Functional Differentiation of Neurosecretory Cells with Immunoreactive Diapause Hormone and Pheromone Biosynthesis Activating Neuropeptide of the Moth, Bombyx mori

Abstract

The suboesophageal ganglion of the silkworm, Bombyx mori, contains three clusters of neurosecretory cells that are immunoreactive with antisera against the diapause hormone (DH) and the pheromone biosynthesis-activating neuropeptide (PBAN), the two neurohormones that are generated from a common precursor protein. The cells lie on the ventral midline of the ganglion. Neurosecretory cell clusters responsible for the diapause induction activity and the pheromonotropic activity of females were determined by surgically removing one or two of the three clusters of the DH/ PBAN immunoreactive cells. A potent diapause induction activity was obtained in females retaining a posterior cluster of cells while a strong pheromonotropic activity was obtained in case of females with a medial cluster. The functional differentiation of these cells may relate to different biochemical and/or physiological natures.

Mono- and dibasic proteolytic cleavage sites in insect neuroendocrine peptide precursors

“…PBAN mRNA has been demonstrated by in situ hybridization to be produced in three cell groups in the suboesophageal ganglion of Bombyx mori (Sato et al, 1994). Yet physiological evidence implicates the two anterior cell groups in the liberation of PBAN and the posterior cell group in the production of diapause hormone (Ichikawa et al, 1996). This suggests that the same precursor might be alternatively processed in the different cell groups.…”

Activity patterns of neurosecretory cells releasing pheromonotropic neuropeptides in the moth Bombyx mori

“…Six pairs of somata of neurosecretory cells expressing the gene for the precursor protein are aggregated into three clusters localized at the ventral surface of the anterior, medial, and posterior neuromeres of the suboesophageal ganglion (SOG) (9). Surgical ablation of the anterior and medial clusters of somata at an early pupal stage greatly impaired pheromone production at the adult stage, whereas the same operation on the posterior cluster impaired diapause induction rather than pheromone production, thereby suggesting functional specialization of the three classes of neurosecretory cells (10). Intracellular dye injection revealed complete structures of individual neurosecretory cells, including a unique axonal pathway and neurohemal terminals (11).…”

Regulation of bombykol production by tyramine and octopamine in Bombyx mori

“…14) In B. mori females, TA is also a possible candidate for regulating the shift in PBAN-neurosecretory cells from an active to inactive state after the start of mating. TA could act on neurosecretory cells of the SOG, in which twelve neurosecretory cells of PBAN exist 13) and the release of PBAN could be blocked. The current studies could provide useful information about the characterization and differentiation of TA and OA receptors, and may help to point the way towards developing extremely potent and relatively specific TA and OA ligands, leading to potential insecticides, although further research is necessary.…”

“…9) Mating inhibits the release of PBAN into the haemolymph, involving a substance such as Drosophila sex peptide. 10) Neural signal travelling through the VNC to the brain-suboesophageal ganglion (SOG) complexes triggers the inactivaion of PBAN secretion in the SOG, [11][12][13] however, the neural mechanism remains to be clarified. Post-mating inactivation of bombykol production is inhibited or recovered by the application of stressors, such as restrictions and anesthesia, in B. mori.…”