Molecular Biology Commons^™

Abnormal Trafficking And Processing Of Multiple Matrix Metalloproteinases Drive Cartilage Defects In Congenital Disorders Of Glycosylation, Chia-Lun Wu

All Dissertations

Congenital Disorders of Glycosylation (CDG) are rare metabolic diseases caused by defects in glycosylation. Despite identification of over 200 CDG types, the mechanisms linking glycosylation defects to diverse clinical phenotypes remain unclear. This dissertation uses zebrafish models of PMM2-CDG and STT3-CDG to redefine CDG pathogenesis, shifting from a simple glycan deficiency model to one involving disrupted cellular spatial organization.

We identify a protease-dependent pathway underlying craniofacial cartilage defects. Specifically, defective proteolytic processing of N-cadherin, a key adhesion molecule in chondrogenesis, is a central driver of pathology. We further uncover an unconventional trafficking mechanism in which ER stress and altered secretory …

Investigating The Impacts Of Azole Antifungals On Growth Of Cryptococcus Neoformans, Gnanambika Sindhe

All Theses

Cryptococcus neoformans, an opportunistic fungal pathogen is responsible for cryptococcosis, leading to approximately 181,000 deaths annually, predominantly in regions such as Sub-Saharan Africa. Fluconazole, a widely used fungistatic azole, is often administered due to its relative affordability and lower toxicity. However, resistance to fluconazole in C. neoformans can arise through aneuploidy, complicating treatment efforts. This study aims to deepen our understanding of resistance mechanisms to azole drugs by comparing fluconazole with other azoles, including both clinical and agricultural azole antifungals. Disk diffusion assays were performed to evaluate the ability of C. neoformans to develop resistance to these compounds, focusing …

Exploring Glycosomes As Therapeutic Targets For Trypanosoma Brucei, Sabrina Sutton Pizarro

All Dissertations

Trypanosoma brucei is a protozoan parasite which causes human African trypanosomiasis and the livestock wasting disease, nagana. These parasites have highly specialized peroxisomes, called glycosomes, which house a variety of essential metabolic pathways, including glycolysis. Glycolysis is the sole means of energy production in the infective life stage of T. brucei making glycosomes and the glycolytic pathway promising targets for therapeutic strategies. In this work, we have studied the glycosome as a therapeutic target from multiple perspectives. The first portion of this work addresses drug trafficking. The efficacy of small-molecule inhibitors of glycosomal enzymes is restricted by the rate of …

Elucidating The Mechanisms Underlying A Functional Plant-Arbuscular Mycorrhizal Symbiosis Using Omics Approaches, Jasmine Gill

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Arbuscular mycorrhizal fungi (AMF) are obligate biotrophs forming symbiotic association with plants. The plant-AMF symbiosis has gained much attention due to its ability to improve plant nutrient uptake, especially phosphorus, which is often inadequately available to plants due to its limited mobility and complex formation in many soils. Phosphorus (P) is a crucial nutrient for plants, and most phosphate fertilizers are derived from phosphate rock, a finite natural resource. Thus, optimizing P uptake is vital for sustaining crop yields and addressing the needs of a growing global population. Plant-AMF symbioses are significant in this context, as AMF can acquire P …

Bifunctional Fusion Protein Pdl1sfv/Micae For Cancer Immunothearpy, Junyi Li

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Cancer immunotherapy has highlighted the importance of immune checkpoint blockade and innate immune cell engagement in battling tumor-mediated immune suppression in the past few decades. However, with cancer development, advanced tumors are often found to develop resistance towards single-target immunotherapy due to the complexity of the immunosuppressive mechanisms within the tumor microenvironment (TME). To address this, we developed a novel bifunctional fusion protein, PDL1sFv/MICAe, which combines the tumor-targeting capability of an anti-PDL1 single-chain variable fragment (sFv) with the NK cells immunostimulatory properties of the MICA extracellular domain.

