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Zhang Y, Li H, Wang Y, Nie M, Zhang K, Pan J, Zhang Y, Ye Z, Zufall RA, Lynch M, Long H. Mitogenomic architecture and evolution of the soil ciliates Colpoda. mSystems 2024; 9:e0116123. [PMID: 38259100 PMCID: PMC10878089 DOI: 10.1128/msystems.01161-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 12/14/2023] [Indexed: 01/24/2024] Open
Abstract
Colpoda are cosmopolitan unicellular eukaryotes primarily inhabiting soil and benefiting plant growth, but they remain one of the least understood taxa in genetics and genomics within the realm of ciliated protozoa. Here, we investigate the architecture of de novo assembled mitogenomes of six Colpoda species, using long-read sequencing and involving 36 newly isolated natural strains in total. The mitogenome sizes span from 43 to 63 kbp and typically contain 28-33 protein-coding genes. They possess a linear structure with variable telomeres and central repeats, with one Colpoda elliotti strain isolated from Tibet harboring the longest telomeres among all studied ciliates. Phylogenomic analyses reveal that Colpoda species started to diverge more than 326 million years ago, eventually evolving into two distinct groups. Collinearity analyses also reveal significant genomic divergences and a lack of long collinear blocks. One of the most notable features is the exceptionally high level of gene rearrangements between mitochondrial genomes of different Colpoda species, dominated by gene loss events. Population-level mitogenomic analysis on natural strains also demonstrates high sequence divergence, regardless of geographic distance, but the gene order remains highly conserved within species, offering a new species identification criterion for Colpoda species. Furthermore, we identified underlying heteroplasmic sites in the majority of strains of three Colpoda species, albeit without a discernible recombination signal to account for this heteroplasmy. This comprehensive study systematically unveils the mitogenomic structure and evolution of these ancient and ecologically significant Colpoda ciliates, thus laying the groundwork for a deeper understanding of the evolution of unicellular eukaryotes.IMPORTANCEColpoda, one of the most widespread ciliated protozoa in soil, are poorly understood in regard to their genetics and evolution. Our research revealed extreme mitochondrial gene rearrangements dominated by gene loss events, potentially leading to the streamlining of Colpoda mitogenomes. Surprisingly, while interspecific rearrangements abound, our population-level mitogenomic study revealed a conserved gene order within species, offering a potential new identification criterion. Phylogenomic analysis traced their lineage over 326 million years, revealing two distinct groups. Substantial genomic divergence might be associated with the lack of extended collinear blocks and relaxed purifying selection. This study systematically reveals Colpoda ciliate mitogenome structures and evolution, providing insights into the survival and evolution of these vital soil microorganisms.
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Affiliation(s)
- Yuanyuan Zhang
- Key Laboratory of Evolution and Marine Biodiversity (Ministry of Education), Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, Shandong Province, China
- Laboratory for Marine Biology and Biotechnology, Laoshan Laboratory, Qingdao, Shandong Province, China
| | - Haichao Li
- Key Laboratory of Evolution and Marine Biodiversity (Ministry of Education), Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, Shandong Province, China
| | - Yaohai Wang
- Key Laboratory of Evolution and Marine Biodiversity (Ministry of Education), Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, Shandong Province, China
| | - Mu Nie
- Key Laboratory of Evolution and Marine Biodiversity (Ministry of Education), Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, Shandong Province, China
| | - Kexin Zhang
- Key Laboratory of Evolution and Marine Biodiversity (Ministry of Education), Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, Shandong Province, China
| | - Jiao Pan
- Key Laboratory of Evolution and Marine Biodiversity (Ministry of Education), Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, Shandong Province, China
| | - Yu Zhang
- Key Laboratory of Evolution and Marine Biodiversity (Ministry of Education), Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, Shandong Province, China
- School of Mathematics Science, Ocean University of China, Qingdao, Shandong Province, China
| | - Zhiqiang Ye
- School of Life Sciences, Central China Normal University, Wuhan, Hubei Province, China
| | - Rebecca A. Zufall
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA
| | - Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, Arizona, USA
| | - Hongan Long
- Key Laboratory of Evolution and Marine Biodiversity (Ministry of Education), Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, Shandong Province, China
- Laboratory for Marine Biology and Biotechnology, Laoshan Laboratory, Qingdao, Shandong Province, China
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Ewers I, Rajter L, Czech L, Mahé F, Stamatakis A, Dunthorn M. Interpreting phylogenetic placements for taxonomic assignment of environmental DNA. J Eukaryot Microbiol 2023; 70:e12990. [PMID: 37448139 DOI: 10.1111/jeu.12990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/29/2023] [Accepted: 06/17/2023] [Indexed: 07/15/2023]
Abstract
Taxonomic assignment of operational taxonomic units (OTUs) is an important bioinformatics step in analyzing environmental sequencing data. Pairwise alignment and phylogenetic-placement methods represent two alternative approaches to taxonomic assignments, but their results can differ. Here we used available colpodean ciliate OTUs from forest soils to compare the taxonomic assignments of VSEARCH (which performs pairwise alignments) and EPA-ng (which performs phylogenetic placements). We showed that when there are differences in taxonomic assignments between pairwise alignments and phylogenetic placements at the subtaxon level, there is a low pairwise similarity of the OTUs to the reference database. We then showcase how the output of EPA-ng can be further evaluated using GAPPA to assess the taxonomic assignments when there exist multiple equally likely placements of an OTU, by taking into account the sum over the likelihood weights of the OTU placements within a subtaxon, and the branch distances between equally likely placement locations. We also inferred the evolutionary and ecological characteristics of the colpodean OTUs using their placements within subtaxa. This study demonstrates how to fully analyze the output of EPA-ng, by using GAPPA in conjunction with knowledge of the taxonomic diversity of the clade of interest.
