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  • 1
    Keywords: Forschungsbericht ; Nahrungsergänzungsmittel ; Algen ; Neuroprotektivum
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource (8 Seiten, 445,42 KB) , Diagramme
    Language: German
    Note: Förderkennzeichen BMBF 031B0367A , Verbundnummer 01180416 , Unterschiede zwischen dem gedruckten Dokument und der elektronischen Ressource können nicht ausgeschlossen werden
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  • 2
    Online Resource
    Online Resource
    Bremerhaven : Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
    Keywords: Forschungsbericht ; Eukaryoten
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource (16 Seiten, 1,99 MB) , Diagramme, Illustration
    Language: English
    Note: Förderkennzeichen BMBF 161B0561A+B [neu] - 031B0561A+B [alt] , Verbundnummer 01182402 , Unterschiede zwischen dem gedruckten Dokument und der elektronischen Ressource können nicht ausgeschlossen werden
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  • 3
    In: Biofouling, London [u.a.] : Taylor & Francis, 1988, 26(2010), 3, Seite 247-255, 1029-2454
    In: volume:26
    In: year:2010
    In: number:3
    In: pages:247-255
    Description / Table of Contents: This study investigated whether surface-associated compounds isolated from the macroalga Fucus vesiculosus had the potential to mediate microbial and/or macrobial epibiosis similar to that on the natural alga. To selectively yield thallus-associated compounds and avoid contamination by intracellular algal compounds, cell lysis was monitored by surface microscopy of algal cells and chemical profiling of algal surface extracts by coupled gas chromatography mass spectroscopy. The optimized extraction resulted in polar and non-polar algal surface extracts. The non-polar surface extract was immobilized in hydrogel, the polar surface extract was homogeneously perfused through the gel to ensure a temporally constant delivery of polar extract components. During a 7 day field trial, bacterial biofilms were formed on control gels and gels featuring polar and/or non-polar extract components. PERMANOVA revealed that bacterial community profiles on controls and on gels featuring polar or non-polar extract were significantly different from the profile on F. vesiculosus, while the profile on the gels bearing both polar and non-polar extracts was not. Moreover, the polar surface extracts inhibited the settlement of barnacle cyprids. Considering the pronounced effects of bacterial biofilms on invertebrate larval settlement, these results suggest that algal surface chemistry affects macrofouling not only directly but also indirectly, via its control of biofilm formation and composition.
    Type of Medium: Online Resource
    Pages: Ill., graph. Darst
    ISSN: 1029-2454
    Language: English
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  • 4
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Different bacterial community profiles were observed on the soft coral Dendronephthya sp. and an inanimate reference site using terminal restriction fragment length polymorphism analysis of bacterial community DNA. To correlate the observation with a chemical defense mechanism against bacterial epibiosis, antibacterial effects of coral tissue extracts and waterborne products of coral-associated bacterial isolates (11 morphotypes) were tested against indigenous benthic bacterial isolates (33 morphotypes) obtained in the vicinity of the coral colonies. The coral tissue extracts and waterborne products of coral-associated bacteria inhibited growth and attachment of indigenous bacterial isolates, suggesting an endogenous chemical and an exogenous biological mechanism against bacterial epibiosis in this soft coral.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: It has been postulated that a variety of physically undefended marine invertebrates have evolved strategies to control microbial epibiosis chemically. Ecologically meaningful experiments that demonstrate chemically mediated antibacterial effects are difficult due to the small number of cultivable bacteria. Based on the example of three sponges, this study introduces a culture-independent methodology to investigate chemically mediated control of bacterial epibiosis by analyzing the natural bacterial consortia. Organic extracts of sponges were immobilized in hydrogels at tissue level concentrations and exposed to the same source of natural seawater for bacterial colonization. Terminal restriction fragment length polymorphism analysis of polymerase chain reaction-amplified bacterial community DNA obtained from these gels was shown to be a useful tool to study bacterial community shifts in response to sponge metabolites by comparing bacterial ribotypes obtained from the gel surfaces. Several terminal restriction fragments were absent relative to the control suggesting that settlement of specific bacteria was prevented. On the other hand, additional fragments occurred in some treatments, coinciding with higher bacterial abundance evidenced by DAPI counts of bacterial cells, indicating the bacterial utilization of sponge extract components. The advantages of this method are (1) a culture-independent approach, i.e. the assessment of antimicrobial activities against natural bacterial communities, (2) no restriction to particular modes of microbial colonization, i.e. antibiotic and repellant, and (3) the in situ assessment of antimicrobial compounds under flow conditions.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2017-01-05
    Description: The macroalga Fucus vesiculosus carries a specific community of surface bacteria. To identify chemical compounds that possibly mediate abundance and community composition of algae-associated bacteria, we tested the effect of surface-available algal compounds on bacterial settlement and community composition under field conditions. Compounds on algal thalli were separated from the surface by extraction with organic solvents and investigated on growth inhibition and settlement of bacterial isolates. Based on in vitro data, partially purified extract fractions were then exposed to bacterial colonizers in vivo followed by bacterial enumeration and community analysis. The polar fraction of the algal surface extract revealed a significant profouling effect for Vibrionales, whereas the nonpolar fraction containing the xanthophyll pigment fucoxanthin and other unidentified nonpolar surface compounds revealed a significant 80% reduction of surface colonizing bacteria. The analysis of bacterial surface communities by 454 pyrosequencing demonstrated that the antifouling activity of nonpolar algal surface compounds was targeting the abundance of natural bacterial colonizers rather than the relative composition of bacterial members within the community. Moreover, the bacterial community composition on F.vesiculosus was markedly different from artificial control substrates and chemically manipulated experimental treatments, suggesting that other, nonextractable surface features and/or physical properties render algal-specific epiphytic bacterial communities.
