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Castelli M, Lanzoni O, Giovannini M, Lebedeva N, Gammuto L, Sassera D, Melekhin M, Potekhin A, Fokin S, Petroni G. 'Candidatus Gromoviella agglomerans', a novel intracellular Holosporaceae parasite of the ciliate Paramecium showing marked genome reduction. ENVIRONMENTAL MICROBIOLOGY REPORTS 2022; 14:34-49. [PMID: 34766443 DOI: 10.1111/1758-2229.13021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 09/14/2021] [Indexed: 06/13/2023]
Abstract
Holosporales are an alphaproteobacterial lineage encompassing bacteria obligatorily associated with multiple diverse eukaryotes. For most representatives, little is known on the interactions with their hosts. In this study, we characterized a novel Holosporales symbiont of the ciliate Paramecium polycaryum. This bacterium inhabits the host cytoplasm, frequently forming quite large aggregates. Possibly due to such aggregates, host cells sometimes displayed lethal division defects. The symbiont was also able to experimentally stably infect another Paramecium polycaryum strain. The bacterium is phylogenetically related with symbionts of other ciliates and diplonemids, forming a putatively fast-evolving clade within the family Holosporaceae. Similarly to many close relatives, it presents a very small genome (<600 kbp), and, accordingly, a limited predicted metabolism, implying a heavy dependence on Paramecium, thanks also to some specialized membrane transporters. Characterized features, including the presence of specific secretion systems, are overall suggestive of a mild parasitic effect on the host. From an evolutionary perspective, a potential ancestral trend towards pronounced genome reduction and possibly linked to parasitism could be inferred, at least among fast-evolving Holosporaceae, with some lineage-specific traits. Interestingly, similar convergent features could be observed in other host-associated lineages, in particular Rickettsiales among Alphaproteobacteria.
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Affiliation(s)
- Michele Castelli
- Dipartimento di Biologia e Biotecnologie, Università degli studi di Pavia, Pavia, Italy
| | - Olivia Lanzoni
- Dipartimento di Biologia, Università di Pisa, Pisa, Italy
- Department of Food Hygiene and Environmental Health, University of Helsinki, Helsinki, Finland
| | | | - Natalia Lebedeva
- Centre of Core Facilities "Culture Collections of Microorganisms", Saint Petersburg State University, Saint Petersburg, Russia
| | | | - Davide Sassera
- Dipartimento di Biologia e Biotecnologie, Università degli studi di Pavia, Pavia, Italy
| | - Maksim Melekhin
- Department of Microbiology, Faculty of Biology, Saint Petersburg State University, Saint Petersburg, Russia
- Laboratory of Cellular and Molecular Protistology, Zoological Institute RAS, Saint Petersburg, Russia
| | - Alexey Potekhin
- Department of Microbiology, Faculty of Biology, Saint Petersburg State University, Saint Petersburg, Russia
- Laboratory of Cellular and Molecular Protistology, Zoological Institute RAS, Saint Petersburg, Russia
| | - Sergei Fokin
- Dipartimento di Biologia, Università di Pisa, Pisa, Italy
- Department of Invertebrate Zoology, Saint Petersburg State University, Saint Petersburg, Russia
| | - Giulio Petroni
- Dipartimento di Biologia, Università di Pisa, Pisa, Italy
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2
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Fokin SI, Serra V. Bacterial Symbiosis in Ciliates (Alveolata, Ciliophora): Roads Traveled and Those Still to be Taken. J Eukaryot Microbiol 2022; 69:e12886. [PMID: 35006645 PMCID: PMC9539572 DOI: 10.1111/jeu.12886] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 11/30/2022]
Abstract
The diversity of prokaryotic symbionts in Ciliophora and other protists is fascinatingly rich; they may even include some potentially pathogenic bacteria. In this review, we summarize currently available data on biodiversity and some morphological and biological peculiarities of prokaryotic symbionts mainly within the genera Paramecium and Euplotes. Another direction of ciliate symbiology, neglected for a long time and now re‐discovered, is the study of epibionts of ciliates. This promises a variety of interesting outcomes. Last, but not least, we stress the new technologies, such as next generation sequencing and the use of genomics data, which all can clarify many new aspects of relevance. For this reason, a brief overview of achievements in genomic studies on ciliate's symbionts is provided. Summing up the results of numerous scientific contributions, we systematically update current knowledge and outline the prospects as to how symbiology of Ciliophora may develop in the near future.
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Affiliation(s)
- Sergei I Fokin
- University of Pisa, Pisa, Italy.,St. Petersburg State University, St. Petersburg, Russia
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3
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Oren A, Garrity GM, Parker CT, Chuvochina M, Trujillo ME. Lists of names of prokaryotic Candidatus taxa. Int J Syst Evol Microbiol 2020; 70:3956-4042. [DOI: 10.1099/ijsem.0.003789] [Citation(s) in RCA: 782] [Impact Index Per Article: 195.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We here present annotated lists of names of Candidatus taxa of prokaryotes with ranks between subspecies and class, proposed between the mid-1990s, when the provisional status of Candidatus taxa was first established, and the end of 2018. Where necessary, corrected names are proposed that comply with the current provisions of the International Code of Nomenclature of Prokaryotes and its Orthography appendix. These lists, as well as updated lists of newly published names of Candidatus taxa with additions and corrections to the current lists to be published periodically in the International Journal of Systematic and Evolutionary Microbiology, may serve as the basis for the valid publication of the Candidatus names if and when the current proposals to expand the type material for naming of prokaryotes to also include gene sequences of yet-uncultivated taxa is accepted by the International Committee on Systematics of Prokaryotes.
