Energetic Limitations Of Thermophilic Methanogens And Thiosulfate Reducers In The Subsurface Biosphere At Deep-Sea Hydrothermal Vents, Lucy C. Stewart

Doctoral Dissertations

This dissertation examined the substrate and energetic limitations of hydrogenotrophic thermophiles from deep-sea hydrothermal vents. Thermophilic and hyperthermophilic organisms in diffuse hydrothermal venting are thought to represent a hot subsurface biosphere associated with deep-sea hydrothermal vents, where primary production is dominated by hydrogenotrophy rather than sulfide oxidation as at the vent/seawater interface of hydrothermal sulfide chimneys. Methanogens and sulfur-reducers are known to compete for hydrogen in mesophilic, freshwater systems, and likely do so in deep-sea hydrothermal vent environments as well. However, the exact size and biomass of the subsurface biosphere is difficult to determine through direct sampling. Firstly, the distribution …

Pro- And Antioxidant Effects Of Phospholipids On Lipid Oxidation In Bulk Oil, Leqi Cui

Doctoral Dissertations

The aim of this thesis is to explore how phospholipids at concentrations similar as in refined vegetable oils impact bulk oil lipid oxidation. The possible formation of association colloids and synergism with primary antioxidants are considered. The results provided a better understanding of the pro- and antioxidant activities of phospholipids. Lipid oxidation leads to quality deterioration by generating off-flavor, nutrient loss, color alteration, texture changes, and even generation of potential toxic products. Phospholipids are important minor components in edible oil that play a role in lipid oxidation. Surface active phospholipids have an intermediate hydrophilic–lipophilic balance value, which allows them to …

Characterization Of The Role Of Intrinsic And Extrinsic Factors During Murine Endoderm Development, Siyeon Rhee

Doctoral Dissertations

Yin Yang1 (YY1) is a ubiquitously expressed factor that plays multiple roles in early mouse development. We have found that an essential role of YY1 in the visceral endoderm (VE) of the yolk sac is the maintenance of VEGF. Furthermore, we have demonstrated that paracrine signals downstream of VEGF support the VE, assessed by maintenance of HNF4α. Because the VE is essential for yolk sac development, and thus for embryonic survival, we used an inducible-knockout strategy to demonstrate that YY1 is essential in the definitive endoderm (DE) for invasion of hepatoblasts into the surrounding mesenchyme. By E14.5 YY1-/- livers are …

New Insights Into The Role Of The Udp-Glucose: Glycoprotein Glucosyltransferase 1 In The Endoplasmic Reticulum Quality Control, Abla Tannous

Doctoral Dissertations

The UDP-glucose:glycoprotein glucosyltransferase 1 (UGT1) is a central quality control factor in the Endoplasmic Reticulum (ER). It surveys the folding status of proteins in the ER and redirects them, via its reglucosylation activity, to bind to the ER carbohydrate binding (lectin) chaperones calreticulin (CRT) and calnexin (CNX). However, the cellular mechanism of UGT1 is not completely understood. Using a cell based reglucosylation assay, we found that UGT1 reglucosylated proteins that eventually fold. This modification was transient and resulted in delay of protein trafficking in the secretory pathway and prolonged binding to lectin chaperones in the ER. In addition, terminally misfolded …

Complex Effects Of Ungulate Browsers On Tree Recruitment And Herbaceous Layers In New England Temperate Forests, Edward K. Faison

Doctoral Dissertations

Browsing by ungulates is a leading biotic disturbance in northern forest ecosystems and an important determinant of habitat, biodiversity, and ecosystem services. A large body of work has revealed that white-tailed deer (Odocoileus virginianus) at high densities alter forest understories in strong and predictable ways; however, less is known about how lower densities of deer and the combined effects of multiple herbivores influence forest understory vegetation, particularly in stands following canopy disturbance. Using fenced exclosures, remote cameras and other field observations, I explored the foraging response and browsing effects of low densities of deer and moose (Alces …

Role Of Lipid-Based Delivery Systems In The Biological Fate Of Lipophilic Nutraceuticals And Inorganic Nano-Particles In The Gastrointestinal Tract, Mingfei Yao

