Life Sciences Commons^™

Assessing Endophyte Frequency Distributions And The Effect Of Epichloë Brachyelytri In The Chemotypic And Genotypic Diversity Of Brachyelytrum Erectum, Rachel Ann Sneed

Theses and Dissertations--Plant Pathology

Seed-transmissible epichloid fungal endophytes are best known for their roles as defensive mutualists in cool-season grasses. Historically, the discovery of fungal endophytes was driven by investigations of plant toxicity to livestock, followed by extensive study of their alkaloids and protection against insects and nematodes. Epichloae can produce four classes of alkaloids: ergot alkaloids, lolines (saturated aminopyrrolizidines), indole–diterpenes, and peramine. It is increasingly evident that these hereditary symbionts have much more diverse chemical profiles both in individual populations and between them. To this end, differences in chemotypic profiles of these symbionts may translate to different evolutionary and environmental advantages across plant …

Linking Previous Experiences To Behavior And Health In The Honey Bee (Apis Mellifera), Rebecca R. Westwick

Theses and Dissertations--Entomology

An organism’s ability to respond to changing conditions can be vital to its success. Indeed, plasticity is a common feature of living organisms. Much of the research in this area, though, has focused on effects caused by environmental conditions. What has received relatively less attention is how social experiences and broader features of an organism’s social environment can lead to long-lasting changes in health and behavior. This knowledge gap exists despite the well-documented existence of health and behavioral effects after social interactions in certain taxa such as humans.

Social insects such as honey bees provide an excellent opportunity to better …

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 …

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 …

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 …

Understanding The Cellular And Physiological Mechanisms Of Fertilization And Early-Stage Seed Development, Mohammad Foteh Ali

Theses and Dissertations--Plant and Soil Sciences

Flowering plants have evolved a unique double-fertilization process. Two sperm cells fuse with two female gametophytic cells, the egg and central cells within the ovule, giving rise to the embryo and endosperm, respectively. Sperm cells in flowering plants are nonmotile and delivered in close proximity to the egg and central cells by the pollen tube. Flowering plants have established filamentous actin (F-actin) based sperm nuclear migration system for successful fertilization. Prior to fertilization, the female gamete forms a mesh-like structure of F-actin that shows constant inward movement from the plasma membrane periphery to the center of the cell where the …

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. …

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, …

Residual Spatial Autocorrelation In Macroecological And Biogeographical Modeling: A Review, Guetchine Gaspard

Theses and Dissertations--Geography

Macroecological and biogeographical modelers have predicted the distribution of species across space relying on the relationship between biotic processes and environmental variables. Such a method employs data associated, for instance, with species abundance or presence/absence, climate, geomorphology, and soils. Statistical analyses found in previous studies have highlighted the importance of accounting for the effects of spatial autocorrelation (SAC), which indicates a level of dependence between pairs of nearby observations. A consensus has existed that residual spatial autocorrelation (rSAC) can substantially impact modeling processes and inferences. However, more emphasis should be put on identifying the sources of rSAC and the degree …

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 …

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 …

Mechanisms Of Cadmium-Induced And Epidermal Growth Factor Receptor Mutation-Driven Lung Tumorigenesis, Hsuan-Pei Lin

Theses and Dissertations--Toxicology and Cancer Biology

Cadmium (Cd) is a ubiquitous pollutant in the environment and a known carcinogen for lung cancer. Cd has been shown to act as a weak mutagen, which suggests that it may exert tumorigenic effect through non-genotoxic ways, such as epigenetic mechanisms. The goal of this project is to investigate the mechanisms of Cd carcinogenesis focusing on the role of lncRNA dysregulations. The Cd-exposed cells formed significantly more colonies in soft agar, displayed cancer stem cell (CSC)-like property and formed tumors in nude mice. Mechanistically, the lncRNA microarray analysis revealed that chronic Cd exposure dysregulates lncRNA expressions. Q-PCR analysis confirmed the …

Incorporation Of Summer Annual Mixtures Into Grazing Systems In Kentucky, Kelly Marie Mercier

Theses and Dissertations--Plant and Soil Sciences

Utilizing summer annual grass-legume forage mixtures has the potential to improve forage yield and nutritive characteristics, and/or animal performance during times when cool-season pasture growth is limited by high temperatures. Legumes can utilize atmospheric nitrogen, which can increase crude protein and forage digestibility in mixtures. As nitrogen application generally improves both the yield and nutritive characteristics of summer annual forages, but can have a negative effect on legume competitiveness, nitrogen fertilizer recommendations for legume-containing summer annual mixtures are not well established.

