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Articles 1 - 26 of 26
Full-Text Articles in Life Sciences
Stream-Associated Amphibian Habitat Assessment In The Portland-Vancouver Metropolitan Region, Andrew Evans Dietrich
Stream-Associated Amphibian Habitat Assessment In The Portland-Vancouver Metropolitan Region, Andrew Evans Dietrich
Dissertations and Theses
This study assessed the influence of landscape development on stream-associated amphibians in forested riparian areas within the Portland-Vancouver metropolitan region. Human alteration of landscapes may dramatically affect the ecology of neighboring aquatic systems. It was hypothesized that lotic amphibians would be negatively associated with greater amounts of landscape development and positively associated with forested area within the surrounding watershed. Thirty-seven 1st-3rd order streams were sampled between June 21st and September 21st in 2011. Streams potentially providing adequate habitat for stream-obligate amphibians were randomly selected. Amphibians were surveyed along 30-meter stream transects using an active-cover search (ACS). Environmental variables associated with …
Site Selection By Migratory Shorebirds In Oregon Estuaries Over Broad And Fine Spatial Scales, Aileen Kilpatrick Miller
Site Selection By Migratory Shorebirds In Oregon Estuaries Over Broad And Fine Spatial Scales, Aileen Kilpatrick Miller
Dissertations and Theses
Many migratory shorebirds rely on estuaries as stop-over sites to refuel during migration, and the loss of stop-over sites is a primary threat to shorebird populations on the West Coast of the United States (e.g. Calidris alpina pacifica, C. mauri). Conservation and research has focused on the largest of these sites; however, smaller estuaries also host thousands of migratory shorebirds. Furthermore, the reasons for site selection are largely unknown. Estuarine inter-tidal microhabitats are non-uniform and both abiotic and biotic factors may serve as predictors of whether an abundance of shorebirds will use a site. I investigated shorebird site selection on …
Aging, Stem Cells And The Cancer Stem Cell Hypothesis, Dave Comstock
Aging, Stem Cells And The Cancer Stem Cell Hypothesis, Dave Comstock
Dissertations and Theses
No abstract provided.
The Molecular And Genetic Characterization Of L(3)Hem2 And L(3)Hem1, Putative Novel Alleles Of The Neurogenic Gene, Neuralized, Maria A. Otazo
The Molecular And Genetic Characterization Of L(3)Hem2 And L(3)Hem1, Putative Novel Alleles Of The Neurogenic Gene, Neuralized, Maria A. Otazo
Dissertations and Theses
No abstract provided.
Where Is The Rain-On-Snow Zone In The West-Central Washington Cascades?: Monte Carlo Simulation Of Large Storms In The Northwest, Matthew John Brunengo
Where Is The Rain-On-Snow Zone In The West-Central Washington Cascades?: Monte Carlo Simulation Of Large Storms In The Northwest, Matthew John Brunengo
Dissertations and Theses
Rain-on-snow (ROS) occurs when warm, wet air moves into latitudes and/or elevations having vulnerable snowpacks, where it can alter water inputs to infiltration, runoff and erosion. The Pacific Northwest is particularly susceptible: winter storms off the Pacific cause locally heavy rain plus snowmelt almost annually, and disastrous flooding and landsliding intermittently. In maritime mountainous terrain, the effects seem more likely and hydrologically important where warm rains and seasonal snowpacks are liable to coincide, in middle elevations. Several questions arise: (1) In the PNW, does ROS affect the long-term frequency and magnitude of water delivery to the ground, versus total precipitation …
Role Of Glia Subsets In Neurodegeneration And Life Span Reduction; Gain-Of-Function Phenotypes Following Glia Specific Overexpression Of Rap/Fzr, An Activator Of The Anaphase-Promoting Complex, Amandeep Kaur
Dissertations and Theses
No abstract provided.
Φ 6 Polymerase Conformation; Rna Packaging Portal Stability., Elena Futerman
Φ 6 Polymerase Conformation; Rna Packaging Portal Stability., Elena Futerman
Dissertations and Theses
No abstract provided.
Glia-Mediated Neurodegeneration In The Drosophila Melanogaster Cns, Ivan J. Santiago
Glia-Mediated Neurodegeneration In The Drosophila Melanogaster Cns, Ivan J. Santiago
Dissertations and Theses
No abstract provided.
