Aplanochytrium
| Aplanochytrium | |
|---|---|
| Scientific classification | |
| Domain: | Eukaryota |
| (unranked): | SAR |
| Superphylum: | Heterokonta |
| Class: | Labyrinthulomycetes |
| Order: | Labyrinthulida |
| Family: | Aplanochytriidae |
| Genus: | Aplanochytrium |
The genera Aplanochytrium is part of the group Labyrinthulomycetes. It is a sister genera of Labyrinthula and thraustochytrids. The major characteristic of all three genera is the production of an extension of the plasma membrane and the ectoplasm called the ectoplasmic net, but its use is different in each genera. Aplanochytrium cells are not embedded in the ectoplasmic net but can move by gliding on the ectoplasmic threads.
Cells of the Aplanochytrium genus multiply by forming aplanospores in a spherical sporangium. The spores are then released and they move away by crawling along their own ectoplasmic thread. The aplanospores are non-flagellated asexual spores.
Aplanochytrium are found exclusively in a marine environment and live often with diverse host organisms. The symbiosis between aplanochytrium cells and the host organism can be of various origins, like commensal or parasite just to cite some examples.
The genera Aplanochytrium was identified as another member of the labyrinthulomycetes, because of the formation of non-flagellated and thus non-motile spores, that Bahnweg & Sparrow named "aplanospores". These specific spores formed the base of the name of the genus.
The genera Aplanochytrium was first described in 1972 by Bahnweg. First included in the order thraustochytrids, Aplanochytrium is now considered a sister group of the traustochytrids and Labyrinthula. The previous name of Aplanochytrium was Labyrinthuloides. Some species now considered part of the Aplanochytrium genera were first classified in other groups, typically Labyrinthula and thraustochytrids and only reassigned later on into the genera Aplanochytrium. An example is Aplanochytrium yorkensis, which was first considered as Labyrinthula and one year later reclassified into the genera Aplanochytrium.
Aplanochytrium are exclusively marine and their isolates have been found in water samples, sediments, detritus, oyster mantle, gastropods and seagrasses. They can either be free-living in water or as symbiont in host organisms, where some species act as parasitic symbiont.
The general shape of Aplanochytrium cells can be spherical to ovoid and their morphology is characterized by a single nucleus with a prominent nucleolus, numerous tubular mitochondria, a Golgi body and the presence of electron-dense regions at the periphery of the cell known as bothrosomes.
Cells belonging to the genera Aplanochytrium have an average length of 2.4-5 γm. The cell wall surrounding each cell is c formed by multiple layers of circular scales mostly composed of fructose, similar to the Labyrinthula. They do use photosynthesis as energy source and thus they often have a white or cream colour.
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Wikipedia