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Affiliation(s)
- Aharon Oren
- The Institute of Life Sciences, The Hebrew University of Jerusalem, The Edmond J. Safra Campus, 9190401 Jerusalem, Israel
| | - George M. Garrity
- NamesforLife, LLC, PO Box 769, Okemos MI 48805-0769, USA
- Department of Microbiology & Molecular Genetics, Biomedical Physical Sciences, Michigan State University, East Lansing, MI 48824-4320, USA
| | | | - Maria Chuvochina
- Australian Centre for Ecogenomics, University of Queensland, St. Lucia QLD 4072, Brisbane, Australia
| | - Martha E. Trujillo
- Departamento de Microbiología y Genética, Campus Miguel de Unamuno, Universidad de Salamanca, 37007, Salamanca, Spain
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4
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“Candidatus Mystax nordicus” Aggregates with Mitochondria of Its Host, the Ciliate Paramecium nephridiatum. DIVERSITY 2020. [DOI: 10.3390/d12060251] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Extensive search for new endosymbiotic systems in ciliates occasionally reverts us to the endosymbiotic bacteria described in the pre-molecular biology era and, hence, lacking molecular characterization. A pool of these endosymbionts has been referred to as a hidden bacterial biodiversity from the past. Here, we provide a description of one of such endosymbionts, retrieved from the ciliate Paramecium nephridiatum. This curve-shaped endosymbiont (CS), which shared the host cytoplasm with recently described “Candidatus Megaira venefica”, was found in the same host and in the same geographic location as one of the formerly reported endosymbiotic bacteria and demonstrated similar morphology. Based on morphological data obtained with DIC, TEM and AFM and molecular characterization by means of sequencing 16S rRNA gene, we propose a novel genus, “Candidatus Mystax”, with a single species “Ca. Mystax nordicus”. Phylogenetic analysis placed this species in Holosporales, among Holospora-like bacteria. Contrary to all Holospora species and many other Holospora-like bacteria, such as “Candidatus Gortzia”, “Candidatus Paraholospora” or “Candidatus Hafkinia”, “Ca. Mystax nordicus” was never observed inside the host nucleus. “Ca. Mystax nordicus” lacked infectivity and killer effect. The striking peculiarity of this endosymbiont was its ability to form aggregates with the host mitochondria, which distinguishes it from Holospora and Holospora-like bacteria inhabiting paramecia.
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5
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Zhao W, Li M, Xiong F, Zhang D, Wu S, Zou H, Li W, Wang G. Identification of Intracellular Bacteria in the Ciliate
Balantidium ctenopharyngodoni
(Ciliophora, Litostomatea). J Eukaryot Microbiol 2020; 67:417-426. [DOI: 10.1111/jeu.12791] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 01/09/2020] [Accepted: 02/06/2020] [Indexed: 11/27/2022]
Affiliation(s)
- Weishan Zhao
- 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
- University of Chinese Academy of Sciences Beijing 100049 China
| | - 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
| | - Fan Xiong
- 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
| | - Dong Zhang
- 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
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Shangong 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
| | - 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
| | - Wenxiang 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
| | - Guitang 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
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6
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Epidemiology of Nucleus-Dwelling Holospora: Infection, Transmission, Adaptation, and Interaction with Paramecium. Results Probl Cell Differ 2020; 69:105-135. [PMID: 33263870 DOI: 10.1007/978-3-030-51849-3_4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The chapter describes the exceptional symbiotic associations formed between the ciliate Paramecium and Holospora, highly infectious bacteria residing in the host nuclei. Holospora and Holospora-like bacteria (Alphaproteobacteria) are characterized by their ability for vertical and horizontal transmission in host populations, a complex biphasic life cycle, and pronounced preference for host species and colonized cell compartment. These bacteria are obligate intracellular parasites; thus, their metabolic repertoire is dramatically reduced. Nevertheless, they perform complex interactions with the host ciliate. We review ongoing efforts to unravel the molecular adaptations of these bacteria to their unusual lifestyle and the host's employment in the symbiosis. Furthermore, we summarize current knowledge on the genetic and genomic background of Paramecium-Holospora symbiosis and provide insights into the ecological and evolutionary consequences of this interaction. The diversity and occurrence of symbioses between ciliates and Holospora-like bacteria in nature is discussed in connection with transmission modes of symbionts, host specificity and compatibility of the partners. We aim to summarize 50 years of research devoted to these symbiotic systems and conclude trying to predict some perspectives for further studies.
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7
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Potekhin A, Schweikert M, Nekrasova I, Vitali V, Schwarzer S, Anikina A, Kaltz O, Petroni G, Schrallhammer M. Complex life cycle, broad host range and adaptation strategy of the intranuclear Paramecium symbiont Preeria caryophila comb. nov. FEMS Microbiol Ecol 2019; 94:4987202. [PMID: 29718229 DOI: 10.1093/femsec/fiy076] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Accepted: 04/24/2018] [Indexed: 01/18/2023] Open
Abstract
Holospora and related bacteria are a group of obligate Paramecium symbionts. Characteristic features are their infectivity, the presence of two distinct morphotypes, and usually a strict specialization for a single Paramecium species as host and for a nuclear compartment (either somatic or generative nucleus) for reproduction. Holospora caryophila steps out of line, naturally occurring in Paramecium biaurelia and Paramecium caudatum. This study addresses the phylogenetic relationship among H. caryophila and other Holospora species based on 16S rRNA gene sequence comparison analyzing the type strain and seven new macronuclear symbionts. Key aspects of Holospora physiology such as infectivity, symbiosis establishment and host range were determined by comprehensive infection assays. Detailed morphological investigations and sequence-based phylogeny confirmed a high similarity between the type strain of H. caryophila and the novel strains. Surprisingly, they are only distantly related to other Holospora species suggesting that they belong to a new genus within the family Holosporaceae, here described as Preeria caryophila comb. nov. Adding to this phylogenetic distance, we also observed a much broader host range, comprising at least eleven Paramecium species. As these potential host species exhibit substantial differences in frequency of sexual processes, P. caryophila demonstrates which adaptations are crucial for macronuclear symbionts facing regular destruction of their habitat.