Doctoral Dissertations

The oral bioavailability of lipophilic bioactive molecules can be greatly increased by encapsulating them within engineered lipid nanoparticles, such as micelles, microemulsions and nanoemulsions. After ingestion these engineered lipid nanoparticles are disassembled in the gastrointestinal tract (GIT), and then reassembled into biological lipid nanoparticles (mixed micelles) in the small intestine. These mixed micelles solubilize and transport lipophilic bioactive components to the epithelium cells. The mixed micelles themselves are then disassembled and reassembled into yet another form of biological lipid nanoparticle (chylomicrons, CMs) within the enterocyte cells. The CMs carry the bioactive components into the systemic (blood) circulation via the lymphatic …

Effects Of Conjugated Linoleic Acid (Cla) On Skeletal Muscle Metabolism, Yoo Kim

Doctoral Dissertations

Although it is well known that increased physical activity can help reduce incidences of obesity, physical activity can be influenced by complex issues, making it difficult to use universal means to control obesity. Recent discoveries of the effects of exercise at the cellular level opened up the unique opportunity to develop compounds with ‘exercise-like’ effects. In fact, CLA has been shown to promote voluntary activity and endurance capacity in mice. Thus, the purpose of these studies is to determine the mechanisms of conjugated linoleic acid on muscle metabolism via the modulation of biochemical events including mitochondrial biogenesis and the alternation …

Uncovering New Roles For The Cell Surface Protease Adam13 In Neural Crest Migration, Genevieve Abbruzzese

Doctoral Dissertations

ADAMs are a family of transmembrane metalloproteases that control cell behavior by cleaving both cell adhesion and signaling molecules. They play a variety of roles in diverse tissue types during development and can affect cell processes such as migration, differentiation, growth and survival. In the embryo, several ADAMs have proven to be integral components of the cranial of neural crest (CNC), which is a multipotent population of cells that gives rise to multiple structures of the face and head. These cells are highly motile and undergo a large-scale migration throughout the embryo that is essential for proper craniofacial development. The …

The Investigation Of Rhodiola Crenulata Root Extract Effects On Obesity Associated Inflammation And The Antineoplastic Mechanism In Breast Cancer Cells, Lotfi M. Bassa

Doctoral Dissertations

Obesity and breast cancer are two disease models that directly affect the United States population, as more than 35% of the adult population is obese [8], and more than 200,000 new cases of breast cancer are diagnosed in the United States per year [34]. Several diseases are associated with obesity including, cardiovascular disease, insulin resistance, increased inflammation and increased cancer risk [9,10]. Therefore it essential to understand the risks associated with obesity as well as to investigate possible preventive and/or therapeutic treatment strategies. Rhodiola crenulata is a Tibetan plant that has been used in Eastern traditional medicine to relieve depression, …

Responsive Supramolecular Assemblies Based On Amphiphilic Polymers And Hybrid Materials, Longyu Li

Doctoral Dissertations

The design and synthesis of responsive supramolecular assemblies are of great interest due to their applications in a variety of areas such as drug delivery and sensing. We have developed a facile method to prepare self-crosslinking disulfide-based nanogels derived from an amphiphilic random copolymer containing a hydrophilic oligo-(ethylene glycol)-based side-chain functionality and a hydrophobic pyridyl disulfide functional group. This thesis first provides a concept of studying the influence of Hofmeister ions on the size and guest encapsulation stability of a polymeric nanogel. The size and core density of nanogel can be fine-tuned through the addition of both chaotropes and kosmotropes …

Chemical Biology-Based Probes For The Labeling Of Targets On Live Cells, Amanda M. Hussey

Doctoral Dissertations

Proper detection is the key to studying any processes on the cellular scale. Nowhere is this more evident than in the tight space which confines the synaptic cleft. Being able to ascertain the location of receptors on live neurons is fundamental to our understanding of not only how these receptors interact and move inside the cell but also how neurons function. Most detection methods rely on significantly altering the receptor; both tagging with a fluorescent protein or targeting the receptor by a fluorescent reporter in the form of a small molecule causes significant difficulties. These localization techniques often result in …

