Circadian rhythms are adaptive biological processes that govern the synchronous timing of biological functions and behaviors with the daily light-dark cycle. These rhythms are crucial for the timed regulation of sleep-wake cycles, metabolism, and hormone release, as well as for maintaining harmonious physiological functioning within the body. Within the mammalian brain, a central pacemaker, the Suprachiasmatic Nucleus (SCN), governs the timing of these circadian rhythms. This area contains a subpopulation of neurons that express and release the neurotransmitter Vasoactive intestinal peptide (VIP). These neurons play a role in synchronizing activity across the entire SCN network. Thus, this project is aimed at better understanding how VIP-neurons change shape throughout the day. Preliminary research in the de la Iglesia lab suggests that these neurons change shape across the day, such that VIP neuron fibers-axons and dendrites- are more branched during the day than the night. These results were obtained through the use of mouse models expressing a red fluorescent protein in the VIP neurons (VIP-TdTomato). The mice were perfused at a range of timepoints, and the samples underwent a tissue clearing protocol so that the entire SCN can be captured in one image. Then the software QuPath was used to train a machine learning algorithm to aid in the identification of VIP neuron fibers based on fluorescence expression. However, the performance of the machine learning algorithm has not been validated. To address this issue, I compared the algorithm-generated segmentations with manual annotations from humans, finding agreement 75.3% of the time in terms of fiber location and 77.4% of the time regarding background. These rather promising results demonstrate the usefulness of the algorithm in aiding the investigation of the entire dataset. This research provides a step towards better understanding the structural organization of the SCN, and thus circadian control of essential physiological processes.

Changes within the body that repeat approximately every 24 hours, called circadian rhythms, are controlled by a central pacemaker in the mammalian brain, the suprachiasmatic nucleus (SCN). Circadian rhythms can synchronize to cues like the light-dark (LD) cycle, allowing them to predict the 24-hour environment. SCN neurons are interconnected and connect to other regions within the brain. Our hypothesis is that SCN neurons have the ability to physically change connections throughout the day and that these changes are essential for it to act as a master clock. I explored this plasticity through the study of vasoactive intestinal peptide (VIP) and polysialylated neural cell adhesion molecules (PSA-NCAM). VIP is a neurotransmitter expressed in a subset of SCN neurons and plays a role in the SCN's ability to respond to light. PSA-NCAM is involved in decreasing cell interactions through facilitating events like cell migration and axon guidance; it is only expressed in areas of the adult brain in which neurons display plasticity in their fiber connectivity. Mice house in a 12 hour:12 hour LD cycle were sacrificed at two times, 12 hours apart. I used immunohistochemistry against VIP and PSA-NCAM to determine the levels of these molecules in the SCN. I found that the expression of VIP is higher 9 hours after lights were turned off (ZT 21) compared to 9 hours after lights were turned on (ZT 9). I found that PSA-NCAM has a higher trend of expression levels at ZT 9 than ZT 21. Although these results are preliminary, we find the implication of the results promising. VIP and PSA-NCAM express in anti-phase; as a negative regulator of cell adhesion, higher levels of PSA-NCAM should correlate with lower levels of VIP. Understanding how mammals keep time is important because circadian rhythms are essential for virtually every aspect of an organism's behavior.

Tornadoes are rare events in the Pacific Northwest and are extremely difficult to predict along the coast, causing much surprise when they do form. After witnessing the destruction and rebuilding of a Port Orchard neighborhood that was ravaged by a F2 tornado in December 2018, I was inspired to explore these uncommon occurrences. For this project, I am investigating the near storm environments of tornadic systems that are generated from cold air outbreaks during the winter months along the coastal Pacific Northwest. This is done by analyzing data from massive tornado datasets, METAR (Aviation Routine Air Report) observations of convective precipitation such as graupel, and piecing together upper air reanalysis data to compare them to weather indexes that have been defined to determine atmospheric instability and can be used to predict extreme weather. The goal is to find patterns that are associated with these tornadic events to create more accurate forecasts and to paint a detailed picture of tornado climatology in the Pacific Northwest. My hope for this project is to shed light onto the factors that are at play for tornadoes, hail, and other severe weather that could potentially save lives.

Iron centers which feature metal ligand multiple bonds can be powerful group transfer agents, for example, terminal Fe-oxo intermediates in soluble methane monooxygenase can perform oxo-atom transfer for the selective oxidation of methane to methanol. Abiologically, ligand constructs which enforce desirable electronic and structural configurations have been shown to enhance group transfer to a range of organic substrates. We developed and studied an iron (Fe) molecular complex with two aminophosphine selenide ligands (Se=PPh₂NTol; Ph=Phenyl, Tol=4-Tolyl) that chelate the metal center via the selenium and nitrogen. The iron complex (FeL₂) was synthesized by a reaction between Fe(HMDS)₂ (HMDS = bis(trimethylsilyl)amide) and the aminophosphine selenide. Characterization shows a tetrahedral, high spin, symmetric compound. We hypothesized that FeL₂ can activate and transfer heteroatoms and explored the reactivity of FeL₂ with oxidants, oxo atom donors, and organic azides. Treatment with iodine (I₂) results in oxidation of the iron center (Fe(II) to Fe(III)) and coordination of the iodide counterion results in structural reorganization to a five-coordinate square pyramidal complex. Reactivity with oxo atom donors shows that either the ligand or Fe center are oxidized, and we identified a µ₂-oxo dimer, which is the first Fe-O-Fe dimer to have selenium in its first coordination sphere. We found that FeL₂ forms Fe-nitrenoid intermediates and can perform nitrene transfer to form diazos or do C-H amination, when treated with aromatic and aliphatic azides, respectively. The presented complexes are characterized by single crystal X-ray diffraction (XRD), Evan’s method, nuclear magnetic resonance (NMR), and Ultraviolet-Visible Spectroscopy (UV-Vis). This research builds upon the knowledge of transition metal complexes for heteroatom transformations.