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Gile GH. Protist symbionts of termites: diversity, distribution, and coevolution. Biol Rev Camb Philos Soc 2024; 99:622-652. [PMID: 38105542 DOI: 10.1111/brv.13038] [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: 08/07/2023] [Revised: 11/28/2023] [Accepted: 11/30/2023] [Indexed: 12/19/2023]
Abstract
The symbiosis between termites and their hindgut protists is mutually obligate and vertically inherited. It was established by the late Jurassic in the cockroach ancestors of termites as they transitioned to wood feeding. Since then, protist symbionts have been transmitted from host generation to host generation by proctodeal trophallaxis (anal feeding). The protists belong to multiple lineages within the eukaryotic superphylum Metamonada. Most of these lineages have evolved large cells with complex morphology, unlike the non-termite-associated Metamonada. The species richness and taxonomic composition of symbiotic protist communities varies widely across termite lineages, especially within the deep-branching clade Teletisoptera. In general, closely related termites tend to harbour closely related protists, and deep-branching termites tend to harbour deep-branching protists, reflecting their broad-scale co-diversification. A closer view, however, reveals a complex distribution of protist lineages across hosts. Some protist taxa are common, some are rare, some are widespread, and some are restricted to a single host family or genus. Some protist taxa can be found in only a few, distantly related, host species. Thus, the long history of co-diversification in this symbiosis has been complicated by lineage-specific loss of symbionts, transfer of symbionts from one host lineage to another, and by independent diversification of the symbionts relative to their hosts. This review aims to introduce the biology of this important symbiosis and serve as a gateway to the diversity and systematics literature for both termites and protists. A searchable database with all termite-protist occurrence records and taxonomic references is provided as a supplementary file to encourage and facilitate new research in this field.
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Affiliation(s)
- Gillian H Gile
- School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA
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Characterization of new cristamonad species from kalotermitid termites including a novel genus, Runanympha. Sci Rep 2021; 11:7270. [PMID: 33790354 PMCID: PMC8012604 DOI: 10.1038/s41598-021-86645-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 03/16/2021] [Indexed: 12/04/2022] Open
Abstract
Cristamonadea is a large class of parabasalian protists that reside in the hindguts of wood-feeding insects, where they play an essential role in the digestion of lignocellulose. This group of symbionts boasts an impressive array of complex morphological characteristics, many of which have evolved multiple times independently. However, their diversity is understudied and molecular data remain scarce. Here we describe seven new species of cristamonad symbionts from Comatermes, Calcaritermes, and Rugitermes termites from Peru and Ecuador. To classify these new species, we examined cells by light and scanning electron microscopy, sequenced the symbiont small subunit ribosomal RNA (rRNA) genes, and carried out barcoding of the mitochondrial large subunit rRNA gene of the hosts to confirm host identification. Based on these data, five of the symbionts characterized here represent new species within described genera: Devescovina sapara n. sp., Devescovina aymara n. sp., Macrotrichomonas ashaninka n. sp., Macrotrichomonas secoya n. sp., and Macrotrichomonas yanesha n. sp. Additionally, two symbionts with overall morphological characteristics similar to the poorly-studied and probably polyphyletic ‘joeniid’ Parabasalia are classified in a new genus Runanympha n. gen.: Runanympha illapa n. sp., and Runanympha pacha n. sp.
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Schulz F, Horn M. Intranuclear bacteria: inside the cellular control center of eukaryotes. Trends Cell Biol 2015; 25:339-46. [PMID: 25680230 DOI: 10.1016/j.tcb.2015.01.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 01/14/2015] [Accepted: 01/15/2015] [Indexed: 12/17/2022]
Abstract
Intracellular bacteria including major pathogens live in the cytoplasm or in cytoplasmic vacuoles within their host cell. However, some can invade more unusual intracellular niches such as the eukaryotic nucleus. Phylogenetically diverse intranuclear bacteria have been discovered in various protist, arthropod, marine invertebrate, and mammalian hosts. Although targeting the same cellular compartment, they have apparently developed fundamentally-different infection strategies. The nucleus provides a rich pool of nutrients and protection against host cytoplasmic defense mechanisms; intranuclear bacteria can directly manipulate the host by interfering with nuclear processes. The impact on their host cells ranges from stable associations with a neutral or beneficial effect on host fitness to rapid host lysis. The analysis of the intranuclear lifestyle will extend our current framework for understanding host-pathogen interactions.
