A Comparison Between the Genetic Networks Behind Polyp and Medusa Body Plan Development in Podocoryna carnea

Mary Rorick
Pomona College

Because of Cnidarians basal position on the eumetazoan tree, and due to their unique life histories that include a number of very different body plans within a single species, Podocoryna carnea provides a good model through which to study body plan evolution. A comparative approach is taken here to examine whether the molecular mechanisms that have been demonstrated over the past decade to pattern the polyp body plan are also used to pattern the medusa stage. In order to accomplish this comparison, genes coding for conserved transcription factors, including budhead and Cn-NK-2, have been cloned from the Podocoryna carnea genome. These genes are known to play important axis-organizing roles in Hydra (a cnidarian with only a single life history stage) and we have cloned them from the Podocoryna carnea genome. The life history of Podocoryna includes three of the most prevalent cnidarian stages- the polyp, medusa and planula, and thus provides a good model for a comparative study between multiple developmental processes. Through in situ hybridization, the budhead expression pattern has been successfully characterized in the developing polyp, the developing medusa and in both mature life history stages.