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1
Davenport, R. "Mechanisms of toxic sodium influx in wheat." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598300.
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Soil salinity constitutes a major limitation to crop productivity in many parts of the world. Wheat is sensitive to high Na+, and this may be because the plant is unable to prevent high Na+ influx into the roots. In this study the crude aspects of Na+ influx were first characterised by measurements of 22Na+ uptake into excised wheat root segments. Transporters responsible for mediating this influx were then screened using the planar lipid bilayer technique as an assay for Na+- permeable ion channels. Four Na+-conducting channels were identified from wheat root plasma membrane preparations. The most abundant channel in the bilayer was a 44 pS channel which was nonselective for monovalent cations and weakly voltage-dependent. Na+ influx through the channel resembled 22Na+ influx into root segments in its sensitivity to inhibition by Ca2+, Mg2+ and Gd3+, and insensitivity to all other inhibitors tested (TEA+, quinine, Cs+, TTX, verapamil, amiloride and flufenamate). The inhibitory effects of multivalent cations were shown to be due to competition for permeation, rather than due to any effects on surface charge. The 44 pS channel also closely resembled an instantaneous current in wheat root protoplasts, thought to represent the main pathway of toxic Na+ influx at the single-cell level (Tyerman et al., 1997). The 44 pS channel and the instantaneous current had the same permeability sequences, same selectivity for K+ over Na+ (≈ 1.25), insensitivity to TEA+, and similar voltage-independence and sensitivity to Ca2+. Thus it appears likely that the 44 pS channel discovered in the bilayer is responsible for the major part of toxic Na+ influx into wheat in saline conditions. The 44 pS channel was not affected by intracellular Ca2+, Mg2+, cyclic nucleotides, ATP, H+, NH4+, or spermine, nor extracellular H+ or glutamate, and therefore did not resemble any nonselective channels identified in other systems. In non-saline conditions the channel could function to catalyse NH4+ uptake for nutrition, and may also play a role in nonselective uptake of cations for osmoregulation. The ability of the channel to catalyse uptake of large cations such as TEA+ suggested that the channel may also have as yet unidentified functions in vivo.
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Chuula, Luyando. "Mass influx refugee situations: law and practice." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/24995.
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The problem of refugees is a global one that is of concern to all states. There are rising numbers of refugees that are forced to migrate from their homes in search of safety. How states respond to refugee situations is very important for the protection of refugee's rights. The international community has been able to draft some international conventions and treaties that provide for the protection of refugees. However, most are drafted in a manner that caters for individual determination and protection procedures. This is despite the fact that refugees enter countries in large groups most times. The major international laws that that cater for group situations are not exact on who must take on the responsibility in mass influx situations, how this responsibility should be shared and also the form and manner that the responsibility sharing mechanisms should take. This research is an insight into the laws and current practise of state in times of mass influx refugee situations. The current crisis in Syria is an example of mass influx situations and how states have been handling the situation and this research analyses the Syrian situation in order to understand current state practice. The research also explores the laws that are currently in place to protect refugees and if they can be applied to mass influx situations while adequately guaranteeing the protection of the human rights of the refugees. It further explores the options that are open to states in times of mass influx, state practice and the obligations that should arise in such situations.
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Lawson, Roderick A. "Neutrophils in bacterial pneumonia : influx and clearance." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/28407.
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A rabbit model of pneumonia was used. Bacteria were instilled bronchoscopically into a localised area, allowing strict timing of pneumonia onset, and study of subsequent evolving processes. Two organisms were used: 1) Streptococcus pneumoniae, an organism characteristic of pneumonia CAP and; 2) Escherichia coli, an organism characteristic of NP. It was hypothesised that in pneumonia due to the former (PneuS), the usual remarkably complete recovery witnessed clinically is due to the tissue load of neutrophils being carefully controlled. By contrast, pneumonia due to the latter (PneuE), is clinically much more severe and lung-damaging, due to a larger lung neutrophil burden. Radiolabelled neutrophils from donor animals were injected at intervals after induction of pneumonia to assess the magnitude of ongoing neutrophil recruitment. In PneuS, neutrophil influx was significantly elevated above control levels at 6 hour but not 30 hour or subsequent time points. In PneuE, neutrophil influx was at least as high at 30 hours as at 6 hours. This confirms the hypothesis that neutrophil influx is more prolonged in PneuE than in PneuS. The animal model demonstrated that neutrophil influx was more prolonged in PneuE than in PneuS. It is suggested this contributes to the more severe clinical manifestations of the former. CD18 was important to the influx of neutrophils in PneuE late as well as early in the disease. Anti-IL-8 antibody failed to inhibit neutrophil influx in either type of pneumonia. Evidence that neutrophil apoptosis is involved in their clearance during pneumonia was obtained, together with evidence that a factor is released to promote neutrophil apoptosis and thus provide negative feedback control of inflammation during pneumonia. The control may differ in PneuS and PneuE, affecting outcome.
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Algharaibeh, Mamoun. "Effect of influx of Eolian materials on soil formation." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/289093.
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The quantity of quartz and its size distribution was determined in soils formed from quartz free basaltic tephra on Greens Peak, Apache County, Arizona. The soils showed a decrease in quartz content from the east side to the west side of the peak. The percentage of averaged weighed quartz content in the upper soil horizons ranged from (36.1%-13.9%) on the east side and (19.9%-12.3%) on the west side. The content of quartz was higher in the surface soil horizons than in the lower horizons. Large amounts of quartz occurred in the sand and silt fraction, whereas no quartz was detected in the clay fractions. Quartz is concentrated mostly in the coarse silt (22-53 μm) fraction (50%). Quartz particle size distribution in these soils is dominantly in the range of 17-53 μm particle count based, and (17-63 μm) mass based. The abundance of silt and very fine sand quartz, and the paucity of aerosolic quartz 1-10 μm in these fractions is indicative of dust transported short distances from the local sources. It is suggested that the quartz was added as loess sized material of mainly local origin brought into the profiles by eolian transport.
5
Posel, Deborah. "Influx control and the construction of Apartheid, 1948-1961." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327979.
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James, Nicholas Paul. "The role of auxin influx carrier in plant development." Thesis, University of Nottingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275958.
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Elton, Jessica. "Contending with privileged influx lessons from Boston's Mission Hill /." Diss., Connect to the thesis, 2004. http://thesis.haverford.edu/54/01/2004EltonJ.pdf.
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Yang, Meng. "Calcium influx, celluar signaling and the biology of candida albicans." Thesis, University of Aberdeen, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.499748.
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FIG1 is a gene that encodes a transmembrane protein involved in calcium influx a process that is important for stress responses in pathogens fungi such as Candida albicans. A Cafig1 null mutant took up less calcium ions in mating than control strains confirming its role in Ca2+ uptake. Furthermore, C. albicans strains with deletions of FIG1 in other calcium channel mutant backgrounds displayed distinctive phenotypes under vegetative growth conditions, which suggested that Fig1 may be a regulator of other calcium influx systems. Using GFP and LacZ reporter constructs it was shown that in C. albicans FIG1 was induced by mating pheromone and during the interactions of strains of compatible mating type. Localization of Fig1-GFP studied by con-focal imaging showed that the protein had a peri-nuclear distribution and was also found in the plasma membrane at the tips of shmoos. The protein appeared to be located within microdomains and the protein sequence was found to contain a putative site for cysteine palmitoylation that may promote such localization. Because the expression of FIG1 was strongly induced during mating, the induction of FIG1 was used to try to detect where mating took place during experimental infection in mice. Surprisingly FIG1 expression could be observed in the murine gut in control inoculations using C. albicans strains that could not undergo mating. Therefore FIG1 expression is not always strictly mating-dependent. MAP kinases and calcium-calcineurin signalling pathways, in which Fig1 is involved, were studied using bioinformatics approaches. It was shown that these signalling pathways contain conserved signalling components taking part in signal transduction via phosphorelay but they had diverged receptors, sensors, effectors, and phosphorelay regulators across different fungal species.
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Bradley, J. E. "The Ca²⺠influx pathways of isolated urethra cells." Thesis, Queen's University Belfast, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431451.
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Adelman, Sammy. "Influx control and the crisis in South Africa : 1979-1986." Thesis, University of Warwick, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328631.
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Vibeke, Eggli Ann. "Mass refugee influx and the limits of public international law /." The Hague : M. Nijhoff publ, 2002. http://catalogue.bnf.fr/ark:/12148/cb39269232j.
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Velmurugan, Naveen. "Distributed dynamics of influx during MPD operations : modelling and estimation." Thesis, Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLM018.
