Life Sciences Commons^™

Strategies To Promote Value And Resilience In The American Lobster (Homarus Americanus) Industry, Nicole Orminski

Electronic Theses and Dissertations

The American lobster (Homarus americanus) fishery is the most valuable single-species fishery in the United States and Canada (DFO, 2021; NOAA Fisheries, n.d.). Coastal communities on both sides of the border rely on the American lobster supply chain, which economically links the two countries with one another and with other countries around the globe. Ongoing disruptions (or shocks) threaten the functionality of the supply chain, and increased globalization leads to greater exposure to shocks as they are transmitted between systems. One research study described in this thesis aims to add value to the industry via post-harvest treatment of …

Educating Dietetics Students About The Nutritional Concerns Of Older Adults, Lily Brickman

Electronic Theses and Dissertations

The percentage of individuals in the United States who fall within the 65 years and older cohort is anticipated to increase substantially over the next decade due to the large baby boomer generation aging into this category by 2030. Consequently, the healthcare demands of older adults are expected to increase, and medical and healthcare providers must be educated and prepared to meet the unique needs of this population. The purpose of this study is to help learn why interest in FSN 406 Nutritional Care of Older Adults has been so low since its inception in 2020, and whether other institutions …

Barriers To And Opportunities For Adoption In Maine’S Aquaculture Industry, Caitlin Cleaver

Electronic Theses and Dissertations

Aquaculture, or the farming of marine species, can diversify coastal economies, but development of this industry is hindered by negative perceptions or regulatory constraints. Commercial fishers are logical adopters of aquaculture, but can also mount opposition to its growth. This dissertation utilized innovation theory to understand fishers’ perceptions of and willingness to adopt aquaculture and drivers of and barriers to scallop aquaculture development in Maine (USA). Through a mail survey, lobster fishers’ perceptions of Maine’s aquaculture industry and their willingness to adopt aquaculture were assessed (Chapter 2). Individuals who were more satisfied with government management of aquaculture held more positive …

Form And Risk Class Distribution And Its Effect On Estimated Product Ratios In Commercial Species Commonly Found In Northeastern Forests And A Comparative Analysis Of Contrasting Field Inventory Methodologies, Ryan Smith

Electronic Theses and Dissertations

Estimating product ratios in hardwood forests is difficult due to the highly complex stem forms and diverse growth and regeneration strategies found in hardwood species. This is of particular concern for landowners with large ownerships requiring robust product potential estimates as part of both short-term tactical harvest planning and long-term growth and yield projections. Hardwood-dominated forests are generally managed for high-value sawlog and veneer products. This makes it increasingly important to identify strategies for improving hardwood management to meet economic (maximizing sawlog recovery) and ecological (maintaining healthy and diverse forests) goals.

This study seeks to achieve two primary goals. The …

Using Reflex Actions To Predict Delayed Post-Harvest Mortality Of American Lobster (Homarus Americanus) In Maine’S Lobster Supply Chain, Cassandra Leeman

Electronic Theses and Dissertations

In live seafood industries, maintaining product quality and survivorship are critical aspects of the supply chain infrastructure. Post-harvest mortality in the American lobster (Homarus americanus) fishery can result in a significant loss in revenue for the largest single species fishery in North America. In Maine, the wholesale lobster distribution supply chain directly and indirectly supports state and local economies, providing almost $1 billion in revenue and dominates the fishery, producing 82% of the total lobster landings in the USA (Donihue, 2018; NOAA, 2021). However, at least 2% of the lobster landed in Maine die before they reach consumers, representing an …

Improving Use Of Soil Health Practices In Kansas: A Study Of Barriers To Adoption And Novel Incentive Programs, Sara Kelemen

Electronic Theses and Dissertations

As climate change continues to affect agroecosystems, farm resilience will become increasingly important. To feed a growing global population, the future of agriculture must be secure and ultimately, sustainable. Use of soil health practices can increase farm resilience through improved provision of ecosystem services. Not only does this benefit the farm agroecosystem, it can also improve also agronomic outcomes while also improving landscape scale ecological conditions. It can also can have positive impacts on profitability. The benefits to use of soil health practices are well documented, yet rates of adoption in the United States remain relatively low. Therefore, research must …

Understanding The Impacts Of Anthropogenic Effects An Habitat Variability Interactions On Maine's Rocky Intertidal Ecosystem, Laura Braun

