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Full-Text Articles in Life Sciences

Development Of A Biosensor For Investigating Membrane Curvature Sorting, Joshua C. Black Nov 2013

Development Of A Biosensor For Investigating Membrane Curvature Sorting, Joshua C. Black

Electronic Theses and Dissertations

The physical structure of cellular membranes plays a critical role in lipid and protein sorting. A novel biosensor was developed to probe the influence of curvature on sorting. This biosensor mimics large, two-dimensional membranes in dynamic equilibrium, achieves high spatial resolution between curvature and molecules of interest, and has high sensitivity, enough for single particle detection. The biosensor consists of continuous supported lipid bilayer formed over nanoparticles (40 to 200 nm diameter) deposited on a glass substrate. The nanoparticles determine the extent of curvature. This biosensor is the first to observe large-scale 2-dimensional diffusion of biomolecules on a supported lipid ...


Role Of Camkii In Pancreatic Alpha Cells, Brooke A. Buckland Aug 2013

Role Of Camkii In Pancreatic Alpha Cells, Brooke A. Buckland

Electronic Theses and Dissertations

Calcium/calmodulin-dependent protein kinase II (CaMKII) has been identified as an important modulator in controlling electrical activity in neurons and the heart; however, a role for CaMKII in pancreatic alpha cell signaling has not been previously reported. Upon activation by calcium/calmodulin, CaMKII phosphorylates proteins involved in intracellular calcium homeostasis by inducing downstream effects such as an increase in AMPA-receptor single channel conductance, potentiation of L-type voltage dependent calcium channels, and enhanced surface expression of inhibitory GABAA-receptors. In the pancreas, an increase in intracellular calcium drives secretion of glucagon from alpha cells within the Islets of Langerhans. α-cells ...


Evolution Of Xenopus Tropicalis Mc2r: Expression And Activation, Perry Victoria Davis Aug 2013

Evolution Of Xenopus Tropicalis Mc2r: Expression And Activation, Perry Victoria Davis

Electronic Theses and Dissertations

The structure and functional relationship between the melanocortin-2 receptor (MC2R) and adrenocorticotropic hormone (ACTH) is the most complex of the melanocortin gene family. Prior studies had been done on amniote tetrapod MC2Rs (e.g., mammals); this study analyzed the expression and activation of MC2R by an anamniote tetrapod, Xenopus tropicalis (xtMC2R). An immunofluorescence approach, done on the expression of xtMC2R in Chinese Hamster Ovary cells (CHO cells), indicated that the trafficking of xtMC2R to the plasma membrane required co-expression with a tetrapod MRAP1(melanocortin-1 receptor accessory protein). A cAMP-reporter assay was used to show that xtMC2R can activated by human ...


Vegetation Response After Invasive Tamarix Spp. Removal In The Riparian Zone And Semi-Arid Rangeland Ecosystems, Hisham Nagi El Waer Aug 2013

Vegetation Response After Invasive Tamarix Spp. Removal In The Riparian Zone And Semi-Arid Rangeland Ecosystems, Hisham Nagi El Waer

Electronic Theses and Dissertations

Removal of Tamarix spp. (a.k.a. tamarisk, saltcedar, Athel) invasion is often involved in restoration of Western, riparian habitat; however monitoring of vegetation after removal is often neglected and thus opportunity for adaptive management lost. To address this need, I have conducted three and half years of monitoring vegetation response after invasive Tamarix removal in twenty-five sites on the East and Western Colorado, starting fall 2009. I am also comparing six different methodologies: Point intercept, line transect, nearest neighbor, meter-square quadrats, nested Whittaker plots, and densitometer with the objective of developing monitoring protocols that can be used by scientists ...


Host Use And Geographic Variation In Fall Webworms (Hyphantria Cunea), Katrina J. Loewy Jun 2013

Host Use And Geographic Variation In Fall Webworms (Hyphantria Cunea), Katrina J. Loewy

Electronic Theses and Dissertations

Host use in herbivores is determined by a variety of ecological drivers, including bottom-up and top-down selective pressures such as host abundance, host plant quality, and parasitism pressure. If the relative importance and strength of interactions among these selective conditions change over an herbivore’s geographic range, local patterns of host use should change in response, evident in differing diet breadths. The fall webworm (Hyphantria cunea) is a widespread, polyphagous moth with two color morphs, red and black-headed. In the eastern United States, fall webworms feed on dozens of plant species and previous research demonstrated that host plant abundance was ...


