User:Triscomn1/sandbox

Source: Wikipedia, the free encyclopedia.

A xenoma (also known as a ‘xenoparasitic complex’) is a growth caused by various

fungi, most notably microsporidia. It can occur on numerous organisms; however is predominantly found on fish.[1]

In most cases the

parasite and the host cell.[1] This forms the xenoparasitic complex. They tend to contain numerous cellular components as well as microsporidia at different developmental stages and spores. [2]

Not all microsporidia infections result in the formation of xenomas, it only occurs in the most extreme cases, and only a few microsporidia actually cause xenoma formation. [2]

History

Xenoparasitic complex was the term initially devised in the early

twentieth century to describe specific type ‘tumours’ found on various organisms, specific as the infections were caused by multiple subclasses of microsporidia. A paper published in 1922 by Weissenberg came up with the term ‘xenon’ for the xenoparasitic complexes he observed on sticklebacks caused by Glugea anomala, before eventually changing it to xenoma (xenon was already the name of a newly discovered chemical element). [1] [3]

testes of Taurulus bubalis where a dense microvillus layer is present for improved nutrient absorption. [1] [5]

Pathogenesis

Xenomas are provoked in various types of organisms, depending on the species of the

crustaceans and fish. [1] In addition to organism specificity, different species of parasite will have distinct host cell specificity, even if targeting the same organism. For example Microsporidium chaetogastris infects solely connective and muscle tissue cells of the annelid Chaetogaster diaphanus [6], whereas other species of microsporidia will target other tissue types. Another example is microsporidial gill disease in different species of fish caused by Loma salmonae. It was found that certain species had a higher prevalence of xenoma formation following infection with the same parasite i.e. xenomas per gill filament in chinook salmon was 8 to 33 times greater than in rainbow trout, showing differences in host cell susceptibility. [7]

Once a host cell is infected with the

fat globules and bundles of fibril. The nucleus may be in varying locations including the centre of the cell and may also vary in structure i.e. lobed, branched or divided into multiple fragments, but it will always be hypertrophic. [1] The host also commonly envelops the proliferating parasite and the host cell itself in layers of membranes and cells. [2]

In microsporidian xenomas the whole

parasite. The size of xenomas also varies with the type of parasite and host organism, and can range from a few micrometres to several millimetres.[1]

While it is generally accepted that the xenoma prevents spread of the

autoinfection. [1] Rupture of the xenoma may also result in dispersal of the infectious spores. [1] This can lead to the formation of other and more persistent forms of xenomas. [2]

Transmission of such

parasite in the lamina propria or by infiltration by sporoplasms using their polar tube. It is also very possible that these transport cells might themselves develop into a xenoma. [1]

Xenomas in Fish

Microsporidia is a common cause of disease in fish and so xenomas tend to be seen more frequent in fish than in other organisms. A paper published in 2002 listed 15 genera and 157 microsporidian species that cause disease in fish, [2] [12] however only ten of these genera induce xenoma formation. [8] Microsporidia genera that cause xenomas can therefore be quite diverse and so are characterised more comprehensively into several groups depending on their morphology [1]:

  • Xenomas without a thick wall and where the complete volume of the original cell is not converted into a xenoma [1]
  • Xenomas without a thick wall and where the complete volume of the original cell is converted into a xenoma [1]
  • Xenomas with a thick wall [1]

Recently fish-infecting microsporidia have been grouped into five classes depending on their molecular traits, a higher level of classification using SSU (small subunit) rDNA analysis. However molecular data is still lacking for several genera of microsporidia. [13]

Xenomas found in other organisms

Whilst xenomas are more highly characterised in

crustaceans, with at least 23 microsporidian species found in shrimp, most of them infecting muscular tissue. [14] Other species also infect the digestive tract, reproductive organs and their hepatopancreas. [14] Xenoma-like formations have also been found in species of shrew caused by Soricimyxum fegati, a type of myxosporea, showing they can also occur in mammals. [15]

Treatment

The host can eventually destroy the xenoma. Proliferative inflammation occurs in mature xenomas and transforms them into granulomas. Granuloma involution then ensues where phagocytosis kills the spores. [1]

Studies have shown it is possible to vaccinate against xenomas. One study showed that developing a vaccine using a 103 to 105 dose of killed spores from a low-virulence strain of Loma salmonae resulted in rainbow trout producing 85% less xenomas in their gills after experimental infection (compared to the control). This ultimately offers much improved protection to microsporidial gill disease which is common amongst rainbow trout. [16] Therapeutic drugs have proved ineffective at treating this disease and harvesting whole-spores is a relatively easy technique. [16]


