SYNOPTIC DESCRIPTION OF THE PHYLUM JAKOBADA (CAVALIER-SMITH 1993)
| EUKARYA> EXCAVATA> EUEXCAVATA> JAKOBADA |
JAKOBADA LINKS
| The following descriptions come from Patterson (1999), Taylor (1999), Simpson and Patterson (2001), Cavalier-Smith (2003a and 2003b), and Simpson (2003). |
I. SYNONYMS: jakobids, core jakobids, Loukozoa
II. NUMBER: few taxa known in four genera.
III. PHYLUM CHARACTERISTICS:
- A. Structure and Physiology
- Cell Form: Unicellular.
- Flagella: Occur in pairs; usually 1 anteriorly (text with tooltip) An anteriorly-directed flagellum extends in the direction of the motion of the motile cell. The interpretation is that the flagellum functions by pulling the cell. and 1 posteriorly-directed (text with tooltip) Recurrent flagella bend to the posterior end of the cell. Typically, they are identified as recurrent when anteriorly-directed flagella are present. or recurrent. They may be isokont (text with tooltip) Isokont flagella are those flagella that are equal in length, form, and direction. or anisokont (text with tooltip) Anisokont flagella (n.) are those flagella that are unequal in length, form, or direction. . Posterior flagellum with a single vane (longitudinal flange).
- Basal Bodies: Basal bodies (text with tooltip) Basal bodies (also called kinetosomes) are organelles that are not membrane-bound. All eukaryotic flagella (also called undulipodia) are underlain or attached to the cell by the basal body. The basal body is a microtubular structure with the general formula 9(3)+0. They are indistinguishable from centrioles. orthogonal; microtubular rootlets from the basal bodies form bundles that support the edges of the feeding groove. Other roots connect the basal bodies to the nucleus thus forming a karyomastigont unit (text with tooltip) A karyomastigont is a 'unit' that includes basal bodies, flagellar roots, and a nucleus. .
- Cell Covering: Naked or loricate (text with tooltip) A lorica is a covering that occurs outside of the cell membrane. It is secreted by the cell and usually is organic. Loricas do not completely enclose the cell. Periplasts, structures similar to loricas do enclose the cell. Lorica stands for armour .
- Chloroplasts (text with tooltip) Chromoplast is the general term for a photosynthetic organelle. Technically, a chloroplast is a particular chromoplast in which the dominant chlorophylls are A and B. : Not present.
- Food Reserves: ?.
- Mitochondria: Present with tubular (text with tooltip) Mitochondrial cristae that form as extended saccate structures or tubes are called tubular cristae. , flat (text with tooltip) Flat cristae (crista, sing.) are wall-like cristae within certain mitochondria. , or discoid (text with tooltip) Discoid cristae (crista, sing.) are swollen tube-like cristae within certain mitochondria. cristae.
- Golgi: Present and associated with basal bodies.
- Nucleus: Connected to basal bodies via basal body roots to form a karyomastigont unit; two flagellar basal bodies associated with a nucleus.
- Centrioles: Not reported.
- Inclusions and Ejectile Organelles: Food vacuoles.
- B. Mitosis, Meiosis and Life History
- MITOSIS: Intranuclear spindle (text with tooltip) An intranuclear spindle elaborates within the nuclear membrane of an organism with closed mitosis. ?
- MEIOSIS: ?
- SEXUAL REPRODUCTION AND LIFE HISTORY: ?
- C. Ecology: Mostly free-living heterotrophs; attached or free-swimming.
| LITERATURE CITED Cavalier-Smith, T. 2003a. Protist phylogeny and the high-level classification of Protozoa. European Journal of Protistology. 39:338-348. Cavalier-Smith, T. 2003b. The excavate protozoan phyla Metamonada Grasse emend. (Anaeromonadea, Parabasalia, Carpediemonas, Eopharyngia) and Loukozoa emend. (Jakobea, Malawimonas): their evolutionary affinities and new higher taxa. International Journal of Systematic and Evolutionary Microbiology. 53:1741-1758. [ Edgcomb, V. P., A. J. Roger, A. G. B. Simpson, D. T. Kysela, and M. L. Sogin. 2001. Evolutionary relationships among “jakobid” flagellates as indicated by alpha- and beta-tubulin phylogenies. Molecular Biology and Evolution. 18(4):514-522. O’Kelly, C. J. 1993a. The Jakobid flagellates: structural features of Jakoba, Reclinomonas and Histonia and implications for the early diversification of eukaryotes. J. Euk. Microbiol. 40(5):627-636. Patterson, D. J. 1999. The diversity of eukaryotes. American Naturalist. 154 (Suppl.): S96–S124. Simpson, A. G. B. 2003. Cytoskeletal organization, phylogenetic affinities and systematics in the contentious taxon Excavata (Eukaryota). International Journal of Systematic and Evolutionary Microbiology. 53: 1759-1777. Simpson A. G. B. and D. J. Patterson. 1999. The ultrastructure of Carpediemonas membranifera: (Eukaryota), with reference to the ‘excavate hypothesis’. European Journal of Protistology. 35: 353-370. Simpson, A.G. B., and D. J. Patterson. 2001. On core jakobids and excavate taxa: the ultrastructure of: Jakoba incarcerata. Journal of Eukaryotic Microbiology. 48: 480–492. & 2001. Taylor, F. J. R. 1999. Ultrastructure as a control for protistan molecular phylogeny. The American Naturalist. 154(supplement): S125-S136. |
| By Jack R. Holt. Last revised: 02/12/2012 |
