Digital Commons Network^™

Understanding The Molecular Mechanisms Of Photoferrotrophy And Phototrophic Extracellular Electron Uptake, Dinesh Gupta

Arts & Sciences Graduate Student Theses and Dissertations

Several anoxygenic phototrophs grow by utilizing soluble iron or insoluble mixed-valence iron minerals (such as rust) as electron donors to fix carbon dioxide using light energy, a process called photoferrotrophy. Photoferrotrophs can also use electron donors such as poised electrodes that serve as proxies for rust via phototrophic extracellular electron uptake (EEU). Despite the recognition that these two related microbial processes contribute to various biogeochemical cycles such as iron and carbon, the electron uptake mechanisms underlying photoferrotrophy and phototrophic EEU are poorly understood. To address the key knowledge gaps in our understanding of these microbial metabolisms, here we characterized Rhodopseudomonas …

Neural Dynamics, Adaptive Computations, And Sensory Invariance In An Olfactory System, Srinath Nizampatnam

McKelvey School of Engineering Graduate Student Theses & Dissertations

Sensory stimuli evoke spiking activities that are patterned across neurons and time in the early processing stages of olfactory systems. What features of these spatiotemporal neural response patterns encode stimulus-specific information (i.e. ‘neural code’), and how they are translated to generate behavioral output are fundamental questions in systems neuroscience. The objective of this dissertation is to examine this issue in the locust olfactory system. In the locust antennal lobe (analogous to the vertebrate olfactory bulb), a neural circuit directly downstream to the olfactory sensory neurons, even simple stimuli evoke neural responses that are complex and dynamic. We found each odorant …

Thermodynamics And Conformational Heterogeneity Of Recbcd Binding To Dna Ends, Linxuan Hao

Arts & Sciences Graduate Student Theses and Dissertations

E. coli RecBCD is crucial in initiating repair of double stranded (ds) DNA breaks. It is a heterotrimeric helicase and nuclease complex possessing two ATPase motors, RecB and RecD, and a regulatory subunit without ATPase activity, RecC. The RecB subunit also contains a 30kDa nuclease domain (RecBNuc) that, according to published structural data, is situated over 60Å away from the site of dsDNA binding. Surprisingly, we have shown in previous studies that deletion of RecBNuc to form RecBΔNucCD affects its dsDNA unwinding properties. The mechanism by which RecBNuc influences RecBCD dsDNA unwinding is unclear. In this thesis, equilibrium binding techniques, …

Genetics Of Pediatric Musculoskeletal Disorders, Lilian Antunes

Arts & Sciences Graduate Student Theses and Dissertations

Pediatric musculoskeletal disorders are an extremely broad category of diseases that are often inherited. While individually rare, collectively these disorders are common, affecting around 3% of live births in the US. Despite the mounting clinical and molecular evidence for a genetic etiology, the cause for many patients with pediatric musculoskeletal disorders remain largely unknown. Major challenges in rare pediatric diseases include recruiting large numbers of patients and determining the significance and functional impacts of variants associated with disease within individuals or families. Whole exome sequencing (WES) is a powerful tool to identify coding variants that are associated with rare pediatric …

Autologous Stem Cell-Derived Β Cells For Diabetes Cell Replacement Therapy, Kristina G. Maxwell

McKelvey School of Engineering Graduate Student Theses & Dissertations

Autologous stem cell therapy is a promising treatment for patients with diabetes worldwide. Previous stem cell-derived β (SC-β) cell protocols were unable to efficiently differentiate multiple patient induced pluripotent stem cells (iPSCs) into stem cell-derived islets (SC-islets), containing insulin-secreting SC-β cells. Recent updates targeting the actin cytoskeleton have enabled the differentiation of 14 diabetic and nondiabetic stem cell lines into SC-islets. We used genetic engineering, specifically CRISPR/Cas9, to correct the diabetes-causing mutation in stem cells from patients with Wolfram Syndrome. The genetically engineered SC-β cells functioned and had a composition similar to nondiabetic SC-β cells, unlike the unedited SC-β cells …

