Life Sciences Commons^™

The Processing Of Amyloid Precursor Protein In The Central Nervous System Of Humans And Rhesus Macaques, Justyna Anna Dobrowolska

All Theses and Dissertations (ETDs)

Alzheimer's disease: AD) is the most common dementia, currently afflicting 30 million people worldwide, with prevalence steadily increasing. Over 99% of AD cases are classified as sporadic, in which the major risk factors are age: greater than 65 years) and the ApoE-ε4 allele: in a gene dose dependent manner). The minority of AD cases: less than 1%) are caused by autosomal dominant inheritance of a genetic mutation in one of three genes: Amyloid Precursor Protein: APP), Presenilin-1: PSEN1), or Presenilin-2: PSEN2). Mutation carriers will generally notice cognitive decline starting at a relatively young age, anytime between their 30s-50s, and eventually …

The Function Of Carmil1 In Migrating Cells, Marc Edwards

All Theses and Dissertations (ETDs)

This dissertation describes the physiological role of the Capping Protein- CARMIL interaction in migrating cells. I establish the CARMIL-CP complex as a key regulator of lamellipodial actin assembly and of lamellipodial dynamics. Membrane ruffling at the leading edge of motile cells and macropinocytosis were also found to be dependent on the CARMIL1-CP interaction. This is consistent with macropinocytosis and ruffling being dependent on a functional and dynamic lamellipodium.: Kerr and Teasdale, 2009).

In chapter two I demonstrate that the CBR of CARMIL1 is competent to inhibit CP in cells. I show that overexpression of the CBR in cells leads to …

Understanding Crx-Associated Retinopathies Using Animal Models, Nicholas Minh Abell Tran

All Theses and Dissertations (ETDs)

Cone-rod homeobox: CRX) protein is a "paired-like" homeodomain transcription factor that is essential for regulating rod and cone photoreceptor transcription. Mutations in human CRX are associated with the dominant retinopathies Retinitis Pigmentosa: RP), Cone-Rod Dystrophy: CoRD) and Leber Congenital Amaurosis: LCA), with variable severity. The goal of my dissertation project was to develop and characterize animal models to understand genetic mechanisms of phenotypic diversity in CRX-associated disease. Heterozygous Crx Knock-Out: KO) mice: "+/-") have normal vision as adults and fail to model the dominant human disease.

We generated two Crx Knock-IN: K-IN) mouse models: CrxE168d2: "E168d2") and CrxR90W: "R90W"), which …

The Diversity Of Quantitative Trait Loci In Yeast Sporulation Efficiency, Kimberly Lorenz

All Theses and Dissertations (ETDs)

A complex trait is one that exhibits continuous phenotypic variation due to genetic variation in many quantitative trait genes: QTGs). The ultimate goal of genetics is to relate genotype to phenotype; in the case of complex traits this requires a better understanding of what types of genes harbor causal natural variation, and what form the variation takes. Here I describe two experiments using the model complex trait of sporulation efficiency in the yeast Saccharomyces cerevisiae, one to specifically investigate how small effects contribute to a quantitative trait and the other to determine whether certain types of genes are more likely …

On The Origin Of Phenotypic Variation: Novel Technologies To Dissect Molecular Determinants Of Phenotype, Francesco Vallania

All Theses and Dissertations (ETDs)

This thesis describes the conception, design, and development of novel computational tools, theoretical models, and experimental techniques applied to the dissection of molecular factors underlying phenotypic variation. The first part of my work is focused on finding rare genetic variants in pooled DNA samples, leading to the development of a novel set of algorithms, SNPseeker and SPLINTER, applied to next-generation sequencing data. The second part of my work describes the creation of a reporter system for DNA methylation for the purpose of dissecting the genetic contribution of tissue-specific patterns of DNA methylation across the genome. Finally the last part of …

Cooperative Tumor Suppression By Arf And P53, Jason Thomas Forys

All Theses and Dissertations (ETDs)

Cancer is a complex genetic disease characterized by the inactivation of tumor suppressor genes and enhanced activity of oncogenes leading to deregulated cellular proliferation. Two tumor suppressor genes, p53 and Arf, play important roles in protecting cells against numerous biological stresses. In response to oncogenic signals, increased ARF expression leads to the activation of p53, which in turn leads to the cessation of cell division or induction of an apoptotic response. Interestingly, p53 coordinates repression of Arf transcription, setting up a negative feedback loop with currently unknown physiological significance. Cells that lack p53 express elevated levels of ARF, but it …