Death- Associated Protein Kinase (Dapk); A Possible Modulator Of Neurodegeneration In A Caenorhabditis Elegans Model Of Excittotoxicity, John Smith Del Rosario
Death- Associated Protein Kinase (Dapk); A Possible Modulator Of Neurodegeneration In A Caenorhabditis Elegans Model Of Excittotoxicity, John Smith Del Rosario
Dissertations and Theses
No abstract provided.
Morphological And Neuroanatomical Changes Associated With The Induction Of Neurodegeneration And Life Span Reduction In Drosophila Melanogaster By Glia Targeted Expression Of Cdh1/Rap/Fzr, An Activator Of The Anaphase Promoting Complex, Israel Nnah
Dissertations and Theses
"The retina aberrant in pattern (rap) gene encodes the Fizzy-related protein (Fzr), an activator of the E3 ubiquitin ligase complex: the Anaphase Promoting Complex/Cyclosome (APC/C). APC/C facilitates the cell cycle stage-specific degradation of cyclins and other mitotic regulators, resulting in the inactivation of Cdk (Cyclin Dependent Kinase) complexes, thus promoting completion of mitosis. Previous studies from our laboratory have shown that Rap/Fzr (the Drosophila homolog of the mammalian Cdh1) regulates glia differentiation and promotes neuron formation. Recent studies have shown that the glia specific over expression of Rap/Fzr causes progressive neurodegeneration and life span reduction preceded by temperature sensitive paralysis, …
Post-Occupancy Evaluation At The Zoo: Behavioral And Hormonal Indicators Of Welfare In Orangutans (Pongo Pygmaeus Abelii), Leigha Tingey
Post-Occupancy Evaluation At The Zoo: Behavioral And Hormonal Indicators Of Welfare In Orangutans (Pongo Pygmaeus Abelii), Leigha Tingey
Dissertations and Theses
An increased understanding of species-specific behavioral needs has lead zoos to focus on providing more naturalistic and stimulating environments. Scientific assessments of how changes in habitat affect animal behavior are necessary in improving overall animal welfare. This study examined the move of three orangutans housed at the Oregon Zoo into a new and innovative exhibit. Post-occupancy evaluation (POE), which offers systematic information regarding the success or failure of the built environment (Maple & Finlay, 1987), was utilized to effectively evaluate the results of the move. The collection of behavioral data and adrenal activity monitoring through collection of non-invasive saliva, urine …
Effects Of Reactive Oxygen Species On Life History Traits Of Caenorhabditis Elegans, Samson William Smith
Effects Of Reactive Oxygen Species On Life History Traits Of Caenorhabditis Elegans, Samson William Smith
Dissertations and Theses
Evolutionary life history theory predicts that tradeoffs among fitness-related phenotypes will occur as a result of resource limitations and/or physiological constraints. Such tradeoffs are defined as the cost(s) incurred on one component of fitness (e.g., reproduction) by the increased expression of another fitness-related trait (e.g., longevity). Only recently have researchers begun to investigate the mechanistic bases of life history tradeoffs. A recent proposal is that reactive oxygen species (ROS) have a central role in shaping life history traits and tradeoffs. Research on disparate animal taxa has highlighted strong correlations between oxidative stress resistance and fitness-related life history traits, for example. …
The Role Of Nucleotide Excision Repair In Restoring Replication Following Uv-Induced Damage In Escherichia Coli, Kelley Nicole Newton
The Role Of Nucleotide Excision Repair In Restoring Replication Following Uv-Induced Damage In Escherichia Coli, Kelley Nicole Newton
Dissertations and Theses
Following low levels of UV exposure, Escherichia coli cells deficient in nucleotide excision repair recover and synthesize DNA at near wild type levels, an observation that formed the basis of the post replication recombination repair model. In this study, we characterized the DNA synthesis that occurs following UV-irradiation in the absence of nucleotide excision repair and show that although this synthesis resumes at near wild type levels, it is coincident with a high degree of cell death. We confirm that the replication occurring under these conditions involves extensive levels of strand exchange. However, cells undergoing this form of replication accumulate …
The Effects Of Hypoxia And Temperature On Developing Embryos Of The Annual Killifish Austrofundulus Limnaeus, Skye N. Anderson
The Effects Of Hypoxia And Temperature On Developing Embryos Of The Annual Killifish Austrofundulus Limnaeus, Skye N. Anderson
Dissertations and Theses
