Didinium

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Didinium
040 Didinium nasutum.jpg
Didinium nasutum as illustrated by Schewiakoff, 1896
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Clade: Alveolata
Phylum: Ciliophora
Class: Litostomatea
Order: Haptorida
Family: Didiniidae
Genus: Didinium
Stein, 1859

Didinium is a genus of unicellular ciliates with at least ten accepted species. All are free-living carnivores. Most are found in fresh and brackish water, but three marine species are known. Their diet consists largely of Paramecium , although they will also attack and consume other ciliates. [1] Some species, such as D. gargantua, also feeds on non-ciliate protists, including dinoflagellates, cryptomonads, and green algae. [2]

Contents

Appearance and reproduction

Didinium nasutum CGI illustration by Denis Zarubin, 2021 Didinium nasutum 3D-model.jpg
Didinium nasutum CGI illustration by Denis Zarubin, 2021

Didinia are rounded, oval, or barrel-shaped and range in length from 50 to 150 micrometres. [3] The cell body is encircled by two ciliary bands, or pectinelles, an upper band and a lower band just below the midline. [4] This distinguishes them from the related genus Monodinium , which have only a single band, except during cell division. [5] The pectinelles are used to move Didinium through water by rotating the cell around its axis. [6] At the anterior end, a cone-shaped structure protrudes, supported by a palisade of stiff microtubular rods (nematodesmata). This cone encloses the cytostome, or "mouth" opening, as in other haptorian ciliates. The dimensions of this protuberance vary among the different species.

The macronucleus is long and may be curved, horseshoe-shaped, or twisted into a shape resembling a figure eight. [7] A contractile vacuole and anal aperture are in the posterior of the cell. [8]

Like all ciliates, Didinia reproduces asexually via binary fission or sexually after undergoing conjugation.

Didinium nasutum

Didinium nasutum consuming a Paramecium. Illustration by S. O. Mast, 1909 Didinium nasutum consuming a paramecium.jpg
Didinium nasutum consuming a Paramecium. Illustration by S. O. Mast, 1909

Much of what has been published about this genus is based on numerous studies of a single species, Didinium nasutum. A voracious predator, D. nasutum uses specialized structures called toxicysts to ensnare and paralyze its ciliate prey. Once captured, the prey is engulfed by Didinium's expandible cytostome. [9]

While D. nasutum is sometimes described as feeding exclusively upon Paramecium , it has been shown that the organism will readily devour other ciliate species, including Colpoda , Colpidium campylum, Tetrahymena pyriformis , Coleps hirtus , and Lacrymaria olor . [1] [10] Moreover, strains of Didinium raised on a Colpidium campylum will actually show a preference for a diet made up of that species, as well as a diminished ability to kill and ingest Paramecia. [1]

In the absence of food, D. nasutum will encyst, lying dormant within a protective coating. [11] In the laboratory, other environmental stimuli, such as the age of the growth medium or the accumulation of certain metabolic waste products, can also trigger encystment. [12] When the encysted form of D. nasutum is exposed to a vigorous culture of Paramecium, it will excyst, reverting to its active, swimming form. [13]

Didinium cysts have been shown to remain viable for at least 10 years. [14]

History and classification

Vorticella nasuta, from O. F. Muller, 1786 Vorticella nasuta from Muller.jpg
Vorticella nasuta, from O. F. Müller, 1786

In the 18th century, Didinium was discovered by the naturalist O.F. Müller and described in his Animalcula Infusoria under the name Vorticella nasuta. [15] In 1859, Samuel Friedrich Stein moved the species to the newly created genus Didinium, which he placed within the order Peritricha, alongside other ciliates which have a ciliary fringe at the anterior of the cell, such as Vorticella and Cothurnia. [16] Later in the century, under the taxonomical scheme created by Otto Bütschli, Didinium was removed from among the Peritrichs, and placed in the order Holotricha . [17] In 1974, John O. Corliss created the order Haptorida, within the subclass Haptoria, for "rapacious carnivorous forms" such as Didinium, Dileptus , and Spathidium . [18] This group has since been placed in the class Litostomatea Small & Lynn, 1981.

