碩士 / 國立臺灣海洋大學 / 海洋生物研究所 / 100 / In order to evaluate whether diatoms in the East China Sea were affected by silicon deficiency, we used the expression level of diatom silicon transporter gene (SIT) as a physiological indicator. This approach allowed us to directly detect the silicon environment sensed by a diatom cell in the East China Sea. Samples were collected on board R/V Ocean Researcher I during July 6 - 18, 2010. Works conducted included observations of diatom species composition, collection of diatom SIT sequences, and detections of SIT expression at individual stations. For SIT diversity, 48 homologous sequences were cloned. Based on phylogenetic analysis, we found that SIT sequences varied with hydrological environment, and also varied with dominant species. Many new SIT sequences were observed without an association with taxonomically described species. SIT sequences obtained in the East China Sea were used to design specific primers for Chaetoceros spp. and Skeletonema spp., and SIT expression levels were measured by real-time quantitative reverse transcription polymerase chain reaction. In order to establish a threshold expression level for silicon deficiency, a laboratory culture of Chaetoceros affinis was used in silicate-manipulation experiments. According to changes in growth rate indicated by cell numbers, the SIT mRNA expression on the 7th day was selected as the threshold value at 0.403 mol (mol EFL-1). A comparison with this threshold value revealed that all measured expression levels of Chaetoceros spp. SIT in the East China Sea were lower, which implied that Chaetoceros spp. during July 2010 cruise were not in a status of silicon deficiency. As for Skeletonema spp., spatial variation in SIT expression were consistent with the distribution of this species with reliable signals only appeared at 2 stations in the coastal zone. The significance of this expression pattern needs further clarification.
| Identifer | oai:union.ndltd.org:TW/100NTOU5270010 |
| Date | January 2012 |
| Creators | Chao-Chang Feng, 馮超昶 |
| Contributors | Jeng Chang, 張正 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 63 |
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