Biology
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Item Embargo Identification of a novel autonomous role for Ecdysone Receptor during Drosophila ovarian germ cell differentiation.(East Carolina University, July 2024) Jung, Lauren ElizabethA tightly regulated network of signals coordinates the division of Drosophila germline stem cells (GSCs) and differentiation of their daughter cells to produce viable oocytes. The steroid hormone, ecdysone, is known to promote GSC self-renewal; however, due to lack of compatible genetic tools, potential autonomous roles in the germline have not been fully evaluated. Ecdysone elicits a diverse array of transcriptional responses by binding to a heterodimeric complex composed of Ecdysone Receptor (EcR) and Ultraspiracle (Usp). To elucidate whether EcR facilitates autonomous reception of ecdysone in the germline, we built germline-compatible genetic tools to manipulate EcR levels or activity. Depleting EcR mRNA or loss of EcR ligand binding in the germline caused a loss of GSCs over time, demonstrating that it is necessary for GSC self-renewal. Further, over-expressing either EcR.A or EcR.B1 isoforms resulted in undifferentiated germ cell tumors and decreased numbers of GSCs. This is a ligand-dependent function of EcR, as over-expression of EcR that cannot bind ecdysone suppressed tumor development. By restricting over-expression to later stages of the germline, we found that EcR is sufficient to induce tumors only when over-expressed in the GSCs and early daughter cells. In tumorous ovaries, stem-like cells were also identified outside of their normal stem cell niche, suggesting that these cells remain competent to respond to BMP signals. Using single-cell RNA-sequencing to compare EcR over-expressing and Tkv over-expressing ovaries, we found remarkably similar transcriptomes in heterogenous populations of germ cells. These data suggest that EcR promotes differentiation of germ cells by directly regulating components of the BMP signaling pathway and that low levels of EcR expressed in wildtype GSCs are sufficient for ligand-dependent activation of an ecdysone-responsive transcriptional program. Altogether these data reveal a novel, autonomous role of EcR in GSC maintenance and regulation of differentiating daughter cells.Item Open Access Investigating the Role of the Antimicrobial Peptide TTO-53 in the Disruption of Pseudomonas aeruginosa Biofilm(East Carolina University, July 2024) Tilley, HannahPseudomonas aeruginosa infections are commonly acquired in hospital settings and are oftentimes severe and deadly. P. aeruginosa is known for its resistance to a wide range of antibiotics due to the low permeability of its outer membrane, possession of various efflux pumps and modifying enzymes, and its ability to form biofilms. Biofilms are aggregates of bacterial cells enclosed in an extracellular matrix. This extracellular matrix is composed of an assortment of extracellular polymeric substances (EPS’s) that can interact with and influence the rate of transport of antimicrobial agents. Previous research using a synthetic antimicrobial peptide made of unnatural amino acids named TTO-53 has shown its ability to disrupt pre-established P. aeruginosa biofilm. The goal of this study is to investigate how this disruption is taking place and the influence of this peptide on the efficacy of antibiotics in killing P. aeruginosa. Due to the role of quorum sensing, a communication system between cells in biofilm, in the maintenance of biofilms, we hypothesized that exposing P. aeruginosa to TTO-53 causes disruption of quorum sensing resulting in dispersion of pre-established biofilm. To test this hypothesis, we used quantitative real-time PCR (qRT-PCR) to determine if there was differential expression in genes within various quorum sensing pathways. Results from qRT-PCR showed that exposing overnight cultures to TTO-53 did not cause differential expression in genes within the LasR, PQS, and RhlI/RhlR quorum sensing pathways. To investigate the influence of TTO-53 on the efficacy of various antibiotics, we exposed cultures of PAO1 to varying concentrations of each antibiotic and compared the colony-forming units per milliliter (cfu/mL) of those cultures to the cfu/mL of cultures treated with those same concentrations of each antibiotic and TTO-53. These results indicated TTO-53 increases the efficacy of Chloramphenicol and Tazobactam/Piperacillin, while decreasing the efficacy of Tobramycin. This study revealed that an hour-long exposure to TTO-53 does not impact P. aeruginosa quorum sensing pathways and the combination treatment of TTO-53 has a synergistic effect with some antibiotics while inhibiting others.Item Open Access Hatch dates and habitat use of juvenile sheepshead Archosargus probatocephalus recruiting across a biogeographic divide in North Carolina.