Life Sciences Commons^™

Genetic Effects Of Anthropogenic Disturbance On Native Charrs, Brad Erdman

Electronic Theses and Dissertations

Artificial propagation has been utilized for over a century to offset anthropogenic declines of abundance for many fishes. Complex and poorly documented histories of habitat degradation and stockings have resulted in considerable uncertainty regarding whether contemporary populations are of native, hatchery, or mixed origins. This uncertainty is problematic as it precludes prioritizing the conservation of native populations that are postulated to possess local adaptations and greater evolutionary potential. Population genetics can assess the relative reproductive contributions of previous stocking events and in this dissertation I apply these methods to four empirical studies of native charr (genus Salvelinus) that have …

Genetic Determinants Of Primary Nociceptor Sensitivity In Drosophila Melanogaster, Christine Hale

Electronic Theses and Dissertations

Abnormal pain affects ~50 million adults nationwide. With many of the current treatment options for chronic pain, such as opioid analgesics, carrying side effects such as the threat for addiction, research into safer and more effective options for chronic pain relief is crucial. Abnormal alterations in nociceptive sensitivity, which is the sensitivity of peripheral sensory neurons that detect noxious stimuli, can underlie, and perpetuate chronic pain. However, much is still unknown about the mechanism of how these abnormal alterations in sensitivity occur. To help elucidate genetic components controlling nociceptive sensitivity, the Drosophila melanogaster larval nociception model has been used …

Retroviral Infection Dynamics In Maine's Wild Turkeys, Stephanie A. Shea

Electronic Theses and Dissertations

Widespread wild turkey reintroductions in the late 1900s have led to increases in population density and geographic distribution across North America. This rapid population expansion has put them into proximity with closely-related wild and domestic avian species, increasing the risks of pathogen transmission. Lymphoproliferative disease virus (LPDV) is an avian oncogenic retrovirus detected in wild turkeys in 2009, and previously known to infect domestic turkeys. Following its initial detection, surveys reported variable LPDV prevalence across eastern North America with most wild turkeys being asymptomatic, however diagnostic cases revealed 10% mortality of LPDV-infected individuals. Given its recent detection, little is known …

Deciphering The Perpetual Fight Between Virus And Host: Utilizing Bioinformatics To Elucidate The Host's Genetic Mechanisms That Influence Jc Polyomavirus Infection, Michael P. Wilczek

Electronic Theses and Dissertations

JC polyomavirus (JCPyV) is a human-specific pathogen that infects 50-80% of the population, and can cause a deadly, demyelinating disease, known as progressive multifocal leukoencephalopathy (PML). In most of the population, JCPyV persistently infects the kidneys but during immunosuppression, it can reactivate and spread to the central nervous system (CNS), causing PML. In the CNS, JCPyV targets two cell types, astrocytes, and oligodendrocytes. Due to the hallmark pathology of oligodendrocyte lysis observed in disease, oligodendrocytes were thought to be the main cell type involved during JCPyV infection. However, recent evidence suggests that astrocytes are targeted by the virus and act …

Translational Fidelity And Its Role In Neuronal Homeostasis, Markus Terrey

Electronic Theses and Dissertations

The process of translation, which refers to decoding genetic information from mRNA to protein, is vital for all cellular function. Translational fidelity starts at the level of aminoacylation of transfer RNAs (tRNA). This reaction is catalyzed by aminoacyl tRNA synthetases where each amino acid is transferred to its corresponding cognate tRNA. Because tRNAs harbor the anticodon sequence to decodes a particular mRNA codon, the specific aminoacylation of the tRNA with a cognate amino acid establishes the rules of decoding genetic code into proteins. Aminoacylated tRNAs are then delivered to ribosomes, where ribosomes in a highly organized manner need to accurately …

Population Structure And Reproductive Biology Of Monilinia Vaccinii-Corymbosi (Reade) Honey In Lowbush Blueberry In Maine, Katherine A. Ashley

Electronic Theses and Dissertations

Lowbush blueberry, Vaccinium angustifolium Aiton, is both an economically and culturally important crop in Maine, being one of the few endemic crops to North America. The fungus Monilinia vaccinii-corymbosi (Mvc) causes mummy berry disease and is a significant pathogen of both highbush (Vaccinium corymbosum) and lowbush blueberries. While impacts of this disease are not regularly documented, it is estimated that 30-50% of the yield in an unmanaged field can be lost because of Mvc. This disease is typically managed with fungicides or burning of the field during years when the field is pruned, however, the impacts to the …

Characterization Of Ethanol-Related Phenotypic Differences Between C57bl/6j And C57bl/6nj Substrains: Role Of Cyfip2?, Matthew C. Hartmann

Electronic Theses and Dissertations

The C57BL/6 (B6) mouse is the most commonly used inbred strain in biomedical research, and has served as the basis for various large-scale genetic and genomic projects. Although the parental substrain, C57BL/6J (B6J), originated at The Jackson Laboratory, isolated breeding colonies are now maintained at numerous sites. This separation has resulted in genetic drift that has led to the emergence of phenotypic differences among these colonies. For instance, B6J mice display higher levels of voluntary ethanol consumption and increased locomotor responses to psychostimulants, relative to C57BL/6N mice (B6N). Initial progress has been made in elucidating the genetic bases of these …

Thermal And Microbial Effects On Brown Macroalgae: Heat Acclimation And The Biodiversity Of The Microbiome, Charlotte Tc Quigley

