Ciliate

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Ciliate
Temporal range: Ediacaran–Recent
Ciliate collage.jpg
Some examples of ciliate diversity. Clockwise from top left: Lacrymaria , Coleps , Stentor , Dileptus , Paramecium
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Diaphoretickes
Clade: TSAR
Clade: SAR
Clade: Alveolata
Phylum: Ciliophora
Doflein, 1901 emend.
Subphyla and classes [1]

See text for subclasses.

Synonyms
  • Ciliata Perty, 1852

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 (although the peculiar Suctoria only have them for part of their life cycle) and are variously used in swimming, crawling, attachment, feeding, and sensation.

Contents

Ciliates are an important group of protists, common almost anywhere there is water—in lakes, ponds, oceans, rivers, and soils, including anoxic and oxygen-depleted habitats. [2] About 4,500 unique free-living species have been described, and the potential number of extant species is estimated at 27,000–40,000. [3] Included in this number are many ectosymbiotic and endosymbiotic species, as well as some obligate and opportunistic parasites. Ciliate species range in size from as little as 10 μm in some colpodeans to as much as 4 mm in length in some geleiids, and include some of the most morphologically complex protozoans. [4] [5]

In most systems of taxonomy, "Ciliophora" is ranked as a phylum [6] under any of several kingdoms, including Chromista, [7] Protista [8] or Protozoa. [9] In some older systems of classification, such as the influential taxonomic works of Alfred Kahl, ciliated protozoa are placed within the class "Ciliata" [10] [11] (a term which can also refer to a genus of fish). In the taxonomic scheme endorsed by the International Society of Protistologists, which eliminates formal rank designations such as "phylum" and "class", "Ciliophora" is an unranked taxon within Alveolata. [12] [13]

Cell structure

Nuclei

Unlike most other eukaryotes, ciliates have two different sorts of nuclei: a tiny, diploid micronucleus (the "generative nucleus", which carries the germline of the cell), and a large, ampliploid macronucleus (the "vegetative nucleus", which takes care of general cell regulation, expressing the phenotype of the organism). [14] [15] The latter is generated from the micronucleus by amplification of the genome and heavy editing. The micronucleus passes its genetic material to offspring, but does not express its genes. The macronucleus provides the small nuclear RNA for vegetative growth. [16] [15]

Division of the macronucleus occurs in most ciliate species, apart from those in class Karyorelictea, whose macronuclei are replaced every time the cell divides. [17] Macronuclear division is accomplished by amitosis, and the segregation of the chromosomes occurs by a process whose mechanism is unknown. [15] After a certain number of generations (200–350, in Paramecium aurelia, and as many as 1,500 in Tetrahymena [17] ) the cell shows signs of aging, and the macronuclei must be regenerated from the micronuclei. Usually, this occurs following conjugation , after which a new macronucleus is generated from the post-conjugal micronucleus. [15]

Representation of a ciliate Cilia Trichocyst Alveoli, surface cavities or pits Contractile vacuole, regulates the quantity of water inside a cell Contractile vacuole pore Radial canal Food vacuoles Lysosome, holds enzymes Golgi apparatus; modifies proteins and sends them out of the cell Micronucleus Macronucleus, controls non-reproductive cell functions Vestibulum Buccal cavity Quadrulus Cytostome, cell mouth Nascent food vacuole Acidosome, vesicle involved in the acidification of phagocytes Waste vacuole Cytoproct, anal pore for waste ejection Endoplasmic reticulum, the transport network for molecules going to specific parts of the cell Mitochondrion, creates ATP (energy) for the cell (tubularcristae) Endosymbionts 2023 Ciliate.svg
Representation of a ciliate
  1. Cilia
  2. Trichocyst
  3. Alveoli, surface cavities or pits
  4. Contractile vacuole, regulates the quantity of water inside a cell
  5. Contractile vacuole pore
  6. Radial canal
  7. Food vacuoles
  8. Lysosome, holds enzymes
  9. Golgi apparatus; modifies proteins and sends them out of the cell
  10. Micronucleus
  11. Macronucleus, controls non-reproductive cell functions
  12. Vestibulum
  13. Buccal cavity
  14. Quadrulus
  15. Cytostome, cell mouth
  16. Nascent food vacuole
  17. Acidosome, vesicle involved in the acidification of phagocytes
  18. Waste vacuole
  19. Cytoproct, anal pore for waste ejection
  20. Endoplasmic reticulum, the transport network for molecules going to specific parts of the cell
  21. Mitochondrion, creates ATP (energy) for the cell (tubularcristae)
  22. Endosymbionts

