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Lipids of Ectocarpus fasciculatus (Phaeophyceae). Incorporation of [l-14C]Oleate and the Role of TAG and MGDG in Lipid Metabolism

Makewicz, Anja ; Gribi, Corinne ; Eichenberger, Waldemar

In: Plant and Cell Physiology, 1997, vol. 38, no. 8, p. 952-962

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    Titre
    • Lipids of Ectocarpus fasciculatus (Phaeophyceae). Incorporation of [l-14C]Oleate and the Role of TAG and MGDG in Lipid Metabolism
    Auteur
    • Makewicz, Anja. Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern/Switzerland
    • Gribi, Corinne. Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern/Switzerland
    • Eichenberger, Waldemar. Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern/Switzerland
    Type de document
    • Postprint
    Identifiant OAI-PMH
    • oai:doc.rero.ch:301322
    Summary
    Lipids and fatty acids of Ectocarpus fasciculatus (Ectocarpales, Phaeophyceae) were analyzed. Major polar lipids are monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfoquinovosyldiacylglycerol (SQDG), diacylglycerylhydroxymethyl-N,N,N-trimethyl-rβ-alanine (DGTA), phosphatidylcholine (PC), phospha-tidylethanolamine (PE), phosphatidylglycerol (PG) and phosphatidylinositol (PI). Diphosphatidylglycerol (DPG), phosphatidic acid (PA) and phosphatidyl-O-[N-(2-hydroxy-ethyl)glycine] (PHEG) were also present in small amounts. Nonpolar lipids mainly consist of triacylglycerol (TAG) and diacylglycerol (DAG). Major fatty acids are 16:0,18:1, α18:3, 18:4, 20:4 and 20:5. The positional distribution of fatty acids showed that molecular species of eukaryotic structure account for 99% in MGDG, 98% in DGDG, 62% in PG and 23% in SQDG. On incubation with [1-14C]18:1 for 30 min, 33% of the total label was detected in TAG, 16% in PG, 14% in PE, 10% in PC and 8% in MGDG. During 7 days of chase, the label in TAG, PG, PE and PC decreased and simultaneously increased in MGDG up to 41% of the total. In SQDG, labelled fatty acids were found in prokaryotic as well as in eukaryotic molecular species. During the experiment, the label shifted from 18:1 to 18:2, 18:3, 18:4 and, to a minor extent, to 20:4 and 20:5 acids indicating 18:1 to be processed by elongation and/or desaturation. These results suggest TAG to act as a major primary acceptor of exogenous oleate and to be involved in the transfer of fatty acids to MGDG and other polar lipids