Life Sciences Commons^™

Functional Analyses Of The Polycomb-Group Genes In Sea Lamprey Embryos Undergoing Programmed Dna Loss, Cody Saraceno

Theses and Dissertations--Biology

During early embryonic development, the sea lamprey (Petromyzon marinus) undergoes programmatic elimination of DNA from somatic progenitor cells in a process termed programmed genome rearrangement (PGR). Eliminated DNA eventually becomes condensed into micronuclei, which are then physically degraded and permanently lost from the cell. Previous studies indicated that many of the genes eliminated during PGR have mammalian homologs that are bound by polycomb repressive complex (PRC) in embryonic stem cells. To test whether PRC components play a role in the faithful elimination of germline-specific sequences, we used a combination of CRISPR/Cas9 and lightsheet microscopy to investigate the impact …

Practical Challenges In Delivering Dsrna For Woody Plant Protection, Zachary Bragg

Theses and Dissertations--Entomology

Unprecedented weather events associated with climate change, coupled with extensive anthropogenic stresses, have reduced the effectiveness of traditional forest pest management approaches, which can no longer keep pace with invasive species overwhelming naïve landscapes and native pests experiencing eruptive and expansive outbreaks. Double-stranded RNA-(dsRNA) mediated gene silencing, a type of RNA interference (RNAi), has been coopted for use as a biopesticide against a multitude of agricultural and horticultural pests and could serve as a powerful tool for woody plant protection. While effective initiation of gene silencing and subsequent mortality have been demonstrated in multiple tree pests, effective and efficient methods …

Use Of Molecular Genetics To Investigate Population Structure And Swayback In Horses, Navid Yousefimashouf

Theses and Dissertations--Veterinary Science

The present research incorporated molecular genetic methods to 1) investigate the genetic basis of Juvenile Onset Lordosis or Swayback in the American Saddlebred horses; and 2) conduct a population genetic study to compare the Persian Kurdish, Persian Arabian and American Thoroughbred horse populations.

Juvenile-onset lordosis, or swayback, is a condition in horses where the conformational topline back curvature drops significantly within the first two years of life. The trait has a higher prevalence in Saddlebreds (5%). Prior research on them quantified the trait using a Measurement of Back Contour (MBC), defining an MBC of >7.0 centimeters as swayback, and8.0) MBC …

Alzheimer’S Disease Genetics And Short-Chain Fatty Acid Treatment In Studies Of The Murine Gut Microbiome, Diana Zajac

Theses and Dissertations--Physiology

Elucidating the relationship of the gut microbiome in Alzheimer's Disease (AD) risk and pathogenesis is an area of intense interest. Since 60 to 80% of AD risk is related to genetics and APOE alleles represent the most impactful genetic risk factors for AD, their mechanism(s) of action are under intense scrutiny.

First, I conducted a study on APOE targeted replacement mice to investigate the impact of APOE alleles on the murine gut microbiome. The relative abundance of bacteria from the family Ruminococacceae and related genera increased with APOE2 status. The relative abundance of the class Erysipelotrichia increased with APOE4 status, …

Molecular Genetic Studies Of Horses, Especially With Reference To Aggrecan And Dwarfism, John Edmund Eberth

Theses and Dissertations--Veterinary Science

This work consists of studies on dwarfism in Miniature horses and a study on breakdowns in Thoroughbreds in relation to gene aggrecan. A correction of the description and designation of D3 dwarf variant in aggrecan (ACAN) from the master’s thesis Chondrodysplasia-like dwarfism in the Miniature horse (2013). Commercial sequencing showed previous sequencing reads presented an artifact and not a single base deletion. Analysis showed a single base missense mutation in exon 8 identified as D3* was the actual cause. Multiple alleles of ACAN associated with chondrodysplastic dwarfism in Miniature horses by Eberth et al. (2018), corrected the …

Placing The Evolutionary History Of Desmognathus Salamanders In Context: A Phylogeographic Approach, Kara Jones

Theses and Dissertations--Biology

Patterns of genetic variation do not arise in a vacuum but are instead shaped by the interplay between evolutionary forces and ecological constraints. Here, I use a phylogeographic approach to examine the role that ecology played in lineage divergence in the Desmognathus quadramaculatus species complex (Family: Plethodontidae), which consists of three nominal species: D. quadramaculatus, D. marmoratus, and D. folkertsi. Previous phylogenetic studies have shown that individuals from these species do not form clades based on phenotype. My approach to reconciling phylogenetic discordance was two-fold, using (1) genome-wide markers to provide insight into the …

