1
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Cadena LR, Edgcomb V, Lukeš J. Gazing into the abyss: A glimpse into the diversity, distribution, and behaviour of heterotrophic protists from the deep-sea floor. Environ Microbiol 2024; 26:e16598. [PMID: 38444221 DOI: 10.1111/1462-2920.16598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 02/08/2024] [Indexed: 03/07/2024]
Abstract
The benthic biome of the deep-sea floor, one of the largest biomes on Earth, is dominated by diverse and highly productive heterotrophic protists, second only to prokaryotes in terms of biomass. Recent evidence suggests that these protists play a significant role in ocean biogeochemistry, representing an untapped source of knowledge. DNA metabarcoding and environmental sample sequencing have revealed that deep-sea abyssal protists exhibit high levels of specificity and diversity across local regions. This review aims to provide a comprehensive summary of the known heterotrophic protists from the deep-sea floor, their geographic distribution, and their interactions in terms of parasitism and predation. We offer an overview of the most abundant groups and discuss their potential ecological roles. We argue that the exploration of the biodiversity and species-specific features of these protists should be integrated into broader deep-sea research and assessments of how benthic biomes may respond to future environmental changes.
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Affiliation(s)
- Lawrence Rudy Cadena
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Virginia Edgcomb
- Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
- Faculty of Sciences, University of South Bohemia, České Budějovice, Czech Republic
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2
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Lax G, Keeling PJ. Molecular phylogenetics of sessile Dolium sedentarium, a petalomonad euglenid. J Eukaryot Microbiol 2023; 70:e12991. [PMID: 37424051 DOI: 10.1111/jeu.12991] [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: 04/05/2023] [Revised: 06/19/2023] [Accepted: 06/19/2023] [Indexed: 07/11/2023]
Abstract
The euglenids are a species-rich group of flagellates with varying modes of nutrition that can be found in diverse habitats. Phagotrophic members of this group gave rise to phototrophs and hold the key to understanding the evolution of euglenids as a whole, including the evolution of complex morphological characters like the euglenid pellicle. Yet to understand the evolution of these characters, a comprehensive sampling of molecular data is needed to correlate morphological and molecular data, and to estimate a basic phylogenetic backbone of the group. While the availability of SSU rDNA and, more recently, multigene data from phagotrophic euglenids has improved, several "orphan" taxa remain without any molecular data whatsoever. Dolium sedentarium is one such taxon: It is a rarely-observed phagotrophic euglenid that inhabits tropical benthic environments and is one of few known sessile euglenids. Based on morphological characters, it has been thought of as part of the earliest branch of euglenids, the Petalomonadida. We report the first molecular sequencing data for Dolium using single-cell transcriptomics, adding another small piece in the puzzle of euglenid evolution. Both SSU rDNA and multigene phylogenies confirm it as a solitary branch within Petalomonadida.
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Affiliation(s)
- Gordon Lax
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Patrick J Keeling
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
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3
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Lax G, Cho A, Keeling PJ. Phylogenomics of novel ploeotid taxa contribute to the backbone of the euglenid tree. J Eukaryot Microbiol 2023; 70:e12973. [PMID: 36912454 DOI: 10.1111/jeu.12973] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/02/2023] [Accepted: 03/04/2023] [Indexed: 03/14/2023]
Abstract
Euglenids are a diverse group of flagellates that inhabit most environments and exhibit many different nutritional modes. The most prominent euglenids are phototrophs, but phagotrophs constitute the majority of phylogenetic diversity of euglenids. They are pivotal to our understanding of euglenid evolution, yet we are only starting to understand relationships amongst phagotrophs, with the backbone of the tree being most elusive. Ploeotids make up most of this backbone diversity-yet despite their morphological similarities, SSU rDNA analyses and multigene analyses show that they are non-monophyletic. As more ploeotid diversity is sampled, known taxa have coalesced into some subgroups (e.g. Alistosa), but the relationships amongst these are not always supported and some taxa remain unsampled for multigene phylogenetics. Here, we used light microscopy and single-cell transcriptomics to characterize five ploeotid euglenids and place them into a multigene phylogenetic framework. Our analyses place Decastava in Alistosa; while Hemiolia branches with Liburna, establishing the novel clade Karavia. We describe Hemiolia limna, a freshwater-dwelling species in an otherwise marine clade. Intriguingly, two undescribed ploeotids are found to occupy pivotal positions in the tree: Chelandium granulatum nov. gen. nov. sp. branches as sister to Olkasia, and Gaulosia striata nov. gen. nov. sp. remains an orphan taxon.
