Endocrine Disruption Screening: Can Vertebrate Endocrine Disruptors Impact Invertebrate Molting?

Type: Graduate
Author(s): Dalton Allen Biology Justin Hunt Biology Laurel Skrnich Biology
Advisor(s): Marlo Jeffries Biology

Mysid shrimp (Americamysis bahia) have been utilized in routine marine toxicity assessments for decades. While mysids are a well-established model, there a key gaps in understanding how chemical exposure impacts their endocrine systems. Crustacean growth occurs through molting (i.e., shedding old exoskeleton), a process regulated by hormones, primarily ecdysteroids. Ecdysteroids are a class of steroid hormones that share similar chemical structures to vertebrate hormones (i.e., 17β-estradiol and testosterone), which have been suggested to disrupt molting in some invertebrates. Through powerful tools, like transcriptomics, potential genetic biomarkers may be identified following chemical exposure. These biomarkers could provide the basis for future research aimed at screening endocrine disrupting compounds using invertebrate models. The objectives of this work were to 1) assess whether known vertebrate endocrine disruptors (e.g., 17β-estradiol and trenbolone) would induce alterations in molting and growth and, 2) compare gene expression profiles between vertebrate endocrine disruptors and a model ecdysteroid (i.e., ponasterone A) using transcriptomic analysis. Ponasterone A induced predictable alterations in mass, molting, and ecdysteroid-related gene expression, reinforcing both the use of this compound as a positive control and these endpoints for assessing invertebrate endocrine disruptors. Vertebrate endocrine disruptors induced varied responses in the endpoints assessed, but neither acted in a manner comparable to ponasterone A. Future work may investigate the potential for differentially expressed genes identified in the transcriptomic analysis for screening of invertebrate endocrine disruptors.

Investigating diet-induced metabolic syndrome in a typical American versus Mediterranean diet model in C57Bl/6J mice

Type: Graduate
Author(s): Morgan Bertrand Biology Gary Boehm Psychology Logun Gunderson Psychology
Advisor(s): Michael Chumley Biology

Metabolic syndrome (MetS) is a cluster of concurrent cardiometabolic risk factors, including increased waist circumference, hypertension, elevated triglyceride level, reduced high-density lipoprotein (HDL) cholesterol level, and hyperglycemia. The key pathophysiology of MetS is insulin resistance, resulting in a disruption of glucose and lipid metabolism in the liver and adipose tissue, which increases the risk of type II diabetes, cardiovascular disease, and stroke. The development of insulin resistance and related conditions is multifaceted, but risk can be mitigated with lifestyle modifications, including improved nutrition. In the US, a typical American diet (TAD) is full of highly processed foods high in saturated fats and refined sugars and is associated with increased insulin resistance and obesity risk. In contrast, adherence to a plant-based Mediterranean diet (MD) rich in unsaturated fats, fiber, and non-refined carbohydrates has been found to reduce disease risk. Despite the contrasting nutritional compositions, the average macronutrient distributions of these two human diet styles are similar (approximately 50% kcal carbohydrates, 15% kcal protein, and 35% kcal fat). Due to the comparable macronutrient ratios but contrasting nutritional composition, direct comparative analysis could uncover metabolic and cellular differences relating to their associated health outcomes.

There are few rodent studies in the literature that directly compare a TAD and MD. Further, studies often utilize a high-fat diet, consisting of 40-60% kcal fat, or individual nutrient supplements, such as olive oil, rather than comprehensive diet models. To address these limitations, our lab developed comprehensive, macronutrient-matched TAD and MD models that more closely mimic human diets in the U.S. and Mediterranean, respectively. A previous study in our lab found that six months of TAD consumption resulted in elevated body weight, increased inflammation, and excess hepatic lipid deposition, in comparison to the MD. Our current study looked to further characterize MetS under this diet model, specifically investigating obesity, insulin resistance, and dyslipidemia markers. Male and female C57BL/6J mice consumed either the TAD or MD from the age of 4 to 7 months. We found that after three months on diet, there were elevations in hepatic steatosis and serum cholesterol levels in both males and females on the TAD. However, other findings suggested early signs of insulin resistance in TAD males, but not females. Future studies will investigate MetS after 6 months on diet to better elucidate insulin resistance development and potential sex differences.

