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Articles 1 - 11 of 11
Full-Text Articles in Life Sciences
Physiological Characterization Of Prochlorococcus Under Abiotic Stressors Temperature And Hydrogen Peroxide, Lanying Ma
Physiological Characterization Of Prochlorococcus Under Abiotic Stressors Temperature And Hydrogen Peroxide, Lanying Ma
Doctoral Dissertations
Cyanobacteria of the genus Prochlorococcus are the smallest and most abundant phytoplankters in the ocean. Temperature is a major influence on Prochlorococcus abundance and distribution in the ocean, but the physiological basis for this relationship is not well understood. In other microbes, lipid and fatty acid composition have been shown to be influenced by temperature, and temperature has also been proposed as a relevant factor for setting the elemental allocation in marine phytoplankton. In this study, we found that percentage of fatty acids unsaturation was negatively related with temperature in some Prochlorococcus strains, but this was not universal. Temperature had …
Bacterial Diversity And Function Within An Epigenic Cave System And Implications For Other Limestone Cave Systems, Kathleen Merritt Brannen-Donnelly
Bacterial Diversity And Function Within An Epigenic Cave System And Implications For Other Limestone Cave Systems, Kathleen Merritt Brannen-Donnelly
Doctoral Dissertations
There are approximately 48,000 known cave systems in the United States of America, with caves formed in carbonate karst terrains being the most common. Epigenic systems develop from the downward flow of meteoric water through carbonate bedrock and the solutional enlargement of interconnected subsurface conduits. Despite carbonate karst aquifers being globally extensive and important drinking water sources, microbial diversity and function are poorly understood compared to other Earth environments. After several decades of research, studies have shown that microorganisms in caves affect water quality, rates of carbonate dissolution and precipitation, and ecosystem nutrition through organic matter cycling. However, limited prior …
Epidemiology Of Select Species Of Filarial Nematodes In Free-Ranging Moose (Alces Alces) Of North America, Caroline Mae Grunenwald
Epidemiology Of Select Species Of Filarial Nematodes In Free-Ranging Moose (Alces Alces) Of North America, Caroline Mae Grunenwald
Doctoral Dissertations
North American moose (Alces alces) are a culturally and economically valued species. Recent population declines raise concern for the survivability of this natural resource. The Minnesota population has experienced the most dramatic decline, with a 60% loss in total numbers since 2006. Nematode parasites, particularly some species of filarids, are important pathogens of moose and could be contributing to morbidity and mortality. This study investigates the eco-epidemiology of two filarial parasites of moose: Rumenfilaria andersoni and Elaeophora schneideri. By surveying cervid species from six U.S. states, we discovered R. andersoni was present in moose from all sample locations …
Energetic Limitations Of Thermophilic Methanogens And Thiosulfate Reducers In The Subsurface Biosphere At Deep-Sea Hydrothermal Vents, Lucy C. Stewart
Energetic Limitations Of Thermophilic Methanogens And Thiosulfate Reducers In The Subsurface Biosphere At Deep-Sea Hydrothermal Vents, Lucy C. Stewart
Doctoral Dissertations
This dissertation examined the substrate and energetic limitations of hydrogenotrophic thermophiles from deep-sea hydrothermal vents. Thermophilic and hyperthermophilic organisms in diffuse hydrothermal venting are thought to represent a hot subsurface biosphere associated with deep-sea hydrothermal vents, where primary production is dominated by hydrogenotrophy rather than sulfide oxidation as at the vent/seawater interface of hydrothermal sulfide chimneys. Methanogens and sulfur-reducers are known to compete for hydrogen in mesophilic, freshwater systems, and likely do so in deep-sea hydrothermal vent environments as well. However, the exact size and biomass of the subsurface biosphere is difficult to determine through direct sampling. Firstly, the distribution …
Engineering Novel Detection And Treatment Strategies For Bacterial Therapy Of Cancer, Jan T. Panteli
Engineering Novel Detection And Treatment Strategies For Bacterial Therapy Of Cancer, Jan T. Panteli
Doctoral Dissertations
Finding and treating cancer is difficult due to limited sensitivity and specificity of current detection and treatment strategies. Many chemotherapeutic drugs are small molecules that are limited by diffusion, making it difficult to reach cancer sites requiring high doses that lead to systemic toxicity and off-target effects. Tomographic detection techniques, like PET, MRI and CT, are good at identifying macroscopic lesions in the body but are limited in their ability to detect microscopic lesions. Biomarker detection strategies are extremely sensitive and able to identify ng/ml concentrations of protein, but are poor at discriminating between healthy and disease state levels due …
The Role Of Phosphatidylserine And Phosphatidylethanolamine In Candida Albicans Virulence, Sarah Elizabeth Davis
The Role Of Phosphatidylserine And Phosphatidylethanolamine In Candida Albicans Virulence, Sarah Elizabeth Davis