The System I And System Iii Holocytochrome C Synthases In Cytochrome C Biogenesis, Brian San Francisco

All Theses and Dissertations (ETDs)

Cytochromes c are proteins that are involved in important redox reactions in organisms from every kingdom of life. C-type cytochromes, uniquely, possess a covalently bound heme. Since cytochromes c are assembled at their site(s) of function: outside of the cytoplasmic membrane in bacteria, in the chloroplast lumen, or in the mitochrondrial intermembrane space), their assembly poses unique challenges to heme trafficking and post translational modification. Three major systems exist in nature for cytochrome c assembly, termed systems I, II, and III. Using recombinant Escherichia coli, aspects of systems I and III were analyzed, with an emphasis on the synthase protein(s) …

Mutations Of Pdd1 Chromo- And Chromoshadow Domains Reveal Critical Functions For Each During Development Of Tetrahymena Thermophila, Rachel Schwope

All Theses and Dissertations (ETDs)

Pdd1 is a developmentally expressed HP1-like protein of Tetrahymena thermophila that is required during conjugation, when a copy of the cell's transcriptionally silent germline micronucleus differentiates into an active somatic macronucleus. Differentiation of these somatic chromosomes involves genome-wide fragmentation and amplification. These DNA rearrangements are facilitated by an RNAi mechanism, in which small RNAs target silencing histone modifications, H3K9 and H3K27 methylation, to Internal Eliminated Sequences: IESs), which are bound by Pdd1 and later excised from the genome. Pdd1 features two chromodomains, one of which shares homology with that of HP1, and a C-terminal chromoshadow domain. In this study, we …

The Mechanism Of The Gastric Epithelial Stem Cell Response To Metaplastic Injury, Shradha Sachin Khurana

All Theses and Dissertations (ETDs)

Almost nothing is known about the identity of the epithelial stem cell of the gastric corpus, either during normal turnover or in response to injury. Our lab has shown that injection of the selective estrogen receptor modulator tamoxifen leads to near complete atrophy of parietal cells by 3 days and induces expansion of an undifferentiated cell population within the normal stem cell niche in the isthmus of the gastric unit. Here we show that CD44 labels the membranes of such undifferentiated isthmal cells, both in the normal gastric epithelium and when those cells expand fourfold upon injury with tamoxifen. Loss …

The Effects Of Invasive Plants On Biodiversity Across Spatial Scales, Kristin Irene Powell

All Theses and Dissertations (ETDs)

Although introduced plant species are often considered to be one of the most notable anthropogenic threats to biodiversity, their influence on biodiversity remains controversial. Some studies have shown large declines in biodiversity in plant-invaded areas, whereas others have noted that plant invasions are rarely implicated as the cause of species extinctions. This dissertation aims to synthesize this seemingly conflicting literature on the effects of invasive plants on biodiversity. The overarching hypothesis in this research is that the effect of invasive plant species on biodiversity is scale-dependent, and the discrepancy among studies can be explained by a difference in the scales …

Structural Mechanism Of Orthopoxvirus Sabotage Of Mhci Antigen Presentation, William Howard Mccoy Iv

All Theses and Dissertations (ETDs)

Immunomodulatory proteins that subvert major histocompatibility complex class I: MHCI) antigen presentation can help viruses to evade cytotoxic T-lymphocyte: CTL) detection and clearance. Cowpox virus, like other orthopoxvirus family members, is a large DNA virus, whose genomic termini encode numerous immunomodulatory genes, including two ER-resident MHCI saboteurs: CPXV012 and CPXV203). CPXV012 inhibits peptide loading of MHCI within the peptide-loading complex: PLC), while CPXV203 inhibits surface expression of both murine and human MHCI through the use of a C-terminal ER-retention sequence: KTEL). An association: direct or indirect) between CPXV203 and MHCI was first demonstrated in pull-down experiments. This doctoral work explores …

Identification Of Genetic Determinants Of Metastasis And Clonal Relationships Between Primary And Metastatic Tumors, Gaurav Singhal

All Theses and Dissertations (ETDs)

No abstract provided.

