IP Endocrinology

Molecular mechanism of sex pheromone production in the silkworm, Bombyx mori

S. Matsumoto 1 , N. Yokoyama 1, 2 , T. Yoshiga 1, 3 , K. Okano 4 & A. Fonagy 5

1 Molecular Entomology and Baculovirology, RIKEN, Wako-shi, 351-0198, JAPAN; 2 Dept. of Agricultural & Life Sciences, Univ. of Tokyo, Tokyo 113-8657, JAPAN; 3 Lab of Nematology, Saga Univ., Saga 840-8502, JAPAN; 4 Lab of Cell Biology, Akita Pref. Univ., Akita 010-0195, JAPAN; 5 Plant Protection Inst. Hungarian Acad. of Sciences, Budapest, II. 1525, P. O. Box 102, HUNGARY

Female moths attract conspecific males by producing and releasing species-specific pheromone blends. Biosynthesis of pheromone components takes place specifically in the pheromone gland generally associated with the intersegmental membrane between the 8th and 9th abdominal segments. Production of sex pheromones in many Lepidoptera is regulated by a neurohormone termed pheromone-biosynthesis-activating-neuropeptide (PBAN), which has been identified as a 33-34 amino acid peptide with a C-terminal FSPRLamide sequence responsible for pheromonotropic activity. In order to understand the molecular as well as cellular mechanisms of pheromone production regulated by PBAN, we have isolated functional clusters of viable pheromone producing cells of B. mori. One of the prominent morphological features of the pheromone producing cells is the abundance of large refractile granules in the cytoplasm at adult eclosion. Precise analysis on these granules revealed that the large granules at adult eclosion dramatically reduced their size and increased the number of small granules by 28 hrs after eclosion, and then reduced both number and size. These changes were prevented by decapitation and proceeded by PBAN injection. Nile Red staining and chemical characterization using FAB-MS indicated that these granules were triacylglycerols mainly composed of pheromone precursor fatty acids. Therefore, it is likely that the granules work as storage or carriers of sex pheromone precursors. Present results also suggest that the isolated cell preparation can be used for quantitative visualization of the cellular dynamics during pheromone production in B. mori. We will also discuss the expression of functional proteins and their genes involved in the process of pheromone production in B. mori.

Index terms: PBAN, cellular dynamics, pheromone biosynthesis, hormonal control, triacylglycerol.

Copyright: The copyrights of this original work belong to the authors (see right-most box in title table). This abstract appeared in Session 4 – CHEMISTRY AND PHYSIOLOGICAL ECOLOGY Symposium and Poster Session, ABSTRACT BOOK II – XXI-International Congress of Entomology, Brazil, August 20-26, 2000.