Master of Science, Miami University, 2022, Botany

Overabundant deer in the United States are a threat to forest regeneration and future forest composition due to browse on seedlings of preferred species. Controlled hunting programs are common for deer population management in parks. In this study, I investigated the Cincinnati Parks system's hunting program to determine if it was reducing deer density enough to facilitate tree regeneration. To do this, I completed surveys of seedlings, saplings, trees, palatable herbs, and invasive shrubs in five different sites within the Cincinnati Parks System. I found that in all sites, sapling densities were much lower than the 1,000 saplings/ha considered sufficient for forest regeneration. Four sites had seedling densities above 2,500 seedlings/ha considered sufficient for forest regeneration. However, when species that cannot contribute to future canopies (Fraxinus spp. and Asimina triloba) were excluded, all sites were below that density. Species preferred by deer were common in the canopy of the forests but were sparse in the seedling and sapling layer, suggesting that deer have shifted tree species composition over time. Deer densities have not decreased since 2007, suggesting that the hunting program is not decreasing populations sufficiently in the Cincinnati Parks. To facilitate tree regeneration, other management strategies should be considered.

Committee: David Gorchov (Advisor); Melany Fisk (Committee Member); Thomas Crist (Committee Member) Subjects: Botany; Ecology; Wildlife Management

Master of Science, The Ohio State University, 1923, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1967, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2006, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1971, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1971, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Environmental Science, Miami University, 2024, Environmental Sciences

This study compares two methods of estimating deer densities: distance sampling of deer fecal pellet piles and capture-recapture analysis [both spatially-explicit (SECR) and non-spatial (CR)]. These methods were used on two study sites in the Miami University Natural Areas (MUNAs) through the summer and fall of 2023. Previous estimates indicate MUNAs had high deer densities, which has led to seedling and sapling depletion (“regeneration failure”). In one MUNA, Bachelor/Reinhart, deer density estimates (deer/km2) were 7.5 from buck SECR, 40.5 from buck CR, 22.2 from fawn CR, and 4.4 from fecal pellet pile distance sampling. In another MUNA, Western/Beck, deer density estimates were 3.2 from buck SECR, 56.7 from buck CR, 42.5 from fawn CR, and 6.2 from fecal pellet distance sampling. I argue that buck SECR is the best estimate of deer density in the MUNA. I recommend buck SECR be used for future studies as it provides demographic and movement insights. Distance sampling provides similar estimates and is recommended for studies with limited time or funding. Results indicate a decline in deer densities, likely due to deer management begun in 2022; this should be continued to maintain deer populations at a density that mitigates regeneration failure.

Committee: David Gorchov (Advisor); Robbyn Abbitt (Committee Member); Thomas Crist (Committee Member) Subjects: Ecology; Wildlife Management

Master of Science (MS), Ohio University, 2024, Environmental Studies (Voinovich)

This study delves into the unique properties and applications of hydrochar, a distinct product of hydrothermal carbonization differing from conventional biochar and activated carbon. Hydrochar's potential as an efficient adsorbent is examined alongside the challenges posed by its utilization and production, particularly concerning residual alkalinity's influence on solution pH and the formation of insoluble metal hydroxides. The research primarily aims to optimize hydrochar's adsorptive capacity for removing Cu, Zn, and Cd from SMW by investigating the effects of processing parameters such as temperature, pH, and hydrochar dosage. Findings indicate that lower processing temperatures yield hydrochar with higher solubility and enhanced surface properties, with 260°C processing temperature demonstrating optimal metal removal, especially for Cu. However, the removal percentage for Zn and Cd remains relatively unaffected by processing temperature variations. Moreover, the study highlights the influence of pH on metal adsorption; the sorption of Zn and Cd were not significanty different, while Cu precipitated at pH 7. Subsequent analysis explores the impact of initial metal adsorption and subsequent desorption processes on hydrochar's structure and metal sorption in multiple treatment cycles, revealing structural degradation post-desorption and a continuous decrease in desorption efficiency across cycles. EDTA and HNO3 emerge as effective solvents for Cu and Zn desorption, respectively, despite inducing structural changes in the sorbent. These findings shed light on the complex interplay between hydrochar properties, processing parameters, and metal adsorption-desorption dynamics, crucial for optimizing hydrochar-based water treatment strategies.