(East Carolina University, July 2024) Johnson, Maddie LeeThe goal of this study was to identify hatch dates of juvenile sheepshead (Archosargus probatocephalus) to confirm the spawning season for the species within North Carolina, and to identify potential spatial differences in early life history dynamics and habitat usage of juveniles. Spatial differences were compared across four locations to the North (Oregon Inlet) and South (Hatteras, Cedar Island, and Back Sound) of Cape Hatteras, a known biogeographical divide. Sheepshead are a coastal and estuarine species that are poorly understood in the region, especially concerning the juvenile stage. Sheepshead are managed by individual states and in North Carolina, a stock assessment is underway, and research on early life history dynamics was requested. The first objective of this study was to confirm the spawning season for sheepshead in North Carolina through a hatch date analysis. Transverse sections of sagittal otoliths were analyzed, and total age was used to identify hatch dates for juveniles in the four locations within North Carolina. The results determined that the general spawning season for sheepshead in North Carolina is April to May. Also, hatch dates varied spatially, especially between the Cape Hatteras breakpoint with fish from Oregon Inlet hatching later on average. The second objective was to determine fine-scale spatial differences in early life history dynamics across the Cape Hatteras breakpoint. Relationships between various important ages (total, pre-settlement, and post-settlement), timeframes (pelagic larval duration, juvenile stage), lengths (fork length and estimated size at settlement), and hatch dates were compared between locations. The results determined that early life history dynamics are variable across Cape Hatteras. Most notably, pelagic larval duration was longer for sheepshead collected north of Cape Hatteras. The final objective was to determine habitat utilization of juvenile sheepshead in Pamlico Sound. The utilization of various habitat types including seagrass beds, areas of oyster aquaculture, and unstructured sandy bottom habitats were compared. The results from this indicate that juvenile sheepshead have preferences for biogenic habitats, mainly areas of seagrass. The results from this study provide resource managers with more information on early life history dynamics of sheepshead in North Carolina. The confirmed spawning season can be further used as a baseline for additional research on reproductive biology of sheepshead. Additionally, this study provides methodology for any future research into a juvenile index of abundance, which can be used to create an index of annual recruitment. Finally, this study provides evidence of differences in early life history dynamics across Cape Hatteras and habitat preferences for the species.Item Embargo An exploration of the effects of productivity, predators, and nutrient enrichment on metacommunity structure(East Carolina University, July 2024) Leavitt, Jasper SiemannTo understand patterns in biodiversity, we first need to understand how it is organized across the landscape. Diversity can be measured in a single patch of habitat as the number of species and number of individuals per species, but patches do not exist in isolation. By organizing the landscape into a collection of patches of habitat, we can define the broader diversity of the metacommunity. By identifying changes to diversity in a single patch (local diversity or alpha diversity) and determining the heterogeneity of diversity among patches (turnover or beta diversity), we can begin to can predict changes in diversity across the landscape (regional diversity or gamma diversity). The aim of this dissertation was to investigate how abiotic and biotic factors influence beta diversity across multiple spatiotemporal scales using a variety of diversity metrics. Using a long-term dataset, I was able to determine that the relationship between primary productivity and species turnover varied across years in part due to annual fluctuations in environmental conditions. To answer questions about how changes to habitat suitability affected community assembly, I conducted experiments in artificial ponds to test the effects of predation and nitrogen enrichment on macroinvertebrates. Fish presence in ponds had a stronger effect on prey diversity than newt or Anax presence, reducing overall richness while increasing abundance of lower-trophic level taxa with some differences across spatial scales. Moderate nitrogen enrichment in ponds increased taxonomic heterogeneity and the heterogeneity of traits present among patches in the metacommunity, but overall, there were signs of functional redundancy across the metacommunity. Together, these results show the breadth of applications of metacommunity ecology for predicting the effects of multiple environmental factors on biodiversity across spatial and temporal scales.Item Restricted Soul FOOD: An Examination on the Physical Activity of Black Women(East Carolina University, 2023-12-15) Walker, JalenOverweight