Electronic Theses and Dissertations

The rocky intertidal ecosystem is an important ecological and cultural aspect of the picturesque Maine coast, playing a vital role in not only Maine’s coastal ecosystem, but also to Maine’s economy. It’s distinct community structure along the sharp elevational gradient and the presence of daily stressors (wave action, heat, and desiccation), make the rocky intertidal ecosystem an important model ecosystem to monitor for effects from anthropogenic impacts. In this thesis, I describe attempts to monitor and understand the impacts of two of these anthropogenic impacts on this system: climate change and industrial harvesting of Ascophyllum nodosum along Maine’s coast. For …

Quantitative Silviculture Of Northern Conifers, David G. Ray

Electronic Theses and Dissertations

Quantitative tools used to guide the management of important northern conifer species require updating and refinement to address changes in the contemporary resource and evolving objectives of ownership. This work builds on an extensive body of knowledge about stand density management and innovates some new approaches. In sum, the three chapters presented herein: 1) seek to strengthen and more fully articulate arguments for adopting relative density as a primary metric of stand density assessment, 2) quantify minimum stand densities to achieve full site occupancy and argue for more parity with treatment of maximum stand density, and 3) present an empirically …

Genetic Characterization Of Centromere-Mediated Uniparental Genome Elimination In Arabidopsis, Diana Spencer

Electronic Theses and Dissertations

The production of haploids through crossing was first discovered from instances of interspecies crosses in Nicotiana spp. in 1924. Since then, haploid induction crosses has been used to improve plant breeding programs and commercially utilized in a number of crop industries. The generation of doubled haploid instantaneously creates a pure homozygous line, therefore eliminating the need for several generations of inbreeding. There are several pathways to induce haploids in plants: of these methods, centromere-mediated genome elimination pathway engenders the highest haploid induction rate (HIR) with up to 45% in Arabidopsis compared to 15% through phospholipase-mediated haploid induction in maize. Centromere-mediated …

Carbon Dioxide Emissions From Deadwood In Forests Of The Northeastern United States, Zoe Read

Electronic Theses and Dissertations

As the climate changes, understanding the sources and sinks of greenhouse gases such as carbon dioxide (CO₂) is increasingly important. However, several components of the carbon cycle within forests remain poorly understood. For example, knowledge gaps exist in our understanding of CO₂ emissions from coarse woody material (CWM; logs and stumps), including how emissions change over time, how they are influenced by environmental variables, and how they compare to soil and ecosystem-level CO₂ emissions.

To fill these knowledge gaps, we examined CO₂ emissions from CWM at three sites. We sampled 18 red spruce (Picea …

A Sky Island Perspective: New England Alpine Plant Distributions Across The Region, Andrea Tirrell

Electronic Theses and Dissertations

Alpine ecosystems around the globe are at risk due to climate change, human disturbance, and habitat loss. New England alpine zones are small and fragmented, which could make them vulnerable to global change. However, the persistence of tundra relics throughout the Holocene suggests the persistence of these communities in microclimate refugia. Assessing the near-term vulnerability of alpine plant communities is challenged by a lack of standardized, repeat surveys and long-term monitoring data, which presents a challenge for the many agencies monitoring New England’s alpine zones. Island biogeography theory predicts that alpine species richness is a function of area, but this …

Seabirds As Proxies For Past El Niño Events In Coastal Peru: An Archaeo-Ornithological Approach, Heather A. Landazuri

Electronic Theses and Dissertations

This thesis sets an initial foundation for an archaeo-ornithological approach to understanding past El Niño events on the coast of Peru and the use of avifaunal remains as proxies for ecological conditions. Although faunal remains from archaeological sites do not provide exact representations of past environmental conditions, and bird remains can be especially challenging environmental indicators, their presence does reflect decisions made by human occupants in response to environment. Additionally, zooarchaeological data offer a reflection of past animal availability and use, much of which is at least in part determined by environmental conditions. Here I examine the extent to which …

Ecological Implications Of Intraspecific Behavioral Variation In A Small Mammal Community, Allison Brehm

Electronic Theses and Dissertations

Variation among individuals is at the root of all evolution by means of natural selection. However, only in recent years has intraspecific behavioral variation been embraced as a potential driver of community and ecosystem processes, rather than considered statistical noise. Animal personalities, or behavioral differences between conspecifics that are consistent across time and contexts, are one such form of variation that has received considerable attention in the last two decades. Investigations of the ecological and ecosystem consequences of personality variation is at the current forefront of the field, but much work on this topic remains conceptual. Here, I apply large-scale …

