The phyllosphere, the microbiome of the leaf surface, is a highly tractable model system, and is particularly adept for empirical studies on microbial ecological and evolutionary dynamics. One open question is how prior local adaptation on a plant host influences the efficacy of microbial biological control agents. Using an experimental evolution approach, in which changes in populations are measured over multiple passaging events, a naturally occurring, defensive phyllosphere bacteria, Pantoea dispersa, was evolved on tomato seedlings. Preliminary assays found that this bacterium has evolved increasingly negative effects on seedling health, suggesting a potential degradation of protective traits. Over the summer, I will help conduct dose-response assays on tomato seedlings to examine how the defensive ability of P. dispersa against the common plant pathogen, Pseudomonas syringae, has evolved over time. Understanding these ecological-evolutionary dynamics in the plant phyllosphere is critical for the implementation of effective biocontrols.
Neural network models have traditionally been viewed as a black box, with tremendous capabilities in a variety of domains, yet with inexplicable inner workings. Past attempts at analyzing neural networks include analyzing model results and learned weights in an effort to design explainable artificial intelligence, as well as early efforts to determine the full capabilities of neural network models. My project seeks to continue in this tradition by investigating the logic-building aspect of neural network models. More specifically, I aim to investigate whether a novel program synthesis neural network model builds internal logical structure during the course of a simple rule-learning task, and whether the model’s logic-building process shares similarities to humans, demonstrated in biases such as a preference for simplicity or brevity.
The perception of a stimulus is strongly influenced by the background surrounding it. In mammals, this figure-ground perception to identify stimuli from the environment is crucial for survival, such as detecting predators. My project aims to explore the neural mechanisms behind figure-ground perception, especially focusing on the role of vasointestinal peptide positive (VIP) and somatostatin (SOM) interneurons in the primary visual cortex (V1). To explore the mechanism, I will first develop a novel mice behavioral task that can accurately quantify figure-ground modulation. Then, I will use optogenetics to activate or silence VIP and SOM neurons to explore how these perturbations affect mices performance in the task. In doing so, I aim to uncover how VIP-SOM disinhibitory circuit contributes to figure-ground perception.
Mitochondrial dysregulation has emerged as a cause for certain forms of Parkinson’s disease. Investigations of the mechanisms linking mitochondrial function to Parkinson’s have focused on the degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc-DA neurons). Norepinephrine-releasing neurons in the locus coeruleus (LC-NE neurons) rely on mitochondria for their daily activity in healthy individuals and also severely degenerate in Parkinson’s. Both SNc-DA neurons and LC-NE neurons are crucial for maintaining various aspects of wakefulness, but it is unclear whether mitochondrial dysregulation in each neuron population distinctly impacts sleep disturbances characteristic of Parkinson’s. For my project, I will address the hypothesis that mitochondrial dysregulation in LC-NE neurons versus that in SNc-DA neurons will have different effects on sleep in a mouse model, which could provide insight for targeted therapies to improve sleep in patients. Toward this goal, I will study mice using a targeted genetic approach where a key […]
Understanding the genetic basis of organ regeneration remains a central challenge in the field of developmental biology. Teeth are a classic model for organogenesis, since many homologous ectodermal organs (e.g., teeth and hair) follow similar patterns of development and regeneration. Threespine stickleback fish are a powerful model organism for studying tooth regeneration in vertebrates because they possess the ancestral dental phenotype of polyphyodonty, in which teeth are continuously replaced throughout adult life. Past research has shown that Foxc1 regulates Bmp6, a gene important for viability, growth, and tooth patterning in threespine stickleback fish, and maintaining quiescence, a period of rest, in mouse hair follicle stem cells. My project aims to study whether Foxc1a and Foxc1b are required for regulating tooth regeneration in threespine sticklebacks. I hypothesize that Foxc1a and Foxc1b play homologous roles in reestablishing quiescence in fish tooth stem cells as Foxc1 does in past studies of mouse […]