Structural And Functional Examination Of A Nonribosomal Peptide Synthetase Producing Β-Lactone Antibiotics, Erin Marie Gemmell

Arts & Sciences Graduate Student Theses and Dissertations

With the amount of antibiotic resistant infections increasing and the number of new antibiotics entering the pharmaceutical pipeline decreasing, the need to develop new antibiotic is imperative. Utilizing bacteria’s biosynthetic pathways for antimicrobial secondary metabolite production, would allow for unique, complex, and stereoselective compounds to be tested for novel mechanisms of action. The work described herein utilizes a β-lactone forming nonribosomal peptide synthetase (NRPS) to form a library of analogs of the nonribosomal peptide (NRP) natural product, obafluorin. β-lactones are very reactive electrophiles that can form covalent bonds with a wide range of biological targets that may provide alternative mechanisms …

Mass Spectrometry-Based Strategies In Protein Higher Order Structure Analysis: Fundamentals And Applications In Protein-Ligand Interactions, Xiaoran Liu

Arts & Sciences Graduate Student Theses and Dissertations

Protein ligand interaction is a fundamental question in biology and biochemistry, and many approaches including X-ray crystallography, nuclear magnetic resonance, cryogenic electron microscopy, mass spectroscopy (MS), infrared spectroscopy, circular dichroism, fluorescence spectroscopy and many others have been applied to address this question. Among these techniques, mass spectroscopy has the advantage of high throughput, low sample amount requirement, and mid-to-high spatial resolution. One of the MS-based approaches is protein footprinting, which utilizes labeling reagents to map the solvent accessible surface of the protein of interest thus deliver structural information. Irreversible labeling is represented by covalent labeling and radical labeling, in which …

Multifunctional Polydopamine Nanomaterials For Biomedical And Environmental Applications, Hamed Gholami Derami

McKelvey School of Engineering Graduate Student Theses & Dissertations

Polydopamine (PDA), a synthetic and organic material, has emerged as a promising materialplatform for various applications in energy, environmental, and biomedical fields. PDA, formed by self-polymerization of dopamine, is rich in catechol and amine groups, which facilitate covalent conjugation and/or other non-covalent interactions with organic and inorganic materials. It is highly biocompatible, biodegradable, has broadband light absorption spectrum and excellent light-to-heat conversion efficiency. Also, it is easy to synthesize and functionalize. The combination of excellent characteristics of polydopamine-based nanomaterials, make them a promising adsorbent agent for environmental wastewater treatment and photothermal agent for biomedical applications. In the first half of …

Developing Methods For Diversifying Molecular Scaffolds Directly On A Microelectrode Array, Nai-Hua Yeh

Arts & Sciences Graduate Student Theses and Dissertations

Microelectrode arrays contain collections of spatially isolated electrodes that can be individually addressed. Thus, the arrays have the potential to support synthesis of molecular libraries if unique members of the library can be located next to unique electrodes in the array. The result would be an intriguing platform for screening the molecules in the library against biological receptors in order to identify high-affinity ligands for those targets, especially since the arrays themselves can be directly used in the signaling studies. To expand the capabilities of the arrays, the goal of this thesis is to develop the new array chemistry needed …

Light-Directed Growth Of Semiconductor Nanomaterials By Photoelectrodeposition, Chu Qin

Arts & Sciences Graduate Student Theses and Dissertations

In this work, the chemical and physical properties of semiconductor microcrystals and metastable polymorphs were transformed through photoexcitation during electrochemical synthesis. Interfacial charge transfer using photogenerated carriers were used to successfully control the growth of metal oxide semiconductors and change their morphology, composition improve their catalytic activity. The main material systems studied in this thesis are electrodeposited copper oxide (Cu2O) and manganese oxide (MnOx) semiconductor films. Illumination can direct the shape transformation of Cu2O crystals at the nanoscale by facet-selective charge transfer. During photoelectrodeposition on Cu2O microcrystals with well-developed facets, light mediates the deposition of copper metal selectively on the …