Telomerase Reverse Transcriptase Marks A Novel Population Of Adult Stem Cells In The Mouse Brain That Respond To Metabolic Interventions By Modulating Adult Brain Plasticity, Gabriel S. Jensen

Electronic Theses and Dissertations

Telomerase reverse transcriptase (TERT) is expressed by quiescent adult stem cells (qASC) in numerous adult murine and human tissues but has never been explored in the adult brain. Here, these data demonstrate that TERT+ cells in the adult mouse brain represent a novel population of multipotent qASCs. TERT+ cells were localized to numerous classical neuro/gliogenic niches including the ventricular-subventricular zone, hypothalamus and olfactory bulb, as well as newly discovered regions of adult tissue plasticity such as the meninges and choroid plexus. TERT+ cells expressed neural stem cell markers such as Nestin and Sox2, but not markers of activated stem/progenitor cells, …

The Rapid Enumeration Of A Mixed Culture Of S. Cerevisiae & L. Plantarum In Beer Using Image-Based Cytometry, Kevin M. Kennedy

Electronic Theses and Dissertations

Mixed cultures are prevalent in the food industry. From sour beer to sourdough bread, mix culture popularity is growing. A number of microbiological mixtures are used in these unique fermenting processes to create distinctive flavor profiles of consumers’ favorite foods. Although mixed cultures seem ubiquitous, they are often not well enumerated. The aim of this thesis was to create a novel rapid image-based cytometry method to enumerate mixed cultures in beer. Imaged-based cytometry can be used to rapidly enumerate mixed microbial cultures, as opposed to traditional plate counting methods that can take days to grow and count. A novel method …

Genetic Sources Of Resistance To Potato Blackleg Soft Rot Caused By Dickeya Dianthicola, Lucas K. Heroux

Electronic Theses and Dissertations

Solanum tuberosum L. is the world's most important non-cereal food crop, capable of producing more food per land unit on less water than any other crop. Only rice, wheat, and maize are produced in larger quantities than potato. The potato tuber, a modified stem turned storage organ is nutrient dense and a staple in diets across the world. The potato crop is expected to grow and contribute significantly to the global food supply. However, potato production has increasingly been threatened by unfavorable environmental conditions, and susceptibility to pest and disease. Perhaps the most famous of all the Irish Potato Famine …

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 …

3d Computer Modeling Offers New Insights Into Diatom Ecology, Joseph Mohan

Electronic Theses and Dissertations

Algae supply over half of the Earth’s global primary production and form the base of almost all aquatic food networks. Thus, changes in algal productivity or composition will induce profound shifts in many ecosystems. This research is guided by two questions. Herein I ask if 3D models of algae can be created accurately enough to use for research applications? If they can be accurately created, then how can these models be used to advance our understanding of functional trait evolution and paleoecology? Herein, I develop 3D computer models for estimating the volume of individual algae and their parts. I also …

Using Soil Testing Data To Examine Organic Carbon Changes During The Past 27 Years In Maine Agricultural Soils, Andrew Chase

Electronic Theses and Dissertations

Agricultural soils may act as a source or a sink for carbon (C) in the global C cycle. With rising atmospheric CO2 levels, C sequestration in soils may play an important role in climate change mitigation. Soil organic carbon (SOC) also contributes to key aspects of soil health and fertility, such as aggregation, water-holding capacity, microbial biomass, and nutrient mineralization. Although SOC may be calculated from estimates of soil organic matter (SOM) obtained by loss-on-ignition (LOI), factors such as sample clay concentration and combustion temperature introduce error into estimates of SOM. We explored the potential for an extensive collection of …

Northern White-Cedar Stand Structure, Composition, And Ecophysiology: Implications For Management And Climate Change Resilience, Katlyn Schulz

Electronic Theses and Dissertations

Low rates of regeneration and recruitment for northern white-cedar (Thuja occidentalis) have been observed in lowland forests in some parts of its range, especially in comparison to its main tree competitor, balsam fir (Abies balsamea). In addition, climate projections suggest that suitable habitat conditions for the two species will decline in the northeastern United States and adjacent Canada due to widespread warming and increased variation in the timing and amount of precipitation. As such, future climate conditions may alter the competitive dynamics of these two species, which poses a major challenge for mitigating the negative effects of climate change through …

Career Readiness Of Recently Credentialed Registered Dietitian Nutritionists, Maegan Perrault

