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  • 1
    Electronic Resource
    Electronic Resource
    Chemical aspects of mass spawning in corals. I. Sperm-attractant molecules in the eggs of the scleractinian coral Montipora digitata (1994)
    Springer
    Marine biology 118 (1994), S. 177-182 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper provides the first evidence for sperm chemotaxis in the Scleractinia. Montipora digitata Dana, 1845 (Scleractinia: Coelenterata) is a hermaphroditic coral which reproduces bi-annually, releasing egg-sperm bundles during the mass spawning at Magnetic Island (19°10′S; 146°52′E) in late spring-early summer, and autumn each year. The buoyant egg-sperm bundles float to the surface where they break apart, releasing eggs and sperm into the ocean. Fertilisation occurs after ∼30 min. Unfertilized eggs were collected, washed free of sperm, and freeze-dried. The eggs were extracted with dichloromethane, fractionated by chromatography on silica gel, and the fractions assayed for their ability to attract M. digitata sperm. The active fraction was further fractionated by high-performance liquid chromatography, resulting in the isolation of three highly unsaturated fatty alcohols: (1) dodeca-2,4-diynol; (2) tetradec-13-ene-2,4-diynol; (3) (14Z)-heptadeca-14,16-diene-2,4-diynol. Of these three compounds, only Compound 1 attracted sperm of M. digitata. Synthetic Compound 1, produced from simple precursors by known reactions, possessed sperm-attracting activity comparable to the naturally derived attractant. Preliminary experiments suggest that the natural mixture of Compounds 1, 2 and 3 in the ratio 1:4:9 is more effective in attracting sperm from M. digitata than sperm from other Montipora species. Sperm attractants may act to reduce the incidence of hybridisation between different species of Montipora.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349783
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  • 2
    Electronic Resource
    Electronic Resource
    Lack of avoidance of phenolic-rich brown algae by tropical herbivorous fishes (1991)
    Springer
    Marine biology 109 (1991), S. 335-343 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract High levels of polyphloroglucinol phenolics in marine brown algae are usually interpreted as a defensive response to herbivory. However, tropical brown algae generally contain very low levels of phenolics, even though herbivory in many tropical systems (e.g. coral reefs) is intense. This apparent paradox would be explained if polyphenolics did not deter tropical herbivores, in which case selection by herbivores for high levels of phenolics in tropical algae would be weak. To examine this hypothesis, in February 1989 we presented mixed assemblages of herbivorous fishes on the Great Barrier Reef with tropical, phenolic-poor brown algae (primarilySargassum spp.) and closely related (conspecifics in one instance) phenolic-rich temperate species. Different species of brown algae were eaten at very different rates, but these differences were not correlated with variation in the phenolic levels among the plants. TLC and NMR analyses showed no evidence of other, non-polar, metabolites in these algae, with the exception of the temperate speciesHomoeostrichus sinclairii. Thus, variation in non-polar metabolites also did not explain the differences in susceptibility to herbivores among these algae. We conclude that the herbivorous fishes studied here were not deterred by phenolic-rich algae, which suggests that levels of phenolics in many tropical algae may generally be low due to their ineffectiveness as defences. However, alternative explanations for the pattern are possible, and these are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01319401
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  • 3
    Electronic Resource
    Electronic Resource
    Chemical aspects of mass spawning in corals. II. (-)-Epi-thunbergol, the sperm attractant in the eggs of the soft coral Lobophytum crassum (Cnidaria: Octocorallia) (1995)
    Springer