In vitro functional assays revealed that PDL1sFv/MICAe significantly enhanced cytotoxicity towards natural killer …

Amyloid Aggregation And Mitigation, Zhenzhen Zhang

All Dissertations

The buildup of protein in tissues and organs plays a major role in unfunctional several serious diseases, including Alzheimer’s disease, Parkinson’s disease, and Type 2 diabetes, each tied to specific proteins that form harmful amyloid deposits. Amyloid aggregation typically follows a sigmoidal kinetic curve, beginning with a slow lag phase, followed by rapid fibril growth, and eventually reaching a plateau where mature, stable fibrils are formed. However, the early stage of aggregation remains particularly difficult to capture experimentally due to the highly dynamic nature and low abundance of small oligomeric species. In this dissertation, we employed discrete molecular dynamics (DMD) …

Cross-Interactions Of Amyloid Proteins: Implications For Aggregation Dynamics And Disease Pathology, Zhiyuan Song

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Amyloid aggregation is a pervasive form of protein misfolding implicated in the pathology of several prominent human diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD), and type 2 diabetes (T2D). These diseases are marked by the accumulation of amyloid fibrils and toxic oligomers, which are highly dynamic and heterogeneous, posing challenges for understanding their roles in disease progression. Despite significant advances in the diagnosis and management of these conditions, no definitive cure is available. We investigate amyloid aggregation and cross-seeding, with a focus on amyloid-beta (Aβ), tau, alpha-synuclein (αS), and human islet amyloid polypeptide (IAPP) through discrete molecular dynamics (DMD) …

Characterizing Mechanisms Of Dna Repair And Genome Stability, Joshua Turner

All Dissertations

Every day our cells are bombarded with DNA lesions that threaten the stability of our genome. To help maintain genomic integrity our cells evolved to have a network of enzymes dedicated to repairing DNA lesions. Upon encountering a site of DNA damage, a cell recruits enzymes that remodel the stalled replication fork by reannealing the newly synthesized DNA together known as fork regression. Loss of fork regression activity has been shown to promote replication stress resistance after induced DNA damage. In this thesis, I discuss the role F-Box Helicase 1 (FBH1) plays in fork regression and how FBH1 promotes the …

Elucidating The Roles Of Septin Proteins In Thermotolerance And Cell Wall Integrity In Cryptococcus Neoformans, Stephani S. Martinez Barrera

All Dissertations

Cryptococcus neoformans is a globally distributed fungal pathogen responsible for causing cryptococcal meningitis in immunocompromised individuals. This pathogenic yeast must adapt to changes in temperature upon entering the human host. Septin proteins are conserved filament-forming GTPases that assemble as higher-order complexes at the cell cortex to support cytokinesis and morphogenesis in fungal and animal cells. In C. neoformans, four septin homologs (Cdc3, Cdc10, Cdc11, and Cdc12) assemble at the mother-bud neck, contributing to cytokinesis through poorly understood mechanisms. C. neoformans strains lacking the septins Cdc3 or Cdc12 are viable at 25°C, but fail to proliferate at 37°C, and are …

Exploring Acetate Metabolism: Genetically Characterizing Acetate Production And Acetate Utilization In The Fungal Pathogen Cryptococcus Neoformans, Rodrigo Catalan-Hurtado

All Dissertations

The basidiomycete Cryptococcus neoformans is an invasive opportunistic fungal pathogen and the most frequent cause of fungal meningitis resulting in approximately 112,000 deaths per year worldwide. Recently, the World Health Organization systematically prioritized fungal pathogens in which C. neoformans was among four fungal pathogens deemed critically important. Current methods of treatment are inadequate for most of the infected population; therefore, it is imperative to find novel therapeutic targets. Previous studies have shown that acetate is a major metabolite found in biopsies of C. neoformans infected mouse brain and lung tissues. Two potential pathways for acetate production have been identified. …

Assessment Of Tce And Chiral Pcb Dechlorination Rate, Congener Diversity, And Enantioselectivity In Town Creek, Sc, Usa Sediment Microcosms, Catherine P. Sumner

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Polychlorinated biphenyls (PCBs) and trichloroethene (TCE) are ubiquitous contaminants and are recognized as persistent organic pollutants due to their extreme chemical stability. PCBs were manufactured by chlorinating biphenyls that created 209 congeners with various structures, of which 19 are chiral and can exist as a pair of stable atropisomers. PCBs have been known to cause developmental and neurological toxicity in humans and wildlife; they can act as endocrine disrupters, carcinogens, and teratogens. Sangamo Weston Inc. was an industrial plant located near Town Creek in Pickens Country, South Carolina, that manufactured capacitors and used Aroclors 1016 and 1254 as dialectic fluids …

Evaluating Novel Approaches For Improving Anadromous Fish Passage In Coastal Rivers, Aaron Bunch

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Few of the world's rivers remain free-flowing for over 1000 km, significantly impacting anadromous fish populations due to dam-induced habitat fragmentation. Three partial migration barriers (low-head dams) on North Carolina's Cape Fear River (USA)—lock and dam 1 (LD1), lock and dam 2 (LD2), and lock and dam 3 (LD3)—impact American shad Alosa sapidissima, Atlantic sturgeon Acipenser oxyrinchus oxyrinchus, and striped bass Morone saxatilis populations. Mitigation strategies to pass fish upstream have included conservation locking, nature-like fishway construction, and environmental flows (e-flows). This study introduced a novel e-flow (dam submergence flow), tested acoustic double-tagging techniques for tracking American …

