Biology Commons^™

A Cophylogenetic Analysis Of Fungus Gardening Ants And Their Symbiotic Fungi, Katherine Beigel

Biology Theses

Fungus-growing ants (Tribe Attini) and their fungal cultivars share a 50-million-year coevolutionary history. Large scale phylogenetic analyses depict a strong co-phyletic signal among ants and their farmed fungi yet fungus sharing among unrelated ant lineages is somewhat widespread. An overview of sharing has been hampered by a lack of genetic markers that exhibit intraspecific variation and surveys across geographic regions. For example, previous studies have shown similar sequences of the internal transcribed spacer (ITS) region of fungus in different species of Trachymyrmex, suggesting that these ant species are farming the same fungal clone. To examine whether this was a …

Modeling Neurofibromatosis Type Ii In Zebrafish, Hannah Nuszen

University Honors Program Senior Projects

Neurofibromatosis Type 2 (NF2) is a rare genetic disorder, classified as a neurocutaneous syndrome inherited through an autosomal dominant genetic mutation or deletion of the NF2 gene in humans. The tumor suppressor gene NF2 encodes the cytoskeletal protein MERLIN to promote apoptosis and inhibit abnormal cellular proliferation. Mutations in NF2 lead to a deficiency of functional MERLIN in humans and can result in hearing loss, disability, and premature death. These symptoms are due to uncontrollable growth of schwann cells generating bilateral benign tumors (schwannomas) within the nerve sheath of cranial nerve VIII. Here we seek to understand the function of …

Neogene And Quaternary Events Shaped Diversification And Speciation In Bhutanese Rheophilic Fishes Of The Family Nemacheilidae (Cypriniformes) And Sisoridae (Siluriformes), Karma Wangchuk

Graduate Theses and Dissertations

Biogeography of the Himalayan region [to include the Qinghai-Tibetan Plateau (QTP)] evolved over a ~30M year span, catalyzed by the collision of the Indian and Eurasian plates. The resulting uplift produced major ecological and climatic effects, that in turn drove the diversification of biodiversity. As a result, the QTP is designated as a global biodiversity hotspot particularly vulnerable to cumulative climatic effects, including shrinking distributions, declining numbers, and local extinctions. Understanding how the biodiversity within the Himalaya/ QTP was established and maintained is a necessary first step in prioritizing conservation efforts.

Fishes in global montane regions, such as the Himalaya, …

Assessment Of Genetic Diversity In Largetooth Sawfish, Pristis Pristis, Populations Over The 20th Century, Ann Fearing

Master's Theses

The Critically Endangered Largetooth Sawfish, Pristis pristis, experienced global declines in range and abundance over the past century and Australia is now their last stronghold. This research aimed to understand whether these declines have been accompanied by a reduction in levels of genetic diversity. Using P. pristis tissue samples sourced from natural history specimens, three fragments (616-bp, 386-bp, 141-bp) in the mitochondrial DNA (mtDNA) control region were PCR-amplified. At each fragment, significant genetic structure was found in P. pristis overall (Φ_ST=0.946, N=9; 0.813, N=54; 0.771, N=99). The Indo-West Pacific and Atlantic/Eastern Pacific each harbor genetically distinct lineages of …

Quantifying Structure And Variation In Complex Phylogenetic Data, Genevieve Geraldine Mount

LSU Doctoral Dissertations

Identifying the source and structure of variation in nature is crucial to understanding fundamental aspects of evolution. Despite a recent plethora of genetic and morphological data, many interesting questions about the relationships between different groups remain unresolved. My dissertation evaluates three approaches for identifying and quantifying the variation within phylogenetic datasets. Characterizing variation within datasets and across analytical methods gives insight into biologically interesting characters, unusual evolutionary processes, and areas for model improvement.

