecting, characterizing and modeling the multi-scale VPS has been employed by utilizing multi-disciplinary datasets, that span from 3D seismic volumes, borehole images, production data to petrographic analyses. These datasets were analyzed and corroborated in the 1D, 2D and 3D domains to validate and define the occurrence and architecture of the VPS within the reservoir. Eventually, a 3D geo-cellular model of the VPS is constructed by honoring diagenetic proxies and experiments, VPS flags, fluid flow behavior and seismic attributes geobodies. VPS are observed at nearly all scales of datasets (i.e. geoscience and reservoir engineering data). They also occur at different scales of pore size ranging from millimeters to multi-meters. Many of them are even beyond the resolution of conventional whole core and basic well logs. A complete set of static and dynamic data allows a classification of the VPS into several classes based on their size, intensity and effect on reservoir properties and flow rates. Diagenetic proxies, well-based experimental variogram analyses and seismic-based geobody extraction further confirmed their architecture and distribution within 3D space. Their ramified patterns within the proximity of structural crestal areas tie quite consistently with well and seismic data. This architecture is further supported by possible hydro-dynamic corrosive fluid behavior that potentially had longer residence time in the crestal areas during late burial diagenesis stages. A modeling-while-interpreting workflow is also configured to model the VPS in 3D interactively and confirm the VPS occurrence on a well-by-well basis. This method is applied directly to the 3D full-field model and is linked to an interpretation platform. This unique approach contributes to the reduction of ambiguity in subsurface data and analysis.
10
Aleksić, Gabriela, Tomislav Cigula, and Katarina Itrić Ivanda. "Influence of multilayered films containing cellulose nanocrystals on the properties of japanese paper." In 11th International Symposium on Graphic Engineering and Design. University of Novi Sad, Faculty of technical sciences, Department of graphic engineering and design, 2022. http://dx.doi.org/10.24867/grid-2022-p50.
Анотація:
Cultural heritage objects are precious witnesses of the past, so our mission is not only to preserve them for future generations, but also make them available or open to the public. Among most fragile historic materials are paper-based materials. They are susceptible to various forms of damage and deterioration, and their preservation presents a challenging task for conservators. In recent years, the use of advanced materials with unique properties has been growing at an increasing rate, even in the traditionally slow-changing cultural heritage sector. This study models how historic paper would be affected by application of multiple coating layers containing different quantities of cellulose nanocrystals (CNCs). In our study, a 4 % CNCs aqueous suspension was used to treat the samples. In order to form a uniform layer, bar-coating method was used, and in addition, a specific layer thickness was formed in both single and multiple passes. The prepared samples were analysed for their optical properties (colour coordinates, yellowness, opacity, gloss), physical properties (Taber stiffness, weight, thickness) and surface properties (roughness). An increase of wet film deposit thickness (single layer applications) resulted in an increase of paper thickness, grammage, gloss, opacity, yellowness, the ΔE value and Taber stiffness, while its average surface roughness decreased. Multi-layer applications have gradually decreased paper thickness, while Taber stiffness remained unchanged.
Звіти організацій з теми "Analyses en cellules uniques":
1
Delmer, Deborah, Nicholas Carpita, and Abraham Marcus. Induced Plant Cell Wall Modifications: Use of Plant Cells with Altered Walls to Study Wall Structure, Growth and Potential for Genetic Modification. United States Department of Agriculture, May 1995. http://dx.doi.org/10.32747/1995.7613021.bard.