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Affiliation(s)
- Frederik Schulz
- Department of Microbiology and Ecosystem Science, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
| | - Matthias Horn
- Department of Microbiology and Ecosystem Science, University of Vienna, Althanstraße 14, 1090 Vienna, Austria.
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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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Intranuclear verrucomicrobial symbionts and evidence of lateral gene transfer to the host protist in the termite gut. ISME JOURNAL 2013; 8:1008-19. [PMID: 24335826 DOI: 10.1038/ismej.2013.222] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 10/23/2013] [Accepted: 11/07/2013] [Indexed: 11/09/2022]
Abstract
In 1944, Harold Kirby described microorganisms living within nuclei of the protists Trichonympha in guts of termites; however, their taxonomic assignment remains to be accomplished. Here, we identified intranuclear symbionts of Trichonympha agilis in the gut of the termite Reticulitermes speratus. We isolated single nuclei of T. agilis, performed whole-genome amplification, and obtained bacterial 16S rRNA genes by PCR. Unexpectedly, however, all of the analyzed clones were from pseudogenes of 16S rRNA with large deletions and numerous sequence variations even within a single-nucleus sample. Authentic 16S rRNA gene sequences were finally recovered by digesting the nuclear DNA; these pseudogenes were present on the host Trichonympha genome. The authentic sequences represented two distinct bacterial species belonging to the phylum Verrucomicrobia, and the pseudogenes have originated from each of the two species. Fluorescence in situ hybridization confirmed that both species are specifically localized, and occasionally co-localized, within nuclei of T. agilis. Transmission electron microscopy revealed that they are distorted cocci with characteristic electron-dense and lucent regions, which resemble the intranuclear symbionts illustrated by Kirby. For these symbionts, we propose a novel genus and species, 'Candidatus Nucleococcus trichonymphae' and 'Candidatus Nucleococcus kirbyi'. These formed a termite-specific cluster with database sequences, other members of which were also detected within nuclei of various gut protists, including both parabasalids and oxymonads. We suggest that this group is widely distributed as intranuclear symbionts of diverse protists in termite guts and that they might have affected the evolution of the host genome through lateral gene transfer.
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Critical Taxonomic Revision of Parabasalids with Description of one New Genus and three New Species. Protist 2010; 161:400-33. [DOI: 10.1016/j.protis.2009.11.005] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Accepted: 11/21/2009] [Indexed: 11/17/2022]
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Desai MS, Strassert JFH, Meuser K, Hertel H, Ikeda-Ohtsubo W, Radek R, Brune A. Strict cospeciation of devescovinid flagellates and Bacteroidales ectosymbionts in the gut of dry-wood termites (Kalotermitidae). Environ Microbiol 2009; 12:2120-32. [PMID: 21966907 DOI: 10.1111/j.1462-2920.2009.02080.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The surface of many termite gut flagellates is colonized with a dense layer of bacteria, yet little is known about the evolutionary relationships of such ectosymbionts and their hosts. Here we investigated the molecular phylogenies of devescovinid flagellates (Devescovina spp.) and their symbionts from a wide range of dry-wood termites (Kalotermitidae). From species-pure flagellate suspensions isolated with micropipettes, we obtained SSU rRNA gene sequences of symbionts and host. Phylogenetic analysis showed that the Devescovina spp. present in many species of Kalotermitidae form a monophyletic group, which includes also the unique devescovinid flagellate Caduceia versatilis. All members of this group were consistently associated with a distinct lineage of Bacteroidales, whose location on the cell surface was confirmed by fluorescence in situ hybridization. The well-supported congruence of the phylogenies of devescovinids and their ectosymbionts documents a strict cospeciation. In contrast, the endosymbionts of the same flagellates ('Endomicrobia') were clearly polyphyletic and must have been acquired independently by horizontal transfer from other flagellate lineages. Also the Bacteroidales ectosymbionts of Oxymonas flagellates present in several Kalotermitidae belonged to several distantly related lines of descent, underscoring the general perception that the evolutionary history of flagellate-bacteria symbioses in the termite gut is complex.
