“Pomacytosis”—Semi-extracellular phagocytosis of cyanobacteria by the smallest marine algae

The smallest algae, less than 3 μm in diameter, are the most abundant eukaryotes of the World Ocean. Their feeding on planktonic bacteria of similar size is globally important but physically enigmatic. Tiny algal cells tightly packed with the voluminous chloroplasts, nucleus, and mitochondria appear...

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Bibliographic Details
Published in:	PLoS biology Vol. 16; no. 1; p. e2003502
Main Authors:	Kamennaya, Nina A., Kennaway, Gabrielle, Fuchs, Bernhard M., Zubkov, Mikhail V.
Format:	Journal Article
Language:	English
Published:	United States Public Library of Science 05.01.2018 Public Library of Science (PLoS)
Subjects:	Algae Aquatic Organisms - physiology Bacteria Biogeochemistry Biology and Life Sciences Braarudosphaera Cell cycle Cell Membrane Cell Nucleus Cell size Chloroplasts Councils Cyanobacteria Cyanobacteria - metabolism Cyanobacteria - physiology Data collection Earth Sciences Ecology and Environmental Sciences Ecosystems Enzymes Eukaryotes Flow cytometry Funding Internalization Library collections Marine algae Microbiological research Mitochondria Nitrogen Nuclei Nuclei (cytology) Oceanography Phagocytosis Phagocytosis - physiology Physiological aspects Prey Prochlorococcus Prochlorococcus - physiology Research and Analysis Methods Short Reports United Kingdom > UK
ISSN:	1545-7885, 1544-9173, 1545-7885
Online Access:	Get full text
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Summary:	The smallest algae, less than 3 μm in diameter, are the most abundant eukaryotes of the World Ocean. Their feeding on planktonic bacteria of similar size is globally important but physically enigmatic. Tiny algal cells tightly packed with the voluminous chloroplasts, nucleus, and mitochondria appear to have insufficient organelle-free space for prey internalization. Here, we present the first direct observations of how the 1.3-μm algae, which are only 1.6 times bigger in diameter than their prey, hold individual Prochlorococcus cells in their open hemispheric cytostomes. We explain this semi-extracellular phagocytosis by the cell size limitation of the predatory alga, identified as the Braarudosphaera haptophyte with a nitrogen (N2)-fixing endosymbiont. Because the observed semi-extracellular phagocytosis differs from all other types of protistan phagocytosis, we propose to name it "pomacytosis" (from the Greek πώμα for "plug").
Bibliography:	new_version ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 content type line 23 The authors have declared that no competing interests exist.
ISSN:	1545-7885 1544-9173 1545-7885
DOI:	10.1371/journal.pbio.2003502