Molecular Analysis Of Epigenetic Memory Of Stress Establishment And Long-Term Maintenance In A Perennial Woody Plant, Jia Wen Tan

Theses and Dissertations--Plant and Soil Sciences

Plants adapt to extreme environmental conditions through physiological adaptations, which are usually transient. Recent research has suggested that environmental conditions can activate a memory of stress that can result in a primed response to subsequent stress events. While the effect of priming has been observed in many plants, the underlying mechanisms are puzzling and seldom studied. A large body of research has been developed in the last decade linking response to stress, stress priming, and memory of stress with epigenetic mechanisms. This understanding of plant epigenetics has opened the door to the application of epigenetics to crop improvement, such as …

Genetic And Pharmacogenetics Associations Of Cancer Disparities In Appalachia, Nan Lin

Theses and Dissertations--Pharmacy

Individuals residing in Appalachian regions have significant health disparities, including higher cancer incidence and mortality rates. Previous studies have addressed the impact of socioeconomic status and environmental risk factors on Appalachia cancer disparities, while few studies have evaluated genetic risk factors.

Germline whole exome sequencing samples from 7,078 individuals with cancer (759 Appalachians) were evaluated. Demographics and relatedness were assessed using KING. Ethnicity was verified by principal component analysis using TRACE, which included 6,034 individuals (85%) of European genetic ancestry. After QC filtering, 5,980 individuals were analyzed. To assess the overall predisposition of hereditary disease, gene level frequency of likely …

Immunoregulatory Receptor Genetics, Expression, And Splicing Studies In Alzheimer’S Disease, Benjamin C. Shaw

Theses and Dissertations--Physiology

Microglia are the resident immune cells of the brain, undertaking many critical tissue maintenance functions such as immune surveillance and phagocytosis. Microglial dysfunction has recently been identified as a multi-stage signature of many neurodegenerative diseases, including late-onset Alzheimer’s Disease (LOAD). Genome-wide association studies (GWAS) have identified single nucleotide polymorphisms (SNPs) in over thirty genes that modulate risk of developing LOAD. In the central nervous system, roughly half of these LOAD-associated genes are primarily expressed in microglia. The proteins encoded by these genes include cell surface receptors that contain either immunomodulatory tyrosine-phosphorylated activating motifs (ITAMs) or inhibitory motifs (ITIMs), including TREM2 …

Investigating The Role Of Chd7 And Sox11 In Retinal Cell Development And The Ocular Complications Of Charge Syndrome, Laura Krueger

Theses and Dissertations--Biology

Proper formation of the visual system requires the precise interaction of several embryonic cell lineages, including the neuroectoderm (forms the retina and retinal pigment epithelium), surface ectoderm (forms the lens), mesoderm and cranial neural crest cells (form the ocular blood vessels and anterior ocular structures). When this process is disrupted structural birth defects such as coloboma result, leading to pediatric visual deficits. Ocular developmental defects are often present in larger syndromic disorders. One example is CHARGE syndrome, a genetic disorder characterized by coloboma, heart defects, choanal atresia, growth retardation, genital abnormalities, and ear abnormalities. Pathogenic variants in CHD7 have been …

Use Of Heterothallic Mat Deletion Strains Of Fusarium Graminearum As Test Mates In Crosses To Evaluate The Genetics Of Pathogenicity And Fitness, Gabdiel Emmanuel Yulfo-Soto

Theses and Dissertations--Plant Pathology

Fusarium Head Blight (FHB), caused by Fusarium graminearum sensu stricto and other members of the F. graminearum species complex (FGSC), is a plant disease that occurs on cereal crops worldwide. FHB causes yield losses not only by reducing grain weight, but also by contaminating the kernels with dangerous trichothecene mycotoxins, especially deoxynivalenol (DON). There is a high degree of genotypic and phenotypic variation among pathogen species and strains, but current FHB risk assessment models and treatments do not account for pathogen diversity. Therefore, it is difficult to predict what will happen if a new, potentially more aggressive variant is introduced, …

Identifying Epidermal Enriched Genes Required For Planarian Regeneration- Sp. Schmidtea Mediterranea, Pallob Barai

Theses and Dissertations--Biology

The outer epithelial layer covering an organism, commonly known as the epidermis, is crucial for maintaining homeostasis and for the wound healing processes after injury. The planarian epidermis allows flatworms to heal their wounds and virtually restore any missing tissues. Immediately after amputation, planarians contract their muscle and stretch their epidermis to heal the wound area. However, how the planarian epidermis coordinates with other tissues and mechanisms after the initial wound healing processes begins is not understood in detail. I hypothesized that epidermal cell stretching upon wound healing induces transcriptional changes that are required for effective regeneration. To test this …

