Genetics and Genomics Commons^™

The Genome-Wide Roles Of The Lung Lineage Transcription Factor Nkx2-1 In The Regulation Of Opposing Cell Fates In Vivo, Danielle Renae Little

Dissertations & Theses (Open Access)

Lineage transcription factors mark, promote, and maintain multiple distinct cell types originating from a common progenitor. Despite their essential role, how such factors function and bind genome wide to orchestrate the epigenetic changes necessary to form and maintain these identities in vivo is unclear. One lineage transcription factor NK Homeobox 2-1 (NKX2-1) is expressed throughout the lung epithelium during development and was thought to be lost in the extraordinarily thin cell type required for gas exchange– the alveolar type 1 (AT1) cell. Complementing precise genetic knockouts with cell type-specific ChIP-seq, ATAC-seq, and scRNA-seq, our study shows that AT1 and AT2 …

Identification And Characterization Of Novel Genes And Genetic Interactions That Influence Iba Metabolism, Vanessica Jawahir

Dissertations

Indole-3-butyric acid (IBA) is an endogenous storage auxin important for maintaining appropriate indole-3-acetic acid (IAA) levels that influences primary root elongation and lateral root development. IBA is metabolized into free IAA in the peroxisome in a multistep process similar to fatty acid β-oxidation. Although many components specific to IBA metabolism and peroxisome function have been identified, our understanding is incomplete. I sought to identify novel components of IBA metabolism or peroxisome function by conducting a forward genetic screen for Arabidopsis thaliana plants with enhanced resistance to IBA. I identified Long chain acyl-CoA synthetase 4 (LACS4) as a novel gene functioning …

Regulation Of A Messenger: Raising Oskar, It Takes A Village, Livia V. Bayer

Dissertations, Theses, and Capstone Projects

D. melanogaster oogenesis serves as an excellent system to study the life of an mRNA. Tremendous work has been done to understand the numerous complex mechanisms of mRNA regulation, still there is still so much that is yet to be discovered. In this thesis, I present studies I carried out to address several aspects of oskar mRNA post-transcriptional regulation. Leading me to extend our current understanding of the carefully controlled regulation of oskar mRNA life cycle via a myriad of proteins. I found that a specific NPC component, Nup154 is necessary not only for its export from the nucleus, but …

Characterization Of Mechanotransduction In Annulus Fibrosus Cells, Min Kyu M. Kim

Electronic Thesis and Dissertation Repository

IVD degeneration is a multifactorial pathological process associated with back pain. While biomechanical factors are important regulators of IVD homeostasis, mechanical loading also contribute to the onset of IVD degeneration. Importantly, the mechanotransduction pathways that mediate cell type-specific responses to mechanical loading are not well understood. Transient receptor potential vanilloid 4 (TRPV4) is a multimodally activated cell surface cation channel implicated as a mechanoreceptor regulating the mechano-response in other musculoskeletal cell types. Using both in vitro and in vivo models, the current study aimed to characterize the role of TRPV4 in annulus fibrosus (AF) cell mechanotransduction. Using a mechanically dynamic …

Artificial Intron Technology To Generate Conditional Knock-Out Mice, Amber N. Thomas-Gordon

Dissertations & Theses (Open Access)

Genetic engineering has been re-shaped by the invention of new tools in modern biotechnology in a way that offers precision and efficiency in modifying the genome at a single nucleotide level and/or allowing precise control of gene expression. Such gene manipulation brings about significant findings and revelations in comprehending more about embryonic development, cellular and physiological functions, and disease pathology. Current methods used to produce conditional knockouts have limitations on conditional allele placement and modification varies among genes in different organisms. Thus, a system for generating conditional alleles with fidelity remains a challenge. My goal was to examine an approach …

Probing The Limits Of Singular Gene Expression Through The Activity Of High Representation Odorant Receptor Transgenes, Eugene Lempert

Dissertations, Theses, and Capstone Projects

Singular gene expression is a common phenomenon in biology, making its appearance in immunoglobulin selection, protocadherin expression, X chromosome-inactivation, random monoallelic expression, and olfactory receptor choice. Singularity involves an activation and a feedback step. The mechanisms of singular gene choice have some capacity to integrate additional member genes while still maintaining singularity, but will activate an additional member if an earlier choice was incapable of triggering the feedback step. Odorant Receptor (OR) genes are substantially divergent from each other in terms of coding sequence, promoter structure, and genomic locus, all of which plays a role in how many Olfactory Sensory …