Committee: Natalie Daniels Kruse (Advisor) Subjects: Environmental Studies

PhD, University of Cincinnati, 2024, Medicine: Molecular and Developmental Biology

The vertebrate heart is a multichambered structure requiring precise coordination of many signals and transcriptional regulators to properly develop. Disrupting this regulation can result in congenital heart defects (CHDs), which constitute the largest subset of congenital malformations. Many CHDs are subclinical until later in adult life, but it has been historically difficult to model severe heart defects in mature animals and because the molecular etiology of the majority of CHDs remains unknown. Nr2fs comprise a family of conserved orphan nuclear receptors with documented roles in cardiovascular development. Murine Nr2f2 is indispensable for specification and maintenance of atrial identity and human mutations in NR2F2 cause a variety of CHDs. However, elucidating the regulation imparted by Nr2f2 has been hindered by embryonic lethality in current mouse models. We bypassed this impediment utilizing a hypomorphic allele for a loss of nr2f1a (the zebrafish equivalent of mammalian Nr2f2), which survives to adulthood despite lacking an atrial chamber. We showed that an absence of the atrium causes morphological adaptations of the sinus venosus (SV) including increased cellularity and thickness of the elastic sinus walls. This remodeling was induced by increased hemodynamic stress and was rescuable upon treatment with vasodilators. RNA sequencing uncovered an unanticipated similarity between the SV and the bulbus arteriosus (BA) and showed that the mutant SV takes on an arterial-like identity. Additionally, comparing our SV and BA datasets to sequencing from the blood sinuses of the Ciona heart illuminated their shared evolutionary heritage. Since the focus of our developmental work spanned the entire lifetime of the fish, we also endeavored to explore cardiac regeneration. Although adult mammals cannot replace heart muscle lost in the event of myocardial infarction (MI), mature zebrafish can. However, investigations of myocardial regeneration in fish have f (open full item for complete abstract)

Committee: Joshua Waxman Ph.D. (Committee Chair); Tony De Falco Ph.D. (Committee Member); Stacey Huppert Ph.D. (Committee Member); Joshua Gross Ph.D. (Committee Member); Brian Gebelein Ph.D. (Committee Member) Subjects: Developmental Biology

Master of Science in Biomedical Engineering, Cleveland State University, 2023, Washkewicz College of Engineering

Tendons serve to attach muscles to bones, and are dense structures composed of fibers. Tendon injuries, as well as tendinopathies, in which a tendon is overused or has been degenerated due to sport injuries or age, are a large problem for many adult patients and account for about 30% of musculoskeletal diseases. Around 33 million musculoskeletal injuries have been reported per year in the United States alone, 50% of which involve tendon and ligament injuries. In American healthcare, only the flexor tendon lacerations sustain estimated costs of anywhere between $240.8 to $409.1 million per year. Having a slow metabolism, tendon tissue needs a substantial period to redevelop enough strength after injury. In most of the cases, tendon tissue does not have full functional recovery because of low regeneration capacity and scar tissue formation. Therefore, the healing of tendon injuries is a significant and clinically challenging problem requiring an urgent need to find alternative and cost-effective treatments. To address this problem, a combinatorial approach involving synergetic use of a 3- dimensional (3D) scaffold system with adult mesenchymal stem cells (MSCs) and locally applied electrical stimulation (ES) was used to produce bioactive extracellular vesicles (EVs) as novel therapeutic tools to enhance tendon regeneration. For this purpose, whey protein isolate (WPI)-based 3D scaffolds were developed to provide favorable microenvironment for MSCs attachment and growth. Conductive graphene and biodegradable Polylactic Acid (PLA) based flexible electronic coil was integrated to the 3D WPI scaffold to provide wireless ES of MSCs and modulate EVs secretion. The isolated EVs were characterized and applied to primary tenocyte cells to evaluate the regenerative activity. The results indicated that the isolated EVs, as well as applied ES, promoted the regeneration capacity of tenocyte cells in vitro and promoted the expression of tendon markers. This re (open full item for complete abstract)