The Role Of Nitric Oxide In Inter- And Intra- Cellular Signaling In Plant Defense, Fan Xia

Theses and Dissertations--Plant Pathology

Plants have evolved a sophisticated immune system to defend themselves against pathogens. This immune response can be triggered in response to pathogen-associated molecular patterns (PAMP) or specialized effectors that are recognized by the plant resistance (R) proteins. The latter, commonly referred to as effector-triggered immunity (ETI), is well known to induce broad-spectrum resistance throughout the plants. This phenomenon known as systemic acquired resistance (SAR) is regulated by several chemical signals including salicylic acid (SA), and free radical nitric oxide (NO) and reactive oxygen species (ROS). These signals operate in two parallel branches with NO/ROS functioning downstream of pipecolic acid (Pip) …

A Functional Genomics Approach To Overwintering Mechanisms In Insects, Emily Allison Wheeler Nadeau

Theses and Dissertations--Entomology

Insects living in temperate and polar environments have developed numerous adaptations to increase survival at low temperatures. A majority of insects are freeze-intolerant and die from internal ice formation, but some are freeze-tolerant and can survive ice formation in extracellular spaces. Both categories of insects prepare for winter with a combination of seasonal and rapid acclimation responses, which differ both in time course and in underlying mechanisms. In this dissertation, I examine adaptations for winter survival in several insect species with a specific focus on molecular mechanisms. To better understand the underpinning mechanisms of these adaptations, I leverage functional genomics …

Characterizing The Physiology And Genetics Of Contact Dependent Growth Inhibiton Systems In Burkholderia Species, Alice Elizabeth Oates

Theses and Dissertations--Microbiology, Immunology, and Molecular Genetics

Contact-dependent growth inhibition (CDI) systems mediate interbacterial competition. The genes encoding these systems are widespread among Gram-negative bacteria, including Burkholderia pathogens. CDI systems of Burkholderia species are composed of two-partner secretion pathway proteins and function to deliver the toxic C-terminus of a polymorphic surface-exposed exoprotein BcpA (Burkholderia CDI protein A) to the cytoplasm of neighboring recipient bacteria upon cell-cell contact. Specific outer and inner membrane proteins facilitate BcpA translocation both out of the donor bacterium and into the recipient cell cytoplasm. Most Burkholderia species-specific CDI translocation factors in recipient cells are unknown. BcpA intoxication functions as a mechanism by …

Cloning And Functional Characterizations Of Circular Rnas From The Human Mapt Locus, Justin R. Welden

Theses and Dissertations--Molecular and Cellular Biochemistry

Under pathophysiological conditions, the microtubule protein tau (MAPT) forms neurofibrillary tangles that are the hallmark of sporadic Alzheimer’s disease as well as familial frontotemporal dementias linked to chromosome 17 (FTDP-17). In this work, I report that MAPT forms circular RNAs through backsplicing of exon 12 to either exon 10 or exon 7 (12→10; 12→7), and that these circular RNAs are translated into proteins.

Using stable cell lines overexpressing the circular tau RNAs 12→7 and 12→10, we have discovered that the tau circular RNA 12→7 is translated in a rolling circle, giving rise to multiple proteins. This circular RNA …

Circadian Rhythmicity And Melatonin Sensitivity In The Human Gut Commensal Bacterium Klebsiella Aerogenes, Kinga Graniczkowska

Theses and Dissertations--Biology

While the expression of circadian rhythms is nearly universal among multicellular eukaryotic organisms, demonstration of this phenomenon in prokaryotes has been largely restricted to photosynthetic cyanobacteria until very recently. Further, growing interest in gastrointestinal microbiomes has revealed a complex temporal relationship between the gastrointestinal clock and the bacterial microbiome within. At least one member of the gut microbiome, Klebsiella (née Enterobacter) aerogenes, responds to the indoleamine hormone melatonin, secreted by the gastrointestinal system itself. Further research revealed that K. aerogenes also expresses a circadian rhythm in motility and gene expression that is temperature compensated. Although rhythmicity is unaltered …

Genetic Mouse Models Of Liver Disease: Potential Roles Of Zhx2 (Afr1) And Afr2 In Damage And Regeneration, Courtney P. Turpin

Theses and Dissertations--Pharmacology and Nutritional Sciences

The liver is the largest internal organ in mammals and responsible for carrying out various processes, including lipid and carbohydrate metabolism, detoxification of chemicals, and production of serum proteins. Liver damage, which can be caused by a variety of agents including viral infection, environmental toxins, alcohol and excessive dietary fats, can cause dysregulation of these critical functions, leading to worsening liver pathophysiology and impacting health. However, the liver has the remarkable ability to regenerate when damaged. Hepatocytes, which comprise a majority of liver cells, are relatively quiescent under healthy conditions. Upon injury, remaining hepatocytes can proliferate to recover from liver …

