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

Type: Graduate
Author(s): Dalton Allen Biology Justin Hunt Biology Marlo Jeffries Biology Laurel Skrnich Biology
Advisor(s): Marlo Jeffries Biology
Location: Basement, Table 9, Position 1, 1:45-3:45

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
Location: SecondFloor, Table 6, Position 2, 11:30-1:30

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
Location: SecondFloor, Table 9, Position 1, 1:45-3:45

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
Location: Basement, Table 15, Position 2, 1:45-3:45

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
Location: Basement, Table 15, Position 1, 11:30-1:30

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
Location: SecondFloor, Table 8, Position 1, 11:30-1:30

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
Location: Third Floor, Table 5, Position 1, 11:30-1:30

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 Mikaela Stewart Biology
Advisor(s): Mikaela Stewart Biology
Location: Basement, Table 11, Position 1, 11:30-1:30

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
Location: Third Floor, Table 3, Position 3, 1:45-3:45

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
Location: SecondFloor, Table 9, Position 1, 11:30-1:30

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.