Trypanosomatida

Source: Wikipedia, the free encyclopedia.

Trypanosomes
Temporal range:
Ma
Trypanosoma cruzi
Scientific classification Edit this classification
Domain: Eukaryota
Phylum: Euglenozoa
Class: Kinetoplastea
Subclass: Metakinetoplastina
Order: Trypanosomatida
Kent 1880
Family: Trypanosomatidae
Doflein 1901
Subfamily

Trypanosomatida is a group of

parasitic, found primarily in insects.[1] A few genera have life-cycles involving a secondary host, which may be a vertebrate, invertebrate or plant. These include several species that cause major diseases in humans.[2] Some trypanosomatida are intracellular parasites, with the important exception of Trypanosoma brucei
.

Medical importance

The three major human diseases caused by trypanosomatids are; African trypanosomiasis (sleeping sickness, caused by Trypanosoma brucei and transmitted by tsetse flies[3]), South American trypanosomiasis (Chagas disease, caused by T. cruzi and transmitted by triatomine bugs), and leishmaniasis (a set of trypanosomal diseases caused by various species of Leishmania transmitted by sandflies[4]).

Evolution

The family is known from fossils of the extinct genus

mya) and Dominican amber from the Burdigalian (20–15 mya) of Hispaniola.[5] The genus Trypanosoma is also represented in Dominican amber in the extinct species T. antiquus.[6]

Taxonomy

Three genera are

Kinetoplastibacterium genus. [citation needed
]

T. equiperdum
L. donovani
C. luciliae
P. serpens
A. deanei

Life cycle

Some trypanosomatids only occupy a single

intracellular environments. [citation needed
]

Among commonly studied examples, T. brucei, T. congolense, and T. vivax are extracellular, while T. cruzi and Leishmania spp. are intracellular.[8] Trypanosomatids with intracellular stages express δ-amastin proteins on their surfaces.[8] de Paiva et al., 2015 illuminates δ-amastins' roles in intracellular success.[8]

Sexual reproduction

Trypanosomatids that cause globally known diseases such leishmaniasis (Leishmania species), African trypanosomiasis referred to as sleeping sickness (Trypanosoma brucei), and Chagas disease (Trypanosoma cruzi) were found to be capable of meiosis and genetic exchange.[9] These findings indicate the capability for sexual reproduction in the Trypanosomatida.[9]

Morphologies

Six main morphologies

A variety of different morphological forms appear in the life cycles of trypanosomatids, distinguished mainly by the position, length and the cell body attachment of the flagellum. The kinetoplast is found closely associated with the basal body at the base of the flagellum and all species of trypanosomatid have a single nucleus. Most of these morphologies can be found as a life cycle stage in all trypanosomatid genera however certain morphologies are particularly common in a particular genus. The various morphologies were originally named from the genus where the morphology was commonly found, although this terminology is now rarely used because of potential confusion between morphologies and genus. Modern terminology is derived from the Greek; "mastig", meaning whip (referring to the flagellum), and a prefix which indicates the location of the flagellum on the cell. For example, the amastigote (prefix "a-", meaning no flagellum) form is also known as the leishmanial form as all Leishmania have an amastigote life cycle stage.[citation needed]

  • Amastigote (leishmanial).[10] Amastigotes are a common morphology during an intracellular lifecycle stage in a mammalian host. All Leishmania have an amastigote stage of the lifecycle. Leishmania amastigotes are particularly small and are among the smallest eukaryotic cells. The flagellum is very short, projecting only slightly beyond the flagellar pocket.
  • Promastigote (leptomonad).[10] The promastigote form is a common morphology in the insect host. The flagellum is found anterior of nucleus and flagellum not attached to the cell body. The kinetoplast is located in front of the nucleus, near the anterior end of the body.
  • Epimastigote (crithidial).[10] Epimastigotes are a common form in the insect host and Crithidia and Blastocrithidia, both parasites of insects, exhibit this form during their life cycles. The flagellum exits the cell anterior of nucleus and is connected to the cell body for part of its length by an undulating membrane. The kinetoplast is located between the nucleus and the anterior end.
  • Trypomastigote (trypanosomal).[10] This stage is characteristic of the genus Trypanosoma in the mammalian host bloodstream as well as infective metacyclic stages in the fly vector. In trypomastigotes the kinetoplast is near the posterior end of the body, and the flagellum lies attached to the cell body for most of its length by an undulating membrane.
  • Opisthomastigote (herpetomonad).[10] A rarer morphology where the flagellum posterior of nucleus, passing through a long groove in the cell.
  • Endomastigote.[11] A morphotype where the flagellum does not extend beyond the deep flagellar pocket.