Effects of Parental Diet on the Offspring's Epigenome and Expression of Genes Associated With Alzheimer's Disease

Type: Undergraduate
Author(s): Nicholas Boehly Biology Bridey Brown Biology Emersyn Jorski Biology
Advisor(s): Dr Matthew Hale Biology

Nick Boehly, Bridey Brown, Emersyn Jorski, Matthew Hale

Texas Christian University, Department of Biology

Previous studies have shown that nutrition plays a key role in influencing epigenetic markers. Additionally, changes in gene expression have been linked to the development of Alzheimer’s disease (AD). However, it is unclear how, and to what effect, nutrition influences changes in the epigenome. To that end, we divided mice into groups and exposed them to two different diets 1) a typical American diet (TAD) and 2) a Mediterranean diet (MD). Although it is known that diet can induce epigenetic modification, it is unknown if these changes are heritable. There has been little research that has focused on the offspring of the mice fed with these diets. Therefore, this experiment will focus on how the diets of parental mice affect their offspring’s methylation patterns of previously identified candidate genes linked to the development of AD. Prefrontal cortex samples from F1 mice, whose parents were exposed to MD or TAD, were removed, and the RNA was extracted and reverse transcribed into cDNA. This cDNA will display levels of expression by 10 distinct genes that have been linked to AD in previous studies. Our goal is to identify correlations between nutrition and the development of AD through modifications of gene expression. Moreover, this data will help illustrate how inheritance of epigenetic modifications can influence gene expression in subsequent generations.

Investigation of the Presence and Impact of Heavy Metals in the Trinity River

Type: Undergraduate
Author(s): Drew Carlton Biology Dalton Allen Biology Marlo Jeffries Biology Katie Solomons Biology Reagan Spickard Biology
Advisor(s): Marlo Jeffries Biology

The Trinity River is an important body of water to the state of Texas as it is a source of drinking water for the Dallas-Fort Worth and Houston Metropolitan areas, a popular location for recreational activities, and an ecologically significant habitat for a variety of organisms. Due to its urban location, the Trinity River is subject to potential heavy metal pollution from wastewater treatment plant discharge, road runoff, and industrial activities. Heavy metal exposure has been shown to cause significant adverse impacts on aquatic organisms; thus, this project aimed to evaluate the presence and biological impact of heavy metals in sediment and surface water samples collected from the Trinity River. Water samples collected from the Trinity River were tested for the presence of heavy metals using ICP-OES. Larval fathead minnows were also exposed to sediment and surface water samples collected from the Trinity River and gene expression levels of five biomarkers were measured. Metallothionein was used as a biomarker of exposure to heavy metals, catalase and superoxide dismutase were used as biomarkers of oxidative stress, and heat shock proteins 70 and 90 were used as biomarkers of generalized stress. The results of this study provide insight into the extent of heavy metal contamination in the Trinity River, as well as its potential impact on aquatic life.

Efficacy of Repurposed ClpXP Protease Inhibitors in Bacillus anthracis Sterne Strain

Type: Undergraduate
Author(s): Braden Chadwick Biology Alex Caron Biology Sheridan O'Coyne Biology Katherine Richey Biology Mikaela Stewart Biology
Advisor(s): Shauna McGillivray Biology

As increasing antimicrobial resistance continues to limit treatment options for bacterial infections, several new approaches have sought to avoid the challenges faced by traditional antibiotics. One such approach is targeting virulence factors, which are necessary for pathogens to evade host defenses and establish infection but not for survival outside the host. This strategy could provide an effective form of treatment while reducing selective pressures for bacteria to evolve resistance mechanisms. Studies have shown that the ClpXP proteolytic complex is essential for virulence in Bacillus anthracis and that deletion of the ClpX subunit increases sensitivity to the cell-envelope-targeting antibiotics penicillin and daptomycin as well as the human antimicrobial peptide LL-37. Previously, we used computational modeling to identify commercially available inhibitors of the ClpXP complex and demonstrated that one, ritanserin, mimics the phenotype of a B. anthracis ΔclpX knockout mutant in antimicrobial susceptibility assays. In this study, we evaluated ritanserin in comparison to four other inhibitors identified during the same screen—siramesine, xaliproden, fluspirilene, and R59022—by determining the fractional inhibitory concentration (FIC) index of each when used in combination with penicillin. Notably, all inhibitors used except R59022 have undergone at least phase II clinical trials for other purposes. We found that two out of the three inhibitors with the highest predicted binding affinity, ritanserin and siramesine, exhibited synergistic interaction with penicillin, while the remainder of the interactions were indifferent. Our results further demonstrate the potential of structural biology techniques to identify and repurpose existing drugs for use as novel antibiotics.

Type: Undergraduate
Author(s): Nia Chambers Biology
Advisor(s): Giri Akkaraju Biology

Chronic inflammation is a major contributor to neurological damage in diseases such as Alzheimer’s, which currently affects nearly 7 million Americans. The NF-kB signaling pathway plays a critical role in mediating inflammatory responses, as it regulates the expression of several pro-inflammatory cytokines, such as TNF-alpha, that exacerbate neuroinflammation. This study investigates the effectiveness of novel compounds in regulating TNF-alpha induced NFkB activation, using a luciferase reporter assay.

