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Publication Date

2023-5

First Advisor

Michael J. F. Barresi

Document Type

Honors Project

Degree Name

Bachelor of Arts

Department

Biological Sciences

Keywords

developmental biology, embryonic development, Zebrafish, neural crest cells, forebrain, commissures

Abstract

Neural crest cells (NCCs) are a multipotent, neural progenitor cell type that migrate from the neural tube following its closure. This cell type can differentiate into multiple subtypes, one of which includes cranial neural crest cells (CNCCs). CNCCs have been shown to contribute to the craniofacial skeleton, sensory structures and the meninges of the forebrain. Previously we showed using live cell tracking of a UV photoconvertible line Tg(sox10:nls-eos) with confocal microscopy that some CNCCs migrate anteriorly toward and potentially into the embryonic forebrain. By 19 hpf, CNCCs can be seen reaching the dorsal and ventral rostral clusters of the forebrain, and prefigure commissures. By 22 hpf, the majority of expression of the marker used to track NCCs, sox10, is lost, raising questions about the contribution of CNCCs in forebrain development, and what other cell types CNCCs may be differentiating into. In combination with live-cell tracing, we previously utilized the tfap2a/2c double mutant, which demonstrates a total loss of NCCs, and observed decreased intracommisural distance at 28 hpf and infiltration of neuronal cells into the preoptic space. In order to further interrogate the migratory patterns of NCCs and their role in commissure development, we utilized the Tg(sox10:nls-eos) line on the Multi-View lightsheet, which offers increased visualization capabilities to previous microscopy techniques and the potential to track this cell type past 28 hpf. Attempts to capture NCC migration with this method have led to consistent death of the embryo during the time course, illustrating the need to troubleshoot issues in survivability within the constraints of the necessary mounting conditions. We have also employed a complementary approach to the tfap2a/2c double mutant through targeted ablation of NCCs prior to their migration using the combined GAL4/UAS nitroreductase system. Following ablation, we have demonstrated a decreased presence of NCCs at the midline at 22 hpf. At 24 hpf, we observed a qualitative reduction to the expression of one of the first genes expressed in the forebrain, family zinc finger family 2 (fezf2). By 28 hpf, we observed significant changes to gross morphology, including decreased presence of melanophores and alterations to transgene presentation. Moreover, we observed mispatterning of the anterior commissure and a decreased presence of neuronal cells within the forebrain. Taken together, these findings suggest that NCC loss may impact proper commissure formation as well as patterning of neuronal cell types and the genetic marker fezf2 within the forebrain. Funded by the Nancy Kershaw Tomlinson Memorial Fund.

Rights

©2023 Nalini Oliver. Access limited to the Smith College community and other researchers while on campus. Smith College community members also may access from off-campus using a Smith College log-in. Other off-campus researchers may request a copy through Interlibrary Loan for personal use.

Language

English

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