Digital Commons Network^™

Sexual Dimorphism In A Mouse Model Of Dry Eye Disease, Neal Mecum

Electronic Theses and Dissertations

Dry eye can result from multiple causes, including a reduction in the quantity or altered composition of tears. The lacrimal gland is the major supplier of the aqueous tear components, including water, electrolytes, and proteins. Reduced output from the lacrimal glands results in aqueous tear deficiency, a specific subclass of dry eye disease (DED) marked by inadequate tear volume. The prevalence of DED is 1.5-2 times greater in women than men, yet a comprehensive comparison of dry eye symptoms in male and female animals in an animal model of DED has not been performed. We excised the lacrimal gland to …

Spruce Budworm Defoliation Dynamics And Its Influence On The Acadian Forest, Cen Chen

Electronic Theses and Dissertations

Spruce budworm (SBW; Choristoneura fumiferana (Clem.)) is the primary forest defoliator in North America. SBW defoliation has affected tens of millions ha of forests during its periodic outbreaks and caused severe growth reduction and mortality of spruce-fir (Picea-Abies) species. Evaluating these damaging effects of SBW defoliation requires understandings of the variation and dynamics of defoliation, as well as trees' variable responses to defoliation in consideration of various tree- stand-, and site-level factors. In this dissertation, we developed statistical models to 1) evaluate influences of SBW defoliation on spruce-fir stand dynamics of annual volume net growth, mortality, …

Towards A Unified Disease Mechanism For Trna Synthetase-Mediated Peripheral Neuropathy, Emily L. Spaulding

Electronic Theses and Dissertations

Charcot-Marie-Tooth disease (CMT) is a debilitating inherited peripheral neuropathy resulting in progressive distal muscle atrophy and loss of sensation. CMT is genetically heterogeneous, with mutations in over 80 different genes leading to demyelinating or axonal forms. There are genetically similar subgroups, including the largest protein family implicated in the disease, the tRNA synthetases (ARSs). ARSs are responsible for aminoacylation of tRNAs during translation and are therefore ubiquitously expressed and essential proteins. Dominant mutations in at least five ARSs cause axonal forms of CMT. How mutations in ARSs cause CMT is unclear, however, the similar clinical presentation of patients suggests shared …

Validation Of A Fluorescence-Based Bacteria Enumeration And Viability Determination Method Using Image Cytometry, Matthew R. Hodgkin

Electronic Theses and Dissertations

Craft beer production in the United States has been increasing significantly in recent years. As production and participation in the industry increases, so have consumer demands for more beer options. Breweries have met this call with experimentation of ingredients in their beer and also the styles they brew. One such beer, the sour beer, is an example of this experimentation and new product development. Sour beers are a style that differ from most other beers by how they are manufactured. Instead of being fermented with only yeast, both a lactic acid-producing bacteria and yeast are used. With increased competition amongst …

The Effects Of Sediment Acidification And Temperature On The Immune Capacity Of The Atlantic Jackknife (Razor) Clam (Ensis Leei M. Huber, 2015), Brian Preziosi

Electronic Theses and Dissertations

Sediment acidification has been shown to negatively impact clams of economic importance such as the soft-shell clam, Mya arenaria Linnaeus, 1758, and hard clam, Mercenaria mercenaria (Linnaeus, 1758). Effects of sediment acidification on razor clams, including the Atlantic jackknife clam Ensis leei M. Huber, 2015, are unknown. E. leei has been identified as a species with potential for aquaculture operations on the New England coast. E. leei may be resilient to acidification and thus persist in acidified sediments where other clams cannot. To this end, the impact of acidified surface sediment on the internal immune capacity of adult (mean shell …

The Potential For Dickeya Dianthicola To Be Vectored By Two Common Insect Pests Of Potatoes, Jonas K. Insinga

Electronic Theses and Dissertations

Dickeya dianthicola (Samson) causing blackleg and soft rot was first detected in potatoes grown in Maine in 2014. Previous work has suggested that insects, particularly aphids, may be able to vector bacteria in this genus between plants, but no conclusive work has been done to confirm this theory. In order to determine whether insect-mediated transmission is likely to occur in potato fields, two model potato pests common in Maine were used: the Colorado potato beetle (Leptinotarsa decimlineata Say) and the green peach aphids (Myzus persicae Sulzer). Olfactometry and recruitment experiments evaluated if either insect discriminates between infected and …