Control Of Neuroendocrine Cell Physiology By A Single Transcription Factor, Drosophila Basic Helix Loop Helix Regulator Dimmed, Tarik Hadzic

All Theses and Dissertations (ETDs)

Neuroendocrine cells feature a large capacity for the processing, accumulation and regulated release of bioactive peptides and peptide hormones. The ultrastructural correlate of this regulated secretory pathway is a specialized organelle, called a dense core vesicle: DCV). DCVs are typically larger than conventional, small synaptic vesicles. Past work has identified intrinsic DCV proteins: non-cargo proteins, like the processing enzyme, carboxypeptidase) or ancillary ones that play a role in DCV trafficking and exocytosis: like CAPS, the Ca2+-dependent activator protein for secretion). Currently, there is a lack of understanding of the developmental and physiological mechanisms that permit neurosecretory cells to coordinate and …

Characterization Of The Placenta-Specific 8.1 Gene Function During Zebrafish Embryogenesis, Haiting Ma

All Theses and Dissertations (ETDs)

The PLAC8 gene encodes for a small, cysteine-rich protein conserved in vertebrates that is a member of a large family of PLAC8-motif containing proteins with diverse functions in animals, plants, and algae. Recently, high levels of PLAC8 expression have been detected in aggressive colorectal cancer and invasive breast cancer, and potentially contributing to the cancer pathogenesis. However, the molecular and cellular functions of PLAC8 in vertebrate development, homeostasis, and disease remain unclear. To determine the function of PLAC8 under disease and normal conditions, in this thesis work, I identified plac8.1 as a PLAC8 homolog in zebrafish, a vertebrate model system …

Metagenomic Analyses Of The Human Gut Virome, Alejandro Reyes

All Theses and Dissertations (ETDs)

The human gut harbors tens of trillions of microbes belonging to all three domains of life, Bacteria, Archaea, and Eukarya; most are members of Bacteria. These organisms collaborate and compete for functional niches and physical space: habitats), together forming a continuously functioning metabolic organ that influences many aspects of host biology. The factors that drive the assembly, determine the stability, and shape the adaptive responses of the gut microbiota to a variety of perturbations are the subject of intense study as greater appreciation is gained of the importance of this microbial community for human health. My thesis focused on the …

Characterization Of Human Gut Microbiota Dynamics Using Model Communities In Gnotobiotic Mice, Nathaniel Patrick Mcnulty

All Theses and Dissertations (ETDs)

The human gut is colonized by a diverse array of microbes, collectively referred to as the microbiota. The microbiota's complexity poses significant challenges in characterizing the rules dictating its assembly, inferring the functional roles of its component species, and understanding how communities sense and respond to changes in their habitat. We developed defined, representative model communities comprised of sequenced human gut bacteria that could be characterized in a highly controlled manner in gnotobiotic mice, plus a suite of scalable molecular tools for assaying community properties. These tools were first used to evaluate how the microbiota is impacted by probiotic bacterial …

The Physiological And Morphological Responses Of The Bladder Urothelium To Differential Injury, Kristina Marie Stemler

All Theses and Dissertations (ETDs)

The bladder is the site of various diseases such as urinary tract infections: UTI), bladder pain syndrome/interstitial cystitis: BPS/IC), and bladder cancer. UTIs and BPS/IC primarily afflict women and treatment costs over $5 billion and almost $200 million respectively in 2006. Quality of life in BPS/IC patients is low; comparable to individuals with end stage renal disease. Recent research has identified a role for the epithelial lining of the bladder, which is usually targeted by these afflictions, in potentially contributing to enhancing pain. The bladder epithelium also showcases a rapid ability to regenerate after injury.

Knowledge of the contribution of …

Intermediate Level Mechanisms Supporting Face Perception, Eric J. Feczko

All Theses and Dissertations (ETDs)

I propose that the intermediate neural mechanisms involved in face processing may be better understood by studying concentric form-from-structure integration. This dissertation involves behavioral adaptation and masking experiments that provide evidence regarding whether face perception and concentric form-from-structure perception engage a common processing mechanism.

Despite faces being complex visual stimuli, humans are able to perceive and identify faces rapidly. Studies of face perception strongly suggest that this ability involves processing the arrangement of the face features. Although high-level aspects of face perception have been studied extensively, less is known about the intermediate mechanisms involved in face processing. Converging evidence has …

The Influence Of Diet On The Mammalian Gut Microbiome, Brian David Muegge

All Theses and Dissertations (ETDs)

The mammalian gut is residence to a large microbial community whose collective set of millions of genes: microbiome) encodes a vast array of functions, including many that process dietary components. Few tools are available to change the microbiome's properties to promote host health because the factors governing community assembly and operation are poorly understood. My thesis focused on the impact of one factor, host diet.

