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  • 1
    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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  • 2
    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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  • 3
    Electronic Resource
    Electronic Resource
    Hemiasterlin Methyl Ester (1996)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 1525-1527 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270195016556
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  • 4
    Electronic Resource
    Electronic Resource
    Degraded monoterpenes from the opisthobranch molluscMelibe leonina (1983)
    Springer
    Cellular and molecular life sciences 39 (1983), S. 255-256 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 2,6-dimethyl-5-heptenal (1) and 2,6-dimethyl-5-heptonic acid (2) were isolated from skin extracts of the nudibranchMelibe leonina. The aldehyde1 is responsible for the pleasant odour of the animals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01955289
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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
    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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  • 7
    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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  • 8
    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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  • 9
    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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  • 10
    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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