Gene Regulation And Cell Fate Choice In The Developing Vertebrate Retina, Sruti Patoori

Dissertations, Theses, and Capstone Projects

The diverse neuronal cell types in the vertebrate retina all originate from multipotent retinal progenitor cells (RPCs). These undergo a series of molecular changes driven by developmental gene regulatory networks (GRNs) as they divide to generate RPCs which are more restricted in their potential fates. It is crucial to understand these GRNs and changes to gene expression in order to understand how cell identity is established during retinal development. In particular, the GRN that promotes the development of cone photoreceptors and horizontal cells is not well-defined. This work focuses on two approaches to further elucidate the components of this regulatory …

Determining The Genetic Control Of Neural Tube Malformation Through Genetic Interactions With Idgf3, Elli N. Fox

Honors Projects

Genetic mutations disrupting human neural tube formation can lead to birth defects such as spina bifida and anencephaly. Defects can result in lack of neural tube closure in either the caudal (spina bifida) or cranial (anencephaly) regions. Little is known about the genes that cause these malformations. Researchers have been using the model organism Drosophila melanogaster in an attempt to determine genes responsible for neural tube malformations. Recently, an ortholog of human chitin-like protein, imaginal disc growth factor 3 (Idgf3), has been identified as important in the proper formation of Drosophila egg dorsal appendages. However, the molecular mechanism responsible for …

Fgf20 In Olfactory System And Cochlea Development, Lu Morgan Yang

Arts & Sciences Electronic Theses and Dissertations

The olfactory epithelium (OE) is a neurosensory organ required for the sense of smell. Turbinates, bony projections from the nasal cavity wall, increase the surface area within the nasal cavity lined by the OE. We identified a population of OE progenitor cells that expand horizontally during development to populate all lineages of the mature OE and increase OE surface area. We show that these Fgf20-positive, epithelium-spanning progenitor (FEP) cells are responsive to Wnt/β-Catenin signaling. Wnt signaling suppresses FEP cell differentiation into OE basal progenitors and their progeny, and positively regulates Fgf20 expression. We further show that FGF20 signals to the …

Transcriptional And Epigenetic Regulation Of Cerebellar Development And Function, Naveen C. Reddy

Arts & Sciences Electronic Theses and Dissertations

Precise control of gene expression is essential for neural development and function. This control is regulated by the interplay of chromatin remodelers and transcription factors (TFs). To better understand these mechanisms involved in gene regulation, we pursue two questions: 1) what are the roles of the chromatin remodeler CHD7 in cerebellar development and 2) what are the roles of the MEF2 TF family in cerebellar function. CHD7 mutations are causative for CHARGE syndrome, a heterogeneous disorder affecting many organ systems, occurring in 1:10,000 newborns. Recent MRI studies have identified cerebellar hypoplasia and foliation defects in a large portion of CHARGE …

Multi-Generational Effects Of ∆9-Tetrahydrocannabinol Exposure On Gene Expression In Liver Tissue, Kayla Lovitt

Honors Theses

Cannabis is the most commonly used, cultivated, and trafficked illicit drug worldwide. Increased availability and acceptance of cannabis and cannabinoid-containing products provide the necessity for understanding how these substances influence aging. In this study, zebrafish (Danio rerio) were exposed to concentrations of Δ⁹-tetrahydrocannabinol (THC) (0.08, 0.4, 2 µM) during embryonic-larval development, the effects on aging were measured 30 months later and in the offspring of the exposed fish (F1 generation. We observed results indicating a biphasic and hormetic effect. Treatment with the lowest concentration of THC significantly increased egg production, while higher concentrations resulted in impaired …

Modeling Hybrid Novel Traits: A Case Study In Complex Petal Pigment Patterning In Hybrid Mimulus, Xingyu Zheng

Undergraduate Honors Theses

Hybridization between species, by introducing dramatic trait variation into the population and creating viable, transgressive offsprings with novel phenotypes, can have huge evolutionary implications. Some hybrid traits have been studied in the classical genetics or population genetics context, but most complex traits are determined by multiple causes, e.g. the number of loci involved, the rewiring of the genetic circuitries, and the changes in gene expression pattern. Using the hybrid monkeyflower petal pigment patterning as an example, we present a case study to investigate complex hybrid traits in a systematic manner that includes empirical data analysis and quantitative mathematical modeling of …

