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  • 1
    Electronic Resource
    Electronic Resource
    Bacterial induction and inhibition of a fast mecrotic response in Gracilaria conferta (Rhodophyta) (1997)
    Springer
    Journal of applied phycology 9 (1997), S. 277-285 
    Details
    ISSN: 1573-5176
    Keywords: cefotaxim ; epiphytic bacteria ; Gracilaria ; seaweed-microbe interactions ; seaweed pathology ; Vancomycin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Of 45 bacterial isolates from healthy tips of Gracilaria conferta (Schousboe ex Montagne) J. et G. Feldmann, 29% were identified as ‘conditional inducers’ of an apical necrosis. That is, the isolates induced necrotic tips in G. conferta within 16 h after elimination of most of the resident microflora from the alga. Several disinfectants and antibiotics were screened for their ability to induce algal susceptibility to the bacteria and to suppress uncontrolled appearance of tip necrosis. Treatment with 100 mg L-1 Cefotaxim + 100 mg L-1Vancomycin over three days was the least damaging and most efficient. Tip necrosis was related to isolates of the Corynebacterium-Arthrobacter-group and to the Flavobacterium-Cytophaga-group. The damaging effect occurred due to the bacterial excretion of active agents and was not correlated with acapability to degrade agar. The damaging influence of four Cytophaga-likestrains was inhibited by 20 of 40 isolates. This protective effect was caused by very different organisms. In five of six cases examined further, the effect was not cellbound, but due to the excretion of agents. These were not antimicrobially active, but inactivated necrosis-inducing excretions. These results indicate that epiphytic bacterial degradation or inactivation of damaging agents is a protecting factor in Gracilaria, which prevents the alga from being harmed by epiphytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007990712925
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Endogenous and exogenous elicitors of a hypersensitive response in Gracilaria conferta (Rhodophyta) (2000)
    Springer
    Journal of applied phycology 12 (2000), S. 139-145 
    Details
    ISSN: 1573-5176
    Keywords: cellulose ; epiphytic bacteria ; Gracilaria conferta ; oligosaccharide ; peptide,plant-pathogen interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Certain forms of oligocellulose and certainbacterially excreted peptides were identified asendogenous and exogenous elicitors, respectively, ofa tip bleaching response in Gracilaria conferta(Schousboe ex Montagne) J. et G. Feldmann. Thehalf-maximal tip bleaching response was observed when31.1 μM cellobiose or 11.6 μM cellotetraosewere present in the growth medium. In contrast, noresponse was detected after exposure to glucose,cellotriose, cellopentaose or maltooligosaccharides.The response was thus strongly dependent on themolecular size of the oligocellulose and onlysaccharides that consisted of an even number ofglucose residues were elicitor-active. Three bacterialspecies that had earlier been identified as potentialinducers of the tip bleaching symptom excretedelicitor-active compounds into the growth medium.These compounds were protease-sensitive and thuspeptides or proteins. The tip bleaching-inducingcompound that was excreted by one Cytophaga-likeorganism was partially purified. It could be extractedfrom culture supernatants with chloroform and itsmolecular size was between 700 and 1500 Da,corresponding with a structure of 4–20 amino acids.Various endogenous and exogenous elicitors are thusrecognized by G. conferta and allow this alga torespond hypersensitively to the maceration of its cellwall skeleton or just to the presence of certainepiphytic organisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008119125911
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    Paper (German National Licenses)
    Fulltext
  • 3
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    In situ common garden assays demonstrate increased defense against natural fouling in non-native populations of the red seaweed Gracilaria vermiculophylla (2017)
    Springer
    In:  Marine Biology, 164 . Art.Nr.193.
    Details
    Publication Date: 2020-02-06
    Description: The susceptibility of native and non-native populations of the red alga Gracilaria vermiculophylla to fouling was compared in common garden experiments. Native and non-native algae were enclosed into dialysis membrane tubes, and the tubes were exposed to natural fouling. Fouling on the outside of the tubes was mediated by chemical compounds excreted by G. vermiculophylla that diffused through the membranes. Fouling pressure was significantly higher in the Kiel Fjord (non-native range) than in Akkeshi Bay (native range), but, at both sites, tubes containing non-native G. vermiculophylla were less fouled than those with native conspecifics. This is the first in situ evidence that susceptibility to fouling differs between native and non-native populations of an aquatic organism. The technique of enclosing organisms into dialysis tubes represents a simple, efficient and accurate way to test chemical antifouling defenses and could possibly be applied to other organisms.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00227-017-3226-6
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  • 4
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    Fluctuations in the strength of chemical antifouling defenses in a red macroalga in response to variations in epibiont colonization pressure (2018)
    Springer
    In:  Marine Biology, 165 (6). p. 107.
