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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Cukerné hospodářství rostlin a arbuskulární mykorhizní symbióza / Plant sugar metabolism and arbuscular mycorrhizal symbiosis

Konečný, Jan January 2017 (has links)
The study of arbuscular mycorrhizal symbiosis (AMS) - the mutualist relationship between the most of land plants and evolutionary old fungal group Glomeromycota - is becoming a prestigious topic. The prevalence of and extent of physiological action of AMS on plants is very interesting for the plant biology itself, but its importance grows, notably in time of global climate change, frequent soil degradation and ascending exhaustion of mineral fertilizer reserves. Although the flows in AMS of some minerals, like of phosphorus was enlightened, carbon exchange between the symbionts is still poorly understood. In this experimental work, I utilized the boom of molecular and bioinformatic methods in the quest for completely unexplained carbon flows. The organisms used include barrel medic (Medicago truncatula), the model legume for symbiotic relationships, biotic, and abiotic stresses; Rhizophagus irregularis, the widely used fungus for such experimental studies of AMS; and Sinorhizobium meliloti, the nodulating nitrogen-fixing bacterium compatible with the barrel medic. Two variants - mycorrhizal (M+) and non-mycorrhizal (NM) plants were subjected to several levels of analysis. I have checked the variants, did the measurements of phosphorus and nitrogen contents, as well as I probed the plants with...
182

Métabolisme et transport du soufre dans les graines des espèces modèles M. truncatula et Arabidopsis : étude fonctionnelle des transporteurs de sulfate / Sulfur metabolism and transport in seeds of the model species M. truncatula and Arabidopsis : functional study of sulfate transporters

Zuber, Hélène 10 February 2010 (has links)
Le soufre est un macronutriment essentiel contribuant à l’élaboration du rendement et de la qualité des graines. Chez les espèces modèles M. truncatula et Arabidopsis, les gènes associés à la réduction du sulfate et à la biosynthèse des acides aminés soufrés sont exprimés dans l’embryon lors du remplissage de la graine, soulignant l’importance du transport de sulfate jusqu’à ce tissu. Chez M. truncatula, trois gènes codant des transporteurs de sulfate putatifs, MtSultr3;5, MtSultr2;2, et MtSultr4;1, sont fortement exprimés dans la graine. Le criblage des populations de mutants disponibles a permis d’identifier des mutants Tnt1 et EMS pour ces gènes. Cette étude a parallèlement été élargie à la caractérisation de mutants ADN-T d’Arabidopsis pour les cinq transporteurs de sulfate du groupe 3 (de la membrane plasmique) et pour SULTR4;1 (vacuolaire), dont les gènes s’expriment dans la graine en développement. Un rôle des transporteurs du groupe 3 dans les échanges de sulfate à l’intérieur de la graine a été mis en évidence. En particulier, l’analyse du protéome des graines de ces mutants a révélé un défaut d’accumulation des formes processées des protéines de réserve au sein de l’embryon (sultr3;5) et des modulations spécifiques de la composition protéique suggérant l’utilisation de sources alternatives de soufre (sultr3;4). Enfin, les résultats contrastés obtenus pour le mutant sultr4;1 suggèrent un rôle de l’efflux de sulfate des vacuoles pour le maintien de l’homéostasie redox lors du développement de la graine. / Sulfur is an essential macronutrient contributing to crop yield and seed quality. In the model species M. truncatula and Arabidopsis, genes involved in sulfate reduction and sulfur amino acid biosynthesis are expressed in the embryo during seed filling, underlying the importance of sulfate transport until this tissue. In M. truncatula, three genes encoding putative sulfate transporters, MtSultr3;5, MtSultr2;2, et MtSultr4;1, are strongly expressed in seeds. By screening mutant collections, we identified Tnt1 and EMS mutants for these genes. In parallel, this study was extended to the characterization of Arabidopsis T-DNA mutants for the five sulfate transporters belonging to group 3 (plasmalemma-located) and SULTR4;1 (vacuolar), whose genes are expressed in developing seeds. A role of the group 3 sulfate transporters in sulfate exchange between seed tissue was revealed. In particular, seed proteome analysis for these mutants revealed a reduced accumulation of storage protein processing within the embryo (sultr3;5), and specific modulations of protein composition suggesting the utilization of alternative sulfur sources (sultr3;4). Finally, contrasted results obtained for the sultr4;1 mutant suggest a role of sulfate efflux from vacuole for maintaining redox homeostasis during seed development.
183

Materialvalets miljöpåverkan på transporten : En jämförelsestudie mellan transporter till flerfamiljshus i trä och betong.