Expanding the Potential for Bacteriophage Therapy: Isolation of Phages against ESKAPE Pathogens

Type: Undergraduate
Author(s): Sophie Cronk Biology Cassidy Hunter Biology Katherine Lesslie Lesslie Biology Aeron Pennington Biology
Advisor(s): Shauna McGillivray Biology

Expanding the Potential for Bacteriophage Therapy: Isolation of Phages against ESKAPE Pathogens

Sophie Cronk, Katherine Lesslie, Cassidy Hunter, Aeron Pennington, Shauna M McGillivray

Bacteriophages are viruses that selectively infect bacteria and propagate to overtake the host species.

They are also being developed as a treatment for otherwise drug-resistant infections. Though

bacteriophage therapy has not been FDA approved; it has been used in cases of compassionate care.

Because of the success in these cases, bacteriophage is offering a promising alternative to antibiotics

in the fight against antibiotic resistance. One issue in mainstream bacteriophage use is them

selectivity. Phages infect a specific bacterial species or a particular strain within the species.

Therefore, multiple phages may be required in a ‘phage cocktail’ to ensure there is a phage infects a

target bacterial strain. The goal of our bacteriophage study was to gather data about

where phages are heavily populated and to refine protocols to ensure optimal bacteriophage

collection. Bacteriophage that attacks different bacterial hosts tends to be found in locations

that commonly accumulates that specific host bacteria. A secondary goal is to isolate as many phages as

possible against bacterial species known as the ESKAPE pathogens. The ESKAPE pathogens are Staphylococcus aureus, Enterobacter

aerogenes, Pseudomonas aeruginosa and Klebsiella pneumoniae. These are clinically relevant

because their antibiotic resistance poses a threat to public health due to their ability to cause severe

infections. We have successfully isolated bacteriophage for Pseudomonas aeruginosa, Klebsiella,

and Enterobacter and we are actively exploring different environments for phage that will infect

S. aureus.

Investigating the effects of patient variants and phosphorylation on the BRCA1/PALB2 interaction

Type: Undergraduate
Author(s): Audrey Dolt Biology Chrissy Baker Biology Precious Castillo Biology Hayes Martin Biology Jamison Speed Biology
Advisor(s): Mikaela Stewart Biology

BRCA1 and PALB2 proteins suppress tumor formation by promoting homologous recombination when DNA damage has occurred. Mutations in BRCA1 and PALB2 are associated with a higher prevalence of breast and ovarian cancers. It is established that phosphorylation of BRCA1 and PALB2 occurs in or near the coiled-coil region of both proteins. This domain is utilized by both proteins to heterodimerize, so we hypothesize that phosphorylation events could affect BRCA1/PALB2 interaction affinity. We are using Isothermal Titration Calorimetry and Circular Dichroism to determine if phosphorylation affects the structure or function of minimized binding domains from BRCA1 and PALB2. We will present our findings from the PALB2 phosphorylation sites which, contrary to our hypothesis, do not affect binding to BRCA1, as well as forthcoming data on the BRCA1 phosphorylation sites. In addition, we are using the minimized constructs and similar techniques to study questions regarding the effect of variants of unknown significance on the structure and function of these regions. While we have many variants remaining to test, thus far we find that the coiled-coil structure is destabilized by the introduction of proline variants in particular; therefore these variants disrupt the binding between PALB2 and BRCA1 and are more likely to be detrimental. We will present a summary of the variants tested to date and our working hypothesis regarding structure and function disruptions in the coiled-coil domains of BRCA1 and PALB2.

The impact of novel Alzheimer’s Disease therapeutics on the activation of the pro-inflammatory transcription factor NF-ⲕB

Type: Undergraduate
Author(s): Lal Durmaz Biology
Advisor(s): Giridhar Akkaraju Biology

Inflammation is a natural and beneficial response to injury and pathogen invasion. However, chronic inflammation is linked to the progression of various neurodegenerative diseases. Although the exact etiology is unknown, Alzheimer’s disease is associated with the overactivation of the NF-kB inflammatory pathway. NF-kB is a transcription factor that, in an unstimulated cell, is sequestered in the cytoplasm as a complex with its inhibitor, IκBα. When the pathway is activated by an external signal, IκBα is phosphorylated and subsequently degraded in the proteasome. Liberated NF-κB translocates to the nucleus, where it acts as a transcription factor for pro-inflammatory genes, highlighting its potential as a therapeutic target. Our research investigates the exact point of interference of novel anti-inflammatory drugs (provided by P2D Biosciences) with the NF-kB pathway through Western blotting and immunofluorescence.

