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Bessette E, Williams B. Protists in the Insect Rearing Industry: Benign Passengers or Potential Risk? INSECTS 2022; 13:482. [PMID: 35621816 PMCID: PMC9144225 DOI: 10.3390/insects13050482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 05/10/2022] [Accepted: 05/13/2022] [Indexed: 02/01/2023]
Abstract
As the insects for food and feed industry grows, a new understanding of the industrially reared insect microbiome is needed to better comprehend the role that it plays in both maintaining insect health and generating disease. While many microbiome projects focus on bacteria, fungi or viruses, protists (including microsporidia) can also make up an important part of these assemblages. Past experiences with intensive invertebrate rearing indicate that these parasites, whilst often benign, can rapidly sweep through populations, causing extensive damage. Here, we review the diversity of microsporidia and protist species that are found in reared insect hosts and describe the current understanding of their host spectra, life cycles and the nature of their interactions with hosts. Major entomopathogenic parasite groups with the potential to infect insects currently being reared for food and feed include the Amoebozoa, Apicomplexa, Ciliates, Chlorophyta, Euglenozoa, Ichtyosporea and Microsporidia. However, key gaps exist in the understanding of how many of these entomopathogens affect host biology. In addition, for many of them, there are very limited or even no molecular data, preventing the implementation of molecular detection methods. There is now a pressing need to develop and use novel molecular tools, coupled with standard molecular diagnostic methods, to help unlock their biology and predict the effects of these poorly studied protist parasites in intensive insect rearing systems.
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Affiliation(s)
- Edouard Bessette
- Living Systems Institute, Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK;
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Copenhagen, Denmark
| | - Bryony Williams
- Living Systems Institute, Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK;
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Marumo A, Yamagishi M, Yajima J. Three-dimensional tracking of the ciliate Tetrahymena reveals the mechanism of ciliary stroke-driven helical swimming. Commun Biol 2021; 4:1209. [PMID: 34675362 PMCID: PMC8531007 DOI: 10.1038/s42003-021-02756-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/06/2021] [Indexed: 11/09/2022] Open
Abstract
Helical swimming in free-space is a common behavior among microorganisms, such as ciliates that are covered with thousands hair-like motile cilia, and is thought to be essential for cells to orient directly to an external stimulus. However, a direct quantification of their three-dimensional (3D) helical trajectories has not been reported, in part due to difficulty in tracking 3D swimming behavior of ciliates, especially Tetrahymena with a small, transparent cell body. Here, we conducted 3D tracking of fluorescent microbeads within a cell to directly visualize the helical swimming exhibited by Tetrahymena. Our technique showed that Tetrahymena swims along a right-handed helical path with right-handed rolling of its cell body. Using the Tetrahymena cell permeabilized with detergent treatment, we also observed that influx of Ca2+ into cilia changed the 3D-trajectory patterns of Tetrahymena swimming, indicating that the beating pattern of cilia is the determining factor in its swimming behavior.
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Affiliation(s)
- Akisato Marumo
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Masahiko Yamagishi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Junichiro Yajima
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan. .,Komaba Institute for Science, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo, 153-8902, Japan. .,Research Center for Complex Systems Biology, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
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Multi-gene phylogeny of Tetrahymena refreshed with three new histophagous species invading freshwater planarians. Parasitol Res 2020; 119:1523-1545. [PMID: 32152714 DOI: 10.1007/s00436-020-06628-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 02/14/2020] [Indexed: 10/24/2022]
Abstract
Planarians represent an insufficiently explored group of aquatic invertebrates that might serve as hosts of histophagous ciliates belonging to the hymenostome genus Tetrahymena. During our extensive research on freshwater planarians, parasitic tetrahymenas were detected in two of the eight planarian species investigated, namely, in Dugesia gonocephala and Girardia tigrina. Using the 16S and 18S rRNA genes as well as the barcoding cytochrome oxidase subunit I, one ciliate species was identified as T. scolopax and three species were recognized as new forms: T. acanthophora, T. dugesiae, and T. nigricans. Thus, 25% of the examined planarian taxa are positive for Tetrahymena species and three of them represent new taxa, indicating a large undescribed ciliate diversity in freshwater planarians. According to phylogenetic analyses, histophagous tetrahymenas show a low phylogenetic host specificity. Although T. acanthophora, T. dugesiae, and T. scolopax clustered together within the "borealis" clade, the former species has been detected exclusively in G. tigrina, while the two latter species only in D. gonocephala. Tetrahymena nigricans, which has been isolated only from G. tigrina, was classified within the "paravorax" clade along with T. glochidiophila which feeds on glochidia. The present phylogenetic reconstruction of ancestral life strategies suggested that the last common ancestor of the family Tetrahymenidae was free-living, unlike the progenitor of the subclass Hymenostomatia which was very likely parasitic. Consequently, there were at least seven independent shifts back to parasitism/histophagy within Tetrahymena: one each in the "paravorax" and "australis" clades and at least five transfers back to parasitism in the "borealis" clade.
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Abundant and diverse Tetrahymena species living in the bladder traps of aquatic carnivorous Utricularia plants. Sci Rep 2019; 9:13669. [PMID: 31541152 PMCID: PMC6754427 DOI: 10.1038/s41598-019-50123-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 09/06/2019] [Indexed: 01/01/2023] Open
Abstract
Ciliates are unicellular eukaryotes known for their cellular complexity and wide range of natural habitats. How they adapt to their niches and what roles they play in ecology remain largely unknown. The genus Tetrahymena is among the best-studied groups of ciliates and one particular species, Tetrahymena thermophila, is a well-known laboratory model organism in cell and molecular biology, making it an excellent candidate for study in protist ecology. Here, based on cytochrome c oxidase subunit I (COX1) gene barcoding, we identify a total of 19 different putative Tetrahymena species and two closely related Glaucoma lineages isolated from distinct natural habitats, of which 13 are new species. These latter include 11 Tetrahymena species found in the bladder traps of Utricularia plants, the most species-rich and widely distributed aquatic carnivorous plant, thus revealing a previously unknown but significant symbiosis of Tetrahymena species living among the microbial community of Utricularia bladder traps. Additional species were collected using an artificial trap method we have developed. We show that diverse Tetrahymena species may live even within the same habitat and that their populations are highly dynamic, suggesting that the diversity and biomass of species worldwide is far greater than currently appreciated.