Ascension And Adhesion Of Uropathogenic Escherichia Coli During Pyelonephritis, Lisa Kristine Mclellan

Arts & Sciences Graduate Student Theses and Dissertations

The ability of uropathogenic Escherichia coli (UPEC) to successfully establish an infection within the urinary tract relies on the pathogen to be able to navigate the complex interactions between pathogen and host. During a urinary tract infection (UTI), UPEC must ascend, adhere, and form bacterial communities in various infection niches, from the bladder (cystitis) to the kidneys (pyelonephritis). Each of these steps is critical for bacterial survival, and host and pathogen factors required at each stage can vary depending on host sex and anatomic niche. Preclinical modeling of pyelonephritis and sex effects on UTI has been limited due to the …

Refining The Characterization Of Causation In Early Childhood Neuropsychiatric Conditions: Nature, Nurture, And Time, Rachael Elizabeth Wagner

Arts & Sciences Graduate Student Theses and Dissertations

Understanding causal factors in the development of early childhood neuropsychiatric conditions is essential for an understanding of disease mechanisms and therapeutic approaches. Yet the lack of objective classification of psychiatric diagnoses, phenotypic and genetic heterogeneity, pleiotropy, and extensive comorbidity have posed immense challenges to the acquisition of knowledge regarding neuropsychiatric disease etiology. While it is unequivocally established that nearly all psychiatric conditions are substantially heritable, non-genetic factors do play a role in the development of psychopathology. This thesis explores both genetic and environmental contributors to neuropsychiatric conditions in an attempt to refine the characterization of some of these risk factors. …

Identify Rna-Associated Subcellular Localizations Based On Multi-Label Learning Using Chou’S 5-Steps Rule, Hao Wang, Yijie Ding, Jijun Tang Ph.D., Quan Zou, Fei Guo

Faculty Publications

Background: Biological functions of biomolecules rely on the cellular compartments where they are located in cells. Importantly, RNAs are assigned in specific locations of a cell, enabling the cell to implement diverse biochemical processes in the way of concurrency. However, lots of existing RNA subcellular localization classifiers only solve the problem of single-label classification. It is of great practical significance to expand RNA subcellular localization into multi-label classification problem.

Results: In this study, we extract multi-label classification datasets about RNA-associated subcellular localizations on various types of RNAs, and then construct subcellular localization datasets on four RNA categories. In order to …

Co-Phosphorylation Networks Reveal Subtype-Specific Signaling Modules In Breast Cancer, Marzieh Ayati, Mark R. Chance, Mehmet Koyuturk

Computer Science Faculty Publications

Motivation Protein phosphorylation is a ubiquitous mechanism of post-ranslational modification that plays a central role in cellular signaling. Phosphorylation is particularly important in the context of cancer, as down-regulation of tumor suppressors and up-regulation of oncogenes by the dysregulation of associated kinase and phosphatase networks are shown to have key roles in tumor growth and progression. Despite recent advances that enable large-scale monitoring of protein phosphorylation, these data are not fully incorporated into such computational tasks as phenotyping and subtyping of cancers.

Results We develop a network-based algorithm, CoPPNet, to enable unsupervised subtyping of cancers using phosphorylation data. For this …

Scientometric Profile Of The Imam Abdulrahman Bin Faisal University: A Leading University Of Eastern Province, Saudi Arabia, Md Safiqur Rahaman, Prof Isam Mohammed Abdel Magid, Shakil Ahmad Lecturer, Dr. Abu Waris Assistant Professor, Dr. Mirza Muhammad Naseer Assistant Professor, Dr Manuelraj Peter Assistant Professor

Library Philosophy and Practice (e-journal)

Purpose: The research conducted for a systematic analysis of the development and trends in scientific literature production and collaboration pattern of the faculties of Imam Abdulrahman Bin Faisal University (IAU), between 2010 to 2020 as the research productivity is one of the evaluation parameters of universities performance.

