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  • 1
    Electronic Resource
    Electronic Resource
    Quantitative determination of hydroxamic acids (1981)
    s.l. : American Chemical Society
    Analytical chemistry 53 (1981), S. 841-844 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00229a023
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  • 2
    Electronic Resource
    Electronic Resource
    Feeding deterrence properties of apo-fucoxanthinoids from marine diatoms. II. Physiology of production of apo-fucoxanthinoids by the marine diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana, and their feeding deterrent effects on the copepod Tigriopus californicus (1995)
    Springer
    Marine biology 124 (1995), S. 473-481 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The marine diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana have been shown to produce apo-fucoxanthinoid compounds which act as feeding deterrents against the harpacticoid copepod Tigriopus californicus. The amounts and types of apo-fucoxanthinoids produced were species specific. Th. pseudonana produced small quantities of apo-12′-fucoxanthinal and apo-13′-fucoxanthinone only during senescence, while P. tricornutum produced much greater quantities of these two compounds during both log and senescence phases, in addition to producing a third compound, apo-10-fucoxanthinal, only during senescence. For both species, production of apo-fucoxanthinoids increased as the cells entered senescence phase due to phosphate limitation. The amounts of apo-fucoxanthinoids necessary to reduce feeding in T. californicus by 50% ranged from 2.22 to 20.2 ppm. This range was approximately 1000 times lower than the total apo-fucoxanthinoid concentration in P. tricornutum. The amounts of apo-fucoxanthinoids necessary to cause a 50% mortality in a population of T. californicus ranged from 36.8 to 76.7 ppm. Thus, these compounds are present in concentrations which may have ecological significance in the control of bloom formation and grazing. The production of apo-fucoxanthinoids may be a phenomenon common to many diatoms, particularly as they enter senescence due to nutrient limitation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00363922
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  • 3
    Electronic Resource
    Electronic Resource
    Feeding deterrent and toxicity effects of apo-fucoxanthinoids and phycotoxins on a marine copepod (Tigriopus californicus) (1997)
    Springer
    Marine biology 128 (1997), S. 273-280 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using the marine harpacticoid copepod Tigriopus californicus, the effects of phytoplankton feeding deterrents and toxins were differentiated and measured. Eight compounds were tested for feeding deterrence and toxicity responses: four apo-fucoxanthinoids (apo-10′-fucoxanthinal, apo-12′-fucoxanthinal, apo-12-fucoxanthinal, and apo-13′-fucoxanthinone) and four well-known phycotoxins (domoic acid, okadaic acid, microcystin-LR, and a mixture of PSP-1 toxins). Since several of these compounds exhibited both feeding deterrence and toxicity, a model was developed to deconvolute the observed toxicity response from the observed feeding deterrence response, and to classify these compounds based on the degree of toxicity and/or feeding deterrence they exhibited towards T. californicus. Microcystin-LR, the PSP-1 toxins, and the four apo-fucoxanthinoids behaved only as feeding deterrents at low concentrations. Okadaic acid exhibited both toxicity and feeding deterrence at low concentrations, with the threshold concentration for feeding deterrence at a lower level than the threshold concentration for toxicity. Domoic acid acted only as a toxin at low concentrations, with all decreases in feeding resulting from the death of the copepod.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050092
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  • 4
    Electronic Resource
    Electronic Resource
    Feeding deterrence properties of apo-fucoxanthinoids from marine diatoms. I. Chemical structures of apo-fucoxanthinoids produced by Phaeodactylum tricornutum (1995)
    Springer
    Marine biology 124 (1995), S. 467-472 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Methanol extracts of freshly harvested cells of the marine diatom Phaeodactylum tricornutum were found to produce a feeding deterrent effect in the copepod Tigriopus californicus. Bioassay guided fractionation of the methanol extracts led to the isolation of four compounds possessing feeding deterrent activity. The compounds were identified as apo-10′-fucoxanthinal (1), apo-12′-fucoxanthinal (2), apo-12-fucoxanthinal (3), and apo-13′-fucoxanthinone (4) by detailed spectroscopic analysis and comparison with authentic compounds produced semi-synthetically from fucoxanthin. Compounds 1 to 4 exhibited feeding deterrent responses in T. californicus at concentrations of less than 20 ppm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00363921
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  • 5
    Electronic Resource
