Unikont

Taxobox
color = #taxobox colour|incertae sedis
name = Unikonts
domain = Eukaryota
subdivision_ranks = Supergroups
subdivision =
Opisthokonta
Amoebozoa

Unikonts are members of the Unikonta, a taxonomic group proposed by Thomas Cavalier-Smith. The group includes eukaryotic cells with a single flagellum, at least ancestrally. Some research suggests that a unikont was the ancestor of opisthokonts (animals, fungi and related forms) and Amoebozoa, and a bikont (a eukaryotic cell with two flagella) was the ancestor of Archaeplastida (plants and relatives), Excavata, Rhizaria, and Chromalveolata.

The unikonts have a triple-gene fusion that is lacking in the bikonts. The three genes that are fused together in the unikonts but not bacteria or bikonts encode enzymes for synthesis of the pyrimidine nucleotides: carbamoyl phosphate synthase, dihydroorotase, aspartate carbamoyltransferase (Cavalier-Smith 2006). This must have involved a double fusion, a rare pair of events, supporting the shared ancestry of Opisthokonta and Amoebozoa.

The unikonts have a single centriole (Cavalier-Smith, 2002, 2006). Some unikonts have two centrioles but their origins are developmentally different than in the bikonts, indicating convergent evolution (Cavalier-Smith 2006).

References

* cite journal
authorlink = Thomas Cavalier-Smith
first = Thomas
last = Cavalier-Smith
title = The phagotrophic origin of eukaryotes and phylogenetic classification of Protozoa
journal = International Journal of Systematic and Evolutionary Microbiology
year = 2002 | volume = 52 | issue = 2 | pages = 297–354
issn = 1466-5026
url = http://ijs.sgmjournals.org/cgi/content/abstract/52/2/297
accessdate = 2007-06-08
format = abstract
pmid = 11931142

* cite journal
authorlink = Thomas Cavalier-Smith
first = Thomas
last = Cavalier-Smith
title = Protist phylogeny and the high-level classification of Protozoa
journal = European Journal of Protistology
year = 2003 | volume = 39 | issue = 4 | pages = 338–348
issn = 0932-4739
doi = 10.1078/0932-4739-00002

* cite journal
first = Alexandra
last = Stechmann
coauthors = Cavalier-Smith, Thomas
title = The root of the eukaryote tree pinpointed
journal = Current Biology
year = 2003 | volume = 13 | issue = 17 | pages = R665–R666
issn = 0960-9822
doi = 10.1016/S0960-9822(03)00602-X