Developmental Biology Commons^™

The Integration Of Multiple Sources Of Sonic Hedgehog In The Spinal Cord Contribute To The Production Of First-Born Oligodendrocyte Precursor Cells Which Become Critical For Synapse Remodeling In Response To Adult Motor Neuron Injury, Lev Starikov

Dissertations, Theses, and Capstone Projects

Oligodendrocyte precursor cells (OPCs) arise sequentially first from a ventral and then from a dorsal precursor domain during spinal cord development. Whether the sequential production of OPCs is of physiological significance has not been examined. Here I show that interrupting Sonic hedgehog (Shh) signaling originating from nascent ventricular zone derivatives (VZD), motor neurons and the lateral floor plate, almost completely blocks ventral but not dorsal oligodendrogenesis without noticeably affecting early tissue patterning and embryonic development. In the absence of ventral OPCs, dorsal OPCs increase proliferation and populate the entire spinal cord with increased density. In these mutant mice, dOPCs take …

Molecular Analysis Of Cone Photoreceptor Genesis From A Specific Retinal Progenitor Population, Diego F. Buenaventura

Dissertations, Theses, and Capstone Projects

There are two types of photosensitive cells of the retina that contribute to image formation: Cone photoreceptors that mediate color discrimination and rods that provide photosensitivity in low-light conditions. Given the importance of cones in high acuity and color vision, deficiencies in this cell type that result from ailments such as retinitis pigmentosa and macular degeneration can lead to a debilitating loss of vision. Currently, one of the most pressing goals in the field of retinal development is the elucidation of the gene regulatory networks (GRN) involved in inducing an undifferentiated cell into becoming a functional cone photoreceptor.

Recently, an …

Nell2 Regulates The Contralateral-Versus-Ipsilateral Visual Projection As A Domain-Specific Positional Cue, Chizu Nakamoto, Elaine Durward, Masato Horie, Masaru Nakamoto

Biology Faculty Publications

In mammals with binocular vision, retinal ganglion cell (RGC) axons from each eye project to eye-specific domains in the contralateral and ipsilateral dorsal lateral geniculate nucleus (dLGN), underpinning disparity-based stereopsis. Although domain-specific axon guidance cues that discriminate contralateral and ipsilateral RGC axons have long been postulated as a key mechanism for development of the eye-specific retinogeniculate projection, the molecular nature of such cues has remained elusive. Here, we show that the extracellular glycoprotein Nell2 (neural epidermal growth factor-like-like 2) is expressed in the dorsomedial region of the dLGN, which ipsilateral RGC axons terminate in and contralateral axons avoid. In Nell2 …

A Developmental Study Of Apoptotic Markers And Histamine In Cephalopod Statocysts, Samantha Nicole Leef

Honors Theses and Capstones

Cephalopods can participate in complex navigation using landmarks that show context due to their statocysts. Statocysts are analogous to the vertebrate vestibular and auditory system encased in cartilage rather than bone making them more easily accessible. Age and anatomical dysfunctions are the reasons for many human vestibular malfunctions. Two of these sources are endolymph hydrops and aging. In the past, endolymph pressure changes were attributed to the ineffectual ion transport. Recent studies have illuminated the possibility of histamine receptors in the semicircular canal could be responsible for patients’ endolymph pressure changes rather than the previous belief that the pressure changes …

Modeling 3d Retinogenesis In Mouse Embryonic Stem Cells Following Crispr-Mediated Crx Knockdown, Pooja Prasad

Dissertations, Masters Theses, Capstones, and Culminating Projects

An emerging technology known as three-dimensional (3D) tissue engineering has allowed scientists to mimic tissues found in vivo. Previous studies indicate that it is possible to differentiate dissociated mouse embryonic stem cells (mESCs) into 3D retinal tissues in vitro (Bertacchi, 2015; Eiraku, 2012). The newly differentiated retinal tissues are said to encompass all of the major components found in retinal tissues. The generation of in vitro 3D tissues holds great potential in terms of patient-specific disease modeling. Although various diseases have been well-studied in animal models, there are limitations with regards to patient-specificity. The generation of animal models to study …