Characterizing a C. elegans Model for Oxidative Stress Response

Type: Undergraduate
Author(s): Nicholas Findlater Biology Madelynn Farhat Biology
Advisor(s): Thushara Galbadage Interdisciplinary Giridhar Akkaraju Biology

Neurodegenerative diseases such as Parkinson’s and Alzheimer’s disease are characterized by progressive neuronal loss, often driven by oxidative stress. The accumulation of reactive oxygen species (ROS) contributes to cellular damage, making oxidative stress a key factor in disease pathology. Caenorhabditis elegans, a genetically tractable model with conserved stress response pathways and neuronal structures, provides an effective system for studying oxidative stress and neurodegeneration. This study aims to establish an optimized oxidative stress assay in C. elegans to evaluate protective effects against ROS-induced damage. Wild-type (N2) C. elegans were synchronized via a bleaching protocol to generate a uniform population of young adults. Lifespan and survival assays were performed using tert-butyl hydroperoxide (tBHP) to induce oxidative stress, testing concentrations of 10, 1, 0.1, and 0.01 mM. Higher concentrations (10 and 1 mM) resulted in rapid mortality of C. elegans within 3 and 9 hours, respectively, whereas lower concentrations (0.1 and 0.01 mM) allowed survival beyond 12 hours. Based on these findings, an optimal tBHP concentration will be used to further refine this oxidative stress model. This study provides foundational data for investigating the efficacy of potential antioxidant molecules in reducing ROS-related damage. By using the C. elegans model, future research will focus on identifying molecular mechanisms of oxidative stress response and evaluating therapeutic candidates for neurodegenerative diseases.

Genetic Variation in Alligator Weed Influences Herbicide Effectiveness Across Regions

Type: Undergraduate
Author(s): Namandeep Gill Biology Dean Williams Biology
Advisor(s): Dean Williams Biology

Alligator weed (Alternanthera philoxeroides) is a highly invasive species that threatens waterways, agriculture, and ecosystems worldwide. While herbicide treatments have successfully managed populations in Mississippi, they have been less effective in Australia and New Zealand. This research investigated whether genetic differences among populations contribute to these inconsistencies in control effectiveness. To test this, we genotyped alligator weed samples from Mississippi, Australia, and New Zealand using chloroplast DNA markers to identify haplotypes. Results revealed significant genetic variation among regions. Mississippi populations exhibited greater haplotype diversity, with Ap1 and Ap3 being dominant, whereas Australia and New Zealand were primarily composed of Ap2, Ap3, and Ap5. The genetic lineages used in Mississippi herbicide trials did not directly match those found in Australia and New Zealand, suggesting that differences in herbicide response may be linked to genetic variation. These findings indicate that current herbicide trials may not accurately predict effectiveness in non-U.S. regions. Future testing on genetically relevant populations will improve control strategies, ensuring more effective management of alligator weed globally.

EmpowerHer STEM Club

Type: Undergraduate
Author(s): Lilli Gonzales Biology Daisy Carrillo Environmental Sciences Hermela Leul Nutritional Sciences Zoie Munoz Biology Kelley Wyatt Biology
Advisor(s): Christina Ayala Biology

EmpowerHer STEM Club is an after-school program dedicated to encouraging young girls to explore careers in science, technology, engineering, and mathematics (STEM). In collaboration with E.M. Daggett Elementary School, the program seeks to address the gender gap in STEM fields, where women currently hold only 28% of STEM occupations. Research suggests that early mentorship plays a crucial role in shaping young women's academic and career aspirations.
EmpowerHer STEM Club provides mentorship and hands-on learning experiences to inspire and support young girls in their STEM interests. The program introduces students to diverse STEM fields through interactive experiments that complement their classroom curriculum. Additionally, participants learn about various STEM careers and the achievements of influential women in these fields. Through this engaging approach, EmpowerHer STEM Club fosters curiosity, confidence, and a passion for STEM while building connections with the next generation of leaders.

The Effects of Novel Anti-Inflammatory Drugs on LPS-Induced Cytokine Gene Expression in BV2 Cells

Type: Undergraduate
Author(s): Ana Herget Biology Giridhar Akkaraju Biology
Advisor(s): Giridhar Akkaraju Biology

Alzheimer’s Disease (AD), the most common form of dementia, currently impacts almost seven million people in the United States over the age of 65. It is predicted that by 2060 over 13 million people in the United States will be affected by AD, which is why there is a growing demand for treatments. Amyloid ꞵ plaques and phosphorylated tau proteins are both associated with the progression of the AD pathology since they play a role in the disruption of neuronal integrity. These aggregated proteins along with other molecules, such as lipopolysaccharide (LPS), lead to increased inflammation by activating the NFκB pathway. The NFκB pathway controls the production of pro-inflammatory cytokines, such as interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNFɑ); however, if it is overactive, it can lead to harmful inflammation.The company P2D Biosciences provides novel compounds designed to reduce inflammation, but the exact mode of action of these compounds is unknown. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) can be utilized to measure cytokine mRNA from BV2 cells that have been pretreated with the drugs and then with LPS. In this project we screened multiple compounds provided by P2D Biosciences to evaluate their use as anti-inflammatory agents to treat AD.