Evaluating The Occurrence Of Age-Related Peripheral Neuropathy In Het3 Mice And Development Of A Whole Tissue Imaging Technique For Analyzing Total Innervation In The Subcutaneous Adipose Depot, Jake Willows

Electronic Theses and Dissertations

Adipose tissue can be characterized as either being a white (energy storing) depot or a brown (energy expending) depot and both have been found to contain dense networks of neural innervation. This adipose nerve supply regulates numerous metabolic functions and likely plays an important role in the function of adipose blood vessels. Recently our lab has shown in the C57BL/6 mouse model that peripheral neuropathy, or the dying back and dysfunction of the nerves in the superficial tissues such as the skin, can extend into the subcutaneous adipose tissue in conditions commonly associated with the neuropathic phenotype (i.e. diabetes, obesity, …

Fish Passage And Hydropower: Investigating Resource Agency Decision-Making During The Ferc Hydropower Relicensing Process, Sarah Vogel

Electronic Theses and Dissertations

Hydropower dams represent a significant challenge for the successful migration of sea-run fish, many species of which are in decline. Most hydropower dams in the United States are regulated by the Federal Energy Regulatory Commission (FERC), an independent federal agency responsible for granting 30 to 50-year licenses to projects for their continued operation. Licenses typically include conditions for the conservation of sea-run fish such as fish passage construction, operational changes, monitoring of effectiveness, and other mitigative conditions. While FERC remains the primary authority in licensing, the current regulatory framework stipulates input from other federal and state resource and regulatory agencies, …

Getting Over The Dam: Overcoming Institutional Barriers To The Recovery Of Atlantic Salmon By Navigating The Social-Science/Policy Interface, Melissa E. Flye

Electronic Theses and Dissertations

The term governance has undergone somewhat of an evolution since its inception, originally describing the act of governing, it has come to represent a more collaborative form of governing which is distinct from hierarchical control models (Marin and Mayntz, 1991). Collaborative governance refers to the systems associated with public policy decision making and resource management which span the jurisdictional boundaries of public agencies, levels of government, and/or public and private spheres in order to pursue a public policy goal or outcome (Emerson et al., 2012). Environmental management is often considered an inherently collaborative effort, as ecological systems and species rarely …

Identification Of Chromatin Regulators Perturbed In Hematopoietic Stem And Progenitor Cell Aging, Eraj S. Khokhar

Electronic Theses and Dissertations

As lifespan is increasing globally, there is a critical need to identify strategies to extend healthspan and prevent chronic diseases into older age. The long-term goal of my research is to identify novel strategies to ameliorate aging-induced decline in hematopoietic stem cell (HSC) function. HSCs give rise to all mature blood and immune cells. With age, HSCs undergo defects in their differentiation ability which correlates with a decline in immune function. Comprehensive knowledge of gene regulatory and epigenetic mechanisms underlying this defect is a barrier to developing therapies to ameliorate aging-associated decline in HSC function. Therefore, my project focuses on …

Spatial And Temporal Variation In The Aquatic Invertebrate Community Structure Of Rock Pools Along The Penobscot River, Maine, Chase R. Gagne

Electronic Theses and Dissertations

Pools of water that form in the fissures and depressions of rock outcrops, known as rock pools, are fairly common aquatic habitats that can easily be found along the rocky banks of many of Maine’s major rivers. In general, rock pools and the aquatic invertebrates inhabiting them have received little research attention and, though ubiquitous, have never been studied in Maine. My research addressed this knowledge gap by surveying 40 rock pools at four sites along the Penobscot River in Maine. The rock pools themselves had highly variable environmental characteristics and differed across sites and over time, especially in hydroperiod. …

Dynamic Regulation Of G-Protein Signaling, William C. Simke

Electronic Theses and Dissertations

G protein-coupled receptors (GPCRs) are involved in numerous signaling processes ranging from neuronal growth to immune cells tracking invaders. GPCR signaling plays a role in many human diseases and thus GPCRs are important drug targets. Yeast respond to mating pheromone using a GPCR signaling system homologous to those used in humans to polarize their cytoskeleton toward the pheromone source. This is accomplished by initializing a MAPK signaling cascade to arrest the cells in mitosis and upregulate expression of chemotropic proteins. Pathway desensitization is accomplished by the Regulator of G-protein Signaling (RGS). RGS abrogates signaling by binding to the active GPCR, …