Other features

Notable characteristics of trypanosomatids are the ability to perform trans-splicing of RNA and possession of glycosomes, where much of their glycolysis is confined to. The acidocalcisome, another organelle, was first identified in trypanosomes.[12]

Bacterial endosymbiont

Kinetoplastibacterium
Scientific classification Edit this classification
Domain: Bacteria
Phylum: Pseudomonadota
Class: Betaproteobacteria
Order: Burkholderiales
Family: Alcaligenaceae
Genus:
Ca. "Kinetoplastibacterium"

Du et al., 1994

Six species of trypanosomatids are known to carry an additional proteobacterial endosymbiont, termed TPE (trypanosomatid proteobacterial endosymbionts). These trypansomatids (Strigomonas oncopelti, S. culicis, S. galati, Angomonas desouzai, and A. deanei) are in turn known as SHTs, for symbiont-harboring trypanosomatids. All such symbionts have a shared evolutionary origin and are classified in the Candidatus genus "Kinetoplastibacterium".[13]

As with many symbionts, the bacteria have a much reduced genome compared to their free-living relatives of genera

GTDB finds the genus sister to Proftella, a symbiont of Diaphorina citri.)[14] Reflecting their inability to live alone, they have lost genes dedicated to essential biological functions, relying on the host instead. They have modified their division to become synchronized with the host. In S. culicis at least, the TPE helps the host by synthesizing heme[13] and producing essential enzymes, staying tethered to the kinetoplast.[15]

References

  1. PMID 11334958
    .
  2. PMID 16504583.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  3. ^ "Trypanosomiasis, human African (sleeping sickness)". www.who.int. Archived from the original on 20 April 2018. Retrieved 14 May 2020.
  4. ^
    Rêgo, Felipe D.; Soares, Rodrigo Pedro (2021). "Lutzomyia longipalpis: an update on this sand fly vector". Anais da Academia Brasileira de Ciências. 93 (3).
    S2CID 233743387
    . e20200254.
    This review cites this research.
    Abbasi, Ibrahim; Trancoso Lopo de Queiroz, Artur; Kirstein, Oscar David; Nasereddin, Abdelmajeed; Horwitz, Ben Zion; Hailu, Asrat; Salah, Ikram; Mota, Tiago Feitosa; Fraga, Deborah Bittencourt Mothé (2018-11-13). "Plant-feeding phlebotomine sand flies, vectors of leishmaniasis, prefer Cannabis sativa". Proceedings of the National Academy of Sciences of the United States of America. 115 (46): 11790–11795.
    S2CID 53112660
    .
  5. PMID 18627624
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  6. PMID 15815152
    .
  7. ^ [1] Archived 2021-05-12 at the Wayback Machine "A new lineage of trypanosome from Australian vertebrates and terrestrial bloodsucking leeches (Haemadipsidae)"
  8. ^ a b c Silva Pereira, Sara; Trindade, Sandra; De Niz, Mariana; Figueiredo, Luisa M. (2019). "Tissue tropism in parasitic diseases". Open Biology. 9 (5): 190036.
    PMID 31088251
    .
  9. ^
    PMID 36218381
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  10. ^
    S2CID 4164112
    .
  11. S2CID 13880469
    .
  12. S2CID 31935658.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  13. ^
    PMID 23345457
    .
  14. ^ "GTDB - Tree at g__Kinetoplastibacterium". gtdb.ecogenomic.org. Archived from the original on 2022-12-20. Retrieved 2022-12-20.
  15. PMID 10220875
    .

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