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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 5 (1992), S. 8-12 
    ISSN: 1432-2145
    Keywords: Glycoprotein ; Sexual inducer ; Volvox carteri
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Sexual inducer pheromones fromVolvox carten f.weismannia, strains 65–30(12) and 1B were purified and characterized as glycoproteins with apparent molecular weights of 27 kDa and 28.5 kDa, respectively. This subspecies yielded 20–40 times more pheromone based on weight per spheroid thanVolvox carteri f.nagariensis, but its specific activity (threshold dilution) is four to five orders of magnitude less (10−12 to 10−13 M). Gaschromatographic sugar analysis revealed quantitative differences in the composition of theO- andN-glucans compared with theV. carteri f.nagariensis inducer. TheV. carteri f.weismannia pheromones showed antigenic cross-reaction with an antiserum directed against chemically deglycosylated inducer fromV. carteri f.nagariensis. However, there is only unilateral biological cross-induction. TheV. carteri f.nagariensis inducer is strictly competent for its own gonidia only; the inducers fromV. carteri f.weismannia also cross-induceV. carteri f.nagariensis. This pattern of cross-induction suggests the existence of related pheromone receptors but with different ligand specificities.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 21 (1982), S. 643-653 
    ISSN: 0570-0833
    Keywords: Signal substances ; Brown algae ; Algae ; Pheromones ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Attraction and repulsion are responses to chemical stimuli which can be received and processed even by unicellular organisms without a morphologically defined nervous system. Chemical substances trigger off a chain of events which starts with a membrane-bound signal receptor and, after a sequence of regulatory and modulatory steps, ends in the modulation of a motor effector organ. Binding of the signal substances to the receptor produces conformational changes in which the receptor subunits are mutually dependent on one another, and also leads to chemical modification of the subunits and affects their molecular activity. These interactions, together with the characteristic type of movement, result in a physiological pattern of behavior which enables the flagellated sex cells (gametes) of marine brown algae to finally locate their partners. The simple but highly specific brown algae gamete systems have been investigated structurally and their biological activity analyzed. The signal substances are mainly highly unsaturated aliphatic or cyclic hydrocarbons with unsaturated side chains (general formula e. g. C11H14, C11H16, C11H18). These systems also serve as a simplifying model which helps in the understanding of complex ganglionic pathways in higher living organisms where the sense organs convey information from the surroundings to the central nervous system through nerve pathways. The information is then processed and answered, via efferent pathways, as movement.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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