Committee: Metin Uz (Committee Chair); Prabaha Sikder (Committee Member); Chandra Kothapalli (Committee Member) Subjects: Biomedical Engineering; Biomedical Research

Doctor of Organization Development & Change (D.O.D.C.), Bowling Green State University, 2023, Organization Development

This grounded theory research explores how individuals nominated by followers and peers as demonstrating exemplary leadership during adversity, specifically the COVID19 pandemic, experienced their leadership as a process. Of particular interest was understanding enabling and inhibiting factors and supports that would be helpful in future adversity contexts. The ability to adapt, grow and thrive in difficult circumstances has been discussed in prior literature including Post Traumatic Growth, Crucible Moments, and Growth Mindset. However, there is a paucity of research that looks at leaders specifically and what combinations of factors are enabling and inhibiting. Additionally, there is a lack of research regarding how leadership manifests as a process. A total of 17 interviews were conducted across industries ranging from hospitals to manufacturing to media to professional services. The narratives from these interviews were analyzed to develop a theoretical framework of exemplary leadership in adversity which shows the importance of three elements coming together to enable this experience in the form of an interdependent and regenerative system. These elements are Pre-adversity Preparedness, Disruptive Change Process and Post Adversity Growth, Learning and Adaption. An emergent model is presented as a Regenerative System of leadership defined by the concept of “Taking Care” of both business concerns and people concerns. The system existed as both restorative and regenerative in that it produced outcomes that exceeded conditions prior to the crisis and was described as transformative. Enabling subthemes of the system included previous experiences of the leader, pre-existing trusting relationships, adaptive human-centric and business-focused leader behaviors, leader-endorsed experimentation, defining moments of service, purpose, and change, leader supports, and personal and organizational growth, learning, and adaptation. These sub-themes demonstrated interdepend (open full item for complete abstract)

Committee: Deborah O Neil Ph.D (Committee Chair); Jacob Shila Ph.D (Other); David Jamieson Ph.D (Committee Member); Kristina LaVenia Ph.D (Committee Member) Subjects: Business Administration; Organization Theory; Organizational Behavior

Doctor of Philosophy, The Ohio State University, 2023, Molecular, Cellular and Developmental Biology

Cardiovascular disease is the leading cause of death worldwide, partly because humans lack appreciable capacity to repair or replenish lost or damaged cardiac tissue. Unlike mammals, adult zebrafish have a remarkable ability to regenerate large portions of cardiac tissues lost following injury. Most studies on zebrafish heart regeneration have focused on determining transcriptional changes occurring during this process. However, comparison of protein levels verses mRNA abundance shows that mRNA expression accounts for just 40% of the protein product. Only a minority of proteins, changing in abundance during heart regeneration, correlate with the amount of mRNA suggesting an important role for post-transcriptional regulation. Here, we describe a new family of translation factors called Eif4e1c which are related to canonical Eif4e proteins that initiate the rate limiting step of mRNA translation by binding to the 5' mRNA cap. Zebrafish mutants for eif4e1c have fewer cardiomyocytes and have reduced proliferation of heart muscle after injury. Additionally, eif4e1c mutants show widespread translational dysregulation of mRNA and metabolic changes in their hearts. Eif4e1c is more conserved throughout evolution than the canonical Eif4e proteins with a core group of 23 amino acids retained from ray-finned fish to sharks across ~480 million years. Interestingly, the Eif4e1c family is lost in amphibians and is absent from all terrestrial species. To our knowledge this makes eif4e1c the only fish specific gene with described roles in heart regeneration. In sum, we show that eif4e1c is critical for development and regeneration of zebrafish hearts revealing context-dependent requirements by translation initiation regulators during heart regeneration.