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Lors du forage d’un puits de pétrole, il est courant de subir un influx non désiré de fluides provenant du réservoir. Ce manuscrit porte sur l’étude de la dynamique de l’écoulement en résultant dans le réservoir et le puis, pendant les opérations de forage à pression contrôlée (MPD en anglais). La modélisation repose sur des équations de conservation, qui débouchent sur un modèle d’écoulement biphasique appelé modèle à dérive de flux. Celui-ci prend la forme d’un système hyperbolique d’équations de transport, alors que l’évolution de la pression dans le réservoir suit une dynamique gouvernée par une équation parabolique de diffusion. Nous proposons des schémas numériques permettant d’approcher les solutions de ces deux systèmes dynamiques. Nous synthétisons ensuite des observateurs permettant d’estimer le débit entrant depuis le réservoir. Ces observateurs du système couplé puits-réservoir prennent des formes différentes selon que le caractère distribué de chacune des dynamiques (puits ou réservoir) est négligé ou non. Nos estimateurs reposent sur la mesure de la pression en tête de puits, où un capteur est systématiquement installé dans les opérations de forage à pression contrôlée. L’existence d’un capteur de pression installé au fond du puits, plus rare, modifie la synthèse d’observateurs, d’une manière que nous détaillons. Pour chaque observateur, nous montrons la convergence des estimations de pression et de débit distribués vers leurs valeurs théoriquesWhile drilling an oil well, unwanted influx of fluids from the reservoir may occur. This manuscript studies the dynamics of the resulting fluid flow in the wellbore and the reservoir, during managed pressure drilling (MPD) operations. We study the phenomena using first-principle approach that leads to a modified two phase flow model called the drift-flux model (DFM). The model takes the form of a hyperbolic system of transport equations, whereas the reservoir pressure dynamics is given by a parabolic diffusion equation. We propose appropriate numerical schemes for both. Then, we propose different observer designs to estimate the influx from the reservoir into the wellbore. The observers for the coupled wellbore-reservoir system take different forms, as we combine the distributed and the reduced order models for each system. We propose to use the choke pressure as a measurement that is typically available on a MPD operational site, i.e. topside sensing. However, availability of the bottom hole pressure modifies the observer design, in ways we detail. We show convergence of the observers to the true values of reservoir pore pressure and influx, in each case
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Pejović, Vojislav. "Glutamate induced potentiation of calcium influx in primary hippocampal culture neurons." [S.l.] : [s.n.], 2001. http://ArchiMeD.uni-mainz.de/pub/2001/0027/diss.pdf.
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Kwan, Wai San. "SLCO influx transporters and variability in the disposition of Antiretroviral drugs." Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526797.
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龔振輝 and Chun-fai Frederick Kung. "Influx of Western media to Asia and response of Asian governments." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31267191.
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Tsai, Ke-Li. "Mechanisms of acid influx in the carotid body type I cell." Thesis, University of Oxford, 2003. http://ora.ox.ac.uk/objects/uuid:683bdddf-e8a0-4abb-8d68-35b9188057e0.
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Type I cells of the carotid body play a major role in acid chemoreception. Extracellular acidosis causes membrane depolarisation, Ca2+ influx and neurosecretion in the type I cell. A previous study has shown that pHi in the type I cell is very sensitive to changes of pHo, and intracellular acidification is a key step in the signalling pathway for acid chemoreception. This thesis investigates the mechanism responsible for mediating acid influx during isocapnic extracellular acidosis. Type I cells were enzymically isolated from carotid bodies obtained from neonatal rats. pHi was determined by microspectrofluorimetry, using pH-sensitive fluorescent dye carboxy-SNARF-1. My results show that there are two acid influx pathways. At resting pHi, Cl--HCO3- exchange accounts for over 70% of acid influx in response to extracellular acidosis. The remaining 30% of acid influx is mediated by an unidentified mechanism, which does not require either Cl- or HCO3-. I have also demonstrated that, the second pathway is an acid loading mechanism enhanced by a fall in pHo, rather than an existing background acid loading unmasked by the inhibition of acid extruder. Although 200 µM DIDS inhibited Cl-0-free induced acid efflux mediated by reversed mode of Cl--HCO3- exchange as well as the acid influx induced by alkali load, it had no effect on the acid influx in response to acid challenge. The difference in DIDS effect to block acid influx is probably due to difference in Cl--HCO3- exchangers. I proposed that the Cl--HCO3- exchange system in the type I cell comprises two distinct exchanger populations. One of them is DIDS sensitive and activated by high pHi, while the other is DIDS insensitive and activated by low pHo. The pHi and pHo sensitivity of both acid influx pathways have also been characterised. It is found that the unidentified HCO3--independent acid loading mechanism is activated by H0+ while virtually pHi-independent. In addition, the activity of Cl--HCO3- exchange system is very sensitive to pHi and pHo, with pKai and pKao values close to resting pHi and pHo. Thus any shift of pHi or pHo from the normal resting range will produce significant changes in exchange activity, leading to changes in acid flux into the cell. In this way, the Cl--HCO3- exchange system serves as a link for transducing acidic pH0 into parallel acidification in pHi in the type I cell.
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Kung, Chun-fai Frederick. "Influx of Western media to Asia and response of Asian governments /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1796314X.
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Wang, Fang. "DOES CALCIUM INFLUX THROUGH T-TYPE CALCIUM CHANNEL INDUCE CARDIOMYOCYTE PROLIFERATION?" Diss., Temple University Libraries, 2012. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/214814.
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PhysiologyPh.D.
Cardiovascular disease remains the number one cause or mortally in the western world. Heart failure is the most rapidly growing cardiovascular disease (Hobbs, 2004; Levy, et al., 2002). Heart failure, by definition, is progressive deteriorating function of the heart due to progressive cardiac myocytes loss. Though after decades of endeavor of searching the pathophysiology and treatments for heart failure, it remains highly lethal. Therefore, it is vital to find novel therapies to help treat such chronic disease. Replace the lost cardiomyocyte with new ones could restore cardiac function and reduce mortality. The purpose of this study is to investigate on how TTCCs (T-type calcium channels) affect cardiomyocyte proliferation. In mice after birth, the major TTCC expressed in the heart is Cav3.1/α1G, and therefore we used Cav3.1/α1G transgenic (TG), knockout (-/-) and wild type mice respectively to define the role of TTCC in cardiomyocyte proliferation. In neonatal mouse ventricular myocyte (NMVMs) right after birth, there is almost no TTCC after birth in α1G-/- NMVMs, whereas there are around 35% NMVMs in wild type (WT) show TTCC. On day 7 after birth, there are no T-type calcium currents in both α1G-/- NMVMs and WT NMVMs. Using BrdU, a DNA synthesis marker, we identified plenty of BrdU positive cardiomyocyte during the first seven days after birth. Cardiomyocyte is special due to its double nucleation property. Our cell cycle studies showed that there is significant difference in cell cycle distribution between α1G-/- and WT NMVMs on day seven after birth. Significantly more NMVMs are arrested in G1 phase in α1G-/-, compared to WT NMVMs. Even until 2 month old, there are still significantly more mono-nucleated cardiomyocyte in α1G-/- than in WT. In conclusion, all these evidence showed that blocking T-type calcium channel could partially prevent binucleation from happening and stop cardiomyocytes withdrawal from cell cycle. Mononucleated cardiomyocyte is still able to proliferate. Hence, mononucleated cardiomyocytes in adult still have potential to proliferation because these cardiomyoctes are arrested in their cell-cycle before their terminal differentiation, which could offer a novel approach for cardiac repair.
Temple University--Theses
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Shen, Ying. "Regulation of Ca2+ influx by cell shape in Swiss 3T3 cells." Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548807.
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Pineda, Christopher Julius. "Finding a Home: Latino Residential Influx into Progress Village, 1990-2010." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/6014.
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Progress Village in Tampa Florida was developed in the late 1950s in response to the dislocation of black families during the construction of Interstate-4. Furthermore this community became an opportunity for many black and more specifically, African American families, to live in a community devoid of racist attitudes and tensions rampant in inner city Tampa at the time. For over thirty years this community’s residential population was overwhelmingly (90 percent) black or African American. In the 1990s though this community would begin to experience the first wave of Latino residents and by 2000 this group would comprise over 2 percent of the population. Moreover by 2010 this community’s Latino population would soar to over 14 percent of the total population. This project is a case study of Latino migration into a small historically Black residential community. This work examines a plethora of sources ranging from newspaper articles (New York Times, Sun Sentinel, Progress Village Pioneer, etc.), scholarly articles, government data (U.S. Census), and primary research in the form of survey data and interviews from current Latino residents. All these sources are incorporated to argue that evolving federal immigration policies, shifting migration patterns, and economic factors (affordable housing and employment) all played a vital role in this recent and ongoing influx. This research adds to the existing scholarship of Latino migration in the U.S. by demonstrating how small predominantly African American communities like Progress Village are diversified by all these factors.
