Synapse Formation and the Gut Microbiota in Danio Rerio
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Date
2017
Authors
Goode, Collette Adelle
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
The human nervous system comprises billions of neurons. These cells transmit and receive signals from their neighbors via synapses. During synapse formation, hundreds of proteins localize to form connections between pre- and post-synaptic nerve terminals. Everyday behavioral and cognitive functions depend upon the proper formation and organization of synapses between neurons. Disruptions in synapse formation are known to correlate with neurodevelopmental diseases, including Autism Spectrum Disorder, Down’s syndrome, and Tourette’s syndrome. 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 Autism Spectrum Disorder. The interplay between genetic factors and the gut microbiota underlying common neurodevelopmental disorders remain to be identified. Danio rerio, the zebrafish, is an effective model organism in studying synapse formation. The first aim of this thesis applies immunohistochemistry and confocal microscopy techniques to characterize the distributions of various synaptic proteins in the developing zebrafish brain. The telencephalon was of particular interest, as this brain region is believed to correlate with complex behavior in zebrafish. This analysis found that Synaptotagmin 2b expression progressively increases in the telencephalon over development, possibly correlating with the onset of social behavior. The second aim of this thesis was to apply this descriptive analysis to analyze how the absence of bacteria in germ-free zebrafish affects synapse formation in the zebrafish brain. Using the synaptic markers from the first aim, we found synapse intensity and number to increase in the absence of bacteria, indicating that the gut microbiota controls synapse formation.
Description
50 pages. A thesis presented to the Department of Biology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2017
Keywords
Synapse formation, Neurodevelopmental disorders, Gut microbiota, Zebrafish, Synaptic proteins, Synaptotagmin 2b