Life Sciences Commons^™

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

Theses and Dissertations--Biology

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

Exploring The Molecular Basis Of Touch: A Comparative Analysis Of Gene Expression In Sensory Corpuscle-Rich And Corpuscle-Poor Skin Regions In The Duck, Thomas Hart

Theses and Dissertations--Biology

Cutaneous touch is facilitated by discrete cellular complexes composed of non-neuronal cells associated with mechanoreceptor neuron endings. The non-neuronal cells of these cutaneous end organ complexes (CEOCs) are believed to contribute to touch, but their role in touch sensation remains unclear. To better understand the function of CEOC cells, we sought to characterize the transcriptional profile of CEOC-rich tissue and identify genes expressed in CEOC cells. Bill skin of the tactile foraging Pekin duck (Anas platyrhynchos) is dense with CEOCs, specifically the avian analogs of mammalian Pacinian and Meissner corpuscles, while corpuscles in duck foot skin are scarce. Using RNA …

Parental Effects On Offspring Reaction Norms: Consequences For Complex Phenotypes In Variable Environments, Alexandra G. Cones

Theses and Dissertations--Biology

Organismal traits all exhibit some degree of environmental sensitivity, and both the strength and direction of these phenotypically plastic responses to the environment can evolve in adaptive ways. For example, parents can use information about their own environment to precondition the traits of their offspring so that they thrive in their future environment. This transgenerational plasticity can also alter the plasticity of offspring, but explicit investigations of this specific phenomenon are rare. I begin with a review of the literature and provide a quantitative genetic framework to investigate this phenomenon, which I then explore empirically using avian embryos. The metabolic …

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

Theses and Dissertations--Biology

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

Examining The Effects Of Hyperglycemia On Retinal Regeneration, Emmanuella Ec Kyllians

Theses and Dissertations--Biology

Diabetes is a disease that affects how the body processes glucose, leading to a cascade of other complications, one of which is diabetic retinopathy (DR). DR is a neurovascular disease that affects the retina and research has revealed the role of retinal neurodegeneration in its development. Animal models like zebrafish have emerged as important tools for studying the molecular and cellular mechanisms underlying DR. On the other hand, retinitis pigmentosa (RP) is a degenerative disease that involves the progressive degeneration of rods and cones, and hyperglycemia has been found to impair regeneration. Therefore, this study aims to examine the effects …

Competition And Herbivory Influence The Survival, Growth, And Physiology Of Native Tree Seedlings In The Kentucky Inner Bluegrass Savanna-Woodland, James D. Shaffer

Theses and Dissertations--Biology

Terrestrial plant communities are shaped by competition for resources, herbivory, and abiotic processes. Savanna systems represent a dynamic coexistence of contrasting life forms (grasses and trees) shaped by competition and disturbance. The Kentucky Inner Bluegrass Savanna-Woodland (KIBSW) is described as an open woodland of shade intolerant species; however, climatic, and edaphic conditions can support closed-canopy forest. After European pioneer settlement (c1750-1800), over 99% of “savanna-woodlands” have been lost. KIBSW remnants are experiencing a recruitment failure, leading to a dominance shift in tree communities. I researched how tree-grass competition and mammalian herbivory influence KIBSW regeneration and maintenance. The KIBSW does not …

Context-Dependency And Sex-Specificity Of Dispersal Syndromes, Allyssa Kilanowski

Theses and Dissertations--Biology

For populations in landscapes with increasingly heterogeneous and fragmented habitat patches (e.g., metapopulations), dispersal is an important behavior that leads to gene flow and connectivity among isolated patches. Because dispersal is a complex process, there are many traits involved. When suites of morphological, behavioral, physiological, and life-history traits covary with dispersal (e.g., a dispersal syndrome), the correlated traits can assist dispersing individuals through the complex process. Furthermore, once dispersal is completed, the correlated traits can influence the fitness of those dispersed individuals. Dispersal syndromes will likely interact with the local environment to produce ecological and evolutionary feedbacks on the metapopulation. …