Microbial Diversity Of The Symbiotic Colony Of Bacteria And Yeast (Scoby) And Its Impact On The Organoleptic Properties Of Kombucha, Danielle L. St-Pierre

Electronic Theses and Dissertations

Kombucha is an effervescent fermented tea beverage that is gaining popularity for its probiotic nature and purported health benefits. The market for kombucha is expected to reach $1.8 billion by the year 2020. The composition of microbes that compose the symbiotic colony of bacteria and yeast (SCOBY) is highly variable with some species commonly found from the Gluconobacter, Acetobacter, Zygosaccharomyces, Saccharomyces, and Schizosaccharomyces genera.

It was hypothesized that different SCOBYs, obtained from different sources would vary in microbial diversity and produce different biochemical and flavor profiles in the resulting beverage over several generations. Kombucha is a fermented …

Deep Benthic Coral Habitats Of Glacier Bay National Park And Preserve, Alaska, Elise C. Hartill

Electronic Theses and Dissertations

Glacier Bay National Park and Preserve in Southeast Alaska is a system of fjords that presents an ideal natural laboratory to study terrestrial, aquatic and marine patterns of succession due to its unique and recent history of deglaciation. The patterns of deep benthic community assemblages in the fjords of Glacier Bay were investigated by quantitative assessment of underwater photo-quadrats collected using a remotely operated vehicle. The percent cover and diversity of species were lowest near the glaciated heads of the fjords and highest in the Central Channel and at the mouths of the fjords of Glacier Bay, where oceanographic conditions …

The Dispersal Pattern Of Thekopsora Minima In Wild Blueberry Determined By A Molecular Detection Method, Nghi Nguyen

Electronic Theses and Dissertations

Blueberry rust caused by Thekopsora minima is a common disease in wild blueberry (Vaccinium angustifolium) and other Vaccinium genera. Understanding the spore dispersal pattern and disease cycle of fungal pathogens in wild blueberry is crucial for the development of a more efficient disease management program. Molecular assays for rapid detection and quantification of Thekopsora minima were developed to be incorporated with a spore trap sampling method and weather data collection to examine spore dispersal pattern and production in three different fields: Blueberry Hill Farm in Jonesboro, East Machias, and Spring Pond in Deblois, Maine, in three years 2014, …

Identification Of High-Risk Food Coping Strategies Of Maine Food Pantry Clients, Kathryn Cutting

Electronic Theses and Dissertations

Food coping strategies are strategies adopted by individuals in order to obtain enough food for themselves and their family. Food coping strategies can range from using coupons (couponing) and buying in bulk to skipping meals and stealing food. Although not all strategies are considered to be high risk, all strategies should be accounted for so that nutrition education programming caters to strategies that individuals are employing. This topic has not been widely researched in the United States. The purpose of this study was to identify common food coping strategies of food pantry clients across nine counties in Maine, explore identified …

Intravital Imaging In A Zebrafish Model Elucidates Interactions Between Mucosal Immunity And Pathogenic Fungi, Linda S. Archambault

Electronic Theses and Dissertations

Candida yeasts are common commensals that can cause mucosal disease and life-threatening systemic infections. While many of the components required for defense against Candida albicans infection are well established, questions remain about how various host cells at mucosal sites assess threats and coordinate defenses to prevent normally commensal organisms from becoming pathogenic. Using two Candida species, C. albicans and C. parapsilosis, which differ in their abilities to damage epithelial tissues, we used traditional methods (pathogen CFU, host survival, and host cytokine expression) combined with high-resolution intravital imaging of transparent zebrafish larvae to illuminate host-pathogen interactions at the cellular level …

Mountain Livelihoods In A Time Of Change: A Case Study Of Upper Mustang In Nepal, Sandesh Shrestha

Electronic Theses and Dissertations

A case study was conducted in a remote Himalayan village—Yara—in the Upper Mustang region of Nepal. The goal of this study was to understand and assess the livelihood strategies of local people in the village. The study focused on understanding the socio-economic and environmental driving factors of livelihood vulnerability, prevalent livelihood activities, emergent livelihood strategies, and resulting livelihood outcomes in the village. We used multiple data generation methods, which included both qualitative social science and quantitative biophysical components. For the qualitative component, we utilized multiple data generation methods including key informant interviews, semi-structured household interviews, group discussions, and field observations. …

