Phosphorus starvation induces membrane remodeling and recycling in Emiliania huxleyi.
Nutrient availability is an important factor controlling phytoplankton productivity. Phytoplankton contribute c. 50% of the global photosynthesis and possess efficient acclimation mechanisms to cope with nutrient stress. We investigate the cellular response of the bloom-forming coccolithophore Emiliania huxleyi to phosphorus (P) scarcity, which is often a limiting factor in marine ecosystems. We combined mass spectrometry, fluorescence microscopy, transmission electron microscopy (TEM) and gene expression analyses in order to assess diverse cellular features in cells exposed to P limitation and recovery. Early starvation-induced substitution of phospholipids in the cells' membranes with galacto- and betaine lipids. Lipid remodeling was rapid and reversible upon P resupply. The PI3K inhibitor wortmannin reduced phospholipid substitution, suggesting a possible involvement of PI3K- signaling in this process. In addition, P limitation enhanced the formation and acidification of membrane vesicles in the cytoplasm. Intracellular vesicles may facilitate the recycling of cytoplasmic content, which is engulfed in the vesicles and delivered to the main vacuole. Long-term starvation was characterized by a profound increase in cell size and morphological alterations in cellular ultrastructure. This study provides cellular and molecular basis for future ecophysiological assessment of natural E. huxleyi populations in oligotrophic regions.
Department of Plant and Environmental Sciences, The Weizmann Institute of Science, Rehovot, 7610001, Israel.
Adva
A
Shemi
Department of Plant and Environmental Sciences, The Weizmann Institute of Science, Rehovot, 7610001, Israel.
Daniella
D
Schatz
Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543, USA.
Helen F
HF
Fredricks
Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543, USA.
Benjamin A S
BA
Van Mooy
Biological Services Department, The Weizmann Institute of Science, Rehovot, 7610001, Israel.
Ziv
Z
Porat
Department of Plant and Environmental Sciences, The Weizmann Institute of Science, Rehovot, 7610001, Israel.
Assaf
A
Vardi
D000469:Alkaline Phosphatase / Q000378:metabolism; D000730:Androstadienes / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D022162:Cytoplasmic Vesicles / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D004705:Endocytosis / Q000187:drug effects; D058087:Haptophyta / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008055:Lipids / Q000737:chemistry; D008954:Models, Biological; D010758:Phosphorus / Q000172:deficiency*; D000077191:Wortmannin
D000730:Androstadienes; D008055:Lipids; D010758:Phosphorus; D000469:Alkaline Phosphatase; D000077191:Wortmannin
alkaline phosphatase; autophagy; cell size; coccolithophores; lipid substitution; membrane vesicles; phosphate stress; phospholipids