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Affiliation(s)
- Alexey Potekhin
- Department of Microbiology, Faculty of Biology, Saint Petersburg State University, 190020 Saint Petersburg, Russia
| | - Michael Schweikert
- Biobased Materials Group, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, 70569 Stuttgart, Germany
| | - Irina Nekrasova
- Department of Microbiology, Faculty of Biology, Saint Petersburg State University, 190020 Saint Petersburg, Russia
| | - Valerio Vitali
- Department of Biology, Università di Pisa, 56126 Pisa, Italy
| | - Sabine Schwarzer
- Microbiology, Institute of Biology II, Albert-Ludwigs Universität Freiburg, 79104 Freiburg, Germany
| | - Arina Anikina
- Department of Microbiology, Faculty of Biology, Saint Petersburg State University, 190020 Saint Petersburg, Russia
| | - Oliver Kaltz
- Institut des Sciences de l'Evolution Montpellier, Université de Montpellier, 34090 Montpellier, France
| | - Giulio Petroni
- Department of Biology, Università di Pisa, 56126 Pisa, Italy
| | - Martina Schrallhammer
- Department of Biology, Università di Pisa, 56126 Pisa, Italy.,Microbiology, Institute of Biology II, Albert-Ludwigs Universität Freiburg, 79104 Freiburg, Germany
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8
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Detection of a new bacterium of the family Holosporaceae (Alphaproteobacteria: Holosporales) associated with the oribatid mite Achipteria coleoptrata. Biologia (Bratisl) 2019. [DOI: 10.2478/s11756-019-00251-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
AbstractWe detected an unknown bacterium in Achipteria coleoptrata (Acari: Oribatida). Its 16S rDNA gene sequence showed 89% identity to the endosymbiont “Candidatus Nucleicultrix amoebiphila” from amoebae and “Candidatus Gortzia sp.” from ciliates. Phylogenetic analysis revealed that the microorganism is a member of the family Holosporaceae, order Holosporales of Alphaproteobacteria. Its occurrence in Oribatida is enigmatic. It cannot be excluded that it is a symbiont of Oribatida as well as it is an endosymbiont of a smaller, even unicellular, organisms living inside the mite. The issue of the occurrence of this microorganism is interesting and further research is needed to gain the knowledge of its role and the nature of bacterium-host interaction.
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9
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Muñoz-Gómez SA, Hess S, Burger G, Lang BF, Susko E, Slamovits CH, Roger AJ. An updated phylogeny of the Alphaproteobacteria reveals that the parasitic Rickettsiales and Holosporales have independent origins. eLife 2019; 8:e42535. [PMID: 30789345 PMCID: PMC6447387 DOI: 10.7554/elife.42535] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 02/21/2019] [Indexed: 11/13/2022] Open
Abstract
The Alphaproteobacteria is an extraordinarily diverse and ancient group of bacteria. Previous attempts to infer its deep phylogeny have been plagued with methodological artefacts. To overcome this, we analyzed a dataset of 200 single-copy and conserved genes and employed diverse strategies to reduce compositional artefacts. Such strategies include using novel dataset-specific profile mixture models and recoding schemes, and removing sites, genes and taxa that are compositionally biased. We show that the Rickettsiales and Holosporales (both groups of intracellular parasites of eukaryotes) are not sisters to each other, but instead, the Holosporales has a derived position within the Rhodospirillales. A synthesis of our results also leads to an updated proposal for the higher-level taxonomy of the Alphaproteobacteria. Our robust consensus phylogeny will serve as a framework for future studies that aim to place mitochondria, and novel environmental diversity, within the Alphaproteobacteria.
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Affiliation(s)
- Sergio A Muñoz-Gómez
- Department of Biochemistry and Molecular BiologyDalhousie UniversityHalifaxCanada
- Centre for Comparative Genomics and Evolutionary BioinformaticsDalhousie UniversityHalifaxCanada
| | - Sebastian Hess
- Department of Biochemistry and Molecular BiologyDalhousie UniversityHalifaxCanada
- Centre for Comparative Genomics and Evolutionary BioinformaticsDalhousie UniversityHalifaxCanada
- Institute of ZoologyUniversity of CologneCologneGermany
| | - Gertraud Burger
- Department of Biochemistry, Robert-Cedergren Center in Bioinformatics and GenomicsUniversité de MontréalMontrealCanada
| | - B Franz Lang
- Department of Biochemistry, Robert-Cedergren Center in Bioinformatics and GenomicsUniversité de MontréalMontrealCanada
| | - Edward Susko
- Centre for Comparative Genomics and Evolutionary BioinformaticsDalhousie UniversityHalifaxCanada
- Department of Mathematics and StatisticsDalhousie UniversityHalifaxCanada
| | - Claudio H Slamovits
- Department of Biochemistry and Molecular BiologyDalhousie UniversityHalifaxCanada
- Centre for Comparative Genomics and Evolutionary BioinformaticsDalhousie UniversityHalifaxCanada
| | - Andrew J Roger
- Department of Biochemistry and Molecular BiologyDalhousie UniversityHalifaxCanada
- Centre for Comparative Genomics and Evolutionary BioinformaticsDalhousie UniversityHalifaxCanada
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10
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Muñoz-Gómez SA, Hess S, Burger G, Lang BF, Susko E, Slamovits CH, Roger AJ. An updated phylogeny of the Alphaproteobacteria reveals that the parasitic Rickettsiales and Holosporales have independent origins. eLife 2019; 8. [PMID: 30789345 DOI: 10.7554/elife.42535.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 02/21/2019] [Indexed: 05/20/2023] Open
Abstract
The Alphaproteobacteria is an extraordinarily diverse and ancient group of bacteria. Previous attempts to infer its deep phylogeny have been plagued with methodological artefacts. To overcome this, we analyzed a dataset of 200 single-copy and conserved genes and employed diverse strategies to reduce compositional artefacts. Such strategies include using novel dataset-specific profile mixture models and recoding schemes, and removing sites, genes and taxa that are compositionally biased. We show that the Rickettsiales and Holosporales (both groups of intracellular parasites of eukaryotes) are not sisters to each other, but instead, the Holosporales has a derived position within the Rhodospirillales. A synthesis of our results also leads to an updated proposal for the higher-level taxonomy of the Alphaproteobacteria. Our robust consensus phylogeny will serve as a framework for future studies that aim to place mitochondria, and novel environmental diversity, within the Alphaproteobacteria.