Behavioral And Neural Mechanisms Of Impulsive Choice, Jesse Mcclure

Doctoral Dissertations

Impulsive choice is defined as the preference for a small immediate reward over a larger delayed reward. Individual variablity in impulsive choice correlates with many socially relevant behaviors. Although forms of impulsive choice have been studied in both behavioral ecology and psychology, the exchange of knowledge between these fields is just beginning. Drawing from both of these fields will improve our research methods allowing for a more detailed understanding of this complex behavior. Existing tasks to measure impulsive choice conflate the delay and quantity of the reward. To address this, I have drawn from foraging research to establish a method …

Structural Design Approaches For Creation Of Reduced Fat Products, Bicheng Wu

Doctoral Dissertations

In awake of the health issues related with high-calorie diet, there was a strong focus in the development of reduced-fat products in the food industry. However, fat plays an important role in determining the quality attributes of food products such as texture, appearance, flavor and stability, therefore there has been limited success for reduced-fat products. This thesis project thus targeted liquid and semi-solid products such as dressings, sauces, and aimed to address problems associated with low-fat by utilizing structural designed approach. The first part of this project focused on using controlled aggregation of protein-stabilized lipid droplets to regulate the microstructure …

Plant Patents - Presentation To Northfield Garden Club, Paulina Borrego

Paulina Borrego

Plant Patents

Recent Advances In Functional Assays Of Transcriptional Enhancers, Courtney Babbitt, Michele Markstein, Jesse Gray

Michele Markstein

In this special edition of Genomics, we present reviews of the current state of the field in identifying and functionally understanding transcriptional enhancers in cells and developing tissues. Typically several enhancers coordinate the expression of an individual target gene, each controlling that gene's expression in specific cell types at specific times. Until recently, identifying each gene's enhancers had been challenging because enhancers do not occupy prescribed locations relative to their target genes. Recently there have been powerful advances in DNA sequencing and other technologies that make it possible to identify the majority of enhancers in virtually any cell type of …

Molecular Mechanisms Underlying The Contralateral Repeated Bout Effect (Crbe) In Human Skeletal Muscle, Ling Xin

Doctoral Dissertations

Eccentric (muscle lengthening) exercise induces temporary muscle damage that can lead to long-term muscle adaptation, a process known as the repeated bout effect where subsequent exercise results in less damage. The existence of a contralateral repeated bout effect (CRBE) has been controversial. The primary goals of this study were to: 1) validate the existence of the CRBE; and 2) define the underlying molecular mechanisms. Thirty-six young men performed 100 maximal eccentric actions of the knee extensors using one leg (bout 1) and repeated the exercise with the contralateral leg five weeks later (bout 2). Vastus lateralis muscle biopsies were …

Design And Synthesis Of Polymeric Nanoparticles For Drug And Protein Delivery, Judy A. Ventura

Doctoral Dissertations

Nanoparticles are emerging as carriers in biological applications due to advances in their preparation, size control, surface modification and encapsulation capabilities. In addition, nanomaterials improve bioavailability by enhancing aqueous solubility of the guest molecule and increasing resistance time in the body. However, the delivery of guest molecules is still challenging due to the intrinsic characteristics of the guest molecule including large size and propensity to denature or degradation in the case of biomolecules and the encapsulation stability of the small guest molecules. Our group recently reported the preparation of self-cross-linked polymeric nanogels possessing surface functionalization capabilities. In this dissertation we …

Inhibition And Cofactor Targeting Of Hypoxia-Sensing Proteins, Cornelius Y. Taabazuing

Doctoral Dissertations

Hypoxia Inducible Factor (HIF) is a transcription activator considered to be the main regulator of O₂ homeostasis in humans. The transcriptional ability of HIF is regulated by the Fe²⁺/αKG-dependent enzyme, Factor Inhibiting HIF (FIH). FIH uses molecular oxygen to catalyze hydroxylation of an asparagine residue (Asn⁸⁰³) in the C-terminal transactivation domain (CTAD) of the HIFα subunit, abrogating HIF target gene expression. The mechanism of FIH and other αKG-dependent oxygenases involves the ordered sequential binding of αKG, substrate, and O₂, which becomes activated to form a reactive ferryl intermediate that hydroxylates the substrate. The …

The Effectiveness And Applicability Of Amphibians As Indicator Species For Long-Term Monitoring Of Ecological Changes In New England Forests, Ahmed Siddig

