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  • 1
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. The Myxogastria are common soil microorganisms with a life cycle comprised of a plasmodial trophic stage and large fruiting bodies generally visible with the unaided eye. Until now, their classification has been based exclusively on a combination of morphological, ultrastructural, and developmental characters. Our study is the first attempt to examine phylogenetic relationships among these taxa using molecular data. Partial small-subunit ribosomal RNA and/or elongation factor 1-alpha gene sequences were obtained from eleven, mostly field-collected species representing the five orders of Myxogastria. Nineteen sequences were obtained and subjected to phylogenetic analysis together with 10 sequences available from GenBank. Separate and combined analyses of the two data sets support the division of Myxogastria into three distinct groups. The most basal clade consists of the Echinosteliales, an order considered to have affinities with Protostelia. The three species examined possess unpigmented or slightly pigmented spores. The second group consists of Liceales and Trichiales, taxa characterized by the presence of clear, but pigmented, spores. The third group consists of the two remaining orders, Physarales and Stemonitales, both possessing dark spores. This suggests that spore pigmentation is an evolutionarily conservative character in myxogastrians, and that the simple morphology of echinostelids is not a derived feature.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Over the past few years, the use of cultivation-independent techniques to detect eukaryotic diversity has proven to be a powerful approach. Based on small-subunit ribosomal RNA (SSU rRNA) gene analyses, these studies have revealed the existence of an unexpected variety of new phylotypes. Some of them do not seem to be related to any molecularly described lineage, and have been proposed to represent novel eukaryotic kingdoms. In order to critically review the evolutionary importance of this novel high-level eukaryotic diversity and to test the potential technical and analytical pitfalls and limitations of eukaryotic environmental DNA surveys (EES), we analysed 484 environmental SSU rRNA gene sequences, including 81 new sequences from sediments of the river Seymaz (Geneva, Switzerland). Based on a detailed screening of an exhaustive alignment of SSU rRNA gene sequences and the phylogenetic re-analysis of previously published sequences using Bayesian methods, our results suggest that the number of novel higher-level taxa revealed by previous EES was over-estimated. Three main sources of errors are responsible for this situation, namely (1) the presence of undetected chimeric sequences; (2) the misplacement of several fast evolving sequences; and (3) the incomplete sampling of described, but yet unsequenced eukaryotes. EES undoubtedly contribute to unravel many novel eukaryotic lineages, but there is no clear evidence for a spectacular increase of the diversity at a megaevolutionary level. After our re-analysis, we found only five candidate lineages of possible novel high-level eukaryotic taxa. To ascertain their taxonomic status, however, the organisms themselves have to be identified now.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The origin of amoeboid protists is one of the greatest enigmas of eukaryotic phylogeny. Although it has long been accepted that amoeboid protists are polyphyletic, the lack of molecular data for many amoeboid taxa impeded their placement in the tree of life. We have sequenced the small-subunit ribosomal RNA and actin genes from a broad taxonomic sampling of amoeboid protists, including three lineages of heliozoans (Actinophryida, Desmothoracida, and Taxopodida) and one lineage of radiolarians (Phaeodarea) for which no molecular data were available yet. Phylogenetic analyses of our data show that (1) all lobose amoebae sequenced to date belong to the recently defined phylum Amoebozoa and (2) Heliozoa and Radiolaria both represent polyphyletic assemblages, as suggested by previous ultrastructural studies. However, although axopodia evolved at least five times independently during the evolution of eukaryotes, our study also reveals that most protists possessing filopodia, reticulopodia, and/or axopodia are closely related, and constitute a new supergroup of amoeboid protists, the Rhizaria.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Molecular sampling of the taxonomic diversity of the living world is nowadays a task of paramount importance. Heliozoa represents one of the major eukaryotic taxa, which remain significantly underrepresented in molecular databases. The term Heliozoa was coined to embrace organisms with a rounded body and stiff pseudopodia. Despite evidences from ultrastructural studies, which conclusively show the polyphyly of selected heliozoan groups, contemporary morphological systems retain Heliozoa as a monophyletic taxon. From the perspective of reconstructing the true phylogeny of Eukaryota, molecular approaches to analyse relationships within this large protist group are evidently necessary. Phylogenetic analysis of our data shows that the four heliozoan taxa branch either independently or within different eukaryotic phyla. The actinophryids (Actinosphaerium, Actinophrys) appear as a lineage of stramenopiles, while the desmothoracids (Clathrulina, Hedriocystis) branch within “core Cercozoa”. The position of both groups is strongly supported in all analyses and is congruent with ultrastructure-based taxonomic revisions. The centrohelids (Chlamydaster, Heterophrys, Pterocystis, and Raphidiophrys) do not seem to be related to any particular eukaryotic phylum, in agreement with a recent molecular study. The taxopodid Sticholonche was found to branch between Polycystinea and Acantharea, two classes of radiolarians. Results obtained in this study suggest that the heliozoan body form cannot be used as a diagnostic argument to unite Heliozoa. Instead, we discriminate between the three heliomorphic taxa of independent origin, Actinophryida, Desmothoracida and Sticholonche, and propose the novel higher rank taxon Centrohelida. The term Heliozoa should thus be used solely in historical context.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Lobose amoebae are abundant free-living protists and important pathogenic agents, yet their evolutionary history and position in the universal tree of life are poorly known. Molecular data for lobose amoebae are limited to a few species, and all phylogenetic studies published so far lacked representatives of many of their taxonomic groups. Here we analyse actin and small-subunit ribosomal RNA (SSU rRNA) gene sequences of a broad taxon sampling of naked, lobose amoebae. Our results support the existence of a monophyletic Amoebozoa clade, which comprises all lobose amoebae examined so far, as well as the amitochondriate pelobionts and entamoebids, and the slime molds. Both actin and SSU rRNA phylogenies distinguish two well-defined clades of amoebae, the “Gymnamoebia sensu stricto” and the Archamoebae (pelobionts+entamoebids), and one weakly supported and ill-resolved group comprising some naked, lobose amoebae and the Mycetozoa.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In his grand monography of Radiolaria, Ernst Haeckel originally placed Phaeodarea within the class Radiolaria, together with Acantharea and Polycystinea. Cytological and ultrastructural studies, however, questioned the monophyly of Radiolaria, suggesting the independent evolutionary origin of the three taxa. Some recent molecular analyses based on small subunit ribosomal RNA (SSU rRNA) sequences challenged this classification, supporting the sisterhood of Acantharea and Polycystinea. In order to further test the monophyly of all Haeckel's Radiolaria, and as no data on Phaeodarea were available, we sequenced the complete SSU rRNA gene of three Phaeodarea and three Polycystinea. Our analyses show that the monophyletic Phaeodarea clearly branch among Cercozoa, and confirm that Acantharea and Polycystinea share a common history. This result enhances the morphological variability within Cercozoa, a phylum already containing very heterogeneous groups of protists. Our study suggests that the ability to secrete SrSO4 and the organization of microtubules inside axopodia are better phylogenetic markers than the simple presence of a central capsule and axopodia.
