Analysis of heart morphology in zebrafish mutants with targeted inactivation of the dio2 gene.

Genetic inactivation of the type II deiodinase gene (dio2) involved in thyroid signaling results in hypothyroidism and is associated with developmental defects in zebrafish. Observation of the heart region in this mutant contrasts strongly with that of a wild-type animal, suggesting a cardiac hypertrophy, a hypothesis supported by gene expression and immunological data. To better characterize the morphological differences induced in zebrafish organs, in particular the heart, our aim is to use X-ray phase contrast technology on whole zebrafish to image body with sufficient resolution to obtain a good view of the morphology of the heart in dio2 mutants compared to wild type sibling fishes. Our goal is 1) to observe the heart in an in situ context and measure the volume, shape and position of the heart in these animals, 2) to determine the precise topography (e.g. barycenter analysis) of the organs relative to each other to assess the effects of the mutation on the whole animal.