Анотація:
Our previous work indicated that suspension-cultured plant cells show remarkable flexibility in altering cell wall structure in response either to growth on saline medium or in the presence of the cellulose synthesis inhibitor 2,-6-dichlorobenzonitrile (DCB). We have continued to analyze the structure of these modified cell walls to understand how the changes modify wall strength, porosity, and ability to expand. The major load-bearing network in the walls of DCB-adapted dicot cells that lack a substantial cellulose-xyloglucan network is comprised of Ca2+-bridged pectates; these cells also have an unusual and abundant soluble pectic fraction. By contrast, DCB-adapted barley, a graminaceous monocot achieves extra wall strength by enhanced cross-linking of its non-cellulosic polysaccharide network via phenolic residues. Our results have also shed new light on normal wall stucture: 1) the cellulose-xyloglucan network may be independent of other wall networks in dicot primary walls and accounts for about 70% of the total wall strength; 2) the pectic network in dicot walls is the primary determinant of wall porosity; 3) both wall strength and porosity in graminaceous monocot primary walls is greatly influenced by the degree of phenolic cross-linking between non-cellulosic polysaccharides; and 4) the fact that the monocot cells do not secrete excess glucuronoarabinoxylan and mixed-linked glucan in response to growth on DCB, suggests that these two non-cellulosic polymers do not normally interact with cellulose in a manner similar to xyloglucan. We also attempted to understand the factors which limit cell expansion during growth of cells in saline medium. Analyses of hydrolytic enzyme activities suggest that xyloglucan metabolism is not repressed during growth on NaCl. Unlike non-adapted cells, salt-adapted cells were found to lack pectin methyl esterase, but it is not clear how this difference could relate to alterations in wall expansibility. Salt-adaped cell walls contain reduced hyp and secrete two unique PRPP-related proteins suggesting that high NaCl inhibits the cross-linking of these proteins into the walls, a finding that might relate to their altered expansibility.
2
Eshed-Williams, Leor, and Daniel Zilberman. Genetic and cellular networks regulating cell fate at the shoot apical meristem. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7699862.bard.
Анотація:
The shoot apical meristem establishes plant architecture by continuously producing new lateral organs such as leaves, axillary meristems and flowers throughout the plant life cycle. This unique capacity is achieved by a group of self-renewing pluripotent stem cells that give rise to founder cells, which can differentiate into multiple cell and tissue types in response to environmental and developmental cues. Cell fate specification at the shoot apical meristem is programmed primarily by transcription factors acting in a complex gene regulatory network. In this project we proposed to provide significant understanding of meristem maintenance and cell fate specification by studying four transcription factors acting at the meristem. Our original aim was to identify the direct target genes of WUS, STM, KNAT6 and CNA transcription factor in a genome wide scale and the manner by which they regulate their targets. Our goal was to integrate this data into a regulatory model of cell fate specification in the SAM and to identify key genes within the model for further study. We have generated transgenic plants carrying the four TF with two different tags and preformed chromatin Immunoprecipitation (ChIP) assay to identify the TF direct target genes. Due to unforeseen obstacles we have been delayed in achieving this aim but hope to accomplish it soon. Using the GR inducible system, genetic approach and transcriptome analysis [mRNA-seq] we provided a new look at meristem activity and its regulation of morphogenesis and phyllotaxy and propose a coherent framework for the role of many factors acting in meristem development and maintenance. We provided evidence for 3 different mechanisms for the regulation of WUS expression, DNA methylation, a second receptor pathway - the ERECTA receptor and the CNA TF that negatively regulates WUS expression in its own domain, the Organizing Center. We found that once the WUS expression level surpasses a certain threshold it alters cell identity at the periphery of the inflorescence meristem from floral meristem to carpel fate [FM]. When WUS expression highly elevated in the FM, the meristem turn into indeterminate. We showed that WUS activate cytokinine, inhibit auxin response and represses the genes required for root identity fate and that gradual increase in WUCHEL activity leads to gradual meristem enlargement that affect phyllotaxis. We also propose a model in which the direction of WUS domain expansion laterally or upward affects meristem structure differently. We preformed mRNA-seq on meristems with different size and structure followed by k-means clustering and identified groups of genes that are expressed in specific domains at the meristem. We will integrate this data with the ChIP-seq of the 4 TF to add another layer to the genetic network regulating meristem activity.
3
O'Neill, Sharman, Abraham Halevy, and Amihud Borochov. Molecular Genetic Analysis of Pollination-Induced Senescence in Phalaenopsis Orchids. United States Department of Agriculture, 1991. http://dx.doi.org/10.32747/1991.7612837.bard.
