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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 96 (1992), S. 0 
    ISSN: 1574-6968
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Abstract The bacterium Sphingomonas sp. SS31, which was obtained from the diphenyl ether-degrading strain Sphingomonas sp. SS3 by an adaptation process, utilized 3-methyldiphenyl ether for growth in addition to diphenyl ether. The initial enzymatic attack onto this compound proceeded by a regioselective, but non-specific dioxygenation at the carbon carrying the ether bridge and the adjacent carbon of the unsubstituted as well as the methyl-substituted aromatic nucleus. Upon spontaneous decomposition, the resulting unstable hemiacetal structure yielded 3-methylphenol and catechol, or phenol, 3-methylcatechol, and 4-methylcatechol, respectively. Phenol and 3-methylphenol methylphenol were oxidized to the corresponding catechols which, after subsequent ortho-cleavage, were channeled into the oxoadipate pathway. Minor amounts of 3-(hydroxymethyl)-diphenyl ether detected in the supernatant of the culture broth gave evidence for an unproductive oxidation of the side-chain, finally leading to the nondegradble product 3-carboxydiphenyl ether.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1072-8368
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Medizin
    Notizen: [Auszug] Sir—Grb2 is a 25,000 Mr ‘adaptor’ protein comprising one SH2 and two SH3 domains1,2. It is found in the cytoplasm of cells in complex with the Son of sevenless (Sos) protein. The complex is formed through the interaction of the Grb2 SH3 domains with the proline-rich region of ...
    Materialart: Digitale Medien
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  • 3
    ISSN: 1573-1561
    Schlagwort(e): Ophrys sphegodes subsp sphegodes ; Andrena nigroaenea ; floral scent ; floral semiochemicals ; headspace sorption ; postpollination changes ; nocturnal scent emission
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract We investigated the scent composition of individual flowers of Ophrys sphegodes, its alteration following pollination, and of picked flowers by day and at night. Odor samples were collected by headspace sorption and analyzed by gas chromatography and mass spectrometry. To evaluate the function of postpollination odor changes, we carried out behavioral tests on the pollinator Andrena nigroaenea with pollinated and unpollinated flowers. We identified 27 volatiles in the flower scents. Aldehydes and alkanes were most frequently found. Aldehydes were the most abundant class of compounds (40–50%). When flowers were picked, they emitted significantly lower total amounts of volatiles than unpicked flowers, and their odor bouquets were significantly different. Comparison of scents released by day and at night showed no decrease in scent emission during nighttime, but the odor bouquets were significantly different. Pollinated flowers produced significantly different odor bouquets, and the total amount of scent emitted two to four days after pollination was significantly lower compared with unpollinated flowers. In addition, behavioral tests with A. nigroaenea males showed that flowers were significantly less attractive three days after pollination. This reduced attractiveness is hypothesized to guide pollinators to the unpollinated flowers within an inflorescence, and thus increase the reproductive success of the plant.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1573-1561
    Schlagwort(e): Hymenoptera ; Eulophidae ; Diglyphus isaea ; courtship behavior ; contact pheromones
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The sexual behavior of the ectoparasitoidDiglyphus isaea is described. Recognition of the female by the male occurs at close range. Males initiate courtship behavior in the presence of a living female regardless of age, as well as in the presence of a female killed by freezing. Courtship behavior is not observed in the presence of a dead female washed with organic solvents but could be elicited using a lure covered with a female organic extract. These findings demonstrate that each sex develops a specific chemical signature that can be dissolved in hexane and transferred to a lure. Analysis of organic extracts by gas chromatography revealed chemical dimorphism between the two sexes. Gas chromatography coupled with mass spectrometry showed that the main components in females were esters of medium-chain fatty acids and long-chain 11-alcohols. There were few hydrocarbons. Female esters, which were present in only small proportions in males, were recovered in the nonhydrocarbon fraction obtained after fractionation of the total extract on a silica-filled microcolumn as a mixture containing 11-heneicosyl, 11-docosyl, 11-tricosyl, 11-tetracosyl, and 11-pentacosyl octanoate, and 11-docosyl, 11-tricosyl, 11-tetracosyl, and 11-pentacosyl decanoate. These results demonstrate that there is a specific gender-related chemical signature.
    Materialart: Digitale Medien
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