Tag: Alexandra Tallafuss

Presenter: Collette Goode

Faculty Mentor: Philip Washbourne, Alexandra Tallafuss

Presentation Type: Poster 64

Primary Research Area: Science

Major: Biology

The central nervous system depends on the appropriate formation of synapses between neurons to enable communication throughout neural circuits, which generates behavioral and cognitive functions. Recent studies have shown that some individuals with Autism Spectrum Disorder (ASD) have an abnormal composition of the bacterial community resident, referred to as microbiota, within their intestine. Studies in mice suggest that the microbiota can signal to the developing brain, indicating that changes in the intestinal microbiota may underlie some of the deficits seen in ASD. We began to test this hypothesis by using zebrafish as a model to learn how the microbiota affect synapse formation. We used immunohistochemistry and confocal microscopy to compare synaptic protein distribution in the brains of conventional and germ-free zebrafish. We focused on the forebrain, which is speculated to correlate with complex behavior in zebrafish. We labeled the pre-synaptic proteins SV2 and Synapsin1/2 to allow us to image and quantify synapse density in the telencephalon of germ-free and conventional zebrafish larvae at 6 days post-fertilization. We found a significant increase in the number of synapses expressing Synapsin1/2, but no difference in synapses expressing SV2 in germ-free compared to conventionalized zebrafish. Further study of synapse density, function and behavior of germ-free fish will promote our understanding of the correlation between the microbiome, synapse formation, and prevalent neurodevelopmental disorders.

Presenter(s): Allison Hoslett

Faculty Mentor(s): Alexandra Tallafuss & Phil Washbourne

Poster 71

Session: Sciences

Research for neurodevelopmental disorders characterized by social deficits, such as Autism Spectrum Disorder, has helped increase the quality of life in individuals and families afflicted by these diagnoses. This research aims to understand the neuronal network underlying social behavior in the developing brains of zebrafish (Danio rerio), an experimental animal model that shares relevant cellular pathways and social behaviors that are conserved between vertebrate animals. The neuronal circuit involved in social behavior is poorly understood. We are using genetic and behavioral research techniques to identify populations of neurons that are necessary to recognize biological motion, an important part of social behavior. We are combining behavioral assays and genetic tools that allow for cell tracking and targeted cell death using the nitroreductase/metronidazole system. After targeted ablation of neurons in different areas of the brain, we measure the social behavior of individual zebrafish larvae. We do this by projecting dots that imitate the presence and movement of another fish, tracking the fish’s reaction with these dots, which is then calculated into a social index. We were able to identify neuronal populations that, after ablation, severely reduce social behavior. Using this approach will allow us to identify a more complete picture of how the social circuit works and which neuronal populations are involved. Unraveling the social circuit will allow early identification and more targeted treatment of patients with neurodevelopmental disorders that are characterized by impairments in typical social behaviors.