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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of agricultural and food chemistry 40 (1992), S. 650-654 
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 65 (1987), S. 169-173 
    ISSN: 1432-1440
    Keywords: Gastrin ; Insulin ; Omeprazole ; Somatostatin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The influence of a 4-week treatment with the substituted benzimidazole omeprazole (20 mg daily) or placebo on gastric endocrine function was tested in healthy male volunteers. Compared with placebo-treated subjects basal serum gastrin levels were slightly but significantly increased after treatment with omeprazole from 10 to 22 pg/ml (medians;P〈0.05) but returned to pretreatment values after 2 weeks recovery (9 pg/ml). Antral gastrin tissue concentration increased and was still elevated after recovery; however, antral gastrin concentrations also increased in placebo controls, and increments immediately after cessation of omeprazole treatment (2.58 µg/g; median) were not significantly over control values (1.92 µg/g;P〉0.1). Postprandial gastrin release, basal and food-stimulated insulin release, antral somatostatin concentration, and volume densities of antral G and D cells were unaffected. It is concluded that, due to incomplete inhibition of gastric acid secretion at the omeprazole dose studied, only slight effects on the endocrine stomach are to be expected after 4 weeks of administration of omeprazole.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The multiple defensive strategies of four Mediterranean ascoglossan molluscan species, belonging to two different Polybranchioidea families, Cyerce cristallina (Trinchese, 1881) and Caliphylla mediterranea (Costa A., 1869) (Polybranchiidae), and Ercolania funerea (Costa A., 1867) and Placida dendritica (Alder and Hancock, 1843) (Stiligeridae), were studied. E. funerea, P. dendritica and C. mediterranea were collected from the lake Fusaro (Arco Felice, Naples) in 1992. C. cristallina was collected from Capo Miseno (Bay of Naples) in 1991. C. cristallina and E. funerea easily undergo autotomy of dorso-lateral appendages (cerata) followed by an extraordinarily quick (8 to 10 d) regeneration of the latter. Histological analyses showed the presence, at the basis of both normal and regenerated cerata of these species, of a muscular sphincter which facilitates the autotomic process. C. mediterranea and P. dendritica, which do not undergo autotomy, lack this anatomical feature but feed upon algae belonging to the Chaetomorpha and Bryopsis genera, and, as shown by electron microscopy studies, retain large quantities of chloroplasts which they use as camouflage amidst algae and to escape predation. E. funerea also exploits this behavioral defense mechanism. Histological investigations also revealed in the cerata of all four species several multi-cellular mucous glands responsible for the secretion of the slime typical for these molluscs. C. cristallina, E. funerea and P. dendritica secrete large amounts of slime, whose extracts displayed ichthyotoxic activity when assayed by the Gambusia affinis ichthyotoxicity assay, while extracts of C. mediterranea slime were not toxic. A chemical analysis of the slime, mantle and cerata led to the isolation of polypropionate α- and γ-pyrones from all species except C. mediterranea. These secondary metabolites possess structures that differ only by the degree of methylation and the geometry of double bonds of the side chain and are specifically distributed in cerata and slime of C. cristallina and E. funerea. The pyrones also display different activities in the Hydra vulgaris regeneration assay and in the G. affinis ichthyotoxicity test and, depending on their structural features and tissue distribution, are likely to play a role either as defense allomones or as supportive inducers of cerata regeneration. In conclusion, combined biological observations and histological and chemical techniques generated valuable information on the defensive behavior of these four ascoglossan species which exploit various combinations of the same behavioral and/or chemical defensive strategies and thus successfully avoid predation.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 111 (1991), S. 353-358 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tethys fimbria is a poorly studied nudibranch that, recently, has been shown to possess large amounts of unusual prostaglandin (PG) derivatives. The cerata ofT. fimbria collected in the Bay of Naples (Italy) between November 1990 and January 1991 were submitted to histological analysis. This revealed the presence of both longitudinal and transverse smooth muscle fibres together with multicellular defensive glands, responsible for the typical spontaneous contractions of the cerata and for the extrusion of a hyaline secretion, respectively. A role forT. fimbria cerata in mollusc defense behaviour is suggested. Chemical analysis of the cerata led to the isolation of high levels of prostaglandin free acids (PGs) and of PG-1,15-lactones of the E, A and F series, whereas the secretion contained only PG-1,15-lactones of the E and A series. The latter were found to be toxic to mosquito fish at concentrations ranging between 1 and 10 µg ml−1, whereas PG free acids and PG-1,15-lactones of the F series were not toxic. The possibility that PGE- and PGA-1.15-lactones areT. fimbria defense allomones is discussed.