Cytoplasm

Food vacuoles are formed through phagocytosis and typically follow a particular path through the cell as their contents are digested and broken down by lysosomes so the substances the vacuole contains are then small enough to diffuse through the membrane of the food vacuole into the cell. Anything left in the food vacuole by the time it reaches the cytoproct (anal pore) is discharged by exocytosis. Most ciliates also have one or more prominent contractile vacuoles, which collect water and expel it from the cell to maintain osmotic pressure, or in some function to maintain ionic balance. In some genera, such as Paramecium , these have a distinctive star shape, with each point being a collecting tube.

Specialized structures in ciliates

Mostly, body cilia are arranged in mono- and dikinetids , which respectively include one and two kinetosomes (basal bodies), each of which may support a cilium. These are arranged into rows called kineties, which run from the anterior to posterior of the cell. The body and oral kinetids make up the infraciliature, an organization unique to the ciliates and important in their classification, and include various fibrils and microtubules involved in coordinating the cilia. In some forms there are also body polykinetids, for instance, among the spirotrichs where they generally form bristles called cirri.

The infraciliature is one of the main components of the cell cortex. Others are the alveoli, small vesicles under the cell membrane that are packed against it to form a pellicle maintaining the cell's shape, which varies from flexible and contractile to rigid. Numerous mitochondria and extrusomes are also generally present. The presence of alveoli, the structure of the cilia, the form of mitosis and various other details indicate a close relationship between the ciliates, Apicomplexa, and dinoflagellates. These superficially dissimilar groups make up the alveolates.

Feeding

Most ciliates are heterotrophs, feeding on smaller organisms, such as bacteria and algae, and detritus swept into the oral groove (mouth) by modified oral cilia. This usually includes a series of membranelles to the left of the mouth and a paroral membrane to its right, both of which arise from polykinetids, groups of many cilia together with associated structures. The food is moved by the cilia through the mouth pore into the gullet, which forms food vacuoles.

Many species are also mixotrophic, combining phagotrophy and phototrophy through kleptoplasty or symbiosis with photosynthetic microbes. [18] [19]

The ciliate Halteria has been observed to feed on chloroviruses. [20]

Feeding techniques vary considerably, however. Some ciliates are mouthless and feed by absorption (osmotrophy), while others are predatory and feed on other protozoa and in particular on other ciliates. Some ciliates parasitize animals, although only one species, Balantidium coli , is known to cause disease in humans. [21]

Reproduction and sexual phenomena

Most ciliates divide transversally, but other kinds of binary fission occur in some species. Some types of ciliate fission.svg
Most ciliates divide transversally, but other kinds of binary fission occur in some species.

Reproduction

Ciliates reproduce asexually, by various kinds of fission. [17] During fission, the micronucleus undergoes mitosis and the macronucleus elongates and undergoes amitosis (except among the Karyorelictean ciliates, whose macronuclei do not divide). The cell then divides in two, and each new cell obtains a copy of the micronucleus and the macronucleus.

Ciliate undergoing the last processes of binary fission Unk.cilliate.jpg
Ciliate undergoing the last processes of binary fission
Division of ciliate Colpidium

Typically, the cell is divided transversally, with the anterior half of the ciliate (the proter) forming one new organism, and the posterior half (the opisthe) forming another. However, other types of fission occur in some ciliate groups. These include budding (the emergence of small ciliated offspring, or "swarmers", from the body of a mature parent); strobilation (multiple divisions along the cell body, producing a chain of new organisms); and palintomy (multiple fissions, usually within a cyst). [22]

Fission may occur spontaneously, as part of the vegetative cell cycle. Alternatively, it may proceed as a result of self-fertilization (autogamy), [23] or it may follow conjugation, a sexual phenomenon in which ciliates of compatible mating types exchange genetic material. While conjugation is sometimes described as a form of reproduction, it is not directly connected with reproductive processes, and does not directly result in an increase in the number of individual ciliates or their progeny. [24]

