Life Sciences Commons^™

Atypical Protein Kinase C Dependent Polarized Cell Division Is Required For Myocardial Trabeculation, Derek L. Passer

Theses & Dissertations

A hallmark of cardiac development is the formation of myocardial trabeculations exclusively from the luminal surface of the primitive heart tube. Although a number of genetic defects in the endocardium (Grego-Bessa et al., 2007; Liu et al., 2010) and cardiac jelly (Camenisch et al., 2000) disrupt myocardial trabeculation, the role of cell polarity machinery in driving this process remains unclear. Herein, we demonstrate that atypical protein kinase C iota (Prkci) and its interacting partners of Par polarity complex are localized to the luminal side of luminal myocardial cells. Remarkably, a subset of these cells undergoes polarized cell division with the …

The Role Of Bone Sialoprotein In Periodontal Tissue Development And Bone Repair, Yohannes Soenjaya

Electronic Thesis and Dissertation Repository

Bone development and repair involve complex processes that include interaction between cells and their surrounding matrix. In the body, bone sialoprotein (BSP) expression is up-regulated at the onset of mineralization. BSP is a multifunctional acidic phosphoprotein with collagen-binding, hydroxyapatite nucleating, and integrin recognition (RGD sequence, which is important for cell-attachment and signaling) regions. Mice lacking BSP expression (Bsp^-/-), exhibit a bone phenotype with reductions in bone mineral density, bone length, osteoclast activation, and impaired bone healing. This thesis examined the role of BSP in tooth development and also its potential use as a therapeutic reagent for bone …

Effects Of Global Dna Methylation Changes On Neurobehavior In Zebrafish, Matthew Christopher Pickens

Theses and Dissertations

A number of environmental neurotoxicants modulate DNA methylation, but its influence on neurobehavior remains unclear. The laboratory has established that low-level developmental methylmercury exposure induces neurobehavioral deficits; the current results demonstrate that it also induces global DNA hypomethylation. DNA methyltransferase 1-mutant zebrafish (exhibit ~70% reduction in enzymatic activity) were used to assess the role of DNA hypomethylation on behavior. Several neurobehavioral assays including the C-start escape, circadian rhythm, basic locomotion and visual-motor response (VMR) were also performed. There was a significant difference in VMR between the wild type and mutant animals. Other behavior assays revealed no significant difference, primarily due …

Defining The Molecular Networks Necessary For Thymus Fate And Organogenesis, Kaitlin A. Reeh

Dissertations & Theses (Open Access)

The thymus and parathyroid (PT) glands originate from endodermal progenitors in the bilateral third pharyngeal pouches (3^rd pps). By E11.5 during mouse development, cells committed to the thymus lineage express Foxn1 whereas PT-fated cells express Gcm2. While these transcription factors are required for organ-specific differentiation, the exact molecular mechanisms that specify endodermal progenitors to either the thymus or parathyroid lineage are not well defined. Tbx1 is initially expressed throughout the 3^rd pp endoderm, as it is required for segmentation of the pharyngeal apparatus, but is downregulated in the thymus-fated domain by E10.5. Despite the widely held notion …

Problem Solving Skill And Obesity In Children, Caitlin R. Spano

The Eleanor Mann School of Nursing Undergraduate Honors Theses

Abstract:

Introduction: Childhood obesity is a problem that leads to many serious health effects including early maturation, decreased quality of life and increased risk for cardiovascular disease. In 2012, over one third of children were considered obese (Childhood Obesity Facts 2015). Efforts have been made to reduce this number but they have not been fully successful (Nutrition Standards for School Meals 2015, Prevalence of Childhood obesity in the United States 2011-2012 2015). What other factors are causing kids to choose foods that lead to weight gain.

Literature Review: In research regarding psychological motivations of overeating, there has been a correlation …

Characterization Of The Role Of Intrinsic And Extrinsic Factors During Murine Endoderm Development, Siyeon Rhee

Doctoral Dissertations

Yin Yang1 (YY1) is a ubiquitously expressed factor that plays multiple roles in early mouse development. We have found that an essential role of YY1 in the visceral endoderm (VE) of the yolk sac is the maintenance of VEGF. Furthermore, we have demonstrated that paracrine signals downstream of VEGF support the VE, assessed by maintenance of HNF4α. Because the VE is essential for yolk sac development, and thus for embryonic survival, we used an inducible-knockout strategy to demonstrate that YY1 is essential in the definitive endoderm (DE) for invasion of hepatoblasts into the surrounding mesenchyme. By E14.5 YY1-/- livers are …