Novel Functions For Neuronal Rna Processing Bodies In The Control Of Axon Terminal Growth In Drosophila Melanogaster, Sarala Joshi Pradhan Jan 2013

Novel Functions For Neuronal Rna Processing Bodies In The Control Of Axon Terminal Growth In Drosophila Melanogaster, Sarala Joshi Pradhan

Electronic Theses and Dissertations

In this thesis we first characterized neuronal functions for HPat/Pat1, a core component of RNA processing bodies or "P bodies". We show that hpat mutants exhibit a strong synaptic hyperplasia at the developing and acutely stimulated Drosophila larval neuromuscular junctions (NMJs). The synaptic defects observed in hpat mutants are associated with rearrangement of the axonal microtubule cytoskeleton suggesting that HPat negatively regulates presynaptic microtubule-based growth during NMJ development. Interestingly, we also found that both pre-and postsynaptic HPat expression controlled rapid axon terminal growth in response to acute spaced synaptic stimulation. We also demonstrate that HPat interacts genetically with the ...


Regulation Of Actin Dynamics During Drosophila Germband Extension, Ashley M. Motlong Jan 2013

Regulation Of Actin Dynamics During Drosophila Germband Extension, Ashley M. Motlong

Electronic Theses and Dissertations

Convergent extension is a process that occurs in the development of a wide variety of organisms, including gastrulation in the Drosophila embryo to begin to lay out the adult body plan. In fly embryos, this is known as germband extension and is mainly driven by cell intercalation or neighbor exchange by planar polarized cell-cell interface contraction to shorten the tissue along the dorsal-ventral axis. In this thesis, I show that interface contraction consists of phases of fast interface shortening and intervals of stable interface size. My data also suggests that regulation of F-actin aggregates at these shrinking interfaces is important ...


X-Band Rapid-Scan Epr, Deborah Gale Mitchell Jan 2013

X-Band Rapid-Scan Epr, Deborah Gale Mitchell

Electronic Theses and Dissertations

The advantages of rapid-scan EPR relative to CW and pulse techniques for samples with long longitudinal relaxation time T1 (Ns0 defects in diamond, N@C60, and amorphous hydrogenated silicon), heterogeneous samples (crystalline 1:1 α,γ-bisdiphenylene-β-phenylallyl (BDPA):benzene), lossy samples (aqueous nitroxyl radicals), and transient radicals (5-tert-butoxycarbonyl-5-methyl-1-pyrroline-N-oxide (BMPO)-superoxide adduct) were studied.

For samples with long relaxation times, CW (continuous wave) EPR is challenging due to power saturation and distortions from passage effects. In rapid-scan EPR, the field is swept through resonance in a time that is short relative to T2. In rapid-scan EPR, the ...


Mitochondrial Glutathione Transport: Implications For Bcl-2 And Neuronal Survival, Heather Marie Wilkins Jan 2013

Mitochondrial Glutathione Transport: Implications For Bcl-2 And Neuronal Survival, Heather Marie Wilkins

Electronic Theses and Dissertations

Oxidative stress is a contributing factor to many neurodegenerative diseases. In particular, mitochondria are a key source of oxidative stress due to electron leakage at the level of the electron transport chain. To combat the endogenous production of reactive oxygen and reactive nitrogen species mitochondria are equipped with several redox-cycling systems, such as glutathione (GSH). Mitochondrial GSH has been shown to be a critical reservoir of this antioxidant, where selective depletion of mitochondrial GSH can induce apoptosis in several systems. Many studies have intricately linked Bcl-2 to cellular GSH status and it has been previously shown that Bcl-2 is a ...


Isolation And Characterization Of A Full Length Retrotransposon: Cr1, Cassandra Michelle Weason Jan 2013

Isolation And Characterization Of A Full Length Retrotransposon: Cr1, Cassandra Michelle Weason

Electronic Theses and Dissertations

Transposable elements (TE) have been found in all genomes and have clearly had a major impact on genomic evolution. The described research takes advantage of an abundant transposable element present in the genomes of Anseriformes, called Chicken Repeat 1 (CR1). Previous studies in Anseriformes suggest that CR1 is presently active in recent evolutionary time (St. John, 2004). A fully functional CR1 element itself is approximately 4.5kb long (Kajikawa, 1997), where almost all inserts are truncated at the 5' end. Because of this, it has been a challenge to isolate a full length, active element. In this study, two CR1 ...