Conjugation

Overview

Ciliate conjugation is a sexual phenomenon that results in genetic recombination and nuclear reorganization within the cell. [24] [22] During conjugation, two ciliates of a compatible mating type form a bridge between their cytoplasms. The micronuclei undergo meiosis, the macronuclei disappear, and haploid micronuclei are exchanged over the bridge. In some ciliates (peritrichs, chonotrichs and some suctorians), conjugating cells become permanently fused, and one conjugant is absorbed by the other. [21] [25] In most ciliate groups, however, the cells separate after conjugation, and both form new macronuclei from their micronuclei. [26] Conjugation and autogamy are always followed by fission. [22]

In many ciliates, such as Paramecium, conjugating partners (gamonts) are similar or indistinguishable in size and shape. This is referred to as "isogamontic" conjugation. In some groups, partners are different in size and shape. This is referred to as "anisogamontic" conjugation. In sessile peritrichs, for instance, one sexual partner (the microconjugant) is small and mobile, while the other (macroconjugant) is large and sessile. [24]

Stages of conjugation
Stages of conjugation in Paramecium caudatum Stages of ciliate conjugation.svg
Stages of conjugation in Paramecium caudatum

In Paramecium caudatum , the stages of conjugation are as follows (see diagram at right):

  1. Compatible mating strains meet and partly fuse
  2. The micronuclei undergo meiosis, producing four haploid micronuclei per cell.
  3. Three of these micronuclei disintegrate. The fourth undergoes mitosis.
  4. The two cells exchange a micronucleus.
  5. The cells then separate.
  6. The micronuclei in each cell fuse, forming a diploid micronucleus.
  7. Mitosis occurs three times, giving rise to eight micronuclei.
  8. Four of the new micronuclei transform into macronuclei, and the old macronucleus disintegrates.
  9. Binary fission occurs twice, yielding four identical daughter cells.

DNA rearrangements (gene scrambling)

Ciliates contain two types of nuclei: somatic "macronucleus" and the germline "micronucleus". Only the DNA in the micronucleus is passed on during sexual reproduction (conjugation). On the other hand, only the DNA in the macronucleus is actively expressed and results in the phenotype of the organism. Macronuclear DNA is derived from micronuclear DNA by amazingly extensive DNA rearrangement and amplification.

Development of the Oxytricha macronuclear genome from micronuclear genome Development of the Oxytricha macronuclear genome.jpg
Development of the Oxytricha macronuclear genome from micronuclear genome

The macronucleus begins as a copy of the micronucleus. The micronuclear chromosomes are fragmented into many smaller pieces and amplified to give many copies. The resulting macronuclear chromosomes often contain only a single gene. In Tetrahymena , the micronucleus has 10 chromosomes (five per haploid genome), while the macronucleus has over 20,000 chromosomes. [27]

In addition, the micronuclear genes are interrupted by numerous "internal eliminated sequences" (IESs). During development of the macronucleus, IESs are deleted and the remaining gene segments, macronuclear destined sequences (MDSs), are spliced together to give the operational gene. Tetrahymena has about 6,000 IESs and about 15% of micronuclear DNA is eliminated during this process. The process is guided by small RNAs and epigenetic chromatin marks. [27]

In spirotrich ciliates (such as Oxytricha ), the process is even more complex due to "gene scrambling": the MDSs in the micronucleus are often in different order and orientation from that in the macronuclear gene, and so in addition to deletion, DNA inversion and translocation are required for "unscrambling". This process is guided by long RNAs derived from the parental macronucleus. More than 95% of micronuclear DNA is eliminated during spirotrich macronuclear development. [27]

Aging

ln clonal populations of Paramecium, aging occurs over successive generations leading to a gradual loss of vitality, unless the cell line is revitalized by conjugation or autogamy. In Paramecium tetraurelia, the clonally aging line loses vitality and expires after about 200 fissions, if the cell line is not rejuvenated by conjugation or self-fertilization. The basis for clonal aging was clarified by the transplantation experiments of Aufderheide in 1986 [28] who demonstrated that the macronucleus, rather than the cytoplasm, is responsible for clonal aging. Additional experiments by Smith-Sonneborn, [29] Holmes and Holmes, [30] and Gilley and Blackburn [31] demonstrated that, during clonal aging, DNA damage increases dramatically. Thus, DNA damage appears to be the cause of aging in P. tetraurelia.

