אסיף מאגר המחקר החקלאי

Modulation of the PBAN-stimulated of pheromonotropic activity in Helicoverpa armigera

Year:

1995

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Volume :

25

Co-Authors:

Rafaeli, A., Department of Stored Products, Volcani Center, P.O. Box 6, Bet Dagan, 50250, Israel
Gileadi, C., Department of Stored Products, Volcani Center, P.O. Box 6, Bet Dagan, 50250, Israel

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Abstract:

An extensive study of the effect of octopamine on pheromonotropic activity was initiated. Octopamine (1 mM), tyramine (1mM) and K+(100 mM) were observed to inhibit the pheromonotropic action due to PBAN in pheromone gland incubations. The biogenic amine inhibition was reversed in the presence of the antagonists phentolamine and yohimbine. The pheromonostatic action of octopamine was dependent on the PBAN concentration in the incubation medium. Octopamine, at concentrations of 0.1 and 1 mM, significantly inhibited the pheromonotropic action of 1 and 5μM PBAN after a minimum of 2 h incubation in vitro. This inhibitory action was evident on the production of Z11-hexadecenal, the main pheromone component, (analysed by thin-layer and gas chromatography) as well as the fatty acid fraction (analysed by thin-layer chromatography) in the intersegmental membrane portion of pheromone gland incubations. No significant pheromonotropic or pheromonostatic effect was observed in incubations of the 8th segment alone. The pheromonostatic action was also evident at the cellular level (inhibition of the production of intracellular cAMP) but only in the intersegmental membrane portion of pheromone gland incubations. On the other hand, in incubations of the 8th segment alone, octopamine stimulated intracellular cAMP levels. Pulse-chase experiments, using the precursor 14C sodium acetate, showed that the pheromonostatic activity was not due to an increase in the release or degradation rate of the pheromone component but due to an inhibition in biosynthesis. The pheromonostatic action of octopamine was confirmed by experiments in vivo. The physiological significance of the action of octopamine is discussed. © 1995.

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