Aggerstam, Elina, Lehman, Karolina January 2017 (has links)
Under året 2015 bedömde 240 av Sveriges 290 kommuner att det existerade ett underslott på bostäder. För att kunna möta behovet krävs det att många bostäder ska byggas på en kort tid. Med de klimathot som världen står inför krävs det att produktionen är uthållig och hållbar i längden. För att nå klimatmålen måste användandet av tunga fordon minskas, logistiken måste effektiviseras och alternativa transportmedel bör undersökas. Syftet med studien var att identifiera eventuella skillnader mellan byggnadsmaterialen trä och betong i transportledet. Med den insamalade datan togs olika relations- och nyckeltal fram som sedan utgjorde basen för de två formlerna som presenteras i studien. Resultatet av de olika relationstalen indikerar på att den lastade vikten inte har stor betydelse på hur mycket CO2 som släpps ut, utan att det är antalet transporter med tung lastbil som är grundproblemet till utsläppen och miljöpåverkan. Med formlerna som presenteras i studien kan antalet transporter som krävs till ett flerfamiljshus räknas ut, men även mängden CO2 som släpps ut vid fraktandet av planelementen.
184

Contribution des co-transporteurs cation chlorure KCC2 et NKCC1, à la maturation et la modulation des réseaux locomoteurs spinaux

Stil, Aurélie 09 September 2011 (has links)
Le cerveau et la moelle épinière adultes sont câblés pour traiter l’information sensorielle et la transformer en patrons d’activité cohérents qui forment la base de la perception du monde extérieur et de la motricité. Ces connexions très précises, loin d’être complètement établies à la naissance, sont affinées par l’activité électrique. Des activités spontanées (AS) peuvent être générées en l’absence de stimulation extrinsèque au système considéré. Au niveau de la moelle épinière, les AS sont responsables des mouvements spontanés et des tremblements myocloniques observés chez tous les mammifères immatures y compris chez l’humain. Elles constituent en quelque sorte les premiers pas du réseau locomoteur, ce qui signifie d’une part, qu’elles apparaissent avant l’émergence d’une activité de type locomotrice, et d’autre part, qu’elles participent à la mise en place et au raffinement d’un réseau moteur fonctionnel. La locomotion est générée par des réseaux de neurones localisés au niveau de la moelle épinière lombaire. Ces neurones constituent le générateur de rythme locomoteur (ou CPG, pour « central pattern generator »). Contrairement aux AS, l’activité locomotrice est déclenchée par une stimulation du réseau. Le patron locomoteur de décharges rythmiques est alterné de chaque côté de la moelle spinale, et entre les racines lombaires qui innervent des muscles extenseurs et fléchisseurs. / The mature brain and spinal cord are precisely wired to process sensory information into coherent patterns of activity that form the basis of our perception and motor behaviors. This precise wiring is not fully developed at birth. The pattern of connections that emerges during prenatal development only roughly approximates the final wiring. This initially coarse pattern of connections is subsequently refined by activity-dependent mechanisms that match precisely the presynaptic neurons to their appropriate target cells. In spinal cord, spontaneous activity (SA) is responsible for spontaneous limb movements and myoclonic twitching observed in all immature mammals, including human babies. SA can be seen as the first steps of the locomotor network since its participates in the development of the locomotor system.Locomotion is produced by neural networks located in the spinal cord (Central Pattern Generators (CPGs). Activation of CPGs, evokes a fictive locomotor pattern consisting of alternation between the motor bursts on the left and right sides of the spinal cord, as well as alternation between flexor and extensor bursts on the same side. Operation of neural networks depends on the balance between excitation and inhibition. At early stages of development, neuronal assemblies are hyperexcitable mainly because of GABA and glycine, the major inhibitory neurotransmitters in adults,that are depolarizing. GABA and glycine action depends on the intracellular concentration of chloride ([Cl-]i) which is finely regulated by specific cation-chloride co-transporters, called KCC2 and NKCC1.
185

Zapojení přenašečů AtKT/HAK/KUP v příjmu K+ a Cs+ rostlinami / Involvement of AtKT/HAK/KUP high-affinity transporters in plant K+ and Cs+ uptake