Little is known about the physiology or biochemistry of hypoxia (reduced levels of oxygen) tolerance during development in vertebrate embryos. In most species, relatively brief bouts of severe hypoxia are lethal or teratogenic. An exception to such hypoxia intolerance is the annual killifish Austrofundulus limnaeus, in which populations persist in hypoxic environments. This species inhabits seasonal ponds in Venezuela, surviving through the dry season in the form of diapausing embryos. Embedded in the pond sediment, embryos of A. limnaeus are routinely exposed to hypoxia and anoxia (lack of oxygen) as part of their normal development. Here, we exposed embryos to …
Spontaneous Cooperative Assembly Of Replicative Catalytic Rna Systems, Nilesh Vaidya
Spontaneous Cooperative Assembly Of Replicative Catalytic Rna Systems, Nilesh Vaidya
Dissertations and Theses
The RNA World hypothesis proposes a period of time during the origins of life in which RNA molecules were the only source of both genotypes and phenotypes. Although a vast amount of evidence has been obtained in support of this hypothesis, a few critical demonstrations are lacking. A most crucial one is a demonstration of self-replication of RNA molecule from prebiotic soup. Previously in the Lehman laboratory, it has been demonstrated that a 198-nucleotide molecule derived from the Azoarcus group I intron can self-assemble from up to four fragments of RNA via recombination. Furthermore, the covalent full-length molecules are catalytically …
Engaging Community Food Systems Through Learning Garden Programs: Oregon Food Bank's Seed To Supper Program, Denissia Elizabeth Withers
Engaging Community Food Systems Through Learning Garden Programs: Oregon Food Bank's Seed To Supper Program, Denissia Elizabeth Withers
Dissertations and Theses
The purpose of this study was to discover whether learning garden programs increase access to locally grown foods and successfully empower and include food insecure populations. This study examined the Oregon Food Bank's Seed to Supper program which situates garden-based learning in food insecure communities. Through a mixed-methods community-based research process, this study found that community building, learner empowerment and sustainability leadership in place-based learning garden programs increased access to locally grown foods for food insecure populations. When food insecure populations participated in these learning garden programs they often engaged in practices described in the literature as the "web of …
The Role Of Clay Minerals In The Transformation Of E. Coli, Ekaterini Porttellou
The Role Of Clay Minerals In The Transformation Of E. Coli, Ekaterini Porttellou
Dissertations and Theses
No abstract provided.
Slave Drivers; Increased Foraging By Host Workers Under The Slave-Making Ant Plotomognathus Americanus, Kevin Purce
Slave Drivers; Increased Foraging By Host Workers Under The Slave-Making Ant Plotomognathus Americanus, Kevin Purce
Dissertations and Theses
No abstract provided.
The Effects Of Pleistocene Climatic Change On The Phylogeography Of Euploea Mulciber (Lepidoptera; Nymphalidae; Danainae), Elva Yang
Dissertations and Theses
No abstract provided.
Anatomical Analysis Of The Feedback Projections From Extrastriate Cortex To Area 18 In Ferret Visual Cortex, Moody Saint Louis
Anatomical Analysis Of The Feedback Projections From Extrastriate Cortex To Area 18 In Ferret Visual Cortex, Moody Saint Louis
Dissertations and Theses
The purpose of this thesis is to characterize the cortical inputs to area 18 of ferret visual cerebral cortex. Contrary to feedforward connections, feedback connections are presumed to have a modulatory influence on the responses of lower order neurons providing information already processed. Input from feedback connections can supposedly elicit changes in the response to stimuli within the receptive field and may be involved in the role of discriminating objects relative to the background. The aim of our set of experiments was to fully analyze and compare the anatomical characteristics of feedback connections to area 18 from extrastriate areas as …
Feasibility Study Of Trans-Cranial Direct Current Stimulation In Presence Of Brain Tumor, Abhilash Nair
Feasibility Study Of Trans-Cranial Direct Current Stimulation In Presence Of Brain Tumor, Abhilash Nair
Dissertations and Theses
Trans-cranial Direct Current Stimulation has been shown to modulate cortical neuronal activity. Weak constant current is applied to the scalp using electrodes, leading to sub-threshold changes in neuronal membrane potential. Before actual clinical stimulation is performed, such systems are validated by simulating the stimulation and the resulting current flow patterns using finite element solvers. However, the reliability of such models depends upon the accuracy with which the underlying anatomy has been modeled [1]. In earlier studies it has been shown that the current flow patterns within the brain are altered due to the presence of lesioned brain tissues[2]. Here we …
