| Project/Area Number |
17613010
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
極限環境生物学
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| Research Institution | Japan Agency for Marine-Earth Science and Technology |
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Principal Investigator |
FUJIWARA Yoshihiro Japan Agency for Marine-Earth Science and Technology, Japan Agency for Marine-Earth Science and Technology, Extremobiosphere Research Center, Sub Leader (20344294)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,610,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2005: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Maorithyas hadalis / Symbiosis / Chemosynthesis / Thioautotroph / Hadal zone / SoxB gene / Dual symbiosis / Fluorescence in situ hybridization / 化学合成生態系 / 機能遺伝子 / SoxB / 還元環境 / 海洋生態 / 共焦点顕微鏡 / 共生 / 遺伝子 / 細菌 |
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| Research Abstract |
The thyasrid clam Maorithyas hadalis is a conspicuous species in seep environments at depths of 7, 200-7,400 meters in the Japan Trench. Two distinct phylotypes of endosymbiotic bacteria were shown and spatial partitioning between the phylotypes was observed within the gill tissues.
The purpose of this study was to clarify the metabolic functions of the symbionts of M. hadalis and to understand the adaptation mechanism of the thyasirid clam to its hadal reducing environment. In 2005, detection of genes regarding sulfur oxidation was conducted from M. hadalis gills. The specific primers for PCR amplification of SoxB gene of symbionts from the vesicomyid clam Calyptogena okutanii were designed because of the similarity of 16S ribosomal RNA gene sequences of between the M. hadalis and C. okutanii symbionts. In 2007, SoxB gene was successfully amplified from the total extracted DNA of M. hadalis gills using the specific primers. Therefore, the sulfur oxidizing capability of one of the symbionts was supported by not only phylogeny but also metabolism.
For understanding the microdistribution of the SoxB gene in the host tissue, fluorescence in situ hybridization experiments were conducted in 2006. To determine the experimental conditions, the whale-fall mussel Adipicola pacifica was applied because flesh individuals of the mussel were easily available from our aquaria. The optimum conditions were set for fixation time and fixative. Flesh specimens were required for FISH experiments but there was no chance to collect new samples because the ROV Kaiko, which was the only ROV to reach the M. hadalis habitat, had been lost. Developments of new deep-diving ROV can be dissolve this problem.
This study showed the metabolic function regarding sulfur oxidation in the M. hadalis symbionts. It is important to recognize the wide distribution range of chemosynthetic symbioses between invertebrates and bacteria for understanding of their biogeography and evolution.
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