Native Grass And Forb Establishment In Post-Agricultural Soil, Courtney Hall Jan 2013

Native Grass And Forb Establishment In Post-Agricultural Soil, Courtney Hall

Electronic Theses and Dissertations

Restoration of degraded and abandoned agricultural land in arid and semiarid climates is a global problem. The erratic patterns of precipitation these lands experience makes restoration of a plant community difficult. Application of supplemental irrigation and inoculation with arbuscular mycorrhizal fungi (AMF) are two restoration techniques that have been suggested to overcome deficits in natural precipitation. The effects and the interactions of irrigation and seeding date on the ground cover of intended species and unintended exotic species were tested in a post-agricultural restoration experiment in south-central Colorado, USA. The greatest ground cover of intended species and lowest ground cover of ...


Biophysical Approaches To Human Genetic Disease: Adsl Deficiency As A Model, Stephen P. Ray Jan 2013

Biophysical Approaches To Human Genetic Disease: Adsl Deficiency As A Model, Stephen P. Ray

Electronic Theses and Dissertations

Biophysical tools are becoming more useful in approaching human genetic disease. The pathogenic mechanisms behind many disorders have been attributed to protein loss of function or gain in toxic function. For example, changes in the protein Adenylosuccinate Lyase (ADSL) lead to ADSL deficiency, a disorder that causes symptoms ranging from epilepsy to expression of autistic features. Biophysics offers different tools to study intrinsic properties of proteins. We have applied such tools to study the enzyme kinetics and protein stability of ADSL and two mutations (R426H and R303C) to formulate better hypotheses regarding the pathogenic mechanism. Enzyme kinetic findings indicate a ...


A Role For Dynamin-Dependent Endocytosis During Drosophila Gastrulation, Marissa Kay Kuhl Jan 2013

A Role For Dynamin-Dependent Endocytosis During Drosophila Gastrulation, Marissa Kay Kuhl

Electronic Theses and Dissertations

Gastrulation, a process conserved among many higher organisms, is the directed migration of cells into layers that will establish various tissues targeted to become anatomical structures. This process is accomplished through another conserved morphogenetic event, known as cell intercalation. Early in development, this movement of cells within an organized tissue leads to unique cellular arrangements where neighboring cells contract their shared interfaces in order to meet at a shared vertex. In this thesis, I present work that demonstrates a requirement for Dynamin-dependent endocytosis during these contraction events. Using quantitative analysis, I have identified varied cell behaviors during experiments which knockdown ...


Evolution Of Melanocortin-2 Receptor Activations: Studies On A Mammal And A Fish, Liang Liang Jan 2013

Evolution Of Melanocortin-2 Receptor Activations: Studies On A Mammal And A Fish, Liang Liang

Electronic Theses and Dissertations

The structure and function relationship between melanocortin-2 receptor (MC2R) and ACTH are the most complicated in melanocortin receptor gene family. A comparative study on the activation of human and rainbow trout MC2R will provide a useful model system for understanding how ACTH emerged as the sole ligand for the MC2R of bony vertebrates. This dissertation will discuss how studies utilizing analogs of hACTH(1-24) have revealed two critical amino acid motifs in this ligand (HFRW and KKRRP) which are required for the activation of MC2R. In addition, the KKRRP motif functioned as the unique binding site for MC2R that directly ...


Seeded Propagation Of Tau Fibrils, Paul David Dinkel Jan 2013

Seeded Propagation Of Tau Fibrils, Paul David Dinkel

Electronic Theses and Dissertations

In various neurodegenerative diseases, including Alzheimer's disease, progressive supranuclear palsy, Pick's disease, and corticobasal degeneration, the deposition of fibrils composed of misfolded tau protein is observed. Recent evidence suggests that tau fibrils transfer between cells and spread throughout the brain, underscoring the significance of fibril propagation.

Six tau isoforms exist in the adult human brain that can be grouped into 4-repeat (4R) tau and 3-repeat (3R) tau based on the presence or absence of the second of four microtubule binding repeats. We demonstrate in vitro that seeded fibril growth, a prerequisite for the spreading of the tau pathology ...