| Summary: | 碩士 === 國立東華大學 === 海洋生物科技研究所 === 100 === The endosymbiotic relationship between coral hosts of Cnidarian and dinoflagellates of the genus Symbiodinium is critical for the health of coral reef ecosystems. However, the cellular and molecular mechanism of the establishment of endosymbiosis is still unclear. Here, we used the bleached sea anemone (Aiptasia pulchella) and its symbiotic microalgae (clade B Symbiodinium) as the model to study the re-establishment of endosymbiosis. When co-cultured the blenched sea anemone with the free-living Symbiodinium clade B dinoflagellates, the dinoflagellates would entered into the host sea anemone around 1 hour later, and mainly concentrated in the mesentery tissue beneath the actinopharynx tissue. Afterwards, most of the Symbiodinium were re-distributed to the tentacle tissue during 24-48 hr of co-culture. The translocation of Symbiodinium was also confirmed from another experiment which observing the translocation of individual symbiont within in the sea anemone. After 72 hr of co-culture, the dramatic replication of Symbiodinium was observed in the tentacle tissue. When pretreated the Symbiodinium with formalin (10% formaldehyde), it also demonstrated that the pretreated Symbiodinium were also accumulated in the mesentery tissue at the first hour of co-culture. However, these dinoflagellates were completely disappeared at 24 hr post co-culture. These results indicate that (1) the route of Symbiodinium entering host is from mesentery tissue to tentacle tissue, and (2) the mesentery tissue of sea anemone may play a critical role on the cellular recognition during the early stage of endosymbiosis.
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