Phylogenetic relationships between the Acantharea and the Polycystinea: A molecular perspective on Haeckel’s Radiolaria

Zettler, Linda A. Amaral; Sogin, Mitchell L.; Caron, David A.

doi:10.1073/pnas.94.21.11411

Cited by 56 publications

(13 citation statements)

References 26 publications

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“…The monophyly of Mycetozoa (slime molds) themselves has remained an open question for a long time. The major groups that belong to the slime molds (cellular and myxogastrid slime molds) are phenotypically quite divergent and in a number of SSU rDNA studies they branched independently from each other from the eukaryotic trunk (Hinkle et al 1994; Leipe et al 1993; Zettler, Sogin, and Caron 1997). Only recent work using EF‐1α and the combination of several molecular markers (Baldauf and Doolittle 1997; Baldauf et al 2000) demonstrated a robust monophyly of this group.…”

Section: Discussionmentioning

confidence: 99%

The Phylogenetic Position of the Pelobiont Mastigamoeba balamuthi Based on Sequences of rDNA and Translation Elongation Factors EF‐1α and EF‐2

Arisue

Hashimoto

Lee

et al. 2002

J Eukaryotic Microbiology

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The taxonomic position and phylogenetic relationships of the Pelobionta, an amitochondriate amoeboflagellate group, are not yet completely settled. To provide more information, we obtained sequences for the large subunit rDNA gene, the gene for translation elongation factor 1alpha, and for a large part of the gene encoding translation elongation factor 2 from a representative of this group, Mastigamoeba balamuthi (formerly Phreatamoeba balamuthi). The gene for the large subunit rDNA was unusually large compared to those of other protists, a phenomenon that had previously been observed for the gene encoding the small subunit rDNA. Phylogenetic reconstruction using a maximum likelihood method was performed with these sequences, as well as the gene encoding the small subunit rDNA. When evaluated individually, the M. balamuthi genes for the small and large subunit rDNAs and elongation factor 1alpha had a most recent common ancestor with either the Mycetozoa (slime molds) or with Entamoeba histolytica. A clade formed by M. balamuthi, E. histolytica, and Mycetozoa was not rejected statistically for any of the sequences. A combined maximum likelihood analysis using 3,935 positions from all molecules suggested that these three taxonomic units form a robust clade. We were unable to resolve the closest group to this clade using the combined analysis. These findings support the notion, which had previously been proposed primarily on cytological evidence, that both M. balamuthi and E. histolytica are closely related to the Mycetozoa and that these three together represent a major eukaryotic lineage.

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Section: Discussionmentioning

confidence: 99%

The Phylogenetic Position of the Pelobiont Mastigamoeba balamuthi Based on Sequences of rDNA and Translation Elongation Factors EF‐1α and EF‐2

Arisue

Hashimoto

Lee

et al. 2002

J Eukaryotic Microbiology

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“…The Acantharea sequence found in Lake Bourget occurs near marine sequences. The organisms appear to take up species-specific positions in the water column, often at considerable depth, and it has been reported that strontium sulfate is necessary for the formation of all Acantharea skeletons (58).…”

Section: Discussionmentioning

confidence: 99%

Unexpected Importance of Potential Parasites in the Composition of the Freshwater Small-Eukaryote Community

Lepère

Domaizon

Debroas

2008

Appl Environ Microbiol

127

138

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The diversity of small eukaryotes (0.2 to 5 m) in a mesotrophic lake (Lake Bourget) was investigated using 18S rRNA gene library construction and fluorescent in situ hybridization coupled with tyramide signal amplification (TSA-FISH). Samples collected from the epilimnion on two dates were used to extend a data set previously obtained using similar approaches for lakes with a range of trophic types. A high level of diversity was recorded for this system with intermediate trophic status, and the main sequences from Lake Bourget were affiliated with ciliates (maximum, 19% of the operational taxonomic units [OTUs]), cryptophytes (33%), stramenopiles (13.2%), and cercozoa (9%). Although the comparison of TSA-FISH results and clone libraries suggested that the level of Chlorophyceae may have been underestimated using PCR with 18S rRNA primers, heterotrophic organisms dominated the small-eukaryote assemblage. We found that a large fraction of the sequences belonged to potential parasites of freshwater phytoplankton, including sequences affiliated with fungi and Perkinsozoa. On average, these sequences represented 30% of the OTUs (40% of the clones) obtained for each of two dates for Lake Bourget. Our results provide information on lacustrine small-eukaryote diversity and structure, adding to the phylogenetic data available for lakes with various trophic types.It has been recognized that the eukaryotic component of picoplankton plays a critical role in the functioning of aquatic ecosystems (29, 34). However, numerous members of this community possess very few morphological characteristics that can be used for identification by traditional microscopic methods. Thus, molecular techniques offer a very useful alternative for the elucidation and description of picoeukaryotic plankton diversity in aquatic environments. Numerous studies have revealed new lineages and unexpected diversity of picoeukaryotes in the open ocean (7, 29, 37), coastal areas (35, 46), anaerobic sediments (5), acid rivers (2), and deep-sea vents (11,30). However, the diversity, distribution, and natural abundance of small-eukaryote taxa in freshwater systems are still poorly known. Nevertheless, a few recent studies have reported high diversity of 18S rRNA sequences in this community (Ͻ5 m) in lakes and general dominance of heterotrophic cells in the small-eukaryote assemblage (25,27,45). A salient feature of the first findings is the presence of sequences affiliated with parasitic groups in lakes with different trophic types (25). This suggests that the ecological impact of parasitism may have been underestimated in marine systems (31) and also in freshwater systems. However, the data on lacustrine small-eukaryote diversity are still largely incomplete, and additional investigation of the composition and organization of freshwater small-eukaryote assemblages is essential; in particular, no data are available for mesotrophic lakes.To draw up an inventory of lacustrine picoplankton (Ͻ5 m) over a full trophic status range (from oligotrophic to hypereutro...