People with high level of nearsightedness will have a 5- to 10-fold chance of developing glaucoma, cataract, and sight-threatening diseases such as retinal detachment later in life. Atropine eye drop is one of the most effective therapies for nearsightedness control. I will conduct a small-scaled randomized controlled trial to understand the impact of eye color on the effectiveness of atropine eye drop. Many studies on atropine have focused on Asian populations, and few studies have compared the effect of atropine between Asians and Europeans, who tend to have much lighter iris color and might respond to the drug differently. A prior animal study has shown that the effect of atropine diminishes quicker in rabbits with lighter iris color but has a more sustained and long-lasting effect on rabbits with darker iris color. Therefore, I aim to investigate if the drug has less therapeutic efficacy on light-irides subjects. and see if […]
This research project examines the rich history and future of midwives of color in the Bay Area through the novel implementation of Science, Technology and Society (STS) frameworks. By defining the midwifery model of care conceived by Bay Area midwives of color as a complex sociotechnical system, the process by which midwives of color have created their models of care can be explored at the intersection of the nation’s capitalistic healthcare system, historic attempts to destroy the knowledge produced by grand midwives in the antebellum period and broader African diaspora, California’s legal history, and the Bay Area’s geographical and political history of social justice activism. This research will implement a holistic STS and social justice approach that recognizes the unequal treatment and distribution of resources of Black midwives and their strength as owners of solutions through the construction of oral histories and archival work. By recognizing the importance of midwives […]
In arthropods and vertebrates, Hox genes determine how an organism develops along the axis running from its head to its tail. Little is known of Hox function outside of these standard animal models, but studies in annelids (segmented worms) suggest that Hox genes not only play a conserved role in embryonic patterning, but are also deployed in ways specific to annelids. For example, hox3 is expressed around the posterior growth zone (PGZ), from which all new segments arise. I hypothesize that hox3 is a stem cell marker in annelids that is necessary for PGZ activity. I will examine this hypothesis with expression analysis and CRISPR mutagenesis of hox3 in Helobdella austinensis, a leech. My proposed research represents one of the first analyses of Hox function in a segmented animal that is not an arthropod or a vertebrate; it thus adds to our understanding of how developmental mechanisms evolved during the […]
My research project is simulating the layered honeycomb material BaCo2(AsO4)2 at low temperature and high applied in-plane magnetic field, since BaCo2(AsO4)2 is theorized by the Kitaev honeycomb model to exhibit Kitaev Quantum Spin Liquid (KQSL) behaviors. Currently, the Kitaev honeycomb model is still a very new theory to explain the quantum spin liquid states, and any simulations that corroborate or contradict the experimental results will be examined within the theoretical framework of this model in order to identify possible inconsistencies between the model and the experimental results. This topic will be part of my senior honors thesis project, which expands the simulation to other candidate materials of Kitaev physics. These simulations will help to provide explanations for the magnetic behaviors of BaCo2(AsO4)2 in experiments, and any discrepancy between simulation and experimental results will be examined to determine whether the discrepancy is the product of holes in the theoretical framework of […]
Currently, most chemotherapy drugs used for cancer treatment target specific upregulated or dysfunctional pathways, rather than specific cancer-driving mutations. This results in adverse side effects or reduced applicability, since the drug can also affect normal pathways of healthy cells. In many tumors, cancer-driving mutations alter amino acid residues into cysteines. Due to cysteine’s unique chemical properties, these mutations are an ideal target for covalently binding molecules. This approach is especially useful in undruggable proteins lacking traditionally targeted binding pockets. In this regard, the Nomura Research Group has applied target-based screening of its cysteine-reactive compound library to identify hit compounds that covalently bind target proteins. In this project, I will express, purify, and screen human proteins with common cancer-driving mutations. Subsequently, I intend to utilize established chemoproteomic platforms to characterize hit features like proteome-wide selectivity and on-target engagement. My project ultimately intends to identify and characterize therapeutically useful chemical compounds targeting […]