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Affiliation(s)
- Mahesh S Desai
- Max Planck Institute for Terrestrial Microbiology, Department of Biogeochemistry, Karl-von-Frisch-Straße, 35043 Marburg, Germany
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Noda S, Hongoh Y, Sato T, Ohkuma M. Complex coevolutionary history of symbiotic Bacteroidales bacteria of various protists in the gut of termites. BMC Evol Biol 2009; 9:158. [PMID: 19586555 PMCID: PMC2717939 DOI: 10.1186/1471-2148-9-158] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Accepted: 07/09/2009] [Indexed: 12/03/2022] Open
Abstract
Background The microbial community in the gut of termites is responsible for the efficient decomposition of recalcitrant lignocellulose. Prominent features of this community are its complexity and the associations of prokaryotes with the cells of cellulolytic flagellated protists. Bacteria in the order Bacteroidales are involved in associations with a wide variety of gut protist species as either intracellular endosymbionts or surface-attached ectosymbionts. In particular, ectosymbionts exhibit distinct morphological patterns of the associations. Therefore, these Bacteroidales symbionts provide an opportunity to investigate not only the coevolutionary relationships with the host protists and their morphological evolution but also how symbiotic associations between prokaryotes and eukaryotes occur and evolve within a complex symbiotic community. Results Molecular phylogeny of 31 taxa of Bacteroidales symbionts from 17 protist genera in 10 families was examined based on 16S rRNA gene sequences. Their localization, morphology, and specificity were also examined by fluorescent in situ hybridizations. Although a monophyletic grouping of the ectosymbionts occurred in three related protist families, the symbionts of different protist genera were usually dispersed among several phylogenetic clusters unique to termite-gut bacteria. Similar morphologies of the associations occurred in multiple lineages of the symbionts. Nevertheless, the symbionts of congeneric protist species were closely related to one another, and in most cases, each host species harbored a unique Bacteroidales species. The endosymbionts were distantly related to the ectosymbionts examined so far. Conclusion The coevolutionary history of gut protists and their associated Bacteroidales symbionts is complex. We suggest multiple independent acquisitions of the Bacteroidales symbionts by different protist genera from a pool of diverse bacteria in the gut community. In this sense, the gut could serve as a reservoir of diverse bacteria for associations with the protist cells. The similar morphologies are considered a result of evolutionary convergence. Despite the complicated evolutionary history, the host-symbiont relationships are mutually specific, suggesting their cospeciations at the protist genus level with only occasional replacements.
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Affiliation(s)
- Satoko Noda
- Ecomolecular Biorecycling Science Research Team, RIKEN Advanced Science Institute, Wako, Saitama 351-0198, Japan.