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Kim SY, Xu D, Jung JH, Choi JK. Phylogeny and Genetic/Morphological Variation of Strombidinopsis minima-like Species (Ciliophora: Choreotrichia). J Eukaryot Microbiol 2019; 67:115-124. [PMID: 31523898 DOI: 10.1111/jeu.12761] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 08/19/2019] [Accepted: 08/30/2019] [Indexed: 11/29/2022]
Abstract
Six isolates of mineral-enveloped Strombidinopsis minima-like species were collected from the coastal waters across several regions in Korea. Morphological observations and molecular analyses were performed. The ribosomal DNA sequences (including small subunit ribosomal DNA, internal transcriber spacer 1-5.8S ribosomal DNA-internal transcriber spacer 2; and part of large subunit ribosomal DNA) of these six isolates were compared. Their morphological characteristics were also compared with those of S. minima populations reported. The marked genetic differences (with a similarity range of 96.85-98.48%) in SSU rDNA among these S. minima-like entities suggest the existence of multiple species. This finding is also supported by morphological variations detected in this study and reported in the literature (e.g. 15-32 collar membranelles in different populations). In addition, S. minima-like species are clustered with S. batos and S. sinicum, and therefore, our SSU rDNA results support previous results suggesting that the genus Strombidinopsis is not monophyletic in origin. Further collection of morphological and molecular data may facilitate the determination of a new genus carrying mineral-enveloped Strombidinopsis species.
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Affiliation(s)
- Sun Young Kim
- National Marine Biodiversity Institute of Korea, Seocheon-gun, 33662, Korea
| | - Dapeng Xu
- State Key Laboratory of Marine Environmental Science, Institute of Marine Microbes and Ecospheres, College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361102, China
| | - Jae-Ho Jung
- Department of Biology, Gangneung-Wonju National University, Gangneung, 25457, Korea
| | - Joong Ki Choi
- Department of Oceanography, Inha University, Incheon, 22212, Korea
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Fenchel T, Finlay BJ, Esteban GF. Cosmopolitan Metapopulations? Protist 2019; 170:314-318. [PMID: 31181472 DOI: 10.1016/j.protis.2019.05.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 04/26/2019] [Accepted: 05/03/2019] [Indexed: 11/15/2022]
Abstract
A "metapopulation" is a group of populations of the same species separated by space but linked by dispersal and migration. Metapopulations of macroscopic organisms tend to have geographically-restricted distributions, but this does not seem to be the case in microbial eukaryotes due to their astronomical abundance. The term "metapopulation" was first applied to protists' biogeography in the article Finlay and Fenchel (2004), published in PROTIST, which contributed to the popularity of the paper. The article considered protist species as consisting of a single, cosmopolitan population. Here, we recall this paper, and assess developments during the last 15 years with respect to the question of protist species distribution on the surface of the earth.
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Affiliation(s)
- Tom Fenchel
- Marine Biological Laboratory, University of Copenhagen, Strandpromenaden 5, DK-3000 Helsingør, Denmark
| | - Bland J Finlay
- Queen Mary University of London, School of Biological and Chemical Sciences,Mile End Road London E1 4NS, UK
| | - Genoveva F Esteban
- Bournemouth University, Department of Life and Environmental Sciences, Talbot Campus, Poole, BH12 5BB Dorset, UK.
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Xiong J, Yang W, Chen K, Jiang C, Ma Y, Chai X, Yan G, Wang G, Yuan D, Liu Y, Bidwell SL, Zafar N, Hadjithomas M, Krishnakumar V, Coyne RS, Orias E, Miao W. Hidden genomic evolution in a morphospecies-The landscape of rapidly evolving genes in Tetrahymena. PLoS Biol 2019; 17:e3000294. [PMID: 31158217 PMCID: PMC6564038 DOI: 10.1371/journal.pbio.3000294] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 06/13/2019] [Accepted: 05/13/2019] [Indexed: 01/08/2023] Open
Abstract
A morphospecies is defined as a taxonomic species based wholly on morphology, but often morphospecies consist of clusters of cryptic species that can be identified genetically or molecularly. The nature of the evolutionary novelty that accompanies speciation in a morphospecies is an intriguing question. Morphospecies are particularly common among ciliates, a group of unicellular eukaryotes that separates 2 kinds of nuclei—the silenced germline nucleus (micronucleus [MIC]) and the actively expressed somatic nucleus (macronucleus [MAC])—within a common cytoplasm. Because of their very similar morphologies, members of the Tetrahymena genus are considered a morphospecies. We explored the hidden genomic evolution within this genus by performing a comprehensive comparative analysis of the somatic genomes of 10 species and the germline genomes of 2 species of Tetrahymena. These species show high genetic divergence; phylogenomic analysis suggests that the genus originated about 300 million years ago (Mya). Seven universal protein domains are preferentially included among the species-specific (i.e., the youngest) Tetrahymena genes. In particular, leucine-rich repeat (LRR) genes make the largest contribution to the high level of genome divergence of the 10 species. LRR genes can be sorted into 3 different age groups. Parallel evolutionary trajectories have independently occurred among LRR genes in the different Tetrahymena species. Thousands of young LRR genes contain tandem arrays of exactly 90-bp exons. The introns separating these exons show a unique, extreme phase 2 bias, suggesting a clonal origin and successive expansions of 90-bp–exon LRR genes. Identifying LRR gene age groups allowed us to document a Tetrahymena intron length cycle. The youngest 90-bp exon LRR genes in T. thermophila are concentrated in pericentromeric and subtelomeric regions of the 5 micronuclear chromosomes, suggesting that these regions act as genome innovation centers. Copies of a Tetrahymena Long interspersed element (LINE)-like retrotransposon are very frequently found physically adjacent to 90-bp exon/intron repeat units of the youngest LRR genes. We propose that Tetrahymena species have used a massive exon-shuffling mechanism, involving unequal crossing over possibly in concert with retrotransposition, to create the unique 90-bp exon array LRR genes. Genomic comparison of ten morphologically very similar species of ciliate from the genus Tetrahymena reveals how parallel microevolutionary processes have shaped their genomes and created unique genes through retrotransposition.
