Filter and Sort







BIOL2021ALENIUSTHALHUBER55223 BIOL

A question of where: differential diets, growth rates, and survival of captive-bred hatchling Texas horned lizards (Phrynosoma cornutum) reintroduced at separate locations in central Texas.

Type: Graduate
Author(s): Rachel Alenius-Thalhuber Biology
Advisor(s): Dean Williams Biology
Location: Zoom Room 6, 01:42 PM

The reintroduction of captive-bred animals has been increasingly utilized for the conservation of many species. However, few studies have focused on the importance of environmental factors and resource availability in the success of wildlife reintroductions. The goal of this study was to see if location influences the short-term reintroduction success of captive-bred Texas horned lizards (Phrynosoma cornutum). Specifically, I monitored diets, growth rates, and survival of over 250 lizards reintroduced to 2 locations in Mason Mountain Wildlife Management Area (Mason County, TX) for 3 months. Diet, growth rates, and survival all differed between the two locations. The findings of this study suggest that environmental factors can play an important role in the reintroduction success of Texas horned lizards. Future research will focus on identifying specific habitat characteristics that may contribute to the observations of this study such as prey availability, vegetation, thermal habitat quality, and soil permeability.

(Presentation is private)

BIOL2021ALI8073 BIOL

Mechanisms of Zinc Oxide Antibacterial Activity in Staphylococcus aureus

Type: Undergraduate
Author(s): Iman Ali Biology Alex Caron Biology John Reeks Physics & Astronomy
Advisor(s): Shauna McGillivray Biology Yuri Strzhemechny Physics & Astronomy
Location: Zoom Room 3, 03:11 PM

Antibiotic resistance has been increasing rapidly; however, the amount of new and effective antibiotics is declining. One area of growing interest is the use of metal nanoparticles because they are relatively easy to make and can be synthesized into different shapes, sizes, and with various chemical properties. In particular, zinc oxide nanoparticles have shown to be effective against various bacterial strains; however, the mechanism that zinc oxide utilizes to exhibit its antimicrobial activity is still unknown. It is also not clear what properties of zinc oxide such as size or proximity to bacterial cells are critical for its antimicrobial activity. In order to gain a better understanding of the mechanism behind zinc oxide’s antimicrobial activity, we tested Staphylococcus aureus with various zinc oxide particles under different conditions. Specifically, we looked at whether particle size, contact with bacterial cells, and media type influenced antimicrobial activity. Our results suggest that particle size does not influence zinc oxide activity, but media type significantly impacts antimicrobial activity. Physical contact, although more effective, is not absolutely required to see inhibition of bacterial growth. Understanding the mechanisms that zinc oxide utilizes may guide design for future particles that will improve their effectiveness.

View Presentation

BIOL2021ALLEY23145 BIOL

The Effects of Novel Antioxidant Treatment on Microglial Cell Function in BV2 Cells

Type: Undergraduate
Author(s): Carly Alley Biology Paige Braden Psychology Caroline O'Connor Biology Margaret Vo Biology
Advisor(s): Michael Chumley Biology Kayla Green Chemistry & Biochemistry
Location: Zoom Room 5, 12:46 PM

Alzheimer’s disease (AD) is a progressive neurodegenerative disease that is projected to affect almost 14 million American adults by the year 2050. While the prevalence of this detrimental disease is rapidly increasing in the United States, researchers have established the key pathologies connected to AD, including the development of extracellular, amyloid beta (Aβ) plaques, and intracellular, hyperphosphorylated, neurofibrillary tau tangles. Overall, AD engenders general atrophy of the brain and damage to key brain regions including the cerebral cortex and hippocampus, the main brain region responsible for the neural mechanisms of learning and memory. AD pathologies develop in these regions, which commonly results in neuronal death. The presence of AD pathologies, such as Aβ, activates microglial cells in the brain. Glial cells are the most common brain cells that provide support to neurons. Microglia specifically serve as resident immune cells in the brain, clearing cellular debris, such as dead neurons. Therefore, microglia play a key role in the progression of several neurodegenerative diseases. The activation of microglial cells results in an increased secretion of effector proteins, known as pro-inflammatory cytokines. These are released when inflammatory agents, such as Aβ, are present in the brain. Microglial cells commonly produce pro-inflammatory cytokines, such as TNF-α. Although microglial activation is advantageous at first, continual activation of microglial cells results in a constant inflammatory state. Chronic inflammation can lead to detrimental tissue damage that plays a vital role in neurodegeneration. Another key AD pathology, oxidative stress, is connected to chronic inflammation. Oxidative stress develops when the antioxidant system is unbalanced, resulting in the accumulation of reactive oxygen species (ROS). The presence of inflammatory agents and ROS have the potential to activate microglial cells. Accordingly, our lab utilizes microglial cells to study the harmful effects of inflammation on the brain. Dr. Kayla Green’s lab in the TCU Chemistry Department has successfully created compounds that act as potent antioxidants, L2 and L4. We collaborate with Dr. Green’s lab to research the possible rescue effects of L2 and L4 against inflammation in immortalized, BV2 microglial cells. In our lab’s previous research, we have demonstrated that both L2 and L4 have the capacity to rescue BV2 cells and increase cell survival during oxidative stress. Moreover, the main purpose of the current experiment is to further study the effects of these compounds against key AD pathologies, to understand their therapeutic potential against inflammation in vitro. In the current experiments, we utilized lipopolysaccharide (LPS), an element from the cell wall of gram-negative bacteria, to induce an inflammatory response in BV2 cells. First, we determined several timepoints and concentrations in which LPS treatment successfully induced the secretion of TNF-alpha. Next, we pre-treated cells with the compound, L4, for one hour prior to LPS treatment, to study the possible rescue effects of the drug against pro-inflammatory cytokine production. We are currently determining which concentration of L4 is the most therapeutic against pro-inflammatory cytokine production in BV2 cells.

