Digital Commons Network^™

Dephosphorylation Of Mpk6 And Mpk3 By Phosphatases Modulates Responses To Herbivory In Arabidopsis, Claire Teresa Hann

Theses and Dissertations

As sessile organisms, plants rely on extracellular signals and chemical responses to defend against stressors. Extracellular stress signals inducing defense responses originate both from biotic or abiotic threats, and from products of tissue damage or hormones. In defense against herbivores, essential responses include rapid generation of jasmonic acid (JA) at the wound site, followed by the global expression of genes that impede digestion and growth. Early defense gene expression amplifies JA production, while later JA-responsive gene expression causes the accumulation of defense products. MAP kinase (MAPK) pathways play a central role in mediating the perception of self, non-self, and hormonal …

Modulation Of Eif2Α Signaling And The Integrated Stress Response By Targeted Therapeutic Attenuation Of Pkr Activity Contributes To Protection Of Dyt-Prkra Cells From Apoptosis, Kenneth L. Frederick

Theses and Dissertations

Luteolin is a natural flavonoid present in vegetables, fruits, and medicinal herbs that possesses anti-oxidative, anti-cancer, and anti-inflammatory properties. In this study, we investigated the effect of luteolin on the integrated stress response (ISR), which is an evolutionarily conserved intracellular signaling network essential for adapting to environmental stresses to maintain healthy cells. Dysregulated ISR is involved in the etiology of many human diseases including the movement disorder DYT-PRKRA which is caused by mutations in the PRKRA gene. PRKRA encodes for PACT, the protein activator of interferon-induced, double-stranded RNA (dsRNA)-activated protein kinase PKR.PACT-mediated PKR activation regulates the …

The Effects Of Variations In Light And Nutrient Availability On Phytoplankton And Zooplankton, Jake Anthony Swanson

Theses and Dissertations

Aquatic ecosystems experience a wide range of variation in resource availability; two of the resources that are most essential to phytoplankton and zooplankton are light and nutrients. Light can vary in both its color and intensity; these variations can directly impact phytoplankton by altering the amount and color of light available for photosynthesis. Nutrient variability, particularly increases in nutrient levels, also alter phytoplankton communities by favoring the growth of certain taxa such as cyanobacteria.

To understand whether phytoplankton respond differently to changes in light availability I investigated whether the diversification of cryptophytes, phytoplankton with diverse light-capturing pigments, showed evidence of …

Diversity, Function, And Phenotypic Plasticity Of Cryptophyte Phycobiliproteins, Kristiaän Merritt

Theses and Dissertations

Cryptophytes are a group of unicellular eukaryotic algae that can be found in a wide range of underwater habitats. Part of their ecological success can be attributed to their diverse array of cryptophyte phycobiliproteins (Cr-PBPs), a pigment class that captures wavelengths of light that are poorly absorbed by chlorophylls. Cryptophytes gained photosynthesis via secondary endosymbiosis in which their ancestor engulfed a red algal endosymbiont. Following endosymbiosis, they deconstructed the red algal photosynthetic machinery to form the Cr-PBP. Since then, the Cr-PBPs have diversified into at least 9 spectrally distinct forms. I investigated the diversity of Cr-PBP light absorption across 76 …

Genetic Mechanisms Underlying Maladaptation In Specialized Species Interactions, Nitin Ravikanthachari

Theses and Dissertations

Adaptation has been used as the framework to understand the power of natural selection in structuring biodiversity and driving biological interactions. However, recent examples have indicated that many organisms are maladapted to their local conditions. Maladaptation can result from various causes including rapid environmental change, novel environments, interplay of evolutionary forces (viz: gene flow-selection balance) and anthropogenic disturbance.

To dissect the genetic mechanisms underlying maladaptation, I used the interaction between Pieris macdunnoughii (Remington) (Lepidoptera: Pieridae) which lays eggs on an invasive mustard Thlaspi arvense (L.) (Brassicaceae), which is lethal to the larvae.

