Date Approved

2020

Degree Type

Open Access Senior Honors Thesis

Department

Biology

First Advisor

Robert S. Winning

Second Advisor

Aaron Liepman

Third Advisor

Marianne Laporte

Abstract

Proper cell migration is necessary for healthy embryonic development. The EphA4 receptor, when activated, triggers a cell migration response away from the signal molecule ephrin that is displayed by surrounding cells. Little is known about how the EphA4 receptor interacts with the actin cytoskeleton to trigger the migration response. We hypothesize that cofilin is key to downstream actin cytoskeleton regulation by the EphA4 pathway. In this study, we observed cofilin gene expression across several stages of early Xenopus laevis embryonic development by using RT-PCR. We observed cofilin protein presence across those same embryonic stages by using Western Blot. We also tested the phenotypic effect of cofilin knockout on Xenopus embryos by using CRISPR Cas9 to induce a mutation in the cofilin gene. We observed exogastrulation in 46.7% of embryos that were injected with both the Cas9 enzyme and the sgRNA sequence that targets the cofilin gene. This result was significantly higher than what was observed in any control (two-tailed t test, p<0.05). The effect of cofilin knockout was similar to what was observed in previous studies on the effect of EphA4 knockout. Our results are consistent with a role for cofilin in the EphA4 pathway, which is crucial to proper embryonic development of X. laevis.

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