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Affiliation(s)
- Jie Xiong
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Wentao Yang
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Kai Chen
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Chuanqi Jiang
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yang Ma
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiaocui Chai
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Guanxiong Yan
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Guangying Wang
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Dongxia Yuan
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Yifan Liu
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Shelby L. Bidwell
- J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - Nikhat Zafar
- J. Craig Venter Institute, Rockville, Maryland, United States of America
| | | | - Vivek Krishnakumar
- J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - Robert S. Coyne
- J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - Eduardo Orias
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, United States of America
| | - Wei Miao
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Animal Evolution and Genetics, Kunming, China
- State Key Laboratory of Freshwater Ecology and Biotechnology of China, Wuhan, China
- * E-mail:
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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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Affiliation(s)
- F. Paul Doerder
- Department of Biological, Geological and Environmental Sciences; Cleveland State University; Cleveland Ohio 44115 USA
| | - Joseph Frankel
- Department of Biology; University of Iowa; Iowa City Iowa 52242 USA
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11
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Zhao F, Xu K. Biodiversity patterns of soil ciliates along salinity gradients. Eur J Protistol 2016; 53:1-10. [DOI: 10.1016/j.ejop.2015.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 12/11/2015] [Accepted: 12/19/2015] [Indexed: 10/22/2022]
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Fučíková K, Lahr DJG. Uncovering Cryptic Diversity in Two Amoebozoan Species Using Complete Mitochondrial Genome Sequences. J Eukaryot Microbiol 2015. [PMID: 26211788 DOI: 10.1111/jeu.12253] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The Amoebozoa are a major eukaryotic lineage that encompasses a wide range of amoeboid organisms. The group is understudied from a systematic perspective: molecular tools have only been applied in the last 15 yr. Hence, there is an undersampling of both genes and taxa in the group especially compared to plants, animals, and fungi. Here, we present the complete mitochondrial genomes of two ubiquitous and abundant morpho-species (Acanthamoeba castellanii and Vermamoeba vermiformis). Both have mitochondrial genomes of close relatives previously available, enabling insights into recent divergences at a genomic scale, while simultaneously offering comparisons with divergence estimates obtained from traditionally used single genes, SSU rDNA and cox1. The newly sequenced mt genomes are significantly divergent from their previously sequenced conspecifics (A. castellannii 16.4% divergence at nucleotide level and 10.4% amino acid; V. vermiformis 21.6% and 13.1%, respectively), while divergence at the small subunit ribosomal DNA is below 1% within both species. Morphological analyses determined that these lineages are indistinguishable from their previously sequenced counterparts. Phylogenetic reconstructions using 26 mt genes also indicate a level of divergence that is comparable to divergence among species, while reconstructions using the small subunit ribosomal DNA (SSU rDNA) do not. In addition, we demonstrate that between closely related taxa, there are high levels of synteny, which can be explored for primer design to obtain larger fragments than the traditional barcoding genes. We conclude that, although most systematic work has relied on SSU, this gene alone can severely underestimate diversity. Thus, we suggest that the mt genome emerges as an alternative for unraveling the lower level phylogenetic relationships of Amoebozoa.
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Affiliation(s)
- Karolina Fučíková
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
| | - Daniel J G Lahr
- Department of Zoology, Institute of Biosciences, University of São Paulo, São Paulo, 05508-090, Brazil
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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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15
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The symbiotic intestinal ciliates and the evolution of their hosts. Eur J Protistol 2014; 50:166-73. [DOI: 10.1016/j.ejop.2014.01.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 01/22/2014] [Accepted: 01/24/2014] [Indexed: 11/23/2022]
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Kim SY, Choi JK, Dolan JR, Shin HC, Lee S, Yang EJ. Morphological and Ribosomal DNA-based Characterization of Six Antarctic Ciliate Morphospecies from the Amundsen Sea with Phylogenetic Analyses. J Eukaryot Microbiol 2013; 60:497-513. [DOI: 10.1111/jeu.12057] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 03/17/2013] [Accepted: 03/20/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Sun Young Kim
- Department of Oceanography; Inha University; Incheon 402-751 Korea
- Korea Polar Research Institute; KIOST; 213-3 Sondo-dong Yeonsu-gu Incheon 405-840 Korea
| | - Joong Ki Choi
- Department of Oceanography; Inha University; Incheon 402-751 Korea
| | - John R. Dolan
- UMR 7093; Laboratoire d'Océanographie de Villefranche; Marine Microbial Ecology; Université Pierre et Marie Curie and Centre National de la Recherche Scientifique (CNRS); Station Zoologique, B.P. 28 06230 Villefranche-sur-Mer France
| | - Hyoung Chul Shin
- Korea Polar Research Institute; KIOST; 213-3 Sondo-dong Yeonsu-gu Incheon 405-840 Korea
| | - SangHoon Lee
- Korea Polar Research Institute; KIOST; 213-3 Sondo-dong Yeonsu-gu Incheon 405-840 Korea
| | - Eun Jin Yang
- Korea Polar Research Institute; KIOST; 213-3 Sondo-dong Yeonsu-gu Incheon 405-840 Korea
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Stoeck T, Breiner HW, Filker S, Ostermaier V, Kammerlander B, Sonntag B. A morphogenetic survey on ciliate plankton from a mountain lake pinpoints the necessity of lineage-specific barcode markers in microbial ecology. Environ Microbiol 2013; 16:430-44. [PMID: 23848238 PMCID: PMC4208686 DOI: 10.1111/1462-2920.12194] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 06/11/2013] [Accepted: 06/11/2013] [Indexed: 02/03/2023]
Abstract
Analyses of high-throughput environmental sequencing data have become the 'gold-standard' to address fundamental questions of microbial diversity, ecology and biogeography. Findings that emerged from sequencing are, e.g. the discovery of the extensive 'rare microbial biosphere' and its potential function as a seed-bank. Even though applied since several years, results from high-throughput environmental sequencing have hardly been validated. We assessed how well pyrosequenced amplicons [the hypervariable eukaryotic V4 region of the small subunit ribosomal RNA (SSU rRNA) gene] reflected morphotype ciliate plankton. Moreover, we assessed if amplicon sequencing had the potential to detect the annual ciliate plankton stock. In both cases, we identified significant quantitative and qualitative differences. Our study makes evident that taxon abundance distributions inferred from amplicon data are highly biased and do not mirror actual morphotype abundances at all. Potential reasons included cell losses after fixation, cryptic morphotypes, resting stages, insufficient sequence data availability of morphologically described species and the unsatisfying resolution of the V4 SSU rRNA fragment for accurate taxonomic assignments. The latter two underline the necessity of barcoding initiatives for eukaryotic microbes to better and fully exploit environmental amplicon data sets, which then will also allow studying the potential of seed-bank taxa as a buffer for environmental changes.
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Affiliation(s)
- Thorsten Stoeck
- Department of Ecology, Faculty of Biology, University of Kaiserslautern, Kaiserslautern, Germany
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Quintela-Alonso P, Nitsche F, Wylezich C, Arndt H, Foissner W. A new tetrahymena (ciliophora, oligohymenophorea) from groundwater of cape town, South Africa. J Eukaryot Microbiol 2013; 60:235-46. [PMID: 23346896 DOI: 10.1111/jeu.12021] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 11/12/2012] [Accepted: 11/12/2012] [Indexed: 11/28/2022]
Abstract
The identification of species within the genus Tetrahymena is known to be difficult due to their essentially identical morphology, the occurrence of cryptic and sibling species and the phenotypic plasticity associated with the polymorphic life cycle of some species. We have combined morphology and molecular biology to describe Tetrahymena aquasubterranea n. sp. from groundwater of Cape Town, Republic of South Africa. The phylogenetic analysis compares the cox1 gene sequence of T. aquasubterranea with the cox1 gene sequences of other Tetrahymena species and uses the interior-branch test to improve the resolution of the evolutionary relationships. This showed a considerable genetic divergence of T. aquasubterranea to its next relative, T. farlyi, of 9.2% (the average cox1 divergence among bona fide species of Tetrahymena is ~ 10%). Moreover, the analysis also suggested a sister relationship between T. aquasubterranea and a big clade comprising T. farleyi, T. tropicalis, T. furgasoni and T. mobilis. The morphological data available for these species show that they share with T. aquasubterranea a pyriformis-like life style and at least two of them, T. farleyi and T. mobilis, a similar type II silverline pattern consisting of primary and secondary meridians. Tetrahymena aquasubterranea exhibits a biphasic life cycle with trophonts and theronts, is amicronucleate, and feeds on bacteria.
