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  • 1
    Digitale Medien
    Digitale Medien
    MICROBIAL DIVERSITY: Domains and Kingdoms (1996)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Ecology, Evolution, and Systematics 27 (1996), S. 569-595 
    Details
    ISSN: 0066-4162
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Notizen: Abstract With the discovery of the eukaryote nucleus, all living organisms were neatly divided into prokaryotes, which lacked a nucleus, and eukaryotes, which possessed it. As data derived directly from the genome became available, it was clear that prokaryotes were comprised of two groups, Eubacteria and Archaebacteria. These were subsequently renamed at the new taxonomic level of Domain as Bacteria and Archaea, with the eukaryotes named as the Eucarya Domain. The interrelationships of the three Domains are still subject to discussion and evaluation, as is their monophyly. Further data, drawn from various protein sequences, suggest conflicting schemes, and resolution may not be straightforward. Additionally, Bacteria and Archaea as well as Eucarya are largely based on organisms already in culture. Investigation of the potentially enormous quantity of uncultured organisms in nature is likely to have as broad-ranging implications as the exploration of new protein sequences.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.ecolsys.27.1.569
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  • 2
    Digitale Medien
    Digitale Medien
    A mitochondrial-like targeting signal on the hydrogenosomal malic enzyme from the anaerobic fungus Neocallimastix frontalis: support for the hypothesis that hydrogenosomes are modified mitochondria (1997)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The hydrogenosomal malic enzyme (ME) was purified from the anaerobic fungus Neocallimastix frontalis. Using reverse genetics, the corresponding cDNA was isolated and characterized. The deduced amino acid sequence of the ME showed high similarity to ME from metazoa, plants and protists. Putative functional domains for malate and NAD+/NADP+ binding were identified. Phylogenetic analysis of the deduced amino acid sequence of the new ME suggests that it is homologous to reference bacterial and eukaryotic ME. Most interestingly, the cDNA codes for a protein which contains a 27-amino-acid N-terminus which is not present on the purified mature protein. This presequence shares features with known mitochondrial targeting signals, including an enrichment in Ala, Leu, Ser, and Arg, and the presence of an Arg at position –2 relative to amino acid 1 of the mature protein. This is the first report of a mitochondrial-like targeting signal on a hydrogenosomal enzyme from an anaerobic fungus and provides support for the hypothesis that hydrogenosomes in Neocallimastix frontalis might be modified mitochondria.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.1891553.x
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  • 3
    Digitale Medien
    Digitale Medien
    Massive differential expansion of the Trichomonas vaginalis adaptin genomic complement (2005)
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    Details
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Membrane transport is crucial to eukaryotic cell function and its evolution is likely to be critical for eukaryogenesis. Tetrameric adaptin complexes form part of the transport machinery, selecting cargo for transport through the late secretory and endocytic systems. With a few protistan exceptions, the majority of adaptin studies have been performed on animal and yeast models. Trypanosomatids and yeast have a minimal complement of adaptin genes, while humans and Arabidopsis show a moderate expansion. This expansion is functional, with adaptin subunit isoforms substituting combinatorially into their complex to provide novel localization. To address questions of evolution, parasitology and comparative cell biology, we examined the adaptin complexes of the sexually transmitted parasite Trichomonas vaginalis. In coordination with the T. vaginalis genome project at The Institute for Genomic Research, we identified all adaptin genes in the current 3.3X genome coverage data (). Surprisingly, T. vaginalis has massively and differentially expanded its adaptin arsenal, with six times as many genes as other unicellular organisms examined and three times as many multicellar organisms. Eight Trichomonas adaptins have been confirmed by cDNA, demonstrating concurrent expression of the same gene. Phylogenetic analysis shows that the duplications giving rise to the various adaptin subfamilies occurred prior to the last common ancestor of diverse protists. Our data provide important insight into the evolution of the adaptin complex and the complexity of the Trichomonas late secretory/endocytic system. The differential expansion may illustrate the relative functional importance of the adaptin subfamilies to Trichomonas and be a model in which to study the lesser expansion seen in other eukaryotes. Finally, the size of the expansion, and the concurrent expression of at least one gene, suggests that the combinatorial nature of the adaptin complex may be more important than previously expected.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1550-7408.2005.05202003_1_18.x
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  • 4
    Digitale Medien
    Digitale Medien
    Not the most basal eukaryotes: challenges and pitfalls affecting the placement of Giardia and Trichomonas (2005)
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    Details
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Diplomonads (including Giardia) and parabasalids (including Trichomonas) have traditionally been seen as the deepest-branching eukaryotes, on the evidence of apparently simple ultrastructural morphology, and small subunit ribosomal RNA trees. However, this position does not appear to be well supported, especially in the light of the discoveries of apparent mitochondrial remnants in Giardia and Trichomonas. We systematically re-analysed protein data, and show here that their traditional placement may be due to a combination of factors acting on data sets (narrow taxon sampling) and on genes (rate heterogeneity and compositional heterogeneity, mutational saturation). Our data found no consistent support for either Giardia or Trichomonas being basal eukaryotes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1550-7408.2005.05202003_1_79.x
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  • 5
    Digitale Medien
    Digitale Medien
