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  • 1
    Electronic Resource
    Electronic Resource
    The Jakobid Flagellates: Structural Features of Jakoba, Reclinomonas and Histiona and Implications for the Early Diversification of Eukaryotes (1993)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 40 (1993), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Jakobid flagellates are small, free-living, bacterivorous heterotrophs, with similar morphology, asexual reproduction, and nucleocytoplasmic ultrastructural features at interphase and during cell division. Jakoba is typified by aloricate trophic cells, each containing a branched mitochondrion with prominent nucleoids and flattened cristae. Reclinomonas and Histiona are characterized by loricate trophic cells, each with an unbranched mitochondrion without prominent nucleoids or otherwise differentiated regions and bearing tubular cristae. An undescribed genus is typified by aloricate cells, each with an unbranched mitochondrion bearing discoidal cristae. I propose, on the basis of cytoskeletal architecture and other structural and developmental features, that jakobids are ancestral mitochondrial protists, sister taxa to the amitochondnal retortamonads and ancestral to diverse lineages of mitochondrial eukaryotes. Application of different classification paradigms produces different family-level taxonomies for jakobids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1993.tb06120.x
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  • 2
    Electronic Resource
    Electronic Resource
    Two New Small-Subunit Ribosomal RNA Gene Lineages within the Subclass Gymnamoebia (2003)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 50 (2003), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Phylogenetic analysis of small-subunit ribosomal RNA gene sequences for gymnamoebae of the families Vexilliferidae, Paramoebidae, and Vannellidae identified two distinct lineages that are supported by gross morphological characters. This analysis indicates that paramoebids and vexilliferids are part of one lineage and that vannellids belong to another. A shared morphological character unique to the paramoebid/vexilliferid lineage members is the presence of dactylopodiate subpseudopodia. However, cell surface structures, normally used for taxonomic discrimination, range from simple hair-like filaments without any apparent organization (Neo-paramoeba), to hexagonal glycostyles (Vexillifera) or more elaborate surface scales (Korotnevella). Taxa within the vannellid lineage all lack subpseudopodia and appear flabellate, spatulate or linguif'orm while in locomotion. Cell surface structures of taxa within the vannellid lineage range from filaments organized into hexagonal arrays (Lingulamoeba, Platyamoeba) to pentagonal glycostyles (Cly-donella, Vannella). Vannellid lineage members of the genera Clydonella and Lingulamoeba were studied at the level of electron microscopy. Unique cell surface features validate these as genera distinct from Vannella and Platyamoeba. Genetic and ultrastructural data are used to discuss the phylogenetic interrelationships for the taxa studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2003.tb00122.x
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  • 3
    Electronic Resource
    Electronic Resource
    How Oxymonads Lost Their Groove: An Ultrastructural Comparison of Monocercomonoides and Excavate Taxa (2002)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 49 (2002), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Despite being amongst the more familiar groups of heterotrophic flagellates, the evolutionary affinities of oxymonads remain poorly understood. A re-interpretation of the cytoskeleton of the oxymonad Monocercomonoides hausmanni suggests that this organism has a similar Ultrastructural organisation to members of the informal assemblage ‘excavate taxa’. The preaxostyle, ‘Rl’ root, and ‘R2’ root of M. hausmanni are proposed to be homologous to the right, left, and anterior roots respectively of excavate taxa. The ‘paracrystalline’ portion of the preaxostyle, previously treated as unique to oxymonads, is proposed to be homologous to the I fibre of excavate taxa. Other non-microtubular fibres are identified that have both positional and substructurel similarity to the distinctive B and C fibres of excavate taxa. A homologue to the ‘singlet root’, otherwise distinctive for excavate taxa, is also proposed. The preaxostyle and C fibre homologue in Monocercomonoides are most similar to the homologous structures in Trimastix, suggesting a particularly close relationship. This supports and extends recent molecular phylogenetic findings that Trimastix and oxymonads form a clade. We conclude that oxymonads have an excavate ancestry, and that the‘excavate taxa’ sensu stricto form a paraphyletic assemblage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2002.tb00529.x
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  • 4
    Electronic Resource
    Electronic Resource
    Korotnevella hemistylolepis N. Sp. and Korotnevella monacantholepis N. Sp. (Paramoebidae), Two New Scale-covered Mesohaline Amoebae (2001)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 48 (2001), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Two new species of KorotnevellaGoodkov, 1988, Korotnevella hemistylolepis n. sp. and Korotnevella monacantholepis n. sp., are described from mesohaline ecosystems. The amoebae are characterized on the basis of light and electron microscopy with special emphasis on the structure of the basket scales, which have species-specific architecture. The two new species are the second and third ones recovered from environments other than freshwater. In terms of scale morphology they most closely resemble a freshwater species, Korotnevella bulla (Schaeffer, 1926) Goodkov, 1988. Two genus names, DactylamoebaKorotnev, 1880 and KorotnevellaGoodkov, 1988, are in current use. The latter name is preferred, pending rediscovery and characterization of Dactylamoeba elongataKorotnev, 1880, the type species of the genus. Korotnevella species can be divided into three groups on the basis of scale morphology, suggesting that the genus may not be monophyletic. A key to species is provided.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2001.tb00205.x
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  • 5
    Electronic Resource
    Electronic Resource