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Affiliation(s)
- Sergio A Muñoz-Gómez
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Canada
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Canada
| | - Sebastian Hess
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Canada
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Canada
- Institute of Zoology, University of Cologne, Cologne, Germany
| | - Gertraud Burger
- Department of Biochemistry, Robert-Cedergren Center in Bioinformatics and Genomics, Université de Montréal, Montreal, Canada
| | - B Franz Lang
- Department of Biochemistry, Robert-Cedergren Center in Bioinformatics and Genomics, Université de Montréal, Montreal, Canada
| | - Edward Susko
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Canada
- Department of Mathematics and Statistics, Dalhousie University, Halifax, Canada
| | - Claudio H Slamovits
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Canada
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Canada
| | - Andrew J Roger
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Canada
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Canada
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11
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Disentangling the Taxonomy of Rickettsiales and Description of Two Novel Symbionts ("Candidatus Bealeia paramacronuclearis" and "Candidatus Fokinia cryptica") Sharing the Cytoplasm of the Ciliate Protist Paramecium biaurelia. Appl Environ Microbiol 2016; 82:7236-7247. [PMID: 27742680 PMCID: PMC5118934 DOI: 10.1128/aem.02284-16] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/06/2016] [Indexed: 11/20/2022] Open
Abstract
In the past 10 years, the number of endosymbionts described within the bacterial order Rickettsiales has constantly grown. Since 2006, 18 novel Rickettsiales genera inhabiting protists, such as ciliates and amoebae, have been described. In this work, we characterize two novel bacterial endosymbionts from Paramecium collected near Bloomington, IN. Both endosymbiotic species inhabit the cytoplasm of the same host. The Gram-negative bacterium “Candidatus Bealeia paramacronuclearis” occurs in clumps and is frequently associated with the host macronucleus. With its electron-dense cytoplasm and a distinct halo surrounding the cell, it is easily distinguishable from the second smaller symbiont, “Candidatus Fokinia cryptica,” whose cytoplasm is electron lucid, lacks a halo, and is always surrounded by a symbiontophorous vacuole. For molecular characterization, the small-subunit rRNA genes were sequenced and used for taxonomic assignment as well as the design of species-specific oligonucleotide probes. Phylogenetic analyses revealed that “Candidatus Bealeia paramacronuclearis” clusters with the so-called “basal” Rickettsiales, and “Candidatus Fokinia cryptica” belongs to “Candidatus Midichloriaceae.” We obtained tree topologies showing a separation of Rickettsiales into at least two groups: one represented by the families Rickettsiaceae, Anaplasmataceae, and “Candidatus Midichloriaceae” (RAM clade), and the other represented by “basal Rickettsiales,” including “Candidatus Bealeia paramacronuclearis.” Therefore, and in accordance with recent publications, we propose to limit the order Rickettsiales to the RAM clade and to raise “basal Rickettsiales” to an independent order, Holosporales ord. nov., inside Alphaproteobacteria, which presently includes four family-level clades. Additionally, we define the family “Candidatus Hepatincolaceae” and redefine the family Holosporaceae. IMPORTANCE In this paper, we provide the characterization of two novel bacterial symbionts inhabiting the same Paramecium host (Ciliophora, Alveolata). Both symbionts belong to “traditional” Rickettsiales, one representing a new species of the genus “Candidatus Fokinia” (“Candidatus Midichloriaceae”), and the other representing a new genus of a “basal” Rickettsiales. According to newly characterized sequences and to a critical revision of recent literature, we propose a taxonomic reorganization of “traditional” Rickettsiales that we split into two orders: Rickettsiales sensu stricto and Holosporales ord. nov. This work represents a critical revision, including new records of a group of symbionts frequently occurring in protists and whose biodiversity is still largely underestimated.
