碩士 / 國立彰化師範大學 / 生物學系 / 91 / This paper reports the physiological change of various developmental stages and the dought-tolerance mechanism due to stress in synchronized Chlorella which under intermittent illumination of 14 hr light and 10 hr darkness. Protein level obviously increased at the beginning of the light period. Cells began to synthesize starch, soluble sugar and sucrose after 8 hours illumination, and accumulate to maximum at the 16th hour of the cell cycle. Cell volume and fresh weight also gradually increased at the same time. Starch, soluble sugar, sucrose and protein evidently decreased during dark period. Cells accumulated putrescine (Put) and spermidine (Spd) level to maximum at the 20th of the cell cycle and began to divide and release autospores.
Chlorella DT species were treated with 30 % PEG water stress (-1.745 MPa) at the 12th of the cell cycle in an attempt to investigate the physiological changes. The results indicated soluble starch synthase (SSS) activity, starch and protein content didn’t show significantly different. But proline, soluble sugar and sucrose, sucrose phosphate synthase (SPS) activity and sucrose synthase (SS, synthesis direction) activity remarkably increased under water stress. Furthermore, sucrose synthase (SS, degradation direction) activity was inhibited under water stress. Water stress would not affect put level but obviously decrease spd level.
In addtion, Chlorella DT and 8b species were treated with water stress (-0.461, -1.135 MPa) and salt stress (112mM, 326mM NaCl) at the 12th of the cell cycle. Starch and protein content of two Chlorella species wouldn’t remarkably change but level of soluble sugar, sucrose and proline increased under stress. Accumulation of sucrose resulted from elevation of SPS and SS (synthesis direction) activity and from decline of SS (degradation direction) activity. Although the level of sucrose elevation was the same under stresses in two Chlorella species, cells of Chlorella DT species synthesized sucrose mainly due to SPS pathway, however, cells of Chlorella 8b species synthesized sucrose mainly due to SPS and SS (synthesis direction) pathways. Intracellular proline level increased under stress in two Chlorella species, but Chlorella DT species proline level increased more than Chlorella 8b species level under extreme salt stress (326 mM NaCl).
In a word, the above results suggested that dought-tolerance mechanisms of two Chlorella species were similar to that of higher plant, which related to accumulate proline and sucrose. Nevertheless, synthesis of polyamines seemed to have no relationship with the dought-tolerance mechanism, but relate to cell division.
| Identifer | oai:union.ndltd.org:TW/091NCUE0112011 |
| Date | January 2003 |
| Creators | Yuting Ko, 柯瑜婷 |
| Contributors | John-Yee Lin, 林忠毅 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 101 |
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