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An Optogenetic Brain-Machine Interface For Spatiotemporal Neuromodulation, Ryan Andrew Baumgartner Dec 2014

An Optogenetic Brain-Machine Interface For Spatiotemporal Neuromodulation, Ryan Andrew Baumgartner

Theses and Dissertations

Direct neural stimulation has recently become a standard therapy for neurological disorders such as Parkinson's Disease, Essential Tremors, and Dystonia. Currently, deep brain electro-stimulation and neuro-pharmaceutical treatments are the dominant therapeutic options available to the public. As our understanding of brain function and neurological diseases improves, we are able to develop more advanced neuromodulation techniques. These methods could become viable treatment solutions for treating brain dysfunction. Optogenetics, first introduced by a research team led by Karl Deisseroth at Stanford University, has proved to be a versatile technique with remarkable potential to be used in treatments for brain disorders, dysfunction, and …


Phosphorus Recycling By Profunda Quagga Mussels In Lake Michigan, Caroline Mosley Dec 2014

Phosphorus Recycling By Profunda Quagga Mussels In Lake Michigan, Caroline Mosley

Theses and Dissertations

Quagga mussels (Dreissena rostiformis bugensis) act as ecosystem engineers in the southern basin of Lake Michigan, altering physical habitats and biogeochemical processes. Adapted to cold and oligotrophic conditions, profunda quagga mussels thrive on the soft substrate of deeper depths. At a 55 m site (10,000 mussels m-2) offshore from Milwaukee, WI, profunda mussel biomass (g m-2) was 1/3 of biomass (g m-2) measured at a 10 m comparison site (5,000 mussels m-2). Higher densities but less biomass is due to profunda mussels having less tissue for a given length and the population per m2 comprising of mostly small mussels ( …


Impact Of Gestational Exposure To 2,3,7,8-Tetrachlorodibenzo-P-Dioxin On T Lymphocyte Development, Lori S. Ahrenhoerster Dec 2014

Impact Of Gestational Exposure To 2,3,7,8-Tetrachlorodibenzo-P-Dioxin On T Lymphocyte Development, Lori S. Ahrenhoerster

Theses and Dissertations

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a ubiquitous environmental contaminant and the best characterized agonist of the arylhydrocarbon receptor (AHR), a transcription factor crucial to the detoxification of numerous xenobiotics. Studies in animals show that TCDD is immunosuppressive in adult exposures, and epidemiological studies have found an association between TCDD exposure and hematologic cancers. Additionally, developmental exposure to TCDD has been shown to increase the likelihood of autoimmunity and to impair immune response to later-life infections. The cells of the immune system are all descended from multipotent hematopoietic stem cells (HSCs) that originate in the fetus. This multipotency, defined as the ability to …


Alcohol Use Disorders And An Fmri Stress Task: A Connectivity Analysis, Natasha E. Wright Dec 2014

Alcohol Use Disorders And An Fmri Stress Task: A Connectivity Analysis, Natasha E. Wright

Theses and Dissertations

Little research has been conducted on neuronal stress processing in individuals

with alcohol dependence (AD). The present study examined neural stress response in AD individuals compared to controls using an fMRI stress task, assessing amygdala

activation and its connectivity to the medial prefrontal cortex (mPFC). Further, the study

analyzed the impact of hormone levels and subjective stress on frontal-limbic

connectivity patterns.

