碩士 / 國立臺灣海洋大學 / 海洋生物研究所 / 94 / Trichodesmium spp. is a nitrogen-fixing filamentous cyanobacterium that contributes a major fraction of new nitrogen input to the open ocean. In this study, microscope observation and sequences analysis were used to determine the species composition and relative abundance of Trichodesmium spp. in the vicinity of Gueishan Island. The results indicated that Trichodesmium always existed in the upper water column with depths shallower than 50 m. In 2004 and 2005, high abundance (224.6 trichomes L-1 ) was observed in spring (April and May) and fall (September), while low abundance was observed in summer (June) and winter (December). The length of trichomes varied with the seasons. Trichomes became longer when the sea was calm (April, May, and September). Based on sequence analysis of het R, 16S rRNA, and nif H individual colonies of Trichodesmium spp. were grouped into 4 main clusters. The first group (Cluster I) included species related to T. thiebautii. The second group (Cluster IIa) included specimens closely related to B49 and B51-3, two specimen collected in Equatorial Pacific Ocean. The third group (Cluster IIb-IIc) is a novel Trichodesmium lineage. The fourth group(Cluster III) is T. erythraeum. Amino acid sequences suggested a similar trend. The sequences of mixed samples showed that T. erythraeum was the dominated species, contributing 33~80% to total Trichodesmium sequences. However, the microscope observation revealed that T. thiebautii and T. erythraeum contributed approximately equally. Because colony morphology is changeable and cell dimensions makes a varies greatly, identification of species is difficult using morphological characteristics alone. Sequence analysis of genes is a good supplementary method to describe the phylogenetic relationship in Trichodesmium genus.
| Identifer | oai:union.ndltd.org:TW/094NTOU5270011 |
| Date | January 2006 |
| Creators | Hsuan-Fan Wang, 王玄芳 |
| 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 | 68 |
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