Šustr, Marek January 2015 (has links)
Potassium is essential macroelement and large amount of potassium is taken up by plants, because it's the major osmotic of plant cell. Due to various potassium availability in different kinds of soil, plants have evolved transport system that can maintain sufficient K+ uptake between several orders of magnitude of potassium concentration. In Arabidopsis thaliana mechanism of K+ acquisition is well understood and it's known that AtHAK5 is mainly involved in K+ uptake in its very low concentrations. AtHAK5 belongs to KT/HAK/KUP family that consist 13 members in A. thaliana. There's known function for some members for example in auxin transport in root tip (TRH1) or in K+ efflux in stomatal closure (KUP6). In this thesis possible involvement of yet unstudied transporters KUP5, KUP7, KUP9 and KUP10 in K+ acquisition and homeostasis in A. thaliana was investigated. In vitro cultivation showed that kup9 mutant has very short lateral roots in K+ deficiency. On the other hand kup5 mutant showed significantly higher dry weight in K+ deficiency than Col-0. Kup9 phenotype was successfully replicated in subsequent cultivations and anatomy of lateral root apical meristems was investigated. Root tips of kup9 were differently organized in K+ deficiency and they showed signs of early termination of meristems. To...
186

Characterization of a synthetic leoligin derivative, with agonistic FXR and enhancing macrophage cholesterol efflux activity

Kovářová, Lenka January 2016 (has links)
Charles University, Faculty of Pharmacy in Hradec Králové, Department of Biological and Medical Sciences University of Vienna, Faculty of Life Sciences, Department of Pharmacognosy Candidate: Lenka Kovářová Supervisor: Pharmdr. Miroslav Kovařík, Ph.D. Consultant: Dr. Angela Ladurner Title of the diploma thesis: Characterization of a synthetic leoligin derivative, with agonistic FXR and enhancing macrophage cholesterol efflux activity Atherosclerosis is a pathologic multifactorial process triggering the development of cardiovascular diseases, which are the leading causes of death in the western world. The initial phase of atherosclerosis is characterized by the accumulation of lipid particles, mainly low-density lipoproteins (LDL) and macrophage-derived foam cells in large arteries, leading to the gradual thickening of the vessel wall. These progressive alterations elicit plaque formation, followed by rupture, thrombosis and finally can lead to a cardiovascular event. Reverse cholesterol transport is an important preventive mechanism, which ensures removal of excessive atherogenic lipoproteins from macrophages. This efflux is facilitated by ATP binding cassette transporters, mainly ABCA1 and ABCG1 and in part by scavenger receptor B1 (SR-B1). Several nuclear receptors, including PPARγ, LXRα and LXRβ...
187

Evaluation of the NOD-like receptor protein 3 (NLRP3) inflammasome pathway in human myelomonocytic THP1 cells

Guzova, Julia Alexandrovna 07 October 2019 (has links)
Activation of the NOD-like receptor protein 3 (NLRP3) inflammasome complex causes the processing and release of mature IL-1β, with mitochondria playing key roles in its assembly. An orally active NLRP3 inflammasome inhibitor would be a significant advance in therapy for IL-1β-driven diseases. To overcome both, the variability among primary immune cells and the limitations of genetic manipulation of differentiated human or murine macrophages, we developed a simplified, reliable and relevant cell-based model for studying the NLRP3 inflammasome using the undifferentiated human myelomonocytic cell line THP1. We established that undifferentiated THP1 cells are fully competent for activation of the NLRP3 inflammasome and production of IL-1β, without differentiation into macrophages. CP-456,773 is a potent and selective inhibitor of the NLRP3 inflammasome, and it is an analogue of glyburide, a sulfonylurea receptor (SUR) inhibitor. Despite the extensive experimental use of CP-456,773, its molecular target remains unknown. Here we tested the hypothesis that mitochondrial ABCb7 or ABCb10 could be the pharmacologic targets of CP-456,773. We optimized a viral shRNA transduction method for genetic manipulations in THP1 cells and generated ABCb7 and ABCb10 knockdown (KD) THP1 cells. We demonstrate that NLRP3 inflammasome activation and CP-456,773 pharmacology are not altered in ABCb7- or ABCb10-deficient THP1 cells. For ABCb10, we confirmed these results using CRISPR/CAS9-mediated ABCb10 knockout (KO) THP1 sub-lines. In studies of mitochondrial fitness, we found that a previously observed reduction in oxygen consumption rate (OCR) following nigericin treatment was completely blocked in NLRP3 KO cells. Our data demonstrating that CP-456,773 rescues the NLRP3-dependent nigericin-induced decline in OCR and protects undifferentiated THP1 cells from nigericin-induced pyroptosis are consistent with the possibility that the NLRP3 protein itself may be the molecular target of CP-456,773. Moreover, we showed that ABCb10 KO THP1 cells exhibit increased rates of basal ATP production and glycolysis, suggesting an important role for ABCb10 in mitochondrial metabolism. Finally, RNA-Seq analysis of ABCb7 and ABCb10 KD in undifferentiated THP1 cells indicate new functions for these proteins, including cell communication and migration, apoptosis and cell adhesion. Overall, our findings demonstrate that undifferentiated THP1 cells are an ideal system in which to study the NLRP3 inflammasome.
188