Transposon-Mediated Stable Suppression Of Gene Expression In The Developing Chick Retina, Masaru Nakamoto, Chizu Nakamoto

Biology Faculty Publications

The embryonic chick has long been a favorite model system for in vivo studies of vertebrate development. However, a major technical limitation of the chick embryo has been the lack of efficient loss-of-function approaches for analyses of gene functions. Here, we describe a methodology in which a transgene encoding artificial microRNA sequences is introduced into embryonic chick retinal cells by in ovo electroporation and integrated into the genome using the Tol2 transposon system. We show that this methodology can induce potent and stable suppression of gene expression. This technique therefore provides a rapid and robust loss-of-function approach for studies of …

Effects Of Chromium On Mouse Splenic T Lymphocytes And Effects Of Ethanol Exposure During Early Neurodevelopment On Behaviors In Mice, Lu Dai

Theses and Dissertations--Toxicology and Cancer Biology

The dissertation consists of three major projects with the focus on the immunotoxicity of chromium and the behavior disorders caused by early ETOH exposure respectively.

Hexavalent chromium [Cr(VI)] is widely used in various industrial processes and has been recognized as a carcinogen. As the first line of host defense system, the immune system can be a primary target of Cr(VI). T cell population represents a major arm of the immune system that plays a critical role in host anti-tumor immunity. Dysfunction of T cells compromises host anti-tumor immunity resulting in oncogenesis. Using mouse splenic T cells as an in vitro …

The Role Of Daf-19 In Non-Ciliated Neurons: How Is Neural Development Regulated By Different Daf-19 Isoforms?, Zabdiel Ek Vazquez

Lawrence University Honors Projects

A degenerative disease-like phenotype, specifically reduction in synaptic protein levels in adult worms, is correlated with loss-of-function of the only RFX transcription factor gene, daf-19, in C. elegans. This gene encodes four known transcription factor isoforms, two of which are correlated with particular functions. The DAF-19C isoform activates genes responsible for cilia development, while DAF-19M is needed for cilia specification in males. A comparison of the transcriptome of daf-19 null and isogenic wild type adult worms suggests both positive and negative regulation of gene expression is correlated with the presence of DAF-19 proteins. We have assessed DAF-19 regulation …

Roles Of Planar Cell Polarity Proteins In Copa Axon Pathfinding, Ashley Morgan Purdy

Theses and Dissertations

In zebrafish, CoPA (Commissural Primary Ascending) is the first among ascending commissural axons to pathfind anteriorly and form the spinal commissure. One pathway that guides their anterior growth is the planar cell polarity (PCP) signaling pathway, but it is not fully known how PCP signaling regulates anterior guidance. We examined CoPA pathfinding in various PCP mutants to determine if anterior-posterior (A-P) guidance of CoPAs is dependent on PCP signaling. We found that certain PCP mutants exhibited anterior pathfinding defects, with approximately half of all affected CoPAs migrating incorrectly posteriorly. By using a translation-blocking DCC (Deleted in …

Excess Folic Acid As A Potential Competitor Of Glutamate May Interfere With Neural Development, Benjamin Fick

Honors Program Theses

Folic acid, Vitamin B9, is strongly advised as a supplement taken by pregnant woman to maintain the health of the embryo, and deficiency increases the risk of neural tube defects. However, a safe upper limit of folate to consume has not been established, and an excess of dietary folate may interfere with neurodevelopmental metabolism, increasing the risk of adverse outcomes, including autism spectrum disorder (ASD). It has been suggested that folate affects connectivity among neurons as the brain develops. Glutamate is important in the regulation of neural tissue development, as it is a common excitatory neurotransmitter that binds to synaptic …

Potential For Aerobic Exercise To Release Growth Factors To Induce Cognitive Changes In Children With Autism Spectrum Disorder, Maya Harrington

Undergraduate Research Posters

Autism Spectrum Disorder (ASD) is becoming increasingly prevalent among adolescents, and while the number of individuals diagnosed with the disorder grows, there continues to be no cure or even a clear treatment path for ASD. This study analyzes the biological stimulations that create cognitive changes—which are induced by intensive aerobic exercise—within the brains of individuals ages 8-18 diagnosed with autism. I studied journal articles on the current treatments available for ASD, the increasing prevalence of the disease, the cognitive alterations of the autistic brain relative to the brains of individuals without the disease, the release of growth factors due to …

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 …

Pcdh19 Expression In Normal And Regenerating Adult Zebrafish Retinas, Kristin N. Forkapa Ms.