Investigating the ubiquitin ligase activity of BRCA1 from C. elegans

Type: Undergraduate
Author(s): Lauren Herrington Biology
Advisor(s): Mikaela Stewart Biology

BRCA1 is a tumor suppressor protein that normally acts with its partner, BARD1, to facilitate DNA repair, regulation of the cell cycle, and regulation of gene expression. The Caenorhabditis elegans homologs of BRCA1 and BARD1, BRC-1 and BRD-1, respectively, retain these key functions and thus make C. elegans a suitable model organism for studying the functions of BRCA1. While the functions of BRCA1 and BRC-1 are well characterized, the molecular mechanisms by which these functions are carried out is still unclear. For example, BRCA1 and BRC-1 possess E3 ubiquitin ligase activity towards histone H2A in nucleosomes, but it is unknown how this contributes to tumor suppression. While inherited mutations that disrupt tumor suppression lack E3 ligase activity, they also interfere with other critical molecular functions, such as BARD1 binding. To pinpoint the role of E3 ligase activity, we aim to characterize a mutant construct of BRC-1 in C. elegans that lacks E3 ubiquitin ligase activity towards histone H2A but retains the ability to bind BRD-1. In vitro ubiquitination assays demonstrate that our candidate for this mutant of BRC-1, Trip A, is ligase-dead towards histone H2A in nucleosomes. Co-purification of BRC-1 and BRD-1 in which only BRC-1 contained the histidine tag revealed that BRC-1:BRD-1 binding is retained in the Trip A mutant. While these results demonstrate that Trip A meets in vitro requirements for a ligase-dead mutant, further in vivo experiments are needed to confirm its suitability. If confirmed as a suitable ligase-dead mutant through in vivo experiments, Trip A can be expressed in C. elegans to identify which functions of BRC-1 depend on E3 ubiquitin ligase activity towards histone H2A in nucleosomes.

Identifying the nucleosome ubiquitylation role of BRCA1 in transcriptional regulation using C. elegans

Type: Undergraduate
Author(s): Elizabeth Hoff Biology
Advisor(s): Mikaela Stewart Biology

BRCA1 is a tumor suppressor protein that facilitates DNA damage repair, cell cycle checkpoints, and gene expression in humans. The presence of pathogenic mutations in the BRCA1 protein leads to a predisposition to breast and ovarian cancers in humans; these pathogenic mutations can lead to the dysregulation of enzymatic activity and gene expression. It is hypothesized that enzymatic activity of BRCA1 and its ability to regulate gene expression are linked. The gene expression of estrogen-metabolism genes by BRCA1 is mediated, in-part, by the ability of BRCA1 to facilitate the mono-ubiquitylation of nucleosomes on the H2A histone. Our lab is interested in understanding which DNA damage repair and gene expression functions of BRCA1 rely on mononucleosome ubiquitylation. In Caenorhabditis elegans, the BRCA1 homolog, BRC-1, retains the key functions of BRCA1, making C. elegans a suitable model organism to evaluate which functions of BRCA1 rely on nucleosome ubiquitylation. To explore nucleosome ubiquitylation by BRC-1 in C. elegans, we compare three strains of C. elegans, including a wildtype strain, a complete knockout of BRC-1, and an engineered mutant. This engineered mutant contains two point mutations that alter the ability of BRC-1 to interact with the nucleosome to complete ubiquitylation of the H2A histone. We suggest that our proposed mutant repels BRC-1 from the histone to prevent ubiquitylation, yet retains all other BRC-1 functions. We hypothesize that this will hinder the repression of cyp genes, which code for enzymes that catalyze the process that converts estrogen into various metabolites, some of which are harmful. Overexpression of these genes can lead to the accumulation of harmful estrogen metabolites, which can lead to tumorigenesis in estrogen-metabolizing tissues. To assess this, we compare the expression levels of cyp genes, which are repressed in the wildtype strain containing a functional copy of BRC-1. If mononucleosome ubiquitylation is required for transcriptional repression in C. elegans, in the engineered mutant strain, we expect to see elevated levels of cyp gene expression, as also seen in the complete BRC-1 knockout strain. Through understanding the mono-ubiquitylation of nucleosomes by BRC-1 in C. elegans, we can better interpret the genetic variations of BRCA1 in humans and better inform and treat patients with detrimental BRCA1 mutations.

How does the heterogeneity of vector control vs. environmental concerns influence the dynamics of vector-borne diseases

Type: Undergraduate
Author(s): Redon Limani Biology Jing Jiao Biology Grant Xiong Biology
Advisor(s): Jing Jiao Biology

This study develops an integrated mathematical model to explore the dynamics of mosquito-borne disease transmission between two patches within the context of changing environmental conditions and varying human behaviors. By incorporating factors such as migration rates, environmental concerns, and control efforts influenced by community risk perception, the model evaluates how these elements interact to shape disease outcomes.
Key findings indicate that effective disease control is highly dependent on the alignment between public health interventions and environmental sustainability. The model reveals that higher environmental concerns tend to moderate aggressive control measures, potentially reducing their effectiveness. Conversely, increased migration can either mitigate or exacerbate disease spread depending on the existing control strategies within each community.
The value of this research lies in its potential to guide policymakers in crafting disease control strategies that are both effective and environmentally sensitive. By integrating environmental and behavioral factors into disease modeling, the study provides a nuanced understanding of how different approaches can impact public health outcomes, offering a roadmap for more holistic and sustainable disease management practices.

