Microsporidia

This article is about the parasitic fungi group. For the ascomycete fungi genus, see Microsporum. For the green algae genus, see Microspora. For the beetle family, see Microsporidae.

Microsporidia
Sporoblast of
Fibrillanosema crangonycis
Scientific classification Edit this classification
Domain: Eukaryota
Clade: Amorphea
Clade: Obazoa
(unranked): Opisthokonta
Clade: Holomycota
Kingdom: Fungi
Subkingdom: Rozellomyceta
Class: Microsporidiomycota
Benny 2007
Classes & orders[1]
Synonyms
  • Microsporidia Balbiani, 1882[2]
  • Microsporidiida Labbé, 1899
  • Cnidosporidia Doflein 190?
  • Microsporea Delphy, 1936 [1963], Levine et al., 1980[3][4]
  • Microsporidea Corliss & Levine 1963[5]
  • Microspora Sprague, 1969, 1977[6]
  • Microsporida Tuzet et al. 1971

Microsporidia are a group of spore-forming unicellular parasites. These spores contain an extrusion apparatus that has a coiled polar tube ending in an anchoring disc at the apical part of the spore.[7] They were once considered protozoans or protists, but are now known to be fungi,[8] or a sister group to true fungi.[9] These fungal microbes are obligate eukaryotic parasites that use a unique mechanism to infect host cells.[7] They have recently been discovered in a 2017 Cornell study to infect Coleoptera on a large scale. So far, about 1500 of the probably more than one million[10] species are named. Microsporidia are restricted to animal hosts, and all major groups of animals host microsporidia. Most infect insects, but they are also responsible for common diseases of crustaceans and fish. The named species of microsporidia usually infect one host species or a group of closely related taxa. Approximately 10 percent of the known species are parasites of vertebrates — several species, most of which are opportunistic, can infect humans, in whom they can cause microsporidiosis.

After infection they influence their hosts in various ways and all organs and tissues are invaded, though generally by different species of specialised microsporidia. Some species are lethal, and a few are used in biological control of insect pests. Parasitic castration, gigantism, or change of host sex are all potential effects of microsporidian parasitism (in insects). In the most advanced cases of parasitism the microsporidium rules the host cell completely and controls its metabolism and reproduction, forming a xenoma.[11]

Replication takes place within the host's cells, which are infected by means of unicellular spores. These vary from 1–40 μm, making them some of the smallest eukaryotes.[citation needed] Microsporidia that infect mammals are 1.0–4.0 μm.[12] They also have the smallest eukaryotic genomes.

The terms "microsporidium" (pl. "microsporidia") and "microsporidian" are used as vernacular names for members of the group. The name Microsporidium Balbiani, 1884[13] is also used as a catchall genus for incertae sedis members.[14]

Xenoma on flatfish caused by Glugea stephani
  1. ^ Cite error: The named reference OOF2022 was invoked but never defined (see the help page).
  2. ^ Balbiani, G (1882). "Sur les microsporidies ou psorospermies des Articulés". C. R. Acad. Sci. 95: 1168–71.
  3. ^ Delphy, J. 1936. Sous-règne des Protozoaires. In: Perrier, R. (ed.). La Faune de la France en tableaux synoptiques illustrés, vol 1A. Delagrave: Paris.
  4. ^ Levine, N. D.; et al. (1980). "A Newly Revised Classification of the Protozoa". The Journal of Protozoology. 27 (1): 37–58. doi:10.1111/j.1550-7408.1980.tb04228.x. PMID 6989987.
  5. ^ Corliss JO, Levine ND (1963). "Establishment of the Microsporidea as a new class in the protozoan subphylum Cnidospora". The Journal of Protozoology. 10 (Suppl): 26–27. doi:10.1111/jeu.1963.10.issue-s3.
  6. ^ Sprague, V. (1977). Classification and phylogeny of the Microsporidia. In: Comparative pathobiology. vol. 2, Systematics of the Microsporidia. Lee A. Bulla & Thomas C. Cheng (ed.). pp. 1–30. New York: Plenum Press, [1].
  7. ^ a b Franzen, C. (2005). How do Microsporidia invade cells?. Folia Parasitologica, 52(1–2), 36–40. doi.org/10.14411/fp.2005.005
  8. ^ Hibbett, D.S.; et al. (2007). "A higher level phylogenetic classification of the Fungi" (PDF). Mycological Research. 111 (5): 509–47. doi:10.1016/j.mycres.2007.03.004. PMID 17572334. S2CID 4686378.
  9. ^ Silar, Philippe (2016). Protistes Eucaryotes : Origine, Evolution et Biologie des Microbes Eucaryotes. HAL. p. 462. ISBN 978-2-9555841-0-1.
  10. ^ Hawksworth, David (2001). "The magnitude of fungal diversity: The 1.5 million spices estimate revisited". Mycological Research. 105 (12): 1422. doi:10.1017/S0953756201004725.
  11. ^ Ronny Larsson, Lund University (Department of Cell and Organism Biology) Cytology and taxonomy of the microsporidia Archived 2009-09-12 at the Wayback Machine 2004.
  12. ^ Didier, ES. (Apr 2005). "Microsporidiosis: an emerging and opportunistic infection in humans and animals". Acta Trop. 94 (1): 61–76. doi:10.1016/j.actatropica.2005.01.010. PMID 15777637.
  13. ^ Balbiani, G. 1884. Les Psorospermies des Articulés ou Microsporidies, pp. 150-168, 184. In: Leçons sur les sporozoaires. Paris: Doin, [2].
  14. ^ Hoffman, G. (1999). Parasites of North American Freshwater Fishes, 2nd edn, University of California Press, Berkeley, California, USA, p. 89, [3].