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  • Articles  (4)
  • 2015-2019  (2)
  • 1985-1989  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Structural peculiarities of the body wall of Tubificoides benedii (Oligochaeta) and possible relations to its life in sulphidic sediments (1988)
    Springer
    Zoomorphology 108 (1988), S. 29-39 
    Details
    ISSN: 1432-234X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Tubificoides benedii [=Peloscolex benedeni] a ubiquitous tubificid from poorly oxygenated, often polluted coastal muds, is known to be exceptionally well adapted to sulphidic sediments. However, almost nothing is known about its structural peculiarities, such as the conspicuously papillate body surface and possible relations to its unusual ecology. As a consequence, a study of this abundant but extraordinary marine worm has been made with the use of light and electron microscopy. While many internal structures correspond to the general pattern of marine tubificids and are not mentioned here, the epidermis — cuticle complex is unusual. The thick cuticle forms numerous high leaf-shaped papillae covered by condensed, almost solid mucus caps. The intermediate furrows usually harbour many different bacteria embedded in mucus. This mucus cover is rich in precipitates containing sulphur and other xenobiotic substances. Together with the cuticular papillae it can be sloughed off in a “moulting process”. Epicuticular projections, usually typical of oligochaetes, are absent from most parts of the body except from the first and last segments. The epidermal cells often contain numerous extremely long and abnormally shaped mitochondria. The significance of the peculiar structure of the body wall and the distinct “moulting” are discussed in the light of the ecological situation of these tubificids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00312212
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Some aspects of the ecophysiology of Tubificoides benedii and ultrastructural observations on endocuticular bacteria (1987)
    Springer
    Hydrobiologia 155 (1987), S. 161-161 
    Details
    ISSN: 1573-5117
    Keywords: ultrastructure ; anaerobiosis ; marine oligochaetes ; filamentous epibacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tubificoides benedii is regularly found in sulphide-rich sediments with extremely low oxygen tensions and can tolerate anaerobic conditions for several days. Although the anaerobic energy production of marine invertebrates has been well studied, almost nothing is known about the anaerobic metabolism of marine oligochaetes. Preliminary results after measuring end-products during anaerobic incubation show that in contrast to all previously examined marine facultative anaerobe invertebrates T. benedii degrades malate during anaerobiosis. Also, the concentration of free amino acids is extremely low for a marine organism. Low levels of free amino acids could be concomitant with malate utilization: the utilization of the amino acid aspartate (as observed in all other examined marine invertebrates) seems to be excluded by the low concentrations of aspartate and other amino acids in T. benedii. The physiological lab studies were supplemented by ecological investigations in the field and laboratory on the vertical distribution of T. benedii. 90% of the population was always found within the first few cm below the sediment surface. Aquarium observations showed that the posterior end of the worm projects above the sediment surface, where it slowly waves back and forth. This behavior points towards an intestinal respiration. The described orientation, an intestinal respiration and anaerobic energy production could be advantageous in sulphide-rich sediments where O2 only penetrates a few mm into the sediment. The worm can easily inhabit the first three to four cm by holding its tail in the upper oxygenated sediment and water. Here it would be able to feed on the rich quantities of bacteria at the anoxic-oxic interface and yet still keep up an aerobic metabolism. In addition, its ability to produce energy anaerobically would allow T. benedii to dwell in deeper anoxic sediments for limited periods of time or to survive complete O2 absence that could develop during low tide. The posterior ends of T. benedii found in a sulphide-rich habitat in the German Wadden Sea were covered with filamentous epibacteria (Dubilier, 1986). Electron microscopy showed that the bacteria were anchored in the cuticle. The association is apparently not pathogenic whereas positive forms of interaction can be envisioned.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00025644
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    Paper (German National Licenses)
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  • 3
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    Functional diversity enables multiple symbiont strains to coexist in deep-sea mussels (2019)
    In:  EPIC3nature microbiology, 4, pp. 2487-2497
    Details
    Publication Date: 2020-02-14
    Description: Genetic diversity of closely related free-living microorganisms is widespread and underpins ecosystem functioning, but most evolutionary theories predict that it destabilizes intimate mutualisms. Accordingly, strain diversity is assumed to be highly restricted in intracellular bacteria associated with animals. Here, we sequenced metagenomes and metatranscriptomes of 18 Bathymodiolus mussel individuals from four species, covering their known distribution range at deep-sea hydrothermal vents in the Atlantic. We show that as many as 16 strains of intracellular, sulfur-oxidizing symbionts coexist in individual Bathymodiolus mussels. Co-occurring symbiont strains differed extensively in key functions, such as the use of energy and nutrient sources, electron acceptors and viral defence mechanisms. Most strain-specific genes were expressed, highlighting their potential to affect fitness. We show that fine-scale diversity is pervasive in Bathymodiolus sulfur-oxidizing symbionts, and hypothesize that it may be widespread in low-cost symbioses where the environment, rather than the host, feeds the symbionts.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev , info:eu-repo/semantics/article
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    PAPER (OA)
  • 4
    facet.materialart.
    Unknown
    Functional diversity enables multiple symbiont strains to coexist in deep-sea mussels (2019)
    In:  EPIC3Nature Microbiology, 4(12), pp. 2487-2497, ISSN: 2058-5276
    Details
    Publication Date: 2021-09-25
    Description: Genetic diversity of closely related free-living microorganisms is widespread and underpins ecosystem functioning, but most evolutionary theories predict that it destabilizes intimate mutualisms. Accordingly, strain diversity is assumed to be highly restricted in intracellular bacteria associated with animals. Here, we sequenced metagenomes and metatranscriptomes of 18 Bathymodiolus mussel individuals from four species, covering their known distribution range at deep-sea hydrothermal vents in the Atlantic. We show that as many as 16 strains of intracellular, sulfur-oxidizing symbionts coexist in individual Bathymodiolus mussels. Co-occurring symbiont strains differed extensively in key functions, such as the use of energy and nutrient sources, electron acceptors and viral defence mechanisms. Most strain-specific genes were expressed, highlighting their potential to affect fitness. We show that fine-scale diversity is pervasive in Bathymodiolus sulfur-oxidizing symbionts, and hypothesize that it may be widespread in low-cost symbioses where the environment, rather than the host, feeds the symbionts.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev , info:eu-repo/semantics/article
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