Doctoral Dissertations

The objective of this study is to assess the potential of two amphibians species, Eastern Red-backed Salamander (Plethodon cinereus (Green)) and Eastern Red-spotted Newt (Notopthalmus viridescens viridescens Rafinesque), as indicator species of forest disturbances at Harvard Forest, located in Petersham, Massachusetts, United States. Specifically, I 1) assess the impacts of these focal species to decline of hemlock forests in Harvard Forest; 2) calibrate abundance indices of P. cinereus based on artificial and natural objects surveys with a population size estimator based on depletion sampling; and 3) assess the potential of these salamanders as indicator species by developing an …

Engineering Novel Detection And Treatment Strategies For Bacterial Therapy Of Cancer, Jan T. Panteli

Doctoral Dissertations

Finding and treating cancer is difficult due to limited sensitivity and specificity of current detection and treatment strategies. Many chemotherapeutic drugs are small molecules that are limited by diffusion, making it difficult to reach cancer sites requiring high doses that lead to systemic toxicity and off-target effects. Tomographic detection techniques, like PET, MRI and CT, are good at identifying macroscopic lesions in the body but are limited in their ability to detect microscopic lesions. Biomarker detection strategies are extremely sensitive and able to identify ng/ml concentrations of protein, but are poor at discriminating between healthy and disease state levels due …

Evaluation Of Leafy Green Species Popular Among Ethnic Groups For Production And Markets In The Northeastern Usa, Ricardo A. Orellana

Doctoral Dissertations

ABSTRACT

Impact Of A Preschool Workplace Intervention On Classroom Teachers’ Physical Activity Levels And Quality Of Life, Ogechi O. Nwaokelemeh

Doctoral Dissertations

PURPOSE: To examine the feasibility and efficacy of a three-month, cluster-randomized workplace PA intervention on PA levels and wellbeing measures in preschool classroom teachers. METHODS: Ten preschool centers were randomized into two groups; short-bouts of structured PA (SBS-PA, n=5) or traditional unstructured PA (TRAD-PA, n=5). The SBS-PA intervention consisted of 10-minute structured, teacher-led PA routines implemented within the classroom setting, followed by 20 minutes of unstructured playtime. The TRAD-PA intervention consisted of supervised 30-minute of unstructured free playtime. Both interventions were implemented during the morning and afternoon designated gross-motor playtime for 30 min/session, five days/week for three months. Participants’ …

Transferrin-Based Therapeutics And Analytical Methods To Characterize Them, Son N. Nguyen

Doctoral Dissertations

Modern development of medicine requires detailed characterization by state-of-the art analytical techniques that can be used to analyze covalent structure, conformations and protein-receptor interaction to quantitatively measure biodistribution of protein therapeutics. Mass spectrometry has already become an indispensable tool facilitating all stages of protein drug development. Particularly, this work has demonstrated the tremendous potential of electrospray ionization (ESI) mass spectrometry (MS) in this arena by providing invaluable information beyond mass measurement that can be used to optimize protein drug conjugate structures during early stages of development, and to further catalyze drug design efforts. Additionally, a new sensitive and selective method …

Structure-Property Relationships At The Nano-Bio Interface: Engineering The Nanoparticle Surface For Immunomodulation, Daniel Fernando Moyano Marino

Doctoral Dissertations

Each year, a variety of novel nanomaterials are being developed with the objective of treating different diseases. However, since nanomaterials are foreign to the human body, one of the principal factors that limit their use is the encounter with the first line of defense from the body: the immune system. If this interaction is not taken into account, an undesired recognition takes place and the efficiency of nanoparticle based therapies is dramatically reduced. As such, understanding the rules that govern this recognition is of prime importance in the field of nanomedicine. Following this line of thoughts (the driving force), the …

Physicochemical And Toxicological Assessment Of Antimicrobial Ε-Polylysine-Pectin Complexes, Cynthia L. Lopez Pena

