Thesis(M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.

Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

The GINS complex (a heterotetramer of Sld5, Psf1, Psf2 and Psf3) is a highly conserved DNA replication factor required for the initiation and elongation of DNA replication. GINS is believed to associate with Cdc45 and MCM proteins on replicating DNA. The interaction between GINS and MCM is also conserved in archaea. In my thesis, I explore the subcellular localisation of the GINS complex in relation to the MCM proteins and sites of DNA replication by high-resolution confocal microscopy. For these studies, I generated and carefully validated purified rabbit polyclonal and mouse monoclonal antibodies; these show a specific staining pattern by immunohistochemistry, immunoblotting and immunofluorescence. At high-resolution, all GINS antibodies produced a focal nuclear pattern, similar to that seen for the MCMs. However, confusingly, colocalisation between GINS and MCMs and between the GINS subunits themselves is poor. Investigations are continuing to understand this conundrum. Given the value of MCM proteins as specific and sensitive markers for cancer screening, I investigated whether GINS subunits also have potential diagnostic value. Sld5 and Psf3 expression is restricted to the proliferative compartment in normal tissue, but is found in the majority of cells in a wide range of dysplastic and malignant tissues, including cervix, colon and bladder. In vitro studies of tissue culture cells and cell lysates incubated in urine suggest that Sld5 protein is more stable than Mcm2 in harsh extracellular environments. In an ongoing pilot clinical study of Sld5 protein as a potential biomarker, Sld5 is readily and specifically detectable in the cellular fraction of the samples from prostate and bladder cancer patients. Work is ongoing to evaluate Sld5 protein levels in the supernatant portion of those same urine samples as an easy-to-screen diagnostic/prognostic marker for male urogenital cancers. Owing to their stability, GINS proteins hold promise as independent or complementary markers to the MCM proteins for cancer screening in harsh extracellular environments such as urine.

La redistribution temporelle et spatiale des masses environnementales déforment la surface de la Terre. Ces déformations sont observables par des techniques de géodésie spatiale telles que le GNSS. Depuis que les produits d'orbite et d'horloge très précis de l'IGS sont disponibles, que des algorithmes sophistiqués ont été développés, l'iPPP a ouvert une nouvelle ère pour l'analyse du GNSS et pour son application dans les études géophysiques. Ce travail fait partie des premières études pour analyser les différents effets de surcharge, en utilisant des séries temporelles de positionnement, en particulier avec le logiciel GINS-PC et les nouveaux produits d'orbite et d'horloge REPRO2 du GRGS (GR2). Nous visons à exploiter les positions sub-diurnes d'iPPP pour étudier divers effets de déformation de la Terre à différentes échelles de temps: sub-diurne à saisonniers et annuels. Notre objectif est de contribuer à la validation des modèles géophysiques, à l'observation des différents phénomènes non-maréaux, mais aussi de présenter la performance du mode iPPP et du logiciel GINS-PC. Ce dernier est un outil puissant pour les applications géodynamiques, qui permet d'étudier l'influence des effets de surcharge sur l'interprétation géodésique des séries temporelles. Après un aperçu des principales déformations de la surface de la Terre, nous présentons les techniques de géodésie qui ont déjà démontré leur potentiel dans l'analyse de déformation, en particulier dans les études de déformation de surcharge. Nous présentons ensuite la technique de GNSS et le mode de traitement iPPP que nous utilisons pour l'analyse des données. Nous montrons ensuite les résultats de deux études régionales. La première analyse étudie l'influence des effets de surcharge sur la détermination des vitesses tectoniques dans la chaîne des Pyrénées à partir de campagnes GNSS espacées dans le temps. Le deuxième cas d'étude tente de suivre l'évolution spatiale et temporelle des déformations induites par un événement de tempête extrême, à savoir la tempête Xynthia qui a eu lieu en France en 2010. Cette étude tente également d'identifier la réponse dynamique de l'océan pour le système de basse pression atmosphérique se déplaçant rapidement en utilisant des séries temporelles sub-diurnes. Enfin, nous allons vers une étude globale qui pose les bases pour de futures recherches. / The temporal and spatial redistribution of the environmental masses deform the surface of the Earth. These deformations are observable by space geodetic techniques such as GNSS. Since highly accurate IGS satellite and clock data are available and sophisticated algorithms have been developped, the integer fixed ambiguity Precise Point Positioning (iPPP) method opened a new era for the Global Navigation Satellite System (GNSS) analysis and its application in geophysical studies. This work is among the first studies to investigate the different loading effects using iPPP time series, particularly using the GINS-PC software and the new, reprocessed REPRO2 orbit and clock products of GRGS (GR2). We aim to exploit the sub-daily iPPP time series to study various Earth deformation effects at different time scales, from sub-daily to seasonal and annual periods. Our goal is to contribute to the validation of geophysical models, to the observation of the various non-tidal phenomena, as well as the presentation of the performance of the iPPP mode and the GINS-PC package that is a powerful tool for geodynamical applications, and to investigate the influence of the loading effects on geodetic time series interpretation. After an overview of the main deformations of the Earth's surface, we present the geodetic techniques that already demonstrated their potential in deformation analysis, in particular in loading deformation studies. We then review the GNSS technique and the iPPP processing mode as it was our choice for the data analysis. We then demonstrate two regional studies. The first one investigates the influence of the loading effects on GNSS campaign to determine tectonic velocities in the Pyrenees mountain chain. The second case study attempts to track the spatial and temporal evolution of an extreme storm event, the Xynthia windstorm that occured in France, in 2010. This study also tries to identify the ocean's response to the fast moving low pressure system using sub-daily iPPP time series. Finally we go towards a global study which gives base for future research.