View Presentation

BIOL2021BRYANT58318 BIOL

THE EFFECTS OF EARLY LIFE STAGE THYROID DISRUPTION ON REPRODUCTIVE BEHAVIORS IN FATHEAD MINNOWS (PIMEPHALES PROMELAS)

Type: Graduate
Author(s): Austin Bryant Biology Marlo Jeffries Biology
Advisor(s): Marlo Jeffries Biology
Location: Zoom Room 4, 01:02 PM

Changes in thyroid hormones levels have been associated with alterations in somatic development and growth. However, recent studies have shown that alterations in thyroid hormone levels during early life stage (ELS) development can lead to long-term changes in reproduction. Specifically, fathead minnows that have been exposed to propylthiouracil (PTU) experienced a 50% reduction in fecundity. The purpose of this study was to determine if ELS thyroid disruption led to an alteration of reproductive behaviors in male fathead minnows. To accomplish this, larval fathead minnows were exposed to PTU and reproductive behaviors were quantified. Results showed that PTU-exposed fish demonstrated significantly fewer reproductive behaviors than those in the control group. This data provides an explanation for the previously observed 50% decrease in fecundity in the fathead minnows exposed to PTU and provides further evidence that ELS thyroid disruption can interfere with the display of key and ecologically-relevant behaviors later in life.

View Presentation

BIOL2021CLARE38450 BIOL

Comparative genomics of rainbow trout (Oncorhynchus mykiss): are genes associated with migration conserved among populations?

Type: Graduate
Author(s): Catherine Clare Biology
Advisor(s): Matthew Hale Biology
Location: Zoom Room 1, 01:26 PM

The rainbow trout, Oncorhynchus mykiss, is a partially migratory organism, that has been used recently to study the genetic control of migration. Much of this research has taken place at a unique site in Sashin Creek, Alaska, where the resident O. mykiss population is completely isolated from the migratory population. However, it is unknown the extent to which findings here are shared with other populations. Here we used a fine-scale genome-wide sequencing approach known as pooled sequencing to gather genetic data from 174 fish in two locations – Sashin Creek, Alaska and Little Sheep Creek, Oregon. Four sequenced pools were developed based on phenotype and population. We then measured differentiation between the populations to identify regions that may be correlated with the resident or migratory phenotype in both populations. We were able to locate 8 genes in 16 regions of shared elevated FST, and 17 genes over 16 regions with a significant Tajima’s D value that were specific to either the migratory or resident phenotype. These findings indicate specific genes and chromosomal regions that may be important in the regulation of migratory tendency in this species.

View Presentation

BIOL2021HEMBROUGH51002 BIOL

Shoreline Spiders as Sentinels of Mercury Contamination of the Trinity River

Type: Undergraduate
Author(s): Michael Hembrough Biology Matt Chumchael Biology Ray Drenner Biology Simon Gaul Biology Maddy Hannappel Biology Ian Rolfe Biology
Advisor(s): Ray Drenner Biology Matt Chumchal Biology
Location: Zoom Room 2, 12:54 PM