Multilevel Phenotypic Integration Of Metabolism And Behavior In House Sparrows And Mice, Tim Salzman

Theses and Dissertations--Biology

Patterns of multilevel variation in behavior, both within and among individuals, raise challenging questions about underlying mechanisms and the selective pressures acting on them. One intriguing hypothesis is that physiology shows parallel multilevel variation, and so might represent a latent trait that integrates multilevel behavioral responses. For example, foraging acquires the fuel needed to maintain metabolism, and in turn, an individual’s metabolism affects expression of foraging, and other, behaviors. Metabolism and behavior thus might coevolve to become integrated traits. Despite the appeal of this hypothesis, numerous investigations into the link between metabolism and behavior have yielded largely equivocal results.

To …

Variation In Behavioral Strategies For Coping With Environmental Uncertainty, Allison Mclaughlin

Theses and Dissertations--Biology

My dissertation investigates how animals behaviorally respond to environmental change, especially when there is limited information about that change. Uncertainty about the environment comes in various forms, including food resources which vary unpredictably and novel cues which present an unknown level of potential risk or benefit. Various behavioral strategies help animals cope with such uncertainty. Tactics to manage unpredictable variation in food include gathering information to reduce uncertainty (sampling) and strategically adjusting preference or aversion to variation in resources (variance-sensitivity). To manage the uncertainty of a novel cue, animals may generalize their previous experience with similar cues, or they may …

Metabolic Diversity Among Fibroblasts From Regenerating And Non-Regenerating Mammals, Ebenezer Aryee

Theses and Dissertations--Biology

Regeneration is a wound repair process that terminates in the restoration of tissue function and structure. Fibroblasts play pivotal roles in regenerative and fibrotic wound repair. Reports of extensive regenerative ability in mammals have been historically rare, but more recently spiny mice (Acomys) have emerged as a bona fide model of complex tissue regeneration. Recent work has indicated that fibroblasts from regenerators (Acomys and Oryctolagus) are more resistant to reactive oxygen species (ROS)-induced senescence compared to non-regenerating species, suggesting the influence of intrinsic cellular states on the fate of wound repair. Determining the basal metabolic signature …

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

Theses and Dissertations--Biology

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

Assessing Ear Pinna Repair In The Mrl/Mpj Mouse Strain, Fatemeh Safaee

Theses and Dissertations--Biology

The outcome of tissue repair varies across species. Vertebrates such as salamanders have the ability to not only heal scar-free but also completely regenerate lost appendages. In contrast, most mammals heal their wounds with fibrotic scarring. Understanding the key drivers of these divergent injury responses remains a major unanswered question in animal biology. Previous work with the Murphy’s Roth Large (MRL/MpJ) inbred mouse strain suggested they have the ability to rapidly close small (2mm) ear holes. While this ability was originally published as an example of regeneration, subsequent work by other groups suggested that it might represent something more akin …

The Ecology And Evolution Of Human Reproductive Behavior, Kaylynne Glover

Theses and Dissertations--Biology

The complexity of human reproductive behavior has necessitated its examination through a variety of scientific disciplines, each focusing on specific elements of our biology, behavior, and society. However, this complexity also necessitates that we reintegrate the information learned from each discipline into a single framework, one rooted in the evolutionary principles that have shaped the development of all life on earth. In this dissertation, I use this framework to explore human reproductive behavior, with a particular focus on sexual coercion and fertility-mediated sexual behavior.

In Chapter 1, I introduce the approach taken in this document, identify several key limitations, and …

Estrogen Regulation Of Daily Metabolic Rhythms In Female Mice, Oluwabukola Omotola

Theses and Dissertations--Biology

Circadian rhythms are approximately 24-hour cycles of behavior, physiology, and gene expression. In mammals, these circadian rhythms are generated by clocks located in nearly every tissue in the body. The function of circadian clocks is to synchronize physiology and behavior with environmental cycles such as the light-dark cycle. After menopause, when circulating levels of estrogens are very low, women are more susceptible to obesity comorbidities such as metabolic syndrome and cardiovascular disease, suggesting that estrogens regulate these processes. Estrogens could protect females from metabolic dysfunction by regulating circadian rhythms. Consumption of diets that are high in fat contribute to obesity. …