Fossil record

Until recently, the oldest ciliate fossils known were tintinnids from the Ordovician period. In 2007, Li et al. published a description of fossil ciliates from the Doushantuo Formation, about 580 million years ago, in the Ediacaran period. These included two types of tintinnids and a possible ancestral suctorian. [32] A fossil Vorticella has been discovered inside a leech cocoon from the Triassic period, about 200 million years ago. [33]

Phylogeny

According to the 2016 phylogenetic analysis, [1] Mesodiniea is consistently found as the sister group to all other ciliates. Additionally, two big sub-groups are distinguished inside subphylum Intramacronucleata: SAL (Spirotrichea+Armophorea+Litostomatea) and CONthreeP or Ventrata (Colpodea+Oligohymenophorea+Nassophorea+Phyllopharyngea+Plagiopylea+Prostomatea). [1] The class Protocruziea is found as the sister group to Ventrata/CONthreeP. The class Cariacotrichea was excluded from the analysis, but it was originally established as part of Intramacronucleata [1] .
The odontostomatids were identified in 2018 [34] as its own class Odontostomatea, related to Armophorea.

Ciliophora

Classification

Stentor roeselii Stentor roeseli composite image.jpg
Stentor roeselii

Several different classification schemes have been proposed for the ciliates. The following scheme is based on a molecular phylogenetic analysis of up to four genes from 152 species representing 110 families: [1]

Subphylum Postciliodesmatophora

Subphylum Intramacronucleata

Oxytricha trifallax Oxytricha trifallax.jpg
Oxytricha trifallax

Other

Some old classifications included Opalinidae in the ciliates. The fundamental difference between multiciliate flagellates (e.g., hemimastigids, Stephanopogon , Multicilia , opalines) and ciliates is the presence of macronuclei in ciliates alone. [35]

Pathogenicity

The only member of the ciliate phylum known to be pathogenic to humans is Balantidium coli , [36] which causes the disease balantidiasis. It is not pathogenic to the domestic pig, the primary reservoir of this pathogen. [37]

Related Research Articles

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

Tetrahymena is a genus of free-living ciliates, examples of unicellular eukaryotes. The genus Tetrahymena is the most widely studied member of its phylum. It can produce, store and react with different types of hormones. Tetrahymena cells can recognize both related and hostile cells.

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

Paramecium is a genus of eukaryotic, unicellular ciliates, widespread in freshwater, brackish, and marine environments. Paramecia 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. Paramecium species are commonly studied as model organisms of the ciliate group and have been characterized as the "white rats" of the phylum Ciliophora.

Tracy Morton Sonneborn was an American biologist. His life's study was ciliated protozoa of the group Paramecium.

<i>Stentor</i> (ciliate) Genus of single-celled organisms

Stentor, sometimes called trumpet animalcules, are a genus of filter-feeding, heterotrophic ciliates, representative of the heterotrichs. They are usually horn-shaped, and reach lengths of two millimeters; as such, they are among the largest known extant unicellular organisms. They reproduce asexually through binary fission.

A macronucleus is the larger type of nucleus in ciliates. Macronuclei are polyploid and undergo direct division without mitosis. It controls the non-reproductive cell functions, such as metabolism. During conjugation, the macronucleus disintegrates, and a new one is formed by karyogamy of the micronuclei.

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

Nuclear dimorphism is a term referred to the special characteristic of having two different kinds of nuclei in a cell. There are many differences between the types of nuclei. This feature is observed in protozoan ciliates, like Tetrahymena, and some foraminifera. Ciliates contain two nucleus types: a macronucleus that is primarily used to control metabolism, and a micronucleus which performs reproductive functions and generates the macronucleus. The compositions of the nuclear pore complexes help determine the properties of the macronucleus and micronucleus. Nuclear dimorphism is subject to complex epigenetic controls. Nuclear dimorphism is continuously being studied to understand exactly how the mechanism works and how it is beneficial to cells. Learning about nuclear dimorphism is beneficial to understanding old eukaryotic mechanisms that have been preserved within these unicellular organisms but did not evolve into multicellular eukaryotes.