Committee: Joseph Goldman (Advisor); Amanda Bird (Committee Member); Jill Rafael-Fortney (Committee Member); Sharon Amacher (Committee Member) Subjects: Cellular Biology; Developmental Biology; Molecular Biology

PhD, University of Cincinnati, 2023, Medicine: Molecular and Developmental Biology

Respiratory pathologies are central causes of human morbidity and mortality. While few solutions have been developed to address acute lung injury, much less is known about how to prevent chronic disease/dysfunction or promote functional regeneration. Severe acute lung injuries (caused by influenza, bacterial pneumonia, COVID-19, etc.) lead to Acute Respiratory Distress Syndrome (ARDS), which biologically represents a combination of cell injury/death, barrier dysfunction, and airspace edema, resulting in a dysfunctional gas exchange and hypoxia. Patients with similar medical histories and presentations can have disparate outcomes following ARDS, and very little is known about determinants of this heterogeneity. Here, I will describe our efforts to explore this complex question, first looking at molecular mechanisms of progenitor populations of the alveolar epithelium using in vitro models and genetic knockouts, and second, using a perinatal non-human primate injury model to evaluate longitudinal regenerative impacts after early life injury. In Chapter 1, I discuss the history of alveolar epithelial regeneration driven by Alveolar Epithelial Progenitor (AEP) cells, framing the challenges facing the field at the outset of this work. In Chapters 2 and 3, I characterize our refined AEP-derived mouse clonal organoid model, wherein a single AEP expands into organoids that recapitulate in vivo epithelial cell type differentiation. Transcriptional regulatory network (TRN) analysis of time-series scRNAseq and scATACseq data from these organoids identified novel transcriptional regulators of each alveolar epithelial cell state. Using a newly optimized genetic perturbation model of progenitors using AAV6.2FF-Cre, we show novel cell-specific functions of the transcription factor Nkx2-1, a known master regulator in lung development. Loss of Nkx2-1 drives irreversible acquisition of a stressed cell state, a hypothesized initiator of many chronic lung diseases. Finally, we c (open full item for complete abstract)

Committee: William Zacharias M.D. Ph.D. (Committee Chair); Claire Chougnet Ph.D. (Committee Member); Leah Claire Kottyan Ph.D. (Committee Member); Aaron Zorn Ph.D. (Committee Member); Jeffrey Whitsett M.D. (Committee Member); Kathryn Wikenheiser-Brokamp M.D. Ph.D. (Committee Member); Emily Miraldi Ph.D. (Committee Member) Subjects: Developmental Biology

Master of Science, Miami University, 2023, Biology

Regeneration failure is a pressing issue in forests throughout eastern North America endangering the health of forests. White-tailed deer (Odocoileus virginianus) and invasive plants potentially contribute to failure by impacting tree seedling growth and survival. This study investigated the individual and interactive effects of deer and woody invasive plants on seedlings in an early successional forest. In a stand of Juniperus virginiana forest near Oxford, OH, we initiated a factorial experiment with each combination of deer access/exclosure and invasive woody plants removed/not removed. We planted native tree seedlings and monitored natural regeneration. Survival of planted Quercus rubra seedlings was lowest in invasive removal plots. Quercus rubra seedlings in deer exclosure plots grew taller, but there was no significant effect on height and survival of Liriodendron tulipifera seedlings. We found a marginally significant interaction of deer and invasives on natural regeneration survival: where deer were excluded, survival was higher where invasives were absent, but where deer had access, survival was much higher where invasives were present. Recruitment of native seedlings was greater in deer exclosure plots. Due to these findings, we recommend land managers in comparable early-successional forests focus on alleviating deer pressure over removing invasive plants.

