Neurosecretory cells expressing the gene for common precursor for diapause hormone and pheromone biosynthesis-activating neuropeptide in the suboesophageal ganglion of the silkworm, Bombyx mori.

Diapause hormone (DH) is a neurohormone which is secreted from suboesophageal ganglion (SG) and responsible for induction of embryonic diapause in the silkworm, Bombyx mori. DH is generated along with four other functionally different neuropeptides including pheromone biosynthesis-activating neuropeptide from the common polyprotein precursor, DH-PBAN (DHP), which is translated by a single species of mRNA. In this paper, the site of the gene expression was determined by reverse transcription-polymerase chain reaction and in situ hybridization using cDNA probe. The transcript of the DHP gene was found in SG of pupae and pharate adults, but no positive sign was detected in other tissues such as brain, thoracic ganglia, abdominal ganglia, and midgut. In situ hybridization with the cDNA clearly stained 12 cells near the ventral midline of SG which were aggregated into three clusters. The clusters were respectively localized in the mandibular, maximally, and labial neuromere of SG. The similar staining profile was observed in the SG cells at the larval, pupal, and adult stages, indicating that the DHP gene is expressed in the same set of cells throughout the postembryonic development.