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Rataj M, Vďačný P. Putative ITS2 secondary structure model and multi‐gene phylogenies of tetrahymenids (Ciliophora, Hymenostomatia) parasitizing planarians and crayfish worms. ZOOL SCR 2022. [DOI: 10.1111/zsc.12528] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Matej Rataj
- Department of Zoology Faculty of Natural Sciences Comenius University in Bratislava Bratislava Slovakia
| | - Peter Vďačný
- Department of Zoology Faculty of Natural Sciences Comenius University in Bratislava Bratislava Slovakia
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Doerder FP. Barcodes Reveal 48 New Species of Tetrahymena
, Dexiostoma
, and Glaucoma
: Phylogeny, Ecology, and Biogeography of New and Established Species. J Eukaryot Microbiol 2018; 66:182-208. [DOI: 10.1111/jeu.12642] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 04/30/2018] [Accepted: 05/21/2018] [Indexed: 11/28/2022]
Affiliation(s)
- F. Paul Doerder
- Department of Biological, Geological and Environmental Sciences; Cleveland State University; 2121 Euclid Avenue Cleveland Ohio 44115
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Bohatová M, Vďačný P. Locomotory behaviour of two phylogenetically distant predatory ciliates: does evolutionary history matter? ETHOL ECOL EVOL 2017. [DOI: 10.1080/03949370.2017.1342697] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Michaela Bohatová
- Department of Zoology, Comenius University in Bratislava, 842 15 Bratislava, Slovak Republic
| | - Peter Vďačný
- Department of Zoology, Comenius University in Bratislava, 842 15 Bratislava, Slovak Republic
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Pitsch G, Adamec L, Dirren S, Nitsche F, Šimek K, Sirová D, Posch T. The Green Tetrahymena utriculariae n. sp. (Ciliophora, Oligohymenophorea) with Its Endosymbiotic Algae (Micractinium sp.), Living in Traps of a Carnivorous Aquatic Plant. J Eukaryot Microbiol 2016; 64:322-335. [PMID: 27613221 DOI: 10.1111/jeu.12369] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 09/05/2016] [Accepted: 09/05/2016] [Indexed: 11/30/2022]
Abstract
The genus Tetrahymena (Ciliophora, Oligohymenophorea) probably represents the best studied ciliate genus. At present, more than forty species have been described. All are colorless, i.e. they do not harbor symbiotic algae, and as aerobes they need at least microaerobic habitats. Here, we present the morphological and molecular description of the first green representative, Tetrahymena utriculariae n. sp., living in symbiosis with endosymbiotic algae identified as Micractinium sp. (Chlorophyta). The full life cycle of the ciliate species is documented, including trophonts and theronts, conjugating cells, resting cysts and dividers. This species has been discovered in an exotic habitat, namely in traps of the carnivorous aquatic plant Utricularia reflexa (originating from Okavango Delta, Botswana). Green ciliates live as commensals of the plant in this anoxic habitat. Ciliates are bacterivorous, however, symbiosis with algae is needed to satisfy cell metabolism but also to gain oxygen from symbionts. When ciliates are cultivated outside their natural habitat under aerobic conditions and fed with saturating bacterial food, they gradually become aposymbiotic. Based on phylogenetic analyses of 18S rRNA and mitochondrial cox1 genes T. utriculariae forms a sister group to Tetrahymena thermophila.
