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Molecular mechanisms of quorum sensing gene regulation via RhlR in Pseudomonas aeruginosa
No full textPseudomonas aeruginosa (P. aeruginosa), a bacterial pathogen notorious for hospital-borne infection and antibiotic resistance, uses quorum sensing to coordinate pathogenic group behaviors. The quorum sensing transcription factor RhlR is activated by the autoinducer C4-homoserine lactone (C4-HSL) and its activity is modified by a protein-protein interaction with the enzyme PqsE. Under the control of RhlR, azeB is the primary gene responsible for the production of the natural product azabicyclene. Construction of a heterologous Escherichia coli (E. coli) luciferase reporter assay allows for the quantification of azeB promoter activation in response to pqsE mutants with varied RhlR-interacting and catalytic abilities. At moderate C4-HSL concentrations, RhlR-interacting PqsE mutants diminish azeB promoter activation relative to non-interacting mutants. In the absence of C4-HSL this pattern is reversed; RhlR-interacting PqsE mutants instead produce increased azeB promoter activation. This pattern is also observed in a P. aeruginosa azeB reporter assay emphasizing the importance of the PqsE-RhlR interaction as a determinant of azeB promoter activation, and presumably azabicyclene synthesis. PqsE has been shown to adapt the transcription factor activity of RhlR to C4-HSL concentration in a promoter specific manner. These results may be mediated by the formation of high molecular weight RhlR oligomers at high C4-HSL concentrations.ChemistryBachelors of Science (BS
CPTH2-Driven Acetyltransferase Inhibition Impacts Thyroid Hormone Receptor Localization and Acetylation Levels
No full textThyroid hormone plays a critical role in regulating metabolism, growth, and development by binding to the thyroid hormone receptor (TR) and modulating gene expression. Evidence indicates an elaborate system of TR nuclear import and export that extends beyond its role as a transcription factor. TR contains nuclear localization signals (NLSs) and nuclear export signals (NESs) that promote interactions with nuclear transport proteins and subsequent import or export through nuclear pore complexes. The precise mechanisms and reasonings underlying TR nucleocytoplasmic shuttling remain elusive. A working model suggests the involvement of a series of acetylation events catalyzed by lysine acetyltransferases (KATs). However, it remains unclear which particular KATs are involved. Our previous work with C646, a specific inhibitor of the CBP/p300 KAT, points to this enzyme’s involvement in TR nucleocytoplasmic shuttling. To investigate the involvement of other KATs, I utilized CPTH2, a broad-spectrum inhibitor of KATs GCN5, CBP/p300 and, to a lesser degree, PCAF. After transfection with GFP-tagged TRα1, TRβ1, or TRβ2 expression plasmids, CPTH2-inhibited HeLa (human) cells were tested against dimethyl sulfoxide (DMSO) (vehicle)-control cells. Cells were visualized using fluorescence microscopy, and nuclear-to-cytoplasmic fluorescence ratios were calculated and averaged for each treatment group. Since TRα1 is already predominantly localized to the nucleus, the addition of CPTH2 did not detectably affect localization. However, the CPTH2-inhibited TRβ1 and TRβ2 groups showed significantly reduced cytoplasmic localization compared to the DMSO-controls, with p-values of 1.86 × 10-95 and 5.20 × 10-95, respectively. Phalloidin-TRITC staining of actin also revealed improper morphology and decreased cell-cell communication at higher concentrations of CPTH2. This change was not observed in cells treated with C646, implying GCN5 is involved in the maintenance of actin stress fibers. Changes in TR acetylation levels between CPTH2 and DMSO groups were determined by immunoprecipitation. Lysates from HeLa cells transfected with HA-tagged TRα1 were processed with acetyl-lysine affinity beads and analyzed by immunoblotting with anti-HA antibodies. While CPTH2-inhibited cells did show less acetylated TR compared to the DMSO-control on average, results were variable, and the p-value for this experimentation was not significant (0.191). Further localization experimentation compared treatment with CPTH2 versus C646 to specifically investigate whether GCN5 interacts with TR in addition to CBP/p300. HeLa cells transfected with GFP-tagged TRβ1 were treated with CPTH2, C646, or DMSO (vehicle)-control. Statistical analysis between the CPTH2 and C646 treatments yielded a p-value of 0.144, indicating CPTH2 inhibits proper TR localization comparably to C646. TRα1 immunoprecipitation and subsequent detection by α-GCN5 antibody did not reveal any interaction between the two proteins. It remains unclear whether GCN5 is directly implicated in the acetylation of TR and its nucleocytoplasmic shuttling mechanism. While CPTH2 global inhibition superficially points to involvement, C646 comparative analysis and TRα1 co-immunoprecipitation contradict this claim. Regardless, the results of our experimentation further advance our understanding of the acetylation-dependent model of TR shuttling and may highlight potential targets for therapeutic intervention in diseases linked to improper TR localization.BiologyBachelors of Science (BS
Revolutionizing Gender in One Minute or Less: Informally Theorizing Nonbinary Identity on TikTok