    Electronic Resource
    Algal plating as a tool for investigating allelopathy among marine microalgae (1980)
    Springer
    Marine biology 59 (1980), S. 7-13 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chemical interactions among marine microalgae were studied in cultures of pennate diatoms on agar plates. Nine marine and freshwater pennate diatoms were surveyed as potential bioassay organisms; Cylindrotheca fusiformis was most favourable for assays because of its rapid and even growth on agar. Diatom and bacterial bioassays were used to screen cell and filtrate extracts of 14 microalgal cultures. A number of these algal species, which were grown axenically, produced extractable, intracellular and/or extracellular substances that inhibited the growth of C. fusiformis. Our results suggest that the culturing of pennate diatoms on a solid medium can provide a simple bioassay for screening algal extracts which potentially contain growth inhibitors involved in microalgal allelopathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396977
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  • 6
    Electronic Resource
    Electronic Resource
    Autotoxic antibiotic production by a marine Chromobacterium (1974)
    Springer
    Marine biology 27 (1974), S. 281-285 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An antibiotic-producing Chromobacter was isolated from a sea-water sample from the North Pacific Gyre. The bacterium produces 3 bromine-containing metabolites: tetrabromopyrrole, 2-(2′-hydroxy-3′, 5′-dibromophenyl)-3, 4, 5-tribromopyrrole, and hexabromo-2, 2′-bipyrrole. It also synthesizes n-propyl 4-hydroxybenzoate and 4-hydroxybenzaldehyde. Some of these compounds were shown to be responsible for autoinhibition of the Chromobacterium itself, as well as for antibiotic action against other kinds of bacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394363
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  • 7
    Electronic Resource
    Electronic Resource
    Evaluation of the copepod Tigriopus californicus as a bioassay organism for the detection of chemical feeding deterrents produced by marine phytoplankton (1994)
    Springer
    Marine biology 121 (1994), S. 89-95 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Marine phytoplankton have been shown to use chemical feeding deterrents to reduce or inhibit zooplankton grazing. In order to screen phytoplankton species for feeding deterrent production and to isolate and identify feeding deterrent compounds, a new, rapid, and reliable laboratory bioassay was developed. This bioassay used the laboratory-reared harpacticoid copepod Tigriopus californicus and measured inhibition of feeding by measuring the fecal pellet production rate. The bioassay was capable of detecting deterrent compounds: (1) adsorbed onto ground fish food (a normally palatable food); (2) dissolved in a mixture of seawater and live Thalassiosira pseudonana cells (a species of diatom which had no feeding deterrent activity); and (3) present in live cell cultures. Method (2) was recommended for use in bioassay-guided fractionation (isolation of chemical compounds), as it was reliable, rapid, accurate, and easy to perform with large numbers of samples. The total bioassay time was 〈 48 h, and data collection required only a microscope. Methanolic cell extracts of several phytoplankton species were screened for feeding deterrent activity. Extracts from the diatom Phaeodactylum tricornutum and the dinoflagellate Gonyaulax grindleyi gave feeding deterrent responses, while extracts from the diatom Thalassiosira pseudonana gave no feeding deterrent responses. Live P. tricornutum cells deterred feeding at densities of 6x105 cells ml-1. This bioassay should provide a valuable tool in screening phytoplankton for feeding deterrent compounds and determining the chemical nature of these compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349477
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  • 8
    Electronic Resource
    Electronic Resource
    Examination of hydroxamate-siderophore production by neritic eukaryotic marine phytoplankton (1983)
    Springer
    Marine biology 75 (1983), S. 9-17 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Species of neritic eukaryotic marine phytoplankton were investigated during 1982 for hydroxamate-type siderophore production under iron-sufficient and iron-deficient culture conditions. Three of the 5 Prorocentrum species examined produced siderophores. Prorocentrin, the extracellular hydroxamate-type siderophore isolated from P. minimum, was also produced by P. mariae-lebouriae and P. gracile. P. maximum and P. micans grew poorly in iron-deficient medium and did not produce intracellular or extracellular hydroxamate-type siderophores. Thalassiosira pseudonana and Dunaliella tertiolecta produced extracellular siderophores under iron-deficient conditions, but siderophore production was not detected in the other two species, Skeletonema costatum and Olisthodiscus luteus. Each species which produced extracellular Csaky-positive hydroxamate