The Role Of Sox4 In Ocular Morphogenesis And Retinal Differentiation, Rebecca Petersen

Theses and Dissertations--Biology

Visual impairment ranges from mild forms that can be corrected with glasses to more severe cases that result in permanent loss of vision. Microphthalmia, anophthalmia, and coloboma (collectively referred to as MAC) account for 11% of cases of pediatric blindness and are a result of improper ocular morphogenesis. Retinitis Pigmentosa (RP) is a retinal degenerative disease that affects 1 in 3000 people worldwide. It is a progressive disorder that initially begins with loss of vision in low light settings due to rod photoreceptor degeneration but progresses to complete blindness upon loss of cone photoreceptors. Currently, there is no cure for …

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

Theses and Dissertations--Biology

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

Understanding The Effects Of Embryonic Hyperglycemia On Retinal Development And Maintenance, Kayla Titialii-Torres

Theses and Dissertations--Biology

Hundreds of millions of people are affected by diabetes worldwide. Whether they are diagnosed with prediabetes or Type I or II diabetes, there are a variety of mechanisms in the pathogenesis of diabetes. Diabetes is a disease which consists of recurring states of hyperglycemia that can be difficult to manage due to either lack of insulin production or improper utilization of insulin. While these mechanisms of action differ, complications induced by diabetes occur in both poorly regulated Type I and II. Common complications of diabetes include nerve damage, kidney damage, and eye damage. Eye damage specifically is called diabetic retinopathy …

Spontaneous Postpartum Hypertension In The African Green Monkey, Patrick Rivera

Theses and Dissertations--Biology

Postpartum hypertension (PPHT) is a hypertensive disorder of the puerperium that occurs in women at a rate between 0.8-28% although the exact incidence is unknown due primarily to its transient presentation during a time of reduced medical supervision. The etiology of PPHT is currently unknown with no present experimental animal model. We present the African green monkey (Chlorocebus aethiops sabaeus; AGM) as a potentially translational NHP model of PPHT in humans. AGMs were identified as PPHT using Doppler sphygmomanometry and American Heart Association standards of hypertension for systolic blood pressure (systolic blood pressure > 140 mmHg). Disease characteristics were …

Impact Of Short Meditation On Attentional Performance, Lauren E. Guerriero

Theses and Dissertations--Biology

Meditation describes a large variety of traditions that all include the conscious focus of attention. By maintaining attention, meditators experience both acute and long-term changes in physiology, anatomy, and cognitive performance. The type of performance benefit is believed to depend, at least in part, on the specific type of mental training. What is much less clear in the literature is the impact of a single session of meditation on the brain and how the acute changes could impact performance. Studies in advanced meditators show an increase in neuronal coordination and slowing of neuronal firing across many regions in the brain, …

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

Theses and Dissertations--Biology

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

Cellular Bioenergetics Regulates Cell Proliferation During Mammalian Regeneration, Sandeep Saxena

Theses and Dissertations--Biology

Mammalian system consists of stress-sensing molecules that regulates their cellular response against damage, injury and oncogenic stress. During vertebrate regeneration, cells responding to injury re-enter the cell cycle and proliferate to form new tissue. Cell cycle re-entry or arrest is at least partly regulated by cellular senescence which negatively impacts the proliferative pool of cells during regeneration. What remains unclear is whether cells in regenerating systems possess an increased propensity to proliferate and are refractory to signals that induce senescence. My thesis work has focused on how fibroblasts from the ear pinna differentially regulate healing in highly regenerative mammals (e.g., …

Characterization Of Spontaneous Preeclampsia In The African Green Monkey (Chlorocebus Aethiops Sabaeus), Chelsea Christina Weaver