    Type: Article , PeerReviewed
    Format: text
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  • 7
    Publication Date: 2018-05-31
    Description: The abundance and diversity of microorganisms on the surface of the tropical green macroalga Caulerpa racemosa var. turbinata and the effect of algal surface and waterborne compounds on fouling organisms were investigated both in laboratory and field experiments. As shown via electron microscopic enumeration, the abundance of epibiotic bacteria and diatoms on algal frond surfaces was not significantly different from the reference biofilms harvested from stones in the C. racemosa habitat. The analysis of Terminal Restriction Fragment Length Polymorphism of DNA from algal surface-associated bacterial communities revealed that despite a similar abundance of these bacteria, the community profile on algal frond surfaces differed significantly from that of inanimate, undefended substrates. These results suggest that the alga regulate the occurrence of certain bacterial ribotypes. This result was in accordance with the fact that different bacterial communities formed on the artificial substrata (i.e. Petri dishes) placed in the C. racemosa habitat and alga-free control sites. Neither C. racemosa conditioned seawater (CCW) nor hexane surface extracts affected the growth of bacterial isolates from biofilms. However, only CCW exhibited a toxic effect on the larvae of the fouling polychaete Hydroides elegans, and evoked abnormal larval development in a concentration-dependent fashion. At sublethal concentrations, the 〈1 kD fraction of CCW inhibited the larval settlement of H. elegans and the bryozoan Bugula neritina. Caulerpenyne, the prominent bioactive metabolite in the genus Caulerpa, was not detected in CCW by chromatographic procedures. Our data suggest that waterborne compounds other than caulerpenyne are involved in the chemical defense of the alga C. racemosa.
    Type: Article , PeerReviewed
    Format: text
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  • 8
    Publication Date: 2019-09-23
    Description: Marine macroalgae are constantly exposed to epibacterial colonizers. The epiphytic bacterial patterns and their temporal and spatial variability on host algae are poorly understood. To investigate the interaction between marine macroalgae and epiphytic bacteria, this study tested if the composition of epibacterial communities on different macroalgae was specific and persisted under varying biotic and abiotic environmental conditions over a 2-year observation time frame. Epibacterial communities on the co-occurring macroalgae Fucus vesiculosus, Gracilaria vermiculophylla and Ulva intestinalis were repeatedly sampled in summer and winter of 2007 and 2008. The epibacterial community composition was analysed by denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene libraries. Epibacterial community profiles did not only differ significantly at each sampling interval among algal species, but also showed consistent seasonal differences on each algal species at a bacterial phylum level. These compositional patterns re-occurred at the same season of two consecutive years. Within replicates of the same algal species, the composition of bacterial phyla was subject to shifts at the bacterial species level, both within the same season but at different years and between different seasons. However, 7–16% of sequences were identified as species specific to the host alga. These findings demonstrate that marine macroalgae harbour species-specific and temporally adapted epiphytic bacterial biofilms on their surfaces. Since several algal host-specific bacteria were highly similar to other bacteria known to either avoid subsequent colonization by eukaryotic larvae or to exhibit potent antibacterial activities, algal host-specific bacterial associations are expected to play an important role for marine macroalgae.
    Type: Article , PeerReviewed
    Format: text
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  • 9
    Publication Date: 2022-01-31
    Description: “Infochemicals” (information‐conveying chemicals) dominate much of the underwater communication in biological systems. They influence the movement and behavior of organisms, the ecological interactions between and across populations, and the trophic structure of marine food webs. However, relative to their terrestrial equivalents, the wider ecological and economic importance of marine infochemicals remains understudied and a concerted, cross‐disciplinary effort is needed to reveal the full potential of marine chemical ecology. We highlight current challenges with specific examples and suggest how research on the chemical ecology of marine organisms could provide opportunities for implementing new management solutions for future “blue growth” (the sustainable use of ocean resources) and maintaining healthy marine ecosystems.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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  • 10
    Publication Date: 2024-02-07
    Description: Host-microbe interactions play crucial roles in marine ecosystems. However, we still have very little understanding of the mechanisms that govern these relationships, the evolutionary processes that shape them, and their ecological consequences. The holobiont concept is a renewed paradigm in biology that can help to describe and understand these complex systems. It posits that a host and its associated microbiota with which it interacts, form a holobiont, and have to be studied together as a coherent biological and functional unit to understand its biology, ecology, and evolution. Here we discuss critical concepts and opportunities in marine holobiont research and identify key challenges in the field. We highlight the potential economic, sociological, and environmental impacts of the holobiont concept in marine biological, evolutionary, and environmental sciences. Given the connectivity and the unexplored biodiversity specific to marine ecosystems, a deeper understanding of such complex systems requires further technological and conceptual advances, e.g., the development of controlled experimental model systems for holobionts from all major lineages and the modeling of (info)chemical-mediated interactions between organisms. Here we propose that one significant challenge is to bridge cross-disciplinary research on tractable model systems in order to address key ecological and evolutionary questions. This first step is crucial to decipher the main drivers of the dynamics and evolution of holobionts and to account for the holobiont concept in applied areas, such as the conservation, management, and exploitation of marine ecosystems and resources, where practical solutions to predict and mitigate the impact of human activities are more important than ever.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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