Hatena arenicola
| Hatena arenicola | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Hatena | ||||||||||||
| Okamoto & Inouye , 2006 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Hatena arenicola | ||||||||||||
| Okamoto & Inouye , 2006 | ||||||||||||
Hatena arenicola is a marine unicellular eukaryote that forms a community with a green alga of the genus Nephroselmis . The species has so far only been found on a Japanese sandy beach, which is also indicated by its name (Hatena, Japaneseは て な, German for the mysterious and arenicola, Latin for sand dwelling ).
description
Hatena arenicola is flattened along the dorsiventral axis, ovoid in an anterior view, 30–40 µm long and 15–20 µm wide. Subapical, that is, below the tip, there is a 3–4 µm long and approx. 2 µm wide furrow from which the long anterior and the shorter posterior flagella emerge. Two rows of ejectisomes , easily recognizable with a light microscope, lie in front of the posterior end of the furrow. The large nucleus is located in the middle in the rear area of the cell. Most of the remaining cytoplasm is occupied by the endosymbiont , which is predominantly filled with its plastid . Compared to free- living Nephroselmis cells, the symbionts are up to ten times larger and have a reduced cytoplasm and several pyrenoids . They also have a complex eye-spot . In cells caught in the wild, the symbiont is rarely missing, but some symbionts are not fully developed, which could be explained by the life cycle.
Life cycle
During division, the host cell nucleus first migrates to the tip between the point of insertion of the flagella and the symbiont's eye spot . The symbiote then withdraws into the left half of the cell. After the formation of a second pair of flagella, the cell nucleus and cell divide, so that a green daughter cell with a symbiont and a colorless daughter cell arise. The colorless cells form a complex cell mouth and probably live predatory until a new symbiont is absorbed by phagocytosis . Since the exact strain of the symbiont is not known, the complete cycle has not yet been observed in the laboratory.
This symbiosis is of interest from an evolutionary point of view, as there is a change from heterotrophy to autotrophy and the ingestion of the symbiont by Hatena arenicola as predator could correspond to the ingestion of organelles by other eukaryotes, as described in the endosymbiont theory.
literature
- Noriko Okamoto, Isao Inouye: Hatena arenicola gen. Et sp. nov., a Katablepharid Undergoing Probable Plastid Acquisition. In: Protist . Volume 157, number 4, 2006, pp. 401-419 ( DOI: 10.1016 / j.protis.2006.05.011 , PDF ).
Web links
- Merry Youle: Caught in the Act , Small Things Considered - The Microbiology Blog, American Society for Microbiology , May 2, 2007 (images by Hatena ). Retrieved February 7, 2012.