Functional approaches to the origin of the bilaterally symmetrical body plan in animal development.
This proposal addresses how morphologically complex animals evolved from simpler-looking animals and the relationship between morphological and molecular complexity. Most animals display obvious features of bilateral symmetry, such as lateral appendages or eyes, however, simpler, 'radially symmetrical' animals that arose early in animal evolution do not display these features. Recent results from the Martindale lab have shown that genes that normally participate in the formation of bilaterally symmetric structures are not only present but expressed in polarized patterns in the 'radially symmetrical' anemone, Nematostella vectensis. These data indicate that 'radially symmetrical' animals are built on a bilaterally symmetrical platform that arose earlier than previously thought. Dr. Martindale proposes experiments to further investigate asymmetric gene expression in Nematostella embryos. He will take advantage of Nematostella's recently sequenced genome and his group's extensive experience in the study of Nematostella embryogenesis. He will determine when asymmetric gene expression first begins, the hierarchy of asymmetric gene activation, and the interactions between genes that leads to asymmetric gene expression. To further determine the generality of these results he proposes to study homologous gene expression in closely related stony coral embryos. Dr. Martindale has a strong track record in training graduate and postdoctoral students from diverse backgrounds and the dissemination of results and reagents to the evolution and development community.
99% of all animal species show clear signs of bilateral symmetry. Cnidarians (e.g. jelly fish, corals, and sea anemones) are the most closely related group of animals to these "bilaterians" and appear radially symmtetrical morphologically. Genomic investigations in the sea anemone Nematostella vectensis have shown that these animals not only posses the genes that are causally involved int he establishment of bilateral symmetry in other animals, but that they are expressed asymmetrically during the developmental period. This work has focussed on using modern molecular labeling techniques in living animals to understand the role of these genes during development and looking for asymmetric morphological distributions and functional properties of cells in the nervous system in these fascinating animals. We have developed techniques and resources that are available to colleagues in the scientific community across the globe. Broader Impacts: This research confirms the value of studying a broad range of differnt kinds of animals in order to understand the current and history of bioogical life on this planet. It uses molecular techniques to "peel back the layers of the onion" to reveal important components of the idea fo biological complexity. This research has trained a number of individuals in important STEM fields and the results have been diseminated in both international scientific meetings and in the popular press.