Williams Honors College, Honors Research Projects

My Honors Research Project will test the function of the N-cadherin molecule on the zebrafish optic nerve regeneration. N-cadherin is a member of the cadherin superfamily. Cadherins are cell adhesion molecules important for animal development and maintenance of adult structures. Unlike mammals, fish and amphibians have the ability to regenerate their optic nerve after damages. Molecular mechanisms underlying the optic nerve regeneration are still under intense investigation. Studies in Dr. Liu’s laboratory showed that expression of several cadherins, including N-cadherin, was greatly increased during adult zebrafish optic nerve regeneration, suggesting that cadherins may be involved in the optic nerve regeneration …

Role Of Sox11 During Vertebrate Ocular Morphogenesis And Retinal Neurogenesis, Lakshmi Shashidharan Pillai

Theses and Dissertations--Biology

Microphthalmia, anophthalmia, and coloboma (MAC) are distinct abnormalities demonstrating a continuum of developmental eye defects that contribute to 15-20% of blindness and severe vision deficiencies in children worldwide. The genetic etiology of MAC is large, complex and encompasses the whole developmental biology of the eye. Understanding how the eye develops will aid in identifying genes and developmental pathways involved in MAC. Although investigation of the genetic architecture of congenital anomalies is growing exponentially, much work remains to be accomplished to understand the complex, genetically heterogeneous congenital anomalies, which significantly impact childhood vision.

With an interest in elucidating the mechanisms that …

Dual Functions For Insulinoma-Associated 1 In Retinal Development, Marie A. Forbes-Osborne

Theses and Dissertations--Biology

Proper visual system function requires tightly controlled proliferation of a pool of relatively homogeneous retinal progenitor cells, followed by the stepwise specification and differentiation of multiple distinct cell types. These retinal cells, both neuronal and glial, must be generated in the correct numbers, and the correct laminar location to permit the formation of synaptic connections between individual cell types. After synapses are made, constant signaling is required as part of normal retinal function, and to maintain cellular identity and connectivity. These processes rely on both extrinsic and intrinsic signaling, with regulation of gene expression by cascades of transcription factors having …

Nel Positively Regulates The Genesis Of Retinal Ganglion Cells By Promoting Their Differentiation And Survival During Development, Chizu Nakamoto, Soh-Leh Kuan, Amy Findlay, Elaine Durward, Zhufeng Ouyang, Masaru Nakamoto, Ewa Zakrewska, Takuma Endo

Biology Faculty Publications

For correct functioning of the nervous system, the appropriate number and complement of neuronal cell types must be produced during development. However, the molecular mechanisms that regulate the production of individual classes of neurons are poorly understood. In this study, we investigate the function of the thrombospondin-1–like glycoprotein, Nel (neural epidermal growth factor [EGF]-like), in the generation of retinal ganglion cells (RGCs) in chicks. During eye development, Nel is strongly expressed in the presumptive retinal pigment epithelium and RGCs. Nel overexpression in the developing retina by in ovo electroporation increases the number of RGCs, whereas the number of displaced amacrine …

Developmental And Molecular Functions Of Plakophilin-3, William A. Munoz

Dissertations and Theses (Open Access)

Plakophilin-3, the less studied member of the plakophilin-catenin subfamily, and the larger catenin family, binds directly to desmosomal cadherin cytoplasmic domains and enhances desmosome formation and stability. In mammals, plakophilin-3 is expressed at the highest levels in desmosome-enriched tissues such as epithelia, with the knock-out in mice producing corresponding reductions in ectodermal integrity. In tissue, cellular and intracellular contexts where plakophilin-3 is not at the desmosomal plaque, little is known about its functions in the cytoplasm or nucleus, where it also localizes.