Doctoral Dissertations

ε-Polylysine is an appealing FDA-approved, all natural antimicrobial biopolymer effective against a wide range of microorganisms. Its implementation is greatly limited by its strong cationic charge, which has been linked to instability in food systems, perceived astringency and bitterness, and the ability to inhibit lipid digestion. Previous studies have shown that controlled complexation of ε-polylysine with anionic pectin is able to prevent instability and astringency in simplified model food systems, while maintaining the antimicrobial character of polylysine. Isothermal titration calorimetry, micro-electrophoresis, microscopy, and turbidity analyses of the stability of electrostatic pectin-polylysine complexes in the presence of strongly anionic κ-carrageenan, and …

Mimicking The Arterial Microenvironment With Peg-Pc To Investigate The Roles Of Physicochemical Stimuli In Smc Phenotype And Behavior, William G. Herrick

Doctoral Dissertations

The goal of this dissertation was to parse the roles of physical, mechanical and chemical cues in the phenotype plasticity of smooth muscle cells (SMCs) in atherosclerosis. We first developed and characterized a novel synthetic hydrogel with desirable traits for studying mechanotransduction in vitro. This hydrogel, PEG-PC, is a co-polymer of poly(ethylene glycol) and phosphorylcholine with an incredible range of Young’s moduli (~1 kPa - 9 MPa) that enables reproduction of nearly any tissue stiffness, exceptional optical and anti-fouling properties, and support for covalent attachment of extracellular matrix (ECM) proteins. To our knowledge, this combination of mechanical range, low …

Interactions Between The Hypothalamic-Pituitary-Adrenal (Hpa) Axis, Oxytocin System, And Behavior In Differently Reared Rhesus Monkeys (Macaca Mulatta), Amanda F. Hamel

Doctoral Dissertations

Adverse experiences that occur during early critical periods of development modify activity of neuroendocrine systems, such as the hypothalamic-pituitary-adrenal (HPA) axis and oxytocin system. This dissertation examines the effects of nursery rearing, an established model of adverse early experiences, on activity of the HPA axis and oxytocin system in infant and adult rhesus macaques (Macaca mulatta). In addition, influence of oxytocin system activity on the HPA axis and behavioral reactivity was examined. In infant monkeys, nursery-rearing was associated with lower HPA axis, yet higher oxytocin system activity, following the acute stress of developmental assessment. Nursery rearing may result …

Estrogen-Sensitive Learning Is Not Affected By Combination Ethinyl Estradiol And Levonorgestrel Oral Contraceptive Use, Darlene F. Ficco

Doctoral Dissertations

Two studies were conducted to explore the cognitive effects of combination ethinyl estradiol and levonorgestrel contraceptive use during late adolescence and young adulthood. Three groups of females, naturally cycling, active pill phase, and hormone-free interval phase, were tested on a battery of estrogen-sensitive, i.e., place learning and word generation, and estrogen-insensitive, i.e., map drawing, mental rotation, digit span, story recall, and object recall, tasks. Study 2 was conducted as a means to replicate the findings observed in Study 1 and to manipulate task difficulty and sensitivity. Two measures of mood were administered, and salivary estradiol levels at time of testing …

Experimental Test Of Genetic Rescue In Isolated Populations Of Brook Trout, Zachary L. Robinson

Masters Theses

Translocations are an important aspect of the management of natural populations in an increasingly fragmented landscape. Maintaining connectivity and gene flow is beneficial for both contemporary fitness and adaptive potential in the face of environmental change. Genetic rescue (GR) can alleviate inbreeding depression, genetic load, and increase adaptive potential of populations. Here, I have translocated 10 (5 of each sex) brook trout (Salvelinus fontinalis) to four geographically proximate and environmentally similar fragmented stream-dwelling populations of brook trout in Virginia to test for genetic rescue. The translocated brook trout contributed to more families than would be expected under neutral …

The Effects Of Ovarian Hormones And Exercise On Gene Markers Of Cardiac Dysfunction, Anisha S. Patel

Masters Theses

Heart disease is the leading cause of death in women in the United States. Premenopausal women appear to have better cardiac function and lower risk of heart disease compared to male postmenopausal female counterparts. Ovarian hormone loss influences blood pressure homeostasis and causes systemic inflammation, which may result in chronic stress on the heart. Two key physiological changes in cardiac dysfunction are reemergence of the fetal gene pattern and myocardial remodeling. Physical activity has been linked to improved cardiac function. The purpose of this study was to investigate the effects of ovariectomy on early markers of cardiac dysfunction and fibrosis …