Microbial genetics is a subject area within microbiology and genetic engineering. Microbial genetics studies microorganisms for different purposes. The microorganisms that are observed are bacteria and archaea. Some fungi and protozoa are also subjects used to study in this field. The studies of microorganisms involve studies of genotype and expression system. Genotypes are the inherited compositions of an organism. Genetic Engineering is a field of work and study within microbial genetics. The usage of recombinant DNA technology is a process of this work. The process involves creating recombinant DNA molecules through manipulating a DNA sequence. That DNA created is then in contact with a host organism. Cloning is also an example of genetic engineering.

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

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. Some species, such as D. gargantua, also feeds on non-ciliate protists, including dinoflagellates, cryptomonads, and green algae.

<i>Spirostomum</i> Genus of ciliated protists

Spirostomum is a genus of ciliated protists in the class Heterotrichea. It is known for being very contractile. Having been first identified by Christian Gottfried Ehrenberg in 1834, further research has identified eight additional true morphospecies. This bacterivore genus mainly lives in the sediment deposits at the bottom of various aquatic habitats, and members possess rquA genes that could be responsible for their ability to survive in these hypoxic and anoxic environments. They are identifiable by their relatively large tubular/flat vermiform bodies. Their life cycle consists of a growth stage, in which they mature, and asexual and sexual reproduction stages. Some species are model organisms for studies on human pathogenic bacteria, while others are sensitive and accurate bioindicators for toxic substances.

<i>Paramecium caudatum</i> Species of single-celled organism

Paramecium caudatum is a species of unicellular protist in the phylum Ciliophora. They can reach 0.33 mm in length and are covered with minute hair-like organelles called cilia. The cilia are used in locomotion and feeding. The species is very common, and widespread in marine, brackish and freshwater environments.

<span class="mw-page-title-main">Protozoa</span> Single-celled eukaryotic organisms

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".

Karyorelictea is a class of ciliates in the subphylum Postciliodesmatophora. Most species are members of the microbenthos community, that is, microscopic organisms found in the marine interstitial habitat, though one genus, Loxodes, is found in freshwater.

<i>Paramecium aurelia</i> Species of single-celled organism

Paramecium aurelia are unicellular organisms belonging to the genus Paramecium of the phylum Ciliophora. They are covered in cilia which help in movement and feeding.Paramecium can reproduce sexually, asexually, or by the process of endomixis. Paramecium aurelia demonstrate a strong "sex reaction" whereby groups of individuals will cluster together, and emerge in conjugant pairs. This pairing can last up to 12 hours, during which the micronucleus of each organism will be exchanged. In Paramecium aurelia, a cryptic species complex was discovered by observation. Since then, some have tried to decode this complex using genetic data.

<i>Chilodonella uncinata</i> Species of single-celled organism

Chilodonella uncinata is a single-celled organism of the ciliate class of alveoles. As a ciliate, C. uncinata has cilia covering its body and a dual nuclear structure, the micronucleus and macronucleus. Unlike some other ciliates, C. uncinata contains millions of minichromosomes in its macronucleus while its micronucleus is estimated to contain 3 chromosomes. Childonella uncinata is the causative agent of Chilodonelloza, a disease that affects the gills and skin of fresh water fish, and may act as a facultative of mosquito larva.

<i>Sterkiella histriomuscorum</i> Species of single-celled organism

Sterkiella histriomuscorum, formerly Oxytricha trifallax, is a ciliate species in the genus Sterkiella, known for its highly fragmented genomes which have been used as a model for ciliate genetics.

<i>Colpidium colpoda</i> Species of protozoan

Colpidium colpoda are free-living ciliates commonly found in many freshwater environments including streams, rivers, lakes and ponds across the world. Colpidium colpoda is also frequently found inhabiting wastewater treatment plants. This species is used as an indicator of water quality and waste treatment plant performance.