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Affiliation(s)
- Pablo Quintela-Alonso
- Department of General Ecology, Cologne Biocenter, Institute for Zoology, University of Cologne, Zülpicher Str. 47b, D-50674, Köln, Germany.
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Katz LA, DeBerardinis J, Hall MS, Kovner AM, Dunthorn M, Muse SV. Heterogeneous rates of molecular evolution among cryptic species of the ciliate morphospecies Chilodonella uncinata. J Mol Evol 2012; 73:266-72. [PMID: 22258433 DOI: 10.1007/s00239-011-9468-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Accepted: 10/24/2011] [Indexed: 11/27/2022]
Abstract
While molecular analyses have provided insight into the phylogeny of ciliates, the few studies assessing intraspecific variation have largely relied on just a single locus [e.g., nuclear small subunit rDNA (nSSU-rDNA) or mitochondrial cytochrome oxidase I]. In this study, we characterize the diversity of several nuclear protein-coding genes plus both nSSU-rDNA and mitochondrial small subunit rDNA (mtSSU-rDNA) of five isolates of the ciliate morphospecies Chilodonella uncinata. Although these isolates have nearly identical nSSU-rDNA sequences, they differ by up to 8.0% in mtSSU-rDNA. Comparative analyses of all loci, including β-tubulin paralogs, indicate a lack of recombination between strains, demonstrating that the morphospecies C. uncinata consists of multiple cryptic species. Further, there is considerable variation in substitution rates among loci as some protein-coding domains are nearly identical between isolates, while others differ by up to 13.2% at the amino acid level. Combining insights on macronuclear variation among isolates, the focus of this study, with published data from the micronucleus of two of these isolates, indicates that C. uncinata lineages are able to maintain both highly divergent and highly conserved genes within a rapidly evolving germline genome.
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Affiliation(s)
- Laura A Katz
- Department of Biological Sciences, Smith College, Northampton, MA 01063, 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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Strüder-Kypke MC, Lynn DH. Comparative analysis of the mitochondrial cytochromecoxidase subunit I (COI) gene in ciliates (Alveolata, Ciliophora) and evaluation of its suitability as a biodiversity marker. SYST BIODIVERS 2010. [DOI: 10.1080/14772000903507744] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Behnke A, Barger KJ, Bunge J, Stoeck T. Spatio-temporal variations in protistan communities along an O/HS gradient in the anoxic Framvaren Fjord (Norway). FEMS Microbiol Ecol 2010; 72:89-102. [PMID: 20163477 DOI: 10.1111/j.1574-6941.2010.00836.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Despite its relevance for ecology and biodiversity, the stability of spatial microeukaryote diversity patterns in time has received only little attention using gene-based strategies, and there is little knowledge about the relation of spatial vs. temporal variation. We addressed this subject by investigating seasonal fluctuations in protistan communities in three ecologically distinct marine habitats. We analyzed 3360 eukaryote small subunit rRNA gene sequences collected along an O(2)/H(2)S gradient in a Norwegian fjord in order to reveal shifts in protistan community composition and structure in three different seasons. In all nine clone libraries, ciliates and stramenopiles accounted for the largest proportion. Yet, as expected, at the phylotype level, the protistan communities from distinct habitats differed significantly, with the number of shared phylotypes between two habitats being as low as 18%. This confirmed previous notions that environmental factors along the stratification gradient shape biodiversity patterns. Surprisingly, the intrahabitat community composition and structure varied at a comparable order of magnitude over time, with only 18-28% phylotypes shared within the same habitat. Our study demonstrates that the consideration of local fluctuations in microeukaryote diversity over time offers additional information for diversity surveys and can significantly contribute to the revelation of spatial protistan community patterns.
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Affiliation(s)
- Anke Behnke
- Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany.
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Relative diversity and community structure of ciliates in stream biofilms according to molecular and microscopy methods. Appl Environ Microbiol 2009; 75:5261-72. [PMID: 19561192 DOI: 10.1128/aem.00412-09] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ciliates are an important component of aquatic ecosystems, acting as predators of bacteria and protozoa and providing nutrition for organisms at higher trophic levels. Understanding of the diversity and ecological role of ciliates in stream biofilms is limited, however. Ciliate diversity in biofilm samples from four streams subject to different impacts by human activity was assessed using microscopy and terminal restriction fragment length polymorphism (T-RFLP) analysis of 18S rRNA sequences. Analysis of 3' and 5' terminal fragments yielded very similar estimates of ciliate diversity. The diversity detected using microscopy was consistently lower than that suggested by T-RFLP analysis, indicating the existence of genetic diversity not apparent by morphological examination. Microscopy and T-RFLP analyses revealed similar relative trends in diversity between different streams, with the lowest level of biofilm-associated ciliate diversity found in samples from the least-impacted stream and the highest diversity in samples from moderately to highly impacted streams. Multivariate analysis provided evidence of significantly different ciliate communities in biofilm samples from different streams and seasons, particularly between a highly degraded urban stream and less impacted streams. Microscopy and T-RFLP data both suggested the existence of widely distributed, resilient biofilm-associated ciliates as well as ciliate taxa restricted to sites with particular environmental conditions, with cosmopolitan taxa being more abundant than those with restricted distributions. Differences between ciliate assemblages were associated with water quality characteristics typical of urban stream degradation and may be related to factors such as nutrient availability and macroinvertebrate communities. Microscopic and molecular techniques were considered to be useful complementary approaches for investigation of biofilm ciliate communities.
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Howe AT, Bass D, Vickerman K, Chao EE, Cavalier-Smith T. Phylogeny, Taxonomy, and Astounding Genetic Diversity of Glissomonadida ord. nov., The Dominant Gliding Zooflagellates in Soil (Protozoa: Cercozoa). Protist 2009; 160:159-89. [DOI: 10.1016/j.protis.2008.11.007] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Accepted: 11/09/2008] [Indexed: 11/30/2022]
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Banerji A, Morin PJ. Phenotypic plasticity, intraguild predation and anti-cannibal defences in an enigmatic polymorphic ciliate. Funct Ecol 2009. [DOI: 10.1111/j.1365-2435.2008.01499.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Cloning, characterization, and gene expression analysis of a novel cadmium metallothionein gene in Tetrahymena pigmentosa. Gene 2008; 423:29-35. [PMID: 18675523 DOI: 10.1016/j.gene.2008.04.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 04/25/2008] [Accepted: 04/25/2008] [Indexed: 11/20/2022]
Abstract
A novel cadmium-inducible metallothionein (MT) gene (Tpig-MT1) was cloned and sequenced from the ciliate Tetrahymena pigmentosa. The number of deduced amino acids is 118. The polypeptide possesses CCC and CC clusters characteristic of typical Tetrahymena Cd-inducible MTs. The structure of Tpig-MT1 is different from the reported Cd-MT in T. pyriformis, T. thermophila and T. pigmentosa. Tpig-MT1 contains two intragenic tandem repeats with 72.9% identity described as Tpig-MT1 (repeat A1) and Tpig-MT1 (repeat A2). The transcriptional response of Tpig-MT1 gene to different heavy metals (Cd, Cu, Zn, Hg, Pb) and oxidative stress (H(2)O(2)) was measured using real-time quantitative PCR. The results showed that the gene was quickly induced (1 h) by the five heavy metals and the order of expression level was Hg>Pb>Cd>Cu>Zn. The induction effect of H(2)O(2) was 5-fold after about 15 min, but soon decreased to a non-significant level (30 min). The genetic diversity of Tetrahymena MT genes is discussed in relation to the unique structure of the Tpig-MT1 gene and other reported Cd-MT isoforms.