Relative Heart Ventricle Mass And Cardiac Performance In Amphibians, Gregory Joseph Kluthe
Relative Heart Ventricle Mass And Cardiac Performance In Amphibians, Gregory Joseph Kluthe
Dissertations and Theses
This study used an in situ heart preparation to analyze the power and work of spontaneously beating hearts of four anurans (R. marina, L. catesbeianus, X. laevis, P. edulis) and three urodeles (N. maculosus, A. tigrinum, A. tridactylum) in order to elucidate the meaning of relative ventricle mass (RVM) in terms of specific cardiac performance variables. This study also tests two hypotheses: 1) the ventricles of terrestrial species (R. marina, P. edulis, A. tigrinum) of amphibians are capable of greater maximum power outputs (Pmax) compared to aquatic species (X. laevis, A. tridactylum, N. maculosus, L. catesbeianus) and, 2) …
Metabolic Support Of Anaerobiosis In Embryos Of The Annual Killifish Austrofundulus Limnaeus, Andrew Mccracken
Metabolic Support Of Anaerobiosis In Embryos Of The Annual Killifish Austrofundulus Limnaeus, Andrew Mccracken
Dissertations and Theses
Embryos of the annual killifish Austrofundulus limnaeus display a remarkable tolerance to anoxia during development, most notably during embryonic diapause. Little is known about the metabolic or enzymatic changes that accompany this state of anoxia tolerance. This study examined the metabolic changes associated with exposure to anoxia by measuring the activity of the enzyme phosphoenolpyruvate carboxykinase (PEPCK), and by profiling the concentration of 31 metabolites ranging from amino acids to citric cycle intermediates at 4 different developmental stages, diapause 2 (DII), 4 days post diapause (dpd), 12 and 22 dpd. Embryos of A. limnaeus showed stage specific changes in concentrations …
Externally-Expressed Fluorescence Across Sexes, Life Stages, And Species Of Spiders, Erin Brandt
Externally-Expressed Fluorescence Across Sexes, Life Stages, And Species Of Spiders, Erin Brandt
Dissertations and Theses
Although all spiders possess fluorophores in their hemolymph, the expression of external fluorescence is much more restricted. The purpose of this study was to evaluate differences in externally-expressed fluorescence between sexes, life stages, and species of spiders. To approach this question, we developed novel instrumentation to capture fluorescence with photographs of our specimens. We paired these fluorescence measurements with spectrometer measurements to attempt to determine the role that fluorescence plays in the overall coloration in spiders. The study was divided into four sections. First, we examined how fluorescence varies in sexes and life stages in Misumena vatia, an ambush predator …
Causes And Consequences Of Mitochondrial Variation In Caenorhabditid Nematodes, Kiley Ann Hicks
Causes And Consequences Of Mitochondrial Variation In Caenorhabditid Nematodes, Kiley Ann Hicks
Dissertations and Theses
Mitochondria are dynamic organelles that harbor their own stream-lined genome and generate much of the ATP necessary to sustain eukaryotic life via an electron transport chain (ETC). Because of the central role for mitochondria in organismal physiology, mitochondrial genetic and phenotypic variation can alter organismal fitness and affect population genetic and evolutionary outcomes. Despite the far-reaching relevance of mitochondria to evolutionary processes and human health, we lack a basic understanding of the causes and consequences of mitochondrial genetic and phenotypic variation. In this thesis, I quantified mitochondrial reactive oxygen species (ROS), membrane potential (δΨM), and mitochondrial morphological traits within Caenorhabditis …
Use Of Two-Dimensional Agarose-Gel Analysis To Characterize Processing Of Uv-Irradiated Plasmids And The Composition Of The Replisome Following Uv-Induced Arrest, Harout Arthur Jeiranian
Use Of Two-Dimensional Agarose-Gel Analysis To Characterize Processing Of Uv-Irradiated Plasmids And The Composition Of The Replisome Following Uv-Induced Arrest, Harout Arthur Jeiranian
Dissertations and Theses
In this thesis, I address two fundamental questions related to our understanding of how DNA damage is processed and repaired during replication. Using Two-dimensional (2-D) agarose gel analysis, I first examine whether DNA damage on plasmids introduced by transformation is processed in a manner similar to that observed on endogenously replicating plasmids and the chromosome. The original intent for using this approach was to develop a technique that could examine how different DNA adducts would be repaired in various sequence contexts. However, I found that distinct differences exist between the processing of DNA damage on transforming plasmids and the chromosome. …