    Details
    Publication Date: 2021-02-08
    Description: Marine macroalgae in temperate regions are constantly exposed to colonization by fouling organisms, but the intensity of fouling fluctuates in time. We, therefore, hypothesized that a macroalgal species from these latitudes should be able to adjust its antifouling defense to the prevailing colonization pressure. To test this assumption, fouling pressure in the Western Baltic Sea as well as the activity of surface extracts gained from the non-native Gracilaria vermiculophylla against the diatom Stauroneis constricta and the filamentous alga Ceramium tenuicorne were assessed over one vegetation period on a monthly basis. We used two solvents with different polarities to extract chemical compounds from the alga. Both, hexane and dichloromethane (DCM) surface extracts, inhibited settlement of C. tenuicorne, while only hexane surface extracts deterred S. constricta. Furthermore, the activities of both extracts fluctuated on the scale of months and the fluctuations in the activity against C. tenuicorne, which were observed in DCM extracts, correlated with the intensity of fouling pressure that C. tenuicorne inflicted on G. vermiculophylla in the field. Thus, G. vermiculophylla appears to be able to adjust its antifouling defenses—at least partly—to fouling pressure.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00227-018-3365-4
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  • 5
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    Monitoring defensive responses in macroalgae – limitations and perspectives (2004)
    Springer
    In:  Phytochemistry Reviews, 3 (3). pp. 371-379.
    Details
    Publication Date: 2020-06-11
    Description: As part of an ongoing research program aiming at monitoring molecular changes in the tissues and metabolite trafficking in the hydrosphere of algae subjected to chemical stresses, we are discussing the various analytical techniques that have been employed to characterize, and sometimes to quantity these metabolites. High-field multinuclear and solid-state nuclear magnetic resonance (NMR) spectroscopies are powerful tools for metabolite characterization from extracts and in vivo, but quantification and kinetic aspects show some limitations. Modern MS (mass spectrometry) is extremely useful for fingerprinting samples against databases and when dealing with very low concentrations of metabolites, the limitations being set by the type of chromatographic separation and mode of detection coupled with the mass spectrometer. Regarding chemical communication, optimization in terms of resolution and efficiency of hydrosphere chemical analysis can theoretically be achieved in a system which integrates (i) a multiparametric incubation chamber, (ii) a gasphase or a liquid-phase separation system and (iii) mass spectrometer(s) equipped with one or two detectors responding to the analytical and quantitative needs. This text reviews some of the techniques that have been employed in various types of plant metabolic studies, which may serve as a basis towards an integrative analytical strategy directly applicable to the metabolomics of selected marine macrophytes.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s11101-005-1459-3
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    The Chondrus crispus-Acrochaete operculata host-pathogen association, a novel model in glycobiology and applied phycopathology (2001)
    Springer
    In:  Journal of Applied Phycology, 13 (2). pp. 185-193.
    Details
    Publication Date: 2014-01-29
    Description: A review is presented of ongoing research on the oligosaccharide signals involved in cell-cell recognition in the Chondrus crispus-Acrochaete operculata host-pathogen association. In this pathosystem, the host gametophytes are resistant to the pathogen, whereas the sporophytic generation is susceptible to infection. The virulence of the green algal pathogen is mediated by the recognition of carrageenan oligosaccharides released from its red algal host: kappa-carrageenan oligosaccharides inhibit A. operculata virulence while lambda carrageenan oligosaccharides enhance its pathogenicity. It appears that the recognition of A. operculata by C. crispus also involves an oligosaccharidic signal. This signal is present in the non-virulent form of the pathogen whereas it is absent from the virulent form. Altogether this pathosystem offers a unique model to investigate the recognition of oligosaccharide signals in plant-pathogen interactions. The possible applications of this research to develop new strategies for disease control in maricultured algal crops are discussed.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1023/A:1011164031386
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  • 7
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    Gracilaria and its epiphytes: 4. The response of two Gracilaria species to Ulva lactuca in a bacteria-limited environment (2001)
    Springer
    In:  Journal of Applied Phycology, 13 (6). pp. 501-507.
    Details
    Publication Date: 2014-01-29
    Description: The responses of Gracilaria lemaneiformis, an easily epiphytized host, and the relatively resistant G. cornea mutant, to the green alga Ulva lactuca were studied using biculture experiments with and without antibiotics. Both Gracilaria species grown with and without U. lactuca showed different levels of growth rate, release of hydrogen peroxide and of halogenated hydrocarbons. These quantitative differences led to a successful response against Ulva lactuca in the case of G. cornea mutant and to a failure in response in the case of G. lemaneiformis. The response of each Gracilaria species to U. lactuca was qualitatively similar to its response to bacteria. This suggests the involvement of oligosaccharide elicitors produced in the presence of epiphytes and bacteria. A clear Gracilaria inhibition was demonstrated with extracts of the culture medium. It appears that hydrogen peroxide, halogenated hydrocarbons and oligosaccharides may be components of the inhibitory activity of the extracts. The responses of Gracilaria species to the presence of U. lactuca suggest the characterization of a defence response.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1023/A:1012593400901
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  • 8
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    Bacterial induction and inhibition of a fast necrotic response in Gracilaria conferta (Rhodophyta) (1997)
    Springer
    In:  Journal of Applied Phycology, 9 (3). pp. 277-285.