The enzymatic role of nucleosome ubiquitylation by BRCA1 in C. elegans

Type: Graduate
Author(s): Meagan McMann Biology Nathalie Carlon Biology Lucy McCollum Biology
Advisor(s): Mikaela Stewart Biology

BRCA1 protects genomic stability by signaling for the homologous recombination pathway, DNA repair, and transcriptional regulation. A pathogenic mutation in the BRCA1 region causes a higher predisposition to the development of breast and ovarian cancer. Our lab is exploring the different enzymatic functions of BRCA1 by looking at its role in histone ubiquitylation, leading to transcriptional regulation of certain parts of the genome. Join us to see our plan for connecting molecular mechanisms of a large, multi-functional gene to the phenotype of an organism. A homolog of BRCA1 is conserved in C. elegans as BRC-1. We propose that mononucleosome ubiquitylation is a key mechanism contributing to the cellular functions of BRC-1. Understanding the significance of mononucleosome ubiquitylation in BRC-1 with C. elegans gives insight into the mechanisms of genetic variations in BRCA1 and further expands C. elegans’ function as a model organism. We have generated a C. elegans mutant with two point mutations that alter the ability of BRC-1 protein to interact with the nucleosome and ubiquitinate histone H2A while retaining all other functions. We hypothesize this mutation increases DNA damage accumulation and disrupts transcriptional regulation to establish nucleosome ubiquitylation as a necessary precursor for these, but likely not all, BRC-1 functions. We compare three strains of C. elegans (wildtype, brc-1 knockout, and our mononucleosome ubiquitylation-deficient mutant) in different conditions designed to induce cellular stress or DNA damage accumulation. We find that BRC-1 nucleosome ubiquitylation contributes to embryonic survival under standard conditions as well as DNA damage-inducing conditions. We also share preliminary results regarding the role of nucleosome ubiquitylation in transcription regulation and reactive oxygen species generation. Our findings further the understanding of the many enzymatic functions of the large BRCA1 gene.

Investigating Mercury Transfer from Aquatic to Terrestrial Food Webs: The Influence of Distance from Pond Shorelines on Methylmercury Concentrations in Arctic Wolf Spiders

Type: Graduate
Author(s): Camryn Middlebrooks Biology Aleah Appel Biology Sommerlyn Babineau Biology Kurt Burnham Biology Ethan Cary Biology Titus Crawford Biology Sage Dale Biology Charlie Duethman Biology Aidan Duffield Biology Piper Dumont Biology Skyler Dunn Biology Madeline Hannappel Biology Sydney Hill Biology Ramsey Jennings Biology Ben Katzenmeyer Biology Chidi Mbagwu Biology David Peebles Biology Benjamin Strang Biology Emma Sullivan Biology Lance Viscioni-Wilson Biology Kimberlee Whitmore Biology Tyler Williams Biology David Wright Biology
Advisor(s): Matt Chumchal Biology

Mercury is emitted from various anthropogenic processes in temperate and tropical regions and is transported to northern latitudes via air and ocean currents. Although there are few point sources of mercury in the Arctic, elevated mercury levels have been observed in Arctic predators such as marine mammals, seabirds, fish, and spiders. This is concerning due to mercury’s known neurotoxic and teratogenic effects. Mercury deposited in the Arctic can be converted into its bioavailable form, methylmercury (MeHg), by aquatic bacteria. It can then be transferred into nearby terrestrial habitats by aquatic emergent insects. A previous study indicated that Arctic wolf spiders (Pardosa glacialis) collected from the shoreline of ponds had elevated concentrations of MeHg. In temperate zones, adult aquatic insects typically disperse within 30 meters of freshwater sources, suggesting that upland predators may consume fewer emergent aquatic insects, thereby reducing their contamination from these sources. While Arctic wolf spiders are ubiquitous predators across the tundra, it is unclear whether spiders collected in upland habitats are similarly contaminated with MeHg. The purpose of this study was to investigate the movement of mercury from aquatic to terrestrial food webs on the Pituffik Peninsula of northwest Greenland. Specifically, we examined the effects of shoreline proximity on mercury concentrations in Arctic wolf spiders. We collected Arctic wolf spiders and their insect prey at varying distances (0m, 10m, and 35m) from six freshwater ponds. We found a positive relationship between mercury concentrations and body size in P. glacialis. Spiders captured 35 meters away from the shoreline had significantly lower mercury concentrations than those captured at 0m or 10m from the shoreline. These results suggest that the dispersal of Arctic emergent aquatic insects declines with increasing distance from the shoreline and that emergent insects are an important source of mercury for Arctic wolf spiders.