No full textThe isolation following the COVID-19 pandemic had a massive influence on where young Americans chose to seek out community and comfort, namely social media platforms such as TikTok. TikTok’s ability to cater to the niche interests of its users made it a digital space that was used throughout the pandemic for teenagers and young adults questioning their gender identity to find each other and attempt to document and discuss their own lived experiences. A shift in how American society conceptualizes gender is both seen in and influenced by the youth discussion of nonbinary identity and its spread in the form of changing pronouns and new modes of gender presentation. I use the lens of informal theorizing to examine how young nonbinary and gender non-conforming Americans are parsing themselves on TikTok, piecing together their identities through humor, abstraction, and communal discussion.American StudiesBachelors of Arts (BA
Mutations and Modifications: The Cellular Fate of Thyroid Hormone Receptors
No full textThyroid hormone receptors (TRs), members of the nuclear receptor super family, are transcription factors responsible for binding thyroid hormone (T3) and activating or repressing the expression of target genes to regulate metabolism, cell growth, and energy expenditure. Intracellular dynamics of TR, particularly its compartmentalization and mobility within the cell, are known to regulate its transcriptional role. Three TR subtypes, TRa1, TRb1, and TRb2, are abundant differentially in human tissues, with TRa1 observed predominantly in cells of the central nervous system, intestines, bones, and cardiac tissue. Recent characterization of TRa1 involvement in Resistance to Thyroid Hormone Syndrome a (RTHa), a rare genetic disorder, has initiated research efforts to elucidate the underlying mechanism of pathogenesis. Several mutations have been identified in RTHa patients with varying degrees of symptom severity. Among others, missense mutations at alanine 263 have been observed with considerable frequency. A263V and A263S substitutions were identified in several families with the condition, with the valine mutation displaying increased severity in skeletomuscular and neuropsychological development delays. Certain RTHa mutants were previously demonstrated to have increased affinity for Nuclear Corepressor 1 (NCoR1), a coregulator of TRa1, and are proposed to form more stable repressor complexes compared to wild type TRa1. To determine whether NCoR1 promotes nuclear retention of RTHa mutants, in the first portion of this thesis, we cotransfected HeLa cells with expression plasmids for mCherry-TRa1 wild-type or RTHa mutants and GFP-NCoR1. Using fluorescence microscopy, we compared Nuclear-to- Cytoplasmic (N/C) localization ratios of wild-type TRa1 to the A263V and A263S mutants in the presence of NCoR1 and its non-TR-binding counterpart NCoRΔID, as a control. We observed a significant increase in the nuclear retention of A263V and significant decrease for A263S among other mutants with the overexpression of NCoR1 relative to wild-type TRa1. In NCoR1-knockout cells, nuclear retention of A263S and A263V was significantly decreased compared to control (wild-type) cells. Luciferase reporter gene transcription mediated by TRα1 was significantly repressed by NCoR1 overexpression. Most RTHα mutants showed minimal induction regardless of NCoR1 levels, but T3-mediated transcriptional activity was decreased for R384C and F397fs406X when NCoR1 was overexpressed. Our results suggest that the observed deviations in the localization of RTHa mutants relative to wild-type TRa1 may, in part, be caused by changes in the stability of the repressor complex, providing further insight into RTHa pathogenesis on a molecular level. The second portion of this thesis focuses on the post-translational modifications that regulate TR activity. Previous work in the lab using fluorescent tagged acetylation (KàQ) and nonacetylation (KàR) mimic constructs of key lysine residues within nuclear localization signal 1of TRa1 (K130/134/136) and TRb1 (K184/188/190) had shown that acetylation mimics have significantly lowered N/C localization ratios, and nonacetylation mimics had reduced intranuclear mobility correlated with increased nuclear retention. Pharmacological inhibition of sirtuin 1 (SIRT1) by EX527 and HDAC6 by Tubastatin-A (Tub-A) among a panel of lysine deacetylases (KDACs) from all classes showed no significant changes in localization of TRa1, TRb1, and TRb2 due to deacetylase inhibition. Coimmunoprecipitation experiments with anti- HDAC3, anti-HDAC6, and anti-SIRT1 antibodies showed no detectable interaction between TRa1 and HDAC3 or HDAC6, or between TRb1 and SIRT1. The culmination of these efforts did not identify a key deacetylase acting on TR as a substrate. Pilot studies in the lab revealed that acetylated TRa1 had increased susceptibility to proteases in the nucleus. While the ubiquitination sites of TR are unknown, we hypothesized that acetylation state may regulate ubiquitin-mediated degradation of TRa1 through cross-talk. Immunoprecipitation with ubiquitin affinity beads of HeLa cell lysates expressing HA-tagged wild-type TRa1, nonacetylation mimic, and acetylation mimic and subsequent anti-HA chemiluminescent western blot analysis showed that ubiquitination does not directly compete with acetylation at residues K130/134/136, as consistent monoubiquitination was observed in all three treatment groups. The nonacetylation mimic had significantly reduced polyubiquitination compared to the acetylation mimic, whereas the acetylation mimic had significantly elevated polyubiquitination in the first 3 out of 4 discreet polyubiquitinated states observed compared to wild-type. Results suggest that wild-type TRa1, which exists as a nonhomogeneous combination of the acetylated and nonacetylated populations within the cell, mostly remains in the nonacetylated state, and the acetylation of residues K130/134/136 prompts subsequent polyubiquitination which, consistent with pilot data, may target the receptor for ubiquitin mediated proteasomal degradation at the end of its life cycle.BiologyBachelors of Science (BS