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Global Diversity and Biogeography of Skeletonema Species (Bacillariophyta). Protist 2008; 159:177-93. [DOI: 10.1016/j.protis.2007.09.004] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Accepted: 09/01/2007] [Indexed: 11/22/2022]
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29
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Genetic analysis of theParamecium aureliaspecies complex (Protozoa: Ciliophora) by classical and molecular methods. SYST BIODIVERS 2007. [DOI: 10.1017/s1477200007002307] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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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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Dunthorn M, Foissner W, Katz LA. Molecular phylogenetic analysis of class Colpodea (phylum Ciliophora) using broad taxon sampling. Mol Phylogenet Evol 2007; 46:316-27. [PMID: 17920937 DOI: 10.1016/j.ympev.2007.08.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2007] [Revised: 08/01/2007] [Accepted: 08/09/2007] [Indexed: 11/26/2022]
Abstract
The ciliate class Colpodea provides a powerful case in which a molecular genealogy can be compared to a detailed morphological taxonomy of a microbial group. Previous analyses of the class using the small-subunit rDNA are based on sparse taxon sampling, and are therefore of limited use in comparisons with morphologically-based classifications. Taxon sampling is increased here to include all orders within the class, and more species within previously sampled orders and in the species rich genus Colpoda. Results indicate that the Colpodea may be paraphyletic, although there is no support for deep nodes. The orders Bursariomorphida, Grossglockneriida, and Sorogenida are monophyletic. The orders Bryometopida, Colpodida, and Cyrtolophosidida, and the genus Colpoda, are not monophyletic. Although congruent in many aspects, the conflict between some nodes on this single gene genealogy and morphology-based taxonomy suggests the need for additional markers as well as a reassessment of the Colpodea taxonomy.
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Affiliation(s)
- Micah Dunthorn
- University of Massachusetts Amherst, Amherst, MA 01003, USA.
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Fenchel T, Finlay BJ. The diversity of microbes: resurgence of the phenotype. Philos Trans R Soc Lond B Biol Sci 2007; 361:1965-73. [PMID: 17062414 PMCID: PMC1764925 DOI: 10.1098/rstb.2006.1924] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The introduction of molecular genetic methods has caused confusion about the nature of microbial species. Environmental DNA extraction has indicated the existence of a vast diversity of genotypes, but how this relates to functional and phenotypic diversity has not been sufficiently explored. It has been implied that genetic distance per se correlates with phenotypic differentiation and thus reflects subtle (but undiscovered) adaptive fine-tuning to the environment, and that microbes may show biogeographic patterns at the genetic level. Here, we argue that no theoretically based species concept exists; species represent only the basic unit in the taxonomic hierarchy. The significance of naming species is that it organizes biological information. The reason why microbial species collectively represent large genetic differences is owing to huge absolute population sizes, absence of allopatric speciation and low extinction rates. Microbial phenotypes are, therefore, ancient in terms of the geological time-scale and have been maintained through stabilizing selection. These problems are discussed with special reference to eukaryotic micro-organisms.
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Affiliation(s)
- Tom Fenchel
- Marine Biological Laboratory, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark.
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Diversity and geographic distribution of ciliates (Protista: Ciliophora). PROTIST DIVERSITY AND GEOGRAPHICAL DISTRIBUTION 2007. [DOI: 10.1007/978-90-481-2801-3_9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Finlay BJ, Esteban GF, Brown S, Fenchel T, Hoef-Emden K. Multiple Cosmopolitan Ecotypes within a Microbial Eukaryote Morphospecies. Protist 2006; 157:377-90. [PMID: 16887389 DOI: 10.1016/j.protis.2006.05.012] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2006] [Accepted: 05/28/2006] [Indexed: 11/16/2022]
Abstract
Microbial eukaryotes that are morphologically indistinguishable (i.e. 'morphospecies') tend to be genetically diverse. While most protist morphospecies have cosmopolitan distribution, it has been suggested that ribotypes (unique rRNA gene sequences) or rRNA sequence clusters do have biogeography and such clusters may correlate with particular (non-morphological) adaptations. We have studied this in the ciliated protozoan morphospecies Cyclidium glaucoma. Fifty-four isolates collected worldwide represented 31 distinct ribotypes. There was no evidence of biogeographic distribution patterns. For example, identical ribotypes occurred in samples from Argentina, Peru, Morocco, Russia and Ukraine; in samples from Denmark and Australia; and in samples from Great Salt Lake and hyperhaline ponds in Spain. The morphospecies Cyclidium glaucoma is euryhaline and occurs in freshwater, brackish water, seawater, and hyperhaline waters. Evidence suggests that one ribotype cluster occurs only in marine or brackish habitats, and another one has so far been found only in hyperhaline habitats. Two clades seem to occur only in freshwater, but one clade includes ribotypes that were found in freshwater as well as in brackish water.
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Affiliation(s)
- Bland J Finlay
- Centre for Ecology and Hydrology, Winfrith Technology Centre, Winfrith Newburgh, Dorchester, Dorset DT2 8ZD, UK.
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Lynn DH, Strüder-Kypke MC. Species of Tetrahymena Identical by Small Subunit rRNA Gene Sequences are Discriminated by Mitochondrial Cytochrome c Oxidase I Gene Sequences. J Eukaryot Microbiol 2006; 53:385-7. [PMID: 16968457 DOI: 10.1111/j.1550-7408.2006.00116.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The mitochondrial cytochrome c oxidase 1 (CO1) genes of two isolates of each of the seven mating types of Tetrahymena thermophila were sequenced and found to differ by < 1% in nucleotide sequence and to be identical by putative protein sequence. As this gene was highly conserved in this species, the CO1 gene sequence was determined for four pairs of Tetrahymena species identical in their small subunit rRNA gene sequences. The following pairs of species showed from 1% to 12% divergence at the nucleotide level, enabling discrimination of all these species: (1) Tetrahymena pyriformis strain T and Tetrahymena setosa strain HZ-1; (2) Tetrahymena canadensis strain UM1215 and Tetrahymena rostrata strain ID-3; (3) Tetrahymena pigmentosa strain UM1285 and Tetrahymena hyperangularis strain EN112; and (4) Tetrahymena tropicalis strain TC-105 and Tetrahymena mobilis. However, because of the synonymous nature of the majority of substitutions, the pairs of species were identical based on the putative protein sequence.
