Polychaos dubium

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Polychaos dubium
Scientific classification
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Species:
P. dubium
Binomial name
Polychaos dubium
(Schaeffer, 1916) Schaeffer, 1926 [1]
Synonyms
  • Amoeba dubiaSchaeffer, 1916 [2]
  • Polychaos dubiaSchaeffer, 1926

Polychaos dubium is a freshwater amoeboid and one of the larger species of single-celled eukaryote. Like other amoebozoans, P. dubium moves by means of temporary projections called pseudopods. P. dubium reportedly has one of the largest genome size of any organism known, [3] though the authors of a 2004 study suggest treating that measurement with caution. [4]

Contents

Polychaos dubium was previously known as Amoeba dubia. [2] The author who named the species later recognized it as different from species of Amoeba , and so designated it the type species of the genus Polychaos . [1] Unlike species of Amoeba, P. dubium lacks longitudinal ridges on its pseudopods. [5]

Physical characteristics

A few characteristics distinguish Polychaos dubium from other species of Polychaos. The crystals floating in its cytoplasm take the shape of flat bipyramids, flat plates, or clustered platelets. The nucleus is ellipsoid in shape, has granules next to the membrane, and lacks an endosome. The cell is usually polypodal (has many pseudopodia), and the endoplasm and ectoplasm of the cytoplasm are clear. [5] During rapid locomotion, P. dubium may become monopodial (present only one pseudopod), [6] but there are an average of 12 pseudopodia. [7]

Polychaos dubium has one of the largest genomes known for any organism, consisting of 670 billion base pairs or 670 Gbp, [4] which is over 200 times larger than the human genome (3.2 Gbp). The authors of one 2004 study, however, suggest treating that measurement with caution, because it was taken before the advent of modern genomic methods. [4]

Ecology and range

P. dubium inhabits freshwater and is herbivorous, [5] eating algae. [6] Specimens have been collected in North America, and northern Europe. [8]

Related Research Articles

<span class="mw-page-title-main">Pseudopodia</span> False leg found on slime molds, archaea, protozoans, leukocytes and certain bacteria

A pseudopod or pseudopodium is a temporary arm-like projection of a eukaryotic cell membrane that is emerged in the direction of movement. Filled with cytoplasm, pseudopodia primarily consist of actin filaments and may also contain microtubules and intermediate filaments. Pseudopods are used for motility and ingestion. They are often found in amoebas.

<span class="mw-page-title-main">Amoebozoa</span> Phylum of protozoans

Amoebozoa is a major taxonomic group containing about 2,400 described species of amoeboid protists, often possessing blunt, fingerlike, lobose pseudopods and tubular mitochondrial cristae. In traditional and currently no longer supported classification schemes, Amoebozoa is ranked as a phylum within either the kingdom Protista or the kingdom Protozoa. In the classification favored by the International Society of Protistologists, it is retained as an unranked "supergroup" within Eukaryota. Molecular genetic analysis supports Amoebozoa as a monophyletic clade. Modern studies of eukaryotic phylogenetic trees identify it as the sister group to Opisthokonta, another major clade which contains both fungi and animals as well as several other clades comprising some 300 species of unicellular eukaryotes. Amoebozoa and Opisthokonta are sometimes grouped together in a high-level taxon, variously named Unikonta, Amorphea or Opimoda.

<i>Naegleria</i> Genus of protists

Naegleria is a free living amoebae protist genus consisting of 47 described species often found in warm aquatic environments as well as soil habitats worldwide. It has three life cycle forms: the amoeboid stage, the cyst stage, and the flagellated stage, and has been routinely studied for its ease in change from amoeboid to flagellated stages. The Naegleria genera became famous when Naegleria fowleri, a human pathogenic strain and the causative agent of primary amoebic meningoencephalitis (PAM), was discovered in 1965. Most species in the genus, however, are non pathogenic.

<span class="mw-page-title-main">Lobosa</span> Phylum of protozoans

Lobosa is a taxonomic group of amoebae in the phylum Amoebozoa. Most lobosans possess broad, bluntly rounded pseudopods, although one genus in the group, the recently discovered Sapocribrum, has slender and threadlike (filose) pseudopodia. In current classification schemes, Lobosa is a subphylum, composed mainly of amoebae that have lobose pseudopods but lack cilia or flagella.

<span class="mw-page-title-main">Contractile vacuole</span> Organelle used in regulating osmosis

A contractile vacuole (CV) is a sub-cellular structure (organelle) involved in osmoregulation. It is found predominantly in protists and in unicellular algae. It was previously known as pulsatile or pulsating vacuole.

<i>Chaos</i> (genus) Genus of microscopic organisms

Chaos is a genus of single-celled amoeboid organisms in the family Amoebidae. The largest and best-known species, the so-called "giant amoeba" Chaos carolinensis, can reach lengths of 5 mm, although most specimens fall between 1 and 3 mm.

<span class="mw-page-title-main">Amoebidae</span>

The Amoebidae are a family of Amoebozoa, including naked amoebae that produce multiple pseudopodia of indeterminate length. These are roughly cylindrical with granular endoplasm and no subpseudopodia, as found in other members of the class Tubulinea. During locomotion one pseudopod typically becomes dominant and the others are retracted as the body flows into it. In some cases the cell moves by "walking", with relatively permanent pseudopodia serving as limbs.

<i>Amoeba proteus</i>

Amoeba proteus is a large species of amoeba closely related to another genus of giant amoebae, Chaos. As such, the species is sometimes given the alternative scientific name Chaos diffluens.

<span class="mw-page-title-main">Tubulinea</span> Class of protozoans

The Tubulinea are a major grouping of Amoebozoa, including most of the more familiar amoebae genera like Amoeba, Arcella, Difflugia and Hartmannella.