Social-Ecological Heterogeneity Shapes Resilience Of Small-Scale Fisheries: An Interdisciplinary Analysis Of The Mexican Chocolate Clam Fishery In Loreto, Mexico, Kara E. Pellowe

Electronic Theses and Dissertations

All benefits provided by natural systems are embedded within coupled social-ecological systems (SESs). Fisheries are clear examples of SESs: through fishing, humans affect ecosystem structure and functioning, and in turn, receive benefits, including sustenance, employment, and cultural value. Resilience, the ability to maintain structure and function in the face of change, is key to sustaining the social and ecological components of fisheries-related SESs and their interactions. Many factors contribute to resilience, including heterogeneity. By identifying heterogeneity in these complex systems, we are better able to understand the capacity of fishery-related SESs to adapt to change, and contribute to management that …

Neuromuscular Development And Phenotypic Variation In Zebrafish Models Of Dystroglycanopathy, Erin Bailey

Electronic Theses and Dissertations

Skeletal muscle is highly conserved among vertebrates and is essential for strength and locomotion. This tissue becomes integrated with the skeletal system via tendons at the myotendinous junction and with the nervous system at the neuromuscular junction. Both of these specialized junctions are rich in extracellular matrix, a protein scaffold that occupies the extracellular space of cells. Skeletal muscle is also highly plastic and can grow in size (hypertrophy) or lose mass (atrophy) in response to genetic or environmental cues. Muscle atrophy is found in individuals battling a number of neuromuscular conditions, including muscular dystrophy. Muscular dystrophies are a suite …

Cellular And Molecular Mechanisms Of Mapk Signaling During Jc Polyomavirus Infection, Jeanne Dushane

Electronic Theses and Dissertations

As obligate intracellular parasites, viruses must infect a host-cell and requisition cellular machinery for viral replication. JC polyomavirus (JCPyV) is a ubiquitous human pathogen that can cause a lytic infection in glial cells of the central nervous system in immunocompromised individuals. In order to initiate infection however, the virus must alter prototypical cellular processes that promote cellular homeostasis. The main driver of these processes are signaling pathways, the means by which the cell interacts and responds to the extracellular environment. Many signaling cascades are responsible for promoting growth, responding to pathogens, initiating differentiation, or inducing cell death. Through the works …

The Association Of Late-Life Depression, Cognitive Functioning, And Sleep Disorder In Aging, Jessica B. Aronis

Electronic Theses and Dissertations

The continuing growth in the demographic of aging individuals in the United States creates concern for diseases of aging that are chronic, notably unipolar depressive disorders. The high rates of depression in the aging population are a concern because of the strong association between late-life depression and cognitive impairment. Poor cognitive functioning is a hallmark of aging related neurological disorders, the most prevalent being Alzheimer’s Disease (AD). Sleep disorder is a core symptom of depression, and is definitively associated with the development of mild cognitive impairment (MCI), the prodrome of AD. MCI is also characterized by similar types of sleep …

Understory Response To Gap-Based, Multi-Aged Silviculture, Maggie R. Mansfield

Electronic Theses and Dissertations

The ubiquity of managed forests has created a demand for management practices that simultaneously meet traditional management goals and maintain biodiversity. Ecological forestry, which emulates the outcomes of natural disturbances, is assumed to enhance native species survival by creating conditions similar to those under which species have long survived. We assessed this assumption by exploring the herbaceous plant community response to 20 years of gap-based, multi-aged silviculture treatments. Additionally, we assessed the ability of the treatments to meet silvicultural objectives by exploring trends in tree regeneration. The Acadian Forest Ecosystem Research Project (AFERP) is a replicated study established in 1995 …

Comparing Independent Approaches To Estimate Age At Size Of The Jonah Crab (Cancer Borealis): Corroborating Gastric Mill Band Counts As A Direct Aging Method, Carlton Huntsberger

Electronic Theses and Dissertations

Knowing the age of an organism is essential in understanding the dynamics and management of wild populations. Age determination has been an especially long-standing challenge in the study of crustaceans, since they posed a unique challenge, shedding all calcified structures with each molt. The Jonah crab (Cancer borealis), is one of many commercially harvested crustaceans for which no absolute aging method has yet been established. It is an ecologically important species and a newly managed fishery in New England and Atlantic Canada. The recent increase of commercial fisheries for this species has highlighted the large data gap of …

Assessing The Effectiveness Of The Expanded Food And Nutrition Education Program On Diet Quality As Measured By The Healthy Eating Index 2005, Sarah A. Perkins

Electronic Theses and Dissertations

Background:The Expanded Food and Nutrition Education Program (EFNEP) is a federally funded program through the United States Department of Agriculture that offers nutrition education to low income families across the U.S.