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Affiliation(s)
- Gianna Pitsch
- Limnological Station, Department of Plant and Microbial Biology, University of Zurich, Kilchberg, 8802, Switzerland
| | - Lubomír Adamec
- Institute of Botany CAS, Section of Plant Ecology, Třeboň, 379 82, Czech Republic
| | - Sebastian Dirren
- Limnological Station, Department of Plant and Microbial Biology, University of Zurich, Kilchberg, 8802, Switzerland
| | - Frank Nitsche
- Institute for Zoology, General Ecology, Biocenter, University of Cologne, Cologne, 50674, Germany
| | - Karel Šimek
- Biology Centre CAS, Institute of Hydrobiology, České Budějovice, 370 05, Czech Republic
| | - Dagmara Sirová
- Biology Centre CAS, Institute of Hydrobiology, České Budějovice, 370 05, Czech Republic.,Faculty of Science, University of South Bohemia, České Budějovice, 370 05, Czech Republic
| | - Thomas Posch
- Limnological Station, Department of Plant and Microbial Biology, University of Zurich, Kilchberg, 8802, Switzerland
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Liu M, Fan X, Gao F, Gao S, Yu Y, Warren A, Huang J. Tetrahymena australis
(Protozoa, Ciliophora): A Well-Known But “Non-Existing” Taxon - Consideration of Its Identification, Definition and Systematic Position. J Eukaryot Microbiol 2016; 63:760-770. [DOI: 10.1111/jeu.12323] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 04/01/2016] [Accepted: 04/18/2016] [Indexed: 01/17/2023]
Affiliation(s)
- Mingjian Liu
- Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences; Institute of Hydrobiology; Chinese Academy of Sciences; Wuhan 430072 China
- Institute of Evolution & Marine Biodiversity; Ocean University of China; Qingdao 266003 China
| | - Xinpeng Fan
- School of Life Sciences; East China Normal University; Shanghai 200241 China
| | - Feng Gao
- Institute of Evolution & Marine Biodiversity; Ocean University of China; Qingdao 266003 China
| | - Shan Gao
- Institute of Evolution & Marine Biodiversity; Ocean University of China; Qingdao 266003 China
| | - Yuhe Yu
- Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences; Institute of Hydrobiology; Chinese Academy of Sciences; Wuhan 430072 China
| | - Alan Warren
- Department of Life Sciences; Natural History Museum; Cromwell Road London SW7 5BD United Kingdom
| | - Jie Huang
- Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences; Institute of Hydrobiology; Chinese Academy of Sciences; Wuhan 430072 China
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Doerder FP. Abandoning sex: multiple origins of asexuality in the ciliate Tetrahymena. BMC Evol Biol 2014; 14:112. [PMID: 24885485 PMCID: PMC4045964 DOI: 10.1186/1471-2148-14-112] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 05/14/2014] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND By segregating somatic and germinal functions into large, compound macronuclei and small diploid micronuclei, respectively, ciliates can explore sexuality in ways other eukaryotes cannot. Sex, for instance, is not for reproduction but for nuclear replacement in the two cells temporarily joined in conjugation. With equal contributions from both conjugants, there is no cost of sex which theory predicts should favor asexuality. Yet ciliate asexuality is rare. The exceptional Tetrahymena has abandoned sex through loss of the micronucleus; its amicronucleates are abundant in nature where they reproduce by binary fission but never form conjugating pairs. A possible reason for their abundance is that the Tetrahymena macronucleus does not accumulate mutations as proposed by Muller's ratchet. As such, Tetrahymena amicronucleates have the potential to be very old. This study used cytochrome oxidase-1 barcodes to determine the phylogenetic origin and relative age of amicronucleates isolated from nature. RESULTS Amicronucleates constituted 25% of Tetrahymena-like wild isolates. Of the 244 amicronucleates examined for cox1 barcodes, 237 belonged to Tetrahymena, seven to other genera. Sixty percent originated from 12 named species or barcoded strains, including the model Tetrahymena thermophila, while the remaining 40% represent 19 putative new species, eight of which have micronucleate counterparts and 11 of which are known only as amicronucleates. In some instances, cox1 haplotypes were shared among micronucleate and amicronucleates collected from the same source. Phylogenetic analysis showed that most amicronucleates belong to the "borealis" clade in which mating type is determined by gene rearrangement. Some amicronucleate species were clustered on the SSU phylogenetic tree and had longer branch lengths, indicating more ancient origin. CONCLUSIONS Naturally occurring Tetrahymena amicronucleates have multiple origins, arising from numerous species. Likely many more new species remain to be discovered. Shared haplotypes indicate that some are of contemporary origin, while phylogeny indicates that others may be millions of years old. The apparent success of amicronucleate Tetrahymena may be because macronuclear assortment and recombination allow them to avoid Muller's ratchet, incorporate beneficial mutations, and evolve independently of sex. The inability of amicronucleates to mate may be the result of error(s) in mating type gene rearrangement.
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Affiliation(s)
- F Paul Doerder
- Department of Biological, Geological and Environmental Sciences, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA.