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Affiliation(s)
- Isabelle Ewers
- Eukaryotic Microbiology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Lubomír Rajter
- Eukaryotic Microbiology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
- Phycology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Lucas Czech
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California, USA
| | - Frédéric Mahé
- CIRAD, UMR PHIM, Montpellier, France
- PHIM Plant Health Institute, CIRAD, INRAE, Institut Agro, IRD, University of Montpellier, Montpellier, France
| | - Alexandros Stamatakis
- Computational Molecular Evolution Group, Heidelberg Institute for Theoretical Studies, Heidelberg, Germany
- Institute for Theoretical Informatics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Micah Dunthorn
- Natural History Museum, University of Oslo, Oslo, Norway
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3
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Li B, Song Y, Hao T, Wang L, Zheng W, lyu Z, Chen Y, Pan X. Insights into the phylogeny of the ciliate of class Colpodea based on multigene data. Ecol Evol 2022; 12:e9380. [PMID: 36304093 PMCID: PMC9595136 DOI: 10.1002/ece3.9380] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 08/29/2022] [Accepted: 09/15/2022] [Indexed: 11/26/2022] Open
Abstract
In the class Colpodea, there are many unresolved evolutionary relationships among taxa. Here, we report 30 new sequences including SSU-rRNA, ITS1-5.8S- ITS2 rRNA, and the mitochondrial small subunit ribosomal RNA (mtSSU-rRNA) genes of five colpodeans, and conduct phylogenetic analyses based on each individual gene and a two-gene concatenated dataset. For the first time, multi-genes were used to analyze phylogenetic relationships in the class Colpodea. The main findings are: (1) SSU-rRNA, ITS1-5.8S- ITS2 rRNA, and mtSSU-rRNA gene sequences of C. reniformis and C. grandis are provided for the first time, and these two species group into the clade including C. inflata, C. lucida, C. cucullus, and C. henneguyi; (2) clustering pattern and morphological similarity indicate that Bresslauides discoideus has a close relation with Colpodidae spp.; (3) Emarginatophrya genus diagnosis is improved to be 'Hausmanniellidae with sharply shortened and isometric leftmost 1-4 ciliary rows' and Colpoda elliotti is transferred to Emarginatophrya; (4) the genus Colpoda is still non-monophyletic with the addition of 10 populations from five Colpoda species sequences, but there are only two Colpoda groups left based on the present work: Group I comprises C. inflata, C. lucida, C. cucullus, C. henneguyi, C. reniformis, and C. grandis, Group II comprises C. maupasi and C. ecaudata, and the presence of diagonal grooves and the way the vestibular opens might be the two key features that differentiates Colpoda species groups; (5) a close molecular relationship, and highly similar merotelokinetal mode, somatic ciliary pattern, and basic organization of the oral apparatus with P. steinii suggests Bromeliothrix metopoides should be temporarily assigned to Colpodidae.
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Affiliation(s)
- Bailin Li
- Key Laboratory of Biodiversity of Aquatic OrganismsHarbin Normal University HarbinHarbinP. R. China
| | - Yumeng Song
- Key Laboratory of Biodiversity of Aquatic OrganismsHarbin Normal University HarbinHarbinP. R. China
| | - Tingting Hao
- Key Laboratory of Biodiversity of Aquatic OrganismsHarbin Normal University HarbinHarbinP. R. China
| | - Li Wang
- Key Laboratory of Biodiversity of Aquatic OrganismsHarbin Normal University HarbinHarbinP. R. China
| | - Weibin Zheng
- Key Laboratory of Biodiversity of Aquatic OrganismsHarbin Normal University HarbinHarbinP. R. China
| | - Zhao lyu
- College of Life SciencesNorthwest UniversityXi'anChina
| | - Ying Chen
- School of Civil and Environmental EngineeringHarbin Institute of Technology (Shenzhen)ShenzhenChina
| | - Xuming Pan
- Key Laboratory of Biodiversity of Aquatic OrganismsHarbin Normal University HarbinHarbinP. R. China
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Wang C, Hu Y, Warren A, Hu X. Genetic Diversity and Phylogeny of the Genus Euplotes (Protozoa, Ciliophora) Revealed by the Mitochondrial CO1 and Nuclear Ribosomal Genes. Microorganisms 2021; 9:microorganisms9112204. [PMID: 34835330 PMCID: PMC8624429 DOI: 10.3390/microorganisms9112204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/03/2021] [Accepted: 10/19/2021] [Indexed: 11/16/2022] Open
Abstract
Nuclear ribosomal and mitochondrial genes have been utilized individually or in combination to identify known species and discriminate closely related species. However, compared with metazoans, genetic diversity within the ciliate order Euplotida is poorly known. The aim of this study is to investigate how much nucleotide sequence divergence occurs within Euplotes. A total of 14 new gene sequences, comprising four SSU rDNA and 10 CO1 (including three species for the first time) were obtained. Phylogenetic analyses were carried out based on sequences of two DNA fragments from the same 27 isolates. We found that CO1 revealed a larger interspecific divergence than the SSU rRNA gene, thus demonstrating a higher resolution for separating congeners. Genetic distances differ significantly at the species level. Euplotes balteatus was revealed to have a large intraspecific variation at two loci, while E. vannus showed different levels of haplotype variability, which appeared as a polyphyletic cluster on the CO1 tree. These high genetic divergences suggest the presence of more cryptic species. By contrast, the CO1 gene showed low variability within E. raikovi, appearing as monophyletic clusters, which indicates that this species could be identified based on this gene. Conclusively, CO1 is a suitable marker for the study of genetic diversity within Euplotes, and increased taxon sampling gives an opportunity to screen relationships among members of this genus. Additionally, current data present no clear biogeographical pattern for Euplotes.