Design/methodology/approach: The study comprises the data collected from the web of science core collection (WoSCC) for the selected period. MS-Excel, MS. Access 2016, open-source software namely, Biblioshiny, ScientoPy and VOSviewer used for data analysis. The work tackled with the annual scientific research paper production, prolific authors, collaborations, most relevant sources, frequently used keywords, …

Oligodendroglial Epigenetics, From Lineage Specification To Activity-Dependent Myelination, Mathilde Mathilde Pruvost, Sarah Moyon

Advanced Science Research Center

Oligodendroglial cells are the myelinating cells of the central nervous system. While myelination is crucial to axonal activity and conduction, oligodendrocyte progenitor cells and oligodendrocytes have also been shown to be essential for neuronal support and metabolism. Thus, a tight regulation of oligodendroglial cell specification, proliferation, and myelination is required for correct neuronal connectivity and function. Here, we review the role of epigenetic modifications in oligodendroglial lineage cells. First, we briefly describe the epigenetic modalities of gene regulation, which are known to have a role in oligodendroglial cells. We then address how epigenetic enzymes and/or marks have been associated with …

Investigating The Integration-Independent Role Of Hiv-1 In In The Viral Life Cycle, Jennifer Elliott

Arts & Sciences Graduate Student Theses and Dissertations

Human immunodeficiency virus type 1 (HIV-1) relies on a handful of essential enzymes for replication. Among these, the viral integrase enzyme (IN) plays a pivotal role in the viral life cycle by catalyzing the integration of the reverse-transcribed viral DNA into the host chromosome. While integration is the canonical role of IN, new research has uncovered an additional vital role for IN during virion morphogenesis. This dissertation elucidates how IN contributes to proper packaging of the viral RNA genome (vRNA) within the viral capsid and examines the fate of improperly formed viral particles in target cells.IN is proposed to mediate …

The Role Of Mature Secretory Cells In Gastrointestinal Regeneration, Megan Deanna Radyk

Arts & Sciences Graduate Student Theses and Dissertations

Differentiated cells exhibit the ability to adjust their cell fate and become more progenitor-like after wide-scale tissue injury. This inherent cell plasticity is shown across many tissues and organisms and is a conserved behavior that ensures organ function even in a chronic injury setting. At the tissue level, the change in cell fate from a differentiated cell to one with more progenitor properties can be identified as metaplasia. Importantly, metaplasias, like Spasmolytic Polypeptide-Expressing Metaplasia (SPEM) in the stomach and Acinar-to-Ductal Metaplasia (ADM) in the pancreas, are risk factors for the development of adenocarcinoma. Thus, understanding the cellular and molecular mechanisms …

Understand And Predict Microbiome And Resistome Dynamics In Response To Perturbations Across Diverse Populations And Environments, Manish Boolchandani

Arts & Sciences Graduate Student Theses and Dissertations

Complex microbial communities are at the interface of human, animal and environment interconnected ecosystem, where they can move within and between these entities. These microbial communities are mostly beneficial, maintaining the host health and homeostatic state. However, these communities can also serve as reservoirs of antibiotic resistance (AR) genes that may disseminate to pathogen bacteria, compromising the treatment options. Like other microbial communities, human gut microbiome is highly dynamic and can get acutely perturbed with the changes in the habitat, diet, lifestyle and disease. A perturbed gut community structure has profound impact on the host health and physiology. Use of …

Contribution Of Tgf-B Signaling To The Pathogenesis Of Myeloproliferative Neoplasms, Juo-Chin Yao

Arts & Sciences Graduate Student Theses and Dissertations

TGF-b expression is increased in most cases of myeloproliferative neoplasms (MPNs); however, its contribution to disease pathogenesis is not well understood. Here, we explore two specific hypotheses. First, we hypothesize that increased TGF-b signaling in mesenchymal stromal cells contributes to the development of myelofibrosis. Second, we hypothesize that Jak2 mutated hematopoietic stem cells (HSCs) are resistant to the growth suppressive effect of TGF-b, conferring a fitness advantage that contributes to their expansion in MPNs and clonal hematopoiesis. To test the first hypothesis, we abrogated TGF-b signaling in mesenchymal stem/progenitor cells by deleting Tgfbr2 using a doxycycline-repressible Osterix-Cre transgene (Osx-Cre), which …

