Kinetoplastida

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Kinetoplastida
Trypanosoma cruzi parasites
Scientific classification Edit this classification
Domain: Eukaryota
Phylum: Euglenozoa
Subphylum: Glycomonada
Class: Kinetoplastea
Honigberg, 1963 emend. Cavalier-Smith, 1981[1][2]
Subdivisions
Synonyms
  • Kinetoplastida Honigberg 1963 emend. Margulis 1974

Kinetoplastida (or Kinetoplastea, as a

parasites responsible for serious diseases in humans and other animals, as well as various forms found in soil and aquatic environments. The organisms are commonly referred to as "kinetoplastids" or "kinetoplasts".[5]

The kinetoplastids were first defined by

Bodo is a typical genus within kinetoplastida, which also includes various common free-living species which feed on bacteria. Others include Cryptobia and the parasitic Leishmania
.

Taxonomy

History

Honigberg created the taxonomic names Kinetoplastida and Kinetoplastea in 1963.[1] Since then there is no consensus on the use of either of the two as a definite taxon. Kinetoplastea is more widely used as the class,[6][7][8][9][10] while Kinetoplastida is mostly used to designate the order,[4][11][12][13] but is also used as a class.[3][14] Lynn Margulis, who initially accepted Kinetoplastida as an order in 1974, later placed it as a class.[15] Use of Kinetoplastida as an order also creates confusion as there is already an older name Trypanosomatida Kent, 1880, under which the kinetoplastids are most often placed.[16]

Classification

Kinetoplastida is divided into two subclasses - Metakinetoplastina and Prokinetoplastina.[17][18]

Morphology

Kinetoplastids are

eukaryotic and possess normal eukaryotic organelles, for example the nucleus, mitochondrion, golgi apparatus and flagellum. Along with these universal structures, kinetoplastids have several distinguishing morphological features such as the kinetoplast, sub-pellicular microtubule array and paraflagellar rod.[citation needed
]

Mitochondrion and kinetoplast DNA

Main article: Kinetoplast

The kinetoplast, after which the class is named, is a dense DNA-containing granule within the cell's single mitochondrion, containing many copies of the mitochondrial genome. The structure is made up of a network of concatenated circular DNA molecules and their related structural proteins along with DNA and RNA polymerases. The kinetoplast is found at the base of a cell's flagella and is associated to the flagellum basal body by a cytoskeletal structure.[citation needed]

Cytoskeleton

The cytoskeleton of kinetoplastids is primarily made up of

microfilaments but their role in the cytoskeleton is not clear. Other cytoskeletal structures include the specialised attachment between the flagellum and the kinetoplast.[citation needed
]

Flagella

All kinetoplastids possess at least one flagellum; species in the order trypanosomatida have one and bodonida have two. In kinetoplastids with two flagella most forms have a leading and trailing flagellum, the latter of which may be attached to the side of the cell. The flagella are used for locomotion and attachment to surfaces. The bases of the flagella are found in a specialised pocket structure which is also the location of the cytostome.[citation needed]

Life cycle

Kinetoplastids may be free-living or parasitic. The order trypanosomatida is notable as it includes many genera which are exclusively parasitic. Trypanosomatids may have simple life cycles in a single host or more complex ones which progress through multiple differentiation stages in two hosts. Dramatic morphological changes are possible between lifecycle stages. Diseases caused by members of the order trypanosomatida include sleeping sickness and Chagas disease, caused by species of Trypanosoma, and leishmaniasis, caused by species of Leishmania. Trypanosoma brucei can undergo meiosis as a likely part of a sexual cycle.[19][20] Leishmania major is also capable of a meiotic process that is likely part of a sexual cycle.[21]

Gallery

References

  1. ^ a b c Honigberg, B. M. (1963). "A contribution to systematics of the non-pigmented flagellates.". In Ludvík, J.; Lom, J.; Vávra J. (eds.). Progress in Protozoology: proceedings of the first International Congress on protozoology held at Prague. Academic Press.
  2. ^ Cavalier-Smith, T. (1981). Eukaryote kingdoms: seven or nine? Biosystems 14, 461–481.
  3. ^
    ISBN 978-0-12415-895-5
    .
  4. ^ a b "Kinetoplastida (kinetoplasts)". UniProt Consortium. Retrieved 22 January 2015.
  5. ^ Lukes, Julius (2009). "Kinetoplastida". The Tree of Life Web Project. Retrieved 10 September 2013.
  6. ^ "Kinetoplastea". EOL. Retrieved 22 January 2015.
  7. ^ "Kinetoplastea". World Register of Marine Species. Retrieved 22 January 2015.
  8. ^ "Kinetoplastea". ZipcodeZoo. Archived from the original on 22 January 2015. Retrieved 22 January 2015.
  9. ^ "Taxon: Class Kinetoplastea". The Taxonomicon. Archived from the original on 22 January 2015. Retrieved 22 January 2015.
  10. PMID 15388756
    .
  11. ^ "Kinetoplastida". EOL. Retrieved 22 January 2015.
  12. ^ "Kinetoplastida". Metalife. Archived from the original on 22 January 2015. Retrieved 22 January 2015.
  13. ^ "Kinetoplastida". NCBI Taxonomy. Retrieved 22 January 2015.
  14. ISBN 978-0-1951214-38
    .
  15. ISBN 978-0-12-373621-5.{{cite book}}: CS1 maint: multiple names: authors list (link
    )
  16. PMID 21030427
    .
  17. PMID 15388756
    .
  18. PMID 18814685
    .
  19. PMID 21321215
    .
  20. PMID 26027775
    .
  21. PMID 19359589
    .

Bibliography

  • Lumsden, W.H.R. & D.A. Evans (eds.). 1976-1979. Biology of the Kinetoplastida, 2 vols. London: Academic Press.

External links