Mercury (Hg) is found in the environment in excess of historic baselines throughout the globe because of widespread atmospheric emissions of inorganic mercury (IHg) from anthropogenic sources such as coal-fired power plants and artisanal gold mines. In aquatic ecosystems, Ihg deposited from the atmosphere is converted by bacteria to methylmercury (MeHg), a bioavailable neurotoxin that adversely affects the health of vertebrates including humans and wildlife. Because IHg deposition varies across the landscape, it is necessary to monitor MeHg levels in aquatic food webs of individual waterbodies. This is a challenge because there are millions of river miles and lakes in the U.S. Shoreline spiders that feed on MeHg-contaminated emergent aquatic insects have been proposed as sentinel species to monitor MeHg contamination. Sentinel species are species which serve to map the bioavailable fraction of pollution in an ecosystem by retaining the pollutants in their tissue. The objective of this study was to test the hypothesis that shoreline spiders can be used as sentinels to evaluate MeHg contamination of river food webs. Our study focused on the Clear and West forks of the Trinity River. A pilot study in 2016 indicated the two forks have different levels of MeHg contamination. From June to August 2019, we collected over 1000 long-jawed orb weaver spiders (Tetragnathidae) along the shorelines of the two forks of the river. Spiders were preserved in 95% ethanol and sorted by leg length into different size categories. Mercury was analyzed using direct Hg analysis. Concentrations of Hg in spiders increased with spider size and was higher in the Clear Fork than the West Fork. A follow up study confirmed that fish in the Clear Fork had higher concentrations of MeHg than in the West Fork. This is one of the first studies to demonstrate that shoreline spiders can be used as sentinels of MeHg contamination in river ecosystems.

View Presentation

BIOL2021JAMES26632 BIOL

Use of DNA Barcoding to Distinguish Between Morphologically Similar Red Bats

Type: Undergraduate
Author(s): Jacob James Biology
Advisor(s): Amanda Hale Biology Dean Williams Biology
Location: Zoom Room 6, 01:58 PM

Across North America, bats are being killed in large numbers at wind energy facilities and there is concern that this level of mortality threatens bat populations. Currently three species of migratory tree bats, including two Lasiurus species, comprise ~75% of all known fatalities; however, as wind energy development expands into new areas (e.g., the southwestern U.S.) there is the potential for new species to be impacted. Ongoing work in our labs has indicated that that our current understanding of the distribution of Lasiurus species across North America is limited, at best, and that more species are impacted by wind energy development than previously thought. Accurate knowledge about which species are being impacted where, and to what extent, will greatly improve the implementation of effective mitigation strategies. We obtained 19 bat fecal samples from wild-caught Lasiurus bats from a study being conducted at Texas State University to improve the species-specific effectiveness of an ultrasonic acoustic deterrent (UAD) at deterring bats from approaching operational wind turbines. Based on morphology, these wild-caught bats were identified as eastern red bats (L. borealis), but it is possible that some of the individuals were western red bats (L. blossevillii). We extracted DNA from the bat fecal samples and amplified the COI mitochondrial gene to determine the correct species identification for each sample. The final sequencing reactions are underway, and the results will be available soon. These data will improve the accuracy of the results from the flight cage study at Texas State University and will contribute to improving strategies to reduce bat fatalities at wind energy facilities.

View Presentation

BIOL2021JOYCE51871 BIOL

Assessing Genetic Diversity in Northern Yellow Bats Killed at Wind Energy Facilities

Type: Undergraduate
Author(s): Jack Joyce Biology
Advisor(s): Amanda Hale Biology Dean Williams Biology
Location: Zoom Room 6, 02:39 PM

Although wind energy facilities are a growing source of renewable, clean energy, they have been shown to contribute to increasing bat mortalities which could threaten the persistence of bat populations. This study aims to expand what we know about the biology and behavior of bat species impacted by wind energy development. Recent research has indicated that yellow bats (Lasiurus spp) are killed at wind energy facilities in the Rio Grande Valley of south Texas. We have limited understanding of the population biology or movement patterns in these species, so the extent to which wind turbine mortality may impact these bats is currently unknown. As part of ongoing research in our labs, I extracted DNA from 18 tissue samples collected from northern yellow bats (Lasiurus intermedius) at a wind energy facility in Willacy county, Texas in 2015. I amplified a region of the mtDNA, the COI locus, and will compare genetic diversity of these samples to a larger data set from wind energy facilities in nearby Starr and Hidalgo Counties that were studied in 2016 and 2017. Together, these datasets will improve our understanding of Lasiurus intermedius genetic diversity and population structure, and have the potential to provide much needed insights into the potential impacts of wind energy development on bats in southern North America.

View Presentation

BIOL2021KANG64747 BIOL

Effects of Pollen Limitation on Seed Production in the Pale Pitcher Plant

Type: Graduate
Author(s): Karis Kang Biology
Advisor(s): John Horner Biology
Location: Zoom Room 5, 02:55 PM

The student hasn't submitted any abstract yet.

View Presentation

BIOL2021LEE9767 BIOL

Investigating the Effects of BRCA1 Construct Length on its Interaction with PALB2

Type: Undergraduate
Author(s): Jaehyun Lee Biology
Advisor(s): Mikaela Stewart Biology
Location: Zoom Room 4, 03:35 PM

Mutations in BReast CAncer 1 protein (BRCA1) play a crucial role in DNA damage control such as double-strand DNA break repair mechanisms. Mutations in BRCA1 increase the chance of disrupted genetic integrity by its contributions to the development of breast cancer. BRCA1 must bind to its partner protein PABL2 (Partner and Localizer to BRCA2) in order to properly carry out its function in the repair mechanism pathway, but its conformation once bound to PALB2 is not clear. In its inactive state, PALB2 is known to remain in an alpha-helical coiled-coil homodimer conformation. Through this observation, we hypothesized that the intrinsically disordered region of BRCA1 on its binding surface will undergo a conformational change into an alpha-helical form. In order to test this hypothesis, we first created a truncated BRCA1, making it 50 amino acids long, then conducted nuclear magnetic resonance (NMR) experiments. Through the NMR experiments, we found that the binding interface of BRCA1 does change its conformation into a helical state, forming a coiled-coil heterodimer upon binding with PALB2.