    Details
    Publication Date: 2018-06-01
    Description: Of 45 bacterial isolates from healthy tips of Gracilaria conferta (Schousboe ex Montagne) J. et G. Feldmann, 29% were identified as 'conditional inducers' of an apical necrosis. That is, the isolates induced necrotic tips in G. conferta within 16 h after elimination of most of the resident microflora from the alga. Several disinfectants and antibiotics were screened for their ability to induce algal susceptibility to the bacteria and to suppress uncontrolled appearance of tip necrosis. Treatment with 100 mg L-1 Cefotaxim + 100 mg L-1 Vancomycin over three days was the least damaging and most efficient. Tip necrosis was related to isolates of the Corynebacterium-Arthrobacter-group and to the Flavobacterium-Cytophaga-group. The damaging effect occurred due to the bacterial excretion of active agents and was not correlated with a capability to degrade agar. The damaging influence of four Cytophaga-like strains was inhibited by 20 of 40 isolates. This protective effect was caused by very different organisms. In five of six cases examined further, the effect was not cellbound, but due to the excretion of agents. These were not antimicrobially active, but inactivated necrosis-inducing excretions. These results indicate that epiphytic bacterial degradation or inactivation of damaging agents is a protecting factor in Gracilaria, which prevents the alga from being harmed by epiphytes.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1023/A:1007990712925
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 9
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    Endogenous and exogenous elicitors of a hypersensitive response in Gracilaria conferta (Rhodophyta) (2000)
    Springer
    In:  Journal of Applied Phycology, 12 (2). pp. 139-145.
    Details
    Publication Date: 2014-01-29
    Description: Certain forms of oligocellulose and certainbacterially excreted peptides were identified asendogenous and exogenous elicitors, respectively, ofa tip bleaching response in Gracilaria conferta(Schousboe ex Montagne) J. et G. Feldmann. Thehalf-maximal tip bleaching response was observed when31.1 μM cellobiose or 11.6 μM cellotetraosewere present in the growth medium. In contrast, noresponse was detected after exposure to glucose,cellotriose, cellopentaose or maltooligosaccharides.The response was thus strongly dependent on themolecular size of the oligocellulose and onlysaccharides that consisted of an even number ofglucose residues were elicitor-active. Three bacterialspecies that had earlier been identified as potentialinducers of the tip bleaching symptom excretedelicitor-active compounds into the growth medium.These compounds were protease-sensitive and thuspeptides or proteins. The tip bleaching-inducingcompound that was excreted by one Cytophaga-likeorganism was partially purified. It could be extractedfrom culture supernatants with chloroform and itsmolecular size was between 700 and 1500 Da,corresponding with a structure of 4–20 amino acids.Various endogenous and exogenous elicitors are thusrecognized by G. conferta and allow this alga torespond hypersensitively to the maceration of its cellwall skeleton or just to the presence of certainepiphytic organisms
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1023/A:1008119125911
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
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    Selection of heat-shock resistance traits during the invasion of the seaweed Gracilaria vermiculophylla (2016)
    Springer
    In:  Marine Biology, 163 (5). Article Nr. 104.
    Details
    Publication Date: 2019-02-01
    Description: Most macroalgae and other aquatic organisms feature life cycles without a stage of dormancy and elevated stress resistance that is comparable to plant seeds. During anthropogenic transportation, they are therefore probably more exposed to stress than plant invaders, which could result in a more rigorous selection of stress-resistant phenotypes. However, selection of stress resistance during invasion processes of aquatic organisms has rarely been studied. We therefore compared the responses of native and non-native populations of the seaweed Gracilaria vermiculophylla to heat shock in common garden-type experiments. Specimens from six native populations in East Asia and from eight non-native populations in Europe and on the Mexican Pacific coast were acclimated to two sets of identical conditions before their resistance to heat shock was examined. The experiments were carried out twice—one time in the native range in Qingdao, China, and one time in the invaded range in Kiel, Germany—to rule out effects of specific local conditions. In both testing sites the non-native populations survived heat shock significantly better than the native populations. After three hours of heat shock G. vermiculophylla exhibited increased levels of heat-shock protein 70 (HSP70) and of a specific isoform of haloperoxidase, suggesting that both enzymes could be required for heat-shock stress management. However, the elevated resistance toward heat shock of non-native populations only correlated with an increased constitutive expression of heat-shock protein 70 (HSP70). The haloperoxidase isoform was more prominent in native populations, suggesting that not only increased HSP70 expression, but also reduced allocation into haloperoxidase expression after heat shock was selected during the invasion history. This selection probably happened early because the same combination of traits was detected in all realms within the non-native range.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00227-016-2881-3
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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