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Affiliation(s)
- Denis H Lynn
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
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Barth D, Krenek S, Fokin SI, Berendonk TU. Intraspecific genetic variation in Paramecium revealed by mitochondrial cytochrome C oxidase I sequences. J Eukaryot Microbiol 2006; 53:20-5. [PMID: 16441579 DOI: 10.1111/j.1550-7408.2005.00068.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Studies of intraspecific genetic diversity of ciliates, such as population genetics and biogeography, are particularly hampered by the lack of suitable DNA markers. For example, sequences of the non-coding ribosomal internal transcribed spacer (ITS) regions are often too conserved for intraspecific analyses. We have therefore identified primers for the mitochondrial cytochrome c oxidase I (COI) gene and applied them for intraspecific investigations in Paramecium caudatum and Paramecium multimicronucleatum. Furthermore, we obtained sequences of the ITS regions from the same strains and carried out comparative sequence analyses of both data sets. The mitochondrial sequences revealed substantially higher variation in both Paramecium species, with intraspecific divergences up to 7% in P. caudatum and 9.5% in P. multimicronucleatum. Moreover, an initial survey of the population structure discovered different mitochondrial haplotypes of P. caudatum in one pond, thereby demonstrating the potential of this genetic marker for population genetic analyses. Our primers successfully amplified the COI gene of other Paramecium. This is the first report of intraspecific variation in free-living protozoans based on mitochondrial sequence data. Our results show that the high variation in mitochondrial DNA makes it a suitable marker for intraspecific and population genetic studies.
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Affiliation(s)
- Dana Barth
- Molecular Evolution and Animal Systematics, Institute of Biology II, University of Leipzig, 04103 Leipzig, Germany.
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Šlapeta J, Moreira D, López-García P. The extent of protist diversity: insights from molecular ecology of freshwater eukaryotes. Proc Biol Sci 2006; 272:2073-81. [PMID: 16191619 PMCID: PMC1559898 DOI: 10.1098/rspb.2005.3195] [Citation(s) in RCA: 155] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Classical studies on protist diversity of freshwater environments worldwide have led to the idea that most species of microbial eukaryotes are known. One exemplary case would be constituted by the ciliates, which have been claimed to encompass a few thousands of ubiquitous species, most of them already described. Recently, molecular methods have revealed an unsuspected protist diversity, especially in oceanic as well as some extreme environments, suggesting the occurrence of a hidden diversity of eukaryotic lineages. In order to test if this holds also for freshwater environments, we have carried out a molecular survey of small subunit ribosomal RNA genes in water and sediment samples of two ponds, one oxic and another suboxic, from the same geographic area. Our results show that protist diversity is very high. The majority of phylotypes affiliated within a few well established eukaryotic kingdoms or phyla, including alveolates, cryptophytes, heterokonts, Cercozoa, Centroheliozoa and haptophytes, although a few sequences did not display a clear taxonomic affiliation. The diversity of sequences within groups was very large, particularly that of ciliates, and a number of them were very divergent from known species, which could define new intra-phylum groups. This suggests that, contrary to current ideas, the diversity of freshwater protists is far from being completely described.
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Hori M, Tomikawa I, Przyboś E, Fujishima M. Comparison of the evolutionary distances among syngens and sibling species of Paramecium. Mol Phylogenet Evol 2006; 38:697-704. [PMID: 16293424 DOI: 10.1016/j.ympev.2005.09.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2005] [Revised: 08/30/2005] [Accepted: 09/02/2005] [Indexed: 11/20/2022]
Abstract
The morphospecies of the genus Paramecium have several mating type groups, so-called syngens, composed of cells of complementary mating types. The Paramecium aurelia complex is composed of 15 sibling species assigned to the species from the syngen. To increase our understanding of the evolutionary relationships among syngen and sibling species of the genus Paramecium, we investigated the gene sequences of cytosol-type hsp70 from 7 syngens of Paramecium caudatum and 15 sibling species of P. aurelia. Molecular phylogenetic trees indicated that the P. aurelia complex could be divided into four lineages and separated into each sibling species. However, we did not find any obvious genetic distance among syngens of P. caudatum, and they could only be separated into two closely related groups. These results indicated that the concept of syngens in P. caudatum differs quite markedly from that of the P. aurelia complex. In addition, we also discuss the relationships among these species and other species, Paramecium jenningsi and Paramecium multimicronucleatum, which were once classified as varieties of P. aurelia.
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Affiliation(s)
- Manabu Hori
- Biological Institute, Faculty of Science, Yamaguchi University, Yamaguchi 753-8512, Japan.
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von der Heyden S, Cavalier-Smith T. Culturing and environmental DNA sequencing uncover hidden kinetoplastid biodiversity and a major marine clade within ancestrally freshwater Neobodo designis. Int J Syst Evol Microbiol 2006; 55:2605-2621. [PMID: 16280534 DOI: 10.1099/ijs.0.63606-0] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bodonid flagellates (class Kinetoplastea) are abundant, free-living protozoa in freshwater, soil and marine habitats, with undersampled global biodiversity. To investigate overall bodonid diversity, kinetoplastid-specific PCR primers were used to amplify and sequence 18S rRNA genes from DNA extracted from 16 diverse environmental samples; of 39 different kinetoplastid sequences, 35 belong to the subclass Metakinetoplastina, where most group with the genus Neobodo or the species Bodo saltans, whilst four group with the subclass Prokinetoplastina (Ichthyobodo). To study divergence between freshwater and marine members of the genus Neobodo, 26 new Neobodo designis strains were cultured and their 18S rRNA genes were sequenced. It is shown that the morphospecies N. designis is a remarkably ancient species complex with a major marine clade nested among older freshwater clades, suggesting that these lineages were constrained physiologically from moving between these environments for most of their long history. Other major bodonid clades show less-deep separation between marine and freshwater strains, but have extensive genetic diversity within all lineages and an apparently biogeographically distinct distribution of B. saltans subclades. Clade-specific 18S rRNA gene primers were used for two N. designis subclades to test their global distribution and genetic diversity. The non-overlap between environmental DNA sequences and those from cultures suggests that there are hundreds, possibly thousands, of different rRNA gene sequences of free-living bodonids globally.
