TITLE: Microbial Symbionts from the Endostyle Region of the Ascidiella aspersa (Sea Squirt) capable of metabolizing iodine?

Tunicates (sea squirt) are filter feeders which process liters of sea water daily. They have a preemptive organelle similar to the vertebrate thyroid called an endostyle. The endostyle has been identified as site for iodine metabolism. Our hypothesis was that microbial symbionts associated with endostyle play a role in iodine metabolism. Using Ascidiella aspersa (sea squirt) as the model, we have identified Endozoicomonas ascidiicola as a dominant symbiont of the endostyle and its surrounding tissues. We have found that the mucus secreted by the endostyle in the bronchial sac has an acidic pH providing a unique microbial environment. Indirect evidence from fluorescent microscopy suggest the Endozoicomons are present in tissue and not in the mucus layer and warrant further investigation.