Electronic Theses and Dissertations

This study assessed the perceptions of career preparedness of recently credentialed Registered Dietitian Nutritionists (RDNs) (< 5 years/post credential) and their experiences in undergraduate, supervised practice, and/or graduate programs. All participants were recruited from a randomized sample from the databank of the Commission on Dietetic Registration (CDR). Participants were recently credentialed RDNs (≤5 years) from the United States (U.S). A survey was designed to evaluate the RDNs perceived ability to perform the 2017 Accreditation Standards for Nutrition and Dietetics Internship Program competencies as a working RDN. Participants were also invited to share their insights by answering open-ended questions regarding their experiences as a student in undergraduate, supervised practice, and/or graduate programs. Survey responses were analyzed overall and were grouped into six domains of practice, corresponding to the Standards of Professional Practice (SOPP) domains of the Academy of Nutrition and Dietetics. The level of education, type of undergraduate degree and type of dietetic internship were evaluated for their impact on perceived career preparedness overall and within the domains of the SOPPs. Respondents agreed that they felt prepared overall to practice as an RDN in the work setting as indicated by a mean score of 2.05 (SD=0.63). Respondents felt least prepared in the competency of “analyzing quality financial and productivity data for use in planning” M= 3.16 (SD=1.66). Conversely, respondents strongly agreed that they were able to “incorporate critical thinking in overall practice” M=1.48 (SD=.60) and “practice according to the Code of Ethics” M=1.48 (SD=.64). The domain rated strongest among respondents was Domain 2: Competence and Accountability, M=1.72 (SD = 0.56). The domain with the weakest score was Domain 6: Utilization and Management of Resources M=2.93 (SD = 1.31). There were no significant differences in perceived career preparedness overall, or by domains of practice in regard to the level of education, type of undergraduate degree, and type of dietetic internship. Knowledge gaps were identified in clinical experiences and business management. In conclusion, recently credentialed RDNs in the US who have completed ACEND® programs feel ready to practice. The type of dietetic internship, level of education, and type of undergraduate degree were not significant factors in their perceived career preparedness overall or by domain of practice. The domain of management of resources and the theme of business management were consistently the areas identified as knowledge gaps. These areas should be improved upon within dietetic programs at all levels to ensure students continue to feel prepared to work in the dynamic field of healthcare.

Regulation Of Line-1 In Developing Oocytes And The Impact On The Ovarian Reserve, Rose Besen-Mcnally

Electronic Theses and Dissertations

In humans and mice, the ovarian reserve (OR) is established during a lengthy process that starts during early embryogenesis with germ cell specification and culminates in the first weeks after birth when primordial follicles (PF) are formed. OR establishment is an important process which influences the fertile lifespan and fecundity of the individual. Fetal oocyte attrition (FOA) has been identified as a critical developmental event that regulates how many oocytes survive and contribute to the final OR. In addition to FOA, OR size and quality also depend on efficiency of meiotic recombination. Chromosome asynapsis and unrepaired meiotic double-strand breaks (DSB) …

Contact Dewatering Of Cellulose Nanofibers For Biopolymer Composite Applications, Alexander Collins

Electronic Theses and Dissertations

Cellulose Nanofibrils (CNFs) are promising materials for reinforcement of polymer matrices attributable to their impressive physical and mechanical properties, as well as their biodegradability. However, the utilization of these materials in composites is made challenging by the water content of CNF slurries, the tendency of CNFs to agglomerate as they dry, and incompatibility between hydrophilic CNFs and hydrophobic polymer matrices. The most commercially viable drying methods to produce small-scale dry CNFs, such as spray drying, are very energy intensive, can only dry the materials down to micron-scale agglomerates, and do not preserve fibrillar aspect ratios. “Contact dewatering,” or the removal …

Biophysical Interactions And Social Perceptions Of Ixodes Scapularis (Acari: Ixodidae) Exposure Risk Due To Climate Change, Brittany Schappach

Electronic Theses and Dissertations

Increased temperature variances are being recorded in Maine due to climate change, contributing to increased densities of blacklegged ticks (Ixodes scapularis) and concomitant increase in reported cases of tickborne diseases across the state. Understanding the interactions between mean temperature and temperature variance in relation to overwinter tick survival is crucial in understanding the tick’s geographical expansion limits to create better prediction models for their expansion. The goals of this study were to determine the interacting microclimate effects of winter temperature variance and mean temperatures on tick mortality, which month nymphal blacklegged ticks experience highest mortality, and assess the connection between …