View Presentation

BIOL2021MARTIN47525 BIOL

ASSESSING THE EFFECTS OF INHERITED MUTATIONS ON PALB2 STRUCTURE AND FUNCTION

Type: Undergraduate
Author(s): Davis Martin Biology
Advisor(s): Mikaela Stewart Biology
Location: Zoom Room 6, 01:50 PM

The proper functioning of the protein PALB2 is vital to preventing tumor formation within breast tissues in individuals. Upon the detection of DNA damage, PALB2 and BRCA1 bind to each other along with BRCA2 to form a DNA repair complex. This complex then repairs DNA double-strand breaks in order to prevent the accumulation of DNA damage that leads to breast cancer. While both BRCA1 and BRCA2 have been extensively studied, a lot of information about the structure and function of PALB2 remains unknown. It is thought that BRCA1 and PALB2 bind via PALB2’s coiled-coil domain; however, how variants of unknown significance (VUS) affect this binding interaction is largely unknown. Further, while some of these VUS have been studied in vivo, cheaper and easier in vitro methods to measure their effect on binding affinity have yet to be formulated. Thus, we hypothesized that isothermal titration calorimetry (ITC) could be used as an in vitro testing method for assessing the effects of VUS within the coiled-coil domain of PALB2 on the binding event between PALB2 and BRCA1. Further, we hypothesized that a decrease in binding between the two proteins as measured by ITC would correlate with a decrease in DNA repair as measured in vivo. We tested the efficacy of this method by creating seven mutations within the coiled-coil domain of PALB2 and measuring the binding event of PALB2 to BRCA1 via ITC. Our results strongly suggest that the binding event is enthalpic in nature and can be adequately measured via ITC as evidenced by the correlation between our in vitro data and previous in vivo data.

View Presentation

BIOL2021MIELCUSZNY31700 BIOL

Evaluating sex-specific differences in cellular immune function in a small fish model, the fathead minnow

Type: Undergraduate
Author(s): Andrew Mielcuszny Biology
Advisor(s): Marlo Jeffries Biology
Location: Zoom Room 3, 02:47 PM

Evaluating sex-specific differences in cellular immune function in a small fish model, the fathead minnow

Andrew Mielcuszny
Department of Biology

Advisor: Dr. Marlo Jeffries

Previous studies in the Jeffries lab have shown that male and female fathead minnows differ in their ability to fight and survive bacterial infections. Specifically, males have significantly higher rates of mortality upon infection than females. Despite this, few studies have sought to identify the sex-specific differences in specific immune processes that underlie the observed differences in survival following pathogen infection. The purpose of this study was to examine the sex-specific differences in phagocytic cell activity, a key innate immune response in which immune cells engulf and destroy pathogens. To evaluate phagocytic cell activity, kidney cells were isolated from male and female adult fathead minnows and their ability to phagocytose fluorescently-labeled E. coli was measured. The relative phagocytic cell activity of male and female fathead minnows will be presented in an effort to explain whether differences in phagocytosis contribute to differences in pathogen resistance.

View Presentation

BIOL2021ROLFE47714 BIOL

Shoreline Spiders as Sentinels of Mercury Contamination of the Trinity River

Type: Undergraduate
Author(s): Ian Rolfe Biology Michael Hembrough Biology
Advisor(s): Ray Drenner Biology Matt Chumchal Biology
Location: Zoom Room 4, 03:03 PM

Mercury (Hg) is found in the environment in excess of historic baselines throughout the globe because of widespread atmospheric emissions of inorganic mercury (IHg) from anthropogenic sources such as coal-fired power plants and artisanal gold mines. In aquatic ecosystems, Ihg deposited from the atmosphere is converted by bacteria to methylmercury (MeHg), a bioavailable neurotoxin that adversely affects the health of vertebrates including humans and wildlife. Because IHg deposition varies across the landscape, it is necessary to monitor MeHg levels in aquatic food webs of individual waterbodies. This is a challenge because there are millions of river miles and lakes in the U.S. Shoreline spiders that feed on MeHg-contaminated emergent aquatic insects have been proposed as sentinel species to monitor MeHg contamination. Sentinel species are species which serve to map the bioavailable fraction of pollution in an ecosystem by retaining the pollutants in their tissue. The objective of this study was to test the hypothesis that shoreline spiders can be used as sentinels to evaluate MeHg contamination of river food webs. Our study focused on the Clear and West forks of the Trinity River. A pilot study in 2016 indicated the two forks have different levels of MeHg contamination. From June to August 2019, we collected over 1000 long-jawed orb weaver spiders (Tetragnathidae) along the shorelines of the two forks of the river. Spiders were preserved in 95% ethanol and sorted by leg length into different size categories. Mercury was analyzed using direct Hg analysis. Concentrations of Hg in spiders increased with spider size and was higher in the Clear Fork than the West Fork. A follow up study confirmed that fish in the Clear Fork had higher concentrations of MeHg than in the West Fork. This is one of the first studies to demonstrate that shoreline spiders can be used as sentinels of MeHg contamination in river ecosystems.