Анотація:
The project investigated the molecular genetic and biochemical basis of pollination-induced senescence of Phalaenopsis flowers. This experimental system offered unique advantages in that senescence is strictly regulated by pollination, providing the basis to experimentally initiate and synchronize senescence in populations of flowers. The postpollination syndrome in the Phalaenopsis orchid system was dissected by investigating the temporal and spatial regulation of ACC synthase gene expression. In the stigma, pollen-borne auxin induces the expression of the auxin-regulated ACC synthase (PS-ACS2) gene, resulting in ACC synthesis within 1 h following pollination. Newly formed ACC is oxidized by basal constitutive ACC oxidase to ethylene, which then induces the expression of the ethylene-regulated ACC synthase(PS-ACS1) and oxidase (ACO1) genes for further autocatalytic production of ethylene. It is speculated that during the 6-h period following pollination, emasculation leads to the production or release of a sensitivity factor that sensitizes the cells of the stigma to ethylene. ACC and ethylene molecules are translocated from the stigma to the labellum and perianth where ethylene induces the expression of PS-ACS1 and ACO1 resulting in an increased production of ACC and ethylene. Organ-localized ethylene is responsible for inrolling and senescence of the labellum and perianth. The regulation of ethylene sensitivity and signal transduction events in pollinated flowers was also investigated. The increase in ethylene sensitivity appeared in both the flower column and the perianth, and was detected as early as 4 h after pollination. The increase in ethylene sensitivity following pollination was not dependent on endogenous ethylene production. Application of linoleic and linoleic acids to Phalaenopsis and Dendrobium flowers enhanced their senescence and promoted ethylene production. Several major lipoxygenase pathway products including JA-ME, traumatic acid, trans-2-hexenal and cis-3-hexenol, also enhanced flower senescence. However, lipoxygenase appears to not be directly involved in the endogenous regulation of pollination-induced Phalaenopsis and Dendrobium flower senescence. The data suggest that short-chain saturated fatty acids may be the ethylene "sensitivity factors" produced following pollination, and that their mode of action involves a decrease in the order of specific regions i the membrane lipid bilayer, consequently altering ethylene action. Examination of potential signal transduction intermediates indicate a direct involvement of GTP-binding proteins, calcium ions and protein phosphorylation in the cellular signal transduction response to ethylene following pollination. Modulations of cytosolic calcium levels allowed us to modify the flowers responsiveness to ethylene.
4
Porat, Ron, Gregory T. McCollum, Amnon Lers, and Charles L. Guy. Identification and characterization of genes involved in the acquisition of chilling tolerance in citrus fruit. United States Department of Agriculture, December 2007. http://dx.doi.org/10.32747/2007.7587727.bard.
Анотація:
Citrus, like many other tropical and subtropical fruit are sensitive to chilling temperatures. However, application of a pre-storage temperature conditioning (CD) treatment at 16°C for 7 d or of a hot water brushing (HWB) treatment at 60°C for 20 sec remarkably enhances chilling tolerance and reduces the development of chilling injuries (CI) upon storage at 5°C. In the current research, we proposed to identify and characterize grapefruit genes that are induced by CD, and may contribute to the acquisition of fruit chilling tolerance, by two different molecular approaches: cDNA array analysis and PCR cDNA subtraction. In addition, following the recent development and commercialization of the new Affymetrix Citrus Genome Array, we further performed genome-wide transcript profiling analysis following exposure to CD and chilling treatments. To conduct the cDNA array analysis, we constructed cDNA libraries from the peel tissue of CD- and HWB-treated grapefruit, and performed an EST sequencing project including sequencing of 3,456 cDNAs from each library. Based on the obtained sequence information, we chose 70 stress-responsive and chilling-related genes and spotted them on nylon membranes. Following hybridization the constructed cDNA arrays with RNA probes from control and CD-treated fruit and detailed confirmations by RT-PCR analysis, we found that six genes: lipid-transfer protein, metallothionein-like protein, catalase, GTP-binding protein, Lea5, and stress-responsive zinc finger protein, showed higher transcript levels in flavedo of conditioned than in non-conditioned fruit stored at 5 ᵒC. The transcript levels of another four genes: galactinol synthase, ACC oxidase, temperature-induced lipocalin, and chilling-inducible oxygenase, increased only in control untreated fruit but not in chilling-tolerant CD-treated fruit. By PCR cDNA subtraction analysis we identified 17 new chilling-responsive and HWB- and CD-induced genes. Overall, characterization