UC Davis Young Scholars Program

Circadian clocks allow organisms to synchronize their internal processes with environmental cycles. In Arabidopsis thaliana (Arabidopsis), the XAP5 Circadian Timekeeper (XCT) gene plays a critical role in regulating this circadian rhythm, with loss-of-function xct-2 mutants exhibiting a shortened ~22-hour period. To further characterize XCT’s genetic function, Shruthi investigated its interaction with HY5, a key light-responsive transcription factor.

Using luciferase-based circadian assays and genotyping, the researchers found that xct-2 hy5-215 double mutants did not show an intermediate circadian phenotype, but rather mirrored the short-period phenotype of the xct-2 single mutant. This suggests that XCT acts downstream of HY5 in the circadian regulatory pathway.

These findings support a genetic hierarchy where HY5 modulates upstream signaling, while XCT executes a downstream effect on clock pace. Given XCT’s evolutionary conservation, including its human homolog FAM50A, which has been implicated in cancer and developmental disorders, this research strengthens the case for Arabidopsis as a model to explore conserved circadian mechanisms with potential biomedical relevance.

To improve real-time field detection of hazardous air pollutants, Sophie designed a compact thermal desorption device compatible with the HAPSITE system.

By incorporating VOC concentrators such as Tenax TA and Anasorb charcoal, the system captures and preconcentrates trace-level compounds from ambient air. The thermal desorption unit then rapidly heats the sorbents to release VOCs into the analyzer, significantly enhancing sensitivity and enabling efficient, on-site monitoring of volatile organic compounds.

In Dr. Ken Shackel’s Plant Sciences laboratory, Brandon investigated a microtensiometer, used for measuring the water potential inside a tree’s xylem. Using a specialized microelectromechanical system (MEMS) which is impacted by the tree’s internal pressure, the devices provide data which can be graphed to model the tree’s daily fluctuations in water potential, something highly beneficial for water conservation and efficient crop growth.

In rare occurrences, tensiometer readings fluctuate wildly from expected values, despite the tree lacking any change, meaning a mechanical issue with the chip was responsible. In order to investigate any potential physical factors which would impact the water potential measure outputted, Brandon ran a variety of tests on microtensiometers, such as embedding sensors into a branch, in the mating agent used during embedding into a xylem, or submerging them in water. He also manipulated the sensors under a microscope using tweezers to test whether they were susceptible to physical strains exerted on the microchip itself.

Brandon found that while physical strains are able to occur on an embedded microtensiometer, the abnormal fluctuations may not be a result of them. More research is needed in this field.

Last summer, Sarah conducted research in the Bornhorst Lab under the mentorship of Weiyi Sun. The lab explores how food’s structural and chemical properties affect its breakdown during gastric digestion. Past studies have shown that acidity, water content, and structure significantly influence nutrient release and digestion rate. Sarah's project built on this by examining how acidity, moisture, and texture change over time during static in vitro gastric digestion.

Using simulated oral and gastric fluids in a 37 °C shaking water bath, she helped test four structurally distinct foods: jicama and coconut (high in fiber), and cookies and cake (high in fat and starch). These foods were sampled at regular intervals and analyzed using three key methods: titration to measure acidity, oven drying to determine moisture content, and a texture analyzer to assess changes in hardness.

The goal was to understand how different food structures influence breakdown behavior. This insight could guide the development of functional foods tailored to health needs—like high-fiber snacks that slow digestion for blood sugar control or high-starch foods that offer quick energy for athletes. Ultimately, this research supports smarter food design for better health outcomes.

Scott helped research cholesterol last summer during YSP. While cholesterol is essential for many biological functions, excess levels can lead to serious health issues such as atherosclerosis and hypercholesterolemia. Recent studies have identified GPR146, a G-protein coupled receptor in liver cells, as a key regulator of cholesterol production in the body. However, GPR146 is currently classified as an orphan receptor, meaning its natural activating ligand is unknown. Identifying this ligand could unlock new strategies for controlling cholesterol levels. To begin searching for the orphan ligand, he learned that researchers must first understand how metals interact in extracellular environments. He was part of a team helping to track these metals by developing a probe using zinc and zinc-selective integrin binding peptides. These metal responsive peptide probes allow for real time detection of metal fluctuations, which is of special importance in the liver. This research will help to explore whether a complex of C-peptide, copper, and albumin may serve as the natural ligand for GPR146.