1996 Fiscal Year Final Research Report Summary
Physiological study on the mechanisms of calcium carbonate deposition of marine macro and microalgae
| Project/Area Number |
06839012
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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 | 時限 |
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| Research Field |
海洋生物学
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| Research Institution | Tokyo Gakugei University |
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Principal Investigator |
OKAZAKI Megumi Tokyo Gakugei University, Education, Professor, 教育学部, 教授 (40014732)
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| Project Period (FY) |
1994 – 1996
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| Keywords | Calcium carbonate / Calcite / Calcification / Biomineralization / ATPase / Calcareous algae / Coccolithophorid / Corallinaceae |
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| Research Abstract |
This study was made to elucidate the mechanisms of algal calcification (calcium carbonate deposition) using marine calcareous algae Corallinaceae (Rhodophyta) and coccolithophorids (Haptophyta). The following results were obtained.
1. Ratio of photosynthesis rate to calcification in a coccolithophorid alga Emiliania huxleyi was about 2.0 and it was shown that a reagent, hydroxyetyledine-1,1-diphosphonic acid (HEDP), was a specifc inhibitor of calcification. Using this reagent it was suggested that calcification and photosynthesis were coupled in inorganic carbon metabolism and that calcification was a strategy to photosynthesis to produce CO_2 for photosynthesis.
2. Coccoliths, calcified elaborate scales, of Pleurochrysis carterae consisted of two types of calcite elements and their arrangement in coccolith supported a V/R model proposed in E.huxleyi. This was the first demonstration of this model in coccolithophorids other than E.huxleyi.
3. Whole cells of P.carterae contained two Ca^2-binding acid polysaccharides (A,B) and B was also associated with coccoliths. Molecular weights of A and B were about 90 and 50kDa, respectively. The polysaccharide B inhibited strongly CaCO_3 deposition in vitro, but it induced calcite in metastable CaCO_3-saturated solution when it was immobilized on Sepharose beads.
4. Ca^<2.>-dependent ATP ase associated with plasma membrane of Serraticardia maxima (Corallinaceae) transported proton and it might play an important role in calcium carbonate deposition.
These results are very important not only to propose a model for biologically controled calcification including the formation of coral skeleton and molluscan shell, but also contribute to the fields of crystal engineering and of technology of biological CO_2 fixation into insoluble CaCO_3 as a countermeasure to the recent "CO_2 problem"
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Research Products
(12 results)
