Bikont


(Redirected from Bikonta)

Bikonts
Temporal range: Mesoproterozoic  – present
A radiolarian
Scientific classification
Domain: Eukaryota
(unranked): Bikonta
Cavalier-Smith, 1993
Subgroups

Corticata

Discoba

Synonyms
  • Biciliata Cavalier-Smith, 1993
  • Diaphoretickes Adl et al., 2012
  • Diphoda Derelle et al., 2015

A bikont ("two flagella") is any of the eukaryotic organisms classified in the group Bikonta. Many single-celled members of the group, and the presumed ancestor, have two flagella.[1]

The group includes all photosynthesizing eukaryotes.

Contents

Enzymes


Another shared trait of bikonts is the fusion of two genes into a single unit: the genes for thymidylate synthase (TS) and dihydrofolate reductase (DHFR) encode a single protein with two functions.[2]

The genes are separately translated in unikonts.

Relationships


Some research suggests that a unikont (a eukaryotic cell with a single flagellum) was the ancestor of opisthokonts (Animals, Fungi, and related forms) and Amoebozoa, and a bikont was the ancestor of Archaeplastida (Plants and relatives), Excavata, Rhizaria, and Chromalveolata. Cavalier-Smith has suggested that Apusozoa, which are typically considered incertae sedis, are in fact bikonts.

Relationships within the bikonts are not yet clear. Cavalier-Smith has grouped the Excavata and Rhizaria into the Cabozoa and the Archaeplastida and Chromalveolata into the Corticata, but at least one other study has suggested that the Rhizaria and Chromalveolata form a clade.[3]

An alternative to the Unikont–Bikont division was suggested by Derelle et al. in 2015,[4] where they proposed the acronyms OpimodaDiphoda respectively, as substitutes to the older terms. The name Diphoda is formed from the letters of DIscoba and diaPHOretickes (shown in capitals).

Cladogram


A "classical" cladogram (data from 2012, 2015) is:[5][6]

However, a cladogram (data from 2015, 2016) with the root in Excavata is[4][7][8]

The corticates correspond roughly to the bikonts. While Haptophyta, Cryptophyta, Glaucophyta, Rhodophyta, the SAR supergroup and viridiplantae are usually considered monophyletic, Archaeplastida may be paraphyletic, and the mutual relationships between these phyla are still to be fully resolved.

Recent reconstructions placed Archaeplastida and Hacrobia together in an "HA supergroup" or "AH supergroup", which was a sister clade to the SAR supergroup within the SAR/HA supergroup. However, this seems to have fallen out of favor as the monophyly of hacrobia has come under dispute.

See also


References


  1. ^ Burki F, Pawlowski J (October 2006). "Monophyly of Rhizaria and multigene phylogeny of unicellular bikonts" . Mol. Biol. Evol. 23 (10): 1922–30. doi:10.1093/molbev/msl055 . PMID 16829542 .
  2. ^ Thomas Cavalier-Smith (2003). "Protist phylogeny and the high-level classification of Protozoa". European Journal of Protistology. 39 (4): 338–348. doi:10.1078/0932-4739-00002 .
  3. ^ Burki F, Shalchian-Tabrizi K, Minge M, Skjæveland Å, Nikolaev SI, et al. (2007). Butler G (ed.). "Phylogenomics Reshuffles the Eukaryotic Supergroups" . PLoS ONE. 2 (8: e790): e790. doi:10.1371/journal.pone.0000790 . PMC 1949142 . PMID 17726520 .
  4. ^ a b Derelle, Romain; Torruella, Guifré; Klimeš, Vladimír; Brinkmann, Henner; Kim, Eunsoo; Vlček, Čestmír; Lang, B. Franz; Eliáš, Marek (17 February 2015). "Bacterial proteins pinpoint a single eukaryotic root" . Proceedings of the National Academy of Sciences. 112 (7): E693–E699. doi:10.1073/pnas.1420657112 . PMC 4343179 . PMID 25646484 .
  5. ^ Jackson, Christopher; Clayden, Susan; Reyes-Prieto, Adrian (2015). "The Glaucophyta: the blue-green plants in a nutshell" . Acta Societatis Botanicorum Poloniae. 84 (2): 149–165. doi:10.5586/asbp.2015.020 .
  6. ^ Burki, Fabien; Okamoto, Noriko; Pombert, Jean-François; Keeling, Patrick J. (7 June 2012). "The evolutionary history of haptophytes and cryptophytes: phylogenomic evidence for separate origins" . Proceedings of the Royal Society of London B: Biological Sciences. 279 (1736): 2246–2254. doi:10.1098/rspb.2011.2301 . PMC 3321700 . PMID 22298847 .
  7. ^ Cavalier-Smith, Thomas; Chao, Ema E.; Lewis, Rhodri (December 2015). "Multiple origins of Heliozoa from flagellate ancestors: New cryptist subphylum Corbihelia, superclass Corbistoma, and monophyly of Haptista, Cryptista, Hacrobia and Chromista" . Molecular Phylogenetics and Evolution. 93: 331–362. doi:10.1016/j.ympev.2015.07.004 . PMID 26234272 .
  8. ^ Eliáš, Marek; Klimeš, Vladimír; Derelle, Romain; Petrželková, Romana; Tachezy, Jan (2016). "A paneukaryotic genomic analysis of the small GTPase RABL2 underscores the significance of recurrent gene loss in eukaryote evolution" . Biology Direct. 11 (1): 5. doi:10.1186/s13062-016-0107-8 . PMC 4736243 . PMID 26832778 .

Further reading









Categories: Bikonts | Eukaryote unranked clades | Taxa named by Thomas Cavalier-Smith




Information as of: 06.07.2021 04:19:11 CEST

Source: Wikipedia (Authors [History])    License : CC-BY-SA-3.0

Changes: All pictures and most design elements which are related to those, were removed. Some Icons were replaced by FontAwesome-Icons. Some templates were removed (like “article needs expansion) or assigned (like “hatnotes”). CSS classes were either removed or harmonized.
Wikipedia specific links which do not lead to an article or category (like “Redlinks”, “links to the edit page”, “links to portals”) were removed. Every external link has an additional FontAwesome-Icon. Beside some small changes of design, media-container, maps, navigation-boxes, spoken versions and Geo-microformats were removed.

Please note: Because the given content is automatically taken from Wikipedia at the given point of time, a manual verification was and is not possible. Therefore LinkFang.org does not guarantee the accuracy and actuality of the acquired content. If there is an Information which is wrong at the moment or has an inaccurate display please feel free to contact us: email.
See also: Legal Notice & Privacy policy.