New Smiles Drive

Type: Undergraduate
Author(s): Alexandra Much Biology Aimee Garibay Interdisciplinary Annie Loomis Biology Sarina Schwarze Biology Kameryn Smudde Nutritional Sciences
Advisor(s): Sarah Jung Biology

Oral health is a critical component of overall well-being, yet many individuals in underserved communities lack access to essential dental care and hygiene resources. The New Smiles Drive is a student-led initiative dedicated to improving oral health education and access to hygiene supplies in the Fort Worth community. Through the TCU Tooth Fairies program, we present at elementary schools, engaging students in interactive lessons on proper brushing and flossing techniques to foster lifelong oral hygiene habits. Additionally, we donate hygiene kits—containing toothbrushes, toothpaste, floss, and a laminated educational card outlining proper brushing steps in both English and Spanish—to Mercy Clinic, which provides medical and dental care to uninsured patients, as well as to local homeless shelters. By combining education with tangible resources, New Smiles Drive aims to promote preventive dental care and address disparities in oral health access.

In Vitro Evaluation between 5-LO Inhibitor, Zileuton, and Antifungal Activity Against Cryptococcus

Type: Undergraduate
Author(s): Khoi Nguyen Biology Natalia Castro Lopez Biology
Advisor(s): Natalia Castro Lopez Biology

Total Mercury (THg) Levels in Tricolored Bats (Pipistrellus subflavus) in East Central Texas

Type: Undergraduate
Author(s): David Peebles Biology Cami Middlebrooks Biology Benjamin Strang Biology
Advisor(s): Matt Chumchal Biology

Mercury (Hg) is a trace element metal with toxic effects on wildlife, including bats. Texas is the largest producer of mercury pollution in the United States, yet only 2 other studies have measured the concentration of mercury in bats. We measured total mercury concentrations (THg) in fur (n=57) in the endangered species Tricolored bats (Pipistrellus subflavus) collected from two culverts in Fresstone County in East Central Texas. Fur THg concentrations were compared between sex, culverts, and previous studies in the U.S.. There was no significant difference in THg between sex or culvert, but there was a significant difference with the Tricolored bats in the Northeastern U.S.. However, the THg values were not significantly different from those of previous studies conducted in Texas. Additionally, the THg concentrations were compared with the 10 ug/g toxicity threshold levels commonly used, with 5.2% of Tricolored bats in this study exceeding this toxicity threshold. This suggests that THg may pose a risk to the health of bats in East Central Texas, and protective measures need to be implemented to protect this species.

Investigating the role of fused msrA/B and clpX in the resistance to cell-wall targeting antibiotics in Bacillus anthracis Sterne

Type: Graduate
Author(s): Aeron Pennington Biology Josey Austin Biology Salina Hona Biology Kelsey Waite Biology
Advisor(s): Shauna McGillivray Biology

The ClpXP protease plays a critical role in bacterial responses to external stressors, protein recycling, and virulence. The protease is highly conserved and composed of two subunits: ClpX, a regulatory ATPase, which recognizes and unfolds proteins, and ClpP, the proteolytic subunit. Our lab has identified that ClpX plays a role in resistance to cell-envelope targeting antibiotics and is critical for virulence in B. anthracis Sterne. However, it is unlikely that ClpX is directly mediating these effects. Rather, these effects are likely due to the dysregulation of the protein network maintained by ClpXP, which includes proteins involved in gene expression, such as transcription factors. Previously, we conducted a microarray and identified 119 differentially expressed genes between wild-type B. anthracis Sterne and a ΔclpX strain. One of the genes identified from the microarray is msrA/B, a fusion of the msrA and msrB methionine sulfoxide reductases (msr). Msr enzymes restore functionality to oxidized methionine residues; MsrA reduces S-form Met(O), and MsrB reduces R-form Met(O). Research with these enzymes has primarily focused on their role in resistance to reactive oxygen species (ROS). However, in S. aureus, msrA1 and msrB expression was induced upon exposure to oxacillin and other cell-wall active antimicrobial agents and not by ROS, indicating a potential connection between msrA/B and cell wall-targeting antibiotics. In B. anthracis Sterne, loss of msrA/B increases susceptibility to penicillin and vancomycin. However, this phenotype is not seen with cell-membrane targeting agents such as daptomycin, suggesting that the role of msrA/B in antimicrobial resistance may be limited to cell-wall active antibiotics. We are currently investigating the role in resistance to ROS but have seen no susceptibility to either H2O2 or paraquat. Future studies will look at changes in msrA/B expression in response to a variety of antibiotics and ROS stressors to better understand the role of this enzyme in regulating the response to these stressors in B. anthracis.

Examining oxidative stress models in mouse neuron HT-22 cells to explore neuroprotective features of antioxidant compounds.