Otx2 Represses Sister Cell Fate Choices In The Developing Retina To Promote Photoreceptor Specification, Miruna Georgiana Ghinia Tegla, Diego F. Buenaventura, Diana Y. Kim, Cassandra Thakurdin, Kevin C. Gonzalez, Mark M. Emerson

Publications and Research

During vertebrate retinal development, subsets of progenitor cells generate progeny in a non-stochastic manner, suggesting that these decisions are tightly regulated. However, the gene-regulatory network components that are functionally important in these progenitor cells are largely unknown. Here we identify a functional role for the OTX2 transcription factor in this process. CRISPR/Cas9 gene editing was used to produce somatic mutations of OTX2 in the chick retina and identified similar phenotypes to those observed in human patients. Single cell RNA sequencing was used to determine the functional consequences OTX2 gene editing on the population of cells derived from OTX2-expressing retinal progenitor …

Expression Of Tgf-Beta Ligands During Sclerotome Development, Estela Williams

Belmont University Research Symposium (BURS)

During early embryogenesis in vertebrates, somites are formed by the segmentation of the presomitic mesoderm (Gomez, Ozbudak, Wunderlich, Baumann. Lewis and Pourquie 2008). The somite possesses several domains within it and the ventral part of the somite is called the sclerotome. The sclerotome gives rise to the axial skeleton and tendons. Twist 1b and Twist 2 are genes that are expressed in the sclerotome during axial skeletal development. Our experiments were developed to help understand the roles of Twist1b and Twist2 in tendon development. By utilizing microinjection to alter gene expression, the Twist 1b and Twist 2 genes can be …

Enhancement Of Nkx3.2 Expression After Twist1b And Twist2 Knockdown In Zebrafish, Peyton Yearick

Belmont University Research Symposium (BURS)

Somitogenesis is a developmental event patterned by cellular signaling during gastrulation, ending around 30-hours post fertilization. Somites are segmented regions of mesoderm along the dorsal side of the body which form paraxial mesoderm in Danio rerio, zebrafish. Somite development results in the formation of the subcompartment called sclerotome, which differentiates to form the axial skeleton and associated tendons (Stickney et al., 2000). Further differentiation allows for sclerotome progenitor cell to develop into bone, muscle, tendon, and cartilage through sclerotome migration along the mesoderm. A portion of sclerotome cells migrate anterior towards the neural tube, where they will form the …

Using Crispr/Cas9 Gene Editing To Remove Twist2 To Determine Its Role During Somite Development In Zebrafish, Caleb Holdener

Belmont University Research Symposium (BURS)

Embryonic Mesoderm is a precursor to various types of tissues, such as the somatic mesoderm. Somites are a segmented tissue that gives rise to the sclerotome in vertebrates. This sclerotome further develops into the axial skeleton (Stickney, Barresi, and Devoto 2000). Somites are easily observable under low power microscopy during fish development. In fish, great strides have been made in studying the developmental fate of somites (Stoiber, Haslett, and Sänger 1999; Stickney, Barresi, and Devoto 2000). Zebrafish have been studied in many labs due to their similarities with higher vertebrates. These advantages include their inexpensive cost of care, external fertilization, …

Utilizing Crispr/Cas9 Gene Editing Determine The Role Of Cnr1 During Zebrafish Development, Ellis Chase

Belmont University Research Symposium (BURS)

The CRISPR-Cas 9 system is a process used to create mutations, insertions, or deletions within a desired gene. It can be used to create mutant organisms necessary to study the function and impact of a particular gene¹. Cannabinoids are active chemicals found in cannabis, the most common of which being cannabinol (CBD)². Cannabinoid receptors are an integral part of the endocannabinoid system, recognizing cannabinoid signals to promote physiological processes like pain sensation, memory, mood, and appetite³. Studying these cannabinoid receptors can provide insight into how cannabis can affect bodily processes.