Committee: David Gorchov (Advisor); Jonathan Bauer (Committee Member); Melany Fisk (Committee Member) Subjects: Biology

Master of Science (M.S.), University of Dayton, 2023, Biology

The critical role that the nervous system plays in driving amphibian limb regeneration underscores the impact that the brain may also have in this fascinating process. Earlier studies have suggested that unique protein synthesis occurs in the brain of regenerating newts upon limb amputation and have also exposed the prominent regenerative potential of brain-derived neural extracts from adult newts and chicken embryos. In the context of the current thesis, we employed a combination of in vivo axolotl limb amputation models, neurochemical and high-throughput proteomics approaches, as well as fluorescent immunohistochemistry to capture the temporal neuromolecular alterations that occur in the brain of regenerating axolotls. In our experimental setup, amputation and subsequent regeneration of the forelimbs affected the central proteomic signatures and neurochemistry in a time-dependent fashion into the regeneration program. To our knowledge this is the first study to systematically investigate the molecular and cellular dynamics underlying the activation of the limb-brain axis during amphibian limb regeneration, laying the groundwork for considering the role of the brain in the regulation of limb regeneration activity.

Committee: Pothitos Pitychoutis (Advisor); Mrigendra Rajput (Committee Member); Jennifer Hellmann (Committee Member); Katia Del Rio-Tsonis (Committee Member) Subjects: Biology; Neurosciences

Master of Science in Biological Sciences, Youngstown State University, 2023, Department of Biological Sciences and Chemistry

Forest canopy gaps are integral for regenerating most plants and maintaining regional diversity. However, native diversity in gaps is often compromised by exotic plant dominance and in the eastern United States, chronic overbrowsing by white-tailed deer (deer; Odocoileus virginianus). Notably, decades-long, near ubiquitous deer overabundance limits opportunity to study the dynamics of communities lacking persistent overbrowsing. Here, we ask how does spring and fall herbaceous and woody composition differ between areas with ≥50 years of low (~7 deer/km²) and high deer density (≥20 deer/km²). This was done in 2-14-year-old canopy gaps, ranging in size from 83-522m² (median: 230m²), in both mesic and drier temperate forest. Paired deer exclosure vs. control plots in two-year-old harvest gaps were also followed for three growing seasons to assess exclusion effects in low deer density areas only. Composition of browsable native and exotic plants (≤2m in height) did not differ between exclosure and control plots, indicating gap regeneration dynamics were unaffected by low deer density after three growing seasons. For spring flora, exotic relative cover increased with gap age, but native and exotic diversity did not differ across gap size, deer density, and habitats. However, for fall flora, exotic cover increased with gap age when deer were abundant, where communities averaged 380% higher non-native coverage. Fewer deer were associated with 75% higher native richness, 50% higher native diversity, and 60% more native cover across gap ages and habitats. Additionally, sapling height and stem density of red (Quercus rubra) and pin oak (Quercus palustris) were five- to twenty-fold higher with fewer deer. We find that managing white-tailed deer at roughly twice their historic abundance for 67-years facilitates all measured aspects of fall-flowering native understories, including early recruitment of four important canopy species, and reduces exotic plant abundance. (open full item for complete abstract)

Committee: Ian J. Renne PhD (Advisor); Thomas P. Diggins PhD (Committee Member); Walter P. Carson PhD (Committee Member) Subjects: Animals; Botany; Ecology; Forestry; Natural Resource Management; Wildlife Management

Doctor of Philosophy, Miami University, 2022, Cell, Molecular and Structural Biology (CMSB)