Exploring Novel Nutrient Acquisition Mechanisms For Maintaining Energy Metabolism In Toxoplasma Gondii, Melanie Key

All Dissertations

Toxoplasma gondii is an infectious intracellular parasite that establishes infection within various mammalian hosts, including humans. Toxoplasma infects approximately one-third of the global population, making it an impactful pathogen of study. T. gondii is the causative agent of toxoplasmosis, an opportunistic infection that causes severe illness or fatality in immunocompromised individuals or pregnant women. The parasite possesses a very effective invasion strategy, allowing it to cross different tissue types to disseminate infection across the placental and blood-brain barrier. Although there are a few treatments for acute toxoplasmosis, these drugs can produce adverse side effects. These options are not effective against …

Biochemical Analyses Of Udgx-A Crosslinking Uracil-Dna Glycosylase, Chuan Liang

All Dissertations

DNA base damage is common due to exposure to various endogenous and exogenous factors. To repair the base lesions, such as uracil from cytosine deamination, enzymes from the uracil-DNA glycosylase (UDG) superfamily are critical, which can recognize the damaged base and initiate the base excision repair (BER) pathway. There used to be six families of proteins identified in the UDG superfamily until a new member, UDGX, was found in Mycobacterium smegmatis, which is a unique DNA-crosslinking UDG. In this dissertation work, a series of biochemical analyses of the newly found UDGX are performed, including the analyses of structures, functions, …

Identification And Characterization Of Geotrichum Candidum Isolates From Peach With Reduced Sensitivity To Propiconazole, Sara Price

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Geotrichum candidum Link (1809) is a yeast-like fungus that causes sour rot of stone fruits, including peach (Prunus persica). The disease caused damage between 2021 and 2023 to the peach crop kept in cold storage at a commercial farm in South Carolina despite preharvest and postharvest applications of fungicides. Isolates from 41 symptomatic fruit, from a South Carolina (SC) commercial packing house, as well as other isolates obtained from South Carolina were identified to be G. candidum based on species-specific PCR amplifications of the β tubulin gene. Commonly used postharvest fungicide fludioxonil had no effect on G. candidum mycelial growth …

Biochemical And Kinetic Analysis Of Phosphofructokinase In The Eukaryotic Human Pathogen Entamoeba Histolytica, Jin Cho

All Dissertations

Entamoeba histolytica is a water- and food-borne intestinal parasite that causes amoebiasis and liver abscess in ~100 million people each year leading to ~100,000 deaths. This amitochondriate parasite lacks many metabolic pathways including the tricarboxylic acid cycle and oxidative phosphorylation, and cannot synthesize purines, pyrimidines, or most amino acids. As a result, E. histolytica is presumed to rely on its modified pyrophosphate (PP_i)-dependent glycolytic pathway for ATP production during growth on glucose. This pathway relies on a PP_i-dependent rather than ATP-dependent phosphofructokinase (PFK) and thus has a net production of three ATP per glucose. However, in …

Delineating The Impact Of Vascular Smooth Muscle Cell Abca1/G1 And Mir-33a Expression On Atherosclerosis, Olanrewaju Oladosu

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Atherosclerotic cardiovascular disease is the leading cause of mortality worldwide due to being the predominant factor in heart attack and stroke deaths. Atherosclerotic cardiovascular disease is caused by cholesterol accumulating in arteries. It is historically thought that the cell type most responsible for causing atherosclerosis via excessive cholesterol accumulation is intimal monocyte-derived macrophages. However, macrophage-like cells (MLC) of vascular smooth muscle cell (VSMC) origin have now been proposed as another cell type to trigger atherosclerosis, since VSMC cholesterol accumulation results in these cells to trans-differentiate into a MLC phenotype. Three major genes involved in cholesterol metabolism are ABCA1, ABCG1, and …

Characterization Of The Effects Of The Pyrazolopyrimidine Inhibitor Grassofermata (Nav-2729) In The Eukaryotic Pathogen Trypanosoma Brucei, Kristina Marie Parman