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Paiva, Almino Afonso de Oliveira. "Avalia??o de uma fra??o polissacaridica da alga Lobophora variegata (Lamouroux) em modelo de artrite induzida em ratos por Zymosan." Universidade Federal do Rio Grande do Norte, 2010. http://repositorio.ufrn.br:8080/jspui/handle/123456789/18532.
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Previous issue date: 2010-09-13Fucans seaweed Lobophora variegata estructures are known for their chemical and biological properties. In this study, we analyzed, the action of fucans L. variegata and the fractions purified with acetone in Zymosan-induced arthritis. After differential fractionation with acetone, six fractions were obtained and named F0.3, F0.5, F0.8, F1, F1.5 and F2. The results showed that the fraction F1 showed high yield (51.9%) and was chosen for studies of antioxidant activity and induced arthritis. Nuclear magnetic resonance (NMR) of 13C showed signals at 103.3 and 15.78 ppm that are assigned to links ?13 galactose and of the C6 methyl fucose, respectively. The infrared (IR) showed absorbance at 1238 and 850 cm-1 which are attributed to sulfate. The fraction F1 showed antioxidant activities in vitro. For analysis of inflammatory parameters chosen the polysaccharide was administered in different doses (25, 50 and 75 mg / kg ip, per body weight) and diclofenac sodium (5 mg / kg ip) and L-NAME (25 mg / kg ip) in groups of animals (n = 6). After 6 h, were analyzed for cellular influx and levels of nitrite. In experiment five days, were made analysis of swelling and serum TNF-?. Histopathological analysis were performed for confirmation of results. The fraction F1 (25, 50 and 75 mg / kg ip) reduced the cellular influx (52.1 to 96.7%) and nitric oxide levels (27.2 - 39%) compared to control group. The reduction of edema (63.4 - 100%) and serum TNF-? (p <0.001) were observed when the polysaccharide F1 administered at a dose (50 mg / kg) These results suggest that these heterofucanas of Lobophora variegata have besides the activity antioxidant and potential anti-inflammatory activity in arthritis induced by zymosan
Fucanas da alga Lobophora variegata s?o conhecidas por suas estruturas qu?micas e propriedades biol?gicas. Nesse estudo, analisou-se a a??o de fucanas de L. variegata e suas fra??es purificadas com acetona na artrite induzida por Zymosan. Ap?s fracionamento diferencial com acetona, 6 fra??es foram obtidas e nomeados F0.3, F0.5, F0.8, F1, F1.5 e F2. Os resultados mostraram que a fra??o F1 apresentou alto rendimento (51,9%) e foi escolhida para estudos da atividade antioxidante e artrite induzida. A resson?ncia magn?tica nuclear (RMN) de 13C mostrou sinais a 103,3 e 15,78 ppm que s?o atribu?dos ?s liga??es ?1 3 da galactose e metil do C6 da fucose, respectivamente. O infravermelho (IV) mostrou absorb?ncia a 1238 e 850 cm-1 que s?o atribu?das ao sulfato. A fra??o F1 apresentou atividades antioxidantes in vitro. Para an?lise de par?metros inflamat?rios a fra??o polissacar?dica escolhida foi administrada em diferentes doses (25, 50 e 75 mg/kg i.p, por peso corporal), assim como diclofenaco de s?dio (5 mg/kg i.p.) e L-NAME (25 mg/kg i.p.) em grupos de animais (n=6). Depois de 6 h, foram realizadas an?lises de influxo celular e n?veis de nitrito. Em experimento de cinco dias, foram efetuadas analises de edema e TNF-? s?rico. An?lises histopatol?gicas foram realizadas para confirma??o de resultados. A fra??o F1 (25, 50 e 75 mg/kg i.p.) reduziu o influxo celular (52,1 ? 96,7%) e os n?veis ?xido n?trico (27,2 ? 39%) em rela??o ao grupo controle. A redu??o do edema (63,4 - 100%) e TNF-? s?rico (p < 0,001) foram observadas quando administrado o polissacar?deo F1 na dosagem (50 mg/kg) Esses resultados sugerem que essas heterofucanas de Lobophora variegata possuem al?m da atividade antioxidante, potencial atividade anti-inflamat?ria na artrite induzida por zymosan
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Tomoda, Takako School of Sociology UNSW. "The loanword (Gairaigo) influx into the Japanese language: contemporary perceptions and responses." Awarded by:University of New South Wales. School of Sociology, 2005. http://handle.unsw.edu.au/1959.4/22997.
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Loanwords have been entering Japanese for centuries but the rate has accelerated postwar and the predominant source is English. Gairaigo have received a mixed response from scholars, government, the media and the public. Opponents claim they cause confusion and have called for limits to protect the language and culture. From the 1980s, language planning bodies turned their attention to gairaigo and, in the early 2000s, took steps to limit their use. This research examines and evaluates the perceptions and responses of Japanese people and language planners to gairaigo over this period. Scholarly and popular works, the media, and policy discussions by language planners were analysed under the rubric of corpus planning proposed by Ferguson (1979) and Cooper (1989). The level of purism was evaluated within the framework of Thomas (1991). To obtain quantitative data on public perceptions of gairaigo, a survey was conducted and the results compared with published opinion poll data. Scholars who supported gairaigo concentrated on its enrichment of the corpus, imagery, nuance, and its internationalising effects. Opponents focused on the confusing nature of new gairaigo particularly for older people, damage to the language and culture, creation of social divisions, and excessive Westernisation. Both globalisation and universal English education were considered causes of the influx. Policy discussions focused on comprehension levels of new gairaigo, generational differences, and overuse of gairaigo by government, especially in aged care. Lists of replacement words were produced but public response has been mixed. A majority of people surveyed expressed negative views of gairaigo, but only a small minority held strong views. Most were tolerant of gairaigo use and were willing to use new gairaigo. Tolerance decreased with age but there was no clear relationship with English language ability. Opinion poll data did not demonstrate any longitudinal increase in negative views of gairaigo over the 1980s and 90s. It was concluded that public support for government intervention was generally weak and was not assisted by the archaising approach taken to replacing gairaigo with kango. Recommendations for alternative responses were made.
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Burwell, Isaac Ronald. "The responses of diatoms to the influx of tephras into lacustrine environments." Thesis, University of Canterbury. Geology, 2003. http://hdl.handle.net/10092/6775.
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The aim of this research is to determine the response of diatoms to the deposition of tephras into lake environments. This is achieved by conducting high-resolution sampling of cores extracted from Lake Pupuke and Pukaki Crater; two maar lakes located in the Auckland Volcanic Field, and by analysing the diatom floras directly above and below selected tephra beds.
Tephras were selected for differing composition and thickness. Nine tephras were selected: four TVZ rhyolitic tephras, two Taranaki Volcano andesitic tephras, and three locally derived A VF basaltic tephras, ranging from 2 mm to 20 cm in thickness.
Eight of the sections record changes across the tephra bed; however, the mechanisms of response are not consistent between tephras of different composition or thickness.
The most common diatom recorded at both sites is Cyclotella stelligera, and in a majority of the sections, tephra input increases the dominance of this taxon. Tephra input has no impact on many environmental variables, e.g. the pH, salinity, nitrogen availability and oxygen saturation levels of the lake waters. Trophic status is most readily altered by the influx of tephra, generally recording a reduction in nutrient levels above the tephra.
The most common mechanism of response, recorded in three sections, is a reduction in phosphorus after tephra input probably due to the sealing off of underlying sediments by the tephra layer, thereby blocking the recycling of P from pre-tephra deposits. Other responses include effects associated with the physical properties of tephra particles interacting with diatom habitats, i.e. smothering of epiphytic habitats, and decreased turbulence in planktonic environments. Tephra also alters the relationship between Synedra ulna and a teratological variety of Synedra ulna v spathulifera. Suprisingly, thickness and chemical composition do not influence the response of the diatom assemblage.
Five of the nine sections also indicate that the tephras sank through the underling sediment, coming to rest up to 1.75 cm below their original stratigraphic position. This is recorded as an offset between the tephra depth and the depth where changes in diatom assemblage are recorded. The most likely mechanism appears to be grain-by grain dissemination of tephra particles through the unconsolidated sediment at the sediment/water interface. Thickness and chemical composition of tephra do not appear to influence these events.