Examining Early Interactions Between Innate Airway Resident Immune Cells And Mtb-Specific Factors During Pulmonary Infection With Mycobacterium Tuberculosis, Micah D. Dunlap

Arts & Sciences Graduate Student Theses and Dissertations

Mycobacterium tuberculosis (Mtb) is the leading cause of death by an infectious agent in the world today, infecting roughly one quarter of humans. Despite this, the mechanisms of early pathogenesis and host protective innate immune responses remain poorly understood and uncharacterized.Lung resident Alveolar Macrophages (AMs) are the first host contact with Mtb bacilli after inhalation and are thus key mediators of the early pulmonary immune response. AMs are generally believed to reside entirely in the airway, but it was recently demonstrated that they have the capacity to egress and enter into granulomas during pulmonary infection with hypervirulent Mtb. Furthermore, we …

Understanding And Exploiting Protein Allostery And Dynamics Using Molecular Simulations, Sukrit Singh

Arts & Sciences Graduate Student Theses and Dissertations

Protein conformational landscapes contain much of the functionally relevant information that is useful for understanding biological processes at the chemical scale. Understanding and mapping out these conformational landscapescan provide valuable insight into protein behaviors and biological phenomena, and has relevance to the process of therapeutic design.While structural biology methods have been transformative in studying protein dynamics, they are limited by technicallimitations and have inherent resolution limits. Molecular dynamics (MD) simulations are a powerful tool for exploring conformational landscapes, and provide atomic-scale information that is useful in understanding protein behaviors. With recent advances in generating datasets of large timescale simulations (using …

Of Mice And Toddlers: A Cross-Species Investigation Of The Social Motivation Theory Of Autism, Claire Weichselbaum

Arts & Sciences Graduate Student Theses and Dissertations

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental condition characterized by social impairments and restricted, repetitive behaviors. Despite its growing prevalence, ASD remains poorly understood. One explanation for its social symptoms that has gained prominence in recent years is the Social Motivation Theory, which proposes a reduced motivation for social engagement as the underlying cause of impaired social functioning in ASD. While typically developing individuals find social interaction inherently rewarding, this theory suggests that people who develop ASD do not experience the same attraction to social stimuli and therefore miss out on critical social learning opportunities, hampering the development of …

Measuring And Manipulating Tension-Dependent Behavior Of Mechanosensitive Ion Channels, Angela M. Schlegel

Arts & Sciences Graduate Student Theses and Dissertations

Mechanical forces play critical roles throughout the lives of all organisms and, as such, diverse arrays of mechanotransduction systems have evolved to detect and initiate responses to force. Many mechanotransduction systems consist of mechanosensitive (MS) ion channels, membrane pores that open in response to sufficient mechanical force. My dissertation focuses on both the study and application of force-dependent conformational changes of MS channels. I tested whether charged pore-lining residues R326 and D327 of the Arabidopsis thaliana mitochondrial MS channel MSL1 function in inward rectification or gating kinetics. Mutating these residues showed no effect on MSL1 rectification; however, these residues are …

Protein Synthesis Adaptation To The Au-Rich Transcriptome Of Plasmodium Falciparum, Jessey Lee Erath

Arts & Sciences Graduate Student Theses and Dissertations

The process of protein synthesis whereby a messenger RNA is decoded into an amino acid chainis conserved among the domains. Fastidious protein synthesis is necessary for organism survival. However, exceptions negatively affecting the mRNA translation cycle – inadvertently or by design – may occur. Polyadenosine tracts are one such motif causing ribosomal stalling and frameshifting in almost all organisms tested thus far; save Plasmodium spp. Thus, with ~60% of their protein-coding genome harboring polyadenosine tracts, the elucidation of such paradigm-breaking adaptations enabling Plasmodium spp. to translate this typically problematic motif without issue is salient from both basic science and clinical …