Type: Undergraduate
Author(s): Caleb Pryor Biology Michael Chumley Biology Raleigh Robinson Biology
Advisor(s): Michael Chumley Biology

Alzheimer’s disease (AD) is a progressive neurodegenerative disease that affects millions worldwide and has shown increasing prevalence. The pathological hallmarks of AD include amyloid-beta (Aβ), tau hyperphosphorylation, and neuroinflammation. It has become increasingly apparent that oxidative stress from reactive oxygen species (ROS) accumulation plays a crucial role in AD disease progression. ROS contributes to neuronal dysfunction and death by inducing lipid peroxidation, mitochondrial impairment, and chronic inflammation. We utilized the HT-22 mouse neuronal cell line to investigate oxidative stress and potential neuroprotection in vitro following glutamate induced oxidative stress. To assess oxidative damage and neuron death, we utilize the MTT assay to measure cell viability following glutamate treatment. Novel antioxidant compounds synthesized from Dr. Green’s labs have been shown to be radical scavengers and increase expression of antioxidant pathways. We additionally pre-treated HT-22 cells with these novel antioxidant compounds prior to glutamate exposure to evaluate their effectiveness in scavenging ROS and preventing oxidative damage. Results from these experiments will lay the foundation for further testing to determine the mechanism in which these novel antioxidants show neuroprotective effects, which could provide valuable insight into antioxidant based therapeutic strategies for AD and other neurogenerative diseases.

Influence of LPS-Treated BV2 Supernatants on Glutamate-Induced Ferroptosis in HT22 Cells

Type: Undergraduate
Author(s): Raleigh Robinson Biology Caleb Pryor Biology
Advisor(s): Michael Chumley Biology Gary Boehm Psychology

Alzheimer’s disease (AD) was the fifth leading cause of death in people over 65 in 2021, and it is expected that 13 million Americans will have AD by 2050. AD is a neurodegenerative disease that is characterized clinically by the onset of memory loss and cognition decline in aging populations. These clinical manifestations of AD are a result of neuronal cell death. While our knowledge of the exact pathology of AD is still evolving, inflammation of the central nervous is known to be a factor in the onset and progression of AD. Microglial cells are one major cell type responsible for this inflammation. Microglial overactivation, which leads to the overproduction of proinflammatory cytokines, is thought to be a cause of the chronic inflammation seen in AD. Additionally, ferroptosis, which is a regulated form of cell death characterized by iron-dependent lipid peroxidation, is thought to be a major mechanism by which neurodegeneration occurs in AD. HT22, an immortalized cell line of mouse hippocampal neurons, are a commonly used model for studying ferroptosis. Furthermore, BV2 cells are an immortalized cell line of mouse microglial cells that produce inflammatory cytokines that can be removed in their “conditioned” media. We treated HT22 cells with glutamate to induce ferroptosis, and also with BV2-conditioned media, and measured the cell death via an MTT assay to investigate whether the proinflammatory cytokines produced by microglial cells also induces the neuronal cell death that occurs via ferroptosis. These studies are ongoing.

SEX RATIOS OF SILVER-HAIRED BAT (LASIONYCTERIS NOCTIVAGANS)​ FATALITIES AT WIND ENERGY FACILITIES IN SOUTHERN INDIANA​

Type: Undergraduate
Author(s): Gabby Ross Biology
Advisor(s): Dr. Dean Williams Biology

Wind energy is considered one of the fastest growing renewable energy sources. However, bat collision mortality has become an increasing issue for migratory bat species over the years. Researchers are interested in a sex bias in the mortality rates at wind farms. If females are being disproportionately killed, the population will not sustain itself over time and their numbers will decrease. The goal of my study was to determine the sex ratio of silver-haired bats killed at a wind farm and determine if females are experiencing higher mortality than males. These data allow scientists to implement curtailment that reduces collision fatalities. Curtailment is the turning off of wind turbines on low wind speed nights, the nights where bat mortalities are highest. Researchers can also use the information to target curtailment when females are at their highest risk for collisions. I extracted DNA from 66 bat samples originating from a wind farm in Southern Indiana. To determine the species for a subset of the samples I sequenced a portion of the mitochondrial cytochrome oxidase I gene which is the DNA barcode region that can be used to identify species, I then used X and Y genetic markers to determine the sex of all samples. Of the 66 samples, 9 were spot checked for species identification via sequencing and were identified as silver-haired bats. Out of the 66 samples, 29 (43%) samples were identified as female and 37 (66%) were identified as male. This ratio did not differ from a 50:50 sex ratio (x2=0.97, p = 0.32). We can conclude that our sample set has a 50:50 sex ratio of males to females for silver haired bats. We compared our data to previous studies on silver haired bats and noticed a similar pattern for several other states in the US. The only state to have a statistically significant difference in their sex ratio of females to males was Ohio, which had a sex ratio of 2.1 females for every male. Since the results indicate a 50:50 sex ratio, curtailment during migration periods could be equally effective for both sexes to maintain the population of silver haired bats over time. Further research also indicates that acoustic deterrence is an unequivocally effective method for deterring bats from wind turbines.