Biocontrol Evolution in Tomato Seedlings

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.

...Read More about Luyang Zhang

Analyzing Neural Networks in the Context of Concept Learning Tasks

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.

...Read More about Mellon Zhang
Rose Hills

VIP-SOM Disinhibitory Circuit in V1 during Figure-Ground Perception

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.

...Read More about Xiaozhou Zhang
L&S Sciences

The Impact of Mitochondrial Dysregulation in LC-NE Neurons on Sleep

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 […]

...Read More about Yufan Zhang
L&S Sciences

Functional Genetic Analysis of Foxc1 on Tooth Regeneration

  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 […]

...Read More about Emily Zhao
L&S Sciences