Lens regeneration in newts is a unique and astounding biological phenomenon that has fascinated scientists for centuries. During this process, the terminally differentiated iris pigmented epithelial cells (iPECs) of the dorsal iris, lose their differentiation status, and convert into an entirely new cell type to regenerate the missing lens. Interestingly, even though the iris epithelium is a homogenous tissue, only cells from the dorsal iris possess the capacity to regenerate a lens. The ventral iris pigmented epithelial cells never participate in this process. Therefore, this system presents a unique opportunity to compare regenerating competent and incompetent tissues at the cellular and molecular levels. This dissertation consists of four individual studies with a common goal of delineating the mechanisms that drive lens regeneration. In the first study (Chapter 2) we established and validated optical coherence tomography as a powerful tool to study lens regeneration. In the second study (Chapter 3), we evaluated the effects of aging on the lens regeneration process. We characterized in detailed the kinetics of lens regeneration in three different age groups. We found that young animals regenerated much faster than older ones and suggested that this phenomenon is due to delays in cell cycle re-entry and ECM remodeling. In the third study (Chapter 4), we investigated the role of macrophages during different stages of the newt lens regeneration process. We identified that macrophages play an important role to promote iPECs cell cycle re-entry, resolve inflammation, prevent fibrosis, and remodel extracellular matrix (ECM). Furthermore, we showed that exogenous addition of FGF2 or reintroduction of an injury can rescue regeneration in macrophage depleted eyes. This paper is finalized and will be submitted for publication soon. In the fourth and last study (Chapter 5), we explored the role of Ephrin:Eph pathway signaling during lens regeneration. Remarkably, we found (open full item for complete abstract)

Committee: Katia Del Rio-Tsonis Dr. (Advisor) Subjects: Biology

Doctor of Philosophy, Case Western Reserve University, 2023, Neurosciences

Neuroinflammation in the peripheral nervous system (PNS) is associated with the superior regenerative ability of the PNS compared to the CNS. A sciatic nerve lesion leads to the accumulation of macrophages at the lesion site, in the distal nerve (DN), and in the dorsal root ganglia (DRGs) containing the axotomized sensory neurons. These macrophages were thought to be primarily recruited from circulation by signaling through CCR2, the primary chemotactic receptor for circulating monocytes, using its ligand CCL2. Further, CCL2-CCR2 signaling was putatively required to induced a growth promoting macrophage phenotype. However, when we tested the role of CCL2 in vivo using both cell specific and global knockouts, we found no change in macrophage accumulation or regeneration. Two other CCR2 chemokines, CCL7 and CCL12, were upregulated by injury and compensated for the loss of CCL2 through CCR2 signaling. Using a Ccr2gfp knock-in/knock-out mouse we labeled recruited CCR2+ MDMs in a wildtype and CCR2 null background. Surprisingly, we found that DRG macrophage accumulation was normal in CCR2 null mice, and most were from a resident population. In both the lesion site and DN, most macrophages were MDMs, however resident macrophage proliferation and CCR2 independent recruitment mechanisms were activated to compensate for the loss of monocyte recruitment in CCR2 null mice. Importantly, despite being needed for monocyte recruitment, CCR2 signaling was not necessary for promoting axon growth. In CCR2 null mice, a peripheral conditioning lesion enhanced peripheral regeneration, maintained enhanced peripheral regeneration for 28 days, and enhanced regeneration in the dorsal root. Together demonstrating the CCL2-CCR2 signaling axis is not required for regeneration. We next devised experiments to test if macrophages in the DRG or nerve were stimulating regeneration. To test DRG macrophages, we lesioned two branches of the sciatic nerve which inflamed macrophages throughout the L3 an (open full item for complete abstract)

Committee: Jerry Silver (Committee Chair); Richard Zigmond (Advisor); Derek Abbott (Committee Member); Stanley Huang (Committee Member); Polyxeni Philippidou (Committee Member) Subjects: Immunology; Neurobiology; Neurosciences

PhD, University of Cincinnati, 2022, Medicine: Molecular and Developmental Biology