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Affiliation(s)
- Congcong Wang
- Key Laboratory of Mariculture, Ministry of Education, College of Fisheries, Ocean University of China, Qingdao 266003, China;
| | - Yue Hu
- Oxford Sixth Form College, Oxford OX1 4HT, UK;
| | - Alan Warren
- Department of Life Sciences, Natural History Museum, London SW7 5BD, UK;
| | - Xiaozhong Hu
- Key Laboratory of Mariculture, Ministry of Education, College of Fisheries, Ocean University of China, Qingdao 266003, China;
- Correspondence: ; Tel.: +86-532-8203-1610
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Rajter Ľ, Ewers I, Graupner N, Vďačný P, Dunthorn M. Colpodean ciliate phylogeny and reference alignments for phylogenetic placements. Eur J Protistol 2020; 77:125747. [PMID: 33279755 DOI: 10.1016/j.ejop.2020.125747] [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: 07/22/2020] [Revised: 09/24/2020] [Accepted: 11/03/2020] [Indexed: 10/23/2022]
Abstract
The Colpodea form a major clade of ciliates that are often found in environmental DNA sequencing studies. They are united by similar somatic ciliature, but differentiated by complex oral structures. Although there are four well supported colpodean subclades, there is disagreement in molecular phylogenetic inferences about their branching order. Using available nuclear SSU-rRNA sequences, we evaluated if the bursariomorphids or the platyophryids are sister to the remaining colpodeans. We inferred the "platyophryids-early" topologies using different alignment and masking methods, but constrained analyses could not reject the "bursariomorphids-early" topology. Both bursariomorphids and platyophryids clades have a similar number of nucleotide positions shared with the outgroup, and both are interconnected with the outgroup in phylogenetic networks. Based on these discordant results, it is hard to determine which clade branched off first, although the "platyophryids-early topology" is also supported by mitochondrial SSU-rRNA data. We also offer different reference alignments that can be used to phylogenetically place short- and long-read data from environmental DNA sequencing studies, and we propose some tentative evolutionary and ecological interpretations of those placements.
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Affiliation(s)
- Ľubomír Rajter
- Eukaryotic Microbiology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany.
| | - Isabelle Ewers
- Eukaryotic Microbiology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Nadine Graupner
- Eukaryotic Microbiology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Peter Vďačný
- Department of Zoology, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovak Republic
| | - Micah Dunthorn
- Eukaryotic Microbiology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany; Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen, Essen, Germany
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6
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Wang Y, Jiang Y, Liu Y, Li Y, Katz LA, Gao F, Yan Y. Comparative Studies on the Polymorphism and Copy Number Variation of mtSSU rDNA in Ciliates (Protista, Ciliophora): Implications for Phylogenetic, Environmental, and Ecological Research. Microorganisms 2020; 8:E316. [PMID: 32106521 PMCID: PMC7142639 DOI: 10.3390/microorganisms8030316] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 02/20/2020] [Accepted: 02/21/2020] [Indexed: 01/21/2023] Open
Abstract
While nuclear small subunit ribosomal DNA (nSSU rDNA) is the most commonly-used gene marker in studying phylogeny, ecology, abundance, and biodiversity of microbial eukaryotes, mitochondrial small subunit ribosomal DNA (mtSSU rDNA) provides an alternative. Recently, both copy number variation and sequence variation of nSSU rDNA have been demonstrated for diverse organisms, which can contribute to misinterpretation of microbiome data. Given this, we explore patterns for mtSSU rDNA among 13 selected ciliates (representing five classes), a major component of microbial eukaryotes, estimating copy number and sequence variation and comparing to that of nSSU rDNA. Our study reveals: (1) mtSSU rDNA copy number variation is substantially lower than that for nSSU rDNA; (2) mtSSU rDNA copy number ranges from 1.0 × 104 to 8.1 × 105; (3) a most common sequence of mtSSU rDNA is also found in each cell; (4) the sequence variation of mtSSU rDNA are mainly indels in poly A/T regions, and only half of species have sequence variation, which is fewer than that for nSSU rDNA; and (5) the polymorphisms between haplotypes of mtSSU rDNA would not influence the phylogenetic topology. Together, these data provide more insights into mtSSU rDNA as a powerful marker especially for microbial ecology studies.