Uncovering New Roles For The Cell Surface Protease Adam13 In Neural Crest Migration, Genevieve Abbruzzese

Doctoral Dissertations

ADAMs are a family of transmembrane metalloproteases that control cell behavior by cleaving both cell adhesion and signaling molecules. They play a variety of roles in diverse tissue types during development and can affect cell processes such as migration, differentiation, growth and survival. In the embryo, several ADAMs have proven to be integral components of the cranial of neural crest (CNC), which is a multipotent population of cells that gives rise to multiple structures of the face and head. These cells are highly motile and undergo a large-scale migration throughout the embryo that is essential for proper craniofacial development. The …

Behavioral And Neural Mechanisms Of Impulsive Choice, Jesse Mcclure

Doctoral Dissertations

Impulsive choice is defined as the preference for a small immediate reward over a larger delayed reward. Individual variablity in impulsive choice correlates with many socially relevant behaviors. Although forms of impulsive choice have been studied in both behavioral ecology and psychology, the exchange of knowledge between these fields is just beginning. Drawing from both of these fields will improve our research methods allowing for a more detailed understanding of this complex behavior. Existing tasks to measure impulsive choice conflate the delay and quantity of the reward. To address this, I have drawn from foraging research to establish a method …

Cardiomyocyte Polarity And Embryonic Heart Development: Role Of Rac1, Carmen Leung

Electronic Thesis and Dissertation Repository

Congenital heart defects (CHDs) are the most common human birth defect and the leading cause of death from a birth defect in the first year of life. Thus, a further understanding of the mechanisms underlying CHDs, which could lead to improved diagnosis and treatment, is crucial. The small GTPase, Rac1, acts as a pleiotropic effector of numerous cellular processes; however, little is known about its role in embryonic heart development. The aim of this thesis was to investigate the role of Rac1 signaling in cardiac development. Using the Cre/loxP system, mouse models with an anterior second heart field (SHF) or …

Dna Repair Deficiency In Huntington's Disease Fibroblasts And Induced Pluripotent Stem Cells, Peter Anthony Mollica

Biological Sciences Theses & Dissertations

Mutant huntingtin protein (mhtt)– the protein responsible for cellular dysfunction in Huntington’s disease (HD) –is a product of an expanded trinucleotide repeat (TNR) cytosine-adenine-guanine (CAG) sequence in exon 1 of the huntingtin (HTT) gene. The pathology of HD has been extensively researched; however, the mechanism by which the disease-causing TNR expansions occur in somatic cells remains elusive. Interestingly, HD has often been referred to a ‘DNA repair disease’, even though DNA repair dysfunction in situ has not been identified. We hypothesized that presence of the mhtt protein affects the expression of DNA repair genes used to address DNA repair, ultimately …

Wnt Signalling During F9 Cell Differentiation, Gregory M. Golenia

Electronic Thesis and Dissertation Repository

Mouse F9 cells differentiate into primitive endoderm (PrE) when treated with retinoic acid (RA) and this is accompanied by the upregulation of Wnt6 and activation of the canonical WNT/β-catenin pathway. Previous studies have demonstrated the necessity of β-catenin-TCF/LEF transcription for primitive endoderm differentiation, however the Frizzled (FZD) receptor responsible for binding WNT6 and activating the canonical WNT pathway is not known. It was hypothesized that FZD7 is responsible for binding and transducing the WNT6 signal. Fzd7 mRNA was detected in undifferentiated and primitive endoderm cells, and its expression does not change significantly in response to RA. Moreover and contrary to …

Investigating Hox Protein Requirement For Tarsus Determination In Drosophila Melanogaster, Samantha Koot

Electronic Thesis and Dissertation Repository

Generally, all bilaterans examined have similar conservation of HOX protein structure, function, expression, and requirement. However, at the level of being the same, it is unknown whether the HOX protein, Antennapedia, is required for tarsus determination in Drosophila melanogaster as in Tribolium casteneum, or whether the requirement of HOX proteins in determination of body parts diverges in insects. I proposed to use a heat shock-inducible nanobody (UAS- NSlmb-vhhGFP4 driven by hsp-GAL4) activated during the third larval stage in all cells to degrade thoracically expressed HOX proteins (Sex combs reduced, Antennapedia, and Ultrabithorax) tagged with green fluorescence protein …

Interactions Between The Hypothalamic-Pituitary-Adrenal (Hpa) Axis, Oxytocin System, And Behavior In Differently Reared Rhesus Monkeys (Macaca Mulatta), Amanda F. Hamel