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Abstract
Tetrahymena typically is found in freshwater lakes, ponds, and streams in association with submerged or emergent vegetation. The genus consists of numerous breeding species with micronuclei and many asexual species without micronuclei. In summer months when most populations are at their peak, 30-50% of water samples may yield one or more species of Tetrahymena. This chapter describes both bulk and trapping procedures for collecting Tetrahymena and also evaluates barcode methods for species identification. The history and inbreeding of the laboratory model Tetrahymena thermophila is also discussed. There are numerous unresolved questions about Tetrahymena evolution and biogeography that may be solved by additional collecting.
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Affiliation(s)
- F Paul Doerder
- Department of Biological, Geological, and Environmental Sciences, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH, USA
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Abstract
The genus Tetrahymena is defined on the basis of a four-part oral structure composed of an undulating membrane and three membranelles. It is a monophyletic genus with 41 named species and numerous unnamed species, many of which are morphologically indistinguishable. Nuclear small subunit rRNA and mitochondrial cytochrome c oxidase subunit 1 sequences indicate two major clades, a "borealis" clade of less closely related species and an "australis" clade of more closely related species that correlate to differences in mating-type determination and frequency of amicronucleates. Members of both clades show convergence for histophagy (primarily facultative), macrostome transformation, and (rare) cyst formation. Life cycle parameters of species are presented and problematic species discussed.
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Affiliation(s)
- Denis H Lynn
- Department of Zoology, University of British Columbia, 6270 University Blvd., Vancouver, BC, Canada V6T 1Z4
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Chantangsi C, Lynn DH, Brandl MT, Cole JC, Hetrick N, Ikonomi P. Barcoding ciliates: a comprehensive study of 75 isolates of the genus Tetrahymena. Int J Syst Evol Microbiol 2007; 57:2412-2423. [PMID: 17911319 DOI: 10.1099/ijs.0.64865-0] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mitochondrial cytochrome-coxidase subunit 1 (cox1) gene has been proposed as a DNA barcode to identify animal species. To test the applicability of thecox1gene in identifying ciliates, 75 isolates of the genusTetrahymenaand three non-Tetrahymenaciliates that are close relatives ofTetrahymena,Colpidium campylum,Colpidium colpodaandGlaucoma chattoni, were selected. All tetrahymenines of unproblematic species could be identified to the species level using 689 bp of thecox1sequence, with about 11 % interspecific sequence divergence. Intraspecific isolates ofTetrahymena borealis,Tetrahymena lwoffi,Tetrahymena patulaandTetrahymena thermophilacould be identified by theircox1sequences, showing <0.65 % intraspecific sequence divergence. In addition, isolates of these species were clustered together on acox1neighbour-joining (NJ) tree. However, strains identified asTetrahymena pyriformisandTetrahymena tropicalisshowed high intraspecific sequence divergence values of 5.01 and 9.07 %, respectively, and did not cluster together on acox1NJ tree. This may indicate the presence of cryptic species. The mean interspecific sequence divergence ofTetrahymenawas about 11 times greater than the mean intraspecific sequence divergence, and this increased to 58 times when all isolates of species with high intraspecific sequence divergence were excluded. This result is similar to DNA barcoding studies on animals, indicating that congeneric sequence divergences are an order of magnitude greater than conspecific sequence divergences. Our analysis also demonstrated low sequence divergences of <1.0 % between some isolates ofT. pyriformisandTetrahymena setosaon the one hand and some isolates ofTetrahymena furgasoniandT. lwoffion the other, suggesting that the latter species in each pair is a junior synonym of the former. Overall, our study demonstrates the feasibility of using the mitochondrialcox1gene as a taxonomic marker for ‘barcoding’ and identifyingTetrahymenaspecies and some other ciliated protists.
