| Co-Investigator(Kenkyū-buntansha) |
TAKEDA Reiji Shionogi Pharmaceutica Co.Ltd.Aburahi Lab.Derctor, 油日ラボラトリーズ, 研究員
FURUSAWA Toshiharu Kyoto Institute of Technology Department of Applied Biology Professor, 繊維学部, 教授 (70127166)
SATO Yukihiro Nagoya Univ. Radioisotope Research Center Assist.Professor, アイソトープ総合センター, 助手 (60222022)
IMAI Kunio Mie Univ.Fac.Bioresorces Assoc.Professor, 生物資源学部, 助教授 (80109313)
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| Research Abstract |
A neuropeptide hormone, diapause hormone (DH) is a 24 amino acid peptide amide which is responsible for induction of embryonic diapause of the silkworm, Bombyx mori. DH or its analog is a novel chemical agent to be useful for long term preservation of eggs of the polyvoltine strain of the silkworm. In order to develop some active analog of DH,we chemically synthesized more than 100 species of DH fragment analogs, and tested their diapause egg inducing activity. The result led con-clusions that the amidation of C terminus and the C-terminal pentapeptide sequence, FXPRL, are essential for expression of biological activity of DH.Thus, the C-terminal hexa peptide amide seemed to be an agonist of DH.
To obtain a new DH-like peptide which is lipophilic and permeable through integment of silkworm pupae, we extracted DH active substances from male adult heads by using an organic solvent. The active materials were purified, and one of them was isolated. The isolated substance was a peptide with a MW of about 10K,and its N-terminal amino acid sequencing showed high content of Val, Ala andPro. The peptide was weak in biological activity, but acted as a protectant against DH degradation.
DH gene was organized with 6 exons interrupted by 5 introns, and was expressed in 12 neurosecretory cells of suboesophageal ganglion. The incubation temperarture of eggs strictly affected the expression of the gene, which indicates that the environmental regulation of diapause is mediated through DH gene expression.
The chemically synthesized DH or its fragments was injected into pupae, by which treatment diapause eggs were obtained. These eggs accumulated much amounts of sorbitol and alanine as the natural diapause eggs. Thus, the DH agents are promising chemical regulators for long term preservation of eggs of polyvoltine strains of the silkworm.
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