Autogamy or self-fertilization refers to the fusion of two gametes that come from one individual. Autogamy is predominantly observed in the form of self-pollination, a reproductive mechanism employed by many flowering plants. However, species of protists have also been observed using autogamy as a means of reproduction. Flowering plants engage in autogamy regularly, while the protists that engage in autogamy only do so in stressful environments.

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

Intramacronucleata is a subphylum of ciliates. The group is characterized by the manner in which division of the macronucleus is accomplished during binary fission of the cell. In ciliates of this subphylum, division of the macronucleus is achieved by the action of microtubules which are assembled inside the macronucleus itself. This is in contrast to heterotrich ciliates of the subphylum Postciliodesmatophora, in which division of the macronucleus relies on microtubules formed outside the macronuclear envelope.

Gene amplification in Paramecium tetraurelia is an example of gene amplification that has occurred in the unicellular organism Paramecium tetraurelia.

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

Halteria, sometimes referred to as the jumping oligotrich, is a genus of common planktonic ciliates that are found in many freshwater environments. Halteria are easy to locate due to their abundance and distinctive behaviour with observations of Halteria potentially dating back to the 17th century and the discovery of microorganisms. Over time more has been established about their morphology and behavior, which has led to many changes in terms of classification.

References

  1. 1 2 3 4 5 Gao, Feng; Warren, Alan; Zhang, Qianqian; Gong, Jun; Miao, Miao; Sun, Ping; Xu, Dapeng; Huang, Jie; Yi, Zhenzhen (2016-04-29). "The All-Data-Based Evolutionary Hypothesis of Ciliated Protists with a Revised Classification of the Phylum Ciliophora (Eukaryota, Alveolata)". Scientific Reports. 6: 24874. Bibcode:2016NatSR...624874G. doi:10.1038/srep24874. ISSN   2045-2322. PMC   4850378 . PMID   27126745.
  2. ↑ Rotterová, J.; Edgcomb, V. P.; Čepička, I.; Beinart, R. (2022). "Anaerobic ciliates as a model group for studying symbioses in oxygen-depleted environments". The Journal of Eukaryotic Microbiology. 69 (5): e12912. doi:10.1111/jeu.12912. PMID   35325496. S2CID   247677842.
  3. ↑ Foissner, W.; Hawksworth, David, eds. (2009). Protist Diversity and Geographical Distribution. Topics in Biodiversity and Conservation. Vol. 8. Springer Netherlands. p. 111. doi:10.1007/978-90-481-2801-3. ISBN   9789048128006.
  4. ↑ Nielsen, Torkel Gissel; Kiørboe, Thomas (1994). "Regulation of zooplankton biomass and production in a temperate, coastal ecosystem. 2. Ciliates". Limnology and Oceanography. 39 (3): 508–519. Bibcode:1994LimOc..39..508N. doi: 10.4319/lo.1994.39.3.0508 .
  5. ↑ Lynn, Denis (2008). The Ciliated Protozoa 3rd Edition . Springer. pp.  129. ISBN   978-1-4020-8238-2.
  6. ↑ "ITIS Report". Integrated Taxonomic Information System. Retrieved 11 December 2014.
  7. ↑ Cavalier-Smith, Thomas (2018-01-01). "Kingdom Chromista and its eight phyla: a new synthesis emphasising periplastid protein targeting, cytoskeletal and periplastid evolution, and ancient divergences". Protoplasma. 255 (1): 297–357. doi:10.1007/s00709-017-1147-3. ISSN   1615-6102. PMC   5756292 . PMID   28875267.
