Meeting Abstract
In cnidarian-dinoflagellate endosymbioses, algal symbionts must colonize host tissues and proliferate within cnidarian host cells. Despite the importance of colonization, little is known about the cellular mechanisms that govern the rate of proliferation and pattern of colonization of symbionts through host tissues. To explore these colonization patterns we used the sea anemone Aiptasia and its symbiont partner alga from the family Symbiodiniaceae. To capture symbiont proliferation dynamics within Aiptasia tentacles we used an epifluorescence microscope to rapidly and repeatedly image live Aiptasia and monitor symbiont colonization. We estimated the number of symbionts within each symbiont cell cluster, indicating localized proliferation as opposed to symbiont migration through the gastrodermal tissue or gastrovascular cavity. We also tracked total cluster number, density, and location within tentacles. To determine the effect of temperature stress on colonization dynamics, we inoculated Aiptasia with Breviolum minutum, a homologous symbiont to Aiptasia. We imaged partially colonized anemones for one week and then exposed half of the anemones to a sublethal temperature stress of 32 C. In combination with temperature stress, we further examined colonization processes using heterologous symbiont species and found differences in the rate of symbiont cluster formation, symbiont density, and response to temperature stress. In summary, our results describe the rate of formation and growth of different sized symbiont clusters (singlets, doublets, etc.), and indicate the importance of new cluster growth to colonization. These symbiont colonization patterns will hopefully enable us to better understand processes involved in the initiation of symbiosis and recolonization after periods of dysbiosis.