    Marine biology 123 (1995), S. 137-143 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The eggs of Lobophytum crassum Von Marenzeller, 1886, collected at Magnetic Island (19°10′S; 146°52′E) in October or November between 1983 and 1993, contained significant amounts (6% dry weight) of (-)-epi-thunbergol, in addition to other terpenoid metabolites also present in the parent colony. (-)-Epi-thunbergol was not present in the tissues of the releasing colony. Using fluorocarbon droplets impregnated with the chemotactic molecules and a videomicroscopic technique for the direct observation of sperm under the influence of attractant molecules, we showed that (-)-epi-thunbergol, whether isolated from L. crassum or from a gorgonian octocoral (Briareum sp.), significantly attracts sperm from L. crassum colonies. Attraction could be detected using direct observation at concentrations as low as 3.25 μg ml-1. This is the first evidence for sperm chemotaxis in the Alcyonacea. Eggs from L compactum, a common alcyonacean coral at Orpheus Island (18°36′S; 146°29′E) contained (-)-thunbergol as the egg-specific compound. L. compactum was not found at Magnetic Island. (-)-Thunbergol from L. compactum and (+)-thunbergol from a Douglas fir tree both showed levels of attraction similar to (-)-epi-thunbergol against L. crassum sperm. Although L. crassum sperm were apparently neither stereo- nor enantio-specific in their selectivity for chemotactic molecules, (-)-epi-thunbergol was identified as the natural sperm attractant in the eggs of L. crassum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350332
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  • 4
    Electronic Resource
    Electronic Resource
    Chemically mediated interactions between the red algaPlocamium hamatum (Rhodophyta) and the octocoralSinularia cruciata (Alcyonacea) (1991)
    Springer
    Marine biology 108 (1991), S. 315-320 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Interactions between the red algaPlocamium hamatum J. Agardh (Rhodophyta) and other benthic organisms including the alcyonacean soft coralSinularia cruciata (Tixier-Durivault) were investigated on an inshore fringing reef environment in whichP. hamatum was the dominant large fleshy alga. Field observations of sessile reef organisms including octocorals and sponges living in close proximity toP. hamatum revealed that varying degrees of tissue necrosis were suffered by the invertebrates when in physical contact with the alga. In order to establish whether the chemical constituents of the alga, especially chloromertensene, played a role in this necrosis, manipulative field experiments were carried out in the Pelorus Channel, Palm Island group (18°34′S; 146°29′E), North Queensland, Australia, in November and December 1988. The first experiment involved the relocation of healthy plants and soft corals into contact and non-contact situations on a mesh grid. In all cases of contact betweenP. hamatum andS. cruciata, the soft coral suffered tissue necrosis (n=6,p=0.0022). The second experiment had the same design, but involved the use of artificial “plants” both uncoated and coated with natural levels of chloromertensene, in contact withS. cruciata. In all cases of contact with coated treatments, necrosis was observed inS. cruciata (n=4,p=0.025). In cases where uncoated artificial fronds were placed in contact with soft corals,S. cruciata showed minor abrasion effects, but no appreciable necrosis. Coated treatments were not fouled by epiphytes during the experiment and were not consumed by predators. Uncoated treatments were rapidly reduced in size by predation and any remaining material was biofouled. These experiments thus demonstrated that the deleterious effects observed in soft corals in the field were caused by contact with the algaP. hamatum, that these effects were indeed chemically mediated by chloromertensene, and that physical contact without chemical intervention caused no such deleterious effects. This is the first experimental evidence which conclusively demonstrates allelopathy between an alga and other marine organisms and identifies the compound responsible for the observed allelopathic effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01344346
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  • 5
    Electronic Resource
    Electronic Resource
    Localisation and surface quantification of secondary metabolites in the red alga Delisea pulchra (1999)
    Springer
    Marine biology 133 (1999), S. 727-736 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The localisation of halogenated furanones, the biologically active secondary metabolites from the red alga Delisea pulchra (Greville), was determined by a combination of fluorescence microscopy, culture studies and quantitative chemical analyses. All types of evidence showed that furanones are localised in the central vesicle of gland cells in D. pulchra. These cells release furanones onto the surface of the plant, where they can be quantified using a newly developed surface extraction-technique. Levels of furanones on the surface of the plant were highest near the apical tips (≃100 ng cm−2), and decreased towards the base of the alga. Variation in furanone levels within the plant and variation in the number of gland cells followed a similar pattern. The localisation of furanones within gland cells in D. pulchra and the presence and concentrations of furanones on the surface of the plant are consistent with furanones functioning as antifoulants and in mediating other ecological interactions at the surface of the alga.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050514