The identification of displaced tephras has major implications in all paleoenvironmental reconstructions which utilise tephrachronology and tephrastratigraphy as dating and correlating tools. In particular, tephras may not constitute absolute time markers.
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Martucci, Tony. "Characterisation of a family of putative auxin influx carrier genes in strawberry." Thesis, Nottingham Trent University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272805.
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Yemm, Anthony Alan. "Molecular characterisation of the putative auxin influx carrier, AUX1 from Arabidopsis thaliana." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250523.
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McVicker, Clare Geldard. "Calcium influx mechanisms during mediator-induced responses in human airway smooth muscle." Thesis, King's College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404814.
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Quément, Fanny. "« Mutable as sound » : mutations des influx sonores dans l’œuvre de Seamus Heaney." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCA113.
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Cette thèse interroge la présence et les métamorphoses du son dans l’œuvre de Seamus Heaney, avec pour perspective la confrontation de l’expérience du texte imprimé à celle d’un corpus audio. En nous penchant sur les essais, les poèmes et les enregistrements commercialisés de l’auteur, nous retraçons le parcours des influx sonores depuis la perception des ondes dans l’environnement jusqu’à l’émission de la voix en passant par leur recréation dans le texte. Parler d’« influx sonores », c’est raviver la métaphore aquatique dans la catachrèse des « ondes », mais aussi inviter à détecter des courants souterrains et à prendre en compte leur réception et leur absorption par l’auditeur autant que leur diffusion.Afin de montrer que chaque poème constitue un événement sonore à part entière, nous analysons le processus par lequel l’environnement sonore est transformé en un paysage sonore poétique, à son tour placé dans de nouveaux environnements par le biais de la performance orale. L’éclairage apporté par les Sound Studies nous permet de souligner le caractère dynamique mais aussi la fugacité du son, d’identifier et de discuter les propriétés conductrices d’une écriture qui accueille aussi le silence en son sein, ainsi que de conceptualiser, avec Heaney, la notion d’écoute. Nos micro-lectures sont aussi des micro-écoutes qui vont jusqu’à tenir compte de la dimension phonétique des textes, notre étude de la voix poétique étant complétée par une analyse de la voix physique. En considérant le graphotexte, le phonotexte et l’audiotexte comme trois modes d’existence non-hiérarchisables d’un même poème, nous cherchons à approfondir et nuancer les recherches sur la prosodie de Heaney, qui dépasse de loin la versification classique, voire formaliste, à laquelle on l’a souvent assimiléeThis thesis questions the presence and metamorphoses of sound in the works of Seamus Heaney, ultimately bringing the experience of the printed text and that of audio recordings into comparison. Based on a study of the author’s essays, poems and commercialised recordings, it retraces the trajectory of sound influxes from the perception of soundwaves in the environment to the emission of the voice, via their recreation in writing. The phrase “sound influx” is meant to revive the aquatic metaphor in the catachretic compound “soundwave.” It also invites to detect undercurrents by ear and study them from the perspective of the listener, taking into account their reception and absoption as much as their broadcasting.In order to show that each poem is a sound event of its own kind, it analyses the process through which the sonic environment is turned into a poetic soundscape which then becomes part of other environments when orally performed. Borrowing concepts from Sound Studies, it highlights the dynamic but elusive nature of sound, identifies and questions the conductive properties of a writing that also makes room for silence, and reflects, along with Heaney, on listening as a notion.The close-readings developed here are also close-listenings that take into account the phonetic dimension of texts, the study of the poetic voice being completed by an analysis of the poet’s physical voice. Considering the graphotext, the phonotext and the audiotext as three equally significant incarnations of one poem, aims at bringing a nuanced perspective on Heaney’s prosody as it is too often reduced to formal – if not formalist – versification
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Makarewich, Catherine Anne. "MICRODOMAIN BASED CALCIUM INFLUX PATHWAYS THAT REGULATE PATHOLOGICAL CARDIAC HYPERTROPHY AND CONTRACTILITY." Diss., Temple University Libraries, 2014. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/266828.
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Molecular and Cellular PhysiologyPh.D.
Pathological cardiac stressors, including persistent hypertension or damage from ischemic heart disease, induce a chronic demand for enhanced contractile performance of the heart. The cytosolic calcium (Ca2+) transient that regulates myocyte contraction must be persistently increased in disease states in order to maintain cardiac output to sustain the metabolic requirements of the body. Associated with this enhanced intracellular Ca2+ ([Ca2+]i) state is pathological cardiac myocyte hypertrophy, which results in large part from the activation of Ca2+-dependent activation of calcineurin (Cn)-nuclear factor of activated T cells (NFAT) signaling. The puzzling feature of this hypertrophic signaling is that the cytosolic [Ca2+] that controls contractility appears to be separate from the [Ca2+] which activates Cn-NFAT signaling. The overarching theme of this dissertation is to explore the source and spatial constraints of pathological hypertrophic signaling Ca2+ and to investigate how it is possible that sensitive and finely tuned Ca2+-dependent signaling pathways are regulated in the background of massive Ca2+ fluctuations that oscillate between 100nM and upwards of 1-2μM during each cardiac contractile cycle. L-type Ca2+ channels (LTCCs) are a major source of Ca2+ entry in cardiac myocytes and are known to play an integral role in the initiation of myocyte excitation contraction-coupling (EC-coupling). We performed a number of experiments to show that a small population of LTCCs reside outside of EC-coupling domains within caveolin (Cav-3) signaling microdomains where they provide a local source of Ca2+ to activate Cn-NFAT signaling. We designed a Cav-targeted LTCC blocker that could eliminate Cn-NFAT activation but did not reduce myocyte contractility. The activity of Cav-targeted LTCCs could also be upregulated to enhance hypertrophic signaling without affecting contractility. Therefore, we believe that caveolae-localized LTCCs do not participate in EC-coupling, but instead act locally to control the coordinated activation of Cn-NFAT signaling that drives pathological remodeling. Transient Receptor Potential (TRP) channels are also thought to provide a source of Ca2+ for activation of hypertrophic signaling. The canonical family of TRP channels (TRPC) is expressed at low levels in normal adult cardiac tissue, but these channels are upregulated in disease conditions which implicates them as stress response molecules that could potentially provide a platform for hypertrophic Ca2+ signaling. We show evidence that TRPC channel abundance and function increases in cardiac stress conditions, such as myocardial infarction (MI), and that these channels are associated with hypertrophic responses, likely through a Ca2+ microdomain effect. While we found that TRPC channels housed in caveolae membrane microdomains provides a source of [Ca2+] for induction of cardiac hypertrophy, this effect also requires interplay with LTCCs. We also found that TRPC channels have negative effects on cardiac contractility, which we believe are due to local activation of Ca2+/calmodulin-dependent protein kinase (CaMKII) and subsequent modulation of ryanodine receptors (RyRs). Further, we found that inhibiting TRPC channels in a mouse model of MI led to increased basal myocyte contractility and reduced hypertrophy and cardiac structural and functional remodeling, as well as increased survival. Collectively, the data presented in this dissertation provides comprehensive evidence that Ca2+ regulation of Cn-NFAT signaling and resultant pathological hypertrophy can be coordinated by spatially localized and regulated Ca2+ channels. The compartmentalization of LTCCs and TRPC channels in caveolae membrane microdomains along with pathological hypertrophy signaling effectors makes for an attractive explanation for how Ca2+-dependent signaling pathways are regulated under conditions of continual Ca2+ transients that mediate cardiac contraction during each heart beat. Elucidation of additional Ca2+ signaling microdomains in adult cardiac myocytes will be important in more comprehensively resolving how myocytes differentiate between signaling versus contractile Ca2+.
Temple University--Theses
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DeJong, Danica. "Calcium Alleviates Symptoms in Hyperkalemic Periodic Paralysis by Reducing the Abnormal Sodium Influx." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23487.