First, local adaptation to avoid laying eggs on …

Natural Variation Of Fructose-1,6-Bisphosphatase In Colias Butterflies, Andrea Blair Stokes

Theses and Dissertations

In a process known as the evolutionary recursion, it is possible to follow how adaptation affects natural selection at successive stages of a species’ life cycle. Through studying allele and genotype frequencies of enzymes in glycolysis, a central metabolic pathway, it is possible to document how polymorphisms can shift the evolving functionality of enzymes within or among species. Fructose-1,6-bisphosphatase (FBPase) is an enzyme in gluconeogenesis that converts fructose-1,6-bisphosphate to fructose 6- phosphate. It is also known to convert the unused amino acid carbon skeletons of glycolysis into glycogen storage. Appearing to play a vital role in the acquisition, storage, and …

Uncovering The Diverse Roles Of The Human Cst (Ctc1-Stn1-Ten1) Complex In Resolving Genomic Stress, Percy Logan Schuck

Theses and Dissertations

The CST (CTC1-STN1-TEN1) complex is a heterotrimeric single-stranded DNA binding protein known to stimulate polymerase α-primase (Pol α) and promote telomere length regulation, genome-wide DNA replication and double strand break repair. However, much of its cellular function remains unknown. The focus of my dissertation work was to uncover novel roles of CST in DNA stress response pathways. In particular, my work relates to understanding the function of CST in sister chromatid cohesion (SCC) and base excision repair (BER) as well as characterizing CST protein interactions. SCC is established following DNA replication by loading of the cohesion complex, which encircles replicated …

Molecular And Morphological Investigations Of Grouper (Serranidae) Biodiversity In Saudi Arabia, Mohammad Saeed Al Jazza Alqahtani

Theses and Dissertations

Chapter 1: The seas surrounding the Arabian Peninsula, which represent the northernmost portion of the Indian Ocean, are considered to have the highest aquatic biodiversity among the worlds marine regions. Seas that surround the Arabian Peninsula include the Red Sea, the Gulf of Aden, the Arabian Sea, the Gulf of Oman, and the Arabian Gulf. In aggregate, this area harbors a large number of endemic and more widespread marine species, including fishes, echinoderms, and corals.

There are unique challenges involved in grouper species identification in the Arabian region including ‘familiar’ Arabic species designations that are not standardized in the Arabic …

Methyltransferase Mystery: Epigenetic Mechanisms Induced By Food Limitation In Daphnia Pule, Trenton C. Agrelius

Theses and Dissertations

Daphnia are ecologically important organisms that have been well studied in the context of evolution, ecology, ecotoxicity, and genomics. Daphnia have strong maternal effects in which the environment experienced by the mother can alter offspring disease resistance, life history traits, and morphology, as well as gene expression and methylation for multiple generations. Coupled with their ability to reduce genetic differences via parthenogenesis, Daphnia are an ideal system for epigenetic studies involving the transmission of maternal effects. Using two clones of Daphnia pulex, we investigated the plasticity of life history and DNA methyltransferase (Dnmt) gene expression with respect to food …

In Vivo And In Vitro Investigations Of Mammalian Stem Cell Development: Neurogenesis And Pituitary Progenitors, Allison Culver

Theses and Dissertations

Human development is tightly regulated by complex mechanisms to pattern the early embryo and form specialized tissues. Understanding this regulation is of fundamental importance and can help further understand disease pathologies. Because it is difficult to observe the processes of interest, researchers must rely on the use of model systems. Our research goal is to combine both animal models and in vitro stem cell cultures to address key questions about the mechanisms of development for both the pituitary gland and brain. It is estimated that there are 290-455 cases per million of congenital hypopituitarism. In addition, autism spectrum disorder (ASD) …

Defining Molecular And Morphological Phenotypes In Ash1l-Deficient Human Neurons, Foster D. Ritchie

Theses and Dissertations

Autism Spectrum Disorders (ASD) are highly heritable neurodevelopmental disorders characterized by social and verbal impairments as well as repetitive behaviors. Large human genetic studies showed that genes encoding chromatin and transcriptional regulatory proteins are among the most commonly mutated genes in ASD. Absent, Small, or Homeotic 1-like (ASH1L) is a histone methyltransferase that has previously been identified as a major genetic risk factor for ASD. ASH1L di-methylates Histone H3 on Lysine 36 (H3K36me2) and tri-methylates Histone H3 on Lysine 4 (H3K4me3), which mainly coincides with transcriptional activation. ASH1L is a Trithorax protein that is proposed to counteract the activity of …

Cryptic Cryptophytes: The Plasticity In How Cryptophytes Respond To Changes In Resource Availability, Rachel Ann-Marie Schomaker

Theses and Dissertations

Resource variability and availability often drives competition within ecosystems, which can lead to the diversification of organismal niches and physiological capabilities. In aquatic systems, common resources that photosynthetic organisms, such as algae, compete for are light and carbon. Both the spectral characteristics (color) and carbon concentrations of an aquatic system vary with time and space, which means that algae need to be able to respond to changes in resource availability to survive. Using a group of ubiquitous unicellular eukaryotes known as cryptophytes, we investigated both how cryptophytes respond to changes in the available light spectrum at a physiological and genetic …