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Affiliation(s)
- Chitchai Chantangsi
- Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Denis H Lynn
- Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Maria T Brandl
- United States Department of Agriculture, Agriculture Research Service, Western Regional Research Center, Food Safety and Health Unit, 800 Buchanan St, Albany, CA 94710, USA
| | - Jeffrey C Cole
- Protistology Department, American Type Culture Collection, 10801 University Blvd, Manassas, VA 20110-2209, USA
| | - Neil Hetrick
- Protistology Department, American Type Culture Collection, 10801 University Blvd, Manassas, VA 20110-2209, USA
| | - Pranvera Ikonomi
- Molecular Authentication Resource Center, American Type Culture Collection, 10801 University Blvd, Manassas, VA 20110-2209, USA
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BEAM CARLA, HIMES MARION. Electrophoretic Characterization of Members of theCrypthecodinium cohnii(Dinophyceae) Species Complex1. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1550-7408.1987.tb03161.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ryals PE, Smith-Somerville HE, Buhse HE. Phenotype switching in polymorphic Tetrahymena: a single-cell Jekyll and Hyde. INTERNATIONAL REVIEW OF CYTOLOGY 2002; 212:209-38. [PMID: 11804037 DOI: 10.1016/s0074-7696(01)12006-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
For nearly half a century, phenotype switching in the group of polymorphic species of the ciliate genus Tetrahymena has been the subject of investigations of the underlying mechanisms, the accompanying biochemical and structural changes, and the evolution of polymorphic survival strategy. Beginning with the pioneering systematic studies by Furgason in 1940 of hymenostome ciliates, the experimental approach rapidly expanded to include investigations of growth, nutrition, physiology, morphology, and morphogenesis in the polymorphic species. Recently, with progress in elucidation of the novel signaling ligand and identification of elements of the subsequent signal transduction cascade, in addition to the growing catalog of intracellular events associated with differentiation in these unicellular eukaryotes, we have begun to address the mechanistic basis of polymorphism. This review summarizes and integrates the history and recent discoveries concerning Tetrahymena polymorphic cells. We are now poised to answer fundamental questions about this interesting pathway of cell differentiation.
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Affiliation(s)
- Phillip E Ryals
- Department of Biochemistry and Molecular Biology, Mississippi State University, Mississippi State 39762, USA
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Strahl ED, Gillaspy GE, Falkinham JO. Fluorescent acid-fast microscopy for measuring phagocytosis of Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum by Tetrahymena pyriformis and their intracellular growth. Appl Environ Microbiol 2001; 67:4432-9. [PMID: 11571139 PMCID: PMC93186 DOI: 10.1128/aem.67.10.4432-4439.2001] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fluorescent acid-fast microscopy (FAM) was used to enumerate intracellular Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum in the ciliated phagocytic protozoan Tetrahymena pyriformis. There was a linear relationship between FAM and colony counts of M. avium cells both from cultures and within protozoa. The Ziehl-Neelsen acid-fast stain could not be used to enumerate intracellular mycobacteria because uninfected protozoa contained acid-fast, bacterium-like particles. Starved, 7-day-old cultures of T. pyriformis transferred into fresh medium readily phagocytized M. avium, M. intracellulare, and M. scrofulaceum. Phagocytosis was rapid and reached a maximum in 30 min. M. avium, M. intracellulare, and M. scrofulaceum grew within T. pyriformis, increasing by factors of 4- to 40-fold after 5 days at 30 degrees C. Intracellular M. avium numbers remained constant over a 25-day period of growth (by transfer) of T. pyriformis. Intracellular M. avium cells also survived protozoan encystment and germination. The growth and viability of T. pyriformis were not affected by mycobacterial infection. The results suggest that free-living phagocytic protozoa may be natural hosts and reservoirs for M. avium, M. intracellulare, and M. scrofulaceum.
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Affiliation(s)
- E D Strahl
- Department of Biology, Fralin Biotechnology Center, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0346, USA
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Abstract
An account is given of the early efforts to domesticate tetrahymenas as laboratory instruments for genetics. The rationale for developing a new organismic technology was the comparative leverage provided by a eukaryotic microorganism at a large evolutionary distance from both prokaryotic microbes and multicellular organisms. The tetrahymenine ciliates were considered more favorable materials than paramecia because of their ability to grow on simple media, though in fact their simpler nutritional needs have never been fully exploited. The first task was to sort the large set of phenotypically similar but evolutionarily and molecularly diverse ciliates referred to at the time as T. pyriformis. Then a species amenable to genetic manipulation was identified and its culture and cytogenetics were brought under control. Fortunately, the very first breeding system investigated--that in the species now called T. thermophila--has proved to be suitable for a wide range of studies. A large factor in the program's success was its use of the foundation previously established by studies on paramecia. However, serious unforeseen difficulties were encountered on the way to "domestication." These included inbreeding deterioration associated with their outbreeding life-style and germinal deterioration (mutational erosion) in the unexpressed micronuclear genome after long maintenance in vegetative culture. Cryogenic preservation was an important means of escaping these organismic limitations, and somatic (macronuclear) assortment has proved a valuable supplement to meiotic recombination.