Doctoral Dissertations
In hospitalized patients with neutropenia, Candida albicans is the fourth leading cause of systemic bloodstream infections, which have a mortality rate of approximately 30 %. The phosphatidylserine synthase enzyme of C. albicans, Cho1p, appears to be a good drug target as a mutant lacking this enzyme (the cho1Δ/Δ [null mutant]) is avirulent in animal models of Candida infections and this enzyme is not conserved in humans. We discovered that the loss of phosphatidylserine (PS) synthesis affects C. albicans' expression of the Als3p adhesin, a virulence protein, and loss of PS synthesis also compromises the cell wall, causing increased …
Cmv Chemokines And Co-Infection: A Dissemination Plot That Peptides Can Foil, Pranay Dogra
Cmv Chemokines And Co-Infection: A Dissemination Plot That Peptides Can Foil, Pranay Dogra
Doctoral Dissertations
Human Cytomegalovirus (HCMV) is the leading cause of both non-hereditary mental retardation and hearing loss, and CMV infection/reactivation causes serious complications in transplant and immune compromised patients. Due to these issues, development of a CMV vaccine and/or therapeutics is required. To achieve this goal, it is necessary to gain a better understanding of CMV pathogenesis. Because of its coevolution with humans, HCMV has evolved genes with homology to human immune modulatory genes. Several of these genes help CMV establish a successful and lifelong infection within the host. An example is the viral CXC chemokine homolog UL146 gene (vCXCL-1). UL146 varies …
Genetic Diversity, Population Structure, And Evolution Of Virulence In Toxoplasma Gondii, Elliot Keats Cullen Shwab
Genetic Diversity, Population Structure, And Evolution Of Virulence In Toxoplasma Gondii, Elliot Keats Cullen Shwab
Doctoral Dissertations
Toxoplasma gondii is among the most widespread eukaryotic pathogens known. It chronically infects approximately one third of the world’s human population and has been isolated from an extremely diverse array of globally distributed mammals and birds. Understanding the structure of the worldwide T. gondii population enhances our understanding of the factors that have shaped that structure and led to the proliferation of one of the most evolutionarily successful pathogens on Earth. Herein we collate genotypic data from global isolates, demonstrating that T. gondii possesses a unique population structure in which only a small number of genotypes dominate throughout the northern …
Elucidating The Impact Of Roseophage On Roseobacter Metabolism And Marine Nutrient Cycles, Nana Yaw Darko Ankrah
Elucidating The Impact Of Roseophage On Roseobacter Metabolism And Marine Nutrient Cycles, Nana Yaw Darko Ankrah
Doctoral Dissertations
As the most abundant biological entities in marine environments, viruses are an important component of marine food webs. The activity of viruses contributes significantly to the mortality of marine microorganisms, ultimately influencing biological function and chemical composition of aquatic systems by impacting species composition and flow of carbon, nitrogen and other nutrients. Despite the growing recognition that viral activity contributes to marine biogeochemical cycles, the extent to which virus infection reshapes host metabolism and the effect of this alteration on the composition of host lysate remains poorly understood. Additionally, the degree to which natural bacterioplankton communities metabolise the released lysate …
Thermal Inactivation Of Shiga Toxin-Producing Escherichia Coli In Foods, Malcond David Valladares
Thermal Inactivation Of Shiga Toxin-Producing Escherichia Coli In Foods, Malcond David Valladares
Doctoral Dissertations
Emerging non-O157 Shiga toxin-producing Escherichia coli (STEC) were recently added to the zero tolerance policy by the USDA-FSIS. Therefore, the precise characterization of their thermal inactivation kinetics in different foods and the effect of stress on thermal inactivation are needed. This research aimed at determining the heat inactivation kinetics of non-O157 and O157 STECs in buffer and model food matrices and the effects of DnaK levels on thermal resistance after acid and heat-shock. Thermal inactivation was carried out in either in 2-ml glass vials or nylon vacuum-sealed bags for buffer and food (spinach, ground-beef, turkey deli-meat, pasta) samples, respectively. Vials …
Mechanisms For Extracellular Electron Exchange By Geobacter Species, Jessica A. Smith
Mechanisms For Extracellular Electron Exchange By Geobacter Species, Jessica A. Smith
Doctoral Dissertations
Understanding the mechanisms for microbial extracellular electron exchange are of interest because these processes play an important role in the biogeochemical cycles of both modern and ancient environments, development of bioenergy strategies, as well as for bioremediation applications. Only a handful of microorganisms are capable of extracellular electron exchange, one of the most thoroughly studied being the Geobacter species. Geobacter species are often the predominant Fe(III) reducing microorganisms in many soils and sediments, can exchange electrons directly via interspecies electron transfer, and can both donate or accept electrons with a wide variety of extracellular substrates including the electrode of a …