Metabolic changes in Phaeocystis poucheti (Hariot) Lagerheim during the spring bloom in Belgian coastal waters |
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| Authors: | Christiane Lancelot |
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| Institution: | Laboratoire d''Océanographie, Université Libre de Bruxelles, Avenue F. D. Roosevelt, 50, B-1050 Bruxelles, Belgium |
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| Abstract: | Incorporation of 14C-bicarbonate into the major intracellular end-products of photosynthesis (protein, polysaccharide, lipid) and two classes of exoproducts (oligomers and polymers) was measured in Belgian coastal waters at different stages of the spring phytoplankton bloom, entirely dominated by the alga Phaeocystis poucheti. It was shown that intracellular protein synthesis contributed 20–42% of the total intracellular 14C fixed and was positively correlated with the inorganic nitrogen content of the surrounding medium. The decrease of protein synthesis following nitrogen depletion is balanced by an increase of intracellular polysaccharide synthesis, which varies from 22 to 42% of the intracellular 14C fixed, and by an increase in extracellular release of high molecular weight material (18–60% of total 14C fixed) which forms a mucous envelope where cells are embedded. Lipid synthesis is not correlated with the ambient inorganic nitrogen content and represents a rather constant proportion (about 20%) of the intracellular 14C fixed. |
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| Keywords: | Belgian coastal waters spring bloom Haptophyceae Proteins Polysaccharides Lipids excreted products Inorganic nitrogen |
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