Network-based community detection approaches offer a powerful tool to describe variation in phylogenetic signal across the genome (i.e., gene tree variation). In Chapter 2, I investigate the …

Genetic Basis Of Hybrid Sterility Between Drosophila Pseudoobscura And D. Persimilis, Alannah J.P. Mattice

Electronic Thesis and Dissertation Repository

Speciation is the underlying process that leads to formation of new species, and therefore is the basis of biodiversity. Genes involved in each stage of speciation, such as those involved in interspecies sterility, remain elusive. Male hybrid sterility and postzygotic isolation between Drosophila pseudoobscura and D. persimilis was examined in this study through backcrossing of female hybrids into each parental line (introgression), selecting for a sterile sperm phenotype, needle-eye sperm. Sperm phenotypes did not separate through backcrossing; instead, males presented with multiple sperm phenotypes. A relationship between the phenotypes observed and the potential genes involved was examined through whole genome …

Identification And Characterization Of Novel Genes And Genetic Interactions That Influence Iba Metabolism, Vanessica Jawahir

Dissertations

Indole-3-butyric acid (IBA) is an endogenous storage auxin important for maintaining appropriate indole-3-acetic acid (IAA) levels that influences primary root elongation and lateral root development. IBA is metabolized into free IAA in the peroxisome in a multistep process similar to fatty acid β-oxidation. Although many components specific to IBA metabolism and peroxisome function have been identified, our understanding is incomplete. I sought to identify novel components of IBA metabolism or peroxisome function by conducting a forward genetic screen for Arabidopsis thaliana plants with enhanced resistance to IBA. I identified Long chain acyl-CoA synthetase 4 (LACS4) as a novel gene functioning …

Structure And Evolution Of Lizard Immunity Genes, Trent Santonastaso

University of New Orleans Theses and Dissertations

One of the most important gene families to play a role in adaptive immunity is the major histocompatibility complex (MHC). MHC class II loci are considered to be the most variable loci in the vertebrate genome, and studies have shown that this variability can be maintained through complex co-evolutionary dynamics between host and parasite. Despite the rich body of research into the MHC, there is comparatively little understanding of its genomic architecture in reptiles. Similarly, loci associated with innate immunity have received little attention in reptiles compared to other vertebrates. In the first chapter, we investigated the structure and organization …

Elucidating The Role Of Apl-1, The C. Elegans Ortholog Of The Human Amyloid Precursor Protein, Adanna G. Alexander

Dissertations, Theses, and Capstone Projects

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder, impacting approximately 6 million Americans. AD is the leading cause of dementia amongst the aged population. Post mortem analysis of the brains of AD patients shows high quantities of extracellular Aβ peptide deposits, which are derived from cleavage of the amyloid precursor protein (APP). Mutations in APP and proteins responsible for APP cleavage, PSENs, greatly increase the incidence of developing AD at an early age. Despite its strong correlation to the progression of AD, the role of APP remains unclear.

Here we investigate the role of the Caenorhabditis elegans ortholog, APL-1. We …

Elucidating The Role Of The High Aliphatic Glucosinolate ( Hag ) Genes In Pennycress ( Thlaspi Arvense L. ) Glucosinolate Production, Dalton Williams

Theses and Dissertations

Pennycress (Thlaspi arvense L.) is a Brassica species being developed into an oilseed-producing winter cash cover crop. Similar to its relatives, rapeseed (Brassica napus L.) and camelina (Camelina sativa L.), pennycress seeds produce high levels of oil and protein (~34% oil and ~19% protein dry weight). For pennycress to be economically viable and environmentally sustainable as a crop, both the oil and seed meal must be utilized. Pennycress like other Brassicaceae, produces high levels of glucosinolates in the seed coat. Glucosinolates taste bitter and can be metabolized by the enzyme, myrosinase, into toxic isothiocyanates, nitriles, and epithionitriles. Seed meal containing …

Determining The Genetic Control Of Neural Tube Malformation Through Genetic Interactions With Idgf3, Elli N. Fox

Honors Projects

Genetic mutations disrupting human neural tube formation can lead to birth defects such as spina bifida and anencephaly. Defects can result in lack of neural tube closure in either the caudal (spina bifida) or cranial (anencephaly) regions. Little is known about the genes that cause these malformations. Researchers have been using the model organism Drosophila melanogaster in an attempt to determine genes responsible for neural tube malformations. Recently, an ortholog of human chitin-like protein, imaginal disc growth factor 3 (Idgf3), has been identified as important in the proper formation of Drosophila egg dorsal appendages. However, the molecular mechanism responsible for …