  8. ↑ Yi Z, Song W, Clamp JC, Chen Z, Gao S, Zhang Q (December 2008). "Reconsideration of systematic relationships within the order Euplotida (Protista, Ciliophora) using new sequences of the gene coding for small-subunit rRNA and testing the use of combined data sets to construct phylogenies of the Diophrys-complex". Mol. Phylogenet. Evol. 50 (3): 599–607. doi:10.1016/j.ympev.2008.12.006. PMID   19121402.
  9. ↑ Miao M, Song W, Chen Z, et al. (2007). "A unique euplotid ciliate, Gastrocirrhus (Protozoa, Ciliophora): assessment of its phylogenetic position inferred from the small subunit rRNA gene sequence". J. Eukaryot. Microbiol. 54 (4): 371–8. doi:10.1111/j.1550-7408.2007.00271.x. PMID   17669163. S2CID   25977768.
  10. ↑ Alfred Kahl (1930). Urtiere oder Protozoa I: Wimpertiere oder Ciliata -- Volume I General Section And Prostomata.
  11. ↑ "Medical Definition of CILIATA". www.merriam-webster.com. Retrieved 2017-12-22.
  12. ↑ Adl, Sina M.; Bass, David; Lane, Christopher E.; Lukeš, Julius; Schoch, Conrad L.; Smirnov, Alexey; Agatha, Sabine; Berney, Cedric; Brown, Matthew W.; Burki, Fabien; Cárdenas, Paco (2019). "Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes". Journal of Eukaryotic Microbiology. 66 (1): 4–119. doi:10.1111/jeu.12691. ISSN   1550-7408. PMC   6492006 . PMID   30257078.
  13. ↑ Adl, Sina M.; et al. (2005). "The new higher level classification of eukaryotes with emphasis on the taxonomy of protists". Journal of Eukaryotic Microbiology. 52 (5): 399–451. doi: 10.1111/j.1550-7408.2005.00053.x . PMID   16248873.
  14. ↑ Raikov, I.B. (1969). "The Macronucleus of Ciliates". Research in Protozoology. 3: 4–115. ISBN   9781483186146.
  15. 1 2 3 4 Archibald, John M.; Simpson, Alastair G. B.; Slamovits, Claudio H., eds. (2017). Handbook of the Protists (2 ed.). Springer International Publishing. p. 691. ISBN   978-3-319-28147-6.
  16. ↑ Prescott, D M (June 1994). "The DNA of ciliated protozoa". Microbiological Reviews. 58 (2): 233–267. doi:10.1128/mr.58.2.233-267.1994. ISSN   0146-0749. PMC   372963 . PMID   8078435.
  17. 1 2 3 H., Lynn, Denis (2008). The ciliated protozoa: characterization, classification, and guide to the literature. New York: Springer. p. 324. ISBN   9781402082382. OCLC   272311632.{{cite book}}: CS1 maint: multiple names: authors list (link)
  18. ↑ Esteban, G. F.; Fenchel, T.; Finlay, B. J. (2010). "Mixotrophy in ciliates". Protist. 161 (5): 621–641. doi:10.1016/j.protis.2010.08.002. PMID   20970377.
  19. ↑ Altenburger, A.; Blossom, H. E.; Garcia-Cuetos, L.; Jakobsen, H. H.; Carstensen, J.; Lundholm, N.; Hansen, P. J.; Haraguchi, L.; Haraguchi, L. (2020). "Dimorphism in cryptophytes-The case of Teleaulax amphioxeia/Plagioselmis prolonga and its ecological implications". Science Advances. 6 (37). Bibcode:2020SciA....6.1611A. doi:10.1126/sciadv.abb1611. PMC   7486100 . PMID   32917704.
  20. ↑ DeLong, John P.; Van Etten, James L.; Al-Ameeli, Zeina; Agarkova, Irina V.; Dunigan, David D. (2023-01-03). "The consumption of viruses returns energy to food chains". Proceedings of the National Academy of Sciences. 120 (1): e2215000120. Bibcode:2023PNAS..12015000D. doi: 10.1073/pnas.2215000120 . PMC   9910503 . PMID   36574690.
  21. 1 2 Lynn, Denis (2008). The Ciliated Protozoa: Characterization, Classification, and Guide to the Literature (3 ed.). Springer. pp.  58. ISBN   978-1-4020-8238-2. 1007/978-1-4020-8239-9
  22. 1 2 3 H., Lynn, Denis (2008). The ciliated protozoa: characterization, classification, and guide to the literature. New York: Springer. p. 23. ISBN   9781402082382. OCLC   272311632.{{cite book}}: CS1 maint: multiple names: authors list (link)