Ten abstinent AD individuals and 11 controls were recruited. Subjects

participated in an fMRI stress task. A region of interest (amygdala) analysis was

conducted using area-under-the-curve. This activation was then examined in a whole brain functional connectivity analysis. Follow-up …


Foot And Ankle Kinematic And Lower Extremity Muscle Activity During Descent From Varying Step Heights, Emily Gerstle Dec 2014

Foot And Ankle Kinematic And Lower Extremity Muscle Activity During Descent From Varying Step Heights, Emily Gerstle

Theses and Dissertations

Ankle injuries are common during activities of daily living, particularly in negotiation of steps. Previous studies examining steps have generally focused on the ankle, knee, or hip and descent of multiple steps. Joint motion within the foot, utilizing a multi-segment foot model, during step descent has not been extensively studied. Although peroneal muscle activity differences have been identified between participants with healthy and unstable ankles during static activities, little is known about peroneal activity during activities of daily living. A better understanding of the foot kinematics and muscle activity in persons with uninjured ankles may help future studies elucidate the …


The Role Of Brain-Synthesized E2 In Hippocampal Learning And Memory Consolidation In Female Mice, Jennifer Tuscher Dec 2014

The Role Of Brain-Synthesized E2 In Hippocampal Learning And Memory Consolidation In Female Mice, Jennifer Tuscher

Theses and Dissertations

The potent estrogen 17beta-Estradiol (E2) plays a critical role in neuroprotection, serving as an important trophic factor for neurons in the hippocampus, basal forebrain, and prefrontal cortex (Brinton, 2001). In the hippocampus, E2 promotes neurogenesis (Tanapat et al., 1999, Prange-Kiel et al., 2006), protects against cell death after ischemic injury (Garcia-Segura et al., 2001, Zhao and Brinton, 2007), and helps maintain spine morphology crucial for synaptic connectivity and memory (Woolley et al., 1990; Gould et al., 1990, Woolley and McEwen, 1992, Li et al., 2004). However, the mechanisms through which E2 promotes synaptic plasticity and enhances memory function are largely …


Novel Protein Secretion And Chitin Utilization Machinery Of Flavobacterium Johnsoniae, Sampada Suresh Kharade Dec 2014

Novel Protein Secretion And Chitin Utilization Machinery Of Flavobacterium Johnsoniae, Sampada Suresh Kharade

Theses and Dissertations

Flavobacterium johnsoniae, a member of phylum Bacteroidetes, is a gliding bacterium that digests insoluble chitin. A novel protein secretion system, the Type IX secretion system (T9SS), secretes the motility adhesins SprB and RemA and is also required for chitin utilization. In order to understand F. johnsoniae chitin utilization and the role of the T9SS, Fjoh_4555 (chiA) was targeted for analysis. Disruption of chiA resulted in cells that failed to digest chitin and complementation restored this ability. Antisera raised against ChiA were used to characterize its secretion. ChiA was secreted in soluble form by wild-type cells but remained cell-associated in T9SS …


An Optimization Method For Estimating Joint Parameters Of The Hip And Knee, Ben Tesch Dec 2014

An Optimization Method For Estimating Joint Parameters Of The Hip And Knee, Ben Tesch

Theses and Dissertations

Biomechanics, generally speaking, concerns the application of engineeringprinciples to the study of living things. This work is concerned withhuman movement analysis, a subfield of biomechanics, where the methodsof classical mechanics are applied to human movement. This field hascontributed to the general understanding of human movement, and itstechniques are used in the diagnosis and treatment of disease. Centralto the field is the process of measuring human movement. Since classicalmechanics deals with the motion of rigid bodies, and ideal measurementsystem would be able to accurately record the exact pose --- combinedposition and orientation --- of the bones. The techniques that reachthis ideal …


Three Research Essays On Propensity To Disclose Medical Information Through Formal And Social Information Technologies, Wachiraporn Arunothong Dec 2014

Three Research Essays On Propensity To Disclose Medical Information Through Formal And Social Information Technologies, Wachiraporn Arunothong

Theses and Dissertations

Abstract

This dissertation, which is comprised of three essays, examined disclosure propensity of healthcare providers from the US and Thailand and disclosure of personal health problems of healthcare consumers in social media context.

