Analysis of thyroid hormone receptor structure and function during early zebrafish development

The effects of thyroid hormone on growth and differentiation are mediated by thyroid hormone receptor (TR) proteins in the nucleus of a cell which influence the expression of target genes both in the presence and absence of thyroid hormone. In many vertebrate organisms, one TR gene, TR$alpha,$ is expressed during early periods of embryonic development and is thought to function independent of thyroid hormone. The goal of my research was to examine the structure of the TR$alpha$ gene in zebrafish and the possible functions of this gene in early development by looking at the localization of TR$alpha.$ The functional roles of TR$alpha$ will also be tested by altering the levels of TR$alpha.$ The zebrafish model system used in these studies has many advantages. The ability to obtain large numbers of synchronized embryos which develop outside the mother allows the dissection of spatial and temporal gene expression of TR$alpha$ during development. The ease of injection of synthetic RNA into the 1-cell stage embryo permits overexpression of TR$alpha$ during normal development. Because of the optical clarity of the living zebrafish embryo, stages of early development can be observed by light microscopy, allowing a detailed analysis of the effects of altering the function of endogenous TR$alpha.$ Assuming that the TR$alpha$ in zebrafish is structurally and functionally similar to TR$alpha$ in higher vertebrates, further understanding of the roles of TR$alpha$ in the early development of the zebrafish will provide insight into how TR$alpha$ participate in human disease and development.