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Affiliation(s)
- Yurui Wang
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China; (Y.W.); (Y.J.); (Y.L.); (Y.L.); (F.G.)
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China
| | - Yaohan Jiang
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China; (Y.W.); (Y.J.); (Y.L.); (Y.L.); (F.G.)
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China
| | - Yongqiang Liu
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China; (Y.W.); (Y.J.); (Y.L.); (Y.L.); (F.G.)
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China
| | - Yuan Li
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China; (Y.W.); (Y.J.); (Y.L.); (Y.L.); (F.G.)
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China
| | - Laura A. Katz
- Department of Biological Sciences, Smith College, Northampton, MA 01063, USA;
| | - Feng Gao
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China; (Y.W.); (Y.J.); (Y.L.); (Y.L.); (F.G.)
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China
| | - Ying Yan
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China; (Y.W.); (Y.J.); (Y.L.); (Y.L.); (F.G.)
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China
- Department of Biological Sciences, Smith College, Northampton, MA 01063, USA;
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Zhang T, Fan X, Gao F, Al-Farraj SA, El-Serehy HA, Song W. Further analyses on the phylogeny of the subclass Scuticociliatia (Protozoa, Ciliophora) based on both nuclear and mitochondrial data. Mol Phylogenet Evol 2019; 139:106565. [PMID: 31326515 DOI: 10.1016/j.ympev.2019.106565] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 07/13/2019] [Accepted: 07/17/2019] [Indexed: 11/24/2022]
Abstract
So far, the phylogenetic studies on ciliated protists have mainly based on single locus, the nuclear ribosomal DNA (rDNA). In order to avoid the limitations of single gene/genome trees and to add more data to systematic analyses, information from mitochondrial DNA sequence has been increasingly used in different lineages of ciliates. The systematic relationships in the subclass Scuticociliatia are extremely confused and largely unresolved based on nuclear genes. In the present study, we have characterized 72 new sequences, including 40 mitochondrial cytochrome oxidase c subunit I (COI) sequences, 29 mitochondrial small subunit ribosomal DNA (mtSSU-rDNA) sequences and three nuclear small subunit ribosomal DNA (nSSU-rDNA) sequences from 47 isolates of 44 morphospecies. Phylogenetic analyses based on single gene as well as concatenated data were performed and revealed: (1) compared to mtSSU-rDNA, COI gene reveals more consistent relationships with those of nSSU-rDNA; (2) the secondary structures of mtSSU-rRNA V4 region are predicted and compared in scuticociliates, which can contribute to discrimination of closely related species; (3) neither nuclear nor mitochondrial data support the monophyly of the order Loxocephalida, which may represent some divergent and intermediate lineages between the subclass Scuticociliatia and Hymenostomatia; (4) the assignments of thigmotrichids to the order Pleuronematida and the confused taxon Sulcigera comosa to the genus Histiobalantium are confirmed by mitochondrial genes; (5) both nuclear and mitochondrial data reveal that the species in the family Peniculistomatidae always group in the genus Pleuronema, suggesting that peniculistomatids are more likely evolved from Pleuronema-like ancestors; (6) mitochondrial genes support the monophyly of the order Philasterida, but the relationships among families of the order Philasterida remain controversial due to the discrepancies between their morphological and molecular data.
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Affiliation(s)
- Tengteng Zhang
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China; Key Laboratory of Mariculture (Ocean University of China), Ministry of Education, 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; Key Laboratory of Mariculture (Ocean University of China), Ministry of Education, Qingdao 266003, China.
| | - Saleh A Al-Farraj
- Zoology Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| | - Hamed A El-Serehy
- Zoology Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| | - Weibo Song
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China; Key Laboratory of Mariculture (Ocean University of China), Ministry of Education, Qingdao 266003, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266003, China.
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Vd’ačný P, Foissner W. Re-analysis of the 18S rRNA gene phylogeny of the ciliate class Colpodea. Eur J Protistol 2019; 67:89-105. [DOI: 10.1016/j.ejop.2018.11.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 11/20/2018] [Accepted: 11/28/2018] [Indexed: 10/27/2022]
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Li M, Wang R, Bastos Gomes G, Zou H, Li WX, Wu SG, Wang GT, Ponce-Gordo F. Epidemiology and identification of two species of Chilodonella affecting farmed fishes in China. Vet Parasitol 2018; 264:8-17. [PMID: 30503097 DOI: 10.1016/j.vetpar.2018.10.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 10/08/2018] [Accepted: 10/09/2018] [Indexed: 10/28/2022]
Abstract
The genus Chilodonella includes free-living ciliated protozoa as well as pathogenic species for freshwater fish, with Chilodonella hexasticha and Chilodonella piscicola being the most important ones. These parasites cause outbreaks with high mortalities among farmed freshwater fishes with great economic losses. There are few reports of these species in China, and their identification has been based mostly on their morphological characteristics. In the present work, the parasites causing five outbreaks occurring in China between 2014 and 2017 have been identified by morphological and genetic analysis. We provide the first records of Ctenopharingodon idella and Siniperca chuatsi as hosts of C. hexasticha, and of Procypris rabaudi and Schizothorax wangchiachii as hosts of C. piscicola. There are no differences in the gross pathological findings produced by C. hexasticha and C. piscicola, consisting in desquamation and necrosis of epithelial cells in the skin and gills and in severe fusion of gill lamellae. However, both species differ in their geographic distribution: C. piscicola was found in farms located at altitudes over 1500 m above sea level and with a water temperature ≤18 °C, while C. hexasticha was found in farms located at altitudes under 50 m above sea level and with a water temperature ≥21 °C. Present results confirm that C. hexasticha and C. piscicola are two different species that can be differenced by their morphology; however, their biological variability may lead to erroneous identifications and the diagnosis should be preferably based in genetic analysis including nuclear LSU rDNA and mitochondrial SSU rDNA sequences.
