name = Alveolata
image_caption = "
first = C.-W.
last = Li
coauthors = "et al"
title = Ciliated protozoans from the Precambrian Doushantuo Formation, Wengan, South China
journal = Geological Society, London, Special Publications
year=2007 | volume=286 | pages=151–156
doi = 10.1144/SP286.11 ] -
domain = Eukaryota
superphylum = Alveolata
subdivision_ranks = Phyla
DinoflagellataThe alveolates ("with cavities") are a major line of
protists. There are three phyla, which are very divergent in form, but are now known to be close relatives based on various ultrastructural and genetic similarities:
Ciliates, very common protozoa, with many short cilia arranged in rows
Apicomplexa, parasitic protozoa that lack locomotive structures except in gametes
Dinoflagellates, mostly marine flagellates, many of which have chloroplasts
The most notable shared characteristic is the presence of cortical alveoli, flattened vesicles packed into a continuous layer supporting the membrane, typically forming a flexible pellicle. In dinoflagellates they often form armor plates. Alveolates have mitochondria with tubular cristae, and their flagella or cilia have a distinct structure.
The Apicomplexa and dinoflagellates may be more closely related to each other than to the ciliates. Both have plastids, and most share a bundle or cone of
microtubules at the top of the cell. In apicomplexans this forms part of a complex used to enter host cells, while in some colorless dinoflagellates it forms a peduncle used to ingest prey. Various other genera are closely related to these two groups, mostly flagellates with a similar apical structure. These include free-living members in "Oxyrrhis" and "Colponema", and parasites in "Perkinsus", "Parvilucifera", "Rastrimonas", and the ellobiopsids. In 2001, direct amplification of the rRNAgene in marine picoplanktonsamples revealed the presence of two novel alveolate linages, called group I and II [López-García, P. "et al." (2001). Unexpected diversity of small eukaryotes in deep-sea Antarctic plankton. "Nature" 409: 603-7.] [Moon-van der Staay, S. Y. "et al." (2001). Oceanic 18S rDNA sequences from picoplankton reveal unsuspected eukaryotic diversity. "Nature" 409: 607-10.] . Group I has no cultivated relatives, while group II is related to the dinoflagellate parasite " Amoebophrya", which was classified until now in the Syndinialesdinoflagellate order.
Relationships between some of these the major groups were suggested during the 1980s, and between all three by Cavalier-Smith, who introduced the formal name Alveolata in 1991 [Cavalier-Smith, T. (1991). Cell diversification in heterotrophic flagellates. In The Biology of Free-living Heterotrophic Flagellates, ed. D.J. Patterson & J. Larsen. pp. 113-131. Oxford University Press.] . They were confirmed by a genetic study by Gajadhar "et al." [cite journal | author = Gajadhar, A. A. "et al."
title = Ribosomal RNA sequences of "Sarcocystis muris", "Theilera annulata", and "Crypthecodinium cohnii" reveal evolutionary relationships among apicomplexans, dinoflagellates, and ciliates
journal = Molecular and Biochemical Parasitology
year = 1991 | volume = 45 | pages = 147–153 | doi = 10.1016/0166-6851(91)90036-6] Some studies suggested the haplosporids, mostly parasites of marine invertebrates, might belong here but they lack alveoli and are now placed among the
The development of plastids among the alveolates is uncertain. Cavalier-Smith proposed the alveolates developed from a chloroplast-containing ancestor, which also gave rise to the
Chromista(the chromalveolatehypothesis). However, as plastids only appear in relatively advanced groups, others argue the alveolates originally lacked them and possibly the dinoflagellates and Apicomplexa acquired them separately.
* [http://tolweb.org/Alveolates/2379 Tree of Life: Alveolates]
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Look at other dictionaries:
Alveolate — Al ve*o*late, a. [L. alveolatus, fr. alveolus.] (Bot.) Deeply pitted, like a honeycomb. [1913 Webster] … The Collaborative International Dictionary of English
alveolate — [al vē′əlāt΄idal vē′ə lit] adj. [L alveolatus, hollowed out < alveolus, ALVEOLUS] honeycombed; full of small cavities: also alveolated [al vē′əlāt΄id] alveolation n … English World dictionary
alveolate — adjective Date: circa 1823 pitted like a honeycomb < alveolate pollen > … New Collegiate Dictionary
Alvéolate — Alveolata Alvéolobiontes … Wikipédia en Français
alveolate — adj. [L. alveolus, small cavity] Deeply pitted or having the appearance of a honeycomb … Dictionary of invertebrate zoology
alveolate — alveolation, n. /al vee euh lit, layt /, adj. having alveoli; deeply pitted, as a honeycomb. Also, alveolated. [1830 40; < L alveolatus. See ALVEOLUS, ATE1] * * * … Universalium
alveolate — 1. adjective Having a structure containing honeycomb like cavities 2. noun A grouping of protists comprising the ciliates, sporozoa and dinoflagellates … Wiktionary
alveolate — Pitted like a honeycomb. [L. alveolus, dim. of alveus, trough, hollow sac, cavity] * * * al·ve·o·late al vē ə lət adj pitted like a honeycomb al·ve·o·la·tion (.)al .vē ə lā shən n * * * al·ve·o·late (al veґə lāt) marked by honeycomb… … Medical dictionary
alveolate — adj. containing small hollows; made of many small cells (as in a honeycomb) … English contemporary dictionary
alveolate — a. Cellular, favose, honey combed … New dictionary of synonyms