View Presentation

BIOL2021RYAN2552 BIOL

An assessment of potential river otter habitat in the Dallas/Fort Worth Metroplex

Type: Graduate
Author(s): Patrick Ryan Biology
Advisor(s): Esayas Gebremichael Geological Sciences
Location: Zoom Room 1, 12:38 PM

For this project, I mapped potential river otter habitat in the Dallas/Fort Worth metroplex based on literature data on known river otter habitat preferences in Texas. I will use this data along with GIS data on land use/cover/vegetation and distance from suitable water bodies, to determine where in the DFW river otters may prefer to live. This project is interesting and informative because in recent years more urban run-ins with river otters have been documented in the DFW. So knowing where they might like to be is good information for citizens to have, as river otters continue to make a comeback in numbers in the state of Texas.

(Presentation is private)

BIOL2021SEGALA33133 BIOL

The effects of light availability, prey capture, and their interaction on pitcher plant morphology

Type: Graduate
Author(s): Michael Segala Biology John Horner Biology
Advisor(s): John Horner Biology
Location: Zoom Room 5, 02:31 PM

Carnivorous plants inhabit nutrient-poor environments and supplement nutrient acquisition by capturing and digesting insect prey. Carnivorous adaptations have been hypothesized to be beneficial only in environments with high water and light availability. We hypothesized that plant morphology would change in response to resource availability, exhibiting traits that increase carnivory when light is abundant and exhibiting traits that increase photosynthesis when light is limited. In a field manipulation in Leon County, Texas, we examined the effects of feeding, shading, and their interaction on the morphology of the pitcher plant, Sarracenia alata. We employed a two-factor, cross-classified design, with shading (two levels, shaded and unshaded) and prey capture (two levels, fed and unfed) as factors. Eighty plants were haphazardly assigned to one of four treatments: (1) unshaded and fed (control); (2) shaded and fed; (3) unshaded and unfed; and (4) shaded and unfed. When light availability was reduced, plants produced pitchers that had smaller diameters, which is reflective of a photosynthetic morphology. Unfed plants exhibited reduced growth (produced fewer pitchers and had lower sum of pitcher heights). There was a significant interaction effect on estimated seasonal aboveground biomass: shading had no effect on the mass of unfed plants, but shading reduced the mass of fed plants. As the season progressed, competing vegetation reduced light availability to all pitchers. Plants in all treatments began to produce pitchers that were blade-like with a small, non-functional opening and a widened keel. This morphology would maximize light capture at the expense of prey capture. This experiment provides support for a theoretical model that suggests that carnivorous traits are only beneficial under conditions of high light availability. It also emphasizes the importance of periodic burns of carnivorous plant bogs to remove vegetation, thereby reducing light competition.

View Presentation

BIOL2020CALLAGHAN17688 BIOL

Discovering Novel Genes that Allow Bacillus anthracis to Survive Host Defenses

Type: Undergraduate
Author(s): Lauren Callaghan Biology Taylor Kelly Biology
Advisor(s): Shauna McGillivray Biology

Bacillus anthracis is a bacterium that causes the deadly disease anthrax and has been used in bioterrorism. We are looking to investigate what genes within the chromosomal DNA contribute to the virulence of Bacillus anthracis. In this study, we screened a transposon library of B. anthracis ‘knock-out’ mutants for susceptibility to reactive oxygen species used by the immune system. A broad in vitro hydrogen peroxide screen was performed on 1,953 transposon mutants, and after several rounds of in vitro screening, 40 mutants were identified as consistently attenuated in the presence of hydrogen peroxide. Four of these mutants were then tested in the invertebrate model, Galleria mellonella, to assess virulence in an animal model. Mutants with phenotypes that repeated in both assays were prioritized for characterization. The location of the transposon insertion in one of the mutants was successfully identified. Identifying these novel genes contributing to the bacterium’s virulence will provide a better understanding of B. anthracis pathogenesis and may provide potential targets for combatting anthrax.