Genetic analysis of Haptorian ciliates has shown that they do not form a monophyletic group. [19] [20]

List of Species

Didinium alveolatum Kahl, 1930
Didinium armatum Penard, 1922
Didinium balbianii Fabre-Domergue, 1888
Didinium bosphoricum Hovasse, 1932
 Didinium chlorelligerum Kahl, 1935
Didinium faurei Kahl, 1930
Didinium gargantua Meunier, 1910
Didinium impressum Kahl, 1926
Didinium minimum
Didinium nasutum (Müller, 1773) Stein, 1859

Related Research Articles

<span class="mw-page-title-main">Litostomatea</span> Class of single-celled organisms

The Litostomatea are a class of ciliates. The group consists of three subclasses: Haptoria, Trichostomatia and Rhynchostomatia. Haptoria includes mostly carnivorous forms such as Didinium, a species of which preys primarily on the ciliate Paramecium. Trichostomatia (trichostomes) are mostly endosymbionts in the digestive tracts of vertebrates. These include the species Balantidium coli, which is the only ciliate parasitic in humans. The group Rhynchostomatia includes two free-living orders previously included among the Haptoria, but now known to be genetically distinct from them, the Dileptida and the Tracheliida.

<i>Paramecium</i> Genus of unicellular ciliates, commonly studied as a representative of the ciliate group

Paramecium is a genus of eukaryotic, unicellular ciliates, commonly studied as a model organism of the ciliate group. Paramecium are widespread in freshwater, brackish, and marine environments and are often abundant in stagnant basins and ponds. Because some species are readily cultivated and easily induced to conjugate and divide, they have been widely used in classrooms and laboratories to study biological processes. The usefulness of Paramecium as a model organism has caused one ciliate researcher to characterize it as the "white rat" of the phylum Ciliophora.

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

Blepharisma is a genus of unicellular ciliate protists found in fresh and salt water. The group includes about 40 accepted species, and many sub-varieties and strains. While species vary considerably in size and shape, most are easily identified by their red or pinkish color, which is caused by granules of the pigment blepharismin.

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

Balantidium is a genus of ciliates. It contains the parasitic species Balantidium coli, the only known cause of balantidiasis.

<span class="mw-page-title-main">Holotricha</span> Order of single-celled organisms

Holotricha is an order of ciliates. The classification has fallen from use as a formal taxon, but the terms "holotrich" and "holotrichous" are still applied descriptively to organisms with cilia of uniform length distributed evenly over the surface of the body.

Myzocytosis is a method of feeding found in some heterotrophic organisms. It is also called "cellular vampirism" as the predatory cell pierces the cell wall and/or cell membrane of the prey cell with a feeding tube, the conoid, sucks out the cellular content and digests it.

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

Vorticella is a genus of bell-shaped ciliates that have stalks to attach themselves to substrates. The stalks have contractile myonemes, allowing them to pull the cell body against substrates. The formation of the stalk happens after the free-swimming stage.

<span class="mw-page-title-main">Protozoa</span> Single-celled eukaryotic organisms that feed on organic matter

Protozoa are a polyphyletic group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic debris. Historically, protozoans were regarded as "one-celled animals".

<span class="mw-page-title-main">Ciliate</span> Taxon of protozoans with hair-like organelles called cilia

The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to eukaryotic flagella, but are in general shorter and present in much larger numbers, with a different undulating pattern than flagella. Cilia occur in all members of the group and are variously used in swimming, crawling, attachment, feeding, and sensation.