Interactions de la fumée de cigarette et ses composés avec les transporteurs membranaires dans des modèles hépatiques et non-hépatiques / Interactions of cigarette smoke and its contained components with drug transporters in hepatic and non-hepatic cell models

Sayyed, Katia 29 October 2018 (has links)
La fumée de cigarette peut endommager plusieurs organes de notre organisme, causant des maladies chroniques sévères et divers types de cancers. Elle interagit notamment avec les enzymes de métabolisme des médicaments de phase I et II, et contribue ainsi à la perturbation de la pharmacocinétique de divers médicaments chez les fumeurs. Les transporteurs membranaires sont des acteurs majeurs de l'absorption, la distribution et l'élimination de médicaments, et certains sont impliqués dans les interactions médicamenteuses. De plus, ils assurent le flux des molécules endogènes physiologiques vitales, et l'élimination de divers xénobiotiques toxiques non seulement chez les mammifères mais aussi chez les êtres unicellulaires, comme les levures. Ces transporteurs sont des cibles potentielles de la fumée de cigarette. D’où l'importance d'étudier l'interaction de la fumée de cigarette et de ses composés avec les transporteurs membranaires. Nos résultats démontrent que le condensat de fumée de cigarette (CSC) modifie l'activité fonctionnelle et/ou l'expression de plusieurs transporteurs hépatiques et rénaux in vitro dans des modèles cellulaires hépatiques et/ou non-hépatiques, notamment les OATPs (organic anion transporting polypeptide), l'OCT1 (organic cation transporter 1), la BCRP (breast cancer resistance protein) et l'OAT3 (organic anion transporter 3). Une implication remarquable du récepteur Ah (AhR) est mise en évidence dans la régulation de l'expression de certains transporteurs comme la MRP4 (multidrug resistance-associated protein), la BCRP, l'OAT2 et l'OCT1 dans des cellules HepaRG exposées au CSC. De plus, chez la levure Saccharomyces cerevisiae, le CSC inhibe l'activité d'efflux notamment des transporteurs de la rhodamine 123 et de la caféine, et induit, après trois heures, leur expression avec d'autres gènes qui sont aussi impliqués dans la résistance aux xénobiotiques comme les transporteurs de la membrane plasmique le Pdr5, le Snq2, le Pdr10, le Pdr15 et le Tpo1. Enfin, un effet inhibiteur remarquable des amines aromatiques hétérocycliques (AAH) est mis en évidence in vitro, notamment celui de Trp-P-1 et de Trp-P2 sur l'activité des transporteurs OCT1 et OCT2. De plus, les données in silico suggèrent que des descripteurs moléculaires des AAH comme l'AMW (average molecular weight), la qnmax (maximum negative charge) et le SPP (submolecular molarity parameter), sont des paramètres cruciaux de l'inhibition commune des OCT1, OCT2 et OCT3 par les AAH. Le CSC est donc un modulateur bifonctionnel, qui peut intervenir dans la régulation de l'activité et de l'expression des transporteurs membranaires hépatiques et rénaux, ainsi que ceux chez la levure. De telles interactions peuvent contribuer à l'altération de la pharmacocinétique des médicaments et des composés endogènes chez les fumeurs, d’où l'évaluation de l'exposition hépatique et rénale au CSC demeure indispensable. / Cigarette smoke can damage every part of our body, causing severe chronic diseases and various types of cancers. It also interacts with drug metabolizing enzymes of phase I and II, and thus contributes to pharmacokinetics disruption of various drugs in smokers. Membrane drug transporters are major actors involved in drugs absorption, distribution and elimination, and some are involved in drug-drug interactions. In addition, membrane drug transporters ensure the flow of vital physiological endogenous molecules, and the elimination of various toxic xenobiotics, not only in mammals but also in unicellular organisms, especially in yeasts. Therefore, this indicates the importance of studying the interaction of cigarette smoke and its contained chemicals with drug transporters. Our results demonstrate that cigarette smoke condensate (CSC) modifies the functional activity and / or expression of several hepatic and renal transporters in vitro in hepatic and / or non-hepatic cellular models, including OATPs (organic anion transporting polypeptide), OCT1 (organic cation transporter 1), BCRP (breast cancer resistance protein) and OAT3 (organic anion transporter 3). A remarkable implication of Ah receptor (AhR) was also demonstrated in MRP4 (multidrug resistance-associated protein), BCRP, OAT2 and OCT1 expression regulation in HepaRG cells exposed to CSC. In addition, in Saccharomyces cerevisiae, CSC inhibits the efflux activity of at least the rhodamine 123 and caffeine transporters, and induces, after three hours, their expression and that of others involved in xenobiotic resistance such as plasma membrane transporters Pdr5, Snq2, Pdr10, Pdr15 and Tpo1. Finally, a remarkable inhibitory effect of heterocyclic aromatic amines (HAA) is demonstrated in vitro, in particular that of Trp-P-1 and Trp-P-2 on the activity of OCT1 and OCT2. In addition, in silico data suggest that molecular descriptors of HAA such as AMW (average molecular weight), qnmax (maximum negative charge) and SPP (submolecular molarity parameter), may represent crucial parameters for common inhibition of OCT1, OCT2 and OCT3 transporters by HAA. Thus, CSC acts as bifunctional modulator, which can regulate activity and expression of hepatic and renal drug transporters as well as some membrane transporters in yeasts. Such interactions may contribute to the alteration of the pharmacokinetics of drugs and endogenous compounds in smokers, hence the evaluation of hepatic and renal exposure to CSC remains essential.
189