of the expression patterns of these genes as well as of 11 more stress-related genes by RNA gel blot hybridizations revealed that the HWB treatment activated mainly the expression of stress-related genes(HSP19-I, HSP19-II, dehydrin, universal stress protein, EIN2, 1,3;4-β-D-glucanase, and SOD), whereas the CD treatment activated mainly the expression of lipid modification enzymes, including fatty acid disaturase2 (FAD2) and lipid transfer protein (LTP). Genome wide transcriptional profiling analysis using the newly developed Affymetrix Citrus GeneChip® microarray (including 30,171 citrus probe sets) revealed the identification of three different chilling-related regulons: 1,345 probe sets were significantly affected by chilling in both control and CD-treated fruits (chilling-response regulon), 509 probe sets were unique to the CD-treated fruits (chilling tolerance regulon), and 417 probe sets were unique to the chilling-sensitive control fruits (chilling stress regulon). Overall, exposure to chilling led to expression governed arrest of general cellular metabolic activity, including concretive down-regulation of cell wall, pathogen defense, photosynthesis, respiration, and protein, nucleic acid and secondary metabolism. On the other hand, chilling enhanced various adaptation processes, such as changes in the expression levels of transcripts related to membranes, lipid, sterol and carbohydrate metabolism, stress stimuli, hormone biosynthesis, and modifications in DNA binding and transcription factors.
5
Shpigel, Nahum Y., Ynte Schukken, and Ilan Rosenshine. Identification of genes involved in virulence of Escherichia coli mastitis by signature tagged mutagenesis. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7699853.bard.
Анотація:
Mastitis, an inflammatory response of the mammary tissue to invading pathogenic bacteria, is the largest health problem in the dairy industry and is responsible for multibillion dollar economic losses. E. coli are a leading cause of acute mastitis in dairy animals worldwide and certainly in Israel and North America. The species E. coli comprises a highly heterogeneous group of pathogens, some of which are commensal residents of the gut, infecting the mammary gland after contamination of the teat skin from the environment. As compared to other gut microflora, mammary pathogenic E. coli (MPEC) may have undergone evolutionary adaptations that improve their fitness for colonization of the unique and varied environmental niches found within the mammary gland. These niches include competing microbes already present or accompanying the new colonizer, soluble and cellular antimicrobials in milk, and the innate immune response elicited by mammary cells and recruited immune cells. However, to date, no specific virulence factors have been identified in E. coli isolates associated with mastitis. The original overall research objective of this application was to develop a genome-wide, transposon-tagged mutant collection of MPEC strain P4 and to use this technology to identify E. coli genes that are specifically involved in mammary virulence and pathogenicity. In the course of the project we decided to take an alternative genome-wide approach and to use whole genomes bioinformatics analysis. Using genome sequencing and analysis of six MPEC strains, our studies have shown that type VI secretion system (T6SS) gene clusters were present in all these strains. Furthermore, using unbiased screening of MPEC strains for reduced colonization, fitness and virulence in the murine mastitis model, we have identified in MPEC P4-NR a new pathogenicity island (PAI-1) encoding the core components of T6SS and its hallmark effectors Hcp, VgrG and Rhs. Next, we have shown that specific deletions of T6SS genes reduced colonization, fitness and virulence in lactating mouse mammary glands. Our long-term goal is to understand the molecular mechanisms of host-pathogen interactions in the mammary gland and to relate these mechanisms to disease processes and pathogenesis. We have been able to achieve our research objectives to identify E. coli genes that are specifically involved in mammary virulence and pathogenicity. The project elucidated a new basic concept in host pathogen interaction of MPEC, which for the best of our knowledge was never described or investigated before. This research will help us to shed new light on principles behind the infection strategy of MPEC. The new targets now enable prevalence and epidemiology studies of T6SS in field strains of MPEC which might unveil new geographic, management and ecological risk factors. These will contribute to development of new approaches to treat and prevent mastitis by MPEC and perhaps other mammary pathogens. The use of antibiotics in farm animals and specifically to treat mastitis is gradually precluded and thus new treatment and prevention strategies are needed. Effective mastitis vaccines are currently not available, structural components and effectors of T6SS might be new targets for the development of novel vaccines and therapeutics.
