50107 research outputs found
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The Coordinated Role of Divalent Cations and Ion Channels in Mouse Oocyte Maturation and Fertilization
No full textFertilization or parthenogenesis of an egg initiates calcium (Ca2+) release, which ultimately triggers egg activation. However, the frequency and duration of this release vary by species. In mice, Ca2+ is released approximately every 10 to 20 minutes for several hours from one of the egg's internal stores, the endoplasmic reticulum. This transient and robust pattern of Ca2+ release is more commonly known as oscillations. The egg/zygote relies on plasma membrane (PM) channels to facilitate the influx of divalent cations from the extracellular environment to maintain these oscillations. Notably, these channels are not only crucial in egg activation but also during oocyte maturation, where an immature oocyte undergoes meiotic restructuring to become a fertilization-competent egg. Mouse oocytes and eggs have three known PM channels: two belong to the transient receptor family, TRPV3 (vanilloid subfamily) and TRPM7 (melastatin subfamily), while the third, Cav3.2, is a low-voltage-gated T-type channel. While these channels have been identified, their overall contributions during oocyte maturation and egg activation remain unclear. Here, we investigate TRPV3's role during oocyte maturation as it gains functionality. We explore how reducing agents impact divalent cation influx and assess the effects of TRPV3 inhibition using channel-specific inhibitors during oocyte maturation and fertilization. Using electrophysiological and microfluorometry techniques, we demonstrate that TRPV3 is a zinc-permeating channel, that DTT potentiates this channel's function, and identify trpvicin as a potent TRPV3 inhibitor in murine oocytes despite limitations.NIH; R01 HD092499 and R21 HD110734 (RAF), R01 HD113358 and R35 GM142537 (AZB), ANID FONDECYT regular 1221308 (IC).Doctor of Philosophy (Ph.D.)2026-09-0
Advancing Objective Assessment of Physical and Behavioral Phenotypes Using Wearable and Mobile Technologies
No full textNeurological disorders and brain injuries often cause physical and behavioral impairments that limit patients' ability to perform daily activities and maintain social connections. Traditional methods for assessing these impairments often rely on subjective clinical measures, which are constrained by the experience of individual assessors. Although patient-reported outcomes provide a more accessible alternative, they are prone to recall bias and personal interpretation, which can compromise the reliability of the evaluations.
To overcome these limitations, mobile and wearable technologies have been widely used for objective, continuous, and scalable monitoring of patients in real-world environments. This dissertation advances the use of mobile and wearable sensing systems to assess behavioral and physical phenotypes in individuals with neurological conditions.
This dissertation first presents the use of mobile devices to predict social isolation in stroke survivors. Ecological momentary assessment surveys were deployed on smart devices to capture real-time behavioral data in daily life contexts. Language embeddings were derived from survey responses to extract rich semantic information.
While mobile devices offer a scalable platform for behavioral assessment, their use can be burdensome in everyday settings. In contrast, wearable devices offer a more passive and continuous monitoring approach, making them well-suited for long-term assessment. Based on this, we examined the use of wearable technology to analyze physical phenotypes in individuals with Parkinson's disease (PD). Leveraging these promising preliminary findings, we refined and validated data analysis techniques to differentiate involuntary upper-limb movements in individuals with Huntington’s disease and PD. Finally, we evaluated the reliability and concurrent validity of two movement segmentation approaches for quantifying upper-limb motor function in stroke survivors. This work ultimately aims to support the development of scalable digital biomarkers that can capture both behavioral and physical impairments in naturalistic settings, enabling more responsive and personalized care for individuals with neurological conditions.Doctor of Philosophy (Ph.D.)2026-09-0
Enforcement of Street Vending Regulations in New York City: How Neighborhood Demographic and Economic Characteristics Shape Patterns of Enforcement
