Master of Science, The Ohio State University, 2011, Evolution, Ecology and Organismal Biology

Lipids of the stratum corneum (SC), the outer layer of the epidermis of birds and mammals, provide a barrier to water vapor diffusion through the skin. The SC of birds consists of flat dead cells, called corneocytes, and two lipid compartments: an intercellular matrix and a monolayer of covalently bound lipids (CBL) attached to the outer surface of corneocytes. We previously found two classes of sphingolipids, ceramides and cerebrosides, covalently bound to corneocytes in the SC of house sparrows and that these were associated with cutaneous water loss (CWL). In this study, we collected adult and nestling house sparrows from Ohio and nestlings from Saudi Arabia, acclimated them to either a high or low humidity environment, and measured their rates of CWL. We also collected natural populations of nestlings from Ohio and Saudi Arabia from 2 days after hatching until they fledged, and measured their CWL rates. We then evaluated the composition of the CBL of the SC using thin layer chromatography. We found that CBL development differed between habitats, but that lipid density generally increased with age. CBL profile did not exhibit phenotypic plasticity with acclimation and was mostly the same between habitats. CWL appears to be functionally related with the interactions of CBL classes as a whole, and this may be associated with age. Finally, we found that house sparrows have a very diverse range of CBLs in their SC, including free fatty acids and cholesteryl esters, and we propose a new model for CBL organization.

Committee: Joseph Williams (Committee Chair); David Denlinger (Committee Member); W. Mitch Masters (Committee Member) Subjects: Biology; Ecology; Physiology; Zoology

Master of Arts, The Ohio State University, 1922, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1970, Graduate School

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Master of Science, The Ohio State University, 2006, Graduate School

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Master of Science, The Ohio State University, 2007, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1964, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1964, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1950, Graduate School

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Master of Science, The Ohio State University, 2005, Graduate School

Committee: Not Provided (Other) Subjects:

Doctor of Philosophy, Case Western Reserve University, 2024, Molecular Medicine

Cholesterol equilibrium is meticulously orchestrated, and its proper regulation is pivotal in mitigating the risk of cardiovascular disorders. To preserve this delicate balance, cholesterol must activate sensing mechanisms at organelle membranes within the cell's interior. The recently discovered Aster protein family (Aster-A, -B, and -C) partakes in nonvesicular cholesterol import to organelles from the plasma membrane (PM). Despite their high coding sequence homology, each Aster protein exhibits distinct tissue expression patterns, conferring unique functions. This work elucidates their nuanced roles in regulating whole-body cholesterol flux. It scrutinizes how existing therapeutics modulate cholesterol flux, emphasizing their effects on key proteins that are known regulators of cholesterol homeostasis. The introductory chapter reviews the intended and off-target effects of these existing therapeutics. Aster proteins are then introduced as novel modulatory nodes in cholesterol regulation. Aster-C, prominently expressed in sterol- regulatory tissues like the liver and testis, presents an intriguing target, especially in potential therapeutic applications for dyslipidemia-associated disease pathology. The body chapter delves into Aster-C's role in whole-body homeostasis, unveiling its contribution to cholesterol balance and revealing modest effects on bile acid metabolism under low- cholesterol dietary conditions. Aster-C knockout prompts upregulation in the messenger ribonucleic acid (mRNA) levels of paralogs Aster-A and -B in murine liver tissue, suggesting nuanced roles and potential redundancy with other Aster proteins. Comparative nalysis with existing literature indicates that Aster-C's hepatic transcription is inducible by FXR stimulation. These findings, intersected with our own research on the Aster-C knockout-induced disruption of bile acid homeostasis, suggest an integral role for Aster-C in mediating the rate of reverse cholesterol t (open full item for complete abstract)

Committee: Jonathan Mark Brown (Advisor); Christopher Hine (Committee Chair); Scott Cameron (Committee Member); Phillip Ahern (Committee Member); Jonathan Smith (Committee Member) Subjects: Biology; Medicine; Molecular Biology

PHD, Kent State University, 2023, College of Arts and Sciences / Department of Biological Sciences