Pathophysiology And Treatment Of Murine Globoid Cell Leukodystrophy, Yedda Li

Arts & Sciences Electronic Theses and Dissertations

Infantile globoid cell leukodystrophy (GLD, Krabbe disease) is a rapidly progressing, invariably fatal pediatric disorder first described in 1916. Krabbe disease is caused by a deficiency in the lysosomal enzyme, galactosylceramidase (GALC), and is characterized clinically by failure to thrive, limb stiffness, seizures, developmental regression, and death by 2-4 years of age. Galactosylceramidase degrades the cytotoxic glycolipid, galactosylsphingosine (psychosine). In the absence of GALC activity, psychosine accumulates primarily in oligodendrocytes and Schwann cells, resulting in profound demyelination. In 1972, psychosine was hypothesized to be responsible for the clinical signs associated with Krabbe disease. However, the ‘Psychosine Hypothesis’ has never been …

Investigation Of The Individual Soybean Root Nodule Microbiome, Parris Mica Mayhood

MSU Graduate Theses

Soybean is a valuable crop that establishes a symbiotic association with nitrogen-fixing microorganisms. Previous research suggests members of the genus Bradyrhizobium are the major nitrogen-fixing inhabitants of soybean root nodules. However, results from recent studies identified the presence of other bacteria, so called non-rhizobial endophytes (NREs), inside root nodules. All previous research has pooled nodules of different plants for bacterial community analysis, but this study investigated the presence and relative abundance of rhizobia and NREs within multiple root nodules of a single plant. Three sites were selected on Kendrick Farm in Springfield, MO, where three plants and rhizosphere soil were …

Understanding Cytochrome C Maturation In Anaerobic Archaea, Blake Wojciechowski

Biological Sciences Undergraduate Honors Theses

Methanoperedens nitroreducens (MPEBLZ), an archaeal methanotroph and close relative of Methanosarcina acetivorans, contain numerous cytochrome c proteins. However, difficulty in using these organisms as a model for cytochrome cresearch has created a pressure to express cytochrome c proteins in an organism that is much easier to work with. A punitive cytochrome c protein (MPEBLZ_04274) from M. nitroreducens was attempted to be cloned into a model methanogen M. acetivorans as well as Escherichia coli. Cytochrome c proteins are important for many metabolic processes within anaerobic archaea. In order for a mature cytochrome c to be formed heme must …

Evolutionary Ecology Of Host-Parasite Relationships: Role Of Host Ecology, Phylogeny, And Demographics In Shaping Parasite Evolution, Erika Taylor Gendron

Biology ETDs

Host-parasite systems exist across complex and ecologically heterogeneous landscapes, and may occur across taxonomically and ecologically disparate host species. Under these conditions, mechanisms underlying microevolutionary processes (i.e. gene flow, genetic drift) are not always clear, and may be mediated by numerous co-occurring factors specific to individual hosts. Host traits such as host immunology, demographics, phylogeny and ecology may act in concert to shape host-parasite relationships, and ultimately evolutionary processes. The research described herein used phylogeographic, phylogenomic, and population genetic methods to further understanding of how host traits impact the evolutionary ecology of trematode systems, using avian schistosomes (Digenea: Schistosomatidae) as …

Mushroom Body-Specific Gene Regulation By The Swi/Snf Chromatin Remodeling Complex, Kevin Cj Nixon

Electronic Thesis and Dissertation Repository

Over the lifetime of an organism, neurons must establish, remodel, and maintain precise connections in order to form neural circuits that are required for proper nervous system functioning. Disruptions in these processes can lead to neurodevelopmental disorders such as intellectual disability (ID) and autism spectrum disorder. Mutations in genes encoding subunits of the SWI/SNF chromatin remodeling complex have been implicated in ID, yet the role of this complex in neurons is poorly understood. In this project, I established cell-type specific methods to examine the effect of SWI/SNF subunit knockdowns on gene transcription and chromatin structure in the memory-forming neurons of …

