碩士 / 國立東華大學 / 海洋生物研究所 / 106 / Previous studies have indicated that the cell cycle of the in hospite Symbiodinium sp. coincides have circadian rhythm in many way, such as cell motility, morphology, lipid metabolism and photosynthesis, which are driven by the light–dark photoperiod.
Furthermore, in hospite Symbiodinium responded to environmental stress by changing their membrane lipid and fatty acid moiety（FA moiety） compositions, but this phenomenon remains further proof. Further study of the lipid and FA moiety composition of cultured Symbiodinium, could advance our understanding of how the free-living Symbiodinium establish the endosymbiosis with their benthic hosts. We chose three strains of Symbiodinium, clade B, C and E, and analyzed the fluctuation of lipid and fatty acid profiles under 12h light/ 12h dark cycles by using TLC（Thin Layer
Chromatography）and GC/MS（Gas chromatography/ Mass spectrometry）. Results showed that the TAG（ Triacylglyceride ） and SE （ Sterol ester ） of Clade B Symbiodinium accumulated during the light period, and decreased during the dark period. The FA moiety profiles revealed a higher abundance of SFA（Saturated fatty
acid）in the light, and more PUFA（Poly-unsaturated fatty acid）in the dark period. These findings indicated that the lipidome of Clade B Symbiodinium undergoes diel variation. However, the lipidomes of Clade C and E Symbiodinium did not fluctuate significantly. Under the culture condition, Clade B was observed to undergo stable cell cycle suggesting that its lipogenesis was responsive to the diel cycle. Yet, under the same culture conditions the rates of cell cycle of Clade C and E were relatively longer and hence, there was no significant diel variation in lipogenesis in these clades. We speculate that the culture conditions may not have been optimal for clade C and E, i.e., light cycle, cell density, and/or medium. Clade E is mostly free-living and is not prone to symbiosis with Cnidarians. The carbon source utilization of Clade E was different from that of the other clades, with a predominant accumulation of free fatty acids (FFA). Additionally, our data showed that distinct prominent FA moiety constituents in the three clades: Clade B are C16:0, C18:1 n9 and C18:0; Clade C are C18:3 n6 and C22:6 n3; and Clade E are C14:0 and C18:4 n3. Thus, our findings highlight that the
physiological metabolism of the three Symbiodinium clades is profoundly different. The diel variation of the lipidome in cultured Symbiodinium provide the key information to further study the regulation of the symbiotic mechanisms.
| Identifer | oai:union.ndltd.org:TW/106NDHU5277017 |
| Date | January 2018 |
| Creators | Yu-Chun Chang, 張瑜君 |
| Contributors | Chii-Shiarng Chen, 陳啟祥 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 105 |
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