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

Frontonia is a genus of free-living unicellular ciliate protists, belonging to the order Peniculida. As Peniculids, the Frontonia are closely related to members of the genus Paramecium. However, whereas Paramecia are mainly bacterivores, Frontonia are capable of ingesting large prey such as diatoms, filamentous algae, testate amoebas, and even, in some circumstances, members of their own species. In bacteria-rich saprobic conditions, Frontonia leucas can live as a facultative bacterivore.

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

Climacostomum is a genus of unicellular ciliates, belonging to the class Heterotrichea.

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

Dileptus is a genus of unicellular ciliates in the class Litostomatea. Species of Dileptus occur in fresh and salt water, as well as mosses and soils. Most are aggressive predators equipped with long, mobile proboscides lined with toxic extrusomes, with which they stun smaller organisms before consuming them. Thirteen species and subspecies of Dileptus are currently recognized.

<i>Peranema</i> Genus of protozoans

Peranema is a genus of free-living phagotrophic euglenids. There are more than 20 nominal species, varying in size between 8 and 200 micrometers. Peranema cells are gliding flagellates found in freshwater lakes, ponds and ditches, and are often abundant at the bottom of stagnant pools rich in decaying organic material. Although they belong to the class Euglenoidea, and are morphologically similar to the green Euglena, Peranema have no chloroplasts, and do not conduct autotrophy. Instead, they capture live prey, such as yeast, bacteria and other flagellates, consuming them with the help of a rigid feeding apparatus called a "rod-organ." Unlike the green euglenids, they lack both an eyespot (stigma), and the paraflagellar body (photoreceptor) that is normally coupled with that organelle. However, while Peranema lack a localized photoreceptor, they do possess the light-sensitive protein rhodopsin, and respond to changes in light with a characteristic "curling behaviour."

<i>Climacostomum virens</i> Species of single-celled organism

Climacostomum virens is a species of unicellular ciliate protists. It is one of just two formally described species in the genus Climacostomum.

<span class="mw-page-title-main">Mobilida</span> Order of protists belonging to the ciliates phylum

Mobilida is a group of parasitic or symbiotic peritrich ciliates, comprising more than 280 species. Mobilids live on or within a wide variety of aquatic organisms, including fish, amphibians, molluscs, cnidarians, flatworms and other ciliates, attaching to their host organism by means of an aboral adhesive disk. Some mobilid species are pathogens of wild or farmed fish, causing severe and economically damaging diseases such as trichodinosis.

<i>Pseudomonilicaryon anser</i> Species of single-celled organism

Pseudomonilicaryon anser is a species of unicellular ciliates in the family Dileptidae, also known under the names Dileptus anser and Dileptus cygnus. The species is common in fresh water ponds, stagnant pools, mosses and soils.

<span class="mw-page-title-main">Condylostoma</span> Genus of protists belonging to the ciliates phylum

Condylostoma is a genus of unicellular ciliate protists, belonging to the class Heterotrichea.

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

Tracheloraphis is a genus of ciliates in the family Trachelocercidae.

<span class="mw-page-title-main">Stentor roeselii</span> Species of single-celled organism

Stentor roeselii is a free-living ciliate species of the genus Stentor, in the class Heterotrichea. It is a common and widespread protozoan, found throughout the world in freshwater ponds, lakes, rivers and ditches.

Parablepharismea is a class of free-living marine and brackish anaerobic ciliates that form a major clade of obligate anaerobes within the SAL group, together with the classes Muranotrichea and Armophorea.