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Hyperkalemic periodic paralysis, HyperKPP, is an inherited progressive disorder of the muscles caused by mutations in the voltage gated sodium channel (NaV1.4). The objectives of this thesis were to develop a technique for measurement symptoms in vivo using electromyography (EMG) and to determine the mechanism by which Ca2+ alleviates HyperKPP symptoms, since this is unknown. Increasing extracellular [Ca2+] ([Ca2+]e) from 1.3 to 4 mM did not result in any increases in45Ca2+ influx suggesting no increase in intracellular [Ca2+] ([Ca2+]i) acting on an intracellular signaling pathway or on an ion channel such as the Ca2+sensitive K+ channels. HyperKPP muscles have larger TTX-sensitive22Na+ influx than wild type muscles because of the defective NaV1.4 channels. When [Ca2+] was increased from 1.3 to 4 mM, the abnormal 22Na+ influx was completely abolished. Thus, one mechanism by which Ca2+alleviates HyperKPP symptoms is by reducing the abnormal Na+ influx caused by the mutation in the NaV1.4 channel.
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Garrett, Jasmine Jay Tamara, and University of Lethbridge Faculty of Arts and Science. "Autobahn : a gene that has a role in auxin influx in Arabidopsis leaves." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2005, 2005. http://hdl.handle.net/10133/258.
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The development of leaf vascular patterns is a highly regulated process. The plant hormone
auxin is critical for vascular patterning: auxin canalization is proposed to cause files of cells to accumulate higher auxin levels and develop into veins. Thus, the response of cells to auxin and transport of auxin are critical to establish proper cell fate. We have characterized a mutation in the Arabidopsis thaliana gene name AUTOBAHN (ABN). abn leaves produce leaves that proliferate disorganized, overlapping veins parallel to the midvein with no differentiation of higher order veins. abn leaves show no normal aspects of the secondary auxin response though double mutant analysis suggest that ABN functions independently of previously characterized auxin response pathways. Wild type plants grown on an influx inhibitor phenocopy abn suggesting that abn is defective in carrier-mediated auxin influx.x, 69 leaves : ill. ; 28 cm.
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Cryer, Nicholas Colin. "The cloning and characteristion of anion influx and efflux transports from higher plants." Thesis, Royal Holloway, University of London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269798.
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Oliver-Evans, Ceridwen. "The implications of the abolition of influx control legislation in the Western Cape." Master's thesis, University of Cape Town, 1992. http://hdl.handle.net/11427/22412.
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Bibliography: pages 259-277.Influx control legislation was formally abolished in South Africa in 1986. This thesis investigates the social processes set in motion with its abolition in the spheres of employment and urbanisation and argues that the way in which influx control has been defined is central to any analysis concerned with its abolition. In this regard, influx control has been viewed in two senses: a narrow one in which it has been equated with formal influx control legislation, 'the pass laws'; and, secondly and more broadly, through definitions which embrace all methods of control over African urbanisation and associated labour mobility. This thesis argues that, in the macro domain, while influx control in its narrow sense has been abolished, it has been replaced with far more complex and subtle forms of control. These ostensibly racially neutral measures, an 'orderly urbanisation' policy and a wide variety of laws existing on South African statute books continue to circumscribe African rights. The research focuses on a specific region, the Western Cape, an area where influx control has been more harshly implemented than elsewhere through the implementation of the Coloured Labour Preference Policy. This thesis investigates on a micro-level, via the medium of a company compound, how people at both an individual and institutional level have interpreted the legislative changes and acted upon them. The particular range of actors include government officials, employers and employer organisations, union representatives, and migrant workers and their families living in the company compound. The evidence I present was obtained primarily through interviews and ethnographic field-research conducted in 1988. A particular concern of the thesis has been to examine the disjunction between policy and practice as pursued by government officials and the effects and implications arising from this among the actors mentioned above. The main themes which have emerged from this research are those of confusion and a lack of knowledge among many of the informants. It was found that high-ranking government officials lack consensus on vital issues of citizenship and employment which affect the lives of thousands of Transkeian and Ciskeian citizens. Employers, confused by the confusion in government departments, and confronted by a new situation and new sets of rules have either ignored these or succumbed to government policy. Equally, unions have been slow to respond or systematically adopt a policy on the 1986 legislative changes. Finally, it was found that migrant workers and their families are availing themselves of opportunities presented by the abolition of influx control legislation in terms of freedom of movement, although as I argue, this takes the form of a complex range of fluid and dynamic movement patterns between the compound, the rural areas and urban townships. This complexity, as the thesis demonstrates, is reflected both in the attitudes and in the practical daily living arrangements of the workers as they respond to and interpret the macro-level forces which affect them.
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Hoffman, Nicholas. "Mitochondrial Calcium Influx is Determined by Multiple Protein Components Including SLC25A23 and MICU1." Diss., Temple University Libraries, 2014. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/287159.
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BiochemistryPh.D.
Ca2+ control mechanisms employed by the cell at the plasma membrane include receptor operated, voltage-sensitive, and store operated channels for Ca2+ import. Upon entry into the cytosol, Ca2+ is sequestered by Ca2+ binding proteins, the endoplasmic reticulum (ER), or by mitochondria. The largest Ca2+ store in the cell is the ER where Ca2+ levels approach millimolar levels. The ER regulates cytosolic Ca2+ homeostasis by using Ca2+ binding proteins, the SERCA pump, second messenger Ca2+ release upon IP3 receptor activation, and Ca2+-induced Ca2+ release by ryanodine receptors. Basal cytosolic Ca2+ levels are maintained at around 100nM. The mitochondria begins clearing GPRC-depended cytosolic Ca2+elevation after a short time delay during which the cytosolic Ca2+ concentration exceeds 3M. Then, the mitochondria sacrifices a portion of its membrane potential to drive Ca2+ influx across the mitochondrial inner membrane into the matrix. The membrane potential of the mitochondria is created in part by the electron transport, which while transferring electrons, ejects protons from the matrix to the inner membrane space. The rapid mitochondrial Ca2+ uptake decreases mitochondrial membrane potential thus reducing or fully collapsing the mitochondria's ability to generate ATP. This uncoupling of the electron transport chain results in ROS production and decreased cell survival. Mitochondria provide the body with energy that allows a heart to beat, a brain to store memories, and fuels locomotive function. As a stand-alone energy generator, the mitochondria would be interesting, but not dynamic. The dynamic flow of information to the mitochondria through Ca2+ signaling with all the components of symbiotic precision is a true biological phenomenon. In the mitochondria, a complex Ca2+ buffering system of channels, pores, and exchangers directly affects the conversion of chemical potential to ATP. Recent, discoveries of the Ca2+ uniporter (MCU) and other system components have provided the tools to tackle levels of mitochondrion physiologic studies that were not possible only a couple of years ago. There remains a great need for advancement in the understanding of mitochondrial bioenergetics, and undoubtedly, the mitochondria will be viewed as a determinant factor for survival. The mitochondrial inner membrane through its curious construction of 3:1 protein to lipid ratio, carefully regulates the permeability of ions and metabolites. The transport of Ca2+ and other small ions across the inner membrane is an essential signaling pathway for mitochondrial maintenance of metabolic functions, but the mechanisms are still unclear due to a lack of mitochondrial systems biology. For example, the oligomeric MCU with two transmembrane domains is a core component of the major Ca2+ import pathway in mitochondria, and ablation of MCU lowers mitochondrial Ca2+ uptake, however portions such as the highly conserved linker between the two transmembrane was unstudied until recently. Other complex components such as MICU1 and MCUR1, which negatively and positively regulate MCU, are beginning to have their mechanism solved. MICU1 is associated with the mitochondrial inner membrane and has two EF hands, which indicated a possible role in Ca2+ sensing. This role as a Ca2+ sensor proved to be necessary for proper MICU1 inhibition of MCU, but not determinant of MICU1/MCU interaction. MICU1, MCUR1, and MCU are modified in numerous diseases in which a particular component is disproportionately expressed. This is in part due to the classical coupling of gene function to associated transcription factor meaning that because MICU1, MCUR1, and MCU have a Ca2+ flux function, their transcription is also probably controlled by Ca2+ and is altered in chronic inflammation or hypoxic systems such as Ca2+ overload during ischemia/reperfusion. In spite of the low affinity of uniporter, mitochondrial Ca2+ overload occurs due to the close proximity of mitochondria to the ER, however physical tethering of the mitochondria and ER is still not widely accepted. When