    The Nucleariid Amoebae: More Protists at the Animal-Fungal Boundary (2001)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 48 (2001), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Nucleariid amoebae are naked amoebae, generally characterized by a spherical or sometimes flattened body with radiating filopodia. Most species preferentially consume algal prey or cyanobacteria. Phylogenetic analyses of the small-subunit rRNA coding regions from four nucleariid amoebae place these species near the origin of the animal-fungal divergence, together with the choanofiagellate-Corallochytrium and the ichthyosporean clades. The species Nuclearia delicatula, N. moebiusi, and N. simplex form a monophyletic group, while ATCC 30864, tentatively but possibly incorrectly assigned to Nuclearia sp., represents a separate line of descent. These nucleariids are unrelated to the lineage containing the testate filose amoebae (Testaceafilosia). Our findings expand the morphological and phylogenetic diversity of protists at the animal-fungal divergence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2001.tb00317.x
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  • 6
    Electronic Resource
    Electronic Resource
    Malawimonas jakobiformis n. gen., n. sp. (Malawimonadidae n. fam.): A Jakoba-like Heterotrophic Nanoflagellate with Discoidal Mitochondrial Cristae (1999)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 46 (1999), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Malawimonas jakobiformis n. gen., n. sp., is established for a bacterivorous heterotrophic nanoflagellate isolated from the Malawi shore of Lake Nyasa (eastern Africa). Trophic stages observed were anteriorly biflagellate and naked. The posterior flagellum of a trophic cell resided in a conspicuous groove on the ventral surface, and bore a prominent vane. A Golgi stack and a mitochondrion with discoidal cristae were present anterior to the nucleus. The kinetid consisted of two short, slightly separated basal bodies, four microtubular roots, and associated fibers and bands. The three microtubular roots associated with the posterior basal body were associated with the ventral groove, while the single root associated with the anterior basal body gave rise to secondary cytoskeletal microtubules. Dividing cells became rounded, with persistent flagella. Cysts were uninucleate, and had thin organic walls without clearly differentiated apertures or ornamentation but with conspicuous attachment pads. Kinetid elements were present within cysts. On the basis of microscopical features, especially those of the kinetid, the nearest relatives of M. jakobiformis are the mitochondriate “jakobid” protists (families Histionidae and Jakobidae) and the amitochondriate retortamonads. Malawimonadidae n. fam. is established to accommodate this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1999.tb06070.x
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  • 7
    Electronic Resource
    Electronic Resource
    A Comparative Genomics Approach to the Evolution of Eukaryotes and their Mitochondria (1999)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 46 (1999), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The Organelle Genome Megasequencing Program (OGMP) investigates mitochondrial genome diversity and evolution by systematically determining the complete mitochondrial DNA (mtDNA) sequences of a phylogenetically broad selection of protists. The mtDNAs of lower fungi and choanoflagellates are being analyzed by the Fungal Mitochondrial Genome Project (FMGP), a sister project to the OGMP. Some of the most interesting protists include the jakobid flagellates Reclinomonas americana, Malawimonas jakobiformis, and Jakoba libera, which share ultrastructural similarities with amitochondriate retortamonads, and harbor mitochondrial genes not seen before in mtDNAs of other organisms. In R. americana and J. libera, gene clusters are found that resemble, to an unprecedented degree, the contiguous ribosomal protein operons str, S10, spc, and alpha of eubacteria. In addition, their mtDNAs code for an RNase P RNA that displays all the elements of a bacterial minimum consensus structure. This structure has been instrumental in detecting the rnpB gene in additional protists. Gene repertoire and gene order comparisons as well as multiple-gene phylogenies support the view of a single endosymbiotic origin of mitochondria, whose closest extant relatives are Rickettsia-type α-Proteobacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1999.tb04611.x
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  • 8
    Electronic Resource
    Electronic Resource
    An ancestral mitochondrial DNA resembling a eubacterial genome in miniature (1997)
    [s.l.] : Nature Publishing Group
    Nature 387 (1997), S. 493-497 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Currently, the inferred set of 'proto-mitochondrial genes' comprises 44 protein-coding genes that specify 23 components of complexes I-V of the electron transport chain, 18 mitoribosomal proteins, and 3 proteins involved in cytochrome c\ biogenesis (Table 1). In addition, mtDNA encodes up to 3 ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/387493a0
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  • 9
    Electronic Resource
    Electronic Resource
    Seeds of a universal tree (1991)
    [s.l.] : Nature Publishing Group
    Nature 350 (1991), S. 106-107 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] ACCORDING to the serial endosymbiosis theory, mitochondria and chloroplasts arose by intracellular symbioses between ancestral eukaryotes and free-living unicellular organ-isms. For these organelles the principle is now well established. But are they mono-phyletic or polyphyletic, and if ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/350106a0
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  • 10
    Electronic Resource
    Electronic Resource
    Intron-encoded open reading frame of the GIY-YIG subclass in a plastid gene (1995)
    Springer
    Current genetics 28 (1995), S. 97-99 
    Details
    ISSN: 1432-0983
    Keywords: GIY-YIG ORF ; Endonuclease ; Plastid ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Group-I introns, containing open reading frames (ORFs) that code for homing endonucleases, are widely distributed amongst eukaryotic organellar genomes. However, endonucleases of the GIY-YIG subclass have a restricted distribution in mitochondria and bacteriophages, and have never been observed in plastids. We have found the GIY-YIG motif in an intronic ORF within the previously published psbA gene sequence from Chlamydomonas reinhardtii chloroplasts. Based on phylogenetic analysis and an evaluation of amino-acid substitutions, this ORF is not closely related to any of the other GIY-YIG ORFs. These results suggest that GIY-YIG ORFs have a longer evolutionary history than previously assumed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00311888
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