This project will investigate the role of a small molecule, retinoic acid, during the embryonic development of a representative of hemichordates; a group of animals closely related to our own phylum, the chordates. Unlike most other molecular signaling pathways, it was thought that retinoic acid signaling was a unique and important innovation of our own phylum. However, recent comparative genome studies have identified all the main components of the pathway in many other animal groups, yet there are currently no functional studies outside of our phylum to determine how this pathway evolved such important roles in vertebrate development. In this project, the major genes involved in the synthesis and reception of retinoic acid at the cellular level will be cloned and investigated and the function(s) manipulated using genetic and developmental tools. It is anticipated that these experiments will reveal that the retinoic acid signaling pathway plays multiple roles in defining the major organizational axes of hemichordate embryos, such as the head to tail or anteroposterior axis, and the front to back or dorsoventral axis. The retinoic acid pathway plays many roles in vertebrate biology and yet some of the details of these functions are poorly understood. These experiments will help clarify how this pathway functions to define the major animal axes during development in a simple animal system. Axis development is one of the most fundamental elements to building animal form and function, and elucidating the mechanistic underpinnings is essential for a better understanding of how animal body plans are assembled following fertilization. This project will train students, including members of groups underrepresented in science, in laboratory research and critical thinking. It will also support an exhibit at the Monterey Bay Aquarium to educate the public about marine ecosystems.