<i>Paulinella</i> Genus of single-celled organisms

Paulinella is a genus of at least eleven species including both freshwater and marine amoeboids.

<i>Amoeba</i> (genus) Genus of Protozoa

Amoeba is a genus of single-celled amoeboids in the family Amoebidae. The type species of the genus is Amoeba proteus, a common freshwater organism, widely studied in classrooms and laboratories.

<span class="mw-page-title-main">Amoeboid movement</span> Mode of locomotion in eukaryotic cells

Amoeboid movement is the most typical mode of locomotion in adherent eukaryotic cells. It is a crawling-like type of movement accomplished by protrusion of cytoplasm of the cell involving the formation of pseudopodia ("false-feet") and posterior uropods. One or more pseudopodia may be produced at a time depending on the organism, but all amoeboid movement is characterized by the movement of organisms with an amorphous form that possess no set motility structures.

<span class="mw-page-title-main">Testate amoebae</span>

Testate amoebae are a polyphyletic group of unicellular amoeboid protists, which differ from naked amoebae in the presence of a test that partially encloses the cell, with an aperture from which the pseudopodia emerge, that provides the amoeba with shelter from predators and environmental conditions.

Polychaos is an amoeboid genus in the Amoebozoa group. Several characters unite the species in this genus. The pseudopods meld at their bases when the organism is moving, and have dorsal, longitudinal ridges. The nucleus is oval or ellipsoid.

<i>Paris japonica</i> Species of flowering plant

Paris japonica is a Japanese species of plants in the genus Paris in the family Melanthiaceae.

<i>Collodictyon</i> Genus of algae

Collodictyon is a genus of single-celled, omnivorous eukaryotes belonging to the collodictyonids, also known as diphylleids. Due to their mix of cellular components, Collodictyonids do not belong to any well-known kingdom-level grouping of that domain and this makes them distinctive from other families. Recent research places them in a new 'supergroup' together with rigifilids and Mantamonas, with the so-far informal name 'CRuMs'.

<i>Reticulomyxa</i> Genus of single-celled organisms

Reticulomyxa is a monospecific genus of freshwater foraminiferans. The type species is the unicellular Reticulomyxa filosa. It is found in freshwater environments as well as moist environments, like decomposing matter and damp soils. The heterotrophic naked foraminiferan can feed on microbes as well has larger organisms and is able to be sustained in culture by supplemented nutrients such as wheat germ and oats. The large, multinucleate foraminferan is characteristic for its lack of test and named for the network of connecting pseudopodia surrounding its central body mass. The organism has unique bidirectional cytoplasmic streaming throughout the anastomosing pseudopodia that is some of the fastest reported organelle transport observed. Reticulomyxa was first described in 1949 and is commonly used as a model organism for the unique transport of organelles throughout the cytoplasm of pseudopodia by cytoskeletal mechanisms. Only asexual reproduction of this genus has been observed in culture, but the genome possesses genes related to meiosis suggesting it is capable of sexually reproductive life stages.

Pandoravirus is a genus of giant virus, first discovered in 2013. It is the second largest in physical size of any known viral genus. Pandoraviruses have double stranded DNA genomes, with the largest genome size of any known viral genus.

<span class="mw-page-title-main">Amoeba</span> Polyphyletic group of unicellular eukaryotes with the ability to shapeshift

An amoeba, often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudopods. Amoebae do not form a single taxonomic group; instead, they are found in every major lineage of eukaryotic organisms. Amoeboid cells occur not only among the protozoa, but also in fungi, algae, and animals.

<i>Vampyrella lateritia</i> Species of protist

Vampyrella lateritia is a freshwater species of predatory amoebae that feeds on species of algae and is known for its specialized feeding strategy of removing, digesting, and ingesting the cellular contents of its prey. It is the type species of the genus Vampyrella and has been identified in numerous locations around the world including Brazil, Germany, and the eastern United States. Along with Vampyrella pendula, its genome was sequenced in 2012.

References

  1. 1 2 Schaeffer, Asa Arthur (1926a). "Taxonomy of the amebas, with descriptions of thirty-nine new marine and freshwater species". Papers from the Department of Marine Biology of the Carnegie Institution of Washington. 24: 115 pp. 12 plates.
  2. 1 2 Schaeffer, Asa A. (1916). "Notes on the specific and other characters of Amoeba proteusPall. (Leidy), A. discoides spec. nov., and A. dubia spec. nov". Archiv für Protistenkunde. 37: 204–228.
  3. Laura Wegener Parfrey; Daniel J G Lahr; Laura A Katz (April 2008). "The dynamic nature of eukaryotic genomes". Molecular Biology and Evolution . 25 (4): 787–94. doi:10.1093/MOLBEV/MSN032. ISSN   0737-4038. PMC   2933061 . PMID   18258610. Wikidata   Q24618570.
  4. 1 2 3 Casey L McGrath; Laura A Katz (1 January 2004). "Genome diversity in microbial eukaryotes". Trends in Ecology & Evolution. 19 (1): 32–38. doi:10.1016/J.TREE.2003.10.007. ISSN   0169-5347. PMID   16701223. Wikidata   Q28240254.
  5. 1 2 3 Lee, J.J.; Hutner, S.H.; Bovee, E.C., eds. (1985). Illustrated Guide to the Protozoa. Lawrence, Kansas: Society of Protozoologists. pp. ix + 630 pages.
  6. 1 2 "Polychaos dubium". micro*scope - version 6.0. Archived from the original on 2010-07-25. Retrieved 2009-10-01.
  7. "Polychaos dubium". Protist Information Server. Retrieved 2009-10-01.
  8. "Polychaos dubium". Amoebae on the Web. Archived from the original on 2003-05-22. Retrieved 2009-10-01.

Further reading