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Ehrlich, Marcelo, John S. Parker, and Terence S. Dermody. Development of a Plasmid-Based Reverse Genetics System for the Bluetongue and Epizootic Hemorrhagic Disease Viruses to Allow a Comparative Characterization of the Function of the NS3 Viroporin in Viral Egress. United States Department of Agriculture, September 2013. http://dx.doi.org/10.32747/2013.7699840.bard.
Анотація:
Project Title: "Development of a plasmid-based reverse genetics system for the Bluetongue and Epizootic Hemorrhagic Disease viruses to allow comparative characterization of the function of the NS3 viroporin in viral egress". Project details: No - IS-4192-09; Participants – Ehrlich M. (Tel Aviv University), Parker J.S. (Cornell University), DermodyT.S. (Vanderbilt University); Period - 2009-2013. Orbiviruses are insect-borne infectious agents of ruminants that cause diseases with considerable economical impact in Israel and the United States. The recent outbreaks of BTV in Europe and of Epizootic Hemorrhagic Disease Virus (EHDV) in Israel, underscore the need for: (i) a better comprehension of the infection process of orbiviruses, (ii) the identification of unique vs. common traits among different orbiviruses, (iii) the development of novel diagnosis and treatment techniques and approaches; all aimed at the achievement of more effective control and treatment measures. It is the context of these broad goals that the present project was carried out. To fulfill our long-term goal of identifying specific viral determinants of virulence, growth, and transmission of the orbiviruses, we proposed to: (i) develop reverse genetics systems for BTV and EHDV2-Ibaraki; and (ii) identify the molecular determinants of the NS3 nonstructural protein related to viroporin/viral egress activities. The first objective was pursued with a two-pronged approach: (i) development of a plasmid-based reverse genetics system for BTV-17, and (ii) development of an "in-vitro" transcription-based reverse genetics system for EHDV2-Ibaraki. Both approaches encountered technical problems that hampered their achievement. However, dissection of the possible causes of the failure to achieve viral spread of EHDV2-Ibaraki, following the transfection of in-vitro transcribed genomic segments of the virus, revealed a novel characteristic of EHDV2-Ibaraki infection: an uncharacteristically low fold increase in titer upon infection of different cell models. To address the function and regulation of NS3 we employed the following approaches: (i) development (together with Anima Cell Metrology) of a novel technique (based on the transfection of fluorescently-labeledtRNAs) that allows for the detection of the levels of synthesis of individual viral proteins (i.e. NS3) in single cells; (ii) development of a siRNA-mediated knockdown approach for the reduction in levels of expression of NS3 in EHDV2-Ibaraki infected cells; (iii) biochemical and microscopy-based analysis of the localization, levels and post-translational modifications of NS3 in infected cells. In addition, we identified the altered regulation and spatial compartmentalization of protein synthesis in cells infected with EHDV2-Ibaraki or the mammalian reovirus. In EHDV2-Ibaraki-infected cells such altered regulation in protein synthesis occurs in the context of a cell stress reponse that includes the induction of apoptosis, autophagy and activation of the stressrelated kinase c-Jun N-terminal Kinase (JNK). Interestingly, inhibition of such stress-related cellular processes diminishes the production of infectious virions, suggesting that EHDV usurps these responses for the benefit of efficient infection. Taken together, while the present project fell short of the generation of novel reverse genetics systems for orbiviruses, the development of novel experimental approaches and techniques, and their employment in the analysis of EHDV-infected cells, yielded novel insights in the interactions of orbiviruses with mammalian cells.