Date of Award

8-2023

Document Type

Thesis

Degree Name

Master of Science in Biology

Department

Biology

First Reader/Committee Chair

Chao, Michael

Abstract

Dopamine (DA) is a neurotransmitter with imperative implications in many functions including movement, reward, and cognition. Studying the pathways of dopaminergic neurons at multiple levels allows us to understand the ways in which these systems can go wrong. We study dopamine in a model system such as the worm Caenorhabditis elegans because of its relatively simple and well-characterized nervous system. DA is involved in regulating chemosensory behaviors in worms. The purpose of this research project is to definitively answer the following question: Are the dopamine receptors DOP-1 and DOP-4 expressed in chemosensory neurons? Previous reporter assays show that neither of these receptors are located in these neurons of interest, although behavioral assays involving knockouts of the genes encoding these receptors show behavioral deficits. Classic transgenic techniques, such as those used originally to visualize the locations of dopamine receptors, involved injecting exogenous plasmid DNA containing promoter-reporter gene fusions into worm gonads to be expressed in offspring. However, these reporter constructs may exhibit different expression patterns than endogenous genes. By using CRISPR/Cas9 to target the dop-1 gene encoding the DOP-1 receptor, the coding sequence for a reporter gene was inserted to visualize where exactly this gene is expressed in its native chromosomal context, with specific attention to neurons involved in chemosensory behavior. While we were able to insert our reporter at the dop-1 locus, fluorescence was not detected. Future work may build on our constructs to examine where this gene is being expressed.

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