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  • 6
    Electronic Resource
    Electronic Resource
    A diterpene from the marine brown alga Dictyota bartayresii
    Amsterdam : Elsevier
    Phytochemistry 31 (1992), S. 2541-2542 
    Details
    ISSN: 0031-9422
    Keywords: 8β-hydroxypachydictyol A. ; Dictyota bartayresii, Dictyotaceae ; brown algae ; diterpenes
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0031-9422(92)83322-P
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  • 7
    Electronic Resource
    Electronic Resource
    New halogenated furanones from the marine alga delisea pulchra (cf. fimbriata)
    Amsterdam : Elsevier
    Tetrahedron 49 (1993), S. 11213-11220 
    Details
    ISSN: 0040-4020
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0040-4020(01)81808-1
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  • 8
    Electronic Resource
    Electronic Resource
    Two metabolites from the red alga Laurencia flexilis
    Amsterdam : Elsevier
    Phytochemistry 34 (1993), S. 725-728 
    Details
    ISSN: 0031-9422
    Keywords: Laurencia flexilis ; chamigrenes. ; lipids ; red alga
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0031-9422(93)85347-T
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  • 9
    Electronic Resource
    Electronic Resource
    Five new monoterpenes from the marine red alga Portieria hornemannii
    Amsterdam : Elsevier
    Tetrahedron 47 (1991), S. 5717-5724 
    Details
    ISSN: 0040-4020
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0040-4020(01)86524-8
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  • 10
    Electronic Resource
    Electronic Resource
    Dynamics of Algal Secondary Metabolites in Two Species of Sea Hare (2000)
    Springer
    Journal of chemical ecology 26 (2000), S. 721-744 
    Details
    ISSN: 1573-1561
    Keywords: Opisthobranchia ; Anaspidea ; Aplysia ; Delisea ; Laurencia ; algae ; sequester ; secondary metabolites ; accumulation ; excretion ; chemical defense
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The function of acquired algal secondary metabolites in sea hares is the subject of debate, in part because the dynamics/processing of metabolites by sea hares is poorly understood. This study investigates the dynamics of red algal secondary metabolites in two sea hares, Aplysia parvula and Aplysia dactylomela. Secondary metabolite levels were quantified for the dietary red algae Laurencia obtusa and Delisea pulchra and for sea hares collected from these seaweeds in the field. The patterns and dynamics of algal secondary metabolites were further investigated in the laboratory by quantitative analysis of secondary metabolites in sea hares grown on diets of L. obtusa, D. pulchra, or the green alga Ulva sp. Sea hares accumulated the most abundant metabolites from each red alga, the terpene palisadin A from L. obtusa, and the halogenated furanone 3 from D. pulchra, and stored a greater proportion of these metabolites than other algal metabolites. A. parvula accumulated D. pulchra metabolites at much higher levels than L. obtusa metabolites. A. dactylomela accumulated similar concentrations of L. obtusa metabolites to A. parvula. The loss of L. obtusa metabolites by A. dactylomela matched that expected for dilution of metabolites via growth of the sea hares. However, the loss of L. obtusa metabolites by A. parvula was faster than predicted for growth alone, suggesting that metabolites were actively metabolized or excreted. Data for the loss of D. pulchra metabolites by A. parvula was equivocal. The secretions of A. parvula fed D. pulchra or L. obtusa were analyzed for the presence of algal secondary metabolites to investigate one possible path of excretion. L. obtusa secondary metabolites were detected in the mucous and opaline secretions of A. parvula, but D. pulchra metabolites were not detected in any secretions. The deployment of L. obtusa secondary metabolites in secretions by A. parvula may explain the more rapid rate of loss of these compounds and is consistent with a possible defensive role for acquired metabolites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005484306931
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