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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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CHEM2021AGUIAR5885 CHEM

Optimizing the Synthesis of Macrocycles

Type: Undergraduate
Author(s): Isabella Aguiar Biology
Advisor(s): Eric Simanek Chemistry & Biochemistry
Location: Zoom Room 3, 01:42 PM

In recent years, macrocycles have emerged to be potential drug leads, as they show to have promise for targeting disease pathways, however their synthesis is quite difficult and has yet to be optimized. Utilizing glycine specifically in macrocycle synthesis was the objective, and this was done by stepwise reactions of successfully adding compounds onto glycine to prepare for cyclization. Cyanuric chloride, BOC-hydrazine, and morpholine were successfully added to glycine, as proven with thin layer chromatography and NMR. However, problems that arose came with purifying the compound for cyclization due to solubility issues. Many attempts utilized column chromatography, but there seems to be promise in utilizing an extraction to purify the compound and prepare for cyclization.

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CHEM2021CRUZBARRIOS15423 CHEM

Determination of Critical Micelle Concentration from Diffusion-Driven Dilution of Micellar Aqueous Mixtures

Type: Graduate
Author(s): Eliandreina Cruz Barrios Chemistry & Biochemistry Onofrio Annunziata Chemistry & Biochemistry
Advisor(s): Onofrio Annunziata Chemistry & Biochemistry
Location: Zoom Room 3, 12:54 PM

Micellization is a phenomenon of central importance in surfactant solutions. Here, we demonstrate that the diffusion-based spreading of the free boundary between a micellar aqueous solution and pure water yields a one-dimensional spatial profile of surfactant concentration that can be used to identify the critical micelle concentration, here denoted as C*. This can be achieved because dilution of micelles into water leads to their dissociation at a well-defined position along the concentration profile and an abrupt increase in diffusion coefficient. Rayleigh interferometry was successfully employed to determine C* values for three well-known surfactants in water at 25 ºC: Triton X-100 (TX-100), Sodium Dodecyl Sulfate (SDS), and Polyoxyethylene(4)Lauryl Ether (Brij-30). The dependence of C* on salt concentration was also characterized for TX-100 in the presence of Na2SO4, NaCl, and NaSCN. Accurate values of C* can be directly identified by visual inspection of the corresponding concentration-gradient profiles. To apply the method of least squares to experimental concentration profiles, a mathematical expression was derived from Fick’s law and the pseudo-phase separation model of micellization with the inclusion of appropriate modifications. While Rayleigh interferometry was employed in our experiments, this approach can be extended to any experimental technique that yields one-dimensional profiles of surfactant concentration. Moreover, diffusion-driven surfactant disaggregation is precise, non-invasive, requires single-sample preparation, and applies to both non-ionic and ionic surfactants. Thus, this work provides the foundation of diffusion-driven dilution methods, thereby representing a valuable addition to existing techniques for the determination of C*.

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CHEM2021EDWARDS17380 CHEM

SQUARAINE DYES AS ENVIRONMENT-SENSITIVE PROBES WITH MULTIPLEXING ABILITIES

Type: Undergraduate
Author(s): Lauren Edwards Chemistry & Biochemistry Luca Ceresa Physics & Astronomy Jose Chavez Physics & Astronomy Sergei Dzyuba Chemistry & Biochemistry Zygmunt Gryczynski Physics & Astronomy Daniel Ta Chemistry & Biochemistry
Advisor(s): Sergei Dzyuba Chemistry & Biochemistry
Location: Zoom Room 5, 03:19 PM

Organic dyes with photophysical properties affected by alterations in the properties of the media, including viscosity, temperature, and polarity, are known as environment-sensitive probes. These probes are widely used in various areas of analytical, biological and material sciences. This poster will describe our initial efforts on designing multi-responsive environment-sensitive probes based on squaric acid scaffolds. Specifically, the incorporation of aminoquinoline moieties produced small molecule viscometers, which have the ability to sense polarity variations of organic solvents. Multiplexing abilities, coupled with modular and facile synthesis, distinguishes these probes from other types.