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Affiliation(s)
- Ming Li
- Key Laboratory of Aquaculture Disease Control, Ministry of Agriculture, and State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Runqiu Wang
- Key Laboratory of Aquaculture Disease Control, Ministry of Agriculture, and State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Giana Bastos Gomes
- Tropical Research Institute, James Cook University Singapore, Singapore 387380, Singapore
| | - Hong Zou
- Key Laboratory of Aquaculture Disease Control, Ministry of Agriculture, and State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Wen-Xiang Li
- Key Laboratory of Aquaculture Disease Control, Ministry of Agriculture, and State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Shan-Gong Wu
- Key Laboratory of Aquaculture Disease Control, Ministry of Agriculture, and State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Gui-Tang Wang
- Key Laboratory of Aquaculture Disease Control, Ministry of Agriculture, and State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
| | - Francisco Ponce-Gordo
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, Plaza Ramón y Cajal s/n, 28040 Madrid, Spain.
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Vďačný P, Rajter Ľ, Stoeck T, Foissner W. A Proposed Timescale for the Evolution of Armophorean Ciliates: Clevelandellids Diversify More Rapidly Than Metopids. J Eukaryot Microbiol 2018; 66:167-181. [PMID: 29873141 DOI: 10.1111/jeu.12641] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 05/11/2018] [Accepted: 06/01/2018] [Indexed: 11/30/2022]
Abstract
Members of the class Armophorea occur in microaerophilic and anaerobic habitats, including the digestive tract of invertebrates and vertebrates. Phylogenetic kinships of metopid and clevelandellid armophoreans conflict with traditional morphology-based classifications. To reconcile their relationships and understand their morphological evolution and diversification, we utilized the molecular clock theory as well as information contained in the estimated time trees and morphology of extant taxa. The radiation of the last common ancestor of metopids and clevelandellids very likely occurred during the Paleozoic and crown diversification of the endosymbiotic clevelandellids dates back to the Mesozoic. According to diversification analyses, endosymbiotic clevelandellids have higher net diversification rates than predominantly free-living metopids. Their cladogenic success was very likely associated with sharply isolated ecological niches constituted by their hosts. Conflicts between traditional classifications and molecular phylogenies of metopids and clevelandellids very likely come from processes, leading to further diversification without extinction of ancestral lineages as well as from morphological plesiomorphies incorrectly classified as apomorphies. Our study thus suggests that diversification processes and reconstruction of ancestral morphologies improve the understanding of paraphyly which occurs in groups of organisms with an apparently long evolutionary history and when speciation prevails over extinction.
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Affiliation(s)
- Peter Vďačný
- Department of Zoology, Comenius University in Bratislava, Bratislava, Slovakia
| | - Ľubomír Rajter
- Department of Zoology, Comenius University in Bratislava, Bratislava, Slovakia
| | - Thorsten Stoeck
- Department of Ecology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Wilhelm Foissner
- FB Ecology and Evolution, University of Salzburg, Salzburg, Austria
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11
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Dunthorn M, Zufall RA, Chi J, Paszkiewicz K, Moore K, Mahé F. Meiotic Genes in Colpodean Ciliates Support Secretive Sexuality. Genome Biol Evol 2018; 9:1781-1787. [PMID: 28854634 PMCID: PMC5570047 DOI: 10.1093/gbe/evx125] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2017] [Indexed: 12/19/2022] Open
Abstract
The putatively asexual Colpodean ciliates potentially pose a problem to macro-organismic theories of evolution. They are extremely ancient (although asexuality is thought to hasten extinction), and yet there is one apparently derived sexual species (implying an unlikely regain of a complex trait). If macro-organismic theories of evolution also broadly apply to microbial eukaryotes, though, then most or all of the colpodean ciliates should merely be secretively sexual. Here we show using de novo genome sequencing, that colpodean ciliates have the meiotic genes required for sex and these genes are under functional constraint. Along with these genomic data, we argue that these ciliates are sexual given the cytological observations of both micronuclei and macronuclei within their cells, and the behavioral observations of brief fusions as if the cells were mating. The challenge that colpodean ciliates pose is therefore not to evolutionary theory, but to our ability to induce microbial eukaryotic sex in the laboratory.
