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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.
291

Functional characterization of two divergently transcribed genes: ptrA, encoding a LysR-type transcriptional regulator, and scd, encoding a short-chain dehydrogenase in Pseudomonas chlororaphis PA23

Klaponski, Natasha 10 April 2014 (has links)
Pseudomonas chlororaphis PA23 inhibits several root pathogens in both the greenhouse and field. A LysR-type transcriptional regulator (LTTR) called PtrA (Pseudomonas transcriptional regulator A) that is essential for Sclerotinia sclerotiorum antifungal activity was discovered through transposon mutagenesis. P. chlororaphis PA23 produces the antibiotics phenazine 1-carboxylic acid, 2-hydroxyphenazine and pyrrolnitrin, and several additional products that contribute to biocontrol. Phenotypic assays and proteomic analysis have revealed that production of these secondary metabolites are markedly reduced in a ptrA mutant. Most LTTRs regulate genes that are upstream of and divergently transcribed from the LTTR locus. A short chain dehydrogenase (scd) gene lies immediately upstream of ptrA in the opposite orientation. Characterization of an scd mutant, however, has revealed no significant changes in antifungal activity compared to wild-type PA23. Gene expression analysis of the ptrA mutant indicates that ptrA may exert its regulatory effects through the Gac-Rsm network, and may be controlling expression of the scd gene. Collectively these findings indicate that PtrA is an essential regulator of PA23 biocontrol and is connected to other regulators involved in fungal antagonism.
292

Enskilda avlopp i Nordmalings kommun : Status, skyddsnivåer och teknikval i olika jordartsområden

Engström, Linda January 2014 (has links)
The purpose of this study was to describe a) the status of the household sewage systems in the municipality of Nordmaling, b) to suggest areas in which a higher level of protection would be required and c) to investigate which type of technological choice was appropriate for which type of soil. A survey was used to investigate the status of the household sewage systems. The status was judged mainly on the age and treatment of water. Protected areas, the ecological status and data for phosphorus and nitrogen were used to locate areas in need of a higher protection. Map data from the Geological Survey of Sweden was used to identify common soil types in Nordmaling. Subsequently, the map was complemented and verified with a field investigation. In a next step, characteristics of the soil types were compared to the requirements of four different sewage treatment technologies; infiltration, constructed infiltration, incinerator toilets and household sewage plants. The study shows that the household sewage systems in Nordmaling are in general not in a good condition. Almost 70 % of the sewage systems are older than 20 years and their function is likely not sufficient. The study suggests that the following areas should be included in the list of objects with high protection: Lögde- and Öre river, Kronören, Järnäs peninsula, waters with an ecological status below “good” and the protected water resources. Except for infiltration, all sewage treatment technologies were assumed to give appropriate results for all soil types.
293

Type Inferencing and MATLAB to Modelica Translation

Mohammad, Jahanzeb January 2014 (has links)
Matlab is a proprietary, interactive, dynamically-typed language for technical computing. It is widely used for prototyping algorithms and applications of scientific computations. Since it is a dynamically typed language, the execution of programs has to be analyzed and interpreted which results in lower computational performance. In order to increase the performance and integrate with Modelica applications it is useful to be able to translate Matlab programs to statically typed Modelica programs. This project presents the design and implementation of Matlab to Modelica translator. The Lexical and Syntax analysis is done with the help of the OMCCp (OpenModelica Compiler Compiler parser generator) tool which generates the Matlab AST, which is later used by the translator for generating readable and reusable Modelica code.
294

Genome-environment Interactions in Type 1 Diabetes

Markle, Janet 20 June 2014 (has links)
This project aims to integrate knowledge of genetic susceptibility, immune cell function, and environmental modifiers in determining risk for type 1 diabetes (T1D) in the non-obese diabetic (NOD) mouse model. Similar to human T1D, disease risk in the NOD mouse is polygenic and has been mapped to multiple Idd loci. We have fine-mapped the Idd4.1 locus and identified Nlrp1b as its candidate gene. We report an alternatively spliced isoform in the diabetes-resistant Nrlp1b allele, resulting in a truncated NLRP1b protein that is unable to activate release of IL-1β. In another aspect of this project, we have characterized the critical contribution to T1D pathogenesis by γδ T cells. We report that CD27- γδT cells infiltrate islets of pre-diabetic NOD mice. Adoptive transfer of T1D to lymphocyte-deficient NOD.SCID recipients was potentiated when CD27- γδ T cells were transferred, compared to transfer of αβ T cells alone. Antibody-mediated blockade of IL-17 prevented T1D transfer in this setting. Moreover, introgression of genetic Tcrd deficiency onto the NOD background provided robust T1D protection. Finally, we report novel relationships between the gut microbiome, host sex hormones and metabolism, and T1D pathogenesis in the NOD mouse. Using germ-free, specific pathogen free, and microbiome-transplanted NOD mice, we show that colonization by commensal microbes elevated serum testosterone and protected NOD males from T1D. Transfer of gut microbiota from adult males to immature females altered the recipients’ microbiota, resulting in elevated testosterone and metabolomic changes, reduced islet inflammation and autoantibody production, and endowed robust T1D protection. Collectively, the data presented in this thesis describe a novel genetic lesion involved in T1D risk and its immunological consequences, demonstrate a potent role for IL-17-producing γδ T cells in NOD mouse model, and uncover a novel relationship between the gut microbiome, host hormonal and metabolic phenotypes, and autoimmunity risk.
295