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CHEM2021FREIRE63707 CHEM

Hydrogen Peroxide Disproportionation with Manganese Macrocyclic Complexes of Cyclen and Pyclen

Type: Graduate
Author(s): David Freire Chemistry & Biochemistry Debora Beeri Chemistry & Biochemistry Kristof Pota Chemistry & Biochemistry
Advisor(s): Kayla Green Chemistry & Biochemistry Benjamin Sherman Chemistry & Biochemistry
Location: Zoom Room 6, 01:34 PM

Oxidative stress is a result of an imbalance between reactive oxygen species (ROS) and the availability/activity of antioxidants. The catalase family of enzymes mitigate the risk from ROS by facilitating the disproportionation of hydrogen peroxide into molecular oxygen and water. Manganese containing catalase (MnCAT) consists of a binuclear manganese core bridged by carboxylate and single-atom ligands, likely water or hydroxide. In this work, hydrogen peroxide disproportionation using complexes of manganese with cyclen and pyclen were investigated due to the spectroscopic similarities of the latter with the native MnCAT enzyme. Potentiometric titrations were used to construct speciation curves to identify what complex compositions were present at different pH values. Based on these results, the complexes were made in situ by mixing stock solutions of ligand, buffer, and metal. The hydrogen peroxide disproportionation reaction was carried out in a sealed cell and PO2 measured using a microsensor (Unisense). When hydrogen peroxide was injected into the cell, disproportionation activity of the complexes was evident by (1) appearance of bubbles in solution, and (2) noticeable increase in PO2 as measured by the sensor. Spectroscopic investigation before, during, and after the reaction was used to follow changes in the UV-visible absorption of the complexes to collect information about the structure of the initial catalyst and any possible intermediate. Both, pyclen and cyclen were determined to form a dimeric structure under the reaction conditions used.

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CHEM2021GLOOR37466 CHEM

Synthesis of Isoleucine Based Macrocycles

Type: Undergraduate
Author(s): Camryn Gloor Chemistry & Biochemistry
Advisor(s): Eric Simanek Chemistry & Biochemistry
Location: Zoom Room 3, 02:23 PM

Many drugs today are small molecules and function through a specific binding with their target. This has proved to be efficient, yet the idea of larger macromolecules being used as drugs has grown more popular because of their flexibility. The issue with these larger molecules is that they have been previously difficult to synthesize. The emphasis of the research is to find an efficient way to synthesize macrocycles, reducing purification processes and side products. All reactions are done in solution and column chromatography is used to purify. An important aspect is testing if this cyclization method is possible with all amino acids or if limitations are present based on the backbone of the molecule. Because macrocycles have proved difficult to synthesize in the past, they are overlooked in the field of drug design. However, with this rather basic process it is possible to create new rules associated with drug design and defy what was once believed about macrocycles.

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CHEM2021GUEDEZ50076 CHEM

Genetic selection of sarcosine-specific synthetic riboswitches from a glycine riboswitch

Type: Graduate
Author(s): Andrea Guedez Chemistry & Biochemistry
Advisor(s): Youngha Ryu Chemistry & Biochemistry
Location: Zoom Room 6, 12:38 PM

The aptamer domain of a naturally occurring glycine riboswitches was randomized to generate a library containing billions of different variants. The dual genetic selection of this library was performed for sarcosine, a prostate cancer marker, and successfully led to the identification of sarcosine-specific synthetic riboswitches. When a chloramphenicol-resistance gene was expressed under control of these riboswitches, E. coli cells showed chloramphenicol resistance only in the presence of sarcosine. For a colorimetric assay, the sarcosine riboswitch gene was inserted upstream of the lacZ gene. When tested with various concentrations of sarcosine, the enzymatic activity of LacZ was proportional to the amount of sarcosine, clearly indicating the sarcosine-dependent gene regulation by the sarcosine riboswitch.

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CHEM2021HENDERSON7043 CHEM

DFT Simulations of the pKa Values of Triazines

Type: Graduate
Author(s): Nicholas Henderson Chemistry & Biochemistry
Advisor(s): Benjamin Janesko Chemistry & Biochemistry Eric Simanek Chemistry & Biochemistry
Location: Zoom Room 1, 12:46 PM

Triazines appear in pharmaceuticals, agrochemicals, and as building blocks for polymers used in materials science and medicine. Predicting the structure and dynamics in water as a function of pH requires reliable simulations of the pKa values for different sites for protonation. We present the initial DFT methods and continuum solvent for pKa of amines, ring nitrogens, and 2,4,6-triamino-1,3,5-triazine (melamine) derivatives. These M06-2X/6-311++G(2d,2p) calculations in SMD continuum solvent provide consistent accuracy for tested systems, use for future studies of more complex structures.