Purpose:This study assessed the effectiveness of Maine EFNEP on food-related behavior change and diet quality as measured by the Healthy Eating Index-2005 (HEI). This study also explored the relationship between the results on the HEI and participation in food assistance programs such as Supplemental Nutrition Assistance Program (SNAP) and Women, Infants, and Children (WIC), as well as the number of hours spent in the program.

Methodology:This study was a …

Efficacy Of Alternative Sanitization Methods On Wild Blueberries And Fresh Cut Cantaloupe, Selena Callahan

Electronic Theses and Dissertations

In the last decade, outbreaks linked to the consumption of contaminated fresh produce have increased mitigation efforts to minimize the risks associated with these products. Due to the lack of a kill step during processing of ready-to-eat (RTE) foods, good manufacturing practices (GMP’s), and sanitization are the key prevention areas most commonly used to control these risks. Many factors must be considered by processors for successful intervention such as sanitizer type, method of application, duration of application, and concentration. Additionally, product considerations such as water content, pH, and bacterial harborage sites can contribute greatly to how effective an applied treatment …

Response Of Early Life Stage Homarus Americanus To Ocean Warming And Acidification: An Interpopulation Comparison, Maura K. Niemisto

Electronic Theses and Dissertations

Anthropogenic carbon released into the atmosphere is driving rapid, concurrent increases in temperature and acidity across the world’s oceans, most prominently in northern latitudes. The geographic range of the iconic American lobster (Homarus americanus) spans a steep thermal gradient and one of the most rapidly warming oceanic environments. Understanding the interactive effects of ocean warming and acidification on this species’ most vulnerable early life stages is important to predict its response to climate change on a stage-specific and population level. This study compares the responses of lobster larvae from two sub-populations spanning New England’s north-south temperature gradient (southern …

Assessing The Mechanisms And Implications Of Altered Carbon Cycling In Arctic And Boreal Lakes, Rachel Fowler

Electronic Theses and Dissertations

Dissolved organic carbon (DOC) is an important component of lake ecology, as it contributes to light attenuation and carbon cycling. In recent years, DOC declined in a suite of lakes in Greenland. I performed experiments to test potential mechanisms of DOC loss. The tested mechanisms did not reduce DOC concentration, but DOC composition was affected. I also paired water quality data with meteorological observations to evaluate effects of climate drivers on lake variables. The lake variables were temporally coherent and associated with patterns of mean annual precipitation.

In the northeastern U.S., recovery from acidification and climate change have contributed to …

Paper Structure Formation Simulation, Tyler R. Seekins

Electronic Theses and Dissertations

On the surface, paper appears simple, but closer inspection yields a rich collection of chaotic dynamics and random variables. Predictive simulation of paper product properties is desirable for screening candidate experiments and optimizing recipes but existing models are inadequate for practical use. We present a novel structure simulation and generation system designed to narrow the gap between mathematical model and practical prediction. Realistic inputs to the system are preserved as randomly distributed variables. Rapid fiber placement (~1 second/fiber) is achieved with probabilistic approximation of chaotic fluid dynamics and minimization of potential energy to determine flexible fiber conformations. Resulting digital packed …

Landscape Pattern And Wild Bee Communities In Maine, Brianne Du Clos

Electronic Theses and Dissertations

Commercial production of lowbush blueberry (Vaccinium angustifolium Aiton) in Maine relies primarily on managed honeybee hives; however, naturally occurring wild bees are more efficient pollinators of the crop. Wild bees have short foraging distances and must nest near crop fields to provide pollination services. After crop bloom, the surrounding landscape must provide sufficient forage to maintain wild bee populations for the remainder of the growing season. Lowbush blueberries in Maine are produced in a mixed-use landscape with two distinct landscape contexts. Here, we document bee communities and habitat resources (nesting and floral) in power line rights-of-way and eight land …