Coupling of silicon, carbon and nitrogen metabolisms in marine diatoms
Martin-Jézéquel, V.; Daoud, N.; Quéguiner, B. (1998). Coupling of silicon, carbon and nitrogen metabolisms in marine diatoms, in: Dehairs, F.A. et al. (Ed.) Integrated Marine System Analysis. European Network for Integrated Marine System Analysis FWO Vlaanderen: Proceedings of the second network meeting (Brussels, May 29-31, 1997). pp. 65-83 In: Dehairs, F.A.; Elskens, M.; Goeyens, L. (Ed.) (1998). Integrated Marine System Analysis - European Network for Integrated Marine System Analysis FWO Vlaanderen: Proceedings of the second network meeting (Brussels, May 29-31, 1997). VUB. Laboratorium voor Analytische Chemie: Brussel. 376 pp., more |
| Keywords | Algae > Diatoms
Cycles > Chemical cycles > Geochemical cycle > Biogeochemical cycle > Nutrient cycles > Carbon cycle
Cycles > Chemical cycles > Geochemical cycle > Biogeochemical cycle > Nutrient cycles > Nitrogen cycle
Cycles > Chemical cycles > Geochemical cycle > Biogeochemical cycle > Nutrient cycles > Silicon cycle
Marine/Coastal |
| Authors | | Top | - Martin-Jézéquel, V.
- Daoud, N.
- Quéguiner, B.
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| Abstract | The siliceous structures of diatom walls have been studied both as models of biomineralization and for the purpose of taxonomic identification. The frustule is composed of hydrated silica and organic constituents, and the knowledge of the chemical composition of this coating may allow insight in the mechanisms of silicification. Silicon is taken up asorthosilicic acid (Si(OH)4) which then polymerizes inside the cell within a silicon-deposition vesicle (SDV). Heterogeneous nucleation and growth via autopolymerization may be subsequently induced by the surface of the SDV to form amorphous biogenic silica (opal). Orthosilicic acid uptake as well as silica deposition are mainly confined to one part of the cell cycle and the new valves are made up during cell division. Silicon incorporation is thenclosely related to the cell growth. The metabolic and physicochemical dependencies of the polymerization process have not yet been elucidated. The energy required for silicon metabolism is mainly originating from respiration processes (oxidative phosphorylation). Silicification is controlled at the cellular level by an organic template which is mainly composed by proteins enriched in serine and glycine. These amino acids are obligatorymetabolites from photorespiration The glycolate pathway via serine and glycine appears to be rudimentary in diatoms when compared to the green algae, and the activation of the serine/glycine pathways must be original in diatoms. Preliminary experiments have revealed close relationships between the serine and glycine synthesis, and the cell division. Thus, we can postulate a true and obligate relationship between photorespiration, and silification process in diatoms. |
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