Doctoral Dissertations

Adverse experiences that occur during early critical periods of development modify activity of neuroendocrine systems, such as the hypothalamic-pituitary-adrenal (HPA) axis and oxytocin system. This dissertation examines the effects of nursery rearing, an established model of adverse early experiences, on activity of the HPA axis and oxytocin system in infant and adult rhesus macaques (Macaca mulatta). In addition, influence of oxytocin system activity on the HPA axis and behavioral reactivity was examined. In infant monkeys, nursery-rearing was associated with lower HPA axis, yet higher oxytocin system activity, following the acute stress of developmental assessment. Nursery rearing may result …

The Role Of Connexins And Pannexins In Mammary Gland Development And Tumorigenesis, Michael K. G. Stewart

Electronic Thesis and Dissertation Repository

The identification of key regulators of breast cancer onset and progression is critical for the development of targeted therapies. Connexins and pannexins are characterized by their ability to form large-pore channels and are frequently dysregulated in cancer. However, their role in breast cancer progression remains poorly understood due to a lack of in vivo models capable of assessing the proposed and opposing roles of connexins and pannexins as both tumor suppressors and/or facilitators in multiple stages of the disease. Using 2 previously uncharacterized genetically-modified mice, connexin43 (Cx43) and connexin26 (Cx26) were evaluated for their role in normal mammary gland development …

Maternal Nutrient Restriction In Pregnant Guinea Pigs Impacts Fetal-Placental Growth And Oxygenation, Alexander Elias

Electronic Thesis and Dissertation Repository

Maternal nutrient restriction (MNR) in guinea pigs results in placental structural abnormalities that reduce nutrient transport contributing to fetal growth restriction (FGR). However, whether fetal oxygenation is also reduced as a further mediator of altered growth and development remains unknown. Guinea pig sows were fed ad libitum (Controls) or 70% of the control diet pre-pregnant switching to 90% at mid-pregnancy (MNR). Animals were necropsied near term for fetal-placental growth measures, blood metabolites, and markers of tissue hypoxia and oxidative stress. MNR resulted in FGR with brains that are large and livers that are small relative to body weight which suggests …

Functional Characterization Of The Roles Of Endocytic Recycling Regulator Ehd1 Using In Vivo And In Vitro Analyses, Priyanka Arya

Theses & Dissertations

Endocytic recycling is a fundamental cellular process that allows the precise regulation of the membrane components and receptors at the cell surface. Recent studies have established that the C-terminal Eps15 homology domain-containing (EHD) proteins function as key regulators of this process. Four highly-conserved members of the EHD protein family in mammals, EHD1-EHD4, play shared as well as unique roles in endocytic trafficking. Studies presented here demonstrate a critical role of EHD1 in the normal ocular development in mice. Ehd1 knockout mice generated in our laboratory displayed gross ocular phenotypes including the anophthalmia, microphthalmia, and congenital cataracts. Hematoxylin and eosin (H&E) …

Characterization Of The Nicotine-Induced Endoplasmic Reticulum Stress Response In The Rat Placenta In Vivo And In Vitro, Michael Ka Chun Wong

Electronic Thesis and Dissertation Repository

Nicotine exposure during pregnancy leads to adverse health outcomes, including compromised placental development. Although the molecular mechanisms remain elusive, recent studies identified that endoplasmic reticulum (ER) stress may underlie poor placentation. Therefore, we were interested in investigating the effects of nicotine exposure on the ER stress response in the placenta. A well-established maternal nicotine exposure rat model and Rcho-1 trophoblast giant cell model were utilized to address the research questions. Maternal nicotine exposure in vivo led to elevated ER stress in association with impaired disulfide bond formation and hypoxia. Nicotine exposure in vitro further differentiated that ER stress may be …

Investigation Of Pancreatic Β-Cell Insulin Receptor Regulation Of Β-Cell Growth, Function, And Survival Via A Temporal Conditional Knockout, Liangyi Zhou

Electronic Thesis and Dissertation Repository

The expression of insulin receptor (IR) in β-cells suggests an autocrine role for insulin signalling in β-cell function and regulation. Studies have demonstrated that β-cell Ir knockout (βIrKO) mice develop age-dependent glucose intolerance. We investigated the temporal role of β-cell IR signaling in pre- and postnatal islet development and function, and under high-fat diet stress, using a tamoxifen-inducible Cre-recombinase Ir knockout mouse model.

