碩士 / 輔仁大學 / 生命科學系碩士班 / 93 / Isochrysis gabana had already been studied very well in aquaculture, either in culture condition or in exploring the supplemented values. Isochrysis can synthesize PUFAs which can provide good nutrient staple for aquaculture, and can treat and prevent some human diseases. Heowever, there is not much studies in molecular biology, genomics, and fundtional genomics upto date. For this reason, we study the global expression file of Isochrysis gabana by expressed sequence tags (ESTs). The results of EST analysis can reveal what kind of genes turn on, and how genes regulate the biochemical pathway under specific tissues and environments. Even more we can uncover novel genes. In this study, we constructed two cDNA libraries from two batches of mRNA isolated from Isochrysis gabana growing under two different conditions, cultivating without shaking at room temperature for 39 days and cultivating with shaking at 25℃ for 12 days. The prelimary data of these two cDNA libraries is comprised 695 ESTs, and creates 90 contigs and 412 non-redundant sequences, bringing up to total 502 unique ESTs, after clustering analysis. Furthermore, the numbers of the redundant ESTs are in propotion to the amount cDNAs expressed in Isochrysis gabana by semi-quantitative analysis of RT-PCR. We proceesed NCBI-BLAST and EBI-InterPro to analyzed all the contigs and non-redundant ESTs. There are 92 (18.3％) ESTs have similarity and 410 (81.7％) ESTs have no similarity to the public database. Nine ESTs hit eight kinds of genes of Isochrysis gabana, 48 ESTs hit the genes of algae, and 44 ESTs hit the genes of another species. We have classfied the ESTs with high similarity into nine categories of different functions: ribosomal RNA, photosynthesis, biosynthesis and metabolism, cell structure, gene expression, signal transduction and regulation,defense, transportation, and unknow function. The most abundant expressed genes in this study are related to biosynthesis, metabolism, and gene expression. In addiation, we also found some extraordinary genes such as the gene encoding low-CO2 inducible protein, that only found in marine algae’s chloplast lumen. However, we found quiet a few genes involving fatty acid biosynthesis and metabolism, four ESTs only. The most abundant genes related with fatty acid metabolism is isocitrate lyase which participate in fatty acid catabolism to gain energy. Another special protein, worthing discussing, are aluminum resistance protein, which can let organisms tolerate high levels of aluminum in the environment, and carbonic anhydrase which can concentrate more CO2 in algae. There are nemerous ESTs with no similarity that we suppose the novel genes or genes not been sequenced yet. We also blasted the sequences with EST database in NCBI and found out 36 ESTs having high similarity to algae, in which 35 of them belong to the same order (Isochrysidales) algae, Emiliania Huxleyi, and only one ESTs belongs to another alga. It indicates that the classification of Isochrysis gabana is very special and phylogenesis of Isochrysis gabana is far away from the algae in the database. According the phylogenic tree of Isochrysis gabana, that Isochrysis gabana has closer relationship to Emiliania Huxleyi other than another algae and Arabidopsis. So,we can infer that the functional genes of Isochrysis gabana are quiet different from other species, and it is a good organism for scientific research. This information established in this study provides us to understand basically the physiology and acclimation of Isochrysis gabana. Futhermore, we can use this information to speed up the study of the functional genes in Isochrysis gabana in the future.
| Identifer | oai:union.ndltd.org:TW/092FJU00105020 |
| Date | January 2005 |
| Creators | Yen Shih Chieh, 顏士傑 |
| Contributors | Lin Yann Rong, 林彥蓉 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 107 |
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