Investigating the mechanisms and effectiveness of common buckwheat (Fagopyrum esculentum Moenech) for acute modulation of glycemia

Stringer, Danielle Marie January 2010 (has links)
Type 2 diabetes (T2DM) is a chronic disease characterized by cellular insulin resistance and consequent disturbances in glucose metabolism. Long-term consumption of buckwheat has been previously shown to improve glycemia in individuals with T2DM; however, the underlying mechanisms as well as the contribution of improved acute glycemic responses have not been fully characterized. The current study used cell culture and clinical studies to investigate the mechanisms and effectiveness of common buckwheat for acute modulation of glucose metabolism and glycemia. Glucose uptake was inhibited in H4IIE cells treated with a buckwheat extract (BWE), an effect attributed to the actions of an unknown compound(s). Reduced glucose uptake and transepithelial glucose transport was also present in Caco2 colorectal adenocarcinoma cells and monolayers. The mechanism behind inhibited glucose uptake did not involve modulation of several signaling pathways regulating glucose metabolism, including p38 MAPK, p42/44 ERK, PI3Kγ, PKC, PKA, mTOR and AMPK. Interestingly, BWE treatment was associated with other effects on glucose metabolism, including elevated glucose production and levels of gluconeogenic enzymes. However, these effects were not mediated through the classical pathway of CREB activation involving cyclic AMP and PKA. In a blinded, reference product-controlled study, consumption of a cracker product made from whole grain common buckwheat flour containing 50 grams of available carbohydrate was not associated with changes in post-prandial glucose or insulin concentrations in both healthy individuals and those with diet-controlled T2DM. However, consumption of buckwheat crackers was associated with changes in selected gastrointestinal satiety hormones. Interestingly, several significant correlations observed between fasting concentrations and the overall post-prandial response of these hormones were affected by T2DM. In conclusion, glucose-lowering effects of common buckwheat are not due to the actions of known bioactive compounds, and may involve direct inhibition of facilitative transporters by a novel compound. Although a buckwheat food product did not reduce post-prandial glycemia, identifying the compound responsible for inhibited glucose uptake will allow development of food products enriched with this compound, and may represent a more effective dietary approach to managing glycemia.
296

Genome-environment Interactions in Type 1 Diabetes

Markle, Janet 20 June 2014 (has links)
This project aims to integrate knowledge of genetic susceptibility, immune cell function, and environmental modifiers in determining risk for type 1 diabetes (T1D) in the non-obese diabetic (NOD) mouse model. Similar to human T1D, disease risk in the NOD mouse is polygenic and has been mapped to multiple Idd loci. We have fine-mapped the Idd4.1 locus and identified Nlrp1b as its candidate gene. We report an alternatively spliced isoform in the diabetes-resistant Nrlp1b allele, resulting in a truncated NLRP1b protein that is unable to activate release of IL-1β. In another aspect of this project, we have characterized the critical contribution to T1D pathogenesis by γδ T cells. We report that CD27- γδT cells infiltrate islets of pre-diabetic NOD mice. Adoptive transfer of T1D to lymphocyte-deficient NOD.SCID recipients was potentiated when CD27- γδ T cells were transferred, compared to transfer of αβ T cells alone. Antibody-mediated blockade of IL-17 prevented T1D transfer in this setting. Moreover, introgression of genetic Tcrd deficiency onto the NOD background provided robust T1D protection. Finally, we report novel relationships between the gut microbiome, host sex hormones and metabolism, and T1D pathogenesis in the NOD mouse. Using germ-free, specific pathogen free, and microbiome-transplanted NOD mice, we show that colonization by commensal microbes elevated serum testosterone and protected NOD males from T1D. Transfer of gut microbiota from adult males to immature females altered the recipients’ microbiota, resulting in elevated testosterone and metabolomic changes, reduced islet inflammation and autoantibody production, and endowed robust T1D protection. Collectively, the data presented in this thesis describe a novel genetic lesion involved in T1D risk and its immunological consequences, demonstrate a potent role for IL-17-producing γδ T cells in NOD mouse model, and uncover a novel relationship between the gut microbiome, host hormonal and metabolic phenotypes, and autoimmunity risk.
297

Relapse of orthodontically corrected deep bites in accordance with growth pattern