A Mechanism For Sex Determination In Dioecious Cultivated Spinach, Nicholas West

Wayne State University Dissertations

While unisexual flowers have evolved repeatedly throughout angiosperm families, the actual identity of sex determining genes has been elusive, and their regulation within populations remains largely undefined. Additionally, sex liability is often observed in unisexual plants and has been correlated to external and internal cues, suggesting that the genes responsible for unisexual morphology are not necessarily segregating but rather differentially regulated. Understanding these processes will be of significant theoretical and agronomical importance.

Cultivated spinach is a dioecious species in which an individual will bear alternative sexual organs. Previous work has identified spinach B class floral organ identity genes, SpAP3 and …

Current Dog Breeding Practices Impacts On Health And Preservation Of Purebred Dogs, Bridget E. Baker

Honors Theses and Capstones

No abstract provided.

Analysis Of Genetic Structure And Pathogen Dynamics Of Ixodes Scapularis In Southwestern Virginia, Leemu Jackson

Undergraduate Honors Theses

Ixodes scapularis, or the blacklegged tick, is the primary vector of Borrelia burgdorferi. This pathogen is the causative agent of Lyme disease, the most common vector-transmitted disease in the United States. Although I. scapularis is distributed throughout the eastern U.S., Lyme disease is only considered endemic in the northeastern region of the country. Prior to 2007, Lyme disease was uncommon in Virginia, but since then cases of Lyme disease have increased dramatically with a hotspot forming in the Roanoke-Blacksburg area. The purpose of the current study was to determine whether B. burgdorferi prevalence and the genetic structure of I. …

The Exploration Of Nanotoxicological Copper And Interspecific Saccharomyces Hybrids, Matthew Joseph Winans Phd

Graduate Theses, Dissertations, and Problem Reports

Nanotechnology takes advantage of cellular biology’s natural nanoscale operations by interacting with biomolecules differently than soluble or bulk materials, often altering normal cellular processes such as metabolism or growth. To gain a better understanding of how copper nanoparticles hybridized on cellulose fibers called carboxymethyl cellulose (CMC) affected growth of Saccharomyces cerevisiae, the mechanisms of toxicity were explored. Multiple methodologies covering genetics, proteomics, metallomics, and metabolomics were used during this investigation. The work that lead to this dissertation discovered that these cellulosic copper nanoparticles had a unique toxicity compared to copper. Further investigation suggested a possible ionic or molecular mimicry …

Using Crispr-Cas9 As A Restriction Enzyme, Zack Crawley

Master's Theses

Restriction digests are a commonly utilized process for cleaving DNA at specific, but relatively common sites. Restriction enzymes have widespread use in DNA manipulation. CRISPR/Cas9 is a recently identified endonuclease which utilizes a customizable guide sequence to recognize and cut specific ~20 bp sites located in a DNA sequence. This preliminary research aimed to exploit the potential benefit of DNA restriction using the CRISPR/Cas9 procedure through alterations of different components involved in that system. We sought to refine existing CRISPR/Cas9 protocols and make a budget friendly, user-selectable CRISPR/Cas9 restriction digest protocol. The motivation for this research was to simplify and …

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 …

Spatial And Temporal Genetic Structure Of Winter-Run Steelhead (Oncorhynchus Mykiss) Returning To The Mad River, California, Steven R. Fong

Cal Poly Humboldt theses and projects

Distinct populations of steelhead in the wild are in decline. The propagation of steelhead in hatcheries has been used to boost population numbers for recreational fisheries and for use in conservation. However, hatchery breeding practices of steelhead can result in changes in genetic structure. I investigated the genetic structure of winter-run steelhead (Oncorhynchus mykiss) returning to the Mad River, California, where a hatchery has been used enhance production for recreational fisheries since 1971. Genetic variability in Mad River steelhead was evaluated using 96 single nucleotide polymorphisms (SNPs) among 4203 individuals, including the Mad River and nearby locations, and …