Essay 1: A Deterrence Approach in Medical Data Misuse among Healthcare Providers

Information and communication technology (ICT) have long been available for use in health care. With the potential to improve the quality, safety, and efficiency of health care, the diffusion of these technologies has steadily increased in the health care industry. With the adoption of electronic health records, personal electronics devices, internet connections and social network …


Oligomerization Of The Sterile-2 G-Protein Coupled Receptor In Yeast Cells In The Presence And Absence Of Alpha-Factor Pheromone Using Fluorescence Spectroscopy And Forster Resonance Energy Transfer Analysis, Joel David Paprocki Dec 2014

Oligomerization Of The Sterile-2 G-Protein Coupled Receptor In Yeast Cells In The Presence And Absence Of Alpha-Factor Pheromone Using Fluorescence Spectroscopy And Forster Resonance Energy Transfer Analysis, Joel David Paprocki

Theses and Dissertations

G-protein-coupled receptors (GPCRs) are the largest family of receptors that respond to a wide variety of extracellular stimuli, including molecular ligands such as odorants, neurotransmitters, and hormones, as well as physical agents sigh as light and pressure. The stimulation event results in initiating conformational changes in the structure of the receptor, which further results in the release of the heterotrimeric G-protein; the latter has a variety of functions within signaling pathways in cellular biology. The GPCR explored in this investigation is the Sterile 2 α-factor receptor (Ste2), whose natural function is that of a yeast mating pheromone receptor. Its natural …


The Hippocampus And Adult Neurogenesis: A Neural Circuit With A Common Role In Behavioral Flexibility And Detailed Memory, Brian Pochinski Dec 2014

The Hippocampus And Adult Neurogenesis: A Neural Circuit With A Common Role In Behavioral Flexibility And Detailed Memory, Brian Pochinski

Theses and Dissertations

Work with patient H.M. sparked great interest in the role of the hippocampus in learning and memory. Later, the findings that new neurons are born in the adult dentate gyrus (DG) and that they become functionally integrated in neural circuits created new excitement in the field of learning and memory. While there is ample evidence that the hippocampus and adult neurogenesis are involved in learning and memory, similar inconsistencies in both areas have clouded interpretations of their precise role. We propose that studying the role of hippocampus and neurogenesis in the DG must be merged into a more cohesive field …


Interaction Of Rhizobium Sp. Strain Irbg74 With A Legume (Sesbania Cannabina) And A Cereal (Oryza Sativa), Shubhajit Mitra Dec 2014

Interaction Of Rhizobium Sp. Strain Irbg74 With A Legume (Sesbania Cannabina) And A Cereal (Oryza Sativa), Shubhajit Mitra

Theses and Dissertations

Rhizobium sp. IRBG74 (IRBG74) develops a classical nitrogen-fixing symbiosis with the legume Sesbania cannabina and also promotes the growth of rice (Oryza sativa), but not much is known about the rhizobial determinants important for these interactions. We hypothesize that Rhizobium sp. IRBG74 utilizes similar mechanisms to endophytically colonize both legume and cereal hosts. In this study, we analyzed the colonization of rice and S. cannabina using a strain of IRBG74 marked with β-glucuronidase (GUS) and Green Fluorescent Protein (GFP). IRBG74 infected both of the host plants through crack entry under submerged conditions, but showed root hair mediated infection under aerobic …


Gene Regulatory Pathways Driving Central Nervous System Regeneration In Zebrafish, Ishwariya Venkatesh Dec 2014

Gene Regulatory Pathways Driving Central Nervous System Regeneration In Zebrafish, Ishwariya Venkatesh

Theses and Dissertations

Damage to the central nervous system (CNS) circuitry of adult mammals results in permanent disability. In contrast, the ability to regenerate damaged CNS nerves and achieve functional recovery occurs naturally in fish. The ability of fish to successfully regrow damaged CNS nerves is in part a consequence of their ability to re-express key neuronal growth-associated genes/proteins in response to CNS injury. On such protein is Growth-Associated Protein-43 (Gap43), a protein which is highly enriched in axonal growth cones during CNS development and regeneration. Experiments conducted in mammals have demonstrated that ectopic expression of GAP-43 improves axonal re-growth after injury. Using …