Understanding The Contribution Of Gα To The Yeast Pheromone Response, Cory Johnson

Electronic Theses and Dissertations

G-protein coupled receptors (GPCRs) are the target of approximately 35% of all FDA-approved pharmaceuticals. This is because GPCRs regulate different cellular signals including control of cell polarity. The yeast, Saccharomyces cerevisiae, use a GPCR for mating which induces chemotropic growth and morphogenesis toward a mate. In mammalian cells, signaling downstream of the receptor is primarily conducted by the Gα subunit of the large G-protein. In the yeast pheromone response little is known about Gα’s contribution to signaling and the Gβγ subunit is the primary known contributor. This begs the question, what is the contribution of Gα to the yeast pheromone …

Mitochondria Mediated Outcomes Of Developmental Exposure To Low-Level Chemical Mixtures In Zebrafish Danio Rerio, Remy Babich

Electronic Theses and Dissertations

Exposure to drinking water contaminants has been linked to developmental outcomes in both epidemiological and model organism studies. However, low level mixture effects, on early development has yet to be explored. It is hypothesized that early chemical exposures may increase disease susceptibility later in life. This work aimed to investigate impacts of a variety of chemicals and concentrated on metals arsenic (As), cadmium (Cd), vanadium (V), and lead (Pb) due to their presence in drinking water and known developmental toxicity. To determine the effects of a metal and organic contaminant co-exposure, the ubiquitously used herbicide glyphosate was also explored. The …

Quantifying Spatial Heterogeneity Of Wild Blueberries And Crop Water Stress Monitoring Using Remote Sensing Technologies, Kallol Barai

Electronic Theses and Dissertations

The wild blueberry is one of the major crops of Maine, with significant economic value and potential health benefits. Due to global climate change, drought impacts have been increasing significantly in recent years in the northeast region of the USA, causing significant economic losses in the agricultural sectors. It has been predicted to increase further in the future. Changing patterns of the elevated atmospheric temperatures, increased rainfall variabilities, and more frequent drought events have made the wild blueberry industry of Maine vulnerable, suggesting the adoption of novel approaches to mitigate the negative impacts of global climate changes. Also, wild blueberry …

Prevention Of Inflammatory Bowel Disease By Broccoli-Sourced And Microbially-Produced Bioactives, Johanna M. Holman

Electronic Theses and Dissertations

Inflammatory Bowel Diseases (IBD) are chronic, reoccurring, and debilitating conditions characterized by inflammation in the gastrointestinal tract, some of which can lead to more systemic complications and can include autoimmune dysfunction, a change in the taxonomic and functional structure of microbial communities in the gut, and complicated burdens in a person’s daily life. Like many diseases based in chronic inflammation, research on IBD has pointed towards a multifactorial origin involving factors of the host’s lifestyle, immune system, associated microbial communities, and environmental conditions. Too often, research focuses on just one aspect of IBD or uses one model with a narrow …

Developing And Characterizing A Novel Tempo Cnf Hydrogel Adjuvant And Delivery System For Aquatic Vaccines, Kora Kukk

Electronic Theses and Dissertations

Aquaculture is a large part of the food production sector which is greatly expanding. One of the largest losses in aquaculture is due to pathogens. Current solutions for protecting farmed finfish from pathogens can be very expensive with variable efficiency. Current disease prevention strategies include vaccination. Types of vaccines include immersion vaccines, feed vaccines, and injectable vaccines. The most popular solution is oil-based injectable vaccines due to its protection. However, the oil-based adjuvant used in most of these formulations causes adverse reactions in the fish including reduced growth. These vaccines require multiple administrations throughout the fish’s lifetime causing unwanted handling …

Remotely Sensed Assessment Of The Preferred Habitat Of Alexandrium Catenella In The Gulf Of Maine And The Bay Of Fundy, Andre F. Bucci

Electronic Theses and Dissertations

Harmful Algal Blooms (HABs) of the toxic dinoflagellate Alexandrium catenella are an annually recurring problem in the Gulf of Maine (GoM), resulting in risks to human health and substantial economic losses due to shellfish harvesting closures. The monitoring approaches in the region are restricted to real-time identification of the HABs events, when they are clearly underway and already causing deleterious effects to the environment. To fully function as an early warning system rather than an immediate response, monitoring strategies need to be focused on environmental conditions preceding A. catenella HABs. However, the current understanding of the preferred habitat for A. …