Prenatal βIrKO mice exhibited increased mean islet area, β-cell area, and islet area percentage. Additionally, there was upregulation of insulin-like growth factor-2 levels, increased Akt activity, and increased proliferation in islets. Postnatally-induced βIrKO mice did not exhibit …

Microengineering The Neural Tube, Christopher Demers

Electronic Theses and Dissertations

Early embryonic development is a complex and highly regulated orchestra of instructive cues that collectively guide naïve stem cells towards progressively more specialized fates. In the neural tube, the precursor structure to the brain and spinal cord, these signals emanate from ‘organizing centers’ surrounding the neural tube. These organizing centers send out soluble cues or morphogens that diffuse tens to hundreds of microns to recipient cells residing in the neural tube. Re-creating this dynamic landscape of cues in vitro is impossible using standard cell culture tools and techniques. However, microfluidics is perfectly suited to fill this gap, allowing precise control …

Calmodulin-Like Protein 38: A Component Of Ribonucleoprotein Particles During Hypoxic Stress Responses In Arabidopsis, Ansul Lokdarshi

Doctoral Dissertations

Waterlogging stress leads to a crisis in energy metabolism and the accumulation of toxic metabolites due to the hypoxic and/or anoxic environment associated with this condition. To respond and adapt to this situation, higher plants employ an integrated genetic program that leads to the induction of anaerobic response polypeptide genes that encode metabolic and signaling proteins involved in altering metabolic flow and other adaptive responses. The study presented here shows that the Arabidopsis thaliana calmodulin-like protein CML38 is calcium sensor protein that serves as a member of the core anaerobic response gene family and is involved in modulating the survival …

The Effects Of Triiodothyronine, Glucose, Alanine, And Iodide As Nutrients On The Survival And Successful Metamorphosis Of Aeolidiella Stephanieae Veligers, Bryan Tate

All Theses And Dissertations

During early life stages, nutrients are crucial to the proper development of larval marine invertebrates. Many such larvae are lecithotrophic and therefore do not actively feed; however, a large body of research has shown that lecithotrophic larvae take in dissolved organic material (DOM) including amino acids and sugars, contributing heavily to metabolic requirements. Another dissolved nutrient, iodine, is useful to marine invertebrates for the production of organic compounds. Some of these compounds (thyroid hormones, THs) are historically thought to be used almost exclusively by vertebrates, though studies have shown that THs are also useful to some marine invertebrates for developmental …

Merlin Mediated Regulation Of Hair Follicle Morphogenesis, Megan K. Fentress

Dissertations & Theses (Open Access)

Epidermal homeostasis is paramount for the ongoing function of the skin as the primary barrier between a mammalian organism and the external environment. Homeostasis is achieved through a complex and delicate balance of cell death, cell proliferation and cell differentiation. Critical for regeneration and maintenance of the skin are epidermal stem cells. Within the epidermis two distinct stem cell compartments exist, the bulge and interfollicular/basal stem cell niches, which play a central role in the regeneration of the epidermis through self-renewal and contribution to the differentiated cells of the epidermis. The bulge stem cell niche is established early in epidermal …

The Ctcf Chromatin Organizer Is Required For Hindlimb Development, Katherine L. Rabicki

Electronic Thesis and Dissertation Repository

Mutations in chromatin organizer CTCF were identified in patients with intellectual disability and skeletal defects. Previous studies demonstrated that depletion of CTCF in murine limb mesenchyme results in apoptosis in the forelimb. The role of CTCF in the hindlimb, however, is unknown. My objective was to investigate effects of CTCF deletion on chondrogenesis and skeletal development in the hindlimb. In vitro wild-type micromass cultures demonstrate that chondrocyte gene expression is delayed in the hindlimb when compared to forelimbs. Embryonic Ctcf^Fl/Fl;Prx1Cre mice were investigated, and qRT-PCR and histology were performed on limb buds and long bones. Results show that …

Characterization Of The Role Of Alpha-Arylphorin In The Heliothis Virescens Midgut Response To Cry1ac Toxin From Bacillus Thuringiensis, Jerreme Jamael Jackson

Doctoral Dissertations

Homeostasis of the intestinal epithelium in Heliothis virescens is mediated by the proliferation and differentiation of multipotent intestinal stem cells (ISCs) that lie adjacent to the basal lamina. In response to extrinsic and intrinsic signals, ISC proliferation and differentiation promotes epithelial growth and regeneration following the loss of integrity. We tested the in vivo effects of the ISC mitogen, a [alpha]-arylphorin, on ISC proliferation and the morphological changes of the midgut during larval development. Additionally, we examined how these changes affected the intestinal epithelium response to Cry1Ac toxin from Bacillus thuringiensis. Histological and in vitro evidence supported two distinct …