Ca2+ is physiologically cleared from the cytosol to the mitochondria, it acts as a synchronizing signal to the numerous EF hands present on inner membrane transmembrane proteins and matrix-targeted proteins. . Synchronization of mitochondrial activities is critical for efficiency which has direct implication for both cell growth or damage through the byproduct of inefficiency, mROS (superoxide). Therefore, the EF hands and other Ca2+ response elements enhance the ratio of ATP to superoxide, thus supporting mitogenic function and healthy growth. The inefficient flow of energy leads to dysfunction such as the release of reactive oxygen species (ROS) from the mitochondria. ROS carries its own energy in the chemical form of a radical. This translates into thermodynamically favorable but harmful cellular damage. Sustained import of Ca2+ results in electron transport malfunction followed by loss of membrane potential as seen in ischemia. A common EF hand motif exists on many calcium sensitive proteins. This helix-loop-helix topology recognizes a specific range of calcium concentrations based on the primary and tertiary structure of the domain. Thus, not all EF hands are active at a given physiological Ca2+ concentrations. The Ca2+ is situated in the loop portion by 12 key interactions in a pentagonal bipyramidal geometry. The position of 12th residue supplies two of the interacting oxygen atoms for Ca2+ binding and are conserved as either Glutamate or Aspartate. EF-hand containing proteins do not necessarily transport Ca2+ alone, as many other solutes have also been reported. The EF hand motif can be found on many mitochondrial sensors including LETM-1, MICU1, and non- Ca2+ transporters (Nakayama, Moncrief et al. 1992), suggesting Ca2+ is often the synchronizing signaling molecule but not necessarily transported by the mitochondrial channel of interest. The discovery of the uniporter (MCU) is an exciting event in the field, as many relationships between different transport mechanisms affecting Ca2+ and membrane potential will be elucidated. One such relationship that should be explored is between the uniporter and inorganic phosphate exchange. This relationship may modulate cell death through a critical uptake dynamic between adenine, phosphate and Ca2+ through alternative pathways such as solute carriers. Mitochondrial carriers are crucial for transport across the inner membrane. There are two groups of Ca2+ binding solute carriers in the mitochondria, the aspartate/glutamate carriers (Palmieri, Pardo et al. 2001) and the ATP-magnesium carriers (SCaMC) (Satrustegui, Pardo et al. 2007). Carrier proteins transport molecules by changing shape and therefore can be saturated. Solute carrier activators have been previously reported to include Ca2+, adenosine 3'5'-cyclic monophosphate, protein kinases, and inositol polyphosphates (Dransfield and Aprille 1993). Other previous work has also reported transport of multiple different solutes (Fiermonte, De Leonardis et al. 2004). The higher eukaryote, vertebrate calcium systems, should functionally if not physically interact with conserved lower eukaryote systems such as solute carriers. All known mitochondrial carriers are members of the same family based on three tandem repeats and are predicted to function as oligomers. The human family of these inner mitochondrial membrane proteins is SLC25, and members of the SLC25 family have been identified as the cause of Stanley Syndrome and Amish Microcephaly suggesting the importance of SLC25. SLC25A23 has been proposed to be an ATP-Mg/Pi exchange carrier that allows for both uptake and release of ATP-Mg from mitochondria. As a putative ADP/Pi translocase, it is an interesting component as both ADP and Pi have been shown to play a role in cell survival and cell death. This SLC25A family member is likely to be the critical regulator of these two dynamic molecules. These carriers are stimulated by submicromolar Ca2+ to regulate adenine nucleotide levels in the cytosol and mitochondria. Previous literature has shown SLC25A25 knockout to have little effect on mouse metabolism. SLC25A24 has been shown to be involved in ADP/ATP ratios in the mitochondrial matrix resulting in cytosolic Ca2+ buffering enhancement (21). The functions of SLC25A23 largely remain unknown. It should be pointed out that SLC25A23, SLC25A24, and SLC25A25, Ca2+ induced changes, are not necessarily based on Ca2+ as a channel solute. The ATP/ADP maintained by SLC25 family members may contribute to Ca2+ uptake in the mitochondria and therefore may play a role in cell death through PTP opening. PTP opening is a point of convergence for many cell death pathways. The PTP, which behaves as a voltage-operated channel, can be triggered to open by high mitochondrial Ca2+, ROS, or low membrane potential. In previous studies, SLC25A24 knockdown resulted in increased PTP opening and decreased Ca2+ buffering. Solute carrier family 25 (mitochondrial carrier; phosphate carrier), which includes SLC25A23, SLC25A24, and SLC25A25, transport solutes across the inner membrane, are predicted to form six transmembrane domains sensitive to Ca2+ due to four Ca2+ binding EF hand motifs, and localize to the mitochondria (del Arco and Satrustegui 1998; Iijima, Yamamoto et al. 2001). Based on membrane topology predictions, SLC25 isoforms contain six transmembrane domains with several EF hand motifs. Although the solute carriers in the SCaMC family have been hypothesized to transport adenine, (Aprille 1988) they have never been fully characterized. Mitochondrial solute carriers are found only in eukaryotes (Carafoli and Lehninger 1971; Uribe, Rangel et al. 1992; Palmieri 2004), however Sal1 in yeast has high sequence homology (Kucejova, Li et al. 2008). SLC25A25 knockout was reported to have little effects on mouse metabolism. SLC25A24 has been shown to be involved in ADP/ATP ratios in the mitochondrial matrix resulting in cytosolic Ca2+ buffering enhancement (Traba, Del Arco et al. 2011). The functions of these solute carriers in mitochondrial Ca2+ uptake and mitochondrial ROS are largely unknown.
Temple University--Theses
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Iwakura, Toshio. "Sustained enhancement of Ca[2+] influx by glibenclamide induces apoptosis in RINm5F cells." Kyoto University, 2001. http://hdl.handle.net/2433/150204.
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Sawamura, Seishirou. "Elucidation of signal regulation by interacting molecules and proteins of Ca2+ influx channels." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215579.
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De, Paula Daisy Maria Bentes [UNIFESP]. "Estudo do mecanismo molecular de transfecção mediada por ultrassom." Universidade Federal de São Paulo (UNIFESP), 2010. http://repositorio.unifesp.br/handle/11600/9564.
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Made available in DSpace on 2015-07-22T20:50:09Z (GMT). No. of bitstreams: 0
Previous issue date: 2010-11-24O ultrassom (US) vem sendo amplamente utilizado para melhorar a eficiência de transfecção de vetores não-virais. No entanto, o mecanismo pelo qual o US promove a entrega de DNA nas células ainda é pouco entendido. Este fenômeno é normalmente atribuído a sonoporação. Porém, com base em experimentos anteriores realizados em nosso laboratório, suspeitamos que outro mecanismo esteja envolvido no processo de captação de DNA. Para estudar o mecanismo de entrega, um vetor plasmideal expressando EGFP (pEGFP-N3, 4,7 kb) foi utilizado para transfectar células NIH3T3 com um aparelho de US terapêutico sem a adição de microbolhas. Em condições de insonação de 2 W/cm2, duty cycle de 20% por 30s o US promoveu cerca de 40% de eficiência de transfecção, mas com 1 W/cm2 resultou em níveis muito baixos de transfecção. Fixados esses parâmetros, também foi avaliada a produção de espécies reativas de oxigênio (ROS), o aumento da concentração intracelular de cálcio ([Ca2+]i) e as alterações no potencial de membrana através de microscopia confocal. A produção de ROS foi aumentada durante a insonação, sendo interrompida logo que o US foi desligado. A [Ca2+]i também foi aumentada durante a exposição ao US, mas seus níveis não retornaram ao basal durante os 3 minutos de observação. Porém, 1 W/cm2 não foi suficiente para mobilizar o cálcio durante a insonação, e o influxo de cálcio teve início apenas 12 segundos após o término do US. Quando expostas ao US, as células também apresentaram mudanças no potencial de membrana atingindo um estado de hiperpolarização, retornando ao estado normal logo que o US foi desligado. A alteração desses três parâmetros pelo US sugere que a entrega de DNA plasmideal deva ocorrer por endocitose. Por fim, utilizando DNA plasmideal fluorescente, mostramos que esta molécula entra na célula via endocitose mediada por clatrina.
Ultrasound (US) has been widely used to improve the efficiency of non-viral vector transfection. However, the mechanism that enables the uptake of plasmid DNA in cells by US insonation is poorly understood, but it is typically attributed to sonoporation. Based on our previous results, we hypothesized that other mechanisms, such as endocytosis, are involved in this process. To explore the mechanism of plasmid DNA uptake, a plasmid vector expressing EGFP (pEGFP-N3: 4.7 kb) was used to transfect NIH3T3 cells using a therapeutic US without microbubbles and was monitored in real-time using a confocal microscope. We achieved about 40% transfection efficiency when we applied 2 W/cm2 with 20% of duty-cycle for 30 s, but 1 W/cm2 resulted in a very low level of transfection. In these experiments, the production of reactive oxygen species was augmented during the insonation but was stopped soon after turning off the US. Calcium influx was also augmented during the insonation, but its level did not return to basal levels following the 3-min observation period. However, 1 W/cm2 was not sufficient to mobilize calcium influx during the insonation, and calcium influx began 12 s after turning off the US. US insonation also changed the cell membrane potential to promote a hyperpolarization state, which returned to the normal state soon after turning off the US. The alteration of these parameters by US indicates the uptake of plasmid DNA by endocytosis. Finally, using a fluorescently labeled plasmid, we showed that this molecule enters into cells via clathrin-mediated endocytosis, not via caveolin-1.