  23. ↑ Berger JD (October 1986). "Autogamy in Paramecium. Cell cycle stage-specific commitment to meiosis". Exp. Cell Res. 166 (2): 475–85. doi:10.1016/0014-4827(86)90492-1. PMID   3743667.
  24. 1 2 3 Raikov, I.B (1972). "Nuclear phenomena during conjugation and autogamy in ciliates". Research in Protozoology. 4: 149.
  25. ↑ Finley, Harold E. "The conjugation of Vorticella microstoma." Transactions of the American Microscopical Society (1943): 97-121.
  26. ↑ "Introduction to the Ciliata" . Retrieved 2009-01-16.
  27. 1 2 3 Mochizuki, Kazufumi (2010). "DNA rearrangements directed by non-coding RNAs in ciliates". Wiley Interdisciplinary Reviews: RNA. 1 (3): 376–387. doi:10.1002/wrna.34. PMC   3746294 . PMID   21956937.
  28. ↑ Aufderheide, Karl J. (1986). "Clonal aging in Paramecium tetraurelia. II. Evidence of functional changes in the macronucleus with age". Mechanisms of Ageing and Development. 37 (3): 265–279. doi:10.1016/0047-6374(86)90044-8. PMID   3553762. S2CID   28320562.
  29. ↑ Smith-Sonneborn, J. (1979). "DNA repair and longevity assurance in Paramecium tetraurelia". Science . 203 (4385): 1115–1117. Bibcode:1979Sci...203.1115S. doi:10.1126/science.424739. PMID   424739.
  30. ↑ Holmes, George E.; Holmes, Norreen R. (July 1986). "Accumulation of DNA damages in aging Paramecium tetraurelia". Molecular and General Genetics. 204 (1): 108–114. doi:10.1007/bf00330196. PMID   3091993. S2CID   11992591.
  31. ↑ Gilley, David; Blackburn, Elizabeth H. (1994). "Lack of telomere shortening during senescence in Paramecium" (PDF). Proceedings of the National Academy of Sciences of the United States of America . 91 (5): 1955–1958. Bibcode:1994PNAS...91.1955G. doi: 10.1073/pnas.91.5.1955 . PMC   43283 . PMID   8127914.
  32. ↑ Li, C.-W.; et al. (2007). "Ciliated protozoans from the Precambrian Doushantuo Formation, Wengan, South China". Geological Society, London, Special Publications. 286 (1): 151–156. Bibcode:2007GSLSP.286..151L. doi:10.1144/SP286.11. S2CID   129584945.
  33. ↑ Bomfleur, Benjamin; Kerp, Hans; Taylor, Thomas N.; Moestrup, Øjvind; Taylor, Edith L. (2012-12-18). "Triassic leech cocoon from Antarctica contains fossil bell animal". Proceedings of the National Academy of Sciences of the United States of America. 109 (51): 20971–20974. Bibcode:2012PNAS..10920971B. doi: 10.1073/pnas.1218879109 . ISSN   1091-6490. PMC   3529092 . PMID   23213234.
  34. 1 2 Fernandes, Noemi M.; Vizzoni, Vinicius F.; Borges, Bárbara do N.; Soares, Carlos A.G.; da Silva-Neto, Inácio D.; Paiva, Thiago da S. (2018), "Molecular phylogeny and comparative morphology indicate that odontostomatids (Alveolata, Ciliophora) form a distinct class-level taxon related to Armophorea", Molecular Phylogenetics and Evolution, 126: 382–389, doi:10.1016/j.ympev.2018.04.026, ISSN   1055-7903, PMID   29679715, S2CID   5032558
  35. ↑ Cavalier-Smith, T. (2000). Flagellate megaevolution: the basis for eukaryote diversification. In: Leadbeater, B.S.C., Green, J.C. (eds.). The Flagellates. Unity, diversity and evolution. London: Taylor and Francis, pp. 361-390, p. 362, .
  36. ↑ "Balantidiasis". DPDx — Laboratory Identification of Parasitic Diseases of Public Health Concern. Centers for Disease Control and Prevention. 2013.
  37. ↑ Schister, Frederick L. and Lynn Ramirez-Avila (October 2008). "Current World Status of Balantidium coli". Clinical Microbiology Reviews. 21 (4): 626–638. doi:10.1128/CMR.00021-08. PMC   2570149 . PMID   18854484.

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