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“…The phylogenetic position of Radiolaria proposed by Haeckel, especially the skeletal Polycystinea and Acantharea, has generated considerable debate, with a few environmental sequences provoking recent phylogenetic reassessments (34,70). Nikolaev et al (51) describe three major lineages: Acantharea, Polycystinea, and Taxopodida.…”

Section: Diversitymentioning

confidence: 99%

Diversity and Distribution of Marine Microbial Eukaryotes in the Arctic Ocean and Adjacent Seas

Lovejoy

Massana

Pedrós-Alió

2006

Appl Environ Microbiol

265

235

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We analyzed microbial eukaryote diversity in perennially cold arctic marine waters by using 18S rRNA gene clone libraries. Samples were collected during concurrent oceanographic missions to opposite sides of the Arctic Ocean Basin and encompassed five distinct water masses. Two deep water Arctic Ocean sites and the convergence of the Greenland, Norwegian, and Barents Seas were sampled from 28 August to 2 September 2002. An additional sample was obtained from the Beaufort Sea (Canada) in early October 2002. The ribotypes were diverse, with different communities among sites and between the upper mixed layer and just below the halocline. Eukaryotes from the remote Canada Basin contained new phylotypes belonging to the radiolarian orders Acantharea, Polycystinea, and Taxopodida. A novel group within the photosynthetic stramenopiles was also identified. One sample closest to the interior of the Canada Basin yielded only four major taxa, and all but two of the sequences recovered belonged to the polar diatom Fragilariopsis and a radiolarian. Overall, 42% of the sequences were <98% similar to any sequences in GenBank. Moreover, 15% of these were <95% similar to previously recovered sequences, which is indicative of endemic or undersampled taxa in the North Polar environment. The cold, stable Arctic Ocean is a threatened environment, and climate change could result in significant loss of global microbial biodiversity.The Arctic Ocean (AO) and surrounding seas have traditionally been thought of as being dominated by large phytoplankton of Ͼ20 m (67); however, recent studies show that these waters have active microbial food webs that are often dominated by cells of Ͻ3 m (37, 57) and that cells of Ͻ5 m are responsible for much of the carbon fixation over wide regions of the Arctic Basin (23, 31). The Arctic Ocean is an enclosed sea with a cold, moderately fresh (Ͻ30 practical salinity units) upper mixed layer of 30 to 60 m. These upper photic zone waters are separated from deeper waters by a strong halocline that is maintained by large riverine inputs and the annual formation and melting of sea ice (1). The physical isolation, perennially cold water temperatures (Ͻ0°C), and extreme annual light cycle provide a distinct marine habitat for microorganisms (15). 16S rRNA gene surveys have uncovered novel archaeal and eubacterial sequences from remote polar regions (6,7,12), confirming that these ambient conditions select for particular microorganisms, but there are no equivalent studies of microbial eukaryotes. North polar latitudes are predicted to warm rapidly as a result of global climate change and have already experienced significant impacts (2, 48). An assessment of current microbial diversity is therefore paramount for this region at this early stage in climate modification.Isolated and extreme environments have been important sources of novel phylotypes (33,47) that have contributed to the recent major reassessment of eukaryotic evolution (5). rRNA gene sequences from uncultured marine eukaryotes have also led to major...

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Phylogenetic relationships between the Acantharea and the Polycystinea: A molecular perspective on Haeckel’s Radiolaria

Cited by 56 publications

References 26 publications

The Phylogenetic Position of the Pelobiont Mastigamoeba balamuthi Based on Sequences of rDNA and Translation Elongation Factors EF‐1α and EF‐2

The Phylogenetic Position of the Pelobiont Mastigamoeba balamuthi Based on Sequences of rDNA and Translation Elongation Factors EF‐1α and EF‐2

Unexpected Importance of Potential Parasites in the Composition of the Freshwater Small-Eukaryote Community

Diversity and Distribution of Marine Microbial Eukaryotes in the Arctic Ocean and Adjacent Seas

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