I used a variety of experimental and computational methods to perform a comparative metagenomic study of the fecal communities of 39 diverse mammals to assess microbiome variation. These animals included herbivores, omnivores and carnivores representing …

Concentration Coding In The Accessory Olfactory System, Hannah Ada Arnson

All Theses and Dissertations (ETDs)

Understanding how sensory systems encode stimuli is a fundamental question of neuroscience. The role of every sensory system is to encode information about the identity and quantity of stimuli in the environment. Primary sensory neurons in the periphery are faced with the task of representing all relevant information for further processing by downstream circuits, ultimately leading to detection, classification and potential response. However, environmental variability potentially alters stimulus properties in non-relevant ways. Here, we address these problems using the mouse accessory olfactory system: AOS) as a model. The AOS is an independent olfactory system possessed by most terrestrial vertebrates, although …

Hematopoietic Stem Cells And Progenitors In Murine Autoimmune Arthritis, Kwadwo Asare Oduro Jr.

All Theses and Dissertations (ETDs)

Although the physiological role of stem cells in generating and maintaining a functional biological system is widely appreciated, very little is known about the behavior of these cells in pathological conditions. If and how these primitive cells are affected by a disease process or may contribute to the disease process has not been adequately explored. We have studied the Hematopoietic System, with particular emphasis on Hematopoietic Stem Cells: HSCs) and Progenitors, in a spontaneous murine autoimmune arthritis model. We found that these mice have a systemic increase in myeloid cells, which correlated with an increased frequency of granulocyte-monocyte progenitors relative …

A Role For Interferon Stimulated Gene-15 (Isg15) During Chikungunya Virus Infection, Scott Werneke

All Theses and Dissertations (ETDs)

Abstract of the Dissertation

A Role for Interferon Stimulated Gene-15: ISG15) During Chikungunya Virus Infection

By

Scott William Werneke

Doctor of Philosophy in Biology and Biomedical Science

(Immunology)

Washington University in St. Louis, 2013

Professor Deborah J. Lenschow, Chairperson

Chikungunya fever is caused by Chikungunya virus: CHIKV), an infectious disease that is characterized by severe joint and muscle pain in humans. The latest outbreak of CHIKV, which began in 2005, has affected millions of people across India, Singapore, and the Indian Ocean Island region. Type I interferon: IFN), which mediates protection against many different viruses through the upregulation of interferon …

Analyzing Reading Specialization Using Fmri, Rs-Fcmri, And Development, Alecia Cristen Vogel-Hammen

All Theses and Dissertations (ETDs)

Reading is an important, phylogenetically new skill. While neuroimaging studies have identified brain regions used in reading, it is unclear to what extent these regions become specialized for use predominantly in reading versus other tasks. The goal of this dissertation is to investigate the extent to which reading specialization exists at the region and network level, with a focus on orthography, the visual processing of words and letters.

I used task-based and resting state functional connectivity: rs-fcMRI) studies to investigate the specialization of orthographic processing, purportedly localized to a left occipito-temporal fusiform cortex region. In Chapter 2, we find no …

Tumor Antigens Revealed By Exome Seqeuncing Drive Editing Of Tumor Immunogenicity, Matthew David Vesely

All Theses and Dissertations (ETDs)

Accumulated data from animal models and human cancer patients strongly support the concept that immunity cannot only function as an extrinsic tumor suppressor, but also shape tumor immunogenicity. These observations led to the development of the cancer immunoediting hypothesis that stresses the dual host-protective and tumor-sculpting actions of immunity on developing cancers. We previously demonstrated important roles for lymphocytes and type I: IFN-α/β) and type II: IFN-γ) interferons in cancer immunoediting. In the present work, we confirmed the role of IFN-γ in sculpting tumor immunogenicity and provide evidence that antigens expressed by tumors drive the destructive or sculpting actions of …

Genetic And Epigenetic Interactions In In Vivo And In Vitro Reprogramming, Margaret Ashley Young

All Theses and Dissertations (ETDs)

