Invasive plant species can alter ecosystem dynamics through allelopathy, the release of chemical compounds that inhibit neighboring plant growth. This study tests whether Pennisetum setaceum inhibits the germination of two native grasses, Stipa pulchra and Melica californica, through allelopathy. Aqueous extracts were prepared from fountain grass roots, leaves, and seeds at concentrations of 2.5%, 5%, and 10% (w/v). Native seeds were germinated in controlled Petri dish bioassays, and germination was recorded after seven days across multiple trials, with distilled water as the control. Results show that P. setaceum extracts reduced germination in native species, particularly at higher concentrations. Root and leaf extracts exhibited more consistent suppression than seed extracts, with species-specific responses observed between S. pulchra and M. californica. To investigate underlying mechanisms, chemical characterization of extracts using H-NMR spectroscopy is underway to identify potential allelochemicals, particularly phenolic compounds. These findings suggest that allelopathy may contribute to the invasive success of P. setaceum and highlight the importance of considering chemical interactions in the management and restoration of California grassland ecosystems.

Exposure to wood smoke particles (WSP) from wildfires is a significant driver of cardiovascular and pulmonary morbidity and mortality, yet the specific chemical constituents and molecular pathways responsible for this toxicity remain poorly defined. This research investigates the toxicological impacts of WSP, focusing on their electrophilic potential and ability to disrupt cellular homeostasis. This study involves assessing the intrinsic electrophilic potential of WSP through the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity assay, which serves as an effective indicator because the protein's sensitive active site is susceptible to irreversible binding by electrophiles. Our results demonstrate that WSP and HULIS significantly inhibit GAPDH activity by up to 50% +/- 33% and 66% +/- 34%, respectively. The study explores how WSP and its sub-component, Humic-Like Substances (HULIS), induce functional iron deficiency and inflammatory responses in pulmonary cells. To investigate downstream physiological impacts, RAW 264.7 macrophages were exposed to aqueous extracts of WSP and isolated HULIS. By integrating gene expression analysis of iron transport and antioxidant defense with enzymatic assays, this work clarifies how woodsmoke-derived particles trigger systemic oxidative stress. These findings validate the use of GAPDH activity as a predictive biomarker for the toxicological potential of wildfire-derived particulate matter and provide a mechanistic basis for the adverse health outcomes observed in exposed populations.

A central question in developmental biology is how spatiotemporal gene expression programs regulate organogenesis. The Arabidopsis root provides a powerful model for addressing this question due to its simple structure and continuous production of de novo roots. In Arabidopsis, the periodic production of lateral roots is regulated by the root clock, an endogenous oscillator that primes specific cells to become lateral root stem cells. Although root clock activity has long been monitored using time-lapse imaging of DR5:Luciferase, an auxin-responsive transcriptional reporter, this approach lacks cell- and tissue-level resolution, leaving the relevant cell type and transcriptional regulators unresolved. To address this challenge, we used single cell RNA-sequencing to profile roots expressing the DR5:Luciferase reporter. We recovered a total of 21,488 cells from roots treated with either D15, a compound that dampens root clock activity, or a mock control. Luciferase transcripts were enriched in elongation- and maturation-zone cells, with particularly strong signal in inner root cell types. D15 treatment reduced luciferase transcript levels in several elongation-zone cell types. Among these, elongation-zone xylem pole pericycle emerged as a key cell population, with differentially expressed genes under D15 treatment associated with flavonoid biosynthesis and several candidate transcription factors. These results define the cellular context of root clock-related gene expression and identify candidate regulators for future study.

This abstract has been withheld from publication.

This abstract has been withheld from publication.