(Presentation is private)

BIOL2020ELLIS7230 BIOL

The role of SigM and GlpF on cell wall active antibiotic susceptibility in Bacillus anthracis Sterne

Type: Undergraduate
Author(s): Graham Ellis Biology
Advisor(s): Shauna McGillivray Biology

The bacterium Bacillus anthracis, the causative agent for the disease anthrax, possesses two plasmids that contribute significantly to virulence. Besides plasmids, certain chromosomal genes also contribute. In previous studies, our lab discovered that the chromosomally encoded ClpX gene is essential for virulence in B. anthracis. ClpX is an ATPase that is part of the ClpXP proteasome found in many bacteria. Loss of ClpX in B. anthracis Sterne results in increased susceptibility to cell wall targeting antibiotics like penicillin and daptomycin. However, the mechanism behind ClpX’s role in antibiotic resistance is not understood as it is likely that multiple pathways are affected by the loss of this global protease. We recently conducted a microarray to find which genes are up or down regulated in ClpX compared to wild-type (WT) B. anthracis. 119 genes had disrupted regulation and several of these had been connected to cell-wall active antibiotics like penicillin. In this study, we focused on three of these genes: MsrA, GlpF, and SigM. We confirmed the microarray results and showed that MsrA, GlpF, and SigM gene expression in our ClpX strains significantly differs from the wild-type B. anthracis Sterne via QPCR. Insertional knockout mutants were made for GlpF and SigM to test whether these genes were necessary for antibiotic resistance. We are currently testing these mutants in penicillin and daptomycin to assess their phenotypes. We found that loss of SigM results in increased susceptibility to penicillin and are currently studying the effect of daptomycin on SigM and GlpF. We will test the virulence of both mutants in our invertebrate animal model G. mellonella. This will hopefully provide better understanding on the mechanism behind ClpX’s antibiotic resistance.

View Presentation

BIOL2020FINCH42215 BIOL

Investigating sex-based differences in pathogen resistance and immune responses in the fathead minnow (Pimephales promelas)

Type: Undergraduate
Author(s): Miranda Finch Biology Lynsey Malin Biology Leah Thornton Hampton Biology
Advisor(s): Marlo Jeffries Biology

Studies have shown that males and females differ with regard to their ability to survive pathogen infections. The fathead minnow is a newly developed model for immunotoxicity; however, few studies have compared male and female immune responses following pathogen exposure. The purpose of this study was to examine sex-based differences in pathogen resistance and immune responses following exposure to a pathogen in adult fathead minnows (Pimephales promelas). To accomplish this, fish were bacterially infected with Yersinia ruckeri and the immune system’s ability to respond was monitored. Additionally, genes that are known to be expressed during the immune response initiation were measured quantitatively, providing insight into the molecular effect in minnows. At the whole organism level, male fish were less able to survive pathogen infection relative to female fish. At the tissue level, both male and female pathogen-injected fish had decreased hematocrit percentages compared to the fish injected with a saline solution, but did not differ from each other. At the molecular level, increased gene expression of interleukin 1β was seen in pathogen-injected males compared to pathogen-injected females and both sham-injected sexes, indicating that pathogen-injected males mounted a larger inflammatory response at the molecular level. Taken together, this evidence suggests that the increased mortality observed among males earlier in the exposure to the pathogen may be due to the upregulated inflammatory response rather than the effects of the pathogen itself.

(Presentation is private)

BIOL2020KANG53827 BIOL

Effects of Pollen Limitation on Seed Production in the Pale Pitcher Plant

Type: Graduate
Author(s): Karis Kang Biology John Horner Biology
Advisor(s): John Horner Biology

Pollen transfer among flowers contributes to genetic diversity and the maintenance of plant populations through the production of seeds. Decreased pollen receipt can result in fewer offspring. This is known as pollen limitation. We conducted field and laboratory experiments in a population of Sarracenia alata in Leon County, Texas in 2019 to examine 1) the effect of floral herbivory by the pitcher plant moth, Exyra semicrocea, on pollen availability and 2) the impact of pollen receipt on seed quantity and 3) seed quality. We found that floral herbivory significantly decreased the number and mass of anthers in flowers, and that a high pollen load significantly increased the number of seeds produced compared to low-pollen and control flowers. We found no differences in offspring quality among different pollen treatments based on germination traits. Pollen limitation occurs in S. alata and may pose a conservation risk when paired with other ecological disturbances.

