Myxozoa
| Myxozoa | ||||||||
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Myxobolus cerebralis in the triactinomyxon stage |
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| Systematics | ||||||||
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| Scientific name | ||||||||
| Myxozoa | ||||||||
| Grassé , 1970 | ||||||||
The Myxozoa are a taxon of parasitic organisms that, according to genome analyzes, belong to the cnidarians (Cnidaria). There are around 1200 species, which are assigned to around 50 genera.
features
The Myxozoa form different morphological stages, ranging from amoeboid single cells to complex cellular spores . The nettle capsules are transformed into polar capsules , which are used to penetrate the host .
Way of life
Myxozoa are parasitic cnidarians that use various animals of fresh and marine water as hosts. Fish parasites such as Myxobolus cerebralis , Ceratomyxa shasta , Kudoa thyrsites and Tetracapsuloides bryosalmonae are particularly well known . The wormlike Buddenbrockia plumatellae against it lives as a parasite in bryozoans (Bryozoa) of the class Phylactolaemata , more species are found in amphibians and reptiles . Parasites of the former genus Triactinomyxon , which attack annelids (Annelida) of the genus Tubifex , are known today that they are life stages of species of the fish parasite genus Myxobolus mentioned above .
Most species need two hosts for their development, and infection always occurs via spore capsules. In Tetracapsuloides bryosalmonae , as the specific epithet bryosalmone suggests, it is freshwater moss animals (Bryozoa) and trout fish (Salmonidae). Depending on the type, muscles, connective tissue or internal organs of the host are attacked; Tetracapsuloides bryosalmonae , for example, attacks the kidneys of the fish.
Within the target organism, the animals live as single cells (amoebula) or as syncytium , which physiologically represents a large cell with numerous cell nuclei. Special cell nuclei in the syncytium eventually divide through the formation of cell membranes and form infectious spores, which can then be ingested by the next host, usually with food. These spores typically consist of two or four capsule cells, which today are mostly interpreted as nettle cells , one or two cells from which a new syncytium forms after infection, and two other cells that form the spore wall.
Tribal history
The position of the Myxozoa in the system of living things was long considered unknown; often the group was as protists - Taxon viewed and the Apicomplexa asked. The existence of cell-cell connections and the structural protein collagen in the interstices between cells is, however, in addition to molecular genetic results, a clear sign of belonging to the multicellular animals (Metazoa).
The pile threads with which the animals attach themselves to their host are now mostly regarded as nettle tubes, the Myxozoa are then interpreted as cnidarians (Cnidaria).
They have four strands of muscles, but no basic mirror symmetry , which is the main characteristic of bilateria .
literature
- Kent, ML, Margolis, L. & Corliss, JO (1994): The demise of a class of protists: taxonomic and nomenclatural revisions proposed for the protist phylum Myxozoa Grasse, 1970 , Canadian Journal of Zoology 72 (5); 932-937 .
- Monteiro, AS, Okamura, B., and PWH Holland (2002): Orphan Worm Finds a Home: Buddenbrockia is a Myxozoan , Molecular Biology and Evolution 19; 968-971 (2002)
Individual evidence
- ^ E. Sally Changa, Moran Neuhof, Nimrod D. Rubinsteind, Arik Diamante, Hervé Philippef, Dorothée Huchonb, Paulyn Cartwright: Genomic insights into the evolutionary origin of Myxozoa within Cnidaria. PNAS, June 12, 2015, accessed July 30, 2016 .
- ↑ Enrico de Lazaro: Myxozoans: Widespread Parasites Are Actually 'Micro Jellyfish'. Sci-News, November 17, 2015, accessed July 30, 2016 .
- ^ Eva Jiménez-Guri, Hervé Philippe, Beth Okamura, and Peter WH Holland: Buddenbrockia Is a Cnidarian Worm , in: Science 317 (5834), 116, 2007, PDF Online
Web links
- Fiala, Ivan. 2008. Myxozoa . Version 10 July 2008 (under construction). in The Tree of Life Web Project