The Comparative Neuroethology Of Distributed Visual Systems: Visual Neuroanatomy And Visually-Mediated Behaviors Of The Chiton Acanthopleura Granulata And The Bay Scallop Argopecten Irradians, Daniel Ritter Chappell

Theses and Dissertations

Vision is usually thought to be inextricably linked to cephalization; however, certain species of invertebrates deviate from this canonical association by having noncephalized visual systems that are composed of numerous photoreceptive organs distributed across their body paired with centralized, decentralized, or distributed neural architectures. In contrast to cephalized visual systems, we know comparatively little about the visual processing and visually-mediated behaviors of animals with distributed visual systems which are crucial towards understanding how and why these animals see with so many eyes. In this dissertation, we investigate the visual neuroanatomy and visually-mediated behaviors of two different marine molluscs with distributed …

Functional Facets Of Intergenic Hairpin Structures In Genus Caulobacter, Geetha Saarunya Clarke

Theses and Dissertations

DNA replication, recombination and repairs maintain bacterial genome stability. But these processes may also induce genome rearrangements leading to inter andintra chromosomal structural variations. Genus Caulobacter undergoes extensive genome rearrangements. Genomic studies in bacteria usually focus on the codingregions, but there is important information present in the intergenic DNA spaces inaddition to the regulatory elements involved in transcription. Recently, Ely published a new model for recombination in genus Caulobacter with simultaneousloss and gain of genes resulting from preferential recombination at non- homologous regions flanked by regions of homology. In my dissertation, I observedand catalogued hairpin structures at known sites of …

From Gene Expression To Physiology: A Study Of Chronic Thermal Tolerance In The Mytilus Edulis Species Complex, Lindsey Cate Schwartz

Theses and Dissertations

Rising ocean temperatures are a severe and ever-present threat to marine life. With environmental temperature having such a large impact on organismal performance, understanding the mechanisms which contribute to the ability to survive at higher temperatures is a crucial research focus. Significant progress has been made in discovering these mechanisms on the cellular, biochemical, and physiological levels, but is it much less common for those to be examined together. Using the Mytilus edulisspecies complex as a model system, this dissertation takes a closer look at how prolonged exposure to sub-lethal high temperatures impacts marine organisms on multiple levels of …

The Effects Of Ionizing Radiation On Domestic Dogs: Ancestry And Genetic Structure Of Free-Roaming Dog Populations In Chernobyl, Ukraine, Gabriella Jean Spatola

Theses and Dissertations

This thesis is concerned with the effects of ionizing radiation on domestic dogs (Canis lupus familiaris) which were commonly used as laboratory subjects during the era of atomic bomb testing (1950s - 1980s). Early laboratory studies on radiation effects in dogs provided important foundations of knowledge for research that has more recently shifted to natural populations exposed to ionizing radiation from nuclear accidents. A unique group of free-roaming dogs reside in an environment polluted by radioactive contamination deposited during the Chernobyl nuclear disaster of 1986, providing one such opportunity to study the effects of ionizing radiation on dogs …

Understanding The Genomic Influence And Virulence Capabilities Of Environmentally Isolated Vibrios, Shannon Elizabeth Pipes

Theses and Dissertations

The genus Vibrio consists of Gram-negative bacteria that possess a curved rod shape and are routinely isolated from estuarine and coastal salt water. Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus are the major three species that contribute to human disease worldwide, and a variety of other Vibrio species contribute to persistent problems in the aquaculture and fishing industries. The CDC estimates that vibrios cause 80,000 cases of disease each year in the United States alone, however, this number is thought to be underestimated, since some disease is only self-limiting, meaning patients may not seek medical treatment and have …

Daphnia Pulex: The Mixed Messages Of Mutations , Matthew Randall Bruner

Theses and Dissertations

While mutations are almost universally considered to be more often deleterious than beneficial, their precise interactions between different populations and individual lines have been largely overlooked. Using mutation accumulation lines of four clones of obligately asexual Daphnia pulex, this research is intended to investigate the degree to which spontaneous mutation would affect fitness-related traits after roughly 100 generations. The expectation was that there would be a visible decrease in juvenile specific growth rate, the surrogate measurement used for fitness, across all four clones due to the deleterious nature of mutation in a selection free environment. Through measuring birth mass in …