Anionic signaling lipids (ASL) play multiple crucial roles in the cell. They perform their signaling functions by interacting with (macro)molecules in their vicinity. The headgroups of ASL possess unique physicochemical properties (ionization, hydrogen bond formation, hydration, etc.) that mediate specific interactions in the cell. The physicochemical properties of ASL are modulated based on the characteristics of lipids that surround the ASL as well as changes to conditions in the cytosol. To understand the functions of ASL in the cell, it is first vital to determine their inherent behavior under normal physiological conditions as well as changes to cytoplasmic and membrane properties that occur during signaling and in diseases. In this study, 31P Nuclear Magnetic Resonance was primarily used to investigate the biophysical properties of some ASLs and their interactions with important molecules in the cell that have been overlooked so far. The interactions of phosphatidic acid (PA) with methylated phosphatidylethanolamine (PE) derivatives, increasing cholesterol concentrations, and with the secondary signaling lipid diacyl glycerol pyrophosphate (DGPP) were investigated. We also looked into the interactions of DGPP with cationic molecules. Additionally, we investigated the ionization properties of the 3 monophosphoinositides (PIxP) namely phosphatidylinositol 3-phosphate, phosphatidylinositol 4-phosphate and phosphatidylinositol 5-phosphate in phosphatidylcholine (PC) and in equal concentrations of PC and PE model membranes. For PA, we find that the presence and the number of methyl groups on the methylated PE derivatives differentially affect its ionization properties. Higher levels of cholesterol impact the properties of the membrane to affect the chemical shift of PA, but similar higher cholesterol levels, surprisingly, do not induce significant changes in the pKa2 of PA. The ionization properties of PA and DGPP are both increased when the two lipids are present (open full item for complete abstract)

Committee: Edgar Eduard Kooijman PhD (Advisor); Thorsten-Lars Schmidt PhD (Committee Chair); Manabu Kurokawa PhD (Committee Member); Gary Koski PhD (Committee Member); Elizabeth Mann PhD (Committee Member) Subjects: Biochemistry; Biophysics

Bachelor of Science, Marietta College, 2023, Chemistry

Parabens are commonly used as preservatives in regularly used topical products, but their safety is under discussion since small amounts of paraben have been found in tumor tissue. Mononitroparaben causes cell death in melanoma cells with an LC50 value of 7.02mM after twelve hours of treatment. This study focused on how mononitroparaben affects the cellular lipid content during induced cell death. The experiment was conducted by growing the M624 melanoma cells, dissolving the paraben in methanol, and then leaving 0 mM, 5 mM, and 10 mM concentrations of paraben on the melanoma cancer cells for twelve hours. The paraben was then removed from the cells, and the cells were lysed. Colorimetric cholesterol assays and ceramide assays were completed to determine the changes in cellular cholesterol and ceramide content and the role of cellular lipids in cell death signaling. The results showed that cholesterol concentrations did not significantly change among cells treated with mononitroparaben. However, ceramide significantly increased for cells treated with 10 mM mononitroparaben, which indicated that apoptosis occurred.

Committee: Suzanne Parsons Ph.D. (Advisor); Adam Jacoby Ph.D. (Committee Member); Rakibul Sarker Ph.D. (Committee Member) Subjects: Biochemistry

Doctor of Philosophy (PhD), Ohio University, 2021, Chemical Engineering (Engineering and Technology)

With increasing industrial and biomedical applications of engineered nanomaterials (ENMs), concerns have been raised regarding increased risk of exposure. Exposure to ENMs can potentially lead to adverse health effects including cell toxicity. The plasma membrane, a lipid-protein bilayer surrounding all cells, is the first cellular entity that comes into direct contact with foreign particles. Membrane damage by ENMs is one of the potential mechanisms through which ENMs induce cytotoxicity. In recent years, significant effort has been focused on elucidating the complex interactions at the particle-plasma membrane interface. Such studies have primarily relied on membrane models to tease out what particle physicochemical properties might perturb the structure and function of the cell plasma membrane. However, the role of membrane lipid asymmetry, the fact that the plasma membrane has a different lipid composition in the exofacial leaflet compared to the cytofacial leaflet, in regulating nanoparticle-membrane interactions has remained obscure. In the first aim of this dissertation research, the role of individual membrane leaflets in regulating the interactions of membrane models and erythrocytes with engineered silica nanoparticles (50 and 100 nm) was examined. It was found that silica nanoparticles bind to and disrupt synthetic vesicles mimicking the exofacial leaflet but not those mimicking the cytofacial leaflet of the erythrocyte plasma membrane. Nanoparticles that disrupted vesicles mimicking the exofacial leaflet also induced hemolysis in erythrocytes, suggesting that the exofacial leaflet is the primary regulator of nanoparticle-induced membrane damage. This was confirmed by demonstrating that nanoparticles caused similar disruptive behavior in symmetric and asymmetric vesicles, which had similar outer leaflet, but different inner leaflet lipid compositions. Together, these studies reveal that membrane lipid asymmetry plays a minor role in nanoparticle-induced m (open full item for complete abstract)