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Abstract
The species Paramecium aurelia sensu latu, containing 15 sexually isolated subspecies (syngens), is the classic example of a sibling species complex in the ciliates. Using DNA sequence comparison, it is now possible to see whether this example parallels other studied sibling species complexes. We sequenced the internal transcribed spacer (ITS) region of the nuclear ribosomal cistron for 13 of the syngens plus two other Paramecium species and several Tetrahymena spp. Using available spirotrich sequences of the internal transcribed spacer 2 (ITS2), we established the RNA transcript folding pattern for ciliates. Ciliates exhibit the two highly conserved helices in their RNA transcript folding pattern in common with other eukaryotes, despite their unusual nuclear behavior and their presumed low copy number of micronuclear ribosomal repeats. Consequently, the set of 111-116 ITS2 nucleotide positions that are relatively conserved in evolution can be derived and used for comparative analysis. Mating behavior (i.e. gamete agglutination and fusion) is the character showing greatest correlation with the degree of ITS2 evolution in the P. aurelia complex, as also found in other eukaryotes. The degree of change in the ITS2 relatively conserved sequences found among the sibling species of P. aurelia is the same degree as found among the sibling species of the Drosophila melanogaster-mauritania-sechellia-simulans-yakuba species complex. The relatively conserved subregion of ITS2, determined from transcript secondary structure, is a tool for identifying the level of the biological species in the absence of knowledge of sexual compatibility in both micro- and macro-eukaryote species complexes.
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Affiliation(s)
- A W Coleman
- Division of Biology and Medicine, Brown University, Providence, Rhode Island 02912, USA.
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41
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Hide G, Hughes JM, McNuff R. A rapid and simple method of detection of Blepharisma japonicum using PCR and immobilisation on FTA paper. BMC Ecol 2003; 3:7. [PMID: 14516472 PMCID: PMC239857 DOI: 10.1186/1472-6785-3-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2003] [Accepted: 09/30/2003] [Indexed: 11/13/2022] Open
Abstract
Background The rapid expansion in the availability of genome and DNA sequence information has opened up new possibilities for the development of methods for detecting free-living protozoa in environmental samples. The protozoan Blepharisma japonicum was used to investigate a rapid and simple detection system based on polymerase chain reaction amplification (PCR) from organisms immobilised on FTA paper. Results Using primers designed from the α-tubulin genes of Blepharisma, specific and sensitive detection to the equivalent of a single Blepharisma cell could be achieved. Similar detection levels were found using water samples, containing Blepharisma, which were dried onto Whatman FTA paper. Conclusion This system has potential as a sensitive convenient detection system for Blepharisma and could be applied to other protozoan organisms.
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Affiliation(s)
- Geoff Hide
- Centre for Parasite Biology, Molecular Epidemiology and Ecology, Biosciences Research Institute, School of Environment and Life Sciences, University of Salford, Salford, UK, M5 4WT
| | - Jacqueline M Hughes
- Centre for Parasite Biology, Molecular Epidemiology and Ecology, Biosciences Research Institute, School of Environment and Life Sciences, University of Salford, Salford, UK, M5 4WT
| | - Robert McNuff
- SCIENTO, 61 Bury Old Road, Whitefield, Manchester, UK, M45 6TB
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Brunk CF, Lee LC, Tran AB, Li J. Complete sequence of the mitochondrial genome of Tetrahymena thermophila and comparative methods for identifying highly divergent genes. Nucleic Acids Res 2003; 31:1673-82. [PMID: 12626709 PMCID: PMC152872 DOI: 10.1093/nar/gkg270] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2002] [Revised: 01/16/2003] [Accepted: 01/16/2003] [Indexed: 11/13/2022] Open
Abstract
The complete sequence of the mitochondrial genome of Tetrahymena thermophila has been determined and compared with the mitochondrial genome of Tetrahymena pyriformis. The sequence similarity clearly indicates homology of the entire T.thermophila and T.pyriformis mitochondrial genomes. The T.thermophila genome is very compact, most of the intergenic regions are short (only three are longer than 63 bp) and comprise only 3.8% of the genome. The nad9 gene is tandemly duplicated in T.thermophila. Long terminal inverted repeats and the nad9 genes are undergoing concerted evolution. There are 55 putative genes: three ribosomal RNA genes, eight transfer RNA genes, 22 proteins with putatively assigned functions and 22 additional open reading frames of unknown function. In order to extend indications of homology beyond amino acid sequence similarity we have examined a number of physico-chemical properties of the mitochondrial proteins, including theoretical pI, molecular weight and particularly the predicted transmembrane spanning regions. This approach has allowed us to identify homologs to ymf58 (nad4L), ymf62 (nad6) and ymf60 (rpl6).
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Affiliation(s)
- Clifford F Brunk
- Department of Organismic Biology, Ecology and Evolution, University of California-Los Angeles, Los Angeles, CA 90095-1606, USA.
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Foissner W. Morphology and ontogenesis of Lambornella trichoglossa nov. spec., a new tetrahymenid ciliate (Protozoa, Ciliophora) from Brasilian tank bromeliads (Bromeliaceae). Eur J Protistol 2003. [DOI: 10.1078/0932-4739-00887] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Abstract
A comparative study of macronuclear DNA molecules from the following Paramecium species: the P. aurelia complex, P. caudatum, P. bursaria, P. putrinum and P. multimicronucleatum was performed using pulsed-field gel electrophoresis. The electrophoretic pattern was constant and unique for each species, and is referred to herein as its electrokaryotype. Large differences were observed between Paramecium species according to the range and major size of macronuclear DNA fragments, while different strains of the same species, even belonging to different syngens, were characterized by the same electrokaryotype. In this respect sibling species from the P. aurelia complex are as similar as syngens in other Paramecium species, but are unlike conventional species. The principles and value of electrokaryotype analysis for application to ciliates are discussed.
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Affiliation(s)
- Maria S Rautian
- Biological Institute of St. Petersburg State University, Stary Peterhof, Russia.
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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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Petroni G, Dini F, Verni F, Rosati G. A molecular approach to the tangled intrageneric relationships underlying phylogeny in Euplotes (Ciliophora, Spirotrichea). Mol Phylogenet Evol 2002; 22:118-30. [PMID: 11796035 DOI: 10.1006/mpev.2001.1030] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The cosmopolitan genus Euplotes is remarkable among ciliates for its species richness. To understand the still tangled taxonomy and phylogenetic relationships within the genus, small subunit rRNA sequences of 11 morphologically defined species colonizing different habitats were determined. Euplotes 18S rRNA is unique among ciliates for its anomalous length and high evolutionary rate. Phylogenetic reconstruction pointed to a high divergence between this genus and the other Spirotrichea, together with a high variability within the genus. Some of the relationships within the Euplotes group were also resolved. Data from the literature, based on morphological features, habitat, and symbiotic relationships, have been compared with our results and are critically discussed. In many cases, the molecular phylogenetic analysis disagreed with species relatedness established on morphological and ecological grounds. The occurrence of a radiation phenomenon in the evolution of the genus is postulated.