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12
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Serra V, Fokin SI, Castelli M, Basuri CK, Nitla V, Verni F, Sandeep BV, Kalavati C, Petroni G. " Candidatus Gortzia shahrazadis", a Novel Endosymbiont of Paramecium multimicronucleatum and a Revision of the Biogeographical Distribution of Holospora-Like Bacteria. Front Microbiol 2016; 7:1704. [PMID: 27867371 PMCID: PMC5095128 DOI: 10.3389/fmicb.2016.01704] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 10/12/2016] [Indexed: 11/13/2022] Open
Abstract
Holospora spp. and "Candidatus Gortzia infectiva", known as Holospora-like bacteria (HLB), are commonly found as nuclear endosymbionts of ciliates, especially the Paramecium genus. HLB are related by phylogenetic relationships, morphological features, and life-cycles, which involve two alternating morphotypes: reproductive and infectious forms (RF, IF). In this paper we describe a novel species belonging to the "Ca. Gortzia" genus, detected in P. multimicronucleatum, a ciliate for which infection by an HLB has not been reported, discovered in India. This novel endosymbiont shows unusual and surprising features with respect to other HLB, such as large variations in IF morphology and the occasional ability to reproduce in the host cytoplasm. We propose the name of "Candidatus Gortzia shahrazadis" for this novel HLB. Moreover, we report two additional species of HLB from Indian Paramecium populations: "Ca. Gortzia infectiva" (from P. jenningsi), and H. obtusa (from P. caudatum); the latter is the first record of Holospora from a tropical country. Although tropical, we retrieved H. obtusa at an elevation of 706 m corresponding to a moderate climate not unlike conditions where Holospora are normally found, suggesting the genus Holospora does exist in tropical countries, but restricted to higher elevations.
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Affiliation(s)
| | - Sergei I Fokin
- Department of Biology, University of PisaPisa, Italy; Department of Invertebrate Zoology, Saint Petersburg State UniversitySaint Petersburg, Russia
| | - Michele Castelli
- Department of Biology, University of PisaPisa, Italy; Department of Veterinary Medicine, University of MilanMilan, Italy
| | - Charan K Basuri
- Department of Zoology, Andhra University Visakhapatnam, India
| | | | - Franco Verni
- Department of Biology, University of Pisa Pisa, Italy
| | - Bhagavatula V Sandeep
- Department of Zoology, Andhra UniversityVisakhapatnam, India; Department of Biotechnology, Andhra UniversityVisakhapatnam, India
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13
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Kroer P, Kjeldsen KU, Nyengaard JR, Schramm A, Funch P. A Novel Extracellular Gut Symbiont in the Marine Worm Priapulus caudatus (Priapulida) Reveals an Alphaproteobacterial Symbiont Clade of the Ecdysozoa. Front Microbiol 2016; 7:539. [PMID: 27199899 PMCID: PMC4844607 DOI: 10.3389/fmicb.2016.00539] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 04/01/2016] [Indexed: 11/29/2022] Open
Abstract
Priapulus caudatus (phylum Priapulida) is a benthic marine predatory worm with a cosmopolitan distribution. In its digestive tract we detected symbiotic bacteria that were consistently present in specimens collected over 8 years from three sites at the Swedish west coast. Based on their 16S rRNA gene sequence, these symbionts comprise a novel genus of the order Rickettsiales (Alphaproteobacteria). Electron microscopy and fluorescence in situ hybridization (FISH) identified them as extracellular, elongate bacteria closely associated with the microvilli, for which we propose the name “Candidatus Tenuibacter priapulorum”. Within Rickettsiales, they form a phylogenetically well-defined, family-level clade with uncultured symbionts of marine, terrestrial, and freshwater arthropods. Cand. Tenuibacter priapulorum expands the host range of this candidate family from Arthropoda to the entire Ecdysozoa, which may indicate an evolutionary adaptation of this bacterial group to the microvilli-lined guts of the Ecdysozoa.
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Affiliation(s)
- Paul Kroer
- Section for Genetics, Ecology, and Evolution, Department of Bioscience, Aarhus University Aarhus, Denmark
| | - Kasper U Kjeldsen
- Section for Microbiology and Center for Geomicrobiology, Department of Bioscience, Aarhus University Aarhus, Denmark
| | - Jens R Nyengaard
- Stereology and Electron Microscopy Laboratory, Department of Clinical Medicine, Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University Aarhus, Denmark
| | - Andreas Schramm
- Section for Microbiology and Center for Geomicrobiology, Department of Bioscience, Aarhus University Aarhus, Denmark
| | - Peter Funch
- Section for Genetics, Ecology, and Evolution, Department of Bioscience, Aarhus University Aarhus, Denmark
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14
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Szokoli F, Sabaneyeva E, Castelli M, Krenek S, Schrallhammer M, Soares CAG, da Silva-Neto ID, Berendonk TU, Petroni G. "Candidatus Fokinia solitaria", a Novel "Stand-Alone" Symbiotic Lineage of Midichloriaceae (Rickettsiales). PLoS One 2016; 11:e0145743. [PMID: 26731731 PMCID: PMC4701390 DOI: 10.1371/journal.pone.0145743] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 12/08/2015] [Indexed: 12/26/2022] Open
Abstract
Recently, the family Midichloriaceae has been described within the bacterial order Rickettsiales. It includes a variety of bacterial endosymbionts detected in different metazoan host species belonging to Placozoa, Cnidaria, Arthropoda and Vertebrata. Representatives of Midichloriaceae are also considered possible etiological agents of certain animal diseases. Midichloriaceae have been found also in protists like ciliates and amoebae. The present work describes a new bacterial endosymbiont, "Candidatus Fokinia solitaria", retrieved from three different strains of a novel Paramecium species isolated from a wastewater treatment plant in Rio de Janeiro (Brazil). Symbionts were characterized through the full-cycle rRNA approach: SSU rRNA gene sequencing and fluorescence in situ hybridization (FISH) with three species-specific oligonucleotide probes. In electron micrographs, the tiny rod-shaped endosymbionts (1.2 x 0.25-0.35 μm in size) were not surrounded by a symbiontophorous vacuole and were located in the peripheral host cytoplasm, stratified in the host cortex in between the trichocysts or just below them. Frequently, they occurred inside autolysosomes. Phylogenetic analyses of Midichloriaceae apparently show different evolutionary pathways within the family. Some genera, such as "Ca. Midichloria" and "Ca. Lariskella", have been retrieved frequently and independently in different hosts and environmental surveys. On the contrary, others, such as Lyticum, "Ca. Anadelfobacter", "Ca. Defluviella" and the presently described "Ca. Fokinia solitaria", have been found only occasionally and associated to specific host species. These last are the only representatives in their own branches thus far. Present data do not allow to infer whether these genera, which we named "stand-alone lineages", are an indication of poorly sampled organisms, thus underrepresented in GenBank, or represent fast evolving, highly adapted evolutionary lineages.