My work employed embryos of the amphibian, Xenopus laevis, to examine plakophilin-3’s developmental roles. I first evaluated …

Impairment Of Trkb-Psd-95 Signaling In Angelman Syndrome, Cong Cao, Mengia S. Rioult-Pedotti, Paolo Migani, Crystal J. Yu, Rakesh Tiwari, Keykavous Parang, Mark R. Spaller, Dennis J. Goebel, John Marshall

Pharmacy Faculty Articles and Research

Angelman syndrome (AS) is a neurodevelopment disorder characterized by severe cognitive impairment and a high rate of autism. AS is caused by disrupted neuronal expression of the maternally inherited Ube3A ubiquitin protein ligase, required for the proteasomal degradation of proteins implicated in synaptic plasticity, such as the activity-regulated cytoskeletal-associated protein (Arc/Arg3.1). Mice deficient in maternal Ube3A express elevated levels of Arc in response to synaptic activity, which coincides with severely impaired long-term potentiation (LTP) in the hippocampus and deficits in learning behaviors. In this study, we sought to test whether elevated levels of Arc interfere with brain-derived neurotrophic factor (BDNF) …

Structure-Function Analysis Of Nel, A Thrombospondin-1-Like Glycoprotein Involved In Neural Development And Functions, Masaru Nakamoto

Biology Faculty Publications

Nel (neural epidermal growth factor (EGF)-like molecule) is a multimeric, multimodular extracellular glycoprotein with heparin-binding activity and structural similarities to thrombospondin-1. Nel is predominantly expressed in the nervous system and has been implicated in neuronal proliferation and differentiation, retinal axon guidance, synaptic functions, and spatial learning. The Nel protein contains an N-terminal thrombospondin-1 (TSP-N) domain, five cysteine-rich domains, and six EGF-like domains. However, little is known about the functions of specific domains of the Nel protein. In this study, we have performed structure-function analysis of Nel, by using a series of expression constructs for different regions of the Nel protein. …

In Vitro Guidance Of Retinal Axons By A Tectal Lamina-Specific Glycoprotein Nel, Yulan Jiang, Hiroya Obama, Soh-Leh Kuan, Ritsuko Nakamura, Chizu Nakamoto, Zhufeng Ouyang, Masaru Nakamoto

Biology Faculty Publications

Nel is a glycoprotein containing five chordin-like and six epidermal growth factor-like domains and is strongly expressed in the nervous system. In this study, we have examined expression patterns and in vitro functions of Nel in the chicken retinotectal system. We have found that in the developing tectum, expression of Nel is localized in specific laminae that retinal axons normally do not enter, including the border between the retinorecipient and non-retinorecipient laminae. Nel-binding activity is detected on retinal axons both in vivo and in vitro, suggesting that retinal axons express a receptor for Nel. In vitro, Nel inhibits retinal axon …

Neuronal Pentraxins Mediate Synaptic Refinement In The Developing Visual System, Lisa Bjartmar, Andrew Huberman, Erik Ullian, Rene Renterıa, Xiaoqin Liu, Weifeng Xu, Jennifer Prezioso, Michael Susman, David Stellwagen, Caleb Stokes, Richard Cho, Paul Worley, Robert Malenka, Sherry Ball, Neal Peachey, David Copenhagen, Barbara Chapman, Masaru Nakamoto, Ben Barres, Mark Perin

Biology Faculty Publications

 Neuronal pentraxins (NPs) define a family of proteins that are homologous to C-reactive and acute-phase proteins in the immune system and have been hypothesized to be involved in activity-dependent synaptic plasticity. To investigate the role of NPs in vivo , we generated mice that lack one, two, or all three NPs. NP1/2 knock-out mice exhibited defects in the segregation of eye-specific retinal ganglion cell (RGC) projections to the dorsal lateral geniculate nucleus, a process that involves activity-dependent synapse formation and elimination. Retinas from mice lacking NP1 and NP2 had cholinergically driven waves of activity that occurred at a frequency similar …