No full textStreet vending is a vital form of informal activity in New York City, sustaining over 23,000 vendors, majority of whom are immigrants and people of color. Despite its economic and cultural importance, street vending is subject to complex, uneven, and often punitive. This thesis investigates how neighborhood economic and demographic characteristics shape enforcement of street vending regulations in Manhattan and Queens, with a particular focus on the influence of privatized governance through Business Improvement Districts (BIDs). Using administrative data on vendor violations from 2020 to 2024, combined with neighborhood socioeconomic data, this study employs negative binomial regression models to analyze patterns of enforcement. Results show that enforcement intensity does not correlate with the density of vendors but is explained by neighborhood property values and the presence of BIDs. Higher population of Hispanic and Asian populations in neighborhoods are associated with somewhat increased enforcement. Building on these findings and informed by theories of urban informality, this thesis recommends inclusive, participatory planning approaches that balance vendor livelihoods with the interests of local businesses and communities. This research contributes to the understanding of informal urbanism in New York City and examines the influence of business and capital interests in enforcement of vending regulation.NoneMaster of Regional Planning (MRP
A volume electron microscopic reconstruction of neurons in the rhinophore ganglion of a nudibranch
No full textUnderstanding how neural circuits are organized is crucial to understanding how animal behavior is generated. Previous volume electron microscopy (vEM) studies in model organisms such as D. melanogaster and C. elegans have provided structural maps for understanding how information is transmitted throughout the nervous system. Here, we applied volume electron microscopy (vEM) to reconstruct neurons and determine synaptic connectivity within the rhinophore ganglion (rhg) of the nudibranch mollusc Berghia stephanieae. The rhg sits at the base of the rhinophores, an olfactory organ, and is presumptively involved in olfactory processing. From our volume EM dataset, we identified a neuropil region containing two neuronal cell types: projection neurons with axons projecting out of the ganglion and afferent neurons originating from the rhinophore nerves. The projection neurons were found to have overlapping dendrites that were contacted by the afferent neurons. Synaptic connections between the projection neurons and the afferents were identified and characterized into four types: monadic, dyadic, polyadic, and convergent. A convergent motif between the projection neurons and afferents was observed. Notably, axo-axonic synapses between afferent neurons was also identified. Convergent input onto projection neurons is a characteristic feature of olfactory glomeruli seen in insects and vertebrates. The presence of olfactory glomeruli in molluscs has been controversial. If this glomerular motif is repeated within the rhg, it would suggest that olfactory glomerular organization evolved independently in molluscs, arthropods, and vertebrates.Master of Science (M.S.
MECHANISTIC ENHANCEMENT OF BACTERICIDAL EFFECTS ON MYCOBACTERIUM ABSCESSUS BY NANOSPONGE DELIVERY OF ANTIMICROBIALS
No full textThe increasing prevalence of bacterial infections has made it crucial to discover novel methods of treatment, especially as resistance to conventional antibiotics also trend to increase. Mycobacterium abscessus is a prevalent pathogen that is intrinsically drug resistant, making it difficult to treat. The use of phytochemicals as an alternative treatment has been explored, but poor solubility in aqueous environments proves it difficult to deliver to mycobacterial biofilms. However, aromatic compounds also prove to be able to induce stress on the membrane, potentially leading to cell death. As well, local hypoxic environments created during infection make it difficult for antibiotics to efficiently reach drug targets. In this study, I investigated how nanosponge-emulsified phytochemicals induce stress and kill M. smegmatis and M. absceuss biofilm cells more efficiently than phytochemicals alone, and that the teamwork of these phytochemicals and antibiotics are more bactericidal in hypoxic conditions. These findings of this study contribute to the development of new strategies for combating bacterial infections, and demonstrate the mechanisms of the nanosponge-emulsion technology utilized.Master of Science (M.S.
