| Summary: | 碩士 === 國立東華大學 === 海洋生物科技研究所 === 101 === The Cnidarian-Symbiodinium endosymbiosis is an interesting phenomenon in that the microalgae cell, Symbiodinium spp., lives inside an animal cell and plays a critical role of maintaining the health of the host. However the mechanism for establishment of endosymbiosis on the cellular and molecular level is still unclear. Since the symbiodinium has a unique mobility cycle during a 12 hr light/12 hr dark photoperiod cycle, possessing mobility only in G1 stage of the light period, the mobility of Symbiodinium may be a factor for establishing the endosymbiosis within their host. In this study, we used bleached anemone (Aiptasia pulchella) and the free-living Symbiodinium spp. to examine this hypothesis. Since only 30-40% of Symbiodinium have mobility in a culture, for obtaining the population of the Symbiodinium with mobility, we developed and established a culture and collection protocol which could obtain the Symbiodinium with more than 80% having mobility. We then prepared different populations of Symbiodinium with 80%, 40%, 20% and 0% having mobility and co-culture them with bleached anemone respectively to study the effect on re-establishment of endosymbiosis. It revealed that the bleached anemone uptake produced on average, 169.5, 63.8, 18.4 and 8.75 Symbiodinium cells within one hour’s co-culture with the Symbiodninium respective to the 80%, 40%, 20% and 0% of population having mobility. It has been proven that the Symbiodinium could uptake and re-establish endosymbiosis with their host in the non-mobile stage in lab condition which is a high cell density condition. Otherwise, in an open ocean, the cell density of Symbiodinium is really low, thus, in nature the cellular mobility of Symbiodinium is the first and crucial factor in contact and uptake by their host and then re-establishing the endosymbiosis.
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