Genetic And Epigenetic Regulations Of Eds1-Mediated Plant Immunity And Identification Of Bacterial Type Iii Effectors Targeting De Novo Dna Methyltransferase Drm2 In Arabidopsis, Ming Zhao

Theses and Dissertations

In Arabidopsis thaliana, Enhanced Disease Susceptibility1 (EDS1) acts as an indispensable hub in plant immunity and is mainly responsible for plant basal defense, systemic acquired resistance (SAR), increase of endogenous content of salicylic acid (SA) and effector-triggered immunity (ETI). Epigenetic regulators play crucial roles in multiple important cellular processes. As one catalytic core of Polycomb Repressive Complex (PRC2), CURLY LEAF (CLF/SDG1) protein promotes H3K27me3 deposition at specific loci for genes repression. In this work, I found that EDS1 interacted with epigenetic regulators SDG1, SDG9, SDG15, SDG22 and SDG35 in yeast two-hybrid assays. The growth of the bacterial pathogen Pseudomonas …

Trans-Axonal Signaling And Activity-Dependent Mechanisms Of Topographic Mapping And Refinement In Vivo, Olivia Marie Spead

Theses and Dissertations

Brain connectivity and function depend on the precise formation of neuronal connections during development. In the central nervous system, most axonal projections are organized into topographic maps according to the spatial organization of the neurons they originate from or the type of stimulus they respond to. Topographic mapping is in large part established by interactions between axons and their target as well as by activity-dependent pruning of mistargeted or excessive arbors. Another important mechanism contributing to topographic map formation is pre-target axon sorting, where axons become pre-ordered en route to their destination. Both topographic mapping and pre-target sorting involve the …

The Development Of A Tractable System To Assess Caulobacter-Plant Interactions, Louis Berrios

Theses and Dissertations

Bacteria play an integral role in regulating plant growth and development. However, many of the mechanisms encompassing bacteria-plant interactions are poorly understood and thus require detailed assessments (see CHAPTER 1). To this end, I coupled bacterial (Caulobacter sp.) and plant model organisms (Arabidopsis) to determine 1) the degree to which select bacteria can enhance the growth and development of plants, and 2) what functions these bacteria possess that enable them to aid plant development. Employing bacterial isolation techniques, monoculture inoculum-based plant growth assays, biochemical assays, comparative genomics, functional genetics, and real-time quantitative PCR (RT-qPCR), I determined that …

Characterizing The Temporal And Spatial Distribution Of The Cannonball Jellyfish (Stomolophus Meleagris) In The South Atlantic Bight, Lauren G. Faulk

Theses and Dissertations

The cannonball jellyfish, Stomolophus meleagris, is commercially harvested throughout its range in the tropical and sub-tropical Americas, including in the South Atlantic Bight, where an estimated 4,000 tons (less than 2.4% of the estimated stock in South Carolina during the spring) are harvested annually. Like many Scyphozoan jellyfish, cannonball jellies have high interannual variability and little is known about the environmental drivers of their distribution and phenology. To better understand the ecology of this targeted species, we used fisheries-independent abundance data of cannonball jellyfish from 2001 to 2019 collected by the Southeast Area Monitoring and Assessment Program (SEAMAP) throughout the …

Human Cst (Ctc1-Stn1-Ten1) Promotes Topbp1 Stability And Chk1 Phosphorylation In Response To Telomere Dysfunction And Global Replication Stress, Stephanie Michelle Ackerson

Theses and Dissertations

Genomic DNA is constantly damaged by both internal and external genotoxins and cellular processes. A consequence of unrepaired or misrepaired DNA damage is genome instability, a hallmark of cancer and numerous other diseases. Eukaryotic cells have developed complex mechanisms to repair DNA damage, which is collectively referred to as a DNA damage response (DDR). CST (CTC1-STN1-TEN1) is a heterotrimeric, RPA-like protein complex that binds to single stranded (ss)DNA. In humans, CST functions in the replication and maintenance of telomeres, structures found at the ends of linear chromosomes, as well as non-telomeric DNA. Previous studies showed that deletion of the largest …

Exploring Effects Of Sample Storage, Preparation, And Tissue Type On Fourier Transform-Near Infrared Spectroscopy (Ft-Nirs) Ageing Across Fish Taxa, Keith Fuller

Theses and Dissertations

The accurate determination of age for fish is a vital part of both populationmanagement and ichthyological research. However, the methods which are primarily employed to age fish can be difficult, time consuming, inaccurate, or some combination thereof. Most ageing is currently done via hard parts (such as otoliths, vertebrae, or scales) which are read in a manner similar to tree rings with markings corresponding to known or presumed periods of time. Recently, Fourier transform-near infrared spectroscopy (FT-NIRS) has been investigated as a novel tool to age fish more quickly and objectively. This method works by recording the vibrational frequencies of …