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Noël C, Noda S, Mantini C, Dolan MF, Moriya S, Delgado-Viscogliosi P, Kudo T, Capron M, Pierce RJ, Ohkuma M, Viscogliosi E. Molecular phylogenetic position of the genera Stephanonympha and Caduceia (Parabasalia) inferred from nuclear small subunit rRNA gene sequences. J Eukaryot Microbiol 2007; 54:93-9. [PMID: 17300526 DOI: 10.1111/j.1550-7408.2006.00234.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nuclear small subunit (SSU) rRNA gene sequences were obtained by polymerase chain reaction from trichomonad symbionts of termites that belong to the Devescovinidae (Caduceia versatilis) and polymastigont Calonymphidae (Stephanonympha nelumbium). The unidentified SSU rRNA sequence Nk3, previously obtained from the termite Neotermes koshunensis, has also been shown to derive from a Stephanonympha sp. by in situ hybridization. These sequences were analysed in a broad phylogeny including nearly all identified parabasalid sequences available in the databases, and some as yet unidentified sequences likely deriving from the new order Cristamonadida (Devescovinidae, Calonymphidae, and hypermastigids Lophomonadida). A global phylogeny of parabasalids reveals a partial agreement between the clades identified in this work and the last classification of this phylum into four orders. However, this classification is still incongruent with our data and new taxonomic considerations are proposed. The analysis confirms the monophyly of the Cristamonadida and separates this order into two groups: the first unites nearly all the Devescovinidae including Caduceia and the Calonymphidae Coronympha and Metacoronympha, whereas the second group is composed of a few Devescovinidae, Lophomonadida, and Calonymphidae such as Stephanonympha. Caduceia is closely related to Devescovina, corroborating the marked morphological similarity between these two genera whereas Stephanonympha groups together with the Calonymphidae Snyderella and Calonympha. These data also confirm the polyphyly of the families Devescovinidae and Calonymphidae and support the arrangement of the axostyle-pelta complexes as a valuable character for taxonomic considerations within the Calonymphidae.
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Affiliation(s)
- Christophe Noël
- Inserm, U547, Institut Pasteur de Lille, 1 Rue du Professeur Calmette, BP 245, 59019 Lille cedex, France
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Hongoh Y, Sato T, Dolan MF, Noda S, Ui S, Kudo T, Ohkuma M. The motility symbiont of the termite gut flagellate Caduceia versatilis is a member of the "Synergistes" group. Appl Environ Microbiol 2007; 73:6270-6. [PMID: 17675420 PMCID: PMC2074993 DOI: 10.1128/aem.00750-07] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The flagellate Caduceia versatilis in the gut of the termite Cryptotermes cavifrons reportedly propels itself not by its own flagella but solely by the flagella of ectosymbiotic bacteria. Previous microscopic observations have revealed that the motility symbionts are flagellated rods partially embedded in the host cell surface and that, together with a fusiform type of ectosymbiotic bacteria without flagella, they cover almost the entire surface. To identify these ectosymbionts, we conducted 16S rRNA clone analyses of bacteria physically associated with the Caduceia cells. Two phylotypes were found to predominate in the clone library and were phylogenetically affiliated with the "Synergistes" phylum and the order Bacteroidales in the Bacteroidetes phylum. Probes specifically targeting 16S rRNAs of the respective phylotypes were designed, and fluorescence in situ hybridization (FISH) was performed. As a result, the "Synergistes" phylotype was identified as the motility symbiont; the Bacteroidales phylotype was the fusiform ectobiont. The "Synergistes" phylotype was a member of a cluster comprising exclusively uncultured clones from the guts of various termite species. Interestingly, four other phylotypes in this cluster, including the one sharing 95% sequence identity with the motility symbiont, were identified as nonectosymbiotic, or free-living, gut bacteria by FISH. We thus suggest that the motility ectosymbiont has evolved from a free-living gut bacterium within this termite-specific cluster. Based on these molecular and previous morphological data, we here propose a novel genus and species, "Candidatus Tammella caduceiae," for this unique motility ectosymbiont of Caducaia versatilis.
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Affiliation(s)
- Yuichi Hongoh
- Environmental Molecular Biology Laboratory, RIKEN, Saitama 351-0198, Japan.