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MESH Headings
- Animals
- Base Sequence
- DNA, Protozoan/genetics
- DNA, Ribosomal/genetics
- Environment
- Euplotes/classification
- Euplotes/genetics
- Euplotes/ultrastructure
- Evolution, Molecular
- Genetic Variation
- Microscopy, Electron, Scanning
- Molecular Sequence Data
- Nucleic Acid Conformation
- Phylogeny
- RNA, Protozoan/chemistry
- RNA, Protozoan/genetics
- RNA, Ribosomal, 18S/chemistry
- RNA, Ribosomal, 18S/genetics
- Sequence Homology, Nucleic Acid
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Affiliation(s)
- Giulio Petroni
- Dipartimento di Etologia, Ecologia, Evoluzione, Università di Pisa, via A., Volta 4-6, 56126 Pisa, Italy
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Strüder-Kypke MC, Wright ADG, Jerome CA, Lynn DH. Parallel evolution of histophagy in ciliates of the genus Tetrahymena. BMC Evol Biol 2001; 1:5. [PMID: 11701089 PMCID: PMC59677 DOI: 10.1186/1471-2148-1-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2001] [Accepted: 10/09/2001] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Species of Tetrahymena were grouped into three complexes based on morphological and life history traits: the pyriformis complex of microstomatous forms; the patula complex of microstome-macrostome transformers; and the rostrata complex of facultative and obligate histophages. We tested whether these three complexes are paraphyletic using the complete sequence of the small subunit rDNA (SSrDNA). RESULTS In addition to the 16 species of Tetrahymena whose SSrDNA sequences are known, we sequenced the complete SSrDNA from the following histophagous Tetrahymena species; Tetrahymena bergeri, Tetrahymena mobilis, Tetrahymena rostrata, and Tetrahymena setosa as well as the macrostome species Tetrahymena vorax. We also included a ciliate tentatively identified as Lambornella sp., a parasite of the mosquito Aedes sp. We confirmed earlier results using SSrDNA, which showed two distinct clusters of Tetrahymena species: the australis group and borealis group. The genetic distances among Tetrahymena are in general very small. However, all nodes were supported by high bootstrap values. With the exception of T. bergeri and T. corlissi, which are both histophagous and group as sister species, all other histophagous Tetrahymena species are most closely related to a bacterivorous species. Furthermore, Lambornella sp. and T. empidokyrea, both mosquito parasites, are sister species, although there is a considerable genetic distance between them. CONCLUSIONS There has been parallel evolution of histophagy in the genus Tetrahymena and the three classical species complexes are paraphyletic. As the genus Lambornella arises within the Tetrahymena clade, it is not likely a defensible one.
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Affiliation(s)
- Michaela C Strüder-Kypke
- Department of Zoology, College of Biological Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - André-Denis G Wright
- Department of Zoology, College of Biological Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada
- CSIRO Livestock Industries, Private Bag 5, Wembley, WA 6913, Australia
| | - Cheryl A Jerome
- Department of Zoology, College of Biological Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada
- Department of Botany, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - Denis H Lynn
- Department of Zoology, College of Biological Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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Frankel J, Williams NE, Nelsen EM, Keeling PJ. An evaluation of Hsp90 as a mediator of cortical patterning in Tetrahymena. J Eukaryot Microbiol 2001; 48:147-60. [PMID: 12095102 DOI: 10.1111/j.1550-7408.2001.tb00297.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
This study asks two questions: 1) whether Hsp90 is involved in the regulation of cortical patterning in Tetrahymena, and 2) if it is, whether specific defects in this regulation can be attributed to functional insufficiency of the Hsp90 molecule. To address question 1, we compared the effects of a specific inhibitor of Hsp90, geldanamycin, on population growth and on development of the oral apparatus in two Tetrahymena species, T. pyriformis and T. thermophila. We observed that geldanamycin inhibits population growth in both species at very low concentrations, and that it has far more severe effects on oral patterning in T. pyriformis than in T. thermophila. These effects are parallel to those of high temperature in the same two species, and provide a tentative affirmative answer to the first question. To address question 2, we ascertained the base sequence of the genes that encode the Hsp90 molecules which are induced at high temperatures in both Tetrahymena species, as well as corresponding sequences in Paramecium tetraurelia. Extensive comparative analyses of the deduced amino acid sequences of the Hsp90 molecules of the two Tetrahymena species indicate that on the basis of what we currently know about Hsp90 both proteins are equally likely to be functional. Phylogenetic analyses of Hsp90 amino acid sequences indicate that the two Tetrahymena Hsp90 molecules have undergone a similar number of amino acid substitutions from their most recent common ancestor, with none of these corresponding to any known functionally critical region of the molecule. Thus there is no evidence that the Hsp90 molecule of T. pyriformis is functionally impaired; the flaw in the control of cortical patterning is more likely to be caused by defects in mechanism(s) that mediate the response to Hsp90, as would be expected from the "Hsp90 capacitor" model of Rutherford and Lindquist.
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Affiliation(s)
- J Frankel
- Department of Biological Sciences, University of Iowa, Iowa City 52242, USA.
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Foissner W, Schiller W. Stable for 15 million years: scanning electron microscope investigation of Miocene euglyphid thecamoebians from Germany, with description of the new genus Scutiglypha. Eur J Protistol 2001. [DOI: 10.1078/0932-4739-00012] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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50
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Strüder-Kypke MC, Wright AD, Fokin SI, Lynn DH. Phylogenetic relationships of the Subclass Peniculia (Oligohymenophorea, Ciliophora) inferred from small subunit rRNA gene sequences. J Eukaryot Microbiol 2000; 47:419-29. [PMID: 11140457 DOI: 10.1111/j.1550-7408.2000.tb00069.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Peniculine ciliates have been recognized as a distinct higher taxon of ciliates for almost 50 years. However, phylogenetic relationships within the Subclass Peniculia are still unsettled. To contribute to our understanding of their phylogeny and provide evidence for the position of Urocentrum turbo, we sequenced its small subunit (SS) rRNA gene and the SSrRNA genes from Lembadion bullinum, Frontonia sp., Paramecium caudatum, Paramecium multimicronucleatum, Paramecium putrinum, and Paramecium woodruffi. Urocentrum turbo was the only one of these species not to exhibit a shortened Helix E10_1, which we conclude characterizes the "higher" peniculines. Except for U. turbo, the peniculines are strongly supported as a monophyletic clade with Lembadion, Frontonia, and Paramecium species forming separate and strongly supported clades by bootstrap analysis using distance matrix, maximum parsimony, and maximum likelihood methods. Urocentrum turbo is associated with different lineages, depending upon the analysis used. The Paramecium species form at least four clades with the Paramecium aurelia subgroup being the most derived. We conclude that the Subclass Peniculia should be divided into two orders, the Order Urocentrida and Order Peniculida, with the latter order having two suborders, the Suborder Frontoniina and Peniculina. We place U. turbo with the peniculines because of shared morphological and stomatogenetic features.
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Affiliation(s)
- M C Strüder-Kypke
- Department of Zoology, College of Biological Science, University of Guelph, Ontario, Canada.
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