In cancer pathogenesis and induced pluripotent stem: iPS) cell production, an essential step for reprogramming is acquisition of self-renewal. In hematopoietic cells, HOX genes are partially responsible for self-renewal, and HOX gene dysregulation commonly occurs in acute myeloid leukemia: AML). HOX dysregulation is seen in AML with translocations involving HOX genes themselves: e.g. NUP98-HOXA9) and with other disease-initiating translocations: e.g. MLL translocations and inv(16)). However, HOX genes are also highly expressed in many AML samples without translocations; the mechanism that causes "dysregulation" in these cases is unknown. Whole genome sequencing of 45 de novo AML genomes showed that recurrent mutations …

Batf3-Deficient Mice: Susceptibility To Toxoplasma Gondii And Responses To Il-12 Treatment In Vivo, Mona Mashayekhi

All Theses and Dissertations (ETDs)

CD8α+ dendritic cells are important in vivo for cross-presentation of antigens derived from intracellular pathogens and tumors. Additionally, stimulation of IL-12 production by CD8α+ DCs has suggested a role for these cells in response to Toxoplasma gondii antigens, although no experiments have yet shown an in vivo requirement for these cells against T. gondii infection. Towards this goal, we examined T. gondii infection of Batf3-/- mice, which selectively lack only lymphoid-resident CD8α+ DCs and related peripheral CD103+ DCs. Batf3-/- mice were extremely susceptible to T. gondii infection, with defective priming of CD8+ T cells, and decreased production of IL-12 and …

Monocytic Cells Mediate Granulocyte-Colony Stimulating Factor-Induced Mobilization Of Hematopoietic Stem And Progenitor Cells, Mahil Rao

All Theses and Dissertations (ETDs)

In the normal, healthy adult, hematopoiesis occurs primarily in the bone marrow. As such, at steady state, a majority of hematopoietic stem and progenitor cells: HSPCs) are tightly held within specialized areas of the bone marrow collectively referred to as the `hematopoietic stem cell niche.' In response to various forms of stress, such as infection or hemorrhage, or following administration of a variety of pharmacologic agents, niche function is altered and HSPCs are released into the peripheral circulation through a process known as mobilization. Granulocyte-colony stimulating factor: G-CSF), a hematopoietic growth factor, is the most widely-used mobilizing agent clinically. However, …

Mechanisms Of Protective Activity Of West Nile Virus Anti-Envelope Antibodies In Vitro And In Vivo, Matthew Raymond Vogt

All Theses and Dissertations (ETDs)

West Nile virus: WNV) is a neurotropic flavivirus capable of causing severe disease and death in humans. Studies in mice have demonstrated that the humoral immune response against WNV limits primary infection and protects against a secondary challenge. Accordingly, passive transfer of immune serum or monoclonal antibodies: MAb) against the envelope: E) protein either prior to WNV infection or shortly thereafter is sufficient to protect mice from disease. The E protein is an immunodominant antigen in the antibody response to WNV infection, and the most potent neutralizing MAbs recognize an epitope on the lateral ridge of domain III: DIII-LR) of …

Glucosensing, Hypoglycemia, And The Brain, Candace Reno

All Theses and Dissertations (ETDs)

Glucose homeostasis can be peripherally and centrally mediated. Within the periphery, GLUT4 in muscle and adipose tissue is required for normal glucose homeostasis and disruption of GLUT4 translocation in these tissues leads to glucose intolerance and insulin resistance, hallmarks of Type 2 diabetes. Within the brain, specialized glucose sensing neurons regulate whole body glucose homeostasis. Unlike GLUT4's role in the periphery, brain GLUT4 regulation of glucose tolerance is not well defined. Understanding how brain glucose sensing, mediated by GLUT4, regulates glucose tolerance and insulin sensitivity will aid in the development of treatment strategies to protect against the pathogenesis of diabetes. …

The Molecular Basis Of Antibody Mediated Neutralization Of Hepatitis C Virus, Michelle Catherine Sabo

All Theses and Dissertations (ETDs)

Hepatitis C virus: HCV) is positive strand, blood-borne, hepatotropic RNA virus that causes chronic infection in ~170 million people worldwide and is the leading cause of liver transplantation in the United States. HCV entry and attachment is mediated by the envelope protein E2 through interaction with several cellular receptors including CD81, scavenger receptor B1: SRB-1), claudin-1, and occludin, although the exact mechanism by which these receptors facilitate infection remains unclear, largely due to the absence of a structural model of E2. The production of neutralizing antibodies against E2 is thought to be important for controlling HCV infection, likely by blocking …