Isolation and Structure of Diapause Hormone of the Silkworm, Bombyx mori.

The embryonic diapause of the silkworm, Bombyx mori is induced by a neuropeptide hormone, diapause hormone, which is secreted from the suboesophageal ganglion. About 55, 000 complexes of the suboesophageal ganglion and the first thoracic ganglion were dissected out from day 1 pupae of silkworms. The hormone was extracted with hot water and purified by a reverse-phase high performance liquid chromatography on a TSK gel octadecyl-4PW column. The second chromatography gave a single symmetric peak and the isolated hormone induced diapause in 20% eggs at a dose of 1.5ng/pupa. Diapause hormone has 24 amino acid residues and a molecular weight of 2645. The synthesized peptide with a carboxyl terminal as amide form exhibited the same behavior on HPLC and similar activity as the natural hormone.