showed a similar pattern of production. Under iron-sufficient conditions there was no measurable siderophore found either intracellularly or extracellularly. Under iron-deficient culture conditions hydroxamate-type siderophore was produced 1 to 2 d after the cessation of growth in the stationary phase. Production was over a short period of time (1 to 2 d) and the siderophore did not remain in the medium. The rate of siderophore disappearance from the medium was similar to the rate of production. Each species which produced siderophores showed an increase in in vivo fluorescence coincidental with the disappearance of the extracellular siderophore from the culture medium. There was no corresponding increase in in vivo fluorescence in iron-sufficient cultures. It is suggested that in vivo fluorescence may be used as a screening procedure for determining hydroxamate-type siderophore production in eukaryotic phytoplankton. An hypothesis on the iron uptake mechanism is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392625
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  • 9
    Electronic Resource
    Electronic Resource
    Use of high-performance liquid chromatography to investigate the production of paralytic shellfish toxins by Protogonyaulax spp. in culture (1986)
    Springer
    Marine biology 93 (1986), S. 361-369 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Procedures have been developed for the extraction and high-performance liquid chromatography (HPLC) analysis of paralytic shellfish poisoning (PSP) toxins from Protogonyaulax spp. grown in batch culture. Using these procedures, the toxin content of two isolates of P. tamarensis (NEPCC 183 and 255) and one isolate of P. catenella (NEPCC 355) were examined. Total toxin and individual toxin concentrations were measured for each isolate during the exponential and stationary phases of growth in batch culture. The total toxicity of each isolate as measured by HPLC analysis was found to agree with toxicity as determined by the standard mouse bioassay. Two of the isolates (255 and 355) were found to be toxic and the third (183) was non-toxic. The toxic isolates (255 and 355) both showed higher average total PSP toxin content during the exponential phase (35 and 23 fmol toxin cell-1, respectively) than during the stationary phase (21 and 8 fmol toxin cell-1, respectively). These cultures differed dramatically in their toxin composition. P. tamarensis (255) contained a large proportion of the N(21) sulfo toxins (B1, B2, C1, C2) while P. catenella (355) contained primarily Gonyautoxins 1 through 4. The percent composition of individual toxins was found to be constant throughout the growth cycle for both toxic isolates, even though the total toxin concentration varied. Our results suggest that PSP toxin profiles might be useful as chemotaxonomic indicators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00401103
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  • 10
    Electronic Resource
    Electronic Resource
    Isolation of various forms of sterol β-d-glucoside from the seed of Cycas circinalis: neurotoxicity and implications for ALS-parkinsonism dementia complex (2002)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 82 (2002), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The factors responsible for ALS-parkinsonism dementia complex (ALS-PDC), the unique neurological disorder of Guam, remain unresolved, but identification of causal factors could lead to clues for related neurodegenerative disorders elsewhere. Earlier studies focused on the consumption and toxicity of the seed of Cycas circinalis, a traditional staple of the indigenous diet, but found no convincing evidence for toxin-linked neurodegeneration. We have reassessed the issue in a series of in vitro bioassays designed to isolate non-water soluble compounds from washed cycad flour and have identified three sterol β-d-glucosides as potential neurotoxins. These compounds give depolarizing field potentials in cortical slices, induce alterations in the activity of specific protein kinases, and cause release of glutamate. They are also highly toxic, leading to release of lactate dehydrogenase (LDH). Theaglycone form, however, is non-toxic. NMDA receptor antagonists block the actions of the sterol glucosides, but do not compete for binding to the NMDA receptor. The most probable mechanism leading to cell death may involve glutamate neuro/excitotoxicity. Mice fed cycad seed flour containing the isolated sterol glucosides show behavioral and neuropathological outcomes, including increased TdT-mediated biotin–dUTP nick-end labelling (TUNEL) positivity in various CNS regions. Astrocytes in culture showed increased caspase-3 labeling after exposure to sterol glucosides. The present results support the hypothesis that cycad consumption may be an important factor in the etiology of ALS-PDC and further suggest that some sterol glucosides may be involved in other neurodegenerative disorders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2002.00976.x
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