1992 Volume 68 Issue 5 Pages 75-79
Embryonic diapause of the silkworm, Bombyx mori, is induced by a neuropeptide, diapause hormone (DH), which is secreted from suboesophageal ganglion (SG). cDNA clones for diapause hormone were isolated from a cDNA library constructed from poly A+ RNA of SG. Sequencing from 5'-end to 272 by revealed that the cDNA encodes the DH sequence which is identical to the previously isolated natural peptide except for one amino acid. The 19th amino acid of the DH deduced from the cDNA was Trp instead of Cys in the sequence of the peptide isolated previously (Bom DH-I [19-Cys]). This sequence was found in the DH preparation recently isolated from SGs of day 2 to 3 pupae of B. mori. A synthetic peptide amide with Trp at 19 exhibited biological activity comparable to the peptide amide with Cys at 19. Thus, the amidated 24 amino acid peptide with Trp at 19 is concluded to be a new diapause hormone molecule and named BomDH-I [19-Trp].
