Trypanosome Information & Trypanosome Links at HealthHaven.com

Trypanosomes
	Trypanosoma cruzi parasites
Scientific classification
Domain:	Eukaryota;
Kingdom:	Excavata;
Phylum:	Euglenozoa;
Subphylum:	Mastigophora;
Class:	Kinetoplastea;
Order:	Trypanosomatida;
Genera
	Blastocrithidia; Crithidia; Endotrypanum; Herpetomonas; Leishmania; Leptomonas; Phytomonas; Trypanosoma; Wallaceina

Trypanosomes are a group of kinetoplastid protozoa distinguished by having only a single flagellum. All members are exclusively parasitic, found primarily in insects.^[1] A few genera have life-cycles involving a secondary host, which may be a vertebrate or a plant. These include several species that cause major diseases in humans.^[2]

The most important trypanosomal diseases are trypanosomiasis (African Sleeping Sickness and South American Chagas Disease); these are caused by species of Trypanosoma. The Leishmaniases are a set of trypanosomal diseases caused by various species of Leishmania.

A variety of different forms appear in the life-cycles of trypanosomes, distinguished mainly by the position of the flagellum:

Amastigote (leishmanial)	- reduced or absent
Promastigote (leptomonad)	- anterior of nucleus, free from cell body
Epimastigote (crithidial)	- anterior of nucleus, connected by a short undulating membrane
Opisthomastigote (herpetomonad)	- posterior of nucleus, passing through a long groove in the cell
Trypomastigote (trypanosomal)	- posterior of nucleus, connected by a long undulating membrane

Most trypanosomes have at least amastigote and promastigote stages. Trypanosoma appears in all five forms, with the trypanosomal stage occurring in the vertebrate host. Trypanosoma brucei sub-species have two forms in the bloodstream of a vertebrate host, the rapidly dividing long-slender form and the non-dividing short stumpy form. The short stumpy parasites are adapted for uptake into the tsetse fly vector, and are non-proliferative in comparison with the slender forms.

Unique to the African trypanosome Trypansoma brucei is the expression of a variable surface glycoprotein (VSG) coat on the cell surface, which undergoes constant variation in order to evade the humoral immune system and host antibodies. It is thought that recombination via double-stranded DNA breaks from a repertoire of about 100 complete VSG genes, and a large number of VSG-related sequences, is responsible for the vast diversity of the parasite.^[3] This recombination would retain effectiveness in immune evasion by maintaining diversity.

The acidocalcisome organelle was first identified in trypanosomes. ^[4]

A notable characteristic of trypanosomes is that they are able to perform Trans-splicing.

[edit] References

^ Podlipaev S (May 2001). "The more insect trypanosomatids under study-the more diverse Trypanosomatidae appears". Int. J. Parasitol. 31 (5-6): 648–52. doi:10.1016/S0020-7519(01)00139-4. PMID 11334958.
^ Simpson AG, Stevens JR, Lukes J (April 2006). "The evolution and diversity of kinetoplastid flagellates". Trends Parasitol. 22 (4): 168–74. doi:10.1016/j.pt.2006.02.006. PMID 16504583.
^ Taylor JE, Rudenko G (November 2006). "Switching trypanosome coats: what's in the wardrobe?". Trends Genet. 22 (11): 614–20. doi:10.1016/j.tig.2006.08.003. PMID 16908087.
^ http://www.nature.com/nrmicro/journal/v3/n3/full/nrmicro1097.html Nature Reviews Microbiology 3, 251-261 (March 2005) | doi:10.1038/nrmicro1097 Acidocalcisomes? Conserved from bacteria to man? Roberto Docampo, Wanderley de Souza, Kildare Miranda, Peter Rohloff Silvia N. J. Moreno

[edit] External links

Trykipedia, Trypanosomatid specific ontologies

Tree of Life: Trypanosomatida

[0] Podlipaev S (May 2001). "The more insect trypanosomatids under study-the more diverse Trypanosomatidae appears". Int. J. Parasitol. 31 (5-6): 648–52. doi:10.1016/S0020-7519(01)00139-4. PMID 11334958.

[1] Simpson AG, Stevens JR, Lukes J (April 2006). "The evolution and diversity of kinetoplastid flagellates". Trends Parasitol. 22 (4): 168–74. doi:10.1016/j.pt.2006.02.006. PMID 16504583.

[2] Taylor JE, Rudenko G (November 2006). "Switching trypanosome coats: what's in the wardrobe?". Trends Genet. 22 (11): 614–20. doi:10.1016/j.tig.2006.08.003. PMID 16908087.

[3] ttp://www.nature.com/nrmicro/journal/v3/n3/full/nrmicro1097.html Nature Reviews Microbiology 3, 251-261 (March 2005) | doi:10.1038/nrmicro1097 Acidocalcisomes? Conserved from bacteria to man? Roberto Docampo, Wanderley de Souza, Kildare Miranda, Peter Rohloff Silvia N. J. Moreno

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