Theses and Dissertations--Biology

Hypertensive pregnancy disorders are a major contribution to maternal and neonatal mortality worldwide. Two of these disorders, preeclampsia and chronic hypertension in pregnancy, affect up to 10% of all pregnancies. These hypertensive disorders of pregnancy are associated with long-term, postnatal risk factors for both mother and offspring. Despite numerous recent advances in preeclampsia research, the underlying mechanisms are still not understood. This could be due to lack of a spontaneous animal model. This dissertation presents the African Green Monkey (AGM; Chlorocebus aethiops sabaeus) as the first known spontaneous animal model of preeclampsia and a highly translational model of chronic …

The Social Behavior Of Pine Sawflies In The Genus Neodiprion, John W. Terbot Ii

Theses and Dissertations--Biology

Group living is found across the animal kingdom ranging from temporary mating aggregations to complex, eusocial lifestyles. A particularly common form of group living found among insects are larval or nymphal herds. This lifestyle consists of immature insects living together and results in several proposed costs and benefits. Benefits of this lifestyle include improved ability to regulate a group’s microenvironment, more efficient use of their host, and the ability to engage in collective predator defenses. Offsetting these benefits are costs resulting from living in close proximity to conspecifics which include increased competition, greater visibility to predators, and heightened disease risks. …

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

Theses and Dissertations--Biology

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

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

Theses and Dissertations--Biology

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

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

Theses and Dissertations--Biology

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

Predicting Patterns Of Gene Family Evolution In Taxa With Similar Ecological Niches, Kim Vertacnik

Theses and Dissertations--Biology

To fully understand the genetic basis of adaptation, we need to know its predictability—the extent to which specific selective pressures and contexts can yield corresponding genetic changes. In particular, the repeated colonization of similar, specialized environments by different taxa is ideal for assessing the frequency of reoccurring changes in the same genes or functions. But compared to a growing body of literature on the convergent evolution of individual genes, far less is known about the repeatability of gene family evolution, where families (defined here as groups of genes that share sequence and functional similarity from common ancestry) can expand (gain …

Elucidating The Role Of Light-Induced Circadian Disruption On Atherosclerosis In Apolipoproteine-Deficient Mice, Jeffrey Chalfant

Theses and Dissertations--Biology

Circadian rhythms are approximately 24-hour oscillations of nearly every biological process in the body. The circadian system coordinates these rhythms of physiology and behavior with environmental cycles such as the light-dark cycle. Shift workers, who experience irregular exposure to the light-dark cycle, have chronically disrupted circadian rhythms and increased risk of developing cardiovascular disease, but the mechanisms are unknown. Our studies investigated the effects of light-induced circadian disruption on atherosclerosis in ApolipoproteinE-deficient (ApoE^-/-) mice. We found that male ApoE^-/- mice housed in constant light for 12 weeks, which results in severe disruption of circadian rhythms …

Investigation Into The Roles Of Her9 And Capn5 During Retinal Development And Regeneration, Cagney Coomer

Theses and Dissertations--Biology

The formation of a healthy and functioning eye requires coordinated interactions between numerous signaling pathways and gene regulatory networks within the developing neural retina. Tight regulation of gene expression is required for cell specification and differentiation in this multilayered, light sensitive tissue. The photoreceptors are the light detecting cells of the retina, capable of functioning in both intense sunlight and dim light at night. When pigment cells of the photoreceptor outer segment are activated by light, a complex chain of events called phototransduction leads to the electrical signal cascade that is transmitted through the retina and ultimately to the brain …

The Effect Of Ph On Synaptic Transmission At The Neuromuscular Junction In Drosophila Melanogaster, Catherine Elizabeth Stanley

Theses and Dissertations--Biology

Synaptic transmission is the main avenue of neuronal communication and can be affected by a multitude of factors, both intracellularly and extracellularly. The effects of pH changes on synaptic transmission have been studied for many years across many different models. Intracellular acidification at the presynaptic terminal is known to occur with increased neuronal activity and can also occur in pathological conditions. The effects of these pH alterations are therefore an important area of study. Here, intracellular acidification using either propionic acid or the ammonium chloride pre-pulse technique was examined for the effects on both spontaneous and evoked synaptic transmission at …