Bikont

From Wikipedia, the free encyclopedia

Bikonts
Ceratium hirundinella
Scientific classification
Domain: Eukaryota (unranked) Bikonta
Supergroups
Apusozoa Rhizaria Excavata Archaeplastida Chromalveolata

A Bikont ("two flagella") is a eukaryotic cell with two flagella, as its name suggests. 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 (Cavalier-Smith, 2006). The genes are separately translated in unikonts.

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.^[1]

[edit] References

1. ^ Burki F, Shalchian-Tabrizi K, Minge M, Skjæveland Å, Nikolaev SI, et al. (2007). "Phylogenomics Reshuffles the Eukaryotic Supergroups". PLoS ONE 2 (8: e790): e790. doi:10.1371/journal.pone.0000790. 

• Thomas Cavalier-Smith (2006). "Protist phylogeny and the high-level classification of Protozoa". European Journal of Protistology 39 (4): 338-348. 

• Alexandra Stechmann and Thomas Cavalier-Smith (2003). "The root of the eukaryote tree pinpointed". Current Biology 13 (17).