All Dissertations

The protozoan pathogen, Trypanosoma brucei, is the causative agent of sleeping sickness in humans and nagana in livestock in sub-Saharan Africa. T. brucei cycles between tsetse fly and mammalian hosts, and it is adapted to survive in diverse host tissues. Variant Surface Glycoprotein (VSG) plays a key role in immune evasion in the mammalian host. The VSG membrane anchor requires two myristates, 14-carbon saturated fatty acids (FAs) that are scarce in the host. T. brucei can synthesize FAs de novo, but also readily takes up exogenous FAs, despite lacking homologs to fatty acid uptake proteins found in other …

Functional Analysis Of Two Campoletis Sonorensis Ichnovirus Vinnexins In Drosophila Melanogaster, Peng Zhang

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Campoletis sonorensis Ichnovirus (CsIV) is produced by the ichneumonid parasitoid Campoletis sonorensis (the primary host). Female parasitoid wasps restrictedly replicate viruses in their ovaries and inject them into a larval lepidopteran (secondary host) during oviposition. This symbiotic virus of C. sonorensis is essential for successful parasitization. CsIV is characterized by having a large, segmented double-stranded DNA genome with a large number of genes, many of which are associated with one of five multigene families. The CsIV vinnexin gene family is one of them and has four members, including CsIV-vnxD and CsIV-vnxG. Vinnexins are homologues of insect Innexins, which form gap …

Fatty Acids And Parasitism: Towards A Better Understanding Of Lipid Metabolism In Trypanosoma Brucei, Joshua Saliutama

All Dissertations

Trypanosoma brucei is an extracellular eukaryotic parasite that causes sleeping sickness in humans and cattle. As an extracellular parasite, T. brucei relies on the host’s nutrients to satisfy its growth requirements. The parasite is unusual because it does not uptake most of the host’s lipid species. Instead, T. brucei prefers to perform de novo synthesis of most lipid species. One of the lipid species that T. brucei can both uptake and synthesize is fatty acids. In my thesis work, I investigated the dynamics of fatty acid uptake, metabolism, and utilization of T. brucei. My work starts by determining the …

Biochemical Characterization Of Ssb1, Ssb2, Sycp3, And Meilb2 In Meiotic Recombination, Garrett Buzzard

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The genome is constantly at risk to damage from environmental and normal cellular processes. Double-strand breaks (DSBs) are one of the most deleterious forms of DNA damage as unrepaired DSBs ultimately result in cell death. Homologous recombination (HR) is a conserved DNA repair pathway that utilizes a homologous chromosome as a template for DNA synthesis to repair the DSBs relatively error-free. HR is active in both mitotic and meiotic cells but meiotic HR is initiated by the introduction of programmed DSBs into the genome. The process of HR repairs the DSBs and results in a physical connection between homologous chromosomes …

Methyltransferase, Glucose Adaptation, And Import Complex In Trypanosoma Brucei, Emily Knight

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Trypanosoma brucei is a kinetoplastid parasite responsible for human African trypanosomiasis (HAT) and nagana, a livestock wasting disease, which both endemic to sub-Saharan Africa. Unique to kinetoplastids are the specialized peroxisomes, named glycosomes, which compartmentalize the first several steps of glycolysis and gluconeogenesis, nucleotide sugar biosynthesis, and many other metabolic processes. Kinetoplastids are unique in that they have a single mitochondrion. In this work, I present the first study into SET domain proteins in any kinetoplastid parasites. We have characterized a predicted SET domain protein, TbSETD3, that localizes to the mitochondrion and a depletion of the protein results in growth …

New Dna Repair And Demethylation Functions In Uracil Dna Glycosylase Superfamily, Chenyan Chang

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Uracil-DNA glycosylase (UDG) superfamily, which consists of several groups of enzymes that recognize the damaged DNA bases and initiate the base excision repair (BER) pathway, is most important in dealing with DNA deamination and other base modifications. Thymine DNA glycosylase (TDG), which belongs to family 2 in the UDG superfamily, is able to specifically recognize and cleave the 5-methylcytosine (mC) oxidative derivatives including 5-formylcytosine (fC), 5-carboxylcytosine (caC), 5-hydromethyluracil (hmU) caused by active demethylation or DNA damage. My dissertation work is mainly focused on the fC and caC glycosylase activity within UDG superfamily. Chapter 1 is a general introduction to the …

Acetate Metabolism In The Fungal Pathogen Cryptococcus Neoformans, Oly Ahmed

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Cryptococcus neoformans is an environmental basidiomycetous fungus with a worldwide distribution and a wide range of habitats. Inhalation of the desiccated yeasts or spores of C. neoformans often leads to opportunistic pulmonary infections in immunocompromised individuals, and in severe cases causes lethal meningitis following hematogenous dissemination. During infection, depending on the tissue and disease state, the invading fungi experience a range of nutrient microenvironments within the host body. As a result, rapid metabolic adaptations geared towards efficient utilization of carbon sources alternative to glucose become one of the prime determinants of survival and growth for the pathogen. Incidentally, cryptococcal infection …