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  • 7
    Publication Date: 2022-10-26
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Levin, L. A., Bett, B. J., Gates, A. R., Heimbach, P., Howe, B. M., Janssen, F., McCurdy, A., Ruhl, H. A., Snelgrove, P., Stocks, K., I., Bailey, D., Baumann-Pickering, S., Beaverson, C., Benfield, M. C., Booth, D. J., Carreiro-Silva, M., Colaco, A., Eble, M. C., Fowler, A. M., Gjerde, K. M., Jones, D. O. B., Katsumata, K., Kelley, D., Le Bris, N., Leonardi, A. P., Lejzerowicz, F., Macreadie, P., I., McLean, D., Meitz, F., Morato, T., Netburn, A., Pawlowski, J., Smith, C. R., Sun, S., Uchida, H., Vardaro, M. F., Venkatesan, R., & Weller, R. A. Global observing needs in the deep ocean. Frontiers in Marine Science, 6, (2019):241, doi: 10.3389/fmars.2019.00241.
    Description: The deep ocean below 200 m water depth is the least observed, but largest habitat on our planet by volume and area. Over 150 years of exploration has revealed that this dynamic system provides critical climate regulation, houses a wealth of energy, mineral, and biological resources, and represents a vast repository of biological diversity. A long history of deep-ocean exploration and observation led to the initial concept for the Deep-Ocean Observing Strategy (DOOS), under the auspices of the Global Ocean Observing System (GOOS). Here we discuss the scientific need for globally integrated deep-ocean observing, its status, and the key scientific questions and societal mandates driving observing requirements over the next decade. We consider the Essential Ocean Variables (EOVs) needed to address deep-ocean challenges within the physical, biogeochemical, and biological/ecosystem sciences according to the Framework for Ocean Observing (FOO), and map these onto scientific questions. Opportunities for new and expanded synergies among deep-ocean stakeholders are discussed, including academic-industry partnerships with the oil and gas, mining, cable and fishing industries, the ocean exploration and mapping community, and biodiversity conservation initiatives. Future deep-ocean observing will benefit from the greater integration across traditional disciplines and sectors, achieved through demonstration projects and facilitated reuse and repurposing of existing deep-sea data efforts. We highlight examples of existing and emerging deep-sea methods and technologies, noting key challenges associated with data volume, preservation, standardization, and accessibility. Emerging technologies relevant to deep-ocean sustainability and the blue economy include novel genomics approaches, imaging technologies, and ultra-deep hydrographic measurements. Capacity building will be necessary to integrate capabilities into programs and projects at a global scale. Progress can be facilitated by Open Science and Findable, Accessible, Interoperable, Reusable (FAIR) data principles and converge on agreed to data standards, practices, vocabularies, and registries. We envision expansion of the deep-ocean observing community to embrace the participation of academia, industry, NGOs, national governments, international governmental organizations, and the public at large in order to unlock critical knowledge contained in the deep ocean over coming decades, and to realize the mutual benefits of thoughtful deep-ocean observing for all elements of a sustainable ocean.
    Description: Preparation of this manuscript was supported by NNX16AJ87A (NASA) Consortium for Ocean Leadership, Sub-Award No. SA16-33. AC was supported by FCT-Investigador contract (IF/00029/2014/CP1230/CT0002). LL was supported by a NASA subaward from the Consortium for Ocean Leadership. AG and HR were supported by Horizon 2020, EU Project “EMSO Link” grant ID 731036. AG, BB, DJ, and HR contributions were supported by the UK Natural Environment Research Council Climate Linked Atlantic Section Science project (NE/R015953/1). JP was funded by the Swiss Network for International Studies, and the Swiss National Science Foundation (grant 31003A_179125). TM was supported by Program Investigador FCT (IF/01194/2013), IFCT Exploratory Project (IF/01194/2013/CP1199/CT0002), H2020 Atlas project (GA 678760), and the H2020 MERCES project (GA 689518). This is PMEL contribution number 4965.
    Keywords: Deep sea ; Ocean observation ; Blue economy ; Essential ocean variables ; Biodiversity ; Ocean sensors
    Repository Name: Woods Hole Open Access Server
    Type: Article
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