Prior research has found that visual cues presented before (pre) or after (retro) an object improve object properties recognition, like identity (what it is) and spatial location (where it is), in humans (Griffin & Nobre, 2003) and monkeys (Brady & Hampton, 2018). However, this has not yet been tested in other species or using other cue modalities (e.g., auditory). The current experiment will analyze the effect of visual and auditory cues on object recognition in 6 pigeons, explicitly examining how these cues influence identity and spatial location processing in a visual working memory task.

Pigeons will perform a change detection task,in a Plexiglas chamber with a monitor, touch screen, and speakers. In each trial, the subject will peck a white crosshair on the center of the screen to start. After 1500 ms, a sample pair of colored circles will appear on the left and right sides of the screen for 5000 ms. After a 1500 ms delay, a test stimulus will be displayed on the screen’s left or right side. Pigeons must compare the test stimulus to the sample previously presented on the same side of the screen. During some trials, pigeons will receive pre- or retro-cue signaling which sample stimulus will be tested (e.g., the one displayed on the left). For half of the pigeons, the cues will be different frequency sounds (auditory group), and for the rest, colored backgrounds (visual group). It is predicted that the auditory group will have higher accuracy than the visual group, suggesting auditory cues may enhance recognition of visual objects more than visual cues.

Invasive plant species significantly impact native ecosystems by outcompeting indigenous flora, reducing biodiversity, and disrupting the delicate ecological equilibrium. In collaboration with the Fort Worth Botanic Garden, this research study evaluated the efficacy of utilizing sheep and goats as a sustainable grazing strategy to mitigate invasive plant species within the garden.

Vegetation analyses, specifically vegetative cover and species richness, of pre- and post-grazing indicated an initial decline in plant species richness. However, based on prior studies, plant succession and resilience are anticipated to rebound in the grazed areas over time (Booth & Skelton, 2009; Rathfon et al., 2021). The research findings also indicated environmental and operational benefits, including reduced labor costs, minimized chemical inputs, decreased noise pollution, and mimicked historical ecological processes that have been found to improve soil health and biodiversity. The findings from this research emphasize the targeted use of livestock grazing as a sustainable land management practice. This case study highlights the benefits of integrating controlled livestock grazing into public garden maintenance protocols. Furthermore, this research contributes to the existing literature regarding sustainable land management and the role of livestock in controlling invasive species and restoring ecosystems.

References

Booth, A. L., & Skelton, N. W. (2009). The use of domestic goats and vinegar as municipal weed control alternatives. Environmental Practice, 11(1), 3-16. DOI:10.1017/S1466046609090012

Rathfon, R. A., Greenler, S. M., & Jenkins, M. A. (2021). Effects of prescribed grazing by goats on non‐native invasive shrubs and native plant species in a mixed‐hardwood forest. Restoration Ecology, 29(4).

https://doi.org/10.1111/rec.13361

Mercury (Hg) emitted in temperate and tropical regions can be transported to the Arctic where it is disproportionately deposited across the landscape. In aquatic systems, inorganic forms of Hg can be methylated to the toxic and bioaccumulative species, methylmercury (MeHg). In temperate zones, riparian spiders that specialize in consuming adult insects emerging from aquatic systems (e.g., Araneidae and Tetragnathidae) accumulate high concentrations of MeHg and have been used as sentinels of MeHg contamination. In addition, these taxa frequently accumulate concentrations of MeHg that may pose a risk to arachnivorous songbirds. Although these taxa are useful sentinels in risk assessment studies in the temperate zone, they are not present in the High Arctic. The purpose of the present study was to assess the potential of a generalist spider species, the Arctic wolf spider (Pardosa glacialis), to serve as a sentinel of Hg pollution in the Arctic. In summer 2022, we collected 1460 wolf spiders and 8090 emergent aquatic insects (Chironomidae) from six ponds in Northwest Greenland (centered around 76.5° N, 68.8° W). Spiders and insects were composited by body size and collection site. Hg concentrations for spiders and insects ranged from 230 - 1100 ng/g dry weight (dw) and 75 - 297 ng/g dw, respectively. Spider Hg concentrations were strongly correlated with insect Hg concentrations (R2 = 0.83), suggesting that wolf spiders can be used as sentinels of Hg contamination in Arctic lentic systems and had Hg concentrations that exceeded risk thresholds for arachnivorous songbirds.

