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  • Springer  (4)
  • ASLO (Association for the Sciences of Limnology and Oceanography)  (1)
  • 1
    Publikationsdatum: 2017-04-13
    Beschreibung: Two new oxaphenalenone dimers, talaromycesone A (1) and talaromycesone B (2), and a new isopentenyl xanthenone, talaroxanthenone (3), together with six known diphenyl ether derivatives, e.g., Δ1′,3′,-1′-dehydroxypenicillide (4), 1′,2′-dehydropenicillide (5), vermixocin A (6), vermixocin B (7), 3′-methoxy-1′2′-dehydropenicillide (8), and AS-186c (9), were isolated from the culture broth and mycelia of a marine fungus Talaromyces sp. strain LF458. Compound 2 represents the first example of 1-nor oxaphenalenone dimer carbon skeleton. All isolated compounds were subjected to bioactivity assays. Compounds 1, 2, and 9 exhibited potent antibacterial activities with IC50 3.70, 17.36, and 1.34 μM, respectively, against human pathogenic Staphylococcus strains. Compounds 1, 3, and 9 displayed potent acetylcholinesterase inhibitory activities with IC50 7.49, 1.61, and 2.60 μM, respectively. Interestingly, phosphodiesterase PDE-4B2 was inhibited by compounds 3 (IC50 7.25 μM) and 9 (IC50 2.63 μM).
    Materialart: Article , PeerReviewed
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  • 2
    Publikationsdatum: 2018-01-19
    Beschreibung: Though spirochetes have been repeatedly found in marine sponges and other invertebrates, little attention has been paid to the specificity of this association. This study demonstrates that different genoand morphotypes of spirochetes can reside within the same sponge individual and develop in considerable numbers. Specimens of the calcareous sponge Clathrina clathrus collected from the Adriatic Sea off Rovinj (Croatia) were found to harbor spirochete-like bacteria, which were characterized by scanning electron microscopy (SEM), 16S rRNA gene analysis, and catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH). Two novel spirochete sequence types related to the Brachyspiraceae could be retrieved. By use of specifically designed CARD-FISH probes, the C. clathrus-associated sequences could be assigned to a linear and a helical spirochete morphotype. Both were located within the sponge mesohyl and resembled the spirochete-like cells identified by SEM. In addition, from a Clathrina sp., most likely C. coriacea, that originated from Indonesian coastal waters, four different spirochete type sequences were recovered. Two of these also affiliated with the Brachyspiraceae, the other two were found associated with the Spirochaetaceae, one with the genera Borrelia and Cristispira.
    Materialart: Article , PeerReviewed
    Format: text
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  • 3
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    ASLO (Association for the Sciences of Limnology and Oceanography)
    In:  Limnology and Oceanography, 50 (2). pp. 598-606.
    Publikationsdatum: 2019-09-23
    Beschreibung: At Hook Ridge hydrothermal vent, a new species of Sclerolinum (Monilifera, Siboglinidae) was found at a water depth of 1,045 m. On the basis of investigations of multicores and gravity cores, the species habitat is characterized. Sclerolinum does not occur in sediments that are most strongly influenced by hydrothermal fluids, probably because of high temperature (up to 49°C) and precipitation of siliceous crusts. About 800 individuals m-2 occur in sediments that are only weakly exposed to hydrothermal flow and have the following characteristics: 20°C (15 cm sediment depth) to 21.5°C (bottom water), 18-40 cm yr-1 advection rates, pH 5.5, 〈25 µmol L-1 methane, 〈170 µmol L-1 sulfide, and 〈0.0054 mol m-2 yr-1 sulfide flux. Comparison with geochemical data from other reducing sediments indicates that the two groups of Siboglinidae, Monilifera and Frenulata, occur in sediments with low sulfide concentration and flux. In contrast, sulfurbased chemosynthetic organisms that typically occur at hydrothermal vents and cold seeps (e.g., Vestimentifera, vesicomyid clams, and bacterial mats) occur in sediments with higher sulfide availability; threshold values are around 500 µmol L-1 sulfide and 0.1 mol m-2 yr-1 sulfide fluxes. We did not find typical hydrothermal vent species at Hook Ridge hydrothermal vent, which might be explained by the unfavorable physicochemical habitat: At sites inhabited by Sclerolinum, sulfide availability appears to be too low, whereas at sites with higher sulfide availability, the temperatures might be too high, siliceous crust precipitation could preclude their occurrence, or both.
    Materialart: Article , PeerReviewed
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  • 4
    Publikationsdatum: 2017-03-22
    Beschreibung: A stable and specific bacterial community was shown to be associated with the Mediterranean sponge Chondrilla nucula. The associated bacterial communities were demonstrated to be highly similar for all studied specimens regardless of sampling time and geographical region. In addition, analysis of 16S rDNA clone libraries revealed three constantly C. nucula-associated bacterial phylotypes belonging to the Acidobacteria, the Gamma- and Deltaproteobacteria present in sponge specimens from two Mediterranean regions with distinct water masses (Ligurian Sea and Adriatic Sea). For the first time, candidate division TM7 bacteria were found in marine sponges. A major part (79%) of the C. nucula-derived 16S rDNA sequences were closely related to other sponge-associated bacteria. Phylogenetic analysis identified 14 16S rRNA gene sequence clusters, seven of which consisted of exclusively sponge-derived sequences, whereas the other seven clusters contained additional environmental sequences. This study adds to a growing database on the stability and variability of microbial consortia associated with marine sponges.
    Materialart: Article , PeerReviewed
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  • 5
    Publikationsdatum: 2018-01-19
    Beschreibung: The Makran accretionary complex shows a distinct bottom-simulating reflector, indicating a thick gas-hydrate-bearing horizon between the deformational front and about 1350 m water depth which seals off the upward flow of gas-charged fluids. A field of presently inactive mud diapirs with elevations up to 65 m was discovered in the abyssal plain seawards of the deformation front, suggesting that in the past conditions were favorable for periodic but localized vigorous mud diapirism. Regional destabilization of the gas hydrate leading to focused flow was observed where deep-penetrating, active faults reach the base of the gas-hydrate layer, as in a deeply incised submarine canyon (2100–2500 m water depth). At this location we discovered seeps of methane and H2S-rich fluids associated with chemoautotrophic vent faunas (e.g., Calyptogena sp.). Driven by the accretionary wedge dynamics, the landward part of the gas-hydrate layer below the Makran margin is being progressively uplifted. Due to reduced hydrostatic pressure and rising ocean bottom-water temperatures, gas hydrates are progressively destabilized and dissociated into hydrate water, methane and H2S. Sediment temperatures lie outside the methane stability field wherever water depth is less than 800 m. Above this depth, upward migration of fluids to the seafloor is unimpeded, thus explaining the abundance of randomly distributed gas seeps observed at water depths of 350 to 800 m.
    Materialart: Article , PeerReviewed
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