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.

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.

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.

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.

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.

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.

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.

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.

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.

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.