Presenter: Braden Larson, Biology, Russian and Eastern European Studies (REES)
Poster: B-7
Mentor: Charles Kimmel, Institute of Neuroscience
Genes act in concert during animal development to form complex anatomical structures. For example, the jaw skeleton requires precise expression and interaction of a multitude of genes to develop correctly. Our research focuses on the gene endothelin-1 (edn1), which encodes a signaling molecule required for ventral jaw development in the zebrafish, Danio rerio. Because elements of the jaw remain in the edn1 mutant, we hypothesized that other genes function within the edn1 genetic pathway. To test this, we generated double mutant zebrafish, pairing the edn1 mutant allele with mutant alleles of candidate genes based on previous literature. We then analyzed the double mutant skeletons for evidence of genetic interaction, and discovered an enhanced phenotype in one of the double mutants. Specifically, mutants for edn1 and fibroblast growth factor-8a (fgf8a), a gene that encodes another signaling molecule, are missing a portion of their upper jaw, a phenotype not present in either single mutant. To investigate the cell biology behind this phenotype we imaged the cells that constitute the jaw precursor tissue in live transgenic zebrafish. Strikingly, the cells that give rise to this structure appear missing in double mutant fish. Furthermore, we used Fluorescent In Situ Hybridization to observe gene expression of edn1, fgf8a, and potential shared target genes in wild type and mutant embryos. We conclude that cross talk between edn1 and fgf8a signaling is required for development of the jaw skeleton.