Cellular Zinc Trafficking: The Zinc Proteome And Its Reactions With Cadmium, Mohammad Ali Namdarghanbari Dec 2014

Cellular Zinc Trafficking: The Zinc Proteome And Its Reactions With Cadmium, Mohammad Ali Namdarghanbari

Theses and Dissertations

Metals play a crucial role in living systems. Iron, zinc, copper, molybdenum, and manganese are involved in many essential biological activities. Among transition metals, zinc after iron is the most abundant transition metal in the human body and the most abundant in the brain. It exists in more than 3000 proteins, which comprise about 10% of the human proteome. Zn2+ dyshomeostasis is associated with chronic diseases such as metabolic syndrome, diabetes and related complications, bone loss, growth retardation in young children, and neurological and behavioral problems. Despite a good knowledge obtained for metabolism of some metal ions such as copper, …


Landscape Genetics Of The American Badger: Understanding Challenges In Elusive Species, Elizabeth Marie Kierepka Dec 2014

Landscape Genetics Of The American Badger: Understanding Challenges In Elusive Species, Elizabeth Marie Kierepka

Theses and Dissertations

American badgers are one of the most poorly understood carnivores in North America due to their highly elusive, semifossorial lifestyle. To complicate understanding their biology further, badgers possess life history characteristics that predict radically different responses to habitat heterogeneity. In particular, they are considered grassland specialists, so their movement and population viability could be highly dependent on grassland habitats. Badgers are also highly mobile, which suggests they experience high gene flow. Predicting how these life history traits impact gene flow, however, is difficult based on the high diversity in responses to landscape heterogeneity among carnivores. To assess how landscape heterogeneity …


Part I: Synthesis And Biological Evaluations Of Potent Class L Selective Histone Deacetylase Inhibitors Part Ii: Aqueous Complexes For Efficient Sizebased Separation Of Americium From Curium Part Iii: Designing Strong Chiral Bronsted Acids And Their Application For Oxaxinanones Derivatization And The Aza-Henry Reaction, Joseph Steve Ulicki Dec 2014

Part I: Synthesis And Biological Evaluations Of Potent Class L Selective Histone Deacetylase Inhibitors Part Ii: Aqueous Complexes For Efficient Sizebased Separation Of Americium From Curium Part Iii: Designing Strong Chiral Bronsted Acids And Their Application For Oxaxinanones Derivatization And The Aza-Henry Reaction, Joseph Steve Ulicki

Theses and Dissertations

PART I: SYNTHESIS AND BIOLOGICAL EVALUATIONS OF POTENT CLASS l SELECTIVE HISTONE DEACETYLASE INHIBITORS

Histone deacetylase inhibitors (HDACi) have found a wide variety of medicinal uses and are most noted for their specific apoptotic action towards cancer cells1. Several hydroxamates and tetrapeptides HDACi have since been moved on to phase 1 and 2 clinical trials, with FK228 & SAHA having already been approved for treatment of advanced cutaneous T-cell lymphoma (CTCL). FK228 & SAHA are pan-HDACi which d compounds describes the unselective inhibition for any of the 11 Zn2+-dependent HDAC isoforms. Research in the past five years, has shifted towards …


Role Of Sensation In Altered Phalanx Grip Force In Persons With Stroke, Leah R. Enders Dec 2014

Role Of Sensation In Altered Phalanx Grip Force In Persons With Stroke, Leah R. Enders

Theses and Dissertations

Many individuals experience hand impairment after stroke leading to decreased ability to perform daily living activities. Previous research studies have investigated how stroke survivors' pinch grip control differs from healthy individuals, even though many individuals can only grasp with power grip after stroke. Furthermore, many stroke survivors experience tactile sensory deficit in their paretic limb in addition to motor deficit. It is currently unknown how stroke induced tactile sensory deficit affects power grip force directional control, which is important in terms of preventing object slippage and power grip normal force generation. Additionally it is unknown if power grip could be …