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Affiliation(s)
- Gordon Lax
- Department of Botany, University of British Columbia, Vancouver, V6T 1Z4, British Columbia, Canada
| | - Anna Cho
- Department of Botany, University of British Columbia, Vancouver, V6T 1Z4, British Columbia, Canada
| | - Patrick J Keeling
- Department of Botany, University of British Columbia, Vancouver, V6T 1Z4, British Columbia, Canada
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4
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Han Y, Guo C, Guan X, McMinn A, Liu L, Zheng G, Jiang Y, Liang Y, Shao H, Tian J, Wang M. Comparison of Deep-Sea Picoeukaryotic Composition Estimated from the V4 and V9 Regions of 18S rRNA Gene with a Focus on the Hadal Zone of the Mariana Trench. MICROBIAL ECOLOGY 2022; 83:34-47. [PMID: 33811505 DOI: 10.1007/s00248-021-01747-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 03/25/2021] [Indexed: 06/12/2023]
Abstract
Diversity of microbial eukaryotes is estimated largely based on sequencing analysis of the hypervariable regions of 18S rRNA genes. But the use of different regions of 18S rRNA genes as molecular markers may generate bias in diversity estimation. Here, we compared the differences between the two most widely used markers, V4 and V9 regions of the 18S rRNA gene, in describing the diversity of epipelagic, bathypelagic, and hadal picoeukaryotes in the Challenger Deep of the Mariana Trench, which is a unique and little explored environment. Generally, the V9 region identified more OTUs in deeper waters than V4, while the V4 region provided greater Shannon diversity than V9. In the epipelagic zone, where Alveolata was the dominant group, picoeukaryotic community compositions identified by V4 and V9 markers are similar at different taxonomic levels. However, in the deep waters, the results of the two datasets show clear differences. These differences were mainly contributed by Retaria, Fungi, and Bicosoecida. The primer targeting the V9 region has an advantage in amplifying Bicosoecids in the bathypelagic and hadal zone of the Mariana Trench, and its high abundance in V9 dataset pointed out the possibility of Bicosoecids as a dominant group in this environment. Chrysophyceae, Fungi, MALV-I, and Retaria were identified as the dominant picoeukaryotes in the bathypelagic and hadal zone and potentially play important roles in deep-sea microbial food webs and biogeochemical cycling by their phagotrophic, saprotrophic, and parasitic life styles. Overall, the use of different markers of 18S rRNA gene allows a better assessment and understanding of the picoeukaryotic diversity in deep-sea environments.
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Affiliation(s)
- Yuye Han
- College of Marine Life Sciences, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China
| | - Cui Guo
- College of Marine Life Sciences, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China.
- Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China.
| | - Xuran Guan
- College of Marine Life Sciences, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China
| | - Andrew McMinn
- College of Marine Life Sciences, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
| | - Lu Liu
- College of Marine Life Sciences, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China
| | - Guiliang Zheng
- College of Marine Life Sciences, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China
| | - Yong Jiang
- College of Marine Life Sciences, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China
- Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China
| | - Yantao Liang
- College of Marine Life Sciences, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China
- Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China
| | - Hongbing Shao
- College of Marine Life Sciences, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China
- Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China
| | - Jiwei Tian
- Key Laboratory of Physical Oceanography, Ministry of Education, Ocean University of China, Qingdao, China
- Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Min Wang
- College of Marine Life Sciences, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China.
- Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China.
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5
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Anslan S, Sachs M, Rancilhac L, Brinkmann H, Petersen J, Künzel S, Schwarz A, Arndt H, Kerney R, Vences M. Diversity and substrate-specificity of green algae and other micro-eukaryotes colonizing amphibian clutches in Germany, revealed by DNA metabarcoding. Naturwissenschaften 2021; 108:29. [PMID: 34181110 PMCID: PMC8238718 DOI: 10.1007/s00114-021-01734-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 03/20/2021] [Accepted: 05/02/2021] [Indexed: 02/17/2023]
Abstract
Amphibian clutches are colonized by diverse but poorly studied communities of micro-organisms. One of the most noted ones is the unicellular green alga, Oophila amblystomatis, but the occurrence and role of other micro-organisms in the capsular chamber surrounding amphibian clutches have remained largely unstudied. Here, we undertook a multi-marker DNA metabarcoding study to characterize the community of algae and other micro-eukaryotes associated with agile frog (Rana dalmatina) clutches. Samplings were performed at three small ponds in Germany, from four substrates: water, sediment, tree leaves from the bottom of the pond, and R. dalmatina clutches. Sampling substrate strongly determined the community compositions of algae and other micro-eukaryotes. Therefore, as expected, the frog clutch-associated communities formed clearly distinct clusters. Clutch-associated communities in our study were structured by a plethora of not only green algae, but also diatoms and other ochrophytes. The most abundant operational taxonomic units (OTUs) in clutch samples were taxa from Chlamydomonas, Oophila, but also from Nitzschia and other ochrophytes. Sequences of Oophila "Clade B" were found exclusively in clutches. Based on additional phylogenetic analyses of 18S rDNA and of a matrix of 18 nuclear genes derived from transcriptomes, we confirmed in our samples the existence of two distinct clades of green algae assigned to Oophila in past studies. We hypothesize that "Clade B" algae correspond to the true Oophila, whereas "Clade A" algae are a series of Chlorococcum species that, along with other green algae, ochrophytes and protists, colonize amphibian clutches opportunistically and are often cultured from clutch samples due to their robust growth performance. The clutch-associated communities were subject to filtering by sampling location, suggesting that the taxa colonizing amphibian clutches can drastically differ depending on environmental conditions.