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Affiliation(s)
- Franziska Szokoli
- Institut für Hydrobiologie, Technische Universität Dresden, Dresden, Germany
- Dipartimento di Biologia, Università di Pisa, Pisa, Italy
| | - Elena Sabaneyeva
- Department of Cytology and Histology, St. Petersburg State University, St. Petersburg, Russia
| | | | - Sascha Krenek
- Institut für Hydrobiologie, Technische Universität Dresden, Dresden, Germany
| | - Martina Schrallhammer
- Mikrobiologie, Biologisches Institut II, Albert-Ludwigs Universität Freiburg, Freiburg, Germany
| | - Carlos A. G. Soares
- Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Thomas U. Berendonk
- Institut für Hydrobiologie, Technische Universität Dresden, Dresden, Germany
| | - Giulio Petroni
- Dipartimento di Biologia, Università di Pisa, Pisa, Italy
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15
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Filker S, Kaiser M, Rosselló-Móra R, Dunthorn M, Lax G, Stoeck T. “Candidatus Haloectosymbiotes riaformosensis” (Halobacteriaceae), an archaeal ectosymbiont of the hypersaline ciliate Platynematum salinarum. Syst Appl Microbiol 2014; 37:244-51. [DOI: 10.1016/j.syapm.2014.01.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 01/14/2014] [Accepted: 01/16/2014] [Indexed: 11/27/2022]
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16
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Schulz F, Lagkouvardos I, Wascher F, Aistleitner K, Kostanjšek R, Horn M. Life in an unusual intracellular niche: a bacterial symbiont infecting the nucleus of amoebae. ISME JOURNAL 2014; 8:1634-44. [PMID: 24500618 PMCID: PMC4817620 DOI: 10.1038/ismej.2014.5] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 12/13/2014] [Accepted: 01/01/2014] [Indexed: 11/09/2022]
Abstract
Amoebae serve as hosts for various intracellular bacteria, including human pathogens. These microbes are able to overcome amoebal defense mechanisms and successfully establish a niche for replication, which is usually the cytoplasm. Here, we report on the discovery of a bacterial symbiont that is located inside the nucleus of its Hartmannella sp. host. This symbiont, tentatively named 'Candidatus Nucleicultrix amoebiphila', is only moderately related to known bacteria (∼90% 16S and 23S rRNA sequence similarity) and member of a novel clade of protist symbionts affiliated with the Rickettsiales and Rhodospirillales. Screening of 16S rRNA amplicon data sets revealed a broad distribution of these bacteria in freshwater and soil habitats. 'Candidatus Nucleicultrix amoebiphila' traffics within 6 h post infection to the host nucleus. Maximum infection levels are reached after 96-120 h, at which time point the nucleus is pronouncedly enlarged and filled with bacteria. Transmission of the symbionts occurs vertically upon host cell division but may also occur horizontally through host cell lysis. Although we observed no impact on the fitness of the original Hartmannella sp. host, the bacteria are rather lytic for Acanthamoeba castellanii. Intranuclear symbiosis is an exceptional phenomenon, and amoebae represent an ideal model system to further investigate evolution and underlying molecular mechanisms of these unique microbial associations.
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Affiliation(s)
- Frederik Schulz
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, Austria
| | - Ilias Lagkouvardos
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, Austria
| | - Florian Wascher
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, Austria
| | - Karin Aistleitner
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, Austria
| | - Rok Kostanjšek
- Department of Biology, University of Ljubljana, Ljubljana, Slovenia
| | - Matthias Horn
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, Austria
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17
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Flagellar movement in two bacteria of the family rickettsiaceae: a re-evaluation of motility in an evolutionary perspective. PLoS One 2014; 9:e87718. [PMID: 24505307 PMCID: PMC3914857 DOI: 10.1371/journal.pone.0087718] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 01/02/2014] [Indexed: 01/22/2023] Open
Abstract
Bacteria of the family Rickettsiaceae have always been largely studied not only for their importance in the medical field, but also as model systems in evolutionary biology. In fact, they share a recent common ancestor with mitochondria. The most studied species, belonging to genera Rickettsia and Orientia, are hosted by terrestrial arthropods and include many human pathogens. Nevertheless, recent findings show that a large part of Rickettsiaceae biodiversity actually resides outside the group of well-known pathogenic bacteria. Collecting data on these recently described non-conventional members of the family is crucial in order to gain information on ancestral features of the whole group. Although bacteria of the family Rickettsiaceae, and of the whole order Rickettsiales, are formally described as non-flagellated prokaryotes, some recent findings renewed the debate about this feature. In this paper we report the first finding of members of the family displaying numerous flagella and active movement inside their host cells. These two new taxa are hosted in aquatic environments by protist ciliates and are described here by means of ultrastructural and molecular characterization. Data here reported suggest that the ancestor of Rickettsiales displayed flagellar movement and re-evaluate the hypothesis that motility played a key-role in the origin of mitochondria. Moreover, our study highlights that the aquatic environment represents a well exploited habitat for bacteria of the family Rickettsiaceae. Our results encourage a deep re-consideration of ecological and morphological traits of the family and of the whole order.