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Margulis L, Chapman M, Guerrero R, Hall J. The last eukaryotic common ancestor (LECA): acquisition of cytoskeletal motility from aerotolerant spirochetes in the Proterozoic Eon. Proc Natl Acad Sci U S A 2006; 103:13080-5. [PMID: 16938841 PMCID: PMC1559756 DOI: 10.1073/pnas.0604985103] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We develop a symbiogenetic concept of the origin of eukaryotic intracellular motility systems from anaerobic but aerotolerant spirochetes in sulfide-rich environments. The last eukaryotic common ancestors (LECAs) have extant archaeprotist descendants: motile nucleated cells with Embden-Meyerhof glycolysis and substrate-level phosphorylation that lack the alpha-proteobacterial symbiont that became the mitochondrion. Swimming and regulated O(2)-tolerance via sulfide oxidation already had been acquired by sulfidogenic wall-less archaebacteria (thermoplasmas) after aerotolerant cytoplasmic-tubule-containing spirochetes (eubacteria) attached to them. Increasing stability of sulfide-oxidizing/sulfur-reducing consortia analogous to extant sulfur syntrophies (Thiodendron) led to fusion. The eubacteria-archaebacteria symbiosis became permanent as the nucleus evolved by prokaryotic recombination with membrane hypertrophy, analogous to Gemmata obscuriglobus and other delta-proteobacteria with membrane-bounded nucleoids. Histone-coated DNA, protein-synthetic RNAs, amino-acylating, and other enzymes were contributed by the sulfidogen whereas most intracellular motility derives from the spirochete. From this redox syntrophy in anoxic and microoxic Proterozoic habitats LECA evolved. The nucleus originated by recombination of eu- and archaebacterial DNA that remained attached to eubacterial motility structures and became the microtubular cytoskeleton, including the mitotic apparatus. Direct LECA descendants include free-living archaeprotists in anoxic environments: archamoebae, metamonads, parabasalids, and some mammalian symbionts with mitosomes. LECA later acquired the fully aerobic Krebs cycle-oxidative phosphorylation-mitochondrial metabolism by integration of the protomitochondrion, a third alpha-proteobacterial symbiont from which the ancestors to most protoctists, all fungi, plants, and animals evolved. Secondarily anaerobic eukaryotes descended from LECA after integration of this oxygen-respiring eubacterium. Explanatory power and experimental predictions for molecular biology of the LECA concept are stated.
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Affiliation(s)
- Lynn Margulis
- *Department of Geosciences, University of Massachusetts, Amherst, MA 01003
| | - Michael Chapman
- Department of Biology, Holy Cross College, Worcester, MA 01610
| | - Ricardo Guerrero
- Department of Microbiology, University of Barcelona, 08028 Barcelona, Spain; and
| | - John Hall
- *Department of Geosciences, University of Massachusetts, Amherst, MA 01003
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Brune A, Stingl U. Prokaryotic symbionts of termite gut flagellates: phylogenetic and metabolic implications of a tripartite symbiosis. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2006; 41:39-60. [PMID: 16623388 DOI: 10.1007/3-540-28221-1_3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Affiliation(s)
- Andreas Brune
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
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Dolan MF, Wier AM, Melnitsky H, Whiteside JH, Margulis L. Cysts and symbionts of Staurojoenina assimilis Kirby from Neotermes. Eur J Protistol 2004. [DOI: 10.1016/j.ejop.2004.01.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Stingl U, Maass A, Radek R, Brune A. Symbionts of the gut flagellate Staurojoenina sp. from Neotermes cubanus represent a novel, termite-associated lineage of Bacteroidales: description of ‘Candidatus Vestibaculum illigatum’. Microbiology (Reading) 2004; 150:2229-2235. [PMID: 15256565 DOI: 10.1099/mic.0.27135-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The symbioses between cellulose-degrading flagellates and bacteria are one of the most fascinating phenomena in the complex micro-ecosystem found in the hindgut of lower termites. However, little is known about the identity of the symbionts. One example is the epibiotic bacteria colonizing the surface of hypermastigote protists of the genusStaurojoenina. By using scanning electron microscopy, it was shown that the whole surface ofStaurojoeninasp. from the termiteNeotermes cubanusis densely covered with long rod-shaped bacteria of uniform size and morphology. PCR amplification of 16S rRNA genes from isolated protozoa and subsequent cloning yielded a uniform collection of clones with virtually identical sequences. Phylogenetic analysis placed them as a new lineage among theBacteroidales, only distantly related to other uncultivated bacteria in the hindgut of other termites, including an epibiont of the flagellateMixotricha paradoxa. The closest cultivated relative wasTannerella forsythensis(<85 % sequence identity). Fluorescencein situhybridization with a newly designed clone-specific oligonucleotide probe confirmed that these sequences belong to the rod-shaped epibionts ofStaurojoeninasp. Transmission electron microscopy confirmed the presence of a Gram-negative cell wall and revealed special attachment sites for the symbionts on the cell envelope of the flagellate host. Based on the isolated phylogenetic position and the specific association with the surface ofStaurojoeninasp., we propose to classify this new taxon ofBacteroidalesunder the provisional name ‘CandidatusVestibaculum illigatum’.