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Affiliation(s)
- D L Nanney
- Department of Ecology, Ethology and Evolution, University of Illinois, Urbana 61801, USA
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Nanney DL, Park C, Preparata R, Simon EM. Comparison of sequence differences in a variable 23S rRNA domain among sets of cryptic species of ciliated protozoa. J Eukaryot Microbiol 1998; 45:91-100. [PMID: 9495037 DOI: 10.1111/j.1550-7408.1998.tb05075.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Studies were undertaken to discover the relative molecular distances separating some familiar forms of ciliated protozoa, and the genetic species they include. Sequences of 190 bases of the D2 domain of the large ribosomal nucleic acid molecule were obtained by polymerase chain reaction from protists of three distinctive groups of ciliated protozoa-Colpoda, Paramecium and Tetrahymena. Evolutionary trees were constructed for each set of sequences using the PHYLOGEN 1.0 string programs. All three groups of ciliates manifested large molecular diversity among strains difficult or impossible to distinguish morphologically. The largest single evolutionary distance within a group was the 75 differences separating Tetrahymena paravorax from the other tetrahymenids. The largest mean distance for a group was the 21.2 for the colpodids. In all the protist groups the large molecular diversity is obscured by morphological conservatism associated with constraints of ancient designs. The molecular diversity within morphotypes argues for long evolutionary coexistence of species differentiated from each other in significant physiological, ecological, or nutritional ways.
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Affiliation(s)
- D L Nanney
- Department of Ecology, Ethology and Evolution, University of Illinois, Urbana 61801, USA
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Jerome CA, Lynn DH, Simon EM. Description of Tetrahymena empidokyrea n.sp., a new species in the Tetrahymena pyriformis sibling species complex (Ciliophora, Oligohymenophorea), and an assessment of its phylogenetic position using small-subunit rRNA sequences. CAN J ZOOL 1996. [DOI: 10.1139/z96-214] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ciliates infected 0.25% of adult Aedes sp. mosquitoes collected in Guelph, Ontario. Morphological observations of live and stained specimens indicated that these ciliates belonged to the Tetrahymena pyriformis sibling species complex. This study provides the first well-documented case of insects being infected by a species in the T. pyriformis complex. Mating experiments demonstrated that these "mosquito" ciliates were reproductively isolated from previously described biological species in the complex, and are designated a new species, Tetrahymena empidokyrea n.sp. Phylogenetic analysis using SSrDNA sequences suggested that T. empidokyrea n.sp. is either basal to all species in the genus Tetrahymena or basal to one of the two main lineages in that genus.
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Allen SL, Orias E. Introduction: a tribute to David L Nanney, an experimental ciliatologist. DEVELOPMENTAL GENETICS 1992; 13:1-8. [PMID: 1395136 DOI: 10.1002/dvg.1020130102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- S L Allen
- Department of Biology, University of Michigan, Ann Arbor
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18
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Simon EM, Meyer EB. Suicide is not the inevitable outcome of "perpetual" selfing in tetrahymenines collected from natural habitats. DEVELOPMENTAL GENETICS 1992; 13:47-52. [PMID: 1395141 DOI: 10.1002/dvg.1020130108] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A significant fraction of the Tetrahymena clones isolated from natural habitats self (mating occurs within a clone). Early attempts to study such clones failed because stable subclones were rarely, if ever, observed, and isolated pairs all died. Isozyme analysis revealed that these wild selfers were a diverse group; some were very similar to T. australis, a species with synclonal mating type determination and to T. elliotti, shown recently to have a karyonidal mating type system. One originally stable clone of T. australis included some selfing clones after a few years in our laboratory. Other clones manifested unique zymograms. Subclones isolated from 18 selfer strains were heterogeneous. All subclones of several selfers mated massively at each transfer through 100 fissions. Selfing among subclones of other selfers was highly variable or not observed. Although 77% of the pairs isolated died, and 9% of the pair cultures selfed, 15 selfers yielded some viable nonselfing "immature" progeny. Additional immature progeny were obtained by isolating pairs from macronuclear retention synclones. Although some "immature" progeny eventually selfed, most remained stable. Giemsa staining revealed macronuclear anlagen in nearly all mating pairs and some anomalies. Crosses among the F1 progeny clones of the T. elliotti selfers yield viability data comparable to those from crosses among normal strains. Perhaps perpetual selfing is a mechanism of getting rid of deleterious combinations of genes and uncovering better combinations in homozygous state by playing genetic roulette.
