碩士 / 國立臺灣大學 / 漁業科學研究所 / 95 / The suitability of using mcy genes analysis for screening toxic Microcystis populations and the release of microcystins were determined. Seven characteristic segments, mcyA~E, J, and the promoter of the microcystin synthetase gene cluster, designed in a Q-PCR amplification were applied for the quantitative measurement of toxic populations in environmental samples. Observations during the method-development experiments against 8 toxic and 4 non-toxic clones of Microcystis were: (i) the expected specific amplicons were found in all toxic clones but absent or less amount in non-toxic clones; (ii) all the toxic clones showed consistent Tm values of mcyD, implying this partial mcyD segment to be the most conserved one among tested mcys; (iii) a linear correlation was obtained between the microscopically determined cell numbers and the PCR threshold cycles; (iv) cell concentration of the toxic Microcystis from Q-PCR measurement was not affected by field sample and the addendum of non-toxic populations. Q-PCR is sensitivity and provides an efficient technology suitable for toxic Microcystis population screening.
Microcystins are considered primary intracellular and microcystins release was generally considered to be linked to a decrease in the integrity of the cells. However, from a strain of M. aeruginosa designated as M.TY-1, it was found that microcystins are released during the log phase of growth and continuously accumulated in the cell-free medium. A single amino acid difference of the sequence McyH was found in the toxin-releasing strain in comparison with other non-toxin-releasing strains. Sequence of McyH was known to be homologous to the bacteria ABC transporter, but also known as a key protein that maintained the integrity of microcystin synthetase clusters. This significant toxin release strain would be a model for the research of the M. aeruginosa toxin release system.
| Identifer | oai:union.ndltd.org:TW/095NTU05451015 |
| Date | January 2007 |
| Creators | Jian-Zhi Lin, 林健智 |
| Contributors | 周宏農 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 92 |
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