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

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

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

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

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

Cryptococcus neoformans is a pathogenic fungus that can cause cryptococcosis, affecting the lungs and central nervous system with potentially morbid consequences. This pathogen is particularly aggressive in individuals with impaired T-cell function, such as those with AIDS or on immunosuppressive medications. There are currently no vaccines available for this pathogen and a limited arsenal of antifungals is available. Our lab has developed a C. neoformans strain that produces mouse IFN-ɣ, called H99ɣ, that induces protective immunity against subsequent infection with wild-type C. neoformans in mouse models of cryptococcosis. We aim to use variants of this strain to better understand the immune response against Cryptococcus and develop new therapies. In this study, our goal is to evaluate the efficacy of various newly developed C. neoformans vaccine mutants to induce protective immune responses against C. neoformans. RNA will be isolated from tissues extracted from mice immunized with the different C. neoformans strains: H99ɣ, LW10, LW10ɣ, sre1ΔLW10ɣ, and sgl1ΔLW10ɣ and the mRNA transcripts of immune cells responding to subsequent infection with C. neoformans evaluated. By using the information derived from these transcripts, we aim to identify key determinants of protection against cryptococcosis. Using the transcriptomic data, we can determine the best candidate to further evaluate for its capacity to elicit protective immune responses in immune-compromised hosts.

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a growing health concern, affecting nearly 24% of U.S. adults. It is characterized by excessive fat accumulation in the liver, often linked to obesity, insulin resistance, and poor dietary habits. Chronic inflammation and oxidative stress play key roles in disease progression, with excessive saturated fat intake exacerbating liver damage. Genes involved in lipid metabolism, such as sterol regulatory element-binding protein 1 (Srebp1c) and peroxisome proliferator-activated receptor γ (Pparγ), regulate fat storage in the liver and contribute to MAFLD development. Additionally, oxidative stress-related genes like nuclear factor erythroid 2-related factor 2 (Nrf2) and glutathione peroxidase 1 (GPX1) influence antioxidant defenses, impacting liver health. Our study investigates the effects of two dietary models—the Typical American Diet (TAD) and the Mediterranean Diet (MED)—on liver health. The TAD, high in saturated fats, promotes lipid accumulation and oxidative stress, while the MED, rich in unsaturated fats, may improve liver function by reducing inflammation and oxidative damage. Findings suggest that diet influences gene expression, affecting lipid metabolism and oxidative stress pathways. Understanding these mechanisms may help develop dietary strategies for MAFLD prevention, emphasizing the role of nutrition in liver health.

Partner and Localizer of BRCA2 (PALB2) is a necessary linker protein between BRCA1 and BRCA2. In order to create this connection it interacts directly with BRCA1 via a coiled-coil domain in both proteins. Facilitating this linkage directs cells to fix double stranded DNA breaks (DSBs) through homologous recombination. The mutation L35P has been shown to disrupt this linkage forcing the cell to complete repair through alternate pathways that are not as accurate. This inaccuracy can lead to the accumulation of mutations and increase the risk of breast and ovarian cancers. The L35P variant within the coiled-coil domain of PALB2 has been linked with hereditary breast and ovarian cancer. However, it is unknown if loss of leucine in the interface is causing the decrease in binding or if it is the introduction of a proline into the coiled-coil region that is destroying the secondary structure thereby inhibiting binding. We are studying five variants of unknown significance (VUS) from PALB2 that are within the coiled-coil and are also proline substitutions. One of these mutations is within the binding interface and the other four are on the backside of the coil. We are investigating the structure and BRCA1-interaction of these VUS to directly connect structural changes in the coil to functional deficiencies. Currently we have found that these proline variants are inhibiting binding with BRCA1 through measuring heat exchange with isothermal titration calorimetry. We also plan on evaluating these variants through circular dichroism as well to assess if the secondary structure of PALB2 is affected as well.

Malesia is a vast phytogeographic region in Southeast Asia, spanning roughly one-fifth of the world’s circumference and considered one of the most biodiverse regions of the world. It is divided into three subregions: Sahul, Sunda, and Wallacea, primarily distinguished by their geological history and differences in floristic composition. Research based on fossil-calibrated phylogenetic trees has begun to provide insights into the historical phytogeography of Malesia, specifically regarding the reciprocal migration of plant lineages across the Sunda and Sahul regions known as the “Sunda-Sahul floristic exchange (SSFE).” This study aims to test the SSFE hypothesis with the use of the Asian tropical blueberry clade of tribe Vaccinieae (Ericaceae). Silica-dried specimens from previous fieldwork, garden-grown plants of wild origin, and herbarium specimens were used to extract genomic DNA. The samples were sequenced with the Angiosperms353 bait set, and a dated phylogenomic tree was constructed, incorporating all available genomic data from online repositories. Divergence time analysis and ancestral area reconstruction was performed to test the hypotheses of the SSFE. This research will serve as a steppingstone towards resolving the phylogeny and evolutionary history of tribe Vaccinieae. It will also form a foundation for assessing the conservation status of micro-endemic and threatened Asian tropical blueberry species, especially in Malesia. Lastly, this study will highlight the crucial role of botanical gardens and herbaria as vital repositories of natural history collections.

Zebra mussels (Dreissena polymorpha) are an invasive bivalve of significant ecological and economic importance due to their widespread invasion and disruption of aquatic ecosystems and commercial infrastructure. Their ability to spread from the northern Great Lakes to the southern areas of the United States is due in large by their reproductive strategy. Zebra mussels release eggs and sperm into the water column where fertilization and subsequent larval development occurs. Two key steps in the fertilization process are the ability of sperm to bind and penetrate the egg surface and the ability of the egg to prevent more than one sperm from entering the egg (polyspermy). In many other species, proteases play a key role in these processes; however, there is there is variability between aquatic species, such that elucidating specific mechanisms is unique to individual organisms. Here, I investigate the potential role of proteases in sperm binding and entry. To discern these mechanisms in zebra mussels, I exposed fertilization processes to small-molecule inhibitors. Based on the observations of the phenotypic changes upon exposure, implications can be made to specific molecules or groups of molecules involved in Dreissena polymorpha sperm-egg interactions. These implications point to the further investigation and development of small-molecule inhibitors of Dreissena polymorpha fertilization.