Leveraging Chemical And Computational Biology To Probe The Cellulose Synthase Complex, B. Kirtley Amos

Theses and Dissertations--Plant and Soil Sciences

Cellular expansion in plants is a complex process driven by the constraint of internal cellular turgor pressure by an expansible cell wall. The main structural element of the cell wall is cellulose. Cellulose is vital to plant fitness and the protein complex that creates it is an excellent target for small molecule inhibition to create herbicides. In the following thesis many small molecules (SMs) from a diverse library were screened in search of new cellulose biosynthesis inhibitors (CBI). Loss of cellular expansion was the primary phenotype used to search for putative CBIs. As such, this was approached in a forward …

Periocular Mesenchyme Heterogeneity During Morphogenesis Of The Vertebrate Ocular Anterior Segment, Kristyn L. Van Der Meulen

Theses and Dissertations--Biology

The vertebrate eye is a complex organ, responsible for the primary sense with which we interact with our environment: vision. Development of the eye is a tightly regulated process, controlled by a vast network of genes. This process begins with eye morphogenesis, when the eye structure is formed through a series of morphogenetic movements and culminates in the creation of the optic cup, lens, and presumptive optic stalk. Next, retinal differentiation creates the critical cell layers of the retina needed to process light waves that enter the eye, including rod and cone photoreceptors, interneurons, and support cells. Failure in either …

Leveraging Transcriptomic Approaches To Identify Differences In Genetic Programming Driving Two Distinct Wound Healing Mechanisms, Regeneration And Fibrosis, In Acomys And Mus, Shishir K. Biswas

Theses and Dissertations--Biology

Why can some animals and others cannot? This fundamental question has fueled scientists studying regeneration for hundreds of years since early observations in crayfish, salamanders and many other organisms. While most contemporary work in regeneration is done in a handful of species including salamanders, zebrafish and flatforms, these organisms lack a closely-related, non-regenerating sister species from which unique genetic differences can be identified. Additionally, while much has been learned from these organisms, they do not share fundamental biological traits with mammals (endothermy, metabolism and immune system) which limits the ability to translate this research for clinical medicine. To this end, …

Novel Computational Methods For Cancer Genomics Data Analysis, Jinpeng Liu

Theses and Dissertations--Computer Science

Cancer is a genetic disease responsible for one in eight deaths worldwide. The advancement of next-generation sequencing (NGS) technology has revolutionized the cancer research, allowing comprehensively profiling the cancer genome at great resolution. Large-scale cancer genomics research has sparked the needs for efficient and accurate Bioinformatics methods to analyze the data. The research presented in this dissertation focuses on three areas in cancer genomics: cancer somatic mutation detection; cancer driver genes identification and transcriptome profiling on single-cell level.

NGS data analysis involves a series of complicated data transformation that convert raw sequencing data to the information that is interpretable by …

Molecular Mechanisms Regulating Optic Fissure Fusion During Zebrafish Eye Development, Megan Weaver

Theses and Dissertations--Biology

Vertebrate retinal development requires timely and precise fusion of the optic fissure. Failure of this event leads to congenital vision impairment in the form of coloboma. Recent studies have suggested hyaloid vasculature to be involved in OF fusion. In order to examine this link, we analyzed optic fissure fusion and hyaloid vasculogenesis in the zebrafish pax2a noi mutant line. We first determined that pax2a^-/- embryos fail to accumulate F-actin in the optic fissure prior to basement membrane (BM) degradation. Furthermore, using 3D and live imaging we observed reduced OF hyaloid vascularization in pax2a^-/- embryos. When examining the connection …

Distribution And Diversity Of Heliothine And Other Lepidopteran Nudiviruses, Emrah Ozel

Theses and Dissertations--Entomology

Helicoverpa zea nudivirus 2 (HzNV-2) is the only known sterilizing and sexually-transmitted insect virus and causes pathological symptoms in H. zea reproductive tissues. HzNV-2 has features that make it a candidate as a H. zea (corn earworm) control agent, such as the ability to cause asymptomatic (latent) and symptomatic (lytic) infections and the ability to influence mating behavior of its host to favor virus spread. HzNV pathology has been studied and its genome sequenced, however, its prevalence in natural populations is largely unknown. In this study, we developed and used a low-cost PCR-based molecular survey to investigate HzNV-2 prevalence and …

Southern Pine Beetle-Specific Rna Interference Demonstrates No Effects On Nontarget Insects, Hannah Marie Hollowell

Theses and Dissertations--Entomology

The endemic southern pine beetle (SPB), Dendroctonus frontalis Zimmermann, is a highly destructive bark beetle that has devastated coniferous forests of the southern United States for decades. Traditional management strategies have been unable to respond effectively to largescale SPB outbreaks, prompting exploration of novel techniques including RNA interference (RNAi). Double-stranded RNAs (dsRNAs) are effective at triggering gene silencing and inducing mortality in SPB, but determining delivery methods and demonstrating specificity of the treatments is necessary before this technology may progress to deployment.

