Effect of Season, Body Size, and Sex on the Mercury Concentrations of Orb-Weaving Spiders
Cale Perry, Garrett Helburn, Olivia Eberwein, Madeline Hannappel, Matthew Chumchal, and Ray Drenner
Mercury (Hg) is an anthropogenic contaminants found in all aquatic ecosystems across the world. One of the methods to monitor levels of Hg contamination in an ecosystem is using sentinel organisms: abundant and widely distributed organisms within the food web that accumulate contaminants in body tissues without negative effects. Riparian spiders are a potential sentinel organism for the study of Hg contamination in aquatic ecosystems, as they accumulate mercury through the consumption of contaminated emergent aquatic insects. The present study will examine the effects of spider body size, sex, and season on 2 taxa of orb-weaving spiders [Family Araneidae: Larinioides sp., Metazygia sp.]. 575 orb-weaving spiders were collected from a boat dock on the South side of Eagle Mountain Lake, Texas, USA, from May to September 2019. The spiders were preserved in 95% ethanol and sorted based genera, month collected, sex, and size class. Size class was determined by measuring the spiders front left leg length (tibia + patella) and served as an indicator of body size. Mercury contamination will be analyzed through direct Hg analysis.

Plants with threatened habitats and fragmented populations may require repatriation efforts to maintain healthy populations. Populations of Sarracenia alata, the pale pitcher plant, are severely fragmented, and the species is near threatened. A complete understanding of its reproduction will be crucial in establishing and maintaining healthy populations. The goals of this study were to determine if 1) S. alata is capable of selfing (reproducing with pollen from the same individual); 2) S. alata is capable of autogamy (selfing without intervention); and 3) pollen load affects reproductive success. We used seed set to measure individual fitness. Thus, it was necessary to determine a reliable method of counting seeds. Two methods were examined, and these gave statistically similar results. We found that while S. alata is capable of selfing, it is not autogamous. Seed set was significantly higher in outcrossed individuals than in selfed individuals . In 2019, plants receiving supplemental pollen yielded more seeds than those in either the control group or a group in which pollinator access was restricted. During 2021 (a year with higher pollinator activity), there was no significant difference between the number of seeds produced by control plants and those receiving supplemental pollen. This study demonstrates the important role of pollinators in maintaining healthy populations in this system.

Migration, which is defined as the seasonal movement for survival or reproductive advantage such as access to resources, is a behavioral phenomenon exhibited by many species including the salmonid Oncorhynchus mykiss. More commonly known as rainbow trout, O. mykiss exists in two life histories: migrants (steelhead trout), and residents (rainbow trout). While there are many factors that contribute to this variation in migration behavior, one of the reasons is their genetic makeup since there is an apparent correlation between the migratory behavior of parents and their offspring. The primary objective of this research project is to identify single nucleotide polymorphisms (SNPs), or genetic differences, which are associated with migratory behavior in rainbow trout. To that end, I used whole genome sequence data from five migrant and five resident rainbow trout. These data were aligned to the trout genome and used to locate genetic differences between the two migratory types. Quantitative PCR (DMAS-qPCR) approaches were used to validate the SNPs and genotype them in a larger set of twenty-five migratory steelhead. Research findings exhibited that Sashin Lake is producing smolts (young migratory steelhead) that are successfully returning to the lake and reproducing at the end of their life cycle. Additionally, while there was not a significant difference seen in terms of marine survival between the sexes, females were more likely to migrate compared to their male counterparts due to the reproductive advantage and greater access to resources that migration offers. This data will support future studies observing trout migratory behavior with larger sample sizes and from different generations and settings and will benefit conservation studies regarding population decline in migratory species.

BRCA1 is a gene whose protein (also named BRCA1) is found throughout all human cells and engages in DNA repair, cell cycle regulation, gene transcription regulation, and apoptosis. However, mutations in BRCA1 typically confer a higher risk of cancer in estrogen-responsive tissues, including breast epithelial tissue. This increase in incidence of tissue-specific cancers is thought to be in part due to the role of BRCA1 in the estrogen response pathway and interaction with the estrogen receptor alpha (ERα). Previous studies identified possible regions of each protein involved in the binding interface between BRCA1 and ERα. Using these regions (amino acids 177-240 in BRCA1 and the ligand binding domain of ERα) as our constructs, our studies further analyzed the molecular details of this direct interaction and determined methods conducive to studying the BRCA1-ERα interaction. A pull down assay qualitatively confirmed binding between the constructs of BRCA1 and ERα. Data collected from NMR spectroscopy reaffirmed the direct interaction between BRCA1 and ERα first seen in the pull down assay and provided evidence demonstrating that the presence of estrogen in the samples increased binding affinity. Finally, fluorescence spectroscopy of quenching experiments confirmed the previous two results – that a direct interaction between the constructs of BRCA1 and ERα used occurs and the binding affinity increases in the presence of estrogen – and allowed us to describe the binding curve of the system being studied. The molecular details confirmed here provide further avenues of study, such as documenting variants of unknown significance or studying the role estrogen plays in the function of the BRCA1-ERα complex, which could lead to novel findings that expand our understanding of the role either protein plays in cancer development.

Alzheimer’s disease (AD) affects about 6 million Americans, and hallmark pathologies of AD include amyloid beta (Aβ), inflammation, and oxidative stress. Microglial cells (MGCs) are brain cells that function like immune cells, and they respond to Aβ by secreting pro-inflammatory cytokines. Cytokines induce inflammation at sites of infection, and Aβ continually increases inflammation, resulting in neuronal death. Inflammation is also connected to oxidative stress, and prior research has demonstrated that Nrf2 (a transcription factor) protects cells from oxidative stress by increasing antioxidant enzymes. We will test potential benefits of molecules with antioxidant capabilities, created by Dr. Green (TCU Chemistry), on inflammation and Nrf2 expression in MGCs. Previously, we demonstrated that these compounds, L2 and L4, are powerful antioxidants that protect MGCs from oxidative stress. Currently, we aim to study the effects of L2 and L4 on inflammation, Nrf2 expression and heme oxygenase-1 (antioxidant) production following an inflammatory insult. We will pre-treat MGCs with different concentrations of L2 and L4, and then stimulate MGCs with lipopolysaccharide (LPS), a bacterial mimetic. Subsequently, we will measure pro-inflammatory cytokines, Nrf2 expression and antioxidant response genes. Overall, it is crucial for researchers to investigate effective therapeutics that could relieve AD symptoms, such as antioxidant treatment.