(Presentation is private)

BIOL2020KELLY29623 BIOL

Discovering Novel Genes Important for Survival Against Reactive Oxygen Species in Bacillus anthracis

Type: Undergraduate
Author(s): Taylor Kelly Biology
Advisor(s): Shauna McGillivray Biology

Bacillus anthracis is a gram-positive, spore-forming bacterium and the causative agent of the deadly disease anthrax. The B. anthracis genome consists of chromosomal genes and the pXO1 and pXO2 plasmids that strongly contribute to the bacteria’s deadly nature. While the virulence factors associated with the plasmids have been extensively studied, we believe there are still undiscovered chromosomal genes that may also have important virulence factors. To identify novel chromosomal genes associated with B. anthracis virulence, we screened a transposon mutant library of B. anthracis Sterne strain for increased sensitivity to reactive oxygen species. Reactive oxygen species, such as hydrogen peroxide, have many functions in mammalian immune defenses and wild type B. anthracis is able to subvert this host defense. Sensitivity to reactive oxygen species was tested through in vitro hydrogen peroxide assays and after several rounds of screening, eight mutants were confirmed as susceptible. We next tested whether any of these mutants were attenuated in vivo using our invertebrate animal model, Galleria mellonella and found several mutants with decreased virulence. We are currently working on determining the location of the transposon insertion to find which chromosomal gene is disrupted. This could lead to the discovery of novel B. anthracis virulence genes and eventually possible treatment targets for future anthrax outbreaks and attacks.

(Presentation is private)

BIOL2020LAMANTEER44511 BIOL

Comparison of Swim Performance Assays for Evaluating the Cardiovascular Fitness of Larval Fathead Minnows

Type: Undergraduate
Author(s): Gabriella Lamanteer Biology
Advisor(s): Marlo Jeffries Biology

The swim performance assay is a behavioral assessment used to measure cardiovascular function in fish. Previously, the laminar flow assay (LFA) has been the standard method of assessing swim performance in adult fish to measure their cardiac output. The spinning task assay (STA) is a novel, accessible method of assessing swim performance; however, previous studies have not compared the two methods. Additionally, there is little documentation of swim performance in larval fish, a more sensitive study subject for toxicological research. Therefore, the aim of this research is to compare the swim performance of fish in the LFA to those in the STA to determine which method is better for assessing swim performance in larval fathead minnows (Pimephales promelas). In this study, the percent of fish that fail to swim in the LFA is inversely proportional to the age of the fish, but in the STA, there is no correlation between percent failure and fish age. Results show that as fish increase in size, swim performance in the LFA improves, making it a more representative, predictable assay. Results from the STA indicate that swim performance in fish does not improve with size and performance in the STA is not correlated with performance in the LFA. Ucrit values from the LFA have less variation than those from the STA. The results of this study show that the LFA is a more suitable modality for assessing swim performance in larval fathead minnows.

(Presentation is private)

BIOL2020SCHENK25315 BIOL

Predator-Prey Dynamics in an Urban Forest: Assessment Using Raptor Predation on Prey Mimics

Type: Graduate
Author(s): Amber Schenk Biology Amanda Hale Biology Tom Stevens Biology
Advisor(s): Amanda Hale Biology

Predator-prey dynamics play an integral role in shaping and regulating wildlife communities; however, recent studies have shown a decoupling of these relationships in urbanized areas. Trickle-down effects from the disruption of this trophic interaction have the potential to produce impacts that are far-reaching, altering other critical dynamics within the ecosystem. The purpose of my study was to characterize raptor activity and levels of predation in a large urban forest, the Great Trinity Forest in Dallas, TX. To quantify the extent of urbanization, I used ArcGIS Pro’s (version 2.2.0) image classification wizard with supervised, object-based classification on 50-cm pixel resolution, multi-band remote sensing imagery to estimate the percent of impervious surface. Then, from May to August 2019, I conducted weekly raptor surveys and deployed urethane foam prey mimics (snakes and mice) at 18 survey locations along an urban-to-rural gradient within this forest. In total, I detected 161 raptors representing 8 species throughout the season and found no relationship between raptor activity or diversity and degree of urbanization. Of the 732 prey models deployed, 61 showed signs of being depredated whereas 23 were missing and therefore had an unknown fate. Similar to the raptor results, overall predation on mice and snake models showed no relationship with degree of urbanization. Based on markings on the depredated models and photographs from field cameras, raptors appeared to target the snake mimics with no evidence of predation attempts on mice. And finally, I found no significant relationship between raptor activity and predation on snake models. Collectively, these results suggest either increasing levels of urbanization have no effect on raptor-prey dynamics within the Great Trinity Forest or there is low predatory response from raptors in regard to prey mimics.

View Presentation

BIOL2020TUCKER51048 BIOL

Ectoparasite loads of Texas horned lizards (Phrynosoma cornutum) living in small towns

Type: Graduate
Author(s): Mary Tucker Biology Stephen Mirkin Biology
Advisor(s): Dean Williams Biology

Ectoparasites are a vital but often overlooked part of ecosystem dynamics, which have been shown to be negatively correlated with growth and decreased body condition in various vertebrate species. Texas horned lizards living in natural environments are known to harbor red mites (Acarina sp.), but the impact and density of these mites on lizards living in urban environments is not well known. Using weekly surveys during the summer of 2018, we examined the ectoparasite loads on Texas horned lizards (n = 87) from 11 different sites in Kenedy and Karnes City, Texas. We counted mites and recorded where they were found on the lizard’s body. We also determined the sex, age (juvenile versus adult), and body condition (body weight/SVL) of each captured lizard. We found significant differences in the number of mites between males and females, with males exhibiting heavier parasite loads, and also between different sites within the same town. We found no correlation between body condition and number of mites present. We present the first known research of ectoparasite loads of Texas horned lizards from an urban environment. Although the sample size is small, our data suggest that ectoparasite loads of Texas horned lizards from natural environments have lower mite loads than lizards found in an urban environment. These findings deserve further exploration to see if urban environments play a role in increased parasitism.