Zebrafish are small translucent …

Utilizing Crispr/Cas9 Gene Editing Determine The Role Of Cnr1 During Zebrafish Development, Camme Sells

Belmont University Research Symposium (BURS)

In a world where cannabinoids are being used more frequently as for medicinal purposes, the importance for research on cannabinoid biology is steadily increasing. The goal of this study was to gain a greater understanding of the effect cannabinoids have on developing zebrafish embryos. Work in this area of developmental biology could give way to an understanding of the safety of a human fetus during pregnancy with a mother who uses cannabis medicinal therapy. The CRISPR/Cas 9 system was utilized in this study to genetically edit the zebrafish embryo genome to remove the function of the Cannabinoid Receptor 1 ( …

Scleraxis Expression Within The Axial Tendon Population In Zebrafish, Jessica Bernaba

Belmont University Research Symposium (BURS)

Zebrafish are a well-established model organism for vertebrate development. During embryonic development, a pattern of segmentation of mesoderm yields somites, which give rise to specific cell fates. Somites, bilateral blocks of mesoderm along the neural tube in developing vertebrate embryos, subdivide into sclerotome as the vertebrate matures. Depending on migratory position, sclerotome cells give rise to various components of the axial skeletal system, including bone, cartilage, and tendon. Each fate is determined by gene expressions within the sclerotome and occupy distinct domains of the body plan. By method of in situ hybridization, we studied the expression of the scleraxis ( …

Exploring The Role Of Tgfbr2 During Zebrafish Sclerotome Development, Nooralhuda Feron

Belmont University Research Symposium (BURS)

Zebrafish, Danio rerio, are used as a source model organism for human development of the tendons, bones, and ligaments. The sclerotome is an embryonic structure known as the somite. The sclerotome gives rise to axial bones and tendons. During development, different genes are involved and affect how these skeletal tissues develop. Specifically, within this project, the effects of Twist1b and Twist2 were studied to see their effects on tendon formation, as they are expressed within the developing sclerotome tissue. Transforming growth factor beta receptor type-2 (Tgfbr2) has been shown to be involved in tendon formation (Subramanian, Kanzaki, Galloway and …

Twist1b Knockout Generation In Zebrafish Using Crispr-Cas9, Grace Hurley

Belmont University Research Symposium (BURS)

The Twist gene is found in numerous organisms, including humans, mice and zebrafish (Yeo et al., 2009). It is a vital gene in development and is needed for the organism to survive (Yeo et al., 2009). Specifically, the Twist gene family aids in specialization and differentiation of mesodermal cells, telling somites, segmented blocks of mesoderm, what to become (Germanguz et al., 2007). Over time, the Twist gene has duplicated into paralogs, each having differences in their functions (Germanguz et al., 2007). Twist1b is a protein coding gene that is a paralog to the human Twist1 gene (ZFIN, 2020). In zebrafish, …

Thyroxine-Dependent And -Independent Effects On Premature Aging And Myelination In Atrx Mutant Mice, Megan E. Rowland

Electronic Thesis and Dissertation Repository

ATRX is an ATP-dependent chromatin remodeler required to safeguard genomic integrity. Conditional deletion of Atrx in the mouse embryonic forebrain and anterior pituitary in Atrx^Foxg1Cre mice phenocopies mouse models of progeria which display increased DNA damage, coupled with reduced lifespan, growth and subcutaneous fat. These mice also have severely low circulating levels of insulin like growth factor 1 (IGF-1) and (T4) which have been reported in models of premature aging. Based on evidence that Igf1 is activated by the ligand-bound thyroid hormone receptor, I tested whether T4 supplementation could restore IGF-1 levels and ameliorate premature aging phenotypes in Atrx …

Mushroom Body-Specific Gene Regulation By The Swi/Snf Chromatin Remodeling Complex, Kevin Cj Nixon

Electronic Thesis and Dissertation Repository

Over the lifetime of an organism, neurons must establish, remodel, and maintain precise connections in order to form neural circuits that are required for proper nervous system functioning. Disruptions in these processes can lead to neurodevelopmental disorders such as intellectual disability (ID) and autism spectrum disorder. Mutations in genes encoding subunits of the SWI/SNF chromatin remodeling complex have been implicated in ID, yet the role of this complex in neurons is poorly understood. In this project, I established cell-type specific methods to examine the effect of SWI/SNF subunit knockdowns on gene transcription and chromatin structure in the memory-forming neurons of …

Gene Expression Pattern Analysis Of Anterior Hox Genes During Zebrafish (Danio Rerio) Embryonic Development Reveals Divergent Expression Patterns From Other Teleosts, Adam Davis