and obesity diseases lead to various critical health issues, including heart disease, high blood pressure, and type 2 diabetes. These diseases severely and disproportionately affect the Black female population as obesity rates are increasing at an alarming rate. Studies show that 80.6% of African-American women ages 20+ are overweight or obese and African American women have the highest rates of physical inactivity in comparison to other gender/ethnic groups. With African American women having the highest rates of overweight and obesity-related diseases and physical inactivity, it is a public health priority to develop and promote a program to develop and promote weight loss strategies for this underserved population. Intensive Lifestyle Interventions are used as a framework to combat obesity by providing increased physical activity recommendations, reduced caloric intake, and behavior therapy. These interventions have shown success in primarily White populations, but there has yet to be a feasible option provided specifically to the Black female community. Intervention guidelines such as physical activity recommendations and a reduced-calorie diet must be presented in a different manner than the traditional way. We have developed a program that not only provides an intervention that is feasible and attractive to the African-American female community but also creates a community amongst this population to continue to promote physical activity and healthier diet choices within the African-American female population. While ILIs incorporate behavioral counseling, they lack individualized tailored health coaching and the support for “how” to make the change. Focus group data collected in the Fall of 2021 provided data to develop a physical activity and nutrition program for Black women by Black women. This program was delivered virtually, due to COVID-19, to Black women to examine the impact of a tailored physical activity and nutrition program. Each week, Black women engaged in health behavior classes, social media groups, buddy programs, and either a physical activity or nutrition class. Women were provided with a Garmin physical activity tracker throughout the duration of the study and were asked to log their physical activity levels. We will examine physical activity data from the project to determine the impact the Soul FOOD intervention had on Black women’s physical activity levels.Item Restricted Comparison of degradable materials in escape panels on blue crab pots in North Carolina(East Carolina University) Winslow, Lancelot Delton.Item Restricted Differential expression of genes under conditions dissociating airway inflammation and hyperresponsiveness in a murine model of allergic asthma(East Carolina University) Wynne, Brandi M.Item Restricted Changes occuring [sic] on the cell surface during KSHV reactivation(East Carolina University) Whitman, Audy G.Item Open Access Wound repair and metal content of blue crabs, Callinectes sapidus, from the Albemarle-Pamlico Estuarine system(East Carolina University) Weinstein, John E.Item Restricted Genetics of alcoholism :pharmacological induction or suppression of alcohol drinking in low (LAD) and high (P) alcohol preferring rats(East Carolina University) West, Mark W.Item Restricted Protein kinase C delta and epsilon and time dependent change following ischemic preconditioning in a canine model of left ventricle hypertrophy(East Carolina University) Vice, Dirk J.Item Open Access Long-term (>10 yr) effects of thin-layer dredged material deposition on an irregularly flooded Juncus roemerianus-dominated brackish marsh(East Carolina University) Voss, Christine M.Item Restricted Fish passage through water control structures at Mattamuskeet National Wildlife Refuge, North Carolina(East Carolina University) Wall, Brian L.Item Restricted The effects of altered inudation and wrack deposition on nitrification, denitrification, and the standing stocks of NO and NO(East Carolina University) Taylor, James Harvey.Item Open Access Characterization of glycans on major histocompatibility complex class II molecules in channel catfish, Ictalurus punctatus(East Carolina University) Thankappan, Anil.Item Restricted Molecular evolution of the Hoxb5b gene in the moronidae(East Carolina University) Swan, Dennis D.Item Restricted Effects of dissolved oxygen concentrations on nitrification in coastal waters(East Carolina University) Tarnowski, Rebecca M.Item Open Access BCL-2's effect on gene regulation in MCF10A cells as detected by qRT-PCR(East Carolina University) Taylor, Andrew R.Item Open Access Histology of the female reproductive track in the crab, Panopeus Herbsti H. Milne Edwards (Brachyura:Xanthidae) :with relation to molt and reproductive cycles(East Carolina University) Stern, Mark Allen.Item Restricted Phylogeny and taxonomy of the Californian trapdoor spider genus Promyrmekiaphila Schenkel (Araneae, Cyrtaucheniidae)(East Carolina University) Stockman, Amy K.