Pollard, Derek 15 September 2011 (has links)
OBJECTIVES: (1) Compare the relapse of corrected deep bites in three groups of patients separated by facial type (2) Determine the associations of various parameters influencing deep bite relapse. METHODS: 60 patients treated at the University of Washington were included, all with initial overbites >50%. Patients were grouped according to initial Y-axis, MPA, and LFH values. Data was collected from casts and cephalometric radiographs at three time points: pre-treatment, post-treatment, and ten years post-retention. RESULTS: Dolicocephalic subjects showed the least amount of deep bite relapse (0.1 ± 1.1 mm), while brachycephalic (1.2 ± 0.9 mm) and mesocephalic (1.4 ± 1.3 mm) subjects experienced significant relapse (p < 0.05). Intergroup comparisons revealed that the brachycephalic group had significantly more post-retention change in overbite, N-ANS, interincisal angle, and L1-MP than the dolicocephalic group (p<0.05). CONCLUSIONS: Orthodontists should consider overcorrection of overbite in brachycephalic and mesocephalic patients presenting with overbites >50%.
298

Type-II superconductors in high magnetic fields

Bruun, Georg Morten January 1998 (has links)
Superconductivity in high magnetic fields has attracted considerable atten- tion in recent years. The topic is important both for our fundamental un- derstanding of superfluids and for numerous practical applications. In this thesis, we consider several effects originating from the interplay between the Landau level structure of the normal state quasiparticle spectrum, and the tendency of the quasiparticles to form Cooper pairs below the critical tem- perature. A formalism designed to describe extreme type-II superconductors close to the upper critical field H<sub>c2</sub> is developed. The theory which utilizes the selection rules coming from the symmetry properties of the vortex lattice, simplifies the algebra describing a superconductor in the mixed state signifi- cantly. We are, on the mean field level, able to include the quantizing effects of the magnetic field on the electron motion exactly. A main achievement is the exact calculation of the expansion coefficients giving the grand canonical potential of a superconductor in terms of a power series in the size of the or- der parameter. The result is an expression for the grand canonical potential in terms of a polynomial in a finite set of variables close to H<sub>c2</sub>. Using this formalism, a theory for the experimentally observed damped de Haas-van Alphen (dHvA) oscillations in the mixed state of a 2-dimensional (2D) superconductor is presented. The theory is compared with numerical results and the agreement is found to be good. A simple physical interpreta- tion of the damping is provided. The dependence of the damping on a finite Zeeman term, temperature, and the magnetic field is considered. A compar- ison of the theory with experimental data for the quasi-2D superconductor K-(ET)<sub>2</sub>Cu(NCS)<sub>2</sub> yields good agreement. The attenuation of a longitudinal sound wave in the mixed state is then calculated. In analogy with the dHvA effect, we predict that there should be damped oscillations in the sound attenuation in the mixed state as the exter- nal magnetic field is varied. Furthermore, the dependence of the oscillations on the sound frequency and temperature is shown to yield information on the low lying quasiparticle spectrum. Especially, the presense of gapless excita- tions due to the magnetic field makes the attenuation qualitatively different as compared to the attenuation in the Meissner state. Some formal convergence properties of the Gor'kov theory for type-II su- perconductors close to H<sub>c2</sub> are derived. We show that the theory is essentially a high temperature expansion; the convergence radius of the Gor'kov series is proportional to k<sub>B</sub>T when there is a Landau level at the chemical potential.
299

Biochemical and biophysical characterisation of the domain structure of the HsdS subunit of EcoR124I

Smith, Melanie Anne January 2000 (has links)
No description available.
300

Type III Secreted Effectors as Molecular Probes of Eukaryotic Systems

Lee, Amy Huei-Yi 28 February 2013 (has links)
Successful bacterial pathogens manipulate crucial intracellular host processes as a virulence strategy. One particular potent mechanism utilized by bacterial phytopathogens is to inject virulence factors (effectors) directly into the host cell. While many effectors have been identified and shown to suppress plant immune responses, very few have well-characterized enzymatic activities or host targets. To overcome the challenges of functional analysis of effectors, I designed two heterologous screens to characterize effector proteins of the bacterial phytopathogen Pseudomonas syringae. Specifically, my objective was to identify those P. syringae effectors that target evolutionarily conserved host proteins or processes and to subsequently elucidate the molecular mechanisms of these effectors. The first heterologous screen that I performed was to utilize tandem-affinity-purification (TAP)-tagged effectors in human cells to identify potential interacting host proteins. The second heterologous screen iii utilized a high-throughput genomics approach in yeast, known as the pathogenic genetic array (PGA), to characterize P. syringae effectors. Using the first heterologous approach, I have identified HopZ1a as the first bacterial phytopathogen effector that binds tubulin. I have shown that HopZ1a is an acetyltransferase activated by the eukaryotic co-factor, phytic acid. In vitro, activated HopZ1a acetylates itself and tubulin. In Arabidopsis thaliana, activated HopZ1a causes microtubule destruction, disrupts the secretory pathway and suppresses cell wall-mediated defense. The acetyltransferase activity of HopZ1a is dependent on the conserved catalytic cysteine residue (C216) and a conserved lysine residue (K289). Using the second heterologous screen in yeast, I have shown that HopZ1a may target the mitogen-activated protein kinase (MAPK) signaling cascades. Together, my work has identified novel eukaryotic targets and elucidated the virulence functions of HopZ1a.

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