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18
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Boscaro V, Schrallhammer M, Benken KA, Krenek S, Szokoli F, Berendonk TU, Schweikert M, Verni F, Sabaneyeva EV, Petroni G. Rediscovering the genus Lyticum, multiflagellated symbionts of the order Rickettsiales. Sci Rep 2013; 3:3305. [PMID: 24264310 PMCID: PMC3837311 DOI: 10.1038/srep03305] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 10/21/2013] [Indexed: 11/09/2022] Open
Abstract
Among the bacterial symbionts harbored by the model organism Paramecium, many still lack a recent investigation that includes a molecular characterization. The genus Lyticum consists of two species of large-sized bacteria displaying numerous flagella, despite their inability to move inside their hosts' cytoplasm. We present a multidisciplinary redescription of both species, using the deposited type strains as well as newly collected material. On the basis of 16S rRNA gene sequences, we assigned Lyticum to the order Rickettsiales, that is intensely studied because of its pathogenic representatives and its position as the extant group most closely related to the mitochondrial ancestor. We provide conclusive proofs that at least some Rickettsiales possess actual flagella, a feature that has been recently predicted from genomic data but never confirmed. We give support to the hypothesis that the mitochondrial ancestor could have been flagellated, and provide the basis for further studies on these ciliate endosymbionts.
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19
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Gong J, Qing Y, Guo X, Warren A. "Candidatus Sonnebornia yantaiensis", a member of candidate division OD1, as intracellular bacteria of the ciliated protist Paramecium bursaria (Ciliophora, Oligohymenophorea). Syst Appl Microbiol 2013; 37:35-41. [PMID: 24231291 DOI: 10.1016/j.syapm.2013.08.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Revised: 08/29/2013] [Accepted: 08/30/2013] [Indexed: 10/26/2022]
Abstract
An intracellular bacterium was discovered in an isolate of Paramecium bursaria from a freshwater pond in Yantai, China. The bacteria were abundant and exclusively found in the cytoplasm of the host which, along with the green alga Chlorella, formed a three-partner consortium that could survive in pure water for at least one week. Cloning, sequencing and phylogenetic analysis of the bacterial 16S rRNA gene showed that the bacterium belonged to the uncultured candidate division OD1, which usually forms part of the rare biosphere. Transmission electron microscopy and fluorescence in situ hybridization (FISH) with specific probes showed that the bacteria were usually located close to the perialgal membranes of endosymbiotic Chlorella cells, and occasionally irregularly distributed throughout the host cytoplasm. The name "Candidatus Sonnebornia yantaiensis" gen. nov., sp. nov. is proposed for the new bacterium. A strongly supported monophyletic subclade, OD1-p, which included the new species, was recognized and this study highlights that protists can be important hosts for rare bacterial taxa.
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Affiliation(s)
- Jun Gong
- Microbial Ecology Group, Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China; College of Life Sciences, South China Normal University, Guangzhou 510631, China.
| | - Yao Qing
- Microbial Ecology Group, Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China; College of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Xiaohong Guo
- Microbial Ecology Group, Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
| | - Alan Warren
- Department of Life Sciences, Natural History Museum, London SW7 5BD, United Kingdom
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20
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Rautian MS, Wackerow-Kouzova ND. Phylogenetic placement of two previously described intranuclear bacteria from the ciliate Paramecium bursaria (Protozoa, Ciliophora): 'Holospora acuminata' and 'Holospora curviuscula'. Int J Syst Evol Microbiol 2013; 63:1930-1933. [PMID: 23504970 DOI: 10.1099/ijs.0.046631-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
'Holospora acuminata' infects micronuclei of Paramecium bursaria (Protozoa, Ciliophora), whereas 'Holospora curviuscula' infects the macronucleus in other clones of the same host species. Because these micro-organisms have not been cultivated, their description has been based only on some morphological properties and host and nuclear specificities. One16S rRNA gene sequence of 'H. curviuscula' is present in databases. The systematic position of the representative strain of 'H. curviuscula', strain MC-3, was determined in this study. Moreover, for the first time, two strains of 'H. acuminata', KBN10-1 and AC61-10, were investigated. Phylogenetic analysis indicated that all three strains belonged to the genus Holospora, family Holosporaceae, order Rickettsiales within the Alphaproteobacteria.
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Affiliation(s)
- Maria S Rautian
- Department of Genetics and Selection, Faculty of Biology and Soil Science, Saint Petersburg State University, 7-9 Universitetskaya nab., St. Petersburg 199034, Russia
| | - Natalia D Wackerow-Kouzova
- Department of Genetics and Selection, Faculty of Biology and Soil Science, Saint Petersburg State University, 7-9 Universitetskaya nab., St. Petersburg 199034, Russia
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21
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Boscaro V, Petroni G, Ristori A, Verni F, Vannini C. "Candidatus Defluviella procrastinata" and "Candidatus Cyrtobacter zanobii", two novel ciliate endosymbionts belonging to the "Midichloria clade". MICROBIAL ECOLOGY 2013; 65:302-310. [PMID: 23296446 DOI: 10.1007/s00248-012-0170-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 12/17/2012] [Indexed: 06/01/2023]
Abstract
The "Midichloria clade" is a recently discovered but well-established evolutionary lineage clustering inside the order Rickettsiales (Alphaproteobacteria). Not much is known about the biology of these organisms. The best characterized ones are endocellular symbionts of very different eukaryotic hosts, ranging from arthropods to protists. "Candidatus Midichloria mitochondrii", the most studied organism of the group, is an interesting object of study because of its unique capability to infect metazoans' mitochondria and the presence of flagellar genes in its genome. With this work, we aim at increasing the knowledge on the biodiversity and phylogeny of the "Midichloria group". We characterized according to the "full cycle rRNA approach" two novel endosymbionts of ciliated protozoa, i.e. Paramecium nephridiatum and Euplotes aediculatus. According to the nomenclatural rules for uncultivated prokaryotes, we established the novel taxa "Candidatus Defluviella procrastinata" and "Candidatus Cyrtobacter zanobii" for the two bacterial symbionts. Our phylogenetic analysis based on 16S rRNA gene sequences confirms that the evolutionary histories of "Midichloria clade" representatives and of their hosts are very different. This suggests that the symbiotic processes arose many times independently, perhaps through ways of transmission still not described in Rickettsiales.