Identification and Characterization of a Mutation Causing Stunted Growth in Arabidopsis that is Linked to Phosphate Perception

Shaikh, Mearaj Ahmed A J 12 1900 (has links)
Plant yield is an agronomic trait dependent on the transport of photosynthate from mature source leaves to sink tissues. Manipulating phloem transport may lead to increased yield, however in a previous study, Arabidopsis thaliana overexpressing sucrose transporter AtSUC2 in the phloem resulted in stunted growth and an apparent P-deficiency. In the course of further characterizing the phenotype and identifying the causative mutation, this research included 1) reverse genetics to test genes hypothesized to modulate carbon-phosphate interactions; 2) whole genome sequencing to identify all T-DNA insertions in plants displaying the phenotype; 3) genetic crosses and segregation analysis to isolate the causative mutation; and 4) transcriptomics to capture gene-expression profiles in plants displaying the phenotype. These phenotypes were traced to a T-DNA insertion located on chromosome 4. Transcriptomics by RNA-Seq and data analysis through bioinformatics pipelines suggest disruptions in metabolic and transport pathways that include phosphate, but do not support a direct role of well-established phosphate acquisition mechanisms. Gene At1G78690 is immediately downstream of the T-DNA insertion site and shows modestly increased expression relative to wild type plants. At1G78690 encodes O-acyl transferase, which is involved in processing N-acylphosphotidyl ethanolamine (NAPE) to N-acyl ethanolamine (NAE). Exogenous NAE application causes stunted growth in specific conditions. From the experiments described herein, At1G78690 emerges as the strongest candidate for causing the observed phenotypes.
190

The Norepinephrine Transporter and Its Regulation

Mandela, Prashant, Ordway, Gregory A. 01 April 2006 (has links)
For many years, the norepinephrine transporter (NET) was considered a 'static' protein that contributed to the termination of the action of norepinephrine in the synapse of noradrenergic neurons. The concept that the NET is dynamically regulated, adjusting noradrenergic transmission by changing its function and/or expression, was considered initially in the mid 1980s. Since that time, a plethora of studies demonstrate that the NET is regulated by several intracellular and extracellular signaling molecules, and that phosphorylation of the NET is a major pathway regulating its cell surface expression and thereby its function. The NET is a target of action of a number of drugs that are used long-term therapeutically or abused chronically. This has driven numerous investigations of how the NET and its function are regulated by long-term exposure to drugs. While repeated exposure to many drugs has been shown to affect NET function and expression, the intracellular mechanisms for these effects remains elusive.

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