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CHEM2021JELINEK6743 CHEM

Synthesis of Organic Macrocycles for Anti-Microbial Testing

Type: Undergraduate
Author(s): Trevon Jelinek Chemistry & Biochemistry
Advisor(s): Eric Simanek Chemistry & Biochemistry Shauna McGillivray Biology
Location: Zoom Room 3, 02:55 PM

Organic synthesis and research into the activity and uses for macrocycle compounds have increased in recent years. These compounds proved to be an interesting field of research due to their size and ability to orient in different ways depending on the environment. The synthesis of these molecules is done by using a stable foundation molecule, cyanuric chloride, which is subject to substitution. The compound can be built from there using nucleophilic substitution with various nitrogen-based compounds. Then, in the final steps of the synthesis, the compounds dimerize forming the macrocycle. The amino acid nucleophile used to build the molecule is being varied to build many different compounds. The challenge, however, is to find the most efficient route for synthesis. I have successfully managed to synthesize one macrocycle compound using lysine with a Z protecting group as the starting material. Throughout the synthesis there was great difficulty with the compound’s solubility, therefore the starting material was switched to a BOC protected lysine amino acid. This resulted in better solubility throughout the process and yielded another successful macrocycle. These results demonstrate how the synthesis pathway we used to build these macrocyclic dimers is successful, but the process can be variable, based on the properties of the amino acid. It is recognized how the synthesis of these compounds is only the first step and further research into the properties and actions of the compounds is necessary. However, a pure product and efficient synthesis in making the macrocycle is important to properly access its properties. My further research will specifically test the antibiotic properties, if any, the macrocycles possess.

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CHEM2021NGUYEN20674 CHEM

Evaluating the therapeutic efficacy of a small indole-containing tetra-aza macrocyclic pyridinophane for treatment of Alzheimer's Disease

Type: Undergraduate
Author(s): Nam Nguyen Chemistry & Biochemistry Kristof Pota Chemistry & Biochemistry
Advisor(s): Kayla Green Chemistry & Biochemistry
Location: Zoom Room 5, 01:10 PM

The mis-regulation of reactive oxygen species (ROS) and transition metals contribute to the onset of Alzheimer’s Disease (AD). A tetra-aza macrocyclic pyridinophane with an indole moiety, (Ind)PyN3, was evaluated on its radical scavenging reactivity and ability to chelate and stabilize the copper (II) oxidation state; these evaluations contribute to the overall therapeutic efficacy of the ligand in treating AD. Compared to a congener replacing the indole moiety with a hydroxyl moiety, (OH)PyN3, (Ind)PyN3 displayed comparable radical scavenging reactivity to (OH)PyN3. The fluorometric CCA assay revealed that (Ind)PyN3 was able to the stabilize the copper (II) oxidation state and prevent it from generating ROS via redox cycling at both 1 and ½ equivalents, albeit (OH)PyN3 was more effective at copper (II) oxidation state stabilization than (Ind)PyN3 at half molar equivalence. Our results demonstrate that the addition of the indole moiety to a tetra-aza macrocyclic pyridinophane does not disrupt radical scavenging reactivity by the indole moiety nor the ability of the pyridinophane to stabilize transition metal ions, warranting future exploration of the indole moiety in therapeutic design for AD.

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CHEM2021POTA8861 CHEM

Manganese Complex of a Rigidified 15-Membered Macrocycle: A Comprehensive Study

Type: Graduate
Author(s): Kristof Pota Chemistry & Biochemistry David Freire Chemistry & Biochemistry
Advisor(s): Kayla Green Chemistry & Biochemistry
Location: Zoom Room 6, 02:15 PM

Owing to the increasing importance of manganese(II) complexes in the field of magnetic resonance imaging (MRI), large efforts have been devoted to find an appropriate ligand for Mn(II) ion encapsulation by providing balance between the seemingly contradictory requirements (i.e., thermodynamic stability and kinetic inertness vs low ligand denticity enabling water molecule(s) to be coordinated in its metal center). Among these ligands, a large number of pyridine or pyridol based open-chain and macrocyclic chelators have been investigated so far. As a next step in the development of these chelators, 15-pyN3O2Ph and its transition metal complexes were synthesized and characterized using established methods. The 15-pyN3O2Ph ligand incorporates both pyridine and ortho-phenylene units to decrease ligand flexibility. The thermodynamic properties, protonation and stability constants, were determined using pH-potentiometry; the solid-state structures of two protonation states of the free ligand and its manganese complex were obtained by single crystal X-ray diffractometry. The results show a seven-coordinate metal center with two water molecules in the first coordination sphere. The longitudinal relaxivity of [Mn(15-pyN3O2Ph)]2+ was found to be 5.16 mM−1 s−1 at 0.49 T (298 K). Furthermore, the r2p value of 11.72 mM−1 s−1 (0.49 T), which is doubled at 1.41 T field, suggests that design of this Mn(II) complex does achieve some characteristics required for contrast imaging. In addition, 17O NMR measurements were performed in order to access the microscopic parameters governing this key feature (e.g., water exchange rate). Finally, manganese complexes of ligands with analogous polyaza macrocyclic scaffold have been investigated as low molecular weight Mn(CAT) mimics. Here, we report the H2O2 disproportionation study of [Mn(15-pyN3O2Ph)]2+ to demonstrate the versatility of this platform as well.

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