Relations between 24-h movement behaviors, declarative memory, and hippocampal volume in early childhood
No full textThis study aimed to determine if 24-h movement behaviors (sedentary time, physical activity, and sleep), considered independently and together, were associated with declarative memory and hippocampal volume in late early childhood. Observational data were obtained from preschool-aged children (timepoint 1: n = 35 children, 3.9 ± 0.5 years; 6 months later: n = 28 children, 4.5 ± 0.5 years). Movement behaviors were measured with actigraphy. Outcomes were declarative memory and hippocampal subregion volumes. Multilevel models explored movement behaviors independently as absolute values, and with both absolute total activity, 24-h sleep duration, and night sleep efficiency. Movement behaviors were also explored as compositions in linear regression models. In independent models, sleep duration and moderate to vigorous physical activity were positively associated with total and right hippocampal volumes, respectively. When examined together, children meeting sleep recommendations were more likely to have larger total, right and left hemisphere, body, and tail hippocampal volumes. In our sample of preschool children, we observed positive associations between sleep duration and hippocampal volume, independent of age. To improve our understanding of the connections between 24-h behaviors and brain health in early childhood, larger samples that also consider the context and subcomponents of movement behaviors may be warranted.UMass SOAR Fun
Preparation and Characterization of Plant Protein-Mushroom Hybrids: Towards more healthy and sustainable foods
No full textThe environmental damage associated with animal-based meat production such as deforestation, habitat loss, high water consumption, and greenhouse gas emissions has driven interest in plant-based alternatives that are more resource-efficient and environmentally friendly. This shift aims to lessen the impact of animal agriculture and promote sustainable food systems. A promising solution is the development of plant protein-mushroom hybrids, which leverage the nutritional benefits of both ingredients to create a product rich in proteins, vitamins, and minerals. These hybrids not only offer unique textures and flavors from mushrooms but also improve binding and mouthfeel from plant proteins, delivering health benefits like cholesterol reduction and immune support. As consumer demand for sustainable options grows, the potential for innovation in plant protein-mushroom hybrids expands, providing healthier and eco-friendly food choices. This study focuses on developing hybrid potato protein-mushroom products to assess their viability as appealing alternatives to animal-based meat by examining the interactions between these ingredients and optimizing their functional and sensory properties.
Initially, we characterized the individual ingredients—potato protein, oyster mushroom (Pleurotus ostreatus), and shiitake mushroom (Lentinula edodes)—to assess their physicochemical properties and suitability for food product development. These mushroom varieties were selected due to their popularity, high nutritional value, and widespread availability, making them ideal candidates for creating hybrid meat alternatives. Following this, hybrid products with a total solids content of 20% (w/w) were created by combining potato protein at 10% or 15% (w/w) with powdered mushrooms at 10% or 5% (w/w) in aqueous solutions containing 100 mM NaCl. To characterize the ingredients and understand their interactions, a series of analyses were conducted to provide insights into how potato proteins and mushrooms react when combined. These analyses aimed to evaluate their charge characteristics, thermal behavior, texture development, and visual appeal. By examining these factors, we aimed to understand the mechanisms that contribute to the stability and functionality of the protein-mushroom hybrids, helping to optimize their properties for better food product development.Master of Science (M.S.
Mineral-associated organic nitrogen pool size, composition, and accessibility mediated by agricultural management and soil mineralogy
No full textMineral-associated organic matter (MAOM) contains nitrogen (N)—a critical macronutrient that often limits plant and microbial growth in terrestrial systems. However, the size, composition, and accessibility of MAOM-N stocks, as well as their vulnerability to agricultural management practices remains largely unknown. We used a combination of chemical and spectroscopic methods to characterize MAOM-N isolated from 9 paired soils spanning a range of geochemical characteristics and maintained under contrasting management regimes—annual wheat monocropping systems or untilled mixed perennial plant communities. We found that on average, MAOM contained close to two-thirds of total soil N. Approximately 20% of this MAOM-N could be mobilized through sequential extractions that mimic conditions in the rhizosphere. More intensive agricultural management resulted in a 50% decline in MAOM-N stocks, as well as a reduction in MAOM-N molecular diversity. Although clay content was positively correlated with total MAOM-N stocks, it was not associated with the quantity of extractable MAOM-N. Instead, extractable MAOM-N was positively correlated with pedogenic oxide content and extractable metals, and negatively correlated with soil pH. Our work demonstrates that MAOM-N has the potential to supply plants and microbes with a substantial quantity of N. Across all soil types, more intensive agricultural management led to a reduction in MAOMN pool size. Since different geochemical characteristics mediate the size and accessibility of this N pool, it may be helpful to consider these characteristics when developing management recommendations for MAOM-N accrual or utilization of MAOM-N for plant nutrition. Taken together, our findings support a growing understanding of MAOM as a dynamic nutrient source and sink.NSF Award #2103076, Lotta Crabtree Agricultural FundMaster of Science (M.S.)2030-02-0