Use Of Photobiomodulation In Osteoclast Formation: Possible Intervention For The Treatment Of Osteoporosis, Lisa Lauren Anderson-Antle Aug 2014

Use Of Photobiomodulation In Osteoclast Formation: Possible Intervention For The Treatment Of Osteoporosis, Lisa Lauren Anderson-Antle

Theses and Dissertations

After critically examining the literature to gain a robust understanding for the pathogenesis of bone loss, specifically osteoporosis, the development of a possible new intervention to prevent or treat osteoporosis was explored. The purpose of this dissertation was to pilot test a new protocol designed to answer the broad research question: Does Near-Infrared Light Emitting Diode (NIR-LED) treatment affect Receptor Activator of Nuclear Factor Kappa-B Ligand (RANKL) induced osteoclastogenesis in a cell culture model?

Osteoporosis is defined as a disease characterized by low bone mass and structural deterioration of bone tissue, leading to bone fragility and an increased susceptibility to …


Th17 Cell-Associated Response To Borrelia Burgdorferi Outer Surface Protein A, Megan Elizabeth Johnson Aug 2014

Th17 Cell-Associated Response To Borrelia Burgdorferi Outer Surface Protein A, Megan Elizabeth Johnson

Theses and Dissertations

Arthritis is a common symptom of Lyme disease, a debilitating condition resulting from infection with Borrelia burgdorferi. A protein found on the surface of B. burgdorferi, outer surface protein A (OspA), is known to elicit an inflammatory immune response involving T helper cells. T helper 17 (Th17) cells are associated with the inflammatory cytokines interleukin-17 (IL-17) and interleukin-23 (IL-23) and have been implicated in the development of Lyme arthritis. The objective of this thesis is to provide further characterization of the immune response to B. burgdorferi OspA. The central hypothesis of this thesis is: Vaccination with OspA will predispose mice …


Biomechanical Evaluation Of A Jackhammering Task With And Without List Assist, Blake Allen Johnson Aug 2014

Biomechanical Evaluation Of A Jackhammering Task With And Without List Assist, Blake Allen Johnson

Theses and Dissertations

The construction and utility industries have relatively high levels of hazardous tasks that impose high physical demands on a worker. For the past decade these industry sectors had one of highest incident rates for non-fatal injuries (BLS, 2013). The task of operating a jackhammer presents several risk factors that promote the high rates of injuries to this industry sector. Until the introduction of the lift assist, relatively few interventions were available to make the task of operating a jackhammer safer. However, no research has been conducted to support that this device is able to make jackhammering safer. The aim of …


Effects Of Active Video Games In The Rehabilitation Of Ankle Sprains And Chronic Ankle Instability, Nathan Maresh Aug 2014

Effects Of Active Video Games In The Rehabilitation Of Ankle Sprains And Chronic Ankle Instability, Nathan Maresh

Theses and Dissertations

INTRODUCTION: Research into the treatment of acute lateral ankle sprains with individuals currently suffering from an acute injury, rather than a history of injury, is sparse. These acute injuries have psychological effects (e.g. confidence in one's readiness to return to play, changes to one's mood, adherence to the rehabilitation) to the individual that must be recognized as they have the potential to affect the rehabilitation process as much as the physical effects. In spite of previous research into the treatment of acute lateral ankle sprains the rate of recurrent injury remains high. With these recurrent ankle sprains comes the development …


Habitat Preferences Of The Common Nighthawk (Chordeiles Minor) In Cities And Villages In Southeastern Wisconsin, Jana M. Viel Aug 2014

Habitat Preferences Of The Common Nighthawk (Chordeiles Minor) In Cities And Villages In Southeastern Wisconsin, Jana M. Viel

Theses and Dissertations

Limited survey data and numerous anecdotal accounts indicate that the Common Nighthawk (Chordeiles minor) is experiencing population declines in Wisconsin. However, the magnitude of the decline is unclear because current avian monitoring efforts are not conducted at dusk when Common Nighthawks are most active nor do they specifically target urban areas such as cities and villages where Common Nighthawks are known to nest on flat graveled rooftops. New urban, crepuscular monitoring methods are needed in order to gain a better understanding of current Common Nighthawk demographics in Wisconsin.