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Affiliation(s)
- Sten Anslan
- Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany.
| | - Maria Sachs
- Institute of Zoology, University of Cologne, Zülpicherstr. 47b, 50674, Köln, Germany
| | - Lois Rancilhac
- Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
| | - Henner Brinkmann
- Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Inhoffenstraße 7B, 38124, Braunschweig, Germany
| | - Jörn Petersen
- Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Inhoffenstraße 7B, 38124, Braunschweig, Germany
| | - Sven Künzel
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, 24306, Plön, Germany
| | - Anja Schwarz
- Institute of Geosystems and Bioindication, Technische Universität Braunschweig, Braunschweig, Germany
| | - Hartmut Arndt
- Institute of Zoology, University of Cologne, Zülpicherstr. 47b, 50674, Köln, Germany
| | - Ryan Kerney
- Department of Biology, Gettysburg College, Gettysburg, PA, USA
| | - Miguel Vences
- Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
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6
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Schoenle A, Hohlfeld M, Hermanns K, Mahé F, de Vargas C, Nitsche F, Arndt H. High and specific diversity of protists in the deep-sea basins dominated by diplonemids, kinetoplastids, ciliates and foraminiferans. Commun Biol 2021; 4:501. [PMID: 33893386 PMCID: PMC8065057 DOI: 10.1038/s42003-021-02012-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 03/08/2021] [Indexed: 02/02/2023] Open
Abstract
Heterotrophic protists (unicellular eukaryotes) form a major link from bacteria and algae to higher trophic levels in the sunlit ocean. Their role on the deep seafloor, however, is only fragmentarily understood, despite their potential key function for global carbon cycling. Using the approach of combined DNA metabarcoding and cultivation-based surveys of 11 deep-sea regions, we show that protist communities, mostly overlooked in current deep-sea foodweb models, are highly specific, locally diverse and have little overlap to pelagic communities. Besides traditionally considered foraminiferans, tiny protists including diplonemids, kinetoplastids and ciliates were genetically highly diverse considerably exceeding the diversity of metazoans. Deep-sea protists, including many parasitic species, represent thus one of the most diverse biodiversity compartments of the Earth system, forming an essential link to metazoans.
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Affiliation(s)
- Alexandra Schoenle
- University of Cologne, Institute of Zoology, General Ecology, Cologne, Germany.
| | - Manon Hohlfeld
- University of Cologne, Institute of Zoology, General Ecology, Cologne, Germany
| | - Karoline Hermanns
- University of Cologne, Institute of Zoology, General Ecology, Cologne, Germany
| | - Frédéric Mahé
- CIRAD, UMR BGPI, Montpellier, France
- BGPI, Univ Montpellier, CIRAD, IRD, Montpellier SupAgro, Montpellier, France
| | - Colomban de Vargas
- CNRS, Sorbonne Université, Station Biologique de Roscoff, UMR7144, ECOMAP-Ecology of Marine Plankton, Roscoff, France
- Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/ Tara GOSEE, Paris, France
| | - Frank Nitsche
- University of Cologne, Institute of Zoology, General Ecology, Cologne, Germany
| | - Hartmut Arndt
- University of Cologne, Institute of Zoology, General Ecology, Cologne, Germany.