Bacteriophages, the most abundant biological entities on Earth, specifically infect bacteria. These viruses initiate the lytic cycle, hijacking the cellular machinery of their bacterial hosts to replicate, which ultimately leads to the host's destruction. Phage therapy has shown promising results in treating antibiotic-resistant infections, though clinical trials are ongoing to fully establish its safety and efficacy. Identifying suitable phages is crucial in developing successful therapy due to the specificity of bacteriophage-host interactions.
Our study refined methods for isolating and studying bacteriophages against Enterobacter aerogenes, a critical ESKAPE pathogen contributing to antibiotic resistance. We evaluated two isolation techniques: the overnight enrichment assay and direct isolation via the whole plate spotting assay. Our comparison found an advantage of the direct isolation method—it not only matched the efficacy of the overnight enrichment but surpassed it by offering accelerated results and minimizing resource utilization. A key refinement for purification was the incorporation of calcium chloride into the soft agar, which markedly enhanced plaque clarity and visibility. Moreover, our exploration of DNA extraction techniques revealed the superiority of zinc chloride precipitation over commercial kits, with the former delivering higher DNA yield and purity.
We isolated three phages, K-1, BB-1, and M-1, effective against E. aerogenes. Noteworthy, phage BB-1 exhibited a rapid lytic cycle, clearing plates in under 10 hours. Future research will focus on examining their infectivity across Enterobacter strains, lysis of host cells, and absorption rates. We will also analyze their genome sequences to determine their novelty and potential for addressing antibiotic resistance.

The presence of Reactive Oxidative Species (ROS) in the brain have been linked to the etiology of Alzheimer’s disease and neurodegeneration. In this project, novel antioxidant Indole derivative drugs were tested on BV-2 microglial cells using RT-qPCR to assess their ability to activate antioxidant gene expression. Nuclear factor erythroid 2–related factor 2 (Nrf2) is a gene transcription factor that is activated by oxidative stress and binds to a sequence called the Antioxidant Response Element (ARE), a region upstream of the DNA promoter sequence. Nrf2 activates transcription of antioxidative genes. Based on theoretical docking studies, we hypothesize that the novel compounds will disrupt the interaction between Nrf2 and its inhibitor KEAP, releasing Nrf-2 and enabling it to translocate to the nucleus. The novel antioxidant drugs should either increase the transcription of Nrf2-activated genes or reduce overall levels of antioxidative stress within cells. We tested for antioxidant properties by measuring Hemeoxygenase-1 (HO-1) and Nrf2 mRNA levels in BV-2 cells in the presence of these compounds.

Estrogen receptor alpha (ERα) and BRCA1 play an important role in the development of breast cancer, and multiple pathways link these two proteins together. Previous studies have identified the ligand binding domain (LBD) of ERα and residues 1 through 258 of BRCA1 as important in the direct physical interaction between these two proteins. This study aimed to characterize the binding kinetics of this interaction in the presence and absence of 17β-estradiol (estrogen) with a shortened BRCA1 construct (residues 177-258); however, binding between ERα LBD and this BRCA1 construct could not be detected through fluorescence emission spectroscopy or isothermal titration calorimetry (ITC). Synthesizing ERα LBD presented challenges with low yield, so the purification protocol was refined to cool bacterial cultures at an OD600 of 0.2 during growth and add dithiothreitol during lysis for improved yield. A 24% decrease in fluorescence intensity upon addition of estrogen to ERα LBD confirmed the ligand-binding functionality of the protein. Additionally, Stern-Volmer studies verified that the estrogen binding site on ERα LBD is located in close vicinity to the tryptophan residues in the protein since fluorescence quenching was more efficient in the absence of estrogen. Finally, factors contributing to the absence of ERα-BRCA1 binding are discussed, including the length of the BRCA1 construct used or the potential necessity of an additional protein, BARD1.

BRCA1 and PALB2 proteins suppress tumor formation by promoting homologous recombination when DNA damage has occurred. Mutations in BRCA1 and PALB2 are associated with a higher prevalence of breast and ovarian cancers. Phosphorylation of BRCA1 and PALB2 occurs upon DNA damage and is vital for maintaining genomic integrity. The molecular mechanism of how phosphorylation directs the activation of these proteins is unknown. It is established that phosphorylation of BRCA1 and PALB2 occurs in or near the coiled-coil regions of both proteins. The proteins use this domain to heterodimerize, so we hypothesize that the phosphorylation events could promote efficient BRCA1/PALB2 interactions. Our study aims to determine the effect of phosphorylation on the BRCA1/PALB2 binding affinity. The serine and threonine residues that are phosphorylated on BRCA1 or PALB2 were mutated to a glutamic acid to mimic phosphorylation. Glutamic acid carries a negative charge and thus mimics the negative charge added to the protein upon phosphorylation. We overexpressed and purified the protein using a bacterial expression system and measured their heterodimerization affinity with isothermal titration calorimetry (ITC). We will share ITC data suggesting phosphorylation of PALB2 does not affect its binding affinity to BRCA1. The phosophomimicking mutations in BRCA1 have also been generated, both individually and in tandem, and we will share results from these binding studies that are ongoing and hypotheses generated from our results regarding phosphorylation as an activation switch to control BRCA1/PALB2 interactions.

