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:''This article is about the genus Trypanosoma, for the specific human pathogens see Trypanosoma brucei and Trypanosoma cruzi.'' ''Trypanosoma'' is a genus of kinetoplastids (class Kinetoplastida), a monophyletic group of unicellular parasitic flagellate protozoa. The name is derived from the Greek ''trypano-'' (borer) and ''soma'' (body) because of their corkscrew-like motion. Most trypanosomes are heteroxenous (requiring more than one obligatory host to complete life cycle) and most are transmitted via a vector. Some, such as Trypanosoma equiperdum, are spread by direct contact. The majority of species are transmitted by blood-feeding invertebrates, but there are different mechanisms among the varying species. In an invertebrate host they are generally found in the intestine, but normally occupy the bloodstream or an intracellular environment in the mammalian host. Trypanosomes infect a variety of hosts and cause various diseases, including the fatal human diseases sleeping sickness, caused by ''Trypanosoma brucei'', and Chagas disease, caused by ''Trypanosoma cruzi''. The mitochondrial genome of the ''Trypanosoma'', as well as of other kinetoplastids, known as the kinetoplast, is made up of a highly complex series of catenated circles and minicircles and requires a cohort of proteins for organisation during cell division. ==History== The first species of ''Trypanosoma'' identified was in a trout by Valentin in 1841. They were identified in mammals 50–80 years later. == Taxonomy == The monophyly of the genus ''Trypanosoma'' is not supported by a number of different methods. Rather, the American and African trypanosomes constitute distinct clades, implying that the major human disease agents ''T. cruzi'' (cause of Chagas’ disease) and ''T. brucei'' (cause of African sleeping sickness) are not closely related to each other.〔Environmental kinetoplastid-like 18S rRNA sequences and phylogenetic relationships among Trypanosomatidae: Paraphyly of the genus Trypanosoma. Helen Piontkivska and Austin L. Hughes, Molecular and Biochemical Parasitology, November 2005, Volume 144, Issue 1, Pages 94–99, 〕 Phylogenetic analyses suggest an ancient split into a branch containing all Salivarian trypanosomes and a branch containing all non-Salivarian lineages. The latter branch splits into a clade containing bird, reptilian and Stercorarian trypanosomes infecting mammals and a clade with a branch of fish trypanosomes and a branch of reptilian or amphibian lineages.〔The molecular phylogeny of trypanosomes: evidence for an early divergence of the Salivaria. Jochen Haag, Colm O'hUigin and Peter Overath, Molecular and Biochemical Parasitology, 1 March 1998, Volume 91, Issue 1, Pages 37–49, 〕 Salivarians are trypanosomes of the subgenera of ''Duttonella'', ''Trypanozoon'', ''Pycnomonas'' and ''Nannomonas''. These trypanosomes are passed to the recipient in the saliva of the tsetse fly (''Glossina spp.'').〔(Definition of the word Salivarian at medical-dictionary.thefreedictionary.com )〕 Antigenic variation is a characteristic shared by the Salivaria, which has been particularly well-studied in ''T. brucei''.〔Sex and evolution in trypanosomes. Wendy Gibson, International Journal for Parasitology, 1 May 2001, Volume 31, Issues 5–6, Pages 643–647, 〕 The ''Trypanozoon'' subgenus contains the species ''Trypanosoma brucei'', ''T. rhodesiense'' and ''T. equiperdum''. The sub genus ''Duttonella'' contains the species ''T. vivax''. ''Nannomonas'' contains ''T. congolense''.〔Dihydrofolate reductases within the genus Trypanosoma. J.J. Jaffe, J.J. McCormack Jr and W.E. Gutteridge, Experimental Parasitology, 1969, Volume 25, Pages 311–318, 〕 Stercorians are trypanosomes passed to the recipient in the feces of insects from the subfamily ''Triatominae'' (most importantly ''Triatoma infestans'').〔()〕 This group includes ''Trypanosoma cruzi'', ''T. lewisi'', ''T. melophagium'', ''T. nabiasi'', ''T. rangeli'', ''T. theileri'', ''T. theodori''.〔(Stercoraria at medical-dictionary.thefreedictionary.com )〕 The sub genus ''Herpetosoma'' contains the species ''T. lewisi'' and the sub genus ''Schizotrypanum'' contains ''T. cruzi''.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Trypanosoma」の詳細全文を読む スポンサード リンク
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