See Also

Microsporidia

Glugea

Spore

References

  1. ^ a b c d e f g h i j k l m n o p q r s t u v Lom J, Dyková I. "Microsporidian xenomas in fish seen in wider perspective". Folia Parasitologica. 52: 69–81. Cite error: The named reference "Lom2005" was defined multiple times with different content (see the help page).
  2. ^ a b c d e Matos E, Corral L, Azevedo C. "Ultrastructural details of the xenoma of Loma myrophis (phylum Microsporidia) and extrusion of the polar tube during autoinfection". Diseases of Aquatic Organisms. 54: 203–207.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ^ Weissenberg R. "Mikrosporidien und Chlamydozoen als Zellparasiten von Fischen". Verh. Dtsch. Zool. Ges. 27: 41–43.
  4. ^ Chatton E. "Un complexe xéno-parasitaire morphologique et physiologique Neresheimeria paradoxa chez Fritillaria pellucida". C. R. Acad. Sci. Paris. 171: 55–57.
  5. ^ Chatton E, Courrier R. "Formation d'un complexe xénoparasitaire géant avec bordure en brosse, sous l'influence d'une Microsporidie, dans le testicule de Cottus bubalis". C. R. Soc. Biol. (Paris). 89: 579–583.
  6. ^ Schröder O. "Thelohania chaetogastris, eine neue in Chaetogaster diaphanus Gruith schmarotzende Microsporidienart". Arch. Protistenkd. 14: 119–133.
  7. ^ Ramsay JM, Speare DJ, Dawe SC, Kent ML. "Xenoma formation during microsporidial gill disease of salmonids caused by Loma salmonae is affected by host species (Oncorhynchus tshawytscha, O. kisutch, O. mykiss) but not by salinity". Diseases of Aquatic Organisms. 48: 125–131.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  8. ^ a b Mansour L, Prensier G, Jemaa SB, Hassine OKB, Méténier G, Vivarès CP, Cornillot E. "Description of a xenoma-inducing microsporidian, Microgemma tincae n. sp., parasite of the teleost fish Symphodus tinca from Tunisian coasts". Diseases of Aquatic Organisms. 65: 217–226.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. ^ Lee SJ, Yokoyama H, Ogawa K. "Modes of transmission of Glugea plecoglossi (Microspora) via the skin and digestive tract in an experimental infection model using rainbow trout, Oncorhyncus mykiss (Walbaum)". J. Fish Dis. 27: 435–444.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  10. ^ Lee SJ, Yokoyama H, Ogawa K. "Rapid in situ hybridisation technique for the detection of fish microsporidian parasites". Fish Pathol. 38: 117–119.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ^ Sánchez JG, Speare DJ, Markham RJF, Wright GM, Kibenge FSB. "Localization of the initial developmental stages of Loma salmonae in rainbow trout (Oncorhynchus mykiss)". Vet. Pathol. 38: 540–546.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  12. ^ Lom J. "A catalogue of described genera and species of microsporidians parasitic in fish". Syst Parasitol. 53: 81–99.
  13. ^ Lom J, Nilsen F. "Fish microsporidia: fine structural diversity and phylogeny". International Journal for Parasitology. 33: 107–127.
  14. ^ a b Wang TC, Nai YS, Wang CY, Solter LF, Hsu HC, Wang CH, Lo CF. "A new microsporidium, Triwangia caridinae gen. nov., sp. Nov. parasitizing fresh water shrimp, Caridina formosae (Decapoda: Atyidae) in Taiwan". Journal of Invertebrate Pathology. 112: 281–293.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  15. ^ Dyková I, Tyml T, Kostka M. "Xenoma-like formations induced by Soricimyxum fegati (Myxosporea) in three species of shrews (Soricomorpha: Soricidae), including records of new hosts". Folia Parasitologica. 58: 249–256.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  16. ^ a b Speare DJ, Markham RJF, Guselle NJ. "Development of an Effective Whole-Spore Vaccine To Protect against Microsporidial Gill Disease in Rainbow Trout (Oncorhyncus mykiss) by Using a Low-Virulence Strain of Loma salmonae". Clinical and Vaccine Immunology. 14: 1652–1654.
    doi:10.1128/CVI.00365-07.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
Retrieved from "https://en.wikipedia.org/w/index.php?title=User:Triscomn1/sandbox&oldid=546233166"