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Affiliation(s)
- E M Simon
- Department of Ecology, Ethology, and Evolution, University of Illinois, Urbana 61801
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Preparata RM, Meyer EB, Preparata FP, Simon EM, Vossbrinck CR, Nanney DL. Ciliate evolution: the ribosomal phylogenies of the tetrahymenine ciliates. J Mol Evol 1989; 28:427-41. [PMID: 2501504 DOI: 10.1007/bf02603078] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We have assembled and analyzed nucleotide sequences for several different rRNA components from tetrahymenine ciliates. These include previously published and some new 5S and 5.8S rRNAs for a total of 18 species. We also report sequences for some 30 species obtained by primer extension analysis of a region near the 5' end of the 23S rRNAs (region 580). Phylogenetic trees have been constructed for these species, utilizing heuristics (shifting ditypic site analysis) described in a companion paper. The trees based on these sequences are consistent with each other and with those based on longer sequences of the 17S rRNA. They show the tetrahymenines to consist of a number of distinctive clusters of species. The clusters (ribosets) are homogeneous with respect to certain life history characteristics, especially the mode of mating type determination, but are inhomogeneous with respect to some morphological and life history features, such as cyst formation and adaptations to parasitism or carnivory. Using the same molecular data, we also begin to explore the relationships of the tetrahymenines to some other ciliate taxa and to some other protists.
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Affiliation(s)
- R M Preparata
- Department of Ecology, Ethology, and Evolution, University of Illinois, Urbana 61801
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Conover RK, Brunk CF. Characterization of the macronuclear DNA of different species of Tetrahymena. J Mol Evol 1986; 24:143-51. [PMID: 3031319 DOI: 10.1007/bf02099962] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The macronuclear DNAs from 20 different species of Tetrahymena were characterized using Alternating Orthogonal Field (AOF) gel electrophoresis. Each species has approximately 300 different macronuclear DNA molecules that range in size from about 100-2000 kb pairs. Although the individual macronuclear DNA molecules are not well resolved on an AOF gel, most species have a unique profile of macronuclear DNA. The sequences that hybridize with histone H4 (Tetrahymena) and ubiquitin (yeast) genes were identified on the separated macronuclear DNA molecules of the different species. All species have 2 histone H4 genes located on macronuclear DNA molecules of different sizes. This is consistent with the duplication of the histone H4 gene prior to the speciation events leading to the various species of Tetrahymena. The number and sizes of the macronuclear DNA molecules that hybridize with the ubiquitin probe vary from species to species. A grouping of the different species of Tetrahymena based on this hybridization pattern parallels groupings of the species based on ribosomal RNA sequences and isoenzymes. Some intraspecific variation among different strains of Tetrahymena thermophila was detected using ubiquitin and 5S ribosomal RNA as probes.
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Nielsen H, Simon EM, Engberg J. Updating rDNA restriction enzyme maps of Tetrahymena reveals four new intron-containing species. THE JOURNAL OF PROTOZOOLOGY 1985; 32:480-5. [PMID: 2995652 DOI: 10.1111/j.1550-7408.1985.tb04046.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The extrachromosomal rDNA molecules from a number of Tetrahymena strains were characterized by restriction enzyme mapping using three different restriction enzymes combined with gel blotting and hybridization analysis. Strains from four out of six recently described species were found to contain an intron in the 26s rRNA coding region. The evolutionary relationship among the species of the T. pyriformis complex was examined on the basis of the rDNA maps with emphasis on similarities between two of the new species and the widely studied T. thermophila and T. pigmentosa. Examination of a large number of T. pigmentosa strains showed this species to exhibit an unusual polymorphism with respect to its rDNA. It is suggested that recombinational cross-over events play a role in the formation of new rDNA alleles in this species.
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