I evaluated three SPB-specific dsRNAs on model nontarget insects to assess potential lethal effects, sublethal effects such as …

Mechanisms Of Cadmium-Induced And Epidermal Growth Factor Receptor Mutation-Driven Lung Tumorigenesis, Hsuan-Pei Lin

Theses and Dissertations--Toxicology and Cancer Biology

Cadmium (Cd) is a ubiquitous pollutant in the environment and a known carcinogen for lung cancer. Cd has been shown to act as a weak mutagen, which suggests that it may exert tumorigenic effect through non-genotoxic ways, such as epigenetic mechanisms. The goal of this project is to investigate the mechanisms of Cd carcinogenesis focusing on the role of lncRNA dysregulations. The Cd-exposed cells formed significantly more colonies in soft agar, displayed cancer stem cell (CSC)-like property and formed tumors in nude mice. Mechanistically, the lncRNA microarray analysis revealed that chronic Cd exposure dysregulates lncRNA expressions. Q-PCR analysis confirmed the …

Epigenetic Implications In Inorganic Arsenic-Mediated Carcinogenesis, Meredith Eckstein

Theses and Dissertations--Molecular and Cellular Biochemistry

Chronic, low dose exposure to inorganic arsenic (iAs) is a public health concern throughout the world, contributing to the development of many diseases, including lung cancer. Several mechanisms for iAs-mediated carcinogenesis have been proposed, of which the production of reactive oxygen species and formation of chromosomal aberrations are the most studied. Another equally important, yet less studied mechanism is dysregulation of epigenetic marks. “Epigenetics” refers to changes that occur on the DNA and chromatin that do not alter base pair identity, but alter compaction, expression, and regulation of specific DNA sequences. There are several types of epigenetic marks including histone …

The Roles Of Polar Cell Extensions In Drosophila Micropyle Formation, Bradford Hull

Theses and Dissertations--Biology

The Drosophila micropyle is a conserved formation utilized to allow sperm passage past the robust eggshell structure for fertilization. Micropyle formation follows a unique acellular tubulogenesis method where it is secreted and shaped by specialized follicle cells including the border cells and polar cells. In late oogenesis, the polar cells form extensions that are necessary to create the micropyle pore through which sperm enters. Previous work established that polar cell extension presence is required for micropyle pore formation. We investigated temporal requirements of extensions throughout chorion deposition and found extensions are required during the beginning and middle of choriogenesis, but …

Combination Of Investigational Cell-Based Therapy And Deep Brain Stimulation To Alter The Progression Of Parkinson’S Disease, Nader El Seblani

Theses and Dissertations--Pharmacy

Parkinson’s disease (PD) is the second most common neurodegenerative disorder and the motor symptoms are caused by progressive loss of midbrain dopamine neurons. There is no current treatment that can slow or reverse PD. Our current “DBS-Plus” clinical trial (NCT02369003) features the implantation in vivo of autologous Schwann cells (SCs) derived from a patient’s sural nerve into the substantia nigra pars compacta (SNpc) in combination with Deep Brain Stimulation (DBS) therapy for treating patients with advanced PD.

The central hypothesis of our research is that transdifferentiated SCs within conditioned nerve tissue will deliver pro-regenerative factors to enhance the survival of …

Apoe As A Metabolic Regulator In Humans, Mice, And Astrocytes, Brandon C. Farmer

Theses and Dissertations--Physiology

Altered metabolic pathways appear to play central roles in the pathophysiology of late-onset Alzheimer’s disease (AD). Carrier status of the E4 allele of the APOE gene is the strongest genetic risk factor for late-onset AD, and increasing evidence suggests that E4 carriers may be at an increased risk for neurodegeneration based on inherent metabolic impairments. A new appreciation is forming for the role of APOE in cerebral metabolism, and how nutritional factors may impact this role. In chapter 1, the literature on nutritional interventions in E4 carriers aimed at mitigating disease risk is reviewed. Studies investigating the mechanism by which …