| Co-Investigator(Kenkyū-buntansha) |
SATO Yukihiro Nagoya University, Radioisotope Research Center, Assist.Professor, アイソトープ総合センター, 助手 (60222022)
YAGINUMA Toshinobu Nagoya University, Fac.Agric., Lecturer, 農学部, 講師 (60135332)
KOBAYASHI Michihiro Nagoya University, Fac.Agric., Assoc.Professor, 農学部, 助教授 (60111837)
IMAI Kunio Mie University, Fac.Bioresorces, Assoc.Professor, 生物資源学部, 助教授 (80109313)
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| Research Abstract |
A neuropeptide, diapause hormone (DH) is responsible for induction of embryonic diapause of the silkworm, Bombyx mori. A new molecule having diapause inducing activity has been extracted from adult male heads and purified to the homogeneous state by HPLC.An apparent molecular weight of this peptide was 10,000, and the N-terminal 40 amino acid sequence was determined.
Using the cDNA encoding diapause hormone precursor (DHP), the DHP gene was cloned, and its organization and nucleotide sequence were determined. The expression of this gene was clearly found in suboesophageal ganglion (SG) of the last instar larvae and pupae, and in pharate larvae which were incubated at high temperature. Histochemical studies using cDNA and anti-DH antibody clearly revealed that DH was synthesized in 12 neurosecretory cells of SG and released into circulation through corpus cardiacum-corpora allata.
To estimate the action point of DH, we at first cloned a cDNA encoding ovary trehalase, and established a method for measurement of trehalase mRNA content in ovaries. The synthetic DH was injected into pharate adults in which ovarian development proceeds, or added to the medium for in vitro culture of ovaries. Both experiments have demonstrated that DH induces the expression of trehalase gene in ovaries, and this induction is inhibited by addition of actinomycin D, not cycloheximide. Thus, we concluded that DH expresses its function on developing ovaries to induce directly trehalase gene expression.
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