The Identification of Novel Genes Related to Iron Acquisition in Bacillus Anthracis Sterne

Jessica Guilhas, Kyle Gallegos, Julio Manceras, Mariah Green, Jacob Malmquist, Shauna M. McGillivray

Bacillus anthracis, the causative agent of anthrax, is a spore-forming, gram-positive bacterium. Its virulence mechanisms are of interest due to its potential use as a biological weapon and high lethality. For B. anthracis to survive and reproduce in a host, it must evade the host's immune response and acquire nutrients. One important nutrient B. anthracis must acquire is iron. Iron is a limiting nutrient in the host because it is usually found sequestered to hemoglobin or bound to host proteins such as transferrin. To acquire iron, pathogens must strip it from the host proteins. To find genes important for iron acquisition from hemoglobin, we screened genetic mutants created through transposon mutagenesis. Media was chelated to remove all divalent cations, including iron, and then hemoglobin was added as the sole iron source. The mutants that were unable to grow were chosen to be tested in a larger volume hemoglobin assay. We confirmed the phenotype of several mutants using this larger volume assay and we are working to confirm the site of transposon disruption via PCR. The mutants thus identified include a mutation in a dUTPase gene and an L-aspartate oxidase gene, neither of which has been previously linked to iron acquisition from hemoglobin. Future directions include making independent mutations and/or complement the disrupted genes to confirm the gene disruption is linked to loss of iron acquisition from hemoglobin. This study allows for a further understanding of how B. anthracis acquires iron and sheds new light on potentially novel virulence mechanisms.

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by the formation of amyloid beta (Aβ) plaques in the brain and is the seventh leading cause of death in the United States. Chronic inflammation and oxidative stress associated with AD leads to neuronal cell death. A cellular protective mechanism against oxidative stress involves the Nuclear factor erythroid 2-related factor (Nrf2) pathway. Nrf2 is responsive to the reactive oxygen species (ROS) produced when the cell is under oxidative stress, leading to its translocation into the nucleus where it activates transcription of genes that produce antioxidant enzymes like heme oxygenase-1 (HO-1). To study this pathway in neurons, our lab chose to use the mouse hippocampal HT-22 neuronal cell line. Our previous attempts to grow these cells in culture proved difficult, leading us to hypothesize that providing a growth-enhancing surface of collagen would provide a more stable surface in which to propagate these cells. Here we show that HT-22 cells grown on rat tail collagen provide a model system to investigate the Nrf2 pathway. We also demonstrate that HT-22 cells are viable on tissue culture plastics without the need for collagen.

Exploring EncT Efflux Pump Functionality and their Role in Lipid Signaling
Gabby Linares, Sawyer Diaz, Natalia Castro-Lopez, Floyd Wormley Jr.
Department of Biology, Texas Christian University

Cryptococcus neoformans, a fungal pathogen mainly affecting immunocompromised individuals, has sparked interest in lipid signaling research due to its role in pathogenesis. Eicosanoids, derived from fatty acids, are crucial in virulence and immune modulation; with C. neoformans lacking human enzyme homologs for eicosanoids biosynthesis, we want to identify the enzymes involved in the biosynthesis of cryptococcal eicosanoids and test their potential as antifungal targets. This project is focused on the EncT gene, encoding an efflux pump, which we observed to be upregulated in response to lipid precursors. Using CRISPR technology, we produced an EncT knockout (KO) strain and the corresponding reconstituted strain, aiming to discern shifts in virulence factors like melanin production, capsule formation, and urea production, among others, comparing the knockout, wild-type, and reconstituted strains and, subsequently, employing a mouse model of pulmonary cryptococcosis to delve deeper into virulence dynamics. Our initial results show early production of melanin EncT KO compared to the WT strain and no changes in the capsule formation or growth at 37°C.