Mutations in the GDP-fucose synthesis pathway causes vascular instability, swimming and balance defects in zebrafish (Danio rerio)

Fowler, Gerissa (2020) Mutations in the GDP-fucose synthesis pathway causes vascular instability, swimming and balance defects in zebrafish (Danio rerio). Masters thesis, Memorial University of Newfoundland.

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Abstract

The function of GDP-mannose 4,6-dehydratase (gmds) in cerebral vasculature, or general vascular development, of zebrafish has yet to be described. Mutations within the gmds gene can lead to a loss of fucosylation, which is important for a number of cellular functions. In this thesis, it was discovered that a mutation in gmds, resulted in a cerebral hemorrhage, curled tails and abnormal swimming behavior in homozygous mutant zebrafish, created using CRISPR-Cas9. Injections of GDP-fucose and high doses of fucose into gmds mutants rescued the cerebral hemorrhaging phenotype, but neither injection condition prevented the tails from curling. The mural cell marker, foxc1b, which is critical for vascular stability, was significantly downregulated in cerebral vasculature, which was confirmed with qPCR. Crossing the gmds mutants onto an acta2:gfp line revealed significant reduction of smooth muscle actin coverage in cerebral vasculature. A subset of gmds mutants showed a decrease in slc17a8 expression, indicating a failure to orientate themselves in the water column may be attributed to a synaptic transduction defect in the lateral line neuromasts. In addition, acta2:gfp was not expressed in the swim bladder, potentially contributing to the inability to right themselves in the water column.

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