The causative agent of malaria, Plasmodium spp., generated 608,000 deaths worldwide in 2022 according to the World Health Organization and disproportionately threatens endemic areas of Africa. Plasmodium sporozoites infect the host by entering the bloodstream through the skin following bites by female Anopheles mosquitoes. From there, sporozoites migrate to the liver and infect hepatocytes. A single sporozoite-infected hepatocyte is capable of producing thousands of merozoites, which go on to enter the bloodstream. Complete elimination of infected hepatocytes is necessary to achieve sterile protection. In order to observe adaptive and innate immune cell localization towards infected hepatocytes, we applied fluorescence microscopy on livers in a BALB/c rodent model of malaria. Naïve unvaccinated mice were infected with sporozoites of Plasmodium yoelii, a rodent malaria parasite. Two important cell populations are recruited to infected hepatocytes. The first are tissue resident memory CD8+ T cells (Trm), which are crucial in pre-erythrocytic protection. The second are Kupffer cells, which are specialized liver macrophages. To measure these adaptive and innate cell populations, respectively, we applied fluorescently-labeled antibodies to mark the parasite as well as Trms and Kupffer cells. After staining the collected liver tissue and imaging with a widefield fluorescent microscope, we visualized recruitment and measured immune cell proximity quantitatively within a region of interest of the area surrounding infected hepatocytes using microscopy imaging analysis software. This method will be used to test the hypothesis that Trms and Kupffer cells are induced following sporozoite challenge in the rodent malaria model.

Sambucus newtoni is a type of elderberry (Adoxaceae, Angiospermae) from the late Eocene epoch. It has not received much research attention since its discovery in the early 20th century. Researchers identify it based on its leaflets (parts of compound leaves), with other traits inferred from more modern Sambucus species. As a result, its flower morphology has remained unknown. Here, I contribute to our understanding of S. newtoni by describing an excellently preserved compression fossil of a floret (small flower) from a S. newtoni cluster of florets, a so-called cyme. The fossil was collected from lake deposits in the Florissant Formation, Colorado. I described and analyzed the specimen with a microscope and observed extremely well-preserved petals and anthers (male flower parts). The flower sits next to a fossilized fly specimen on the adjacent sedimentary rock layer. The close similarities of the flower of S. newtoni to that of the extant species S. javanica (Chinese elder) may help confirm recent common ancestry as originally suggested through comparisons of the leaflets. Further, improved understanding of S. newtoni through study of the new specimen may open the door to greater understanding of Sambucus evolutionary history as a whole.

Phytoliths are silica bodies inside and around plant cell which hold crucial evolutionary insights into the grass family, Poaceae. This study focuses on phytolith morphology within the PACMAD group, consisting of the Poaceae subfamilies Panicoideae, Arundinoideae, Chloridoideae, Micrairoideae, Aristidoideae, and Danthonioideae. By examining over 1,500 phytoliths across 114 extant species within these subfamilies, we aim to identify patterns in the distribution and abundance of specific phytolith morphologies, so-called morphotypes. This analysis could help deepen our understanding of both phytolith morphotypes as potential indicators of evolutionary relationships within grasses. We can also use these patterns to determine the taxonomic affinities of fossil phytoliths, which allows us to trace the evolutionary history of grasses in the fossil record. Additionally, we focus on the evolution of C4 photosynthesis, a key adaptation in grasses to dry and hot climates; specifically, how we can use phytolith morphology as an indicator for this evolutionary trait in the fossil record. Through comparative analyses within and beyond the PACMAD clade, we aim to compare phytoliths from modern C3 and C4 grasses to gain a better understanding of the differences between phytoliths from grasses with the two photosynthetic pathways and apply it to fossil phytoliths to better understand when C4 grasses evolved and spread. Furthermore, we emphasize the significance of this research in the context of climate change. By linking phytolith morphotypes to the climatic preferences of extant grasses and applying this information to the fossil record, we can trace past climatic shifts and patterns, learning how grasses adapted to environmental changes. Our preliminary results so far show that there are distinct patterns in phytolith morphology across PACMADs, although, at the genus and species level, there is an overlap in morphological traits that we hope to address with increased data.