The goal of this thesis was to conduct a baseline study using …


Early Triassic Echinoids Of The Western United States: Their Implications For Paleoecology And The Habitable Zone Hypothesis Following The Permo-Triassic Mass Extinction, Jenna Rolle Aug 2014

Early Triassic Echinoids Of The Western United States: Their Implications For Paleoecology And The Habitable Zone Hypothesis Following The Permo-Triassic Mass Extinction, Jenna Rolle

Theses and Dissertations

Confronted with global climate change and ocean acidification, our collective knowledge of ecosystem response during times of environmental crisis in Earth's ancient past may provide insights towards combating ecological degradation in modern oceans. Early Triassic marine environments were characterized by oceanic warming due in part to elevated levels of atmospheric CO2 and periodic intervals of localized anoxia, resulting in an overall restructuring of faunal dominance, distribution, and biodiversity. Re-assembly of ecological communities during the Early Triassic are largely unknown; however, a previous paleoecological study by Tyler Beatty et al. (2008), suggests that post-extinction recovery length was minimized in shallow …


Development Of Peripheral Innervation In The Frog Xenopus Laevis, Mitali A. Gandhi Aug 2014

Development Of Peripheral Innervation In The Frog Xenopus Laevis, Mitali A. Gandhi

Theses and Dissertations

The skin in Xenopus laevis is innervated by two different sets of mechanosensory neurons at different times during development. Rohon Beard (RB) neurons start differentiating during gastrulation, innervate the embryonic skin and mediate sensory function during hatching. Dorsal Root Ganglion (DRG) neurons start differentiating after neural crest migration, innervate adult epidermal targets and mediate mechanosensory function during larval and adult stages and eventually replace RB neurons. The change in sensory neurons occurs during the transformation of skin, sensory structures, and behavior from their embryonic to their larval forms. We hypothesized that developmental changes in either the sensory end organs or …


Neurophysiological And Morphological Plasticity In Rat Hippocampus And Medial Prefrontal Cortex Following Trace Fear Conditioning, Chenghui Song Aug 2014

Neurophysiological And Morphological Plasticity In Rat Hippocampus And Medial Prefrontal Cortex Following Trace Fear Conditioning, Chenghui Song

Theses and Dissertations

Pavlovian fear conditioning provides a useful model system for investigating the mechanisms underlying associative learning. In recent years, there has been an increasing interest in "trace" fear conditioning, which requires conscious awareness of the contingency of CS and US therefore considered as a rodent model of explicit fear. Acquisition of trace fear conditioning requires an intact hippocampus and medial prefrontal cortex (mPFC), but the underlying mechanisms are still unclear. The current set of studies investigated how trace fear conditioning affects neuronal plasticity in both hippocampus and mPFC in adult rats. Trace fear conditioning significantly enhanced both intrinsic excitability and synaptic …


Memory Retrieval Is Maintained By Intrinsic And Synaptic Plasticity In Prelimbic Cortex, James Otis Aug 2014

Memory Retrieval Is Maintained By Intrinsic And Synaptic Plasticity In Prelimbic Cortex, James Otis

Theses and Dissertations

Abnormally strong memories underlie common disorders including addiction and post-traumatic stress disorder (PTSD). Memory disruption would therefore be beneficial for treatment of these disorders. Evidence reveals that cocaine conditioned place preference (CPP) memories are susceptible to long-lasting disruption during memory retrieval. For example, inhibition of β-adrenergic receptor (β-AR) activity within the prelimbic medial prefrontal cortex (PL-mPFC) prevents cocaine CPP memory retrieval, and this retrieval impairment is both long-lasting and prevents subsequent reinstatement of the CPP. Despite this, whether PL-mPFC β-AR activity is a fundamental mechanism required to maintain retrieval of other memories is unclear. Furthermore, how PL-mPFC β-AR activity maintains …