Committee: Monica Burdick Ph.D. (Advisor); Amir Farnoud Ph.D. (Committee Member) Subjects: Chemical Engineering; Nanoscience

Doctor of Philosophy, The Ohio State University, 2020, Ohio State University Nutrition

Dietary vitamin A can be obtained in two forms: provitamin A carotenoids (β-carotene, α-carotene, and β-cryptoxanthin) and preformed vitamin A, which exists as retinyl esters (RE) and retinol. β-Carotene can be enzymatically cleaved at the central 15, 15′ bond to give two molecules of retinal. In addition, this carotenoid can undergo oxidative cleavage at bonds other than the central 15, 15′ bond to yield retinoid-like compounds called β-apocarotenoids. Published evidence from our laboratory show that these cleavage products are antagonists of α, β, and γ isoforms of retinoic acid receptors. β-Apocarotenoids have been identified and quantified in fruits and vegetables such as cantaloupes, sweet potatoes, and cassavas biofortified with β-carotene. However, little is known about the intestinal absorption of β-apocarotenoids. It is well established that the liver is the major organ responsible for the uptake, storage, and mobilization of retinoids. Preformed vitamin A, consumed from the diet, is processed into REs during intestinal absorption and packaged into chylomicrons. After remodeling, chylomicron remnant REs are taken up by hepatocytes, hydrolyzed to unesterified retinol, and are either transported to peripheral tissues to meet their retinoid needs or transferred to hepatic stellate cells for re-esterification and storage. Thus, hydrolysis of REs in the liver is important for the maintenance of vitamin A homeostasis but the retinyl ester hydrolase (REH) involved in this process is yet to be established. Evidence from in vitro studies suggest that the enzyme is carboxylesterase Ces1d (ES-10) but this has not been confirmed in studies using animal models. In the first study, we examined the uptake and metabolism of β-apocarotenoids in Caco-2 human intestinal cells. Caco-2 cells were grown on six-well plastic plates until a differentiated cell monolayer was achieved. β-Apocarotenoids were prepared in Tween 40 micelles, delivered to differentiated cells in se (open full item for complete abstract)

Committee: Earl Harrison (Advisor); Martha Belury (Committee Member); Alejandro Relling (Committee Member); Rachel Kopec (Committee Member); Robert Curley Jr. (Committee Member) Subjects: Biochemistry; Nutrition

Master of Science (MS), Ohio University, 2020, Biomedical Engineering (Engineering and Technology)

There is a growing interest in the scientific research community to develop nanoparticles for use in novel commercial and biomedical applications, fueled by recent advances in nanotechnology and nanoparticle synthesis. Potential applications for nanoparticles include use as catalysts during chemical manufacturing processes, use as drug delivery vehicles and imaging agents for biomedical applications, and as surfaces for adsorption during removal of environmental pollutants. The use of nanoparticles in such applications has raised questions concerning their safety and impact on human health. Answers to these questions require a greater understanding of the interactions between nanoparticles and living cells. Models of the cell membrane have been employed to investigate how nanoparticles may adsorb to, fuse with, or penetrate the cell membrane, however careful consideration of the membrane model for such mechanistic studies is necessary. This thesis investigates the role of membrane lipid domains, which are lipid phase segregations comprised of saturated lipids and sterols, in modulating nanoparticle-membrane interactions and further explores how sterol chemistry impacts said interaction. Model membranes were synthesized with an equimolar ratio of sphingomyelin, 1,2-dioleoyl-sn-glycero-3-phosphocholine, and varied sterol composition to yield vesicles with varied lipid domain properties. Fluorescence anisotropy and Forster resonance energy transfer of fluorescent probes was measured to quantify the degree of ordered domain formation in model vesicles. Additionally, confocal microscopy was performed to visualize lipid domains. Following lipid domain characterization, vesicles in which a self-quenching fluorescent dye was encapsulated were exposed to plain silica nanoparticles (diameter 37.5 ± 1.8 nm) and leakage of dye was measured to determine the degree of membrane disruption. By analyzing the results of vesicle leakage assays alongside the results from domain charact (open full item for complete abstract)

Committee: Amir Farnoud (Advisor); Douglas Goetz (Committee Member); Sumit Sharma (Committee Member); Shiyong Wu (Committee Member) Subjects: Biomedical Engineering; Biophysics; Engineering; Nanoscience

