A Survey of Flagellate Diversity at Four Deep‐Sea Hydrothermal Vents in the Eastern Pacific Ocean Using Structural and Molecular Approaches

Atkins, Michael S.; Teske, Andreas; Anderson, O. Roger

doi:10.1111/j.1550-7408.2000.tb00067.x

Cited by 132 publications

(112 citation statements)

References 57 publications

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“…For example, within the ciliates, we recovered sequences (C1 E007 and A1 E033) that are closely related to sequences from the anaerobes Metopus contortus and Trimyema compressum, respectively. In addition, the detection of rRNA sequences from diverse flagellates is consistent with published accounts of viable flagellate protists from several hydrothermal vent sites, including Guaymas Basin (11). Rapid rates of reproduction allow these small flagellates to colonize temporally and spatially variable habitats such as these fine-particle, hydrothermally heated sediments.…”

Section: Resultssupporting

confidence: 68%

Benthic eukaryotic diversity in the Guaymas Basin hydrothermal vent environment

Edgcomb

Kysela

Teske

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

345

337

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Molecular microbial ecology studies have revealed remarkable prokaryotic diversity in extreme hydrothermal marine environments. There are no comparable reports of culture-independent surveys of eukaryotic life in warm, anoxic marine sediments. By using sequence comparisons of PCR-amplified small subunit ribosomal RNAs, we characterized eukaryotic diversity in hydrothermal vent environments of Guaymas Basin in the Gulf of California. Many sequences from these anoxic sediments and the overlaying seawater represent previously uncharacterized protists, including early branching eukaryotic lineages or extended diversity within described taxa. At least two mechanisms, with overlapping consequences, account for the eukaryotic community structure of this environment. The adaptation to anoxic environments is evidenced by specific affinity of environmental sequences to aerotolerant anaerobic species in molecular trees. This pattern is superimposed against a background of widely distributed aerophilic and aerotolerant protists, some of which may migrate into and survive in the sediment whereas others (e.g., phototrophs) are simply deposited by sedimentary processes. In contrast, bacterial populations in these sediments are primarily characteristic of anoxic, reduced, hydrocarbon-rich sedimentary habitats. P hylogenetic studies of ribosomal RNAs from cultured species imply that large evolutionary distances separate major groups of protists. Certain aerotolerant anaerobic parasites seem to represent early diverging lineages in the eukaryotic line of descent (1). Because they do not require atmospheric levels of oxygen for growth, these organisms lack mitochondria and peroxisomes. The absence of these features in the most divergent eukaryotic lineages and the thermophilic phenotype of the deepest prokaryotic branches suggest that warm, anoxic environments surrounding deep-sea hydrothermal vents might support novel and diverse eukaryotic communities. Little information about the phenotypic and evolutionary diversity of free-living protists from anoxic marine environments is available. Most studies of protist diversity rely upon morphological characters to differentiate between genera. However, culturebased studies and microscopical criteria cannot provide quantitative measures of genetic diversity. More significantly, these methods frequently do not provide comprehensive profiles of community composition. Cultivation-independent molecular surveys of eukaryotic microbial diversity based on comparisons of PCR amplicons of small subunit (SSU) rRNA genes from marine pelagic environments reveal a microbial world with few taxonomically assignable protists (2, 3). There are no analogous molecular surveys of eukaryotic microbial diversity in anoxic, deep-sea sediments.Here, we report the results of a molecular survey of eukaryotic community SSU rRNA gene composition in sediments and the seawater interface proximal to a deep-sea hydrothermal vent. The study site is Guaymas Basin, Gulf of California, which is a hydrothermally active env...

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Section: Resultssupporting

confidence: 68%

Benthic eukaryotic diversity in the Guaymas Basin hydrothermal vent environment

Edgcomb

Kysela

Teske

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

345

337

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“…Nevertheless, given that kinetoplastid sequences are so abundant and diverse in our samples, the fact that not a single kinetoplastid phylotype had been identified in Pacific samples, for which a total of 276 sequences was analyzed (5), might indicate a different geographic distribution or, at the least, that kinetoplastids have a higher representation in Atlantic systems. In the latter sense, one bodonid species, Rhynchomonas nasuta, was isolated from Pacific vents (19).…”

Section: Resultsmentioning

confidence: 99%

Autochthonous eukaryotic diversity in hydrothermal sediment and experimental microcolonizers at the Mid-Atlantic Ridge