Land plants have evolved the ability to uptake silicon from the soil and deposit it as silica-based structures called phytoliths in their tissues. Phytoliths are hypothesized to play a variety of roles in plants including contributing to structural support, defense against abiotic stressors such as drought, and herbivore deterrence. Grasses (Family Poaceae) in particular are known for their high silica concentrations of up to 40% of dry mass. We are investigating whether or not high silica concentrations are more common in grassland species and are associated with C4 photosynthesis. This directly tests the “C4-grazer hypothesis,” which states that, compared to other species, C4 grasses (i.e., those with adaptations allowing more efficient photosynthesis under hot and dry conditions relative to the ancestral C3 photosynthesis) have evolved increased silica accumulation as a response to ungulate herbivory in grassland environments. Using material from herbariums across the world, we have prepared 482 grass leaf samples for analysis. Our samples derive from approximately 200 species from all 12 subfamilies of Poaceae. These samples are analyzed using a portable X-ray fluorescence spectrometer to measure silicon concentration, which serves as a proxy for accumulated silica. To do so, we have established a custom calibration and protocol for measurements. Preliminary results show that high silica concentrations have evolved in a range of grasses, including species occupying both open grasslands and shady forest habitats, and both C3 and C4. This suggests that the mechanisms and influences on silica accumulation may depend not only on photosynthetic pathway and herbivory pressure, but may also depend on other evolutionary and environmental factors. Overall, this research will improve our understanding of how grasses adapt to stressors that will worsen under climate change, and how grasses might contribute to global carbon-silicon cycling.

As the climate changes, we are beginning to see the impacts on a global scale. In order to understand how our landscapes will change with future warming, we can look back to see how landscapes were impacted by past warm, variable climates. This project looks to understand how climate variability in the Middle Miocene is expressed in terrestrial sedimentary records. Using X-ray fluorescence (XRF) analysis, we created a high-resolution elemental geochemical profile of sediment samples from Clarkia, ID (~16 Ma). From XRF, elemental concentrations for a host of elements, including Ca, Fe, K, Mn, Sr, Ti, Zn, and Zr, were calculated. Some elements, notably Ca, showed long-term trends but also sections of shorter-term cyclic variability. It is possible that this variability reflects changes in basin weathering rates of Ca-bearing minerals as a function of climate change occurring on timescales of tens to hundreds of thousands of years. Alternatively, Ca concentrations may reflect changes to precipitation of Ca-bearing minerals within the ancient lake, responding to algal productivity. These hypotheses are tested using X-ray diffraction (XRD) to identify minerals and their crystalline structures as well as characterizing the elemental trends from an additional site, Clarkia’s P-40. Understanding the depositional history of the Clarkia lakebeds aids our understanding in how climate impacts Miocene landscapes.

The latest Eocene Florissant Formation (deposited ~34 million years ago) contains a rich flora and fauna that has received much study by paleobotanists since the 19th century. However, several questions about the ecology and evolution of biota are outstanding and much material remains to be studied. Using observations from a high-definition compound microscope, dichotomous keys, and published literature, I seek to directly analyze and identify an unidentified fossil of a latest Eocene angiosperm, gain a comprehensive view of their surrounding habitat, and contribute to a better understanding of plant-pollinator relationships in the Florissant region. The fossilized angiosperm flower I am studying was collected by Judge Junius Henderson from lacustrine deposits of the Florissant Formation (in modern day Teller County, Colorado). It is a compression fossil with perfectly preserved petals and anthers, providing a rare opportunity for detailed analysis of its anatomy. The rock additionally contains the abdominal region of an insect, which I will attempt to place taxonomically to draw inferences about its ecological role in the Florissant ecosystem. My preliminary studies suggest that the fossil flower belongs to the extinct species Phenanthera petalifera (family unknown)- originally described by Theodore Cockerell in the early 20th century- due to matching dimensions, spatulate appendages, and two-lobed stamens exerted beyond the calyx. The insect is harder to place due to incomplete preservation, but anatomy suggests Aeschneta larvata, a bee fly (family bombyliidae), or a similar insect in order Diptera; I will explore the prominence of these possibilities. Documenting the diversity of plants and potential pollinators in ancient ecosystems existing during past warm climates is crucial for understanding how plant-pollinator relationships might change as anthropogenic warming causes shifts and losses in plant-pollinator niches.