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7
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Kostygov AY, Karnkowska A, Votýpka J, Tashyreva D, Maciszewski K, Yurchenko V, Lukeš J. Euglenozoa: taxonomy, diversity and ecology, symbioses and viruses. Open Biol 2021; 11:200407. [PMID: 33715388 PMCID: PMC8061765 DOI: 10.1098/rsob.200407] [Citation(s) in RCA: 92] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Euglenozoa is a species-rich group of protists, which have extremely diverse lifestyles and a range of features that distinguish them from other eukaryotes. They are composed of free-living and parasitic kinetoplastids, mostly free-living diplonemids, heterotrophic and photosynthetic euglenids, as well as deep-sea symbiontids. Although they form a well-supported monophyletic group, these morphologically rather distinct groups are almost never treated together in a comparative manner, as attempted here. We present an updated taxonomy, complemented by photos of representative species, with notes on diversity, distribution and biology of euglenozoans. For kinetoplastids, we propose a significantly modified taxonomy that reflects the latest findings. Finally, we summarize what is known about viruses infecting euglenozoans, as well as their relationships with ecto- and endosymbiotic bacteria.
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Affiliation(s)
- Alexei Y Kostygov
- Life Science Research Centre, Faculty of Science, University of Ostrava, Ostrava, Czech Republic.,Zoological Institute, Russian Academy of Sciences, St Petersburg, Russia
| | - Anna Karnkowska
- Institute of Evolutionary Biology, Faculty of Biology, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland
| | - Jan Votýpka
- Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic.,Department of Parasitology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Daria Tashyreva
- Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
| | - Kacper Maciszewski
- Institute of Evolutionary Biology, Faculty of Biology, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland
| | - Vyacheslav Yurchenko
- Life Science Research Centre, Faculty of Science, University of Ostrava, Ostrava, Czech Republic.,Martsinovsky Institute of Medical Parasitology, Tropical and Vector Borne Diseases, Sechenov University, Moscow, Russia
| | - Julius Lukeš
- Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic.,Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
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8
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Lax G, Kolisko M, Eglit Y, Lee WJ, Yubuki N, Karnkowska A, Leander BS, Burger G, Keeling PJ, Simpson AGB. Multigene phylogenetics of euglenids based on single-cell transcriptomics of diverse phagotrophs. Mol Phylogenet Evol 2021; 159:107088. [PMID: 33545276 DOI: 10.1016/j.ympev.2021.107088] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 01/24/2021] [Accepted: 01/26/2021] [Indexed: 12/22/2022]
Abstract
Euglenids are a well-known group of single-celled eukaryotes, with phototrophic, osmotrophic and phagotrophic members. Phagotrophs represent most of the phylogenetic diversity of euglenids, and gave rise to the phototrophs and osmotrophs, but their evolutionary relationships are poorly understood. Symbiontids, in contrast, are anaerobes that are alternatively inferred to be derived euglenids, or a separate euglenozoan group. Most phylogenetic studies of euglenids have examined the SSU rDNA only, which is often highly divergent. Also, many phagotrophic euglenids (and symbiontids) are uncultured, restricting collection of other molecular data. We generated transcriptome data for 28 taxa, mostly using a single-cell approach, and conducted the first multigene phylogenetic analyses of euglenids to include phagotrophs and symbiontids. Euglenids are recovered as monophyletic, with symbiontids forming an independent branch within Euglenozoa. Spirocuta, the clade of flexible euglenids that contains both the phototrophs (Euglenophyceae) and osmotrophs (Aphagea), is robustly resolved, with the ploeotid Olkasia as its sister group, forming the new taxon Olkaspira. Ploeotids are paraphyletic, although Ploeotiidae (represented by Ploeotia spp.), Lentomonas, and Keelungia form a robust clade (new taxon Alistosa). Petalomonadida branches robustly as sister to other euglenids in outgroup-rooted analyses. Within Spirocuta, Euglenophyceae is a robust clade that includes Rapaza, and Anisonemia is a well-supported monophyletic group containing Anisonemidae (Anisonema and Dinema spp.), 'Heteronema II' (represented by H. vittatum), and a clade of Neometanema plus Aphagea. Among 'peranemid' phagotrophs, Chasmostoma branches with included Urceolus, and Peranema with the undescribed 'Jenningsia II', while other relationships are weakly supported and consequently the closest sister group to Euglenophyceae remains unresolved. Our results are inconsistent with recent inferences that Entosiphon is the evolutionarily pivotal sister either to other euglenids, or to Spirocuta. At least three transitions between posterior and anterior flagellar gliding occurred in euglenids, with the phylogenetic positions and directions of those transitions remaining ambiguous.
