The Pacific sand lance, Ammodytes personatus, is an ecologically important forage fish in the Salish Sea. Adult sand lance bury themselves head first into sandy substrates to avoid predation and hibernate in colder winter waters, whereas juveniles remain pelagic and do not burrow until their first winter. Many head-first burrowing species exhibit cranial skeletal adaptations that facilitate substrate penetration, yet the specific skeletal modifications that enable A. personatus to burrow efficiently remain poorly understood. This study investigates how vertebral mineralization patterns change over development and how these changes may contribute to burrowing efficiency. We analyzed over 345 vertebrae of preserved A. personatus from 20-80 mm SL using a Bruker SKYSCAN 1273 micro-CT scanner. Using hydroxyapatite reference phantoms (25% and 75%) to calibrate grayscale intensity values, we quantified vertebral mineral density. We compared mineralization across three vertebral regions (cranial, mid-body, and caudal) and over ontogeny. We hypothesized that cranial vertebrae would be the most mineralized and vertebral mineralization over ontogeny would increase linearly. Contrary to our initial hypothesis, caudal vertebrae were 1.5x more mineralized than those in the mid-body or cranium, but cranial vertebrae were still more mineralized than those in the middle of the body. This suggests that the tail may play a more significant role in burrowing mechanics than we previously assumed. We identified a significant negative correlation between mineralization and body length in both mid-body and caudal vertebrae. Our data show that as these fish grow, their vertebral regions become less mineralized. This pattern challenges our expectation that adults would exhibit greater skeletal reinforcement for burrowing and instead suggests that juvenile sand lance may experience stronger selective pressures for vertebral mineralization or that adults employ alternative physiological or behavioral adaptations for substrate penetration.

Fuels are comprised of thousands of compounds and many compound classes. Olefinic compounds in fuels are known to increase the formation of polyaromatic hydrocarbons (PAHs) and gum formation in engines. The formation of the gums leads to premature engine degradation and lessened fuel efficiency. Various methods, such as molecular bromination, have been developed to detect and analyze these gum-forming olefins. Bromination via molecular bromine has been used in the past, but it has limitations, including high cost and potential environmental harm. As an alternative to bromination, I am using silver-ion solid-phase extraction (SPE) to separate alkenes from other compounds in fuels. Silver ion chromatography selectively retains alkenes, allowing for other compounds to be removed. Selective separation of a compound class will allow me to accurately detect and quantify olefins in fuel. My preliminary results show that olefins can be separated from aromatic compounds, polar compounds, and alkanes with silver ion SPE. I accomplished this by collecting the SPE effluent in measured fractions and analyzing each fraction by gas chromatography mass spectrometry to observe analyte breakthrough. I am developing this method to selectively detect trace olefins in fuels.

All cells have a stochastic component to their gene expression, such that even when in the same environment, there will be cell-to-cell differences in gene expression. Studies of this variability in gene expression dynamics have been limited by technological capabilities for measuring gene expression history with single-cell resolution. We have built a history-dependent integrase recorder of gene expression with single-cell resolution in the model plant Arabidopsis thaliana to study the impact of cell-to-cell gene expression variation in two contexts: development of side or lateral roots (LRD) and root regeneration (RR). The recorder uses integrases, proteins from bacteriophages that mediate permanent, heritable DNA changes based on the presence and orientation of a pair of integrase sites. Fluorescent reporter genes within the target construct allows for expression of fluorescent proteins associated with sequential expression of developmental genes. The recorder allows us to tie the switching to expression of developmental genes by expressing integrases with developmental promoters for genes that guide root differentiation. Utilizing our recorder, we are able to illuminate and evaluate variation in the recorder output among roots growing in different contexts. We hypothesize that regeneration leads to more heterogeneity in gene expression than lateral root development, as the latter has more standardized initial conditions and consistent local cues to constrain transcriptional dynamics. We aim to investigate connections between larger scale anatomical variation and underlying cell-to-cell gene expression heterogeneity. This technology will allow us to further understand the dynamics of gene expression during root development and could unlock new avenues for agricultural research and engineering.