title: Formation of lipid bodies and changes in fatty acid composition upon pre-akinete formation in Arctic and Antarctic Zygnema (Zygnematophyceae, Streptophyta) strains.
abstract: Filamentous green algae of the genus Zygnema (Zygnematophyceae, Streptophyta) are key components of polar hydro-terrestrial mats where they face various stressors including UV irradiation, freezing, desiccation and osmotic stress. Their vegetative cells can develop into pre-akinetes, i.e. reserve-rich, mature cells. We investigated lipid accumulation and fatty acid (FA) composition upon pre-akinete formation in an Arctic and an Antarctic Zygnema strain using transmission electron microscopy and gas chromatography coupled with mass spectrometry. Pre-akinetes formed after 9 weeks of cultivation in nitrogen-free medium, which was accompanied by massive accumulation of lipid bodies. The composition of FAs was similar in both strains, and α-linolenic acid (C18:3) dominated in young vegetative cells. Pre-akinete formation coincided with a significant change in FA composition. Oleic (C18:1) and linoleic (C18:2) acid increased the most (up to 17- and 8-fold, respectively). Small amounts of long-chain polyunsaturated FAs were also detected, e.g. arachidonic (C20:4) and eicosapentaenoic (C20:5) acid. Pre-akinetes exposed to desiccation at 86% relative humidity were able to recover maximum quantum yield of photosystem II, but desiccation had no major effect on FA composition. The results are discussed with regard to the capability of Zygnema spp. to thrive in extreme conditions.
authors.affiliation: Faculty of Science, Department of Botany, Charles University in Prague, Benátská 2, 128 01 Prague, Czech Republic martina.pichrtova@natur.cuni.cz.
authors.forename: Martina
authors.initials: M
authors.lastname: Pichrtová
authors.affiliation: Institute of Botany, Functional Plant Biology, University of Innsbruck, Sternwartestraße 15, 6020 Innsbruck, Austria.
authors.forename: Erwann
authors.initials: E
authors.lastname: Arc
authors.affiliation: Institute of Botany, Functional Plant Biology, University of Innsbruck, Sternwartestraße 15, 6020 Innsbruck, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Stöggl
authors.affiliation: Institute of Botany, Functional Plant Biology, University of Innsbruck, Sternwartestraße 15, 6020 Innsbruck, Austria.
authors.forename: Ilse
authors.initials: I
authors.lastname: Kranner
authors.affiliation: Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05 České Budějovice, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Hájek
authors.affiliation: Biocenter, Division of Bioinformatics, Medical University of Innsbruck, Innrain 80, 6020 Innsbruck, Austria.
authors.forename: Hubert
authors.initials: H
authors.lastname: Hackl
authors.affiliation: Institute of Botany, Functional Plant Biology, University of Innsbruck, Sternwartestraße 15, 6020 Innsbruck, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Holzinger
mesh_terms: D000864:Antarctic Regions; D001110:Arctic Regions; D003890:Desiccation; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D066292:Lipid Droplets / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D009997:Osmotic Pressure; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism; D057949:Streptophyta / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D005227:Fatty Acids; D045332:Photosystem II Protein Complex; D009584:Nitrogen
keywords: desiccation stress; fatty acid methyl ester; lipids; nitrogen starvation; polar green microalgae