Impact Of Differentiation Status Of Kidney Progenitors In Wilms Tumor Development, Le Huang

Dissertations & Theses (Open Access)

Wilms tumor is one of the most common solid tumors in children. It is an embryonic cancer of the kidney and is thought to arise from undifferentiated renal mesenchyme. However, the differentiation status of cells in the mesenchyme that can give rise to Wilms tumors is unknown. Gene expression analysis of a large panel of Wilms tumor patients has identified different subsets of Wilms tumors that are distinct in their clinical outcomes and gene expression signatures. These subsets express specific genes that correspond to different stages of differentiation during renal development, suggesting that Wilms tumors may arise from transformed cells …

Descriptive Analyses Of Pollen Surface Morphologies In The Model Systems Brassica Rapa And Arabidopsis Thaliana And Three Arabidopsis Pollen Wall Mutants By Scanning Electron Microscopy, Andrew B. Kirkpatrick

Theses and Dissertations

The mechanisms behind the construction of the pollen wall are equally elaborate and mysterious. Previous studies primarily used sectioned tissue to elucidate the events involved in proper pollen development. This study proposed and evaluated a protocol for exposing developing microspores to be examined by Scanning Electron Microscopy (SEM). Utilizing this protocol, comparative analyses of the superficial features present at the early, middle, and late tetrad as well as at released microspore stages of the model plants Brassica rapa and Arabidopsis thaliana were conducted. The utility of the technique was then evaluated through the examination of three Arabidopsis pollen wall mutants …

Efficient In Vitro Development Of Photoreceptors From Human Pluripotent Stem Cells, Joseph C. Reynolds

Dissertations, Masters Theses, Capstones, and Culminating Projects

Degeneration of the rod and cone photoreceptors in the human retina is among the most common causes of blindness. Replacing these damaged photoreceptors may help to restore vision. Repairing the damaged retina relies on the insertion of new, healthy cells. Embryonic stem (ES) cells and induced pluripotent stem (iPS) cells are two possible sources of photoreceptors to restore vision. Previous data shows that human ES cells and iPS cells can be differentiated into photoreceptors and transplanted into the eye to restore some vision. However, this process is inefficient, and costly. Here, we show a new method for inducing photoreceptor production …

Deciphering The Functional Collaboration Of Mid And Bric-A-Brac 2 As Potential Regulators Of Cellular Proliferation Within Adult Drosophila Ovaries, Petra Visic

Master's Theses

Stem cell niches are highly organized and specialized microenvironments located within specific tissues of both vertebrate and invertebrate organisms [1]. In Drosophila melanogaster, three distinct stem cell niches have been identified within the ovary including the germline stem cell (GSC), follicle stem cell (FSC), and escort stem cell (ESC) niche. Recently, Fregoso-Lomas et al. [2] reported that Gurken/Epidermal Growth Factor Receptor (EGFR) signaling is modulated within posterior ovarian follicle cells by Midline (Mid). The mid gene encodes a T-box transcription factor protein that specifies cell fates in the developing heart [3][4], central nervous system [5][6], epidermis [7], and eye …

Understanding The Evolution Of Aggregative Multicellularity: A Molecular Phylogenetic Study Of The Cellular Slime Mold Genera Sorodiplophrys And Pocheina, Alexander Tice

Graduate Theses and Dissertations

Cellular slime molds are amoeboid protists that have a unicellular trophic phase and multicellular dispersal stage formed through the aggregation of individuals in their life cycles. These organisms were once thought to form a monophyletic group in the Mycetozoa. After careful morphological, ultrastructural, and molecular studies, cellular slime molds are now thought to be distantly related organisms that have all converged on the cellular slime mold habit. The following thesis consists of two molecular phylogenetic studies on two named genera of cellular slime mold for which little or no molecular data were publically available. In the first study, gene sequence …

The Reproductive Ecology Of The Timber Rattlesnake, Crotalus Horridus, In Northwestern Arkansas: Interactions Between Environment, Steroid Hormones, And Life History, Craig Michael Lind

Graduate Theses and Dissertations

In this dissertation I examined the relationship between individual energetic status, hormone production, and life history trait expression in field-active Timber Rattlesnakes, Crotalus horridus. In chapter one I reviewed what is known regarding these relationships in snakes and defined major research goals. In chapter two I described the seasonal profile of testosterone (T) and corticosterone (CORT) in relation to the breeding season and to individual energetic status in males. Results showed that the seasonal pattern of T production in C. horridus was different than other pit viper species with similar mating patterns. Testosterone was elevated in the months leading up …