What's Got Zebrafish in a Twist? Characterizing twist1b Cis-Regulatory Activity in the Neural Crest of Danio rerio

Undergraduate Honors Thesis

Citations

Citeable URL: https://scholar.colorado.edu/concern/undergraduate_honors_theses/bg257g57f

Abstract

Neural Crest Cells (NCC) and their derivatives form many craniofacial structures unique to vertebrates. These structures allowed vertebrates to transition from filter-feeders to predators and are thought to be some of the main drivers of vertebrates’ evolutionary success. How NCC evolved in ancestral vertebrates remains unclear. However, it is thought that the recruitment of twist genes to the underlying gene-regulatory network (GRN) of the neural plate border (NPB) drove NCC evolution. We hypothesize that mutations in cis-regulatory elements (CREs) of ancestral twist genes may have facilitated their specific expression at the NPB. This study identified and tested two potential CREs of twist1b in a representative vertebrate, Danio rerio (zebrafish), using enhancer detection vectors mediated by tol2 transposon. We also compared the efficiency of two different types of these detection vectors, pGreenE and Twist1b-pGreenE, for resolving enhancer activity in-vivo. Zebrafish transfected with candidate CREs in pGreenE demonstrated low frequencies of twist1b-like expression patterns in neural-crest-derived tissue during early development, while no reporter activity was detected in zebrafish transfected with CREs in the Twist1b-pGreenE vector. These results suggest that the tested CREs may be involved in regulating twist1b expression, specifically in the neural crest. However, future efforts should be oriented towards confirming these CREs' role in the regulation of twist1b.

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