TEDE
BV UNIFESP: Teses e dissertações
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Parry, Geraint. "Investigating the mechanisms of auxin transport." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391391.
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Kortekaas, Phaedra. "Development and function of calcium influx in pyramidal neurons of the hippocampal CA1 region." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/55584.
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Obolensky, Anna. "Pharmacological modulation of calcium influx in freshly isolated rat lymphocytes and lymphoma cell lines." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249555.
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Lundblad, Katarina. "Studies on Tropical Palaeo-variation in Climate and Cosmic Ray Influx : Geochemical data from stalagmites collected in Tanzania and northern South Africa." Doctoral thesis, Stockholm : Department of Physical Geography and Quaternary Geology, Stockholm university, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-982.
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Reynders, Nadia. "Interface : altering architecture : transforming existing mono-functional buildings in the Pretoria CBD to adapt to changing social spatial conditions. The notion of ‘altering architecture’ aims to manipulate existing boundaries into INTERFACES to affect interior spaces and building skins as well extend into the urban context." Diss., University of Pretoria, 2010. http://hdl.handle.net/2263/30070.
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In a globalised world, influenced by social flux brought about by various factors¹, cities’ perimeters are subject to continuous change. More often than not, a city’s perimeter expands in the form of urban sprawl. Energy drains from the centre, leaving in its wake numerous vacant, degraded and underutilised structures. Radical interventions on an urban scale are often proposed to counter this degradation and transformation of such urban areas. These interventions² entail densification of the urban fabric, the insertion of additional structures and the creation of new precincts; a process which occurs over many years. By comparison, well-considered alterations to existing built fabric can be implemented quickly with smaller financial and ecological implications. Such alterations also include the adaptation of interior space to support a change in programme, and the possible improvement of a buildings interface with the street. The aim is to improve local social environments within the urban fabric and stimulate social influx. INTERFACE is about interventions to existing structures within the CBD of Pretoria. These interventions are limited to low-rise buildings (between two and five stories) designed specifically for mono-function. Over time, the programme and user profile of those buildings has changed, while the built fabric stagnated, with no active response to its context. Currently, such buildings do not participate in the creation of a living city – a city where interior spaces are supplemented by well designed outdoor spaces, thereby creating places that support and encourage social interaction. Buildings which have simply been taken over and used ad hoc, have not truly been adapted to their new programmes and as such, full exploitation of the space is not possible. Interior spaces can therefore play a determining role in the social motion³ of the city, but only if they address the transition between interior and exterior space, and the extension of such transition into the subsequent urban fabric. These interior and exterior spaces should be adaptable to current social needs of city dwellers and users in order to be deemed successful. Living cities require buildings to adapt and change in response to ever shifting social conditions in order to satisfy basic human desires and needs. It can thus be deduced that a building programme will more than likely change regularly. INTERFACE therefore focus on the creation of responsive interior space and works from the premise that structure and interior are implicitly linked. This thesis explores ‘permanent’ changes to existing structures; changes that will assist in creating responsive interior environments. Such environments should also accommodate both semi-permanent and temporary alterations, with minimal impact⁴ resulting from the implementation of each new programme. 1 Factors: Include change in political, social and economical circumstances. 2 Interventions: In Pretoria CBD, large interventions are proposed over long periods of time. They include strategies such as the Tshwane City Strategy (twenty year),Tshwane Inner City Development and Regeneration Strategy 2005 (ten year program) and City of Tshwane Integrated Development Plan 2009/2010 (five year). 3 Social motion: Interaction and attraction of civilians in a space 4 Impact: Refer to alterations to the permanent responsive structure as well as financial and ecological implications.Dissertation (MInt(Prof))--University of Pretoria, 2010.
Architecture
unrestricted
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Segato, Tommaso. "Time-series Database: progettazione e sviluppo di una libreria di supporto al tool Influx 2.0." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21555/.
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Nella tesi viene presentato il processo di progettazione e sviluppo di una libreria JavaScript come supporto ad InfluxDB v2.0. Il progetto è anticipato da una descrizione delle caratteristiche e usi delle serie temporali e time-series database, con una digressione sui TSDB e i loro utilizzi più comuni. Vengono anche presentate, in maniera approfondita, le caratteristiche di funzionamento e gli elementi propri di InfluxDB v2.0.
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Tolhurst, Gwen Rachel. "A study of cationic influx channels in the murine megakaryocyte : a model for platelet signalling." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614220.
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Gunnarsson, Urban. "Vegetation changes on Swedish mires : Effects of raised temperature and increased nitrogen and sulphur influx." Doctoral thesis, Uppsala : Acta Universitatis Uppsaliensis, 2000. http://catalogue.bnf.fr/ark:/12148/cb40007342x.
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Silva, Petterson Costa ConceiÃÃo. "Role of glutamine in the regulation of nitrate influx in cowpea roots exposed to salinity." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=16067.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoThere are many studies showing that the salinity may directly affect the nitrate uptake, from their osmotic effect, nature of the salt and its ionic composition. However, little is known about the mechanisms related to the salt ability to inhibit the nitrate acquisition indirectly. This study was carried with aim to induce inhibition of NO3- influx in cowpea roots of indirect form triggered by a negative feedback mechanism, caused by the increase in the pool of free amino acids in the tissue, induced by salt stress.For this, were done three isolated studies and continuous.The exogenous glutamine application promoted an increase in the free amino acids content.The presence of glutamine decreased significantly the nitrate acquisition.The free ammonium can also be listed as a key-compound in the role of nitrate influx regulation, since use of the MSX (Methionine sulfoximine) promoted the increase of NH4+ content and also reduced nitrate influx, but, in a lesser degree when compared to treatment with AZA (Azaserine). Salt stress caused a reduction in NO3- influx by decrease in the growth of plants induced by salt. The data indicated which this reduction in the influx is triggered by increase of amino acids content, mainly the glutamine, that is main likely compound to act as signal in the N-feedback regulation.
Existem muitos estudos mostrando que a salinidade pode afetar a absorÃÃo de nitrato de forma direta, a partir do seu efeito osmÃtico, da natureza do sal e de sua composiÃÃo iÃnica. Entretanto, pouco se sabe sobre os mecanismos relacionados com a capacidade do sal em inibir a aquisiÃÃo de nitrato de forma indireta. O presente estudo teve como objetivo induzir a inibiÃÃo do influxo de NO3- em raÃzes de feijÃo-caupà de forma indireta desencadeada por um mecanismo de feedback negativo, provocado pelo aumento no pool de aminoÃcidos livres no tecido, induzido por estresse salino. Para isso, foram realizados trÃs estudos isolados e contÃnuos. A aplicaÃÃo de glutamina exÃgena promoveu um aumento no conteÃdo de aminoÃcidos livres. A presenÃa de glutamina reduziu significativamente a aquisiÃÃo de nitrato. O amÃnio livre tambÃm pode ser listado como um composto-chave no papel da regulaÃÃo do influxo de nitrato, pois a utilizaÃÃo do MSO (Metionina sulfoximina) promoveu o aumento do conteÃdo de NH4+ e tambÃm reduziu o influxo de nitrato, porÃm em menor grau quando comparado ao o tratamento com AZA (Azaserina). O estresse salino causou uma reduÃÃo no influxo de NO3-, pela diminuiÃÃo no crescimento das plantas induzida pelo sal. Adicionalmente, estes dados indicaram que esta reduÃÃo no influxo està ligada ao aumento do teor de aminoÃcidos, principalmente a glutamina, que à o principal componente para atuar como sinal na regulaÃÃo por N-feedback.
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Laloi, Maryse. "Caractérisation de transporteurs (efflux du saccharose, influx de peptides) impliqués dans la distribution des assimilats." Poitiers, 1995. http://www.theses.fr/1995POIT2283.