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Affiliation(s)
- G Lax
- Department of Biology, and Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Canada; Department of Botany, University of British Columbia, Vancouver, Canada(1)
| | - M Kolisko
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Y Eglit
- Department of Biology, and Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Canada
| | - W J Lee
- Department of Environment and Energy Engineering, Kyungnam University, Changwon, Republic of Korea
| | - N Yubuki
- Unité d'Ecologie Systématique et Evolution, CNRS, Université Paris-Saclay, Orsay, France; Department of Zoology, University of British Columbia, Vancouver, Canada
| | - A Karnkowska
- Institute of Evolutionary Biology, Faculty of Biology, University of Warsaw, Poland
| | - B S Leander
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - G Burger
- Robert-Cedergren Centre for Bioinformatics and Genomics, Biochemistry Department, Université de Montréal, Montréal, Canada
| | - P J Keeling
- Department of Botany, University of British Columbia, Vancouver, Canada(1)
| | - A G B Simpson
- Department of Biology, and Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Canada.
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9
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Lax G, Simpson AGB. The Molecular Diversity of Phagotrophic Euglenids Examined Using Single-cell Methods. Protist 2020; 171:125757. [PMID: 33126020 DOI: 10.1016/j.protis.2020.125757] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 07/29/2020] [Accepted: 08/05/2020] [Indexed: 01/16/2023]
Abstract
Euglenids are a diverse group of euglenozoan flagellates that includes phototrophs, osmotrophs, and phagotrophs. Despite making up most of the phylogenetic diversity of euglenids, phagotrophs remain understudied, and recent work has focused on 'deep-branching' groups. Spirocuta is the large clade encompassing all flexible euglenids including the phototroph and primary osmotroph clades, plus various phagotrophs. Understanding the phylogenetic diversity of phagotrophic spirocutes is crucial for tracing euglenid evolution, including how phototrophs arose. We used single-cell approaches to greatly increase sampling of SSU rDNA for phagotrophic euglenids, particularly spirocutes, including the first sequences from Urceolus, Jenningsia, Chasmostoma, and Sphenomonas, and expanded coverage for Dinema and Heteronema sensu lato, amongst others. Urceolus monophyly is unconfirmed. Organisms referred to Jenningsia form two distinct clades. Heteronema vittatum and similar cells branch separately from Heteronema (c.f.) globuliferum and Teloprocta/Heteronema scaphurum, while Dinema appears as 2-3 clades. Sphenomonas is monophyletic and the deepest branch within Petalomonadida. The census of genera markedly underestimates the phylogenetic diversity of phagotrophs, but taxonomic restraint is necessary when sequences are not available from type species or reasonable surrogates. SSU rDNA phylogenies do not resolve most deep relationships within Spirocuta, but identify units of diversity to sample in future multigene analyses.
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Affiliation(s)
- Gordon Lax
- Department of Biology, and Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, NS, Canada
| | - Alastair G B Simpson
- Department of Biology, and Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, NS, Canada.
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10
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Gooday AJ, Schoenle A, Dolan JR, Arndt H. Protist diversity and function in the dark ocean - Challenging the paradigms of deep-sea ecology with special emphasis on foraminiferans and naked protists. Eur J Protistol 2020; 75:125721. [PMID: 32575029 DOI: 10.1016/j.ejop.2020.125721] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 05/13/2020] [Accepted: 05/21/2020] [Indexed: 11/27/2022]
Abstract
The dark ocean and the underlying deep seafloor together represent the largest environment on this planet, comprising about 80% of the oceanic volume and covering more than two-thirds of the Earth's surface, as well as hosting a major part of the total biosphere. Emerging evidence suggests that these vast pelagic and benthic habitats play a major role in ocean biogeochemistry and represent an "untapped reservoir" of high genetic and metabolic microbial diversity. Due to its huge volume, the water column of the dark ocean is the largest reservoir of organic carbon in the biosphere and likely plays a major role in the global carbon budget. The dark ocean and the seafloor beneath it are also home to a largely enigmatic food web comprising little-known and sometimes spectacular organisms, mainly prokaryotes and protists. This review considers the globally important role of pelagic and benthic protists across all protistan size classes in the deep-sea realm, with a focus on their taxonomy, diversity, and physiological properties, including their role in deep microbial food webs. We argue that, given the important contribution that protists must make to deep-sea biodiversity and ecosystem processes, they should not be overlooked in biological studies of the deep ocean.
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Affiliation(s)
- Andrew J Gooday
- National Oceanography Centre, University of Southampton Waterfront Campus, Southampton, UK; Life Sciences Department, Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Alexandra Schoenle
- University of Cologne, Institute of Zoology, General Ecology, 50674 Cologne, Germany
| | - John R Dolan
- Sorbonne Université, CNRS UMR 7093, Laboratoroire d'Océanographie de Villefranche-sur-Mer, Villefranche-sur-Mer, France
| | - Hartmut Arndt
- University of Cologne, Institute of Zoology, General Ecology, 50674 Cologne, Germany.
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