Master of Science, The Ohio State University, 2020, Food Science and Technology

Curcumin, the bioactive compound found in turmeric, exhibits a wide range of health-promoting properties. However, its application in food and medicine is limited by its poor bioaccessibility. The purpose of this study was to investigate the potential for corn oil oleogels structured with three different concentrations of rice bran wax (RBW) (2%, 6%, and 10% w/w) to serve as a delivery system for curcumin to increase its bioaccessibility compared to an ungelled (0% RBW) control. The physical properties of oleogels were characterized with and without curcumin to assess the impact of curcumin on oleogel physical properties. Various measures, including texture profile analysis (TPA), solid fat content (SFC), polarized light microscopy (PLM), differential scanning calorimetry (DSC), and x-ray diffraction (XRD), were used to characterize the oleogels. Additionally, an in vitro simulated digestion study was used to assess the bioaccessibility of curcumin in oil and oleogel systems. Data analysis revealed no significant differences in polymorphic or thermal properties between oleogels with and without curcumin; however, differences in microstructural properties were documented for oleogels with curcumin. Curcumin did not appear to have any significant impact on SFC of oil or oleogel samples at a given RBW concentration. Oleogel hardness also differed between control and curcumin-containing oleogels at 10% RBW. After in vitro simulated digestion, oleogels prepared with 2%, 6% and 10% RBW all significantly increased the concentration of curcumin in the micellar fraction relative to the ungelled (0% RBW) control. This finding demonstrates that oleogels structured by RBW effectively increased curcumin bioaccessibility in a simulated digestion model. Results from this study provide insight into the potential utilization of RBW oleogels for delivering curcumin and other poorly water-soluble compounds in food, dietary supplement, pharmaceutical, and cosmetic industries.

Committee: Farnaz Maleky PhD (Advisor); Christopher Simons PhD (Committee Member); Martha Belury PhD (Committee Member) Subjects: Food Science; Nutrition

MS, University of Cincinnati, 2020, Medicine: Biomedical Research Technology

Hematopoietic Stem Cells (HSC) are found in the bone marrow niche of the human body. HSC are the only cells that have both multi-lineage differentiation and self-renewal potential. Maintenance of a healthy HSC pool is crucial for a successful stem cell transplant, which represents a curative therapy for the treatment of hematological disorders. It is well known that with age HSCs lose their ability to differentiate into the various blood lineages. Previous data from our lab has shown that HSCs from the aged animals or after bone marrow transplantation exhibit an altered mitochondrial morphology. The objective of this project is to understand the mechanism of aging of the HSCs and to reverse this effect in order to improve HSC regeneration. Our results show that mitochondrial morphology and its membrane potential are necessary to maintain the differentiation capability of the HSCs. Old HSC have reduced cardiolipin content, a lipid important for mitochondrial functions. Finally, lipid supplementation improves the mitochondrial membrane potential and improves mitochondrial morphology. Together, these findings suggest that lipid supplements may improve HSC functions, which could be used during bone marrow transplantation to promote HSC regenerative potential.

Committee: Rashmi Hegde Ph.D. (Committee Chair); Marie-Dominique Filippi Ph.D. (Committee Member); Damien Reynaud (Committee Member) Subjects: Aging

Doctor of Philosophy (PhD), Ohio University, 2019, Biological Sciences (Arts and Sciences)

The Antarctic notothenioid fishes are among the most stenothermal animals on the planet and are likely to be vulnerable to the effects of global climate change. The physiological mechanisms that govern the thermal tolerance of Antarctic notothenioids are not fully understood. Membrane integrity and structure are highly sensitive to temperature and are critical to maintenance of cellular function. The two central hypotheses of this work are: (1) Variation in physical and biochemical membrane properties exists among notothenioids that display differences in thermal tolerance and thermal sensitivity of physiological processes; and (2) Membranes of Notothenia coriiceps undergo lipid remodeling in response to long-term thermal change in order to conserve membrane properties. Physical and biochemical properties of biological membranes from several tissues (cardiac ventricles and brain) were analyzed in several species of notothenioids in order to characterize variation in properties of biological membranes within this suborder of fishes. I also sought to determine whether notothenioids possess the capacity for acclimation to elevated temperature by determining the extent of compensation of membrane properties in several tissues (cardiac ventricles, brain, gill). Findings from this work provide novel insight into how notothenioids are likely to fare within a warmer climate. An interspecific comparative analysis was performed between notothenioids that exhibit variation in thermal tolerance (Chapters 2, 3). Membrane fluidity and composition were measured in several brain (synaptic, myelin, mitochondria) and cardiac (mitochondria) membranes from the red blooded (more thermotolerant) Notothenia coriiceps and the white-blooded Chaenocephalus aceratus. Synaptic membranes and cardiac mitochondria were more fluid in the icefish, compared to the red-blooded species. Hyperfluidization of membranes, particularly in the less thermotolerant species, C. aceratus, is consistent with the (open full item for complete abstract)