Applications And Mechanisms Of Near Infrared Spectroscopy For Age Estimation In Otoliths Of Red Snapper Lutjanus Campechanus, Michelle S. Passerotti

Theses and Dissertations

Near infrared spectroscopy (NIRS) is a light spectroscopy method useful for non-invasively discriminating and quantifying chemical composition of a wide variety of substances. Recently-developed applications of NIRS to fish age estimation across a range of taxa have sparked intense interest in exploring the feasibility of its use for rapid age estimation in fisheries population management. In this pursuit, development of species-specific calibration models relating traditionally-derived age estimates (i.e., those estimated from growth band counts) to NIR spectral signatures from ageing structures is required to derive predictive models that can then estimate age from rapid scans of whole ageing structures alone. …

Plasmids Bring Novel Functions To Caulobacter Genomes, Taylor Howell Carter

Theses and Dissertations

Caulobacter is a well-studied bacterial genus, but little is known about the plasmids that are found in some wild Caulobacter isolates. I identified nine plasmids from seven different Caulobacter strains and grouped them based on their size and the similarity of their repABC, parAB, and mobAB genes. Protein pathway analysis of the genes on the K31p1, and K31p2 plasmids showed many metabolic pathways that would enhance the metabolic versatility of the host strain. In contrast, the CB4 plasmid contained 21 heavy metal resistance genes organized into 9 operons. The majority of the CB4 heavy metal resistance genes code for …

Resrouce Allocation And Visual Communication In Lepidoptera, Linda Nicole Fipps

Theses and Dissertations

Visual signals in the form of wing color, size, shape, pattern, and UV reflectance play an important role in the mating and reproductive strategies of diurnal butterflies. Wing-based visual signals are linked to different functions and can be acted on by a variety of selective pressures. In a comprehensive look at the literature on the visual communication strategies of lepidopteran species, I look at how visual signals, most notably color, are used, generated, and perceived. I discuss the costs and benefits of those strategies for the fitness of butterflies and moths and look at lepidopteran visual communication through the lens …

Investigating The Dynamic Interactions Of Rapidly Growing Precocial Shorebird Chicks, Luke R. Wilde

Theses and Dissertations

Organisms in dynamic environments must continually reassess the cost-benefit trade-offs of their interactions and adjust their behaviors accordingly. Nevertheless, ecological research often takes a ‘snapshot’ approach to studying interactions across sample locations and timepoints. Investigating ecological interactions in this way can miss important information about the influence spatiotemporal context has on the scale and direction of their effects. Longitudinal studies that follow individuals can elucidate how changing contexts affect an individual’s ecology while deepening our understanding of adaptive behavior. However, determining how context influences the effect of an interaction requires it be measured across a range of spatiotemporal conditions. Studying …

Effect Of Oxidative Stress On Lifespan And Cellular Survival, Benedicth Onyeka Ukhueduan

Theses and Dissertations

When cells experience oxidative stress, the integrated stress response (ISR) signaling pathway is activated. One of the first outcomes of such ISR-activated response is to temporarily halt protein synthesis, which aids in cellular recovery. However, if cells cannot recover from the stress, they activate the cell death pathways which kills the affected cells, usually by apoptosis, which can then lead to either acquisition or prevention of diseases depending on the situation. In physiological aging, a compromised stress response is observed as an organism ages, which leads to disrupted homeostasis and elevated risk of disease. Thus, longevity of an organism is …

The Role Of Chromatin Remodeling Protein And Transcriptional Repressor, Ing4, In Hematopoiesis Regulation, Melanie Rodriguez

Theses and Dissertations

The hematopoietic compartment is tasked with the establishment and maintenance of the entire blood program. Key to this process are hematopoietic stem cells (HSCs), which possess the unique ability to self-renew and differentiate to replenish blood cells throughout an organism’s lifetime. In a screen for epigenetic regulators of hematopoiesis in zebrafish, we identified chromatin remodeling protein and transcription repressor, Ing4, as a requirement for hematopoietic stem and progenitor cell (HSPC) specification. Ing4, a member of the inhibitor of growth (ING) family, is a subunit of the HB01-JADE-hEAF6 histone acetyltransferase complex responsible for most nucleosomal histone H4 acetylation in eukaryotes. Ing4 …