Homeostatic T Cell Receptor Interactions With Self-Peptide Tune Cd4+ T Cell Function, Juliet Marie Bartleson

Arts & Sciences Graduate Student Theses and Dissertations

Homeostatic T Cell Receptor Interactions with Self-Peptide Tune CD4+ T Cell FunctionbyJuliet Marie BartlesonDoctor of Philosophy in Biology and Biomedical SciencesImmunologyWashington University in St. Louis, 2021Professor Paul M. Allen, ChairMature CD4+ T cells circulate throughout peripheral secondary lymphoid organs using their T cell receptor (TCR) to surveil peptide presented on major histocompatibility complex class II molecules (pMHC) in search of cognate, antigenic peptide. In the absence of an immune challenge, however, the TCR is continuously interacting with self-pMHC, which induces a relatively weak TCR signal known as tonic signaling. These homeostatic TCR:self-pMHC interactions do not propagate canonical TCR activation pathways, …

Identify Genetic And Epigenetic Abnormalities Associated With Therapeutic Vulnerability In Human Cancers, Wen-Wei Liang

Arts & Sciences Graduate Student Theses and Dissertations

Human cancer is a complex and dynamic disease with mutational, spatial, and temporal heterogeneity. There has been a concerted effort to address the heterogeneity by profiling large-scale multiomic datasets with an emphasis on abnormalities such as DNA mutations at coding regions and structural variants. However, a systematic analysis of alterations at “dark matter” is lacking – including DNA slippage events at microsatellite sequences, gene fusions arising from genomic rearrangements, and aberrant DNA methylations at promoter regions. This dissertation focus on developing data-driven computational analysis pipelines to study the patterns of microsatellite instability, gene fusions, and aberrant DNA methylation, and their …

Functional Interrogation Of Jak2 And Asxl1 Mutations In Myeloproliferative Neoplasms, Taylor Brost Collins

Arts & Sciences Graduate Student Theses and Dissertations

JAK2 V617F is the most frequent mutation found in myeloproliferative neoplasms (MPNs), with 50-60% of myelofibrosis (MF) patients harboring this mutation. Mutations in ASXL1 often co-occur with JAK2 V617F and are associated with decreased survival and increased risk of transformation to secondary acute myeloid leukemia. How mutant ASXL1 contributes to the MPN disease phenotype and confers poor prognosis is not fully understood. Asxl1 mutation knock-in mouse models present with a relatively modest phenotype, following a long latency period and ASXL1 mutations have not been modeled in combination with JAK2 V617F. The field lacks human model systems that focus on how …

Prodrug Activation In Staphylococci And The Implications For Antimicrobial Development, Justin J. Miller

Arts & Sciences Graduate Student Theses and Dissertations

Antibiotic resistance is an increasing concern for global health care, with some estimates suggesting that 10 million people will die from antibiotic resistant infections in the year 2050. Fueling this prospect, few antimicrobials are being actively developed and recently commercial entities have fled from the development of new anti-infectives. New antimicrobials and drug development strategies are urgently needed to revitalize this critical pipeline. While many putative antibiotics demonstrate promising in vitro potency, they routinely fail in vivo due to poor drug-like properties (e.g. oral bioavailability, serum-half life, toxicity) resulting in overly expensive drug development pipelines. Fortunately, drug-like properties can be …

Computational Analysis Of Non-Cpg Dna Methylation In The Mammalian Nervous System, Dennis Yawen Wu

Arts & Sciences Graduate Student Theses and Dissertations

Noncanonical forms of DNA methylation, especially non-CpG DNA methylation, play essential roles in the neuronal epigenome, and have only recently begun to be characterized. While most DNA methylation within mammals is found in a CG context and maintained by DNMT1, neurons contain uniquely high levels of non-CpG methylation, such that the total amounts of methylation in non-CpG contexts equals or surpasses the total amounts of methylation in CG contexts. Non-CpG methylation, unlike CpG methylation, cannot be maintained by DNMT1, and must be established by the de novo methyltransferase DNMT3A.One unique characteristic of non-CpG methylation compared to canonical CpG methylation is …