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Affiliation(s)
- Micah Dunthorn
- Department of Ecology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Rebecca A Zufall
- Department of Biology and Biochemistry, University of Houston, Houston, TX
| | - Jingyun Chi
- Department of Ecology, University of Kaiserslautern, Kaiserslautern, Germany
| | | | - Karen Moore
- Biosciences, University of Exeter, Exeter, United Kingdom
| | - Frédéric Mahé
- Department of Ecology, University of Kaiserslautern, Kaiserslautern, Germany.,CIRAD, UMR LSTM, Montpellier, France
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12
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Pan H, Stoeck T. Redescription of the halophile ciliate, Blepharisma halophilum Ruinen, 1938 (Ciliophora, Heterotrichea, Heterotrichida) shows that the genus Blepharisma is non-monophyletic. Eur J Protistol 2017; 61:20-28. [DOI: 10.1016/j.ejop.2017.07.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 07/17/2017] [Accepted: 07/19/2017] [Indexed: 10/19/2022]
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13
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Raja R, Hemaiswarya S, Ganesan V, Carvalho IS. Internal Transcribed sequence (ITS) of Halocafeteria seosinensis (Bicosoecids). BENI-SUEF UNIVERSITY JOURNAL OF BASIC AND APPLIED SCIENCES 2017. [DOI: 10.1016/j.bjbas.2017.04.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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14
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Seah BKB, Schwaha T, Volland JM, Huettel B, Dubilier N, Gruber-Vodicka HR. Specificity in diversity: single origin of a widespread ciliate-bacteria symbiosis. Proc Biol Sci 2017; 284:20170764. [PMID: 28701560 PMCID: PMC5524500 DOI: 10.1098/rspb.2017.0764] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 06/06/2017] [Indexed: 12/03/2022] Open
Abstract
Symbioses between eukaryotes and sulfur-oxidizing (thiotrophic) bacteria have convergently evolved multiple times. Although well described in at least eight classes of metazoan animals, almost nothing is known about the evolution of thiotrophic symbioses in microbial eukaryotes (protists). In this study, we characterized the symbioses between mouthless marine ciliates of the genus Kentrophoros, and their thiotrophic bacteria, using comparative sequence analysis and fluorescence in situ hybridization. Ciliate small-subunit rRNA sequences were obtained from 17 morphospecies collected in the Mediterranean and Caribbean, and symbiont sequences from 13 of these morphospecies. We discovered a new Kentrophoros morphotype where the symbiont-bearing surface is folded into pouch-like compartments, illustrating the variability of the basic body plan. Phylogenetic analyses revealed that all investigated Kentrophoros belonged to a single clade, despite the remarkable morphological diversity of these hosts. The symbionts were also monophyletic and belonged to a new clade within the Gammaproteobacteria, with no known cultured representatives. Each host morphospecies had a distinct symbiont phylotype, and statistical analyses revealed significant support for host-symbiont codiversification. Given that these symbioses were collected from two widely separated oceans, our results indicate that symbiotic associations in unicellular hosts can be highly specific and stable over long periods of evolutionary time.
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Affiliation(s)
- Brandon K B Seah
- Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany
| | - Thomas Schwaha
- Department of Integrative Zoology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
| | - Jean-Marie Volland
- Department of Limnology and Bio-Oceanography, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
| | - Bruno Huettel
- Max Planck Genome Centre Cologne, Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Cologne, Germany
| | - Nicole Dubilier
- Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany
- MARUM, Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany
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15
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Further consideration on the phylogeny of the Ciliophora: Analyses using both mitochondrial and nuclear data with focus on the extremely confused class Phyllopharyngea. Mol Phylogenet Evol 2017; 112:96-106. [DOI: 10.1016/j.ympev.2017.04.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 04/11/2017] [Accepted: 04/20/2017] [Indexed: 11/17/2022]
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16
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Bastos Gomes G, Miller TL, Vaughan DB, Jerry DR, McCowan C, Bradley TL, Hutson KS. Evidence of multiple species of Chilodonella (Protozoa, Ciliophora) infecting Australian farmed freshwater fishes. Vet Parasitol 2017; 237:8-16. [DOI: 10.1016/j.vetpar.2017.03.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 02/16/2017] [Accepted: 03/03/2017] [Indexed: 01/20/2023]
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17
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Tarcz S, Rautian M, Potekhin A, Sawka N, Beliavskaya A, Kiselev A, Nekrasova I, Przyboś E. Paramecium putrinum (Ciliophora, Protozoa): The first insight into the variation of two DNA fragments – Molecular support for the existence of cryptic species. Mol Phylogenet Evol 2014; 73:140-5. [DOI: 10.1016/j.ympev.2014.01.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 01/18/2014] [Accepted: 01/21/2014] [Indexed: 11/25/2022]
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18
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Bourland WA, Wendell L, Hampikian G, Vďačný P. Morphology and phylogeny of Bryophryoides ocellatus n. g., n. sp. (Ciliophora, Colpodea) from in situ soil percolates of Idaho, U.S.A. Eur J Protistol 2014; 50:47-67. [DOI: 10.1016/j.ejop.2013.09.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 08/31/2013] [Accepted: 09/18/2013] [Indexed: 11/28/2022]
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19
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Dunthorn M, Otto J, Berger SA, Stamatakis A, Mahé F, Romac S, de Vargas C, Audic S, Stock A, Kauff F, Stoeck T. Placing environmental next-generation sequencing amplicons from microbial eukaryotes into a phylogenetic context. Mol Biol Evol 2014; 31:993-1009. [PMID: 24473288 DOI: 10.1093/molbev/msu055] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Nucleotide positions in the hypervariable V4 and V9 regions of the small subunit (SSU)-rDNA locus are normally difficult to align and are usually removed before standard phylogenetic analyses. Yet, with next-generation sequencing data, amplicons of these regions are all that are available to answer ecological and evolutionary questions that rely on phylogenetic inferences. With ciliates, we asked how inclusion of the V4 or V9 regions, regardless of alignment quality, affects tree topologies using distinct phylogenetic methods (including PairDist that is introduced here). Results show that the best approach is to place V4 amplicons into an alignment of full-length Sanger SSU-rDNA sequences and to infer the phylogenetic tree with RAxML. A sliding window algorithm as implemented in RAxML shows, though, that not all nucleotide positions in the V4 region are better than V9 at inferring the ciliate tree. With this approach and an ancestral-state reconstruction, we use V4 amplicons from European nearshore sampling sites to infer that rather than being primarily terrestrial and freshwater, colpodean ciliates may have repeatedly transitioned from terrestrial/freshwater to marine environments.