López‐García

Piégay

Gail

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

326

279

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The diversity and mode of life of microbial eukaryotes in hydrothermal systems is very poorly known. We carried out a molecular survey based on 18S ribosomal RNA genes of eukaryotes present in different hydrothermal niches at the Mid-Atlantic Ridge. These included metal-rich and rare-earth-element-rich hydrothermal sediments of the Rainbow site, fluid-seawater mixing regions, and colonization devices (microcolonizers) containing organic, ironrich, and porous mineral substrates that were exposed for 15 days to a fluid source. We identified considerable phylogenetic diversity, both at kingdom level and within kinetoplastids and alveolates. None of our sequences affiliates to photosynthesizing lineages, suggesting that we are targeting only autochthonous deep-sea communities. Although sediment harbored most phylogenetic diversity, microcolonizers predominantly contained bodonids and ciliates, indicating that these protists pioneer the colonization process. Given the large variety of divergent lineages detected within the alveolates in deep-sea plankton, hydrothermal sediments, and vents, alveolates seem to dominate the deep ocean in terms of diversity. Compared with data from the Pacific Guaymas basin, some protist lineages seem ubiquitous in hydrothermal areas, whereas others, notably kinetoplastid lineages, very abundant and diverse in our samples, so far have been detected only in Atlantic systems. Unexpectedly, although alvinellid polychaetes are considered endemic of Pacific vents, we detected alvinellidrelated sequences at the fluid-seawater interface and in microcolonizers. This finding can boost further studies on deep-sea vent animal biology and biogeography.C ompared with prokaryotes, microbial eukaryotes thriving in extreme environments have rarely been studied. This fact is partly because of the difficulties imposed by classical cultivation approaches. Recent eukaryotic diversity surveys based on 18S rRNA are revealing an unexpected variety of often divergent lineages in different biotopes, including some extreme environments (1-6). The only available molecular survey of microbial eukaryotes from deep-sea vents was recently carried out in hydrothermal sediments from the Pacific Guaymas basin and revealed an important diversity of hitherto unknown lineages (5). Surprisingly, many of these sequences affiliated to typical photosynthesizing groups (such as green algae or diatoms), leading to the conclusion that autochthonous eukaryotes cannot be distinguished from those deposited from the water column (5). There were two objectives in this study. First, we aimed at characterizing the diversity of autochthonous microbial eukaryotes from Mid-Atlantic Ridge hydrothermal systems. Thus, we have carried out a molecular survey of hydrothermal sediment and seawater-fluid interface. These results should constitute a first base for comparison with data from the Pacific systems. To date, whereas prokaryotes seem ubiquitous in different oceanic regions (7), possibly including vent areas, metazoans are subject to a defi...

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“…Careful examination by light microscopy ensured the absence of contaminating protozoa, yeasts or fungal hyphae. Microscopic observations were compared with several manuals and publications displaying identified protozoa (Page, 1988;Ekelund and Patterson, 1997;Tong et al, 1998;Atkins et al, 2000;Lee and Patterson, 2000). Approximately every 2 months, cultures were transferred to fresh medium.…”

Section: Isolation and Cultivationmentioning

confidence: 99%

Molecular comparison of cultivable protozoa from a pristine and a polycyclic aromatic hydrocarbon polluted site

Lara

Berney

Ekelund

et al. 2007

Soil Biology and Biochemistry

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We compared the abundance and diversity of cultivable protozoa (flagellates and amoebae) in a polycyclic aromatic hydrocarbon (PAH) polluted soil and an unpolluted control, by isolating and cultivating clonal strains. The number of cultivable protozoa was higher in the polluted soil; however, the polluted soil displayed an impoverished community, dominated by certain taxa, such as Acanthamoeba sp. We isolated a total of 31 protozoan strains to characterize them morphologically and by 18S rRNA gene sequence analysis. This approach, i.e. combining morphological and molecular information had the advantage of providing quantitative data, information on morphology but also an accurate positioning of the isolates in 18S rRNA trees.

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A Survey of Flagellate Diversity at Four Deep‐Sea Hydrothermal Vents in the Eastern Pacific Ocean Using Structural and Molecular Approaches

Cited by 132 publications

References 57 publications

Benthic eukaryotic diversity in the Guaymas Basin hydrothermal vent environment

Benthic eukaryotic diversity in the Guaymas Basin hydrothermal vent environment

Autochthonous eukaryotic diversity in hydrothermal sediment and experimental microcolonizers at the Mid-Atlantic Ridge

Molecular comparison of cultivable protozoa from a pristine and a polycyclic aromatic hydrocarbon polluted site

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