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ascoglossan mollusc Elysia timida Risso, 1818 retains functional chloroplasts from its algal food, the chlorophycean Acetabularia acetabulum (L.). Photosynthates from the plastids are an important source of organic nutrients for the mollusc. Chloroplast exploitation has an ecological function, allowing the ascoglossan to live entirely on an algal diet which is of limited, seasonal availability to other herbivores. Between October 1987 and July 1988, the annual evolution of the molluscan and algal populations was studied in a cove of Mazarrón Bay, southeast Spain. The population density of the mollusc is highly dependent on its food supply, being controlled by the seasonal life cycle of the algal population. During its life cycle, the degree of grazing by the mollusc decreases with increasing algal calcification, the cell walls of the alga progressively calcify, and the eventually highly calcificied stalks are completely resistant to ascoglossan grazing. In contrast, the exploitation of the algal chloroplasts retained by the molluscs increases during the seasonal cycle. The progressively increasing scarcity of food during the seasonal cycle may have led to the retention of symbiotic chloroplasts by E. timida. The developmental strategy of the ascoglossan also changes during the year: when food is abundant (in November, December, January, February and March) it is direct, with no planktonic larval phase, when food is scarce (in October, April, May and June) it is lecithotrophic, with a short planktonic larval phase. Chloroplast retention acts as a buffer, alleviating the effects of annual changes in density, structure and abundance of the alga on the nutritional state of the molluse.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The marine sponge Dysidea fragilis from El Mar Menor, a hypersaline coastal lagoon (Murcia, Spain), contains the furanosesquiterpenoid ent-furodysinin as the major secondary metabolite. D. fragilis emits a defensive white fluid when it is disturbed. Electron micrographs of this fluid revealed intact vesiculated cells together with other amorphous material. Dissociated cells are more rounded in shape but maintain the same ultrastructural features as cells observed in ultra-thin sections of the whole sponge. The defensive secretion is composed mainly of sponge cells with abundant light vesicles. Sometimes these light vesicles appear to open into the intercellular space; this correlates with surface blebs on these cells observed under scanning electron microscopy. The intracellular location of ent-furodysinin was confirmed by Erlich staining. In laboratory assays, we examined the role of ent-furodysinin as a feeding deterrent to generalist fish predators. It was isolated from D. fragilis and incorporated into a carrageenan-based artificial diet. The addition of ent-furodysinin to the artificial diet reduced feeding by the fish Thalassoma pavo. Similarly, fish did not feed on artificial diet above which defensive secretion of D. fragilis had been ejected with a small syringe.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1432
    Keywords: Human genome ; Dinucleotides ; Introns ; II-III codon positions ; G + C content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have studied the behavior of the dinucleotide preferences under G + C content variation in human genes. The doublet preferences for each dinucleotide were compared between two functionally distinct zones in genes, the II-III codon positions, and the introns. The 16 dinucleotides have been tentatively classified in three groups: AA, AC, CC, CT, and GA, doublets showing no difference between introns and II-III codon positions in the full range of G + C variation TG and TA, which differ in the full range of G + C variation AT, AG, GT, TC, TT, GG, GC, CG, and CA, which show differences in regions over 50% G + C A remarkable pattern observed concerns the behavior of GG, GC, and TC, which showed opposite trends in II-III codon positions and in introns. If codon positions and introns are under the same structural requirements and the same mutational bias, our results indicate that the differences observed could be related to post-transcriptional constraints acting on mRNA.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0927-6505
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0550-3213
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Comparative Biochemistry and Physiology -- Part B: Biochemistry and 108 (1994), S. 107-115 
    ISSN: 0305-0491
    Keywords: Bosellia mimetica ; Diterpenoids ; Elysia translucens ; Elysia viridis ; Polypropionates ; Sacoglossans
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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