Electronic Theses and Dissertations

This dissertation examines effects of stress on brown algal biology from a macroscopic scale by examining the whole aquaculture crops, and at a microscopic level by examining the macroalgal microbiome, across the vertical stress gradient of the intertidal zone and across the latitudes of their biogeographic ranges. Thermal stress negatively affected seedstock gametophytes of the kelp Alaria esculenta isolated from northern and southern locations in Maine. However, previous thermal stress had a positive effect on growth of the next-generation sporophytes. Alaria esculenta has potential as a kelp crop in Maine’s sea vegetable aquaculture sector and implementing this protocol may allow …

Tarbp2 -Mediated Post-Transcriptional Regulation Of Gene Expression During Murine Embryonic Development And Spermatogenesis, Sri Ramulu N. Pullagura

Electronic Theses and Dissertations

Micro RNAs (miRNAs), which are ~22 nucleotide (nt) long RNA molecules and several RNA binding proteins (RBPs) engage in an RNA dependent post-transcriptional gene silencing process known as RNA interference (RNAi). In the canonical miRNA biogenesis pathway, an enzyme known as DICER cleaves the ~70nt pre-miRNA to a ~22nt long miRNA that is loaded into the RNAi effector mechanism, the RNA induced silencing complex (RISC).

Several in vitro studies provide suggestive evidence that mammalian double stranded RNA binding proteins (dsRBPs), such as TARBP2, act as DICER cofactors in miRNA processing and RISC loading to promote RNAi activity. A screen attempting …

Precision Gene Therapy For Charcot-Marie-Tooth Disease: From Identifying Genetic Modifiers To Developing Allele-Specific Therapies, Kathryn H. Morelli Ph.D.

Electronic Theses and Dissertations

Charcot-Marie-Tooth Disease (CMT) is a clinically and genetically heterogeneous collection of inherited peripheral neuropathies generally characterized by progressive muscle atrophy, weakness, and loss of sensation in the distal extremities. This inherited disorder, for which there is currently no curative treatment, is the most common inherited disease of the peripheral nervous system, affecting 1:2,500 individuals worldwide.

Clinically, CMT is broadly divided into demyelinating (type 1) and axonal (type 2) forms. Although the clinical presentation can vary greatly in severity and progression within individual patients. Genetically, over 1,000 mutations in over 80 loci in the human genome have been linked to specific …

Prospective Associations Of Homocysteine, Executive Function, And Depressive Symptoms, Peter J. Dearborn

Electronic Theses and Dissertations

Associations of cardiovascular risk factors, cognitive performance, and depressive symptoms have been well established. However, the directionality of these associations as well as the specificity of these associations with respect to executive function are less clear. Additionally few studies have determined whether genetic risk factors, such as apolipoprotein-E4 (APOE-E4) genotype, and age moderate the associations of cardiovascular risk factors such as homocysteine with changes in depressive symptoms and how these associations may be mediated by cognitive performance. The primary aim of this study was to analyze the bidirectional associations of a full range of cognitive domains and symptoms of depression …

Molecular And Pathological Analyses Of Three New Mouse Mutations That Affect Ear Development And Function, Cong Tian

Electronic Theses and Dissertations

This dissertation presents three new mouse models that help to study the functions of Enpp1, Atp6v1b1, and Tbx1 for ear development and function. asj (aging with stiffened joints) carries a missense mutation in the mouse Enpp1 gene. Enpp1 encodes the enzyme ENPP1 that regulate soft-tissue calcification and bone mineralization, and is associated with generalized arterial calcification of infancy and hypophosphatemic rickets in human patients. asj mutant mice show severe middle ear infection and tissue calcification, which provide a new mouse model to study otitis media and tympanoscleorosis. Atp6v1b1 encode a protein that is a subunit of the V-ATPase …

The Biogeographic Origins And Trophic Ecology Of Maine’S Island Red-Backed Salamanders (Plethodon Cinereus), Nikko-Ideen Shaidani

Electronic Theses and Dissertations

Island populations of terrestrial species have an increased potential, compared to mainland populations, to adapt and diverge, as these populations often are isolated with respect to gene flow from other populations and may be subjected to novel pressures. Indeed, extended isolation of individuals can elicit dramatic changes within populations and is recognized as a common driver of speciation. It is for these reasons that island populations are often a priority for conservation. Plethodontid salamanders are among the most terrestrial of Maine’s amphibians and are not tolerant of prolonged exposure to seawater, and yet, they are found on a number of …

Effects Of Melatonin On Heartbeat And Possible Identification Of A Melatonin Receptor In Drosophila Melanogaster, Tricia L. Vankirk

Electronic Theses and Dissertations

Chapter 1 of this manuscript is a literature review that serves as an introduction to the entire dissertation. Chapter 2 examines the effects of the melatonin injection on heart rate and rhythmicity in Drosophila melanogaster Canton-S (wild-type) pupae and pupae bearing a variety of heart mutations. Chapter 3 investigates further the possible mechanisms of melatonin’s ability to increase heart rhythmicity without significantly affecting heart rate. A melatonin antagonist, luzindole; a high-affinity melatonin agonist, 2-iodomelatonin and RNAi techniques are used to identify a possible melatonin receptor in Drosophila melanogaster.

An appendix contains a previously published manuscript detailing experiments performed at the …