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Par une approche biochimique realisee a poitiers nous avons caracterise l'efflux du saccharose a partir de vesicules de plasmalemme et par une approche de biologie moleculaire realisee a berlin, nous avons caracterise un transporteur d'oligopeptides. Le chargement du saccharose dans le complexe conducteur etant apoplastique chez de nombreuses plantes, le saccharose doit traverser la membrane des cellules de mesophylle avant d'etre charge dans le phloeme. Pour mieux comprendre le mecanisme de liberation du saccharose dans l'apoplaste, nous avons caracterise l'efflux de ce sucre a partir de vesicules de plasmalemme de feuilles de betterave sucriere (beta vulgaris) dans des conditions passives et energisees. L'etude en conditions passives a permis de mettre en evidence l'existence d'un transporteur different de celui de l'influx. En effet l'efflux est un phenomene saturable, sensible a differents inhibiteurs (n-ethylmaleimide, acide p-chloromercurybenzenesulfonique diethylpyrocarbonate) mais insensible a un serum anti-42 kda capable d'inhiber l'influx du saccharose dans des vesicules de plasmalemme. L'etude en conditions energisees a suggere l'existence de deux mecanismes possibles: un antiport proton/saccharose, l'efflux etant stimule par un gradient de ph normal (interieur alcalin) et dans ces conditions sensible a l'acide p-chloromercurybenzenesulfonique a la n-ethylmaleimide et au mersalyl. Un symport proton/saccharose, l'efflux etant stimule tres fortement par un gradient de ph inverse. L'antiport est le mecanisme qui vraisemblablement intervient in vivo. La complementation de mutants de levure a permis le clonage de plusieurs genes appartenant a differentes familles de transporteurs d'acides amines. Parmi eux, un gene ntr1 isole chez arabidopsis thaliana code pour une proteine membranaire ayant une tres faible activite de transport de l'histidine. La sequence d'acides amines de cette proteine est homologue a des sequences de transporteurs d'oligopeptides de differentes especes incluant arabidopsis. Un mutant de levure deficient en transport d'oligopeptides a ete construit et a permis de demontrer que ntr1 est un transporteur d'oligopeptides a haute affinite, responsable d'un transport actif, contre un gradient de concentration. Ce transporteur possede une tres large specificite et est exprime a un faible niveau dans les feuilles mais a un niveau beaucoup plus eleve dans les siliques en developpement. Son expression est restreinte a l'embryon ou elle est maximum au stade cur de l'embryogenese. Ntr1 joue donc un role dans l'approvisionnement en azote des embryons au cours de leur developpement
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Khawaja, Rabia Raheel. "Role of calcium influx through glutamate receptors in white matter brain injury and oligodendrocyte regeneration." Diss., Temple University Libraries, 2019. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/583654.
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Biomedical SciencesPh.D.
Calcium-influx through ionotropic glutamate receptors expressed on non-excitable cells, such as CNS glia, may regulate important cell events via intracellular signaling mechanisms. Oligodendrocytes and oligodendrocyte progenitors (OPCs), two glial populations supporting CNS myelination and myelin repair, express AMPA and NMDA receptors. Although calcium-influx through these receptors is thought to cause glutamate excitotoxicity to oligodendrocytes in CNS injuries, more recent studies suggest that AMPA or NMDA receptor-mediated synaptic transmission between neurons and OPCs plays a positive role in neuronal activity-dependent oligodendrocyte development and regeneration. Given the opposing roles of glutamate receptors in oligodendrocyte death and repair, the clinical relevance of these receptors in white matter injuries remain unclear. Another major challenge for exploring the role of these receptors in white matter injuries is that OPCs and neurons express a similar complement of AMPA and NMDA receptor subunits, which has complicated the interpretation of pharmacological manipulations and global genetic deletion approaches. To define the cell autonomous role of AMPA and NMDA receptor-mediated calcium signaling in oligodendroglia, I abolished the calcium influx through glutamate receptors using two different genetic approaches, and examined their impacts on oligodendrocyte development, injury-induced cell death, and regeneration. First, I employed a new mouse line which allows overexpression of GluA2, the calcium-impermeable AMPA receptor subunit, in a Cre activity-dependent manner. After crossing these mice with OPC- or oligodendrocyte-lineage-specific Cre mice, I applied hypoxic-ischemic injury to these multiple transgenic mice. Surprisingly, even though AMPA receptor-mediated calcium influx was blocked in OPCs, oligodendrogenesis or myelin integrity was not affected. However, GluA2 overexpression significantly promoted oligodendrocyte regeneration and OPC proliferation after injury, while the same manipulation in oligodendrocytes did not protect them from the initial cell loss. Moreover, GluA2 overexpression also stimulated transcriptional activities linked to myelinogenesis, even without injury. Second, I used conditional knockout mice for Grin1, the gene encoding an essential subunit of NMDA receptor complexes. As with GluA2 overexpressing mice, the removal of NMDA receptors from OPCs or all oligodendroglia did not significantly change normal oligodendrocyte development. However, the ablation of NMDA receptor in OPCs exacerbated oligodendrocyte loss by impairing new oligodendrogenesis in hypoxic-ischemic injury. These results suggest that neither AMPA receptors nor NMDA receptors mediate glutamate excitotoxicity in oligodendrocytes in neonatal hypoxic-ischemic injury. Instead, these receptors play distinct roles in post-injury oligodendrocyte development: AMPA receptor-mediated calcium suppresses oligodendrocyte regeneration, and NMDA receptor signaling supports oligodendrocyte regeneration after injury.
Temple University--Theses
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Hawley, Greer. "Diatoms : indicators of tidal influx in a hydraulically regulated estuary, Zandvlei, in the southern Cape." Bachelor's thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/26027.
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Estuarine systems are characterised by relatively high levels of salinity due to their connection with the sea. Zandvlei has been victim too much manipulation for the sake of flood prevention, recreation and water level regulation. One of the largest impacts on the system is the rubble weir placed at the mouth of the outlet channel that was built to maintain water levels in the drier summer months. There is evidence that the salinity in the estuary is declining, as the weir inhibits sufficient tidal ingress. Resultant consequences include encouraging the growth of alien invasive weeds, the decline of indigenous aquatic fauna and flora, and a shift in ecosystem functioning. Plans to increase the circulation of seawater have already been proved to be necessary, but the process needs to be monitored. Diatoms are used regularly in Europe to monitor water quality in terms of eutrophication and pollution. This study attempts to describe the change in diatom composition after the mouth has been manually opened, in terms of the influencing factors, namely salinity and temperature. The species response was found to be a shift in species dominance rather than a species turnover. Key indicator species were distinguished by the response to salinity. Diatoms can also be informative of the stability of the Vlei and therefore act as a valuable tool for monitoring purposes.
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Shailes, Sarah. "Regulation of calcium influx and reactive oxygen species production during infection of legumes by rhizobia." Thesis, University of East Anglia, 2014. https://ueaeprints.uea.ac.uk/48752/.
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Nod factor (NF) can induce two separate calcium responses in legume root hairs. Nuclear-associated calcium spiking is central to the symbiosis signalling (Sym) pathway, which is necessary for the activation of genes required for nodule formation and bacterial infection. In addition NF activates a tip-focused calcium influx, which is less-well studied but is thought to be involved in bacterial infection. NF also activates ROS transient production at the tip of root hair cells. In this thesis I used fluorescent probes (Ca2+-sensitive Cameleons YC2.1 and YC3.6 and the ROS-sensitive CM-H2DCFDA dye) to characterise the NF-induced calcium influx and ROS transient responses in Medicago truncatula. Along with being spatially and temporally co-incident, the responses require similar concentrations of NF to be activated, are inhibited by the NADPH oxidase inhibitor diphenyleneiodonium and are dependent on the NF receptor NFP but independent of the Sym pathway components DMI1 and DMI2. These results suggest the NF-induced calcium influx and ROS transient are part of a common signalling pathway during bacterial infection. ROP signalling is associated with ROS production and calcium influx during developmental root hair elongation. I assessed the role of ROPs during rhizobial infection in M. truncatula and found a ROP-activating protein, MtGAP1, was upregulated in root hairs during bacterial infection and is involved in normal root hair curling and infection thread development. Two pieces of evidence directly link ROP signalling with the NF-induced calcium influx: gap1 mutants were hypersensitive for induction of the calcium influx, and there was a reduction in the number of calcium influx responses in ROP9 RNAi knockdown lines. Drawing parallels between developmental root hair elongation and bacterial infection I propose a model for the regulation of ROP signalling by NF leading to root hair curling, the activation of the calcium influx and ROS transient, and infection thread formation.
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Mathenge, Christine W. "Effects of migrant influx, occupance and land acquisition on changing land tenure patterns in southwest Uganda." [Bloomington, Ind.] : Indiana University, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3332470.
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