Meeting Abstract
While symbiosis can lead to genetic and morphological changes in the both the host and symbiont, few examples exist in which host developmental transition becomes tightly linked to the symbiosis. Similar to corals, the upside-down jellyfish Cassiopea xamachana establishes a symbiotic partnership with members of the dinoflagellate family Symbiodiniaceae. While both host and symbiont benefit from the interaction to fulfill their nutritional requirements, the jellyfish relies on the symbiont in order to complete its lifecycle. In Cassiopea, the polyp to medusa transition (strobilation) is triggered by the colonization of the host. In order to understand the mechanisms that lead to strobilation in Cassiopea, we used Illumina sequencing to profile the transcriptome of polyps post-colonization and during strobilation. We found genes previously shown to be up-regulated in non-symbiotic jellyfish prior to strobilation were not differentially expressed. A closer examination of these genes showed that while expression levels remain unaltered, in situ hybridization patterns revealed their involvement in Cassiopea strobilation is likely maintained. Further assessment of differentially expressed genes of both host and symbiont revealed additional genes that are involved triggering strobilation. These findings shed light on how symbiosis can lead to evolutionary changes in host gene expression and developmental history.