    A mitochondrial remnant in the microsporidian Trachipleistophora hominis (2002)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 418 (2002), S. 865-869 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Microsporidia are obligate intracellular parasites of several eukaryotes. They have a highly complex and unique infection apparatus but otherwise appear structurally simple. Microsporidia are thought to lack typical eukaryotic organelles, such as mitochondria and peroxisomes. This has been ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/nature00949
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  • 6
    Digitale Medien
    Digitale Medien
    Eukaryotic evolution, changes and challenges (2006)
    [s.l.] : Nature Publishing Group
    Nature 440 (2006), S. 623-630 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The idea that some eukaryotes primitively lacked mitochondria and were true intermediates in the prokaryote-to-eukaryote transition was an exciting prospect. It spawned major advances in understanding anaerobic and parasitic eukaryotes and those with previously overlooked mitochondria. But the ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/nature04546
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  • 7
    Digitale Medien
    Digitale Medien
    Evolutionary biology Early evolution comes full circle (2004)
    [s.l.] : Nature Publishing Group
    Nature 431 (2004), S. 134-137 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Charles Darwin described the evolutionary process in terms of trees, with natural variation producing diversity among progeny and natural selection shaping that diversity along a series of branches over time. But in the microbial world things are different, and various schemes have been devised to ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/431134a
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  • 8
    Digitale Medien
    Digitale Medien
    Molecular evolution A hydrogen-producing mitochondrion (1998)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 396 (1998), S. 517-519 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Dark, damp (and sometimes smelly) places harbour some of nature's most curious eukaryotes. The likes of swamps and intestines are swarming with mostly single-celled eukaryotes (protists) that, like all cells, must produce ATP to survive. Yet these places lack enough oxygen to sustain ATP synthesis ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/24994
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  • 9
    Digitale Medien
    Digitale Medien
    Systematic and morphological diversity of endosymbiotic methanogens in anaerobic ciliates (1993)
    Springer
    Antonie van Leeuwenhoek 64 (1993), S. 261-271 
    Details
    ISSN: 1572-9699
    Schlagwort(e): endosymbionts ; anaerobic protozoa ; methanogens ; 16S rRNA ; coadaptation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The identities and taxonomic diversity of the endosymbiotic methanogens from the anaerobic protozoaMetopus contortus, Metopus striatus, Metopus palaeformis, Trimyema sp. andPelomyxa palustris were determined by comparative analysis of their 16S ribosomal RNA sequences. Fluorescent oligonucleotide probes were designed to bind to the symbiont rRNA sequences and to provide direct visual evidence of their origins from methanogenic archaea contained within the host cells. Confocal microscopy was used to analyze the morphology of the endosymbionts in whole cells ofMetopus palaeformis, Metopus contortus, Trimyema sp. andCyclidium porcatum. The endosymbionts are taxonomically diverse and are drawn from three different genera;Methanobacterium, Methanocorpusculum andMethanoplanus. In every case the symbionts are closely related to, but different from, free-living methanogens for which sequences are available. It is thus apparent that symbioses have been formed repeatedly and independently. Ciliates which are unrelated to each other (Trimyema sp. andMetopus contortus) may contain symbionts which are closely related, and congeneric ciliates (Metopus palaeformis andM. contortus) may contain symbionts which are distantly related to each other. This suggests that some of the symbiotic associations must be relatively recent. For example, at least one of the symbioses inMetopus must postdate the speciation ofM. palaeformis andM. contortus. Despite this,Metopus contortus, Trimyema sp., Cyclidium porcatum and their respective endosymbionts show sophisticated morphological interactions which probably facilitate the exchange of materials between the partners.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00873086
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  • 10
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    Coupling of diversification and pH adaptation during the evolution of terrestrial Thaumarchaeota (2015)
    National Academy of Sciences
    Details
    Publikationsdatum: 2015-07-13
    Beschreibung: The Thaumarchaeota is an abundant and ubiquitous phylum of archaea that plays a major role in the global nitrogen cycle. Previous analyses of the ammonia monooxygenase gene amoA suggest that pH is an important driver of niche specialization in these organisms. Although the ecological distribution and ecophysiology of extant Thaumarchaeota have been studied extensively, the evolutionary rise of these prokaryotes to ecological dominance in many habitats remains poorly understood. To characterize processes leading to their diversification, we investigated coevolutionary relationships between amoA, a conserved marker gene for Thaumarchaeota, and soil characteristics, by using deep sequencing and comprehensive environmental data in Bayesian comparative phylogenetics. These analyses reveal a large and rapid increase in diversification rates during early thaumarchaeotal evolution; this finding was verified by independent analyses of 16S rRNA. Our findings suggest that the entire Thaumarchaeota diversification regime was strikingly coupled to pH adaptation but less clearly correlated with several other tested environmental factors. Interestingly, the early radiation event coincided with a period of pH adaptation that enabled the terrestrial Thaumarchaeota ancestor to initially move from neutral to more acidic and alkaline conditions. In contrast to classic evolutionary models, whereby niches become rapidly filled after adaptive radiation, global diversification rates have remained stably high in Thaumarchaeota during the past 400–700 million years, suggesting an ongoing high rate of niche formation or switching for these microbes. Our study highlights the enduring importance of environmental adaptation during thaumarchaeotal evolution and, to our knowledge, is the first to link evolutionary diversification to environmental adaptation in a prokaryotic phylum.
    Print ISSN: 0027-8424
    Digitale ISSN: 1091-6490
    Thema: Biologie , Medizin , Allgemeine Naturwissenschaft
    Publiziert von National Academy of Sciences
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