Heart failure causes millions of deaths annually and presents a large global healthcare burden. A regenerative cure for the damaged myocardium, where new muscle forms by proliferation of pre-existing cardiomyocytes, is an attractive therapeutic goal. Adult mammalian cardiomyocytes are terminally-differentiated, only capable of proliferating at a very low rate that is insufficient for a regenerative response after myocardial infarction. However, over the past decade, a transient innate capacity for cardiac regeneration during the early neonatal period has been described in both rodents and swine. Whether such a capacity exists in newborn human infants is unknown. Studying the mechanisms of regenerative potential in neonatal rodents and swine could offer greater insight into heart development in human neonates, and also facilitate discovery of novel targets for human heart disease therapy. Cardiomyocyte maturational processes occur concurrent with loss of heart regenerative potential in early neonatal mice. These maturational processes, and the transcriptional mechanisms regulating them, have been successfully manipulated to induce cardiac regenerative repair in adult mouse hearts after injury. Pigs also possess a similar period of early neonatal heart regenerative capacity as mice. However, the maturational dynamics of cardiomyocyte growth in the postnatal pig heart are not well-defined, despite popularity of swine as large mammal models for cardiac preclinical studies. In Chapter 2 of this dissertation, we describe cardiac maturation in postnatal swine from newborn to adolescent ages. Our results show discordance between time of terminal cardiomyocyte maturation and loss of heart regenerative potential in postnatal swine, dissimilar to rodents. Further, postnatal pig cardiomyocytes are distinct from rodents and humans, exhibiting extensive multinucleation of up to 16 nuclei per cardiomyocyte by 6 postnatal months. These differences hold importance for preclin (open full item for complete abstract)

Committee: Katherine Yutzey Ph.D. (Committee Member); Stacey Huppert Ph.D. (Committee Member); Joshua Waxman Ph.D. (Committee Member); Sakthivel Sadayappan Ph.D. (Committee Member); Nancy Ratner Ph.D. (Committee Member) Subjects: Developmental Biology

Doctor of Philosophy, University of Akron, 2022, Integrated Bioscience

Cadherins are cell-adhesion molecules that play important roles in animal development, maintenance and/or regeneration of adult animal tissues. In order to understand cadherins' functions in adult vertebrate visual structures, one must study their distribution in those structures. First, I examined expression of cadherin-6, cadherin-7, protocadherin-17 and protocadherin-19 in the visual structures of normal adult zebrafish using RNA in situ hybridization, followed by studying expression of two Kruppel-like transcription factors (klf6a and klf7), that are known markers for regenerating adult zebrafish retinas and optic nerves, in normal adult zebrafish brain, normal and regenerating adult zebrafish retinas. Then, I investigated expression of these cadherins in regenerating adult zebrafish retinas using both RNA in situ hybridization and quantitative PCR. Finally, as the first step in elucidating molecular mechanisms underlying protocadherin-17 (one of the cadherins that I studied) function in zebrafish visual system development, I used DNA microarray analysis to study gene expression of zebrafish embryos with their protocadherin-17 expression blocked by morpholino antisense oligonucleotides (these embryos are called protocadherin- 17 morphants). The major findings include: 1) cadherin-6, cadherin-7, protocadherin-17 and protocadherin-19 were differently expressed in the retina and major visual structures of normal adult zebrafish brain. 2) klf6a and klf7 showed similar expression patterns in most visual structures in the adult fish brain, and in regenerating retinas, but klf6a appeared to be a superior regeneration marker based on RNA in situ hybridization. 3) These four cadherin molecules showed distinct expression patterns in the regenerating zebrafish retinas. 4) Several genes involved in vision and/or visual development were significantly downregulated in the protocadherin-17 morphants compared to control embryos. My results suggest that (open full item for complete abstract)

Committee: Qin Liu (Advisor); Richard Londraville (Committee Member); Rolando Ramirez (Committee Member); Brian Bagatto (Committee Member); Zhong-Hui Duan (Committee Member) Subjects: Anatomy and Physiology; Bioinformatics; Biology; Developmental Biology; Molecular Biology