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Affiliation(s)
- Micah Dunthorn
- Department of Ecology, University of Kaiserslautern, Kaiserslautern, Germany
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20
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Yi Z, Strüder-Kypke M, Hu X, Lin X, Song W. Sampling strategies for improving tree accuracy and phylogenetic analyses: a case study in ciliate protists, with notes on the genus Paramecium. Mol Phylogenet Evol 2013; 71:142-8. [PMID: 24315865 DOI: 10.1016/j.ympev.2013.11.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 11/20/2013] [Accepted: 11/24/2013] [Indexed: 11/28/2022]
Abstract
In order to assess how dataset-selection for multi-gene analyses affects the accuracy of inferred phylogenetic trees in ciliates, we chose five genes and the genus Paramecium, one of the most widely used model protist genera, and compared tree topologies of the single- and multi-gene analyses. Our empirical study shows that: (1) Using multiple genes improves phylogenetic accuracy, even when their one-gene topologies are in conflict with each other. (2) The impact of missing data on phylogenetic accuracy is ambiguous: resolution power and topological similarity, but not number of represented taxa, are the most important criteria of a dataset for inclusion in concatenated analyses. (3) As an example, we tested the three classification models of the genus Paramecium with a multi-gene based approach, and only the monophyly of the subgenus Paramecium is supported.
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Affiliation(s)
- Zhenzhen Yi
- Key Laboratory of Ecology and Environment Science in Guangdong Higher Education, School of Life Science, South China Normal University, Guangzhou 510631, China; Laboratory of Protozoology, Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Michaela Strüder-Kypke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario NIG 2W1, Canada
| | - Xiaozhong Hu
- Laboratory of Protozoology, Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Xiaofeng Lin
- Key Laboratory of Ecology and Environment Science in Guangdong Higher Education, School of Life Science, South China Normal University, Guangzhou 510631, China.
| | - Weibo Song
- Laboratory of Protozoology, Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China.
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21
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Przyboś E, Tarcz S, Dusi E. New Paramecium quadecaurelia strains (P. aurelia spp. complex, Ciliophora) identified by molecular markers (rDNA and mtDNA). Eur J Protistol 2013; 49:477-86. [DOI: 10.1016/j.ejop.2012.11.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 10/02/2012] [Accepted: 11/08/2012] [Indexed: 11/28/2022]
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22
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Multigene-based analyses of the phylogenetic evolution of oligotrich ciliates, with consideration of the internal transcribed spacer 2 secondary structure of three systematically ambiguous genera. EUKARYOTIC CELL 2013; 12:430-7. [PMID: 23314963 DOI: 10.1128/ec.00270-12] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Oligotrichs are ciliates of great abundance, but their molecular systematics are rarely studied. In this study, nine species representing three genera (Strombidium, Novistrombidium, and Omegastrombidium) of marine oligotrich ciliates were collected from coastal waters of China. The small subunit (SSU) rRNA gene of two species and the internal transcribed spacers and 5.8S region (ITS1-5.8S-ITS2) for all nine species were sequenced for the first time. Phylogenetic trees using both the SSU rRNA gene and ITS1-5.8S-ITS2 region sequences were generated. In addition, the secondary structures of ITS2 RNA transcripts of 11 taxa representing four genera (Novistrombidium, Strombidium, Omegastrombidium, and Laboea) were investigated. The phylogenetic analyses show that (i) the family Strombidiidae is polyphyletic, (ii) the genus Novistrombidium is probably paraphyletic, containing at least two subclades, which is consistent with recent cladistic analyses based on morphological data, and (iii) the tail-less genus Laboea is separate from other genera of Strombidiidae, clustering instead with the tontoniids. Comparisons of the secondary structure of ITS2 regions also show that Laboea is clearly different from other strombidiids. These findings cast doubt on the monophyly of the family Strombidiidae.