Two experiments were conducted to determine the feasibility of utilizing summer annual mixtures in Kentucky, USA. The first experiment …

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 …

From Genes To Species: Ecological Speciation With Gene Flow In Neodiprion Pinetum And N. Lecontei, Emily E. Bendall

Theses and Dissertations--Biology

My dissertation focuses on how differences accumulate across the genome during ecological speciation with geneflow. To do this I used two species of Neodiprionpine sawflies, which are plant-feeding hymenopterans with high host specificity. I used experimental crosses to measure both intrinsic and extrinsic postzygotic isolation and to understand the contribution of specific traits to reproductive isolation. Despite substantial genetic divergence and haploid males in which all recessive incompatibilities should be expressed, I found surprisingly little evidence of intrinsic postzygotic isolation. Recombination in hybrid males may reconstitute viable genotypes and counteract the effects of haploidy in males. Nevertheless, hybrids have …

From Organisms To Ecosystems: Impacts Of Limb Loss And Regeneration On Crayfish Behavior, Luc Arnaud Dunoyer

Theses and Dissertations--Biology

The ability of some organisms to regenerate tissues and organs has fascinated naturalists since antiquity, dating back to the earliest accounts of scientific inquiry with Aristotle in Ancient Greece. Then, Darwin’s theory invigorated some scientists’ dream of stimulating (or reactivating) regenerative capacities in human beings by showing that we are related to highly regenerative organisms. More recently, a renewed interest in discovering the molecular and genetic basis for organ and tissue regeneration has led biologists to focus more specifically on a restrictive set of model organisms.

Although the process of limb regeneration is different between invertebrate and vertebrate organisms, it …

The Role Of Melatonin In Biological Rhythms Of Songbirds, Clifford E. Harpole

Theses and Dissertations--Biology

In vertebrates, melatonin is a hormone that is produced and secreted at night and inhibited by light. This unique “darkness-only” expression profile makes it an intellectually appealing candidate for a means of transmitting temporal information to an individual, both time of day and time of year.

In passerine birds, “time of day” information is certainly transmitted via melatonin secretion. The primary producer of systemic melatonin in this family of birds is the pineal gland, and surgical removal of it causes a bird to become arrhythmic in constant conditions. I find that as pinealectomized house sparrows (Passer domesticus) become …

Effects Of Shelterwood And Patch Cut Harvests On A Post White-Nose Syndrome Bat Community In The Cumberland Plateau In Eastern Kentucky, Phillip Lee Arant

Theses and Dissertations--Forestry and Natural Resources

The impact of shelterwood and patch cuts harvests on bat communities was tested at three sites in Eastern Kentucky. Shelterwood harvests had 50% of the basal area and understory removed to create a uniform spacing of residual trees. Patch cuts had 1-hectare circular openings created to remove 50% of the basal area creating an aggregated spacing of residual trees. Acoustic detectors were deployed to assess activity levels pre-harvest. Sites were then sampled from 1 – 2 years post-harvest to determine differences. Pre-harvest data revealed little acoustic activity for the Myotis spp. at two sites. The remaining site had high activity …

Combination Of Investigational Cell-Based Therapy And Deep Brain Stimulation To Alter The Progression Of Parkinson’S Disease, Nader El Seblani

Theses and Dissertations--Pharmacy

Parkinson’s disease (PD) is the second most common neurodegenerative disorder and the motor symptoms are caused by progressive loss of midbrain dopamine neurons. There is no current treatment that can slow or reverse PD. Our current “DBS-Plus” clinical trial (NCT02369003) features the implantation in vivo of autologous Schwann cells (SCs) derived from a patient’s sural nerve into the substantia nigra pars compacta (SNpc) in combination with Deep Brain Stimulation (DBS) therapy for treating patients with advanced PD.

The central hypothesis of our research is that transdifferentiated SCs within conditioned nerve tissue will deliver pro-regenerative factors to enhance the survival of …