Zebrafish As A Model For Determining The Mechanisms Causing Deafness In Myh9-Related Disease, Luke David Spychalla Aug 2014

Zebrafish As A Model For Determining The Mechanisms Causing Deafness In Myh9-Related Disease, Luke David Spychalla

Theses and Dissertations

Approximately 1 in 500 infants are diagnosed with hearing loss, and about half of these cases can be traced to genetic defects. Several hundred genes have been implicated in deafness, including MYH9, which codes for the conventional motor protein non-muscle myosin IIA (NMIIA). Mutations in MYH9 lead to syndromic MYH9-related diseases, which include deafness as a variable symptom, as well as non-syndromic autosomal deafness DFNA17. Despite its identification as a deafness gene, the functions of MYH9 in ear development and hearing remain unknown. To study this role, we will use zebrafish as a model. Zebrafish offer significant advantages including established …


Evaluation Of Alternative Culling Strategies For Maintenance Of Genetic Variaton In Bison (Bison Bison), Rachael Marie Toldness Aug 2014

Evaluation Of Alternative Culling Strategies For Maintenance Of Genetic Variaton In Bison (Bison Bison), Rachael Marie Toldness

Theses and Dissertations

Bison (Bison bison) once numbered in the millions and roamed across much of the lower 48 states. By the late 1800s, overhunting had reduced the population to around 1,000 individuals. Strong efforts to establish managed herds have resulted in a steady bison population increase. Currently, six herds are maintained by the U.S. Fish and Wildlife Service (FWS) at National Wildlife Refuges (NWRs) and are intensively managed through annual culling to keep herd size at targeted levels. Although various criteria have historically been used to select individuals for culling, the FWS currently employs an allele frequency based strategy that we have …


Mechanism Of The Hydroxylation Reactions Catalyzed By 4-Hydroxyphenylpyruvate Dioxygenase And Hydroxymandelate Synthase, Dhara D. Shah Aug 2014

Mechanism Of The Hydroxylation Reactions Catalyzed By 4-Hydroxyphenylpyruvate Dioxygenase And Hydroxymandelate Synthase, Dhara D. Shah

Theses and Dissertations

4-Hydroxyphenylpyruvate dioxygenase (HPPD) and Hydroxymandelate synthase (HMS) carry out highly similar complex dioxygenation reactions using the substrates, 4-hydroxyphenylpyruvate (HPP) and dioxygen. HPPD catalyzes decarboxylation, aromatic hydroxylation and substituent migration (NIH shift) in a single catalytic cycle to form homogentisate (HG), whereas HMS catalyzes decarboxylation and aliphatic hydroxylation to give hydroxymandelate (HMA). Wild-type HPPD, HPPD variants and HMS variants produce both native and non-native products. Based on this observation, we have employed a product analysis method with HPP deuterium substitutions (ring or benzylic) that reveal kinetic isotope effects from intermediate partitioning ratios. In this study we offer evidence for the 1) …


Plankton Trophic Structure Within Lake Michigan As Revealed By Stable Carbon And Nitrogen Isotopes, Zachery G. Driscoll May 2014

Plankton Trophic Structure Within Lake Michigan As Revealed By Stable Carbon And Nitrogen Isotopes, Zachery G. Driscoll

Theses and Dissertations

Zooplankton represent a critical component of aquatic food webs in that they transfer energy from primary producers to higher trophic positions. However, their small size makes the application of traditional trophic ecology techniques difficult. Fortunately, novel techniques have been developed that can be used to elucidate feeding information between zooplankton species. I used the analysis of stable carbon and nitrogen isotope ratios to estimate the trophic structure of Lake Michigan's zooplankton community. The major zooplankton species, three size classes of seston, and seston from specific water column depths were collected in 2011 and 2012 for stable isotope analysis. Trophic position …