Georgia Journal of Science

The regional identity of organs and organ systems along the anterior-posterior axis during embryonic development is patterned, in part, by Hox genes, which encode transcription factor proteins that activate or repress the expression of downstream target genes. Divergent nested Hox gene expression patterns may have had a role in facilitating morphological divergence of structures, such as the pharyngeal jaw apparatus, among evolutionarily divergent teleost fishes. Recent studies from several evolutionarily divergent teleosts, such as the Japanese Medaka (Oryzias latipes) and the Nile Tilapia (Oreochromis niloticus), have shown the presence of divergent expression patterns of several Hox …

In Situ Analysis Of Line-1 Promoter Activity Using Lacz Transgenic Mice, Partha Sarathi Saha

Electronic Theses and Dissertations

Apart from an evolutionary role, transposable elements have been implicated in animal development and also in pathophysiology. Non-LTR retrotransposons– LINE-1, Alu and SVA - are responsible for over 120 cases of human genetic diseases as heritable insertions, and are emerging as an important etiological factor for cancer and neurological disorders as somatic mutations. It is estimated that among the total number of 500,000 LINE-1s presents in the human genome, 80-100 LINE-1s remain competent for retrotransposition. Retrotransposition is only possible when LINE-1 is expressed. Because LINE-1 transcription is regulated by its 5’UTR promoter, it is essential to understand the spatiotemporal control …

Dispelling The Mirage Of C4-Driven Drought Tolerance In Poaceae: A Phylogenomic Study, Matthew P. Nissenbaum

Graduate Research Theses & Dissertations

Climate change has been considered a key driver for adaptations in water usage efficiency (WUE) in plants. Perceptions persist that C4 photosynthesis is indicative of some level of WUE. Here, we examined the interaction and evolution of WUE within the grass family, Poaceae, as it pertains to photosynthetic pathway. Unique to this study is the magnitude of taxa sampled, presence of intrageneric sampling, and use of complete plastid genomes (plastomes) for phylogenomic analyses.

310 species were sampled, including 26 with newly sequenced plastomes, which were assembled de novo from next-generation sequencing data. Additional plastomes were downloaded from the National Center …

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 …

Developmental Mechanisms For The Diversification Of Polyphenic Morphs In The Head Horn Of Onthophagine Beetles (Coleoptera: Scarabaeidae Onthophagus Taurus): Plasticity Through Nutrition, Logan Paul Zeigler

Graduate Theses, Dissertations, and Problem Reports

Developmental plasticity is the phenotypic variation between organisms that is caused by environmental interactions affecting the developmental systems of organisms. The research focused primarily on nutrition-responsive developmental plasticity. In this research we used the nutritionally determined head horn development of Onthophagus taurus to better understand the developmental mechanisms and genetic underpinnings of nutrition-responsive trait development. We focused specifically on altering the availability of specific nutrition-related primary metabolites, cholesterol and palmitic acid, identified in the activity of The Hedgehog pathway, a critical pathway in head horn development. By altering diet composition using cholesterol, reducing transcript expression of an acyltransferase gene, rasp …

The Effects Of Internal Physiology On Polyphenic Horn Development In The Dung Beetle Onthophagus Taurus, Naomi Garrett Williamson

Graduate Theses, Dissertations, and Problem Reports

An organism’s phenotype can be affected in development by alterations to gene expression based on environmental inputs. Nutrition is one such environmental input and the central regulator of development of large horn or small horn phenotypes in the dung beetle species, Onthophagus taurus. However, little is known about the nature of chemical compounds that are critical to this plastic horn development. To better understand these compounds, we are utilizing an untargeted metabolomic approach as well as a targeted gene approach. Through the metabolomic approach, it was uncovered that environmental conditions tend to have a greater impact on metabolomic composition …

Development And Validation Of Gene Delivery Methods For ​Crassostrea Virginica, Adrienne N. Tracy

Honors Theses

The Eastern oyster (Crassostrea virginica) is an important part of the East Coastal USA economy because aquaculture creates jobs. Sadly, the oysters are under constant threat due to increasing pollution, red tides, and diseases. Bivalves, and oysters in particular, are also becoming potential model organisms in medical research. With the sequencing of the oyster genome, scientists are focusing on deciphering the function of the predicted genes. However, the limited number of molecular and cellular tools available makes functional annotation of the genome challenging. A consistent, replicable gene delivery system needs to be developed to assess gene function and understand the …