Committee: Elizabeth L. Crockett Ph.D. (Advisor); Janet Duerr Ph.D. (Committee Member); Daewoo Lee Ph.D. (Committee Member); Sarah Wyatt Ph.D. (Committee Member); Theresa Grove Ph.D. (Committee Member) Subjects: Animal Sciences; Aquatic Sciences; Biology; Physiology

Master of Science, The Ohio State University, 2018, Food Science and Technology

The milk fat globule membrane (MFGM) plays an essential role in emulsifying milk fat. In recent decades, the behavior of MFGM polar lipids has been studied using Langmuir trough model systems, were the surface tension of lipid monolayers spread on the surface of a aqueous solution is analyzed as the surface is compressed or expanded. The problem with most Langmuir trough experiments reported in the literature that study MFGM lipid behavior is that they spread MFGM lipids on solutions that are not fully representative of milk. Pure milk naturally contains protein and lipid surfactants, which makes studying the behavior of isolated lipid monolayers spread on pure milk difficult. In this thesis, a process to produce non-surface-active (NSA) solutions from bovine skim milk and dairy-based beverages that have insignificant amounts of surfactants is described. The resulting NSA solutions from the process described here can be used to improve Langmuir trough experiments on MFGM lipids. The process to produce NSA solutions involves two steps. The first step is ultrafiltration of milk through an ultrafiltration membrane with a molecular weight cut-off of at least 10 kDa. The second step is washing the permeate obtained from ultrafiltration 4 times with water-immiscible solvents at a 10:1 permeate to solvent (v/v) ratio. Collected permeate is washed once with hexane, once with chloroform, and then twice with hexane before being filtered through activated carbon. Solvent washing removes proteins in the permeate by forming protein stabilized permeate-in-solvent emulsions that can be separated from the permeate in a separatory funnel. NSA solutions produced from skim milk had a significantly higher surface tension than pure skim milk, resulting from the loss of surfactants. There was no significant difference in the surface tension of the resulting NSA solutions when their surface was compressed, indicating a lack of adsorbed surfactants at their surface. Percent total solids we (open full item for complete abstract)

Committee: Rafael Jimenez-Flores (Advisor); Heather Allen (Committee Member); Emmanuel Hatzakis (Committee Member) Subjects: Food Science

PHD, Kent State University, 2018, College of Arts and Sciences / Department of Biological Sciences

Plants are versatile and diverse photosynthetic eukaryotes. They adapt and flourish in every corner of the earth. Plants have been a vital part of human existence due to their autotrophic ability and therefore abundance. Farming and agricultural advancements have enabled us to use plants as a reliable source of food to meet the continuously increasing food demand. However, crop yield has been affected by the overexploitation of irrigation, misuse of fertilizers and drastic environmental changes. Drought and salinity are among the major causes for loss in crop yield in arid and semiarid parts of the world. In order to meet the demands of a stable food supply we need to find ways to increase crop yield under these severe conditions. Plants overcome environmental stress both biotic and abiotic by modulating their biochemistry. Many of these adaptations are membrane-dependent and mediated via signaling lipids. To understand how plants cope and overcome such stresses we need to take a closer look at its root membrane structure. Biological membranes function as physical barriers that keep the internal and external environment separate and selectively allow transport across this barrier. This makes membranes the first line of defense to all environmental and biological cues. Salinity and draught first affect the plant roots. Membranes i.e. lipid bilayers play a major role in protecting plants by modulating its structure and composition under stress conditions. These stress-signaling events, which help plants to cope with drastic changes, involve the interplay of various proteins and signaling lipids. This dissertation will focus on two such signaling lipids, phosphatidic acid and diacylglycerol pyrophosphate and their interplay with specific target proteins. The work described here brings us closer to understanding the modulations that occur in membrane structure and composition upon stress and how these play a role in salt stress signaling.

Committee: Edgar Kooijman (Advisor) Subjects: Biochemistry; Biology; Cellular Biology; Molecular Biology