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Affiliation(s)
- Ulrich Stingl
- LS Mikrobielle Ökologie, Fachbereich Biologie, Universität Konstanz, 78457 Konstanz, Germany
| | - Annelie Maass
- Institut für Biologie/Zoologie, AG Protozoologie, Freie Universität Berlin, Königin-Luise-Str. 1-3, 14195 Berlin, Germany
| | - Renate Radek
- Institut für Biologie/Zoologie, AG Protozoologie, Freie Universität Berlin, Königin-Luise-Str. 1-3, 14195 Berlin, Germany
| | - Andreas Brune
- Max-Planck-Institut für terrestrische Mikrobiologie, Karl-von-Frisch-Strasse, 35043 Marburg, Germany
- LS Mikrobielle Ökologie, Fachbereich Biologie, Universität Konstanz, 78457 Konstanz, Germany
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Margulis L, Dolan MF, Guerrero R. The chimeric eukaryote: origin of the nucleus from the karyomastigont in amitochondriate protists. Proc Natl Acad Sci U S A 2000; 97:6954-9. [PMID: 10860956 PMCID: PMC34369 DOI: 10.1073/pnas.97.13.6954] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We present a testable model for the origin of the nucleus, the membrane-bounded organelle that defines eukaryotes. A chimeric cell evolved via symbiogenesis by syntrophic merger between an archaebacterium and a eubacterium. The archaebacterium, a thermoacidophil resembling extant Thermoplasma, generated hydrogen sulfide to protect the eubacterium, a heterotrophic swimmer comparable to Spirochaeta or Hollandina that oxidized sulfide to sulfur. Selection pressure for speed swimming and oxygen avoidance led to an ancient analogue of the extant cosmopolitan bacterial consortium "Thiodendron latens." By eubacterial-archaebacterial genetic integration, the chimera, an amitochondriate heterotroph, evolved. This "earliest branching protist" that formed by permanent DNA recombination generated the nucleus as a component of the karyomastigont, an intracellular complex that assured genetic continuity of the former symbionts. The karyomastigont organellar system, common in extant amitochondriate protists as well as in presumed mitochondriate ancestors, minimally consists of a single nucleus, a single kinetosome and their protein connector. As predecessor of standard mitosis, the karyomastigont preceded free (unattached) nuclei. The nucleus evolved in karyomastigont ancestors by detachment at least five times (archamoebae, calonymphids, chlorophyte green algae, ciliates, foraminifera). This specific model of syntrophic chimeric fusion can be proved by sequence comparison of functional domains of motility proteins isolated from candidate taxa.
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Affiliation(s)
- L Margulis
- Department of Geosciences, Organismic and Evolutionary Biology Graduate Program, University of Massachusetts, Amherst, MA 01003, USA
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Brugerolle G. A microscopical investigation of the genus Foaina, a parabasalid protist symbiotic in termites and phylogenetic considerations. Eur J Protistol 2000. [DOI: 10.1016/s0932-4739(00)80018-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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