This study examines the waste of cotton gins as a potential alternative energy source, on account of its heat content, availability, and low emission rates. To confirm that this potential energy source meets minimum industrial fuel standards, this research has carried out an investigation of some important physical characteristics and toxic element analysis of cotton gin waste. Using cotton gin waste as fuel is an attractive solution to the problems of disposing of a surplus agricultural waste as well as supplementing fuel must meet both environmental emission standards and industrial fuel standards, the physical and chemical characteristics of cotton gin waste and its toxic element concentrations are important for its objective evaluation as a fuel. Constituent components, moisture contents, and ash contents of four separate parts of cotton gin waste were determined and evaluated closely following the American Society for Testing and Materials (ASTM) test methods. The three most toxic heavy metals, Arsenic (As), Chromium (Cr), and Lead (Pb), chosen for quantitative analysis were determined by using an inductively coupled plasma atomic emission spectrometry and a microwave oven sample digestion method.

No description available.

Agricultural operations across the United States are encountering difficulties complying with current air pollution regulations for particulate matter (PM). PM is currently regulated in terms of particle diameters less than or equal to a nominal 10 μm (PM10); however, current legislation is underway to regulate PM with diameters less than or equal to a nominal 2.5 μm (PM2.5). The goals of this research were to determine the biases and uncertainties associated with current PM10 and PM2.5 sampling methods and to determine the extent to which these errors may impact the determination of cotton gin emission factors. Ideally, PM samplers would produce an accurate measure of the pollutant indicator; for instance, a PM10 sampler would produce an accurate measure of PM less than or equal to 10 μm. However, samplers are not perfect and errors are introduced because of the established tolerances associated with sampler performance characteristics and the interaction of particle size and sampler performance characteristics. Results of this research indicated that a source emitting PM characterized by a mass median diameter (MMD) of 20 μm and a geometric standard deviation (GSD) of 1.5 could be forced to comply with a 3.2 and 14 times more stringent regulation of PM10 and PM2.5, respectively, than a source emitting PM characterized by a MMD of 10 μm and a GSD of 1.5. These estimates are based on both sources emitting the same concentrations of true PM or concentrations corresponding to the particle diameters less than the size of interest. Various methods were used to estimate the true PM10 and PM2.5 emission factors associated with cotton gin exhausts and the extent to which the sampler errors impacted the PM regulation. Results from this research indicated that current cotton gin emission factors could be over-estimated by about 40%. This over-estimation is a consequence of the relatively large PM associated with cotton gin exhausts. These PM sampling errors are contributing to the misappropriation of source emissions in State Implementation Plans, essentially forcing Air Pollution Regulatory Agencies to require additional controls on sources that may be incorrectly classified has high emitters.

The CMG (Cdc45, MCM, GINS) helicase is required for cellular proliferation and functions to unwind double-stranded DNA to allow the replication machinery to duplicate the genome. Cancer cells mismanage helicase activation through a variety of mechanisms, leading to the potential for the development of novel anti-cancer treatments. Mammalian cells load an excess of MCM complexes that act as reserves for new replication origins to be created when replication forks stall due to stress conditions, such as drug treatment. Targeting the helicase through inhibition of the MCM complex has sensitized cancer cells to drugs that inhibit DNA replication, such as aphidicolin and hydroxyurea. However, these drugs are not used in the clinical management of cancer. We hypothesized that the effectiveness of the clinically relevant drugs gemcitabine and 5-FU against pancreatic cancer cells, and oxaliplatin and etoposide against colorectal cells, could be increased through co-suppression of the MCM complex. The oncogene c-Myc also leads to the mismanagement of CMG helicases in part due to a non-transcriptional role in overactivating replication origins and causing DNA damage. We sought to elucidate the mechanism by which Myc causes overactivation of CMG helicases. Herein we demonstrate that co-suppression of reserve MCM complexes in pancreatic or colorectal cancer cell lines treated with clinically applicable chemotherapeutic compounds causes significant loss of proliferative capacity compared with cells containing the full complement of reserve MCMs. This is in part due to an inability to recover DNA replication following drug exposure, leading to an increase in apoptosis. Targeting of Myc to genomic sites induced large-scale decondensation of higher order chromatin that was required for CMG helicase assembly and activation at reserve MCM complexes. The physiological mediators of Myc, GCN5 and Tip60, are required for the chromatin unfolding and Cdc45 recruitment. We conclude that depletion of the reserve MCM complexes causes chemosensitization of multiple human tumor cell types to several chemotherapeutic drugs used in the clinical management of human cancer. This argues for the development and use of anti-MCM drugs in combination with chemotherapeutic compounds, which has the potential to increase the therapeutic index of existing clinical compounds. We have also identified a previously unknown role for Myc in normal cell cycle progression whereby DNA replication initiation is regulated through the assembly and activation of CMG helicases on Myc-mediated open chromatin regions. Our results also provide new mechanistic insight into Myc oncogenic transformation in which overstimulation of DNA replication could result in genomic instability and provide an explanation for Myc driven oncogenic transformation.