Muscle Fatigue's Impact on Gait Mechanics and Neuromuscular Control in Individuals with Knee Osteoarthritis
No full textFatigue, defined here as a lack of physical and/or mental energy, is a commonly-reported symptom of osteoarthritis (OA) that may limit physical capacity and contribute to disability. In healthy older adults, muscle fatigue (acute decrement in muscle power) has been proposed as a key contributor to symptoms of fatigue. Knee extensor muscle dysfunction, including lower isometric and isokinetic torques and altered muscle activation patterns, are common with knee osteoarthritis (KOA). Together these changes in neuromuscular function may increase locomotor muscle fatigue in KOA compared to age-matched controls, as a greater percentage of the muscle’s capacity must be used for daily activities such as walking. To date, evidence to explain whether and how muscle fatigue may alter control and coordination of movement in KOA is limited. Our working hypothesis was that KOA-related neuromuscular changes may exacerbate locomotor muscle fatigue (Aim 1) and alter the neuro-mechanical response to muscle fatigue during gait (Aim 2), thereby contributing to mobility declines. To assess and compare the mechanisms for loss of force with a prolonged walk in individuals with KOA we used high density EMG (Aim 3). We collected data on 2 groups of 19 participants (9 male, 10 female): KOA (65-80 years) and older healthy controls (70-80 years). We implemented a 30-minute treadmill walk (30MTW) to induce knee extensor muscle fatigue and quantified the response with measures of gait mechanics, electromyography, physical performance, and motor unit behavior. We found that knee extensor peak power during dynamic contractions is lower in individuals with KOA compared to older healthy, however, muscle fatigue in response to a 30MTW is not different between groups, and intramuscular fat negatively is associated with poorer mobility. We also found that individuals with KOA do not experience greater performance fatigability (6m walk test) than age and sex matched controls, but they do alter gait mechanics and muscle activation in response to a 30MTW. Finally, individuals with KOA do not have impaired force steadiness as compared to older healthy controls and that only the recruitment threshold is impacted by a 30MTW in individuals with or without KOA. The results of this study suggest that individuals with and without KOA experience measurable knee extensor fatigue in response to 30MTW and individuals with KOA adapt to this fatigue with a gait strategy aimed at maintaining joint stability and attenuating load on the knee joint.This dissertation was funded by the following sources: the National Institute of Aging under award numbers F31AG079538 and R01AG068102, an International Society of Biomechanics Matching Dissertation Grant, and a UMass Amherst Graduate School Dissertation Grant.Doctor of Philosophy (Ph.D.
Tunable and Perfusable Vascularized 3D Tissue Mimics to Study Breast Cancer Extravasation
No full textCancer metastasis, the spread of cancer cells to distant organs, is responsible for 90 percent of cancer-related deaths. Cancer cells need to enter and exit circulation in order to form metastases, and the vasculature and endothelial cells are key regulators of this process. While vascularized 3D in vitro systems have been developed, few have been used to study cancer, and many lack key features of vessels that are necessary to study metastasis. This project aims to create a device that can better model tissue-specific cancer cell extravasation in the tunable PEG hydrogel system used in our lab. Ultimately, the purpose of creating this device is to determine the different conditions that can lead to the extravasation of breast cancer cells across the endothelial cell barrier into these different tissue mimics. Here, I demonstrated the development of a vascularized 3D tissue model in vitro in a collagen hydrogel as well as in a synthetic PEG-Maleimide hydrogel that can be easily tuned to the variations in different extracellular matrix stiffness and protein composition that exist in different tissue types. In optimizing this process, I have identified several key factors that aid in creating channels in hydrogels, including device design, subtractive element choice and coating, gel formulation, and endothelial cell seeding density. This system is easily adapted to study and collect data on extravasation as it relates to particular tissue microenvironments for many cancer types.Doctor of Philosophy (Ph.D.