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23
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Zhan Z, Xu K, Dunthorn M. Evaluating molecular support for and against the monophyly of the Peritrichia and phylogenetic relationships within the Mobilida (Ciliophora, Oligohymenophorea). ZOOL SCR 2012. [DOI: 10.1111/j.1463-6409.2012.00568.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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24
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Przyboś E, Tarcz S, Prajer M, Surmacz M, Rautian M, Sawka N. Does high intraspecific variability of two genome fragments indicate a recent speciation process ofParamecium dodecaurelia(P. aureliaspecies complex, Ciliophora, Protozoa)? SYST BIODIVERS 2012. [DOI: 10.1080/14772000.2012.721403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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25
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Huang J, Dunthorn M, Song W. Expanding character sampling for the molecular phylogeny of euplotid ciliates (Protozoa, Ciliophora) using three markers, with a focus on the family Uronychiidae. Mol Phylogenet Evol 2012; 63:598-605. [DOI: 10.1016/j.ympev.2012.02.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 01/05/2012] [Accepted: 02/01/2012] [Indexed: 10/28/2022]
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26
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Tarcz S, Potekhin A, Rautian M, Przyboś E. Variation in ribosomal and mitochondrial DNA sequences demonstrates the existence of intraspecific groups in Paramecium multimicronucleatum (Ciliophora, Oligohymenophorea). Mol Phylogenet Evol 2012; 63:500-9. [DOI: 10.1016/j.ympev.2012.01.024] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 01/27/2012] [Accepted: 01/31/2012] [Indexed: 11/25/2022]
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27
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Dunthorn M, Katz LA, Stoeck T, Foissner W. Congruence and indifference between two molecular markers for understanding oral evolution in the Marynidae sensu lato (Ciliophora, Colpodea). Eur J Protistol 2012; 48:297-304. [PMID: 22356924 PMCID: PMC3473355 DOI: 10.1016/j.ejop.2012.01.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2011] [Revised: 01/16/2012] [Accepted: 01/18/2012] [Indexed: 11/26/2022]
Abstract
Our understanding of the evolution of oral structures within the Colpodida is confounded by the low number of morphological characters that can be used in constructing hypotheses, and by the low taxon and character sampling in molecular phylogenetic analyses designed to assess these hypotheses. Here we increase character sampling by sequencing the mitochondrial SSU-rDNA locus for three isolates of the Marynidae sensu lato. We show that the inferred mitochondrial and nuclear SSU-rDNA trees, as well as concatenated and constrained analyses, are congruent in not recovering a monophyletic Marynidae. However, due to low node support, the trees are indifferent to whether the morphological characters used to unite the Marynidae are the result of retention of ancestral states or convergence. In light of this indifference and an increased amount of nuclear and mitochondrial SSU-rDNA data, alternative hypotheses of oral evolution in the Colpodida are presented.
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Affiliation(s)
- Micah Dunthorn
- Department of Ecology, University of Kaiserslautern, Germany.
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28
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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: 2.8] [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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29
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Abstract
Using nine new taxa and statistical inferences based on morphological and molecular data, we analyze the evolution within the class Colpodea. The molecular and cladistic analyses show four well-supported clades: platyophryids, bursariomorphids, cyrtolophosidids, and colpodids. There is a widespread occurrence of homoplasies, affecting even conspicuous morphological characteristics, e.g. the inclusion of the micronucleus in the perinuclear space of the macronucleus. The most distinct changes in the morphological classification are the lack of a basal divergence into two subclasses and the split of the cyrtolophosidids into two main clades, differing mainly by the presence vs. absence of an oral cavity. The most complex clade is that of the colpodids. We partially reconcile the morphological and molecular data using evolutionary systematics, providing a scenario in which the colpodids evolved from a Bardeliella-like ancestor and the genus Colpoda performed an intense adaptive radiation, giving rise to three main clades: Colpodina n. subord., Grossglockneriina, and Bryophryina. Three new taxa are established: Colpodina n. subord., Tillinidae n. fam., and Ottowphryidae n. fam. Colpodean evolution and classification are far from being understood because sequences are lacking for most species and half of their diversity is possibly undescribed.
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Affiliation(s)
- Wilhelm Foissner
- FB Organismische Biologie, Universität Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria.
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30
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A two-locus molecular characterization of Paramecium calkinsi. Protist 2011; 163:263-73. [PMID: 21798802 DOI: 10.1016/j.protis.2011.06.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Accepted: 06/25/2011] [Indexed: 11/23/2022]
Abstract
Paramecium calkinsi (Ciliophora, Protozoa) is a euryhaline species which was first identified in freshwater habitats, but subsequently several strains were also collected from brackish water. It is characterized by clockwise spiral swimming movement and the general morphology of the "bursaria type." The present paper is the first molecular characterization of P. calkinsi strains recently collected in distant regions in Russia using ITS1-5.8S- ITS2-5'LSU rDNA (1100bp) and COI (620bp) mtDNA sequenced gene fragments. For comparison, our molecular analysis includes P. bursaria, exhibiting a similar "bursaria morphotype" as well as species representing the "aurelia type," i.e., P. caudatum, P. multimicronucleatum, P. jenningsi, and P. schewiakoffi, and some species of the P. aurelia species complex (P. primaurelia, P. tetraurelia, P. sexaurelia, and P. tredecaurelia). We also use data from GenBank concerning other species in the genus Paramecium and Tetrahymena (which used as an outgroup). The division of the genus Paramecium into four subgenera (proposed by Fokin et al. 2004) is clearly presented by the trees. There is a clear separation between P. calkinsi strains collected from different regions (races). Consequently, given the molecular distances between them, it seems that these races may represent different syngens within the species.
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