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Affiliation(s)
- Vittorio Boscaro
- Biology Department, Protistology-Zoology Unit, University of Pisa, Pisa, Italy
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22
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Boscaro V, Fokin SI, Schrallhammer M, Schweikert M, Petroni G. Revised systematics of Holospora-like bacteria and characterization of "Candidatus Gortzia infectiva", a novel macronuclear symbiont of Paramecium jenningsi. MICROBIAL ECOLOGY 2013; 65:255-267. [PMID: 22940732 DOI: 10.1007/s00248-012-0110-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 08/07/2012] [Indexed: 06/01/2023]
Abstract
The genus Holospora (Rickettsiales) includes highly infectious nuclear symbionts of the ciliate Paramecium with unique morphology and life cycle. To date, nine species have been described, but a molecular characterization is lacking for most of them. In this study, we have characterized a novel Holospora-like bacterium (HLB) living in the macronuclei of a Paramecium jenningsi population. This bacterium was morphologically and ultrastructurally investigated in detail, and its life cycle and infection capabilities were described. We also obtained its 16S rRNA gene sequence and developed a specific probe for fluorescence in situ hybridization experiments. A new taxon, "Candidatus Gortzia infectiva", was established for this HLB according to its unique characteristics and the relatively low DNA sequence similarities shared with other bacteria. The phylogeny of the order Rickettsiales based on 16S rRNA gene sequences has been inferred, adding to the available data the sequence of the novel bacterium and those of two Holospora species (Holospora obtusa and Holospora undulata) characterized for the purpose. Our phylogenetic analysis provided molecular support for the monophyly of HLBs and showed a possible pattern of evolution for some of their features. We suggested to classify inside the family Holosporaceae only HLBs, excluding other more distantly related and phenotypically different Paramecium endosymbionts.
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Affiliation(s)
- Vittorio Boscaro
- Biology Department, Protistology-Zoology Unit, University of Pisa, Via A. Volta 4, 56126 Pisa, Italy
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23
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Boscaro V, Vannini C, Fokin SI, Verni F, Petroni G. Characterization of “Candidatus Nebulobacter yamunensis” from the cytoplasm of Euplotes aediculatus (Ciliophora, Spirotrichea) and emended description of the family Francisellaceae. Syst Appl Microbiol 2012; 35:432-40. [DOI: 10.1016/j.syapm.2012.07.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 07/02/2012] [Accepted: 07/26/2012] [Indexed: 12/31/2022]
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24
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Fokin SI. Frequency and biodiversity of symbionts in representatives of the main classes of Ciliophora. Eur J Protistol 2012; 48:138-48. [DOI: 10.1016/j.ejop.2011.12.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 12/15/2011] [Accepted: 12/16/2011] [Indexed: 10/28/2022]
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25
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Vakkerov-Kouzova ND, Rautian MS. Obtaining and characterization of “Holospora curviuscula” and Holospora obtusa, bacterial symbionts of the macronuclei of Paramecium bursaria and Paramecium caudatum. Microbiology (Reading) 2011. [DOI: 10.1134/s0026261711050171] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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26
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"Candidatus anadelfobacter veles" and "Candidatus cyrtobacter comes," two new rickettsiales species hosted by the protist ciliate Euplotes harpa (Ciliophora, Spirotrichea). Appl Environ Microbiol 2010; 76:4047-54. [PMID: 20435776 DOI: 10.1128/aem.03105-09] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The order Rickettsiales (Alphaproteobacteria) is a well-known group containing obligate endocellular prokaryotes. The order encompasses three families (Rickettsiaceae, Anaplasmataceae, and Holosporaceae) and a fourth, family-level cluster, which includes only one candidate species, "Candidatus Midichloria mitochondrii," as well as several unnamed bacterial symbionts. The broad host range exhibited by the members of the "Candidatus Midichloria" clade suggests their eventual relevance for a better understanding of the evolution of symbiosis and host specificity of Rickettsiales. In this paper, two new bacteria belonging to the "Candidatus Midichloria" clade, hosted by two different strains of the ciliate protist Euplotes harpa, are described on the basis of ultrastructural observations, comparative 16S rRNA gene sequence analysis, and an estimation of the percentage of infection. Ultrastructure of these bacteria shows some unusual features: one has an electron-dense cytoplasm, and the other one lacks a symbiosomal membrane. The latter was up to now considered an exclusive feature of bacteria belonging to the family Rickettsiaceae. 16S rRNA gene phylogenetic analysis unambiguously places the new bacteria in the "Candidatus Midichloria" clade, although their phylogenetic relationships with other members of the clade are not clearly resolved. This is the first report of a ciliate-borne bacterium belonging to the "Candidatus Midichloria" clade. On the basis of the data obtained, the two bacteria are proposed as two new candidate genera and species, "Candidatus Anadelfobacter veles" and "Candidatus Cyrtobacter comes."
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