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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 9 (1988), S. 323-337 
    ISSN: 0739-4462
    Keywords: oocytes ; follicle cells ; vitellogenin ; receptors ; calcium ; calcium ionophore ; calcium chelator ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Two classes of vitellogenin binding sites with Kd-values of 7.3 nM and 290 nM were observed in follicle-membrane preparations of the cockroach Nauphoeta cinerea using a membrane-binding assay at pH 8. Separation of follicle cells and basal laminae from oocyte membranes prior to binding studies showed that the fraction consisting of follicle cells and basal laminae (FC/BL) contained high-affinity binding sites for vitellogenin (Kd=16.6 nM), whereas loweraffinity binding sites (Kd=200 nM) were found in the oocyte membrane fraction. The concentration of Ca2+ had a distinct effect on vitellogenin binding and uptake: maximal binding to the oocyte membrane fraction was observed at 0.3 mM Ca2+ and to the FC/BL fraction at 10 mM, whereas uptake of vitellogenin by oocytes in vitro was highest at 4 mM Ca2+. The calcium ionophore A23187 decreased vitellogenin uptake. This effect of A23187 could be counteracted by the calcium chelator Quin2. A hypothetical model for the uptake of vitellogenin into follicles of Nauphoeta cinerea is suggested.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 13 (1990), S. 117-125 
    ISSN: 0739-4462
    Keywords: arylphorin ; Trichoplusia ni ; Chelonus ; parasitoid ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Arlyphorin (Ap) is the principal protein of the last larval instar hemolymph of Trichoplusia ni. It was shown to be homologous with the Aps of Manduca sexta and Lymantria dispar by Western blot and quantitative immunoelectrophoresis. Another hemolymph storage protein in T. ni of lesser titer was shown to be homologous with larval hemolymph protein (LSP) of M. sexta. Ap titer increased dramatically in the last larval instar of T. ni, as in other holometabolous insects studied. Parasitization by Chelonus sp. caused the Ap titer to rise prematurely in the penultimate larval instar of T. ni. This rise in Ap in the fourth instar is one of the earliest diagnostic signs of parasitization. Among the suite of behaviors of the Chelonus larva on exiting the host is depletion of the host cadaver of most remaining protein. The T. ni Ap titer in the alimentary tract of Chelonus peaks at that time and declines to zero in the first 24 h after parasitoid emergence, prior to its pupation. Aps are a source of phenolic storage compounds. Hence, premature induction of T. ni is advantageous for the parasitoid's own pupation and adult development.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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