Sexually Dimorphic Effects Of Prenatal Stress On Cognition, Hormonal Responses, And Central Neurotransmitters, Rachel E. Bowman, Neil J. Maclusky, Yessenia Sarmiento, Maya Frankfurt, Marisa Gordon, Victoria N. Luine

Psychology Faculty Publications

Exposure to stress during gestation results in physiological and behavioral alterations that persist into adulthood. This study examined the effects of prenatal stress on the postnatal expression of sexually differentiated cognitive, hormonal, and neurochemical profiles in male and female rats. Pregnant dams were subjected to restraint stress three times daily for 45 min during d 14-21 of pregnancy. The offspring of control and prenatally stressed dams were tested for anxiety-related and cognitive behaviors, stress and gonadal steroid hormone levels, as well as monoamines and metabolite levels in selected brain regions. Postnatal testosterone levels (measured at 1 and 5 d) did …

Loss-Of-Function Analysis Of Epha Receptors In Retinotectal Mapping, David Feldheim, Masaru Nakamoto, Miriam Osterfield, Nicholas Gale, Thomas Dechiara, Rajat Rohatgi, George Yancopoulos, John Flanagan

Biology Faculty Publications

EphA tyrosine kinases are thought to act as topographically specific receptors in the well-characterized projection map from the retina to the tectum. Here, we describe a loss-of-function analysis of EphA receptors in retinotectal mapping. Expressing patches of a cytoplasmically truncated EphA3 receptor in chick retina caused temporal axons to have reduced responsiveness to posterior tectal repellent activity in vitro  and to shift more posteriorly within the map in vivo . A gene disruption of mouse EphA5, replacing the intracellular domain with beta-galactosidase, reduced in vitro  responsiveness of temporal axons to posterior target membranes. It also caused map abnormalities in vivo …

Eph Receptors And Ephrins, Masaru Nakamoto

Biology Faculty Publications

The Eph receptors are the largest known family of receptor tyrosine kinases. The Eph receptors and theirmembrane-attached ligands, ephrins, show diverse expression patterns during development. Recent studies havedemonstrated that Eph receptors and ephrins play important roles in many developmental processes, includingneuronal network formation, the patterning of the neural tube and the paraxial mesoderm, the guidance of cellmigration, and vascular formation. In the nervous system, Eph receptors and ephrins have been shown to act aspositional labels to establish topographic projections. They also play a key role in pathway ®nding by axons andneural crest cells. The crucial roles of Eph receptors and …

Topographically Specific Effects Of Elf-1 On Retinal Axon Guidance In Vitro And Retinal Axon Mapping In Vivo, Masaru Nakamoto

Biology Faculty Publications

Topographic maps, which maintain the spatial order of neurons in the order of their axonal connections, are found throughout the nervous system. In the visual retinotectal projection, ELF-1, a ligand in the tectum, and its receptors in the retina show complementary gradients in expression and binding, indicating they may be positional labels for map development. Here we show that ELF-1 acts as a repellent axon guidance factor in vitro. In vivo, when the tectal ELF-1 pattern is modified by retroviral overexpression, retinal axons avoid ectopic ELF-1 patches and map to abnormally anterior positions. All these effects were seen on axons …

Complementary Gradients In Expression And Binding Of Elf-1 And Mek4 In Development Of The Topographic Retinotectal Projection Map, Masaru Nakamoto

Biology Faculty Publications

Topographic maps with a defined spatial ordering of neuronal connections are a key feature of brain organization. Such maps are believed to develop in response to complementary position-specific labels in presynaptic and postsynaptic fields. However, the complementary labeling molecules are not known. In the well studied visual map of retinal axons projecting to the tectum, the labels are hypothesized to be in gradients, without needing large numbers of cell-specific molecules. We recently cloned ELF-1 as a ligand for Eph family receptors. Here, RNA hybridization shows matching expression gradients for ELF-1 in the tectum and its receptor Mek4 in the retina. …