Feature Extraction of Photoplethysmography Waveforms for the Development of Machine Learning Based Blood Pressure Measurements
No full textHigh blood pressure poses a significant health risk of strokes, heart attacks, heart failure, and increases risks of complications from other illnesses. Blood pressure is predominantly taken manually with a pressure cuff by a medical professional which is a single measurement, usually months apart. Continuous blood pressure monitoring could provide a wealth of information about how an individual’s blood pressure actually behaves in their daily life. Accessible and accurate blood pressure monitoring device is a critical medical device as changes in blood pressure are often symptomless. We developed continuous blood pressure sensing using photoplethysmography, an optical method, on an artificial circulatory system integrating sensor data using machine learning. In order to get sufficient data points for our machine learning system to accurately measure blood pressure we created a model system of a human arm using a series of diaphragm pumps, check valves, silicon tubing, silicon to simulate optical properties of skin, and a blood mimicking fluid. I also developed an algorithm to detect chosen features with biological significance from the photoplethysmography waveform to input into our machine learning algorithm.PhysicsBachelors of Science (BS
1,4-Oxazinones as Intermediates in the Construction of Complex Pyridine Products
No full textThis thesis describes the construction of complex pyridine products using 1,4-oxazinones as intermediates. The syntheses of polysubstituted pyridines, 2-azaanthraquinones, and natrual product xylanigripone A are reported through the use of a tandem [4+2]/r[4+2] cycloaddition/cycloreversion sequence using 1,4-oxazinones. In addition, two new methods for the construction of 1,4-oxazinones are presented utilizing safe and inexpensive starting materials, providing novel methods to access substrates in the oxazinone family. This work serves to provide new methods to access biologically relevant products and demonstrates the utility of 1,4-oxazinones as versatile intermediates in the construction of pyridine products.ChemistryBachelors of Science (BS
Emotion Regulation Among Children with Incarcerated Parents: Relations to Caregiver Income and Coping Strategies
No full textParental incarceration is associated with strains on family financial resources and decreases in the existing caregiver's emotional well-being. Parental incarceration is also correlated with children's deteriorating emotional regulation. However, the impact of the existing caregiver’s income and emotional coping strategies on the child’s emotional regulation has not yet received systematic study. This paper examines caregivers’ income and self-reported emotion coping strategies in relation to children’s emotion regulation in a sample of 104 caregiver-child dyads. All caregivers were female and children (43.4% male) were in grades kindergarten through five. Analyses explored the moderating impact of family income and caregiver coping strategies on and their children’s emotion regulation and found significant results for both. Keywords: Parental incarceration, emotion regulation, coping mechanisms, demographic predictors, incomePsychologyBachelors of Science (BS
Characterizing mitochondrial movement and distribution in radial glial neural progenitor cells
No full textPremature neurogenesis in the developing brain can have detrimental impacts on neurodevelopment that give rise to diseases such as microcephaly. Cell proliferation in the brain is controlled by radial glial neural progenitor cells (NPCs) which are essentially the stem cells of the brain. Symmetric division serves the purpose of expanding the progenitor pool by resulting in two NPCs. The progressive differentiation of the brain occurs when NPCs begin to divide asymmetrically to result in a daughter neuron each division while maintaining the progenitor identity. It has been found that the mitochondrial system in stem cells throughout the body contributes to the fate of cells, but this relationship is unclear in NPCs. The mitochondrial network in NPCs is a dynamic system where the organelles are constantly undergoing fission and fusion, and in stem cells with larger and more continuous networks, symmetric division is favored. Even though one of the main roles for mitochondria is energy production through oxidative phosphorylation, NPCs do not rely on this process and instead use glycolysis in the cytosol. It remains a mystery why the NPCs spend resources and energy to transport the mitochondria around the cell. In this thesis, the relationship between the cell’s fate and the movement and localization of its mitochondria is explored. To observe the movement and behavior of mitochondria, they were tagged with a photoactivatable green fluorescent protein (paGFP). Mitochondria in select cell compartments were photoactivated with UV light, so they could be visualized, and the whole NPC and its mitochondria were imaged over multiple days. The distribution of mitochondria within an NPC was analyzed, and my data suggests there are not distinct populations of mitochondria that are controlled independently of each other.BiologyBachelors of Science (BS
