Digital Commons Network^™

Genetic And Environmental Drivers Of Microbial Colonization In Wild Birds, Sage Rohrer

Dissertations

Wild birds are teeming with microorganisms, ranging from commensal bacteria to eukaryotic parasites. These microbes impact host health in diverse ways; some long-term residents may aid digestion or provide immune system training, while others at times may induce disease. However, the factors driving the varying colonization patterns seen across taxa are still not fully understood, and wild avian populations are particularly understudied when compared to mammalian or domesticated systems. This work examines the relative importance of genetic and environmental factors driving microbiome composition and function in wild birds. We collected fecal and blood samples from Galapagos penguins (Spheniscus mendiculus …

The Effects Of Floral And Social Information On Bumblebee Forager Learning And Memory, Avery Hume Baker

Theses

Bumblebees rely on information gathered from their environment to make the best choices they can when foraging for pollen and nectar. The type of information gathered should influence how a bee learns and remembers it, but other factors such as the size of the bee’s brain may also play a role in the learning and remembering process. While social information learned from other organisms and information gathered directly from flowers can each be used alone to improve both the efficiency with which a bee learns to forage from a flower and how accurately and how long the bee remembers these …

Taxonomic Revision And Morphometric Analysis Of Selected Anthurium (Araceae) Species From Bolivia And Peru, Daniel M. Tarazona Ocana

Theses

The genus Anthurium (Araceae) consists of around 1,200 species distributed in the Neotropics, particularly in Central and South America. The montane forests in the eastern flank of the Andes, ranging from northern Ecuador to central Bolivia; hereafter, the East Andes Gradient region, are particularly rich in terms of species diversity, and include an understudied group of Anthurium species endemic to the region. Within this group of species, some taxa are difficult to distinguish from each other mainly due to the lack of identification keys, incomplete species descriptions and unknown synonyms. In this study, a combination of traditional taxonomic techniques and …

Ferrocenium Salt Aided Substitution Reactions And Synthesis Of Glycosylated Curcumin Derivatives, Deva Saroja Talasila

Dissertations

Organic synthesis has been significantly advanced with the employment of transition metal complexes. The discovery of transition metal catalysts provided the synthetic community with powerful tools for accelerating reactions and making them more selective and efficient. Many chemical reactions do not happen without a catalyst.

Iron-based catalysts have several advantages for the chemical industry because it is a non-toxic and ecologically friendly metal. Our group previously found that ferrocenium cations with a 3+ oxidation state of iron-catalyzed propargylic substitution reactions at low temperatures. The sandwich structure of ferrocenes allows substituents to be introduced on the cyclopentadienyl rings, which allows for …

The Ecology And Evolution Of Species Rarity In Oaks (Quercus Spp.), Yingtong Wu

Dissertations

Rare species are susceptible to extinction due to ecological and genetic factors. Understanding the distribution, ecology, and evolution of rare species can provide useful information for effective conservation. To investigate species rarity, this dissertation focuses on a species-rich and ecologically diverse genus, Quercus (oaks). In Chapter 1, I aimed to understand how interactions between hosts and soil microbes contribute to habitat restriction in oak species. I performed a soil inoculum experiment on two pairs of sister oak species that show habitat divergence. I found that host-specific soil microbes contribute to habitat divergence and exclusion among sister species of oaks, but …

The Effects Of Prescribed Fire On Ant-Mediated Seed Dispersal In Missouri, Eva M. Colberg

Dissertations

Many aspects of animal-mediated seed dispersal are vulnerable to disturbance, including partner identity and dispersal quantity and quality. This dissertation explores ant-mediated seed dispersal of the herb Sanguinaria canadensis in Missouri Ozark oak forests, where prescribed fire is a common land management tool. In Chapter 1, I test the definition of a keystone seed disperser using absolute and relative contributions of different ant species to the quantity and distance of seed dispersal, based on field observations of S. canadensis seed dispersal. I demonstrate that the ant Aphaenogaster rudis is better described as a numerically dominant rather than keystone seed disperser, …

Immune Cell-Protein Interactions In Alzheimer’S Disease, Kapur Dhami

Dissertations

Misfolded protein aggregates are one of the significant contributing factors in many neurogenerative diseases including Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and others. My PhD research project was to study various aspects of amyloid-β peptide, a 40-42-residue peptide and the primary component of the senile plaques found in Alzheimer’s disease (AD) brains. One objective of my research was to purify and characterize the intermediate Aβ42 species using an array of biophysical techniques like size exclusion chromatography, fluorescence assays, circular dichroism, cellular assays, and protein assays. The other major research thrust of my project was to study the role of microglial …

Mechanism Of Sila- And Germafluorenes For Biological Applications, Shelby Jarrett

Dissertations

2,7-disubstituted silafluorenes and germafluorenes, originally designed for OLED applications, are a class of fluorescent dyes that have gained recent interest as probes for bioimaging and as biosensors to monitor cellular dynamics and interactions. Desirable biological probes absorb in the visible region, have high extinction coefficients, high quantum yield and excellent photostability. Here, their spectral properties are investigated under aqueous conditions for relevant biological applications. These molecules display intense blue fluorescence in the solid state and in solution, have high extinction coefficients, and exhibit appreciable solubility in aqueous solution. To better understand potential applications, the mechanism of fluorescence was investigated. It …

Effects Of Forest Restoration On The Recovery Of Dead Wood, Associated Arthropods, And Insect-Mediated Wood Decomposition, Estefania Fernandez Barrancos

Dissertations

Dead wood represents 8% of terrestrial carbon stocks and is an important source of habitat and food for decomposer and non-decomposer arthropods. However, anthropogenic disturbance reduces the amount of dead wood, putting at risk the presence of a habitat that is essential for many arthropods and other organisms that rely on it for food and shelter. Forest restoration aims to assist the recovery of ecosystems that have been damaged or destroyed and could be a means to recover both dead wood and its associated arthropod communities. This doctoral dissertation lies at the intersection of climate change, biodiversity loss and ecological …

Critical Corridor: Survey Of Predator Occurrence And Habitat Use In A Threatened Rainforest Protected Area: Comatsa-Sud And Marojejy National Park, Madagascar, Patrick H. Ross

Theses

Madagascar is a nation praised for its floral and faunal endemism and biodiversity. Among the island nation’s most emblematic fauna are its native mammalian carnivores; they are members of the threatened and endemic Eupleridae family. The Corridor of Marojejy – Anjanaharibe Sud – Tsaratanana (COMATSA) is a system of forest protected areas in which three large protected areas are connected in northern Madagascar: Tsaratanana Reserve, Anjanaharibe Sud Special Reserve and Marojejy National Park which is also a UNESCO World Heritage site. COMATSA is a newly protected and currently threatened corridor system that lacks detailed surveys and assessments of its native …

Liquid Biopsies For Type 2 Diabetes Mellitus: Biomarkers For Disease Risk And Diagnosis, Stephanie Chidester

Dissertations

Background: Type 2 diabetes mellitus (T2DM) has reached epidemic proportions in the United States. There is a critical need for earlier and more effective screening and diagnostic tools. Innovative liquid biopsy technologies may play a key role in meeting this need. Liquid biopsies are a non-invasive, adjunctive tool for determining diagnosis, prognosis, and therapeutic response. This dissertation focuses on two potential applications of liquid biopsy technologies to T2DM: (1) epigenome-wide association studies to identify epigenetic markers of risk for T2DM, and (2) extracellular vesicle (EV)-based biomarker studies to identify and detect markers associated with T2DM development and progression. Dissertation studies: …