View Presentation

BIOL2019BAUGH33867 BIOL

Discovery of a novel iron-acquisition gene in Bacillus anthracis

Type: Undergraduate
Author(s): Sam Baugh Biology Jacob Malmquist Biology
Advisor(s): Shauna McGillivray Biology
Location: Session: 2; 3rd Floor; Table Number: 6

presentation location

As the threat of antimicrobial-resistant infections continues to rise, the need for novel antibiotics grows. Targeting virulence factors in bacterial pathogens is one potential strategy for antibiotic development because inhibiting virulence would decrease the ability of the pathogen to evade the host immune response. This strategy may decrease the development of resistance since the treatment is not directly bactericidal and there is less selective pressure put on the bacteria population. Our goal is to discover new virulence genes in Bacillus anthracis that could potentially be a therapeutic target. Specifically, we are interested in finding genes that allow B. anthracis to acquire iron from the host. For bacterial pathogens, iron is critical for growth and often a limiting nutrient in the host. It has been linked with proper functioning of electron transfer proteins and superoxide dismutase enzymes. In B. anthracis infection, iron is acquired from host hemoglobin through a hemolytic pathway, but the complete mechanism of this is unknown. Approximately 1000 transposon mutants of B. anthracis were screened for the inability to acquire iron from hemoglobin, and five were deficient in acquiring iron from hemoglobin in in vitro assays. Of those five mutant strains, only one (9F12) also exhibited an in vivo phenotype using the wax worm model of infection. The gene disrupted in the 9F12 transposon mutant is the dUTPase/aminopeptidase gene. Our aim in this study is to confirm that the disruption of the dUTPase gene leads to the inability to acquire iron from hemoglobin in B. anthracis. Using targeted mutagenesis, we created an insertional mutant strain to disrupt the dUTPase gene and we are currently testing it, along with WT and 9F12, for the ability to grow in iron-limited conditions with or without hemoglobin. Confirmation of this phenotype will demonstrate that the dUTPASE/aminopeptidase gene is important for iron acquisition from hemoglobin and will support further studies to understand the role of this gene in the virulence of B. anthracis.

View Presentation

BIOL2019BOONE41590 BIOL

Analysis of physical stream qualities of East Canyon Creek to assess the possibility of a Bonneville Cutthroat Trout reintroduction project.

Type: Undergraduate
Author(s): Robert Boone Biology
Advisor(s): Amanda Hale Biology
Location: Session: 2; 2nd Floor; Table Number: 8

presentation location

Aquatic parameters such as increased temperatures and dissolved oxygen levels is critical in determining the survival and ability to thrive of trout species, including the Bonneville cutthroat trout. Bonneville cutthroat trout (Oncorhynchus clarkia Utah), a subspecies of Yellowstone cutthroat trout, originated in the Bonneville Basin and is native to many river basins in Utah, Wyoming, Idaho, and Nevada(Duff 1996). East Canyon Creek is a headwater tributary in the Weber River Basin of northern Utah, and a stream where Bonneville cutthroat trout are native. However, due to the introduction of nonnative trout and multiple causes of habitat quality decline, they no longer occur in the stream. Over the summer of 2018, I participated in data collection which assessed the habitat qualities of East Canyon Creek. This data includes temperature, aquatic, and riparian qualities. Data on the corresponding summer for dissolved oxygen is available as well. When compared to Colorado’s Coldwater Criteria, it appears that the temperatures of East Canyon Creek exceeded the acute (22.1°C) and chronic (17.0°C) upper thermal thresholds for cutthroat trout(Todd et al 2008). When compared to the acute (5.0 mg/L) and chronic (6.0 mg/L) dissolved oxygen minimum concentrations(Null et al 2017), East Canyon Creek’s concentrations appear to have dropped below the identified concentrations. The objective of this paper is to statistically analyze the temperature and dissolved oxygen data on East Canyon Creek from 2018, and determine if a restoration project of Bonneville cutthroat trout in East Canyon Creek would be successful. Through the data analysis, we have found that water temperatures during the summer months have significantly exceeded both acute and chronic upper survival limits, and that dissolved oxygen concentrations are significantly lower than the minimum chronic survival level, indicating that East Canyon Creek is not yet suitable for a successful reintroduction of Bonneville cutthroat trout.

View Presentation