References

  1. 1 2 3 Berger, Jacques (October 1979). "The Feeding Behavior of Didinium nasutum on an Atypical Prey Ciliate (Colpidium campylum)". Transactions of the American Microscopical Society. 98 (4): 487–94. doi:10.2307/3225898. JSTOR   3225898.
  2. ↑ Kypke, Reinhard. "Didinium gargantua Meunier, 1910". www.zooplankton.cn. Archived from the original on 2016-12-21. Retrieved 2016-12-13.
  3. ↑ Kahl, Alfred (1930–35). F. Dahl (ed.). Urtiere oder Protozoa I: Wimpertiere oder Ciliata (Infusoria) In: Die Tierwelt Deutschlands. Vol. 1. Allgemeiner teil und Prostomata. Jena: G. Fischer. pp. 123–6.
  4. ↑ "Didinium Morphology". www.nies.go.jp. Retrieved 25 October 2019.
  5. ↑ Lee, John J.; et al. (2000). John J. Lee; Gordon F. Leedale; Phyllis Bradbury (eds.). An Illustrated Guide to the Protozoa: organisms traditionally referred to as protozoa, or newly discovered groups. Vol. 1 (2 ed.). Lawrence, Kansas: Society of Protozoologists. pp. 480–1. ISBN   1-891276-22-0.
  6. ↑ Mast 1909 , pp. 92–3
  7. ↑ Mast 1909 , p. 92
  8. ↑ Kent, William Saville (1881–1882). A Manual of the Infusoria. Vol. 2. London: David Bogue. pp. 638–9.
  9. ↑ Mast 1909 , pp. 96–112
  10. ↑ Mast 1909 , p. 114
  11. ↑ Beers, C. Dale (15 Sep 1925). "Encystment and the Life Cycle in the Ciliate Didinium nasutum". Proceedings of the National Academy of Sciences. 11 (9): 525. Bibcode:1925PNAS...11..523B. doi: 10.1073/pnas.11.9.523 . PMC   1086111 . PMID   16576909.
  12. ↑ Beers, C. Dale (March 1927). "Factors involved in encystment in the ciliate didinium nasutum". Journal of Morphology. 43 (2): 499–520. doi:10.1002/jmor.1050430208. S2CID   83902868.
  13. ↑ Mast, S. O. (July 1917). "Conjugation and encystment in Didinium nasutum with especial reference to their significance". Journal of Experimental Zoology. 23 (2): 340. doi:10.1002/jez.1400230206.
  14. ↑ Beers, C. Dale (Sep–Oct 1937). "The Viability of Ten-Year-Old Didinium Cysts (Infusoria)". The American Naturalist. 71 (736): 521–4. doi:10.1086/280739. JSTOR   2457306. S2CID   83784747.
  15. ↑ Müller, O.F. Animalcula Infusoria, Fluvia Tilia et Marina. 1786. Hauniae, Typis N. Mölleri. pp. 268-9.
  16. ↑ Stein, Friedrich (1859). Der Organismus der Infusionsthiere (1859). Leipzig: W. Engelmann.
  17. ↑ Bütschli, Otto (1887–1889). Bronn, H. G. (ed.). ERSTER BAND. PROTOZOA. Vol. III. Leipzig & Heidelberg: C. F. Winter. p. 1688.{{cite book}}: |work= ignored (help)
  18. ↑ Corliss, John O. (May 1974). "Remarks on the Composition of the Large Ciliate Class Kinetofragmophora de Puytorac et al., 1974, and Recognition of Several New Taxa Therein, with Emphasis on the Primitive Order Primociliatida N. Ord". Journal of Eukaryotic Microbiology. 21 (2): 207–220. doi:10.1111/j.1550-7408.1974.tb03643.x.
  19. ↑ Gao, S; et al. (Nov–Dec 2008). "Phylogeny of six genera of the subclass Haptoria (Ciliophora, Litostomatea) inferred from sequences of the gene coding for small subunit ribosomal RNA". Journal of Eukaryotic Microbiology. 55 (6): 562–6. doi:10.1111/j.1550-7408.2008.00360.x. PMID   19120803. S2CID   41417127.
  20. ↑ Vd'ačný, Peter; et al. (May 2011). "Phylogeny and Classification of the Litostomatea (Protista, Ciliophora), with Emphasis on Free-Living Taxa and the 18S rRNA Gene". Mol Phylogenet Evol. 59 (2): 510–22. doi:10.1016/j.ympev.2011.02.016. PMID   21333743.
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