Attenuation Of Human Dmc1 Recombination Activities By Substitution Of A Conserved Residue, Melody Hayman

All Theses

Unrepaired DNA double strand breaks (DSB) are detrimental to the viability of the cell. The repair of DSBs can occur by a process called homologous recombination (HR). HR is used whenever the cell has a homologous template in the way of a homologous chromosome available. The process of HR during mitosis is different from meiotic HR. To initiate meiotic recombination, DSBs are formed and processed to allow proper chromosome segregation and ultimately genetic variation. Meiotic HR is mediated by the meiosis specific recombinase, DMC1. The DMC1 recombinase binds to the 3’ end of a newly resected DSB forming a nucleoprotein …

The Role Of Vsmc Mir-33a Expression On Apoa-I Mediated Cholesterol Efflux And Macrophage-Like Cell Transdifferentiation, Ikechukwu Esobi

All Dissertations

Atherosclerosis is a condition caused by cholesterol accumulating in arterial intimal cells and is a disease that kills more people in the United States and globally than any other disease. Atherosclerosis is commonly recognized to arise from arterial intimal macrophage cholesterol accumulation, but cell lineage tracing technology has shown that a large majority of cholesterol-laden intimal cells found in atherosclerotic arteries are actually vascular smooth muscle cells that have switched phenotypes to a macrophage-like cell. This vascular smooth muscle cell to macrophage-like cell phenotypic switch is known as transdifferentiation and can be triggered by vascular smooth muscle cell cholesterol accumulation. …

Characterization Of The Wee1 Homologues And The Investigation Of Factors Promoting Cellular Enlargement In Cryptococcus Neoformans, Rodney J. Colón Reyes

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Cryptococcus neoformans is an opportunistic fungal pathogen, infecting mainly immunocompromised individuals. As the main cause of cryptococcosis, it is responsible for over 180,000 deaths every year. As an environmental yeast, it has unique adaptations that allow it to proliferate in the human host. Among these adaptations its capacity to transition to an extreme phenotype known as Titan cells is of special interest to researchers. With sizes above 10 um and able to reach 70 um or more in cell size. This size is accompanied with a large vacuole, larger polysaccharide capsule, and an increased resistance to fluconazole (FLC). FLC is …

Improved Molecular Detection Tools For The Invasive Crop Pest Helicoverpa Armigera (Hübner), Mitchell D. Rich

All Theses

Helicoverpa armigera is a major crop pest native to Europe, Asia, Australia, and Africa. H. armigera has recently invaded South America and has caused billions of dollars in agricultural losses. It is difficult to differentiate H. armigera from H. zea, a closely-related species native to North and South America. A few genetic tests have been previously developed to detect H. armigera DNA in pooled samples of moth legs. In this study, an improved qPCR melt curve assay with higher detection sensitivity and a field-based recombinase polymerase amplification (RPA) assay were developed for specific detection of H. armigera DNA …

Investigating The Biochemical Properties Of A Novel Mutation, A194v, In Human Rad51, Briana Vollbeer

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DNA double-strand breaks (DSB) are one of the most serious DNA lesions because improper repair of a DSB can lead to loss of heterozygosity, aneuploidy, and cancer. One of the primary pathways to repair DSBs is homologous recombination (HR). HR resects the DNA around the DSB and then uses homologous DNA as a template to restore the broken sequence. RAD51 has a vital function in this pathway by forming a nucleoprotein filament on a resected end of the DSB. The nucleoprotein filament searches for homology within the homologous DNA. Once homology is located, strand invasion followed by strand exchange occurs. …

Modeling Electrostatics In Molecular Biology And Its Relevance With Molecular Mechanisms Of Diseases, Mahesh Koirala

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Electrostatics plays an essential role in molecular biology. Modeling electrostatics in molecular biology is complicated due to the water phase, mobile ions, and irregularly shaped inhomogeneous biological macromolecules. This dissertation presents the popular DelPhi package that solves PBE and delivers the electrostatic potential distribution of biomolecules. We used the newly developed DelPhiForce steered Molecular Dynamics (DFMD) approach to model the binding of barstar to barnase and demonstrated that the first-principles method could also model the binding. This dissertation also reflects the use of existing computational approaches to model the effects of Single Amino Acid Variations (SAVs) to reveal molecular mechanisms …