The Way Food Should Be: Food Policy, Culinary Advice Literature, and Socialist Identity in the Soviet Union and Russia
No full textThis thesis contributes a focused and analytical view of Soviet food culture and strives to understand the specific nature of Soviet foodways that separate them from both pre- and post-Soviet iterations. Its analysis is rooted in broad political and economic survey, examination of Soviet-era culinary literature, and collation of personal recollections of Soviet-era food culture and argues that the Soviet state consciously inserted itself into food production, distribution, and consumption in a manner entirely new to Russian and perhaps European history and culture. In doing so, it rewrote prior relationships between food consumption and production, leading Soviet consumers to recognize and ascribe a greater sense of agency, ability, and responsibility to the state as a provider figure in everyday life. This new relationship would both help and hinder the state’s survival, as the population’s expectation that the state would provide for them regardless of circumstance created great instability when the Soviet economy faltered. Yet despite all its idiosyncrasies, the Soviet system of food distribution is remembered fondly, and is, in the minds of many post-Soviet individuals, evocative of the society that was lost during the fall of Communism. The three chapters of this thesis make separate yet supporting arguments: Chapter One argues that while the food supply issue occupied a prominent place in the minds of Soviet leaders, their repeated efforts to construct and later reform what would ultimately be an inherently flawed system were hampered by institutional resistance, material scarcity, and ideological limits. Chapter Two argues that the Book of Tasty and Healthy Food [Kniga o vkusnoi i zdorovoi pishche], the pre-eminent Soviet cookbook, reconstructs the relationship between food producers and consumers by demonstrating that in a modern, industrial society like the Soviet Union, food comes not from agriculture, but from the newly developed Soviet food industry. It also emphasizes that as the Soviet economy became more developed, workers would partake in more luxurious and cultured modes of culinary consumption – modes which are taught and demonstrated within the Book. Chapter Three argues that people remember the Soviet food system through three main motifs: the general scarcity of desirable goods, the perception that Soviet-era foodstuffs were healthier than modern alternatives, and the belief that Soviet-era dining was more fulfilling and communal than it is today. These motifs guide nostalgia for the Soviet days in contemporary Russia and their study illuminates the complex truths behind retrospection.HistoryBachelor of Arts (B.A.
Multiply Marginalized: Effects of Race and Gender (Non-) Conformity on Attributions of Gender Identity and Transgender Status
No full textAs individuals are increasingly embodying multiple diverse identities, it is paramount to investigate how the intersections of these identities affect their perception. The present study investigates how race, gender-conformity, and sex assigned at birth (SAAB) affect perceptions of an ambiguous target's gender, as well as subjective opinions held towards the target. In each of two studies, college student and non-college student adult participants (N = 251; N = 288 respectively) viewed one of eight vignettes describing an individual of varying combinations of the variables of interest. They then filled out several perceived identity measures and scales measuring their attitudes towards transgender people of color, including opportunities to freely elaborate on their justifications for answers given. No significant effects for target race were found, but there were many significant interactions between target SAAB and gender expression. Targets whose SAAB and gender expression were incongruent were perceived as less normal, more likely to be transgender and gay, and were assigned to a wider variety of gender categories than those whose SAAB and expression were congruent. Relationships were moderated by gender essentialism and right-wing authoritarianism. Justifications for these perceptions yielded rich qualitative data, offering insights into the differing reasons behind why perceivers make judgements of and categorize ambiguously gendered targets in the ways that they do. Results are discussed in terms of implications of gender non-conformity for social perception research, policy and intervention development, and everyday lives of trans and gender non-conforming individuals.PsychologyBachelors of Arts (BA