| Project/Area Number |
60480021
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
動物発生・生理学
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| Research Institution | Tokyo Metropolitan University |
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Principal Investigator |
TOMINO Shiro Department of Biology, Tokyo Metropolitan University, 理学部, 教授 (30101075)
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| Co-Investigator(Kenkyū-buntansha) |
IZUMI Susumu Department of Biology, Tokyo Metropolitan University, 理学部, 助手 (10145659)
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥6,300,000 (Direct Cost: ¥6,300,000)
Fiscal Year 1986: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1985: ¥5,300,000 (Direct Cost: ¥5,300,000)
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| Keywords | Silkworm / Fat body / Plasma proteins / cDNA / mRNA / Gene / Transcription / 二次性徴 |
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| Research Abstract |
Expression of Storage proteins (SP 1 and SP 2) and vitellogenin in the silkworm, Bombyx mori is regulated in a stage and sex dependent fashon during development. To elucidate the molecular mechanisms bringing about the expression of secondary sexual characters in insects, biosyntheses of these plasma proteins were investigated at the level of DNA and mRNA.
A cDNA library was constructed from the fat body mRNA and plasmid clones bearing cDNA sequences complementary to the SP 1-mRNA and SP 2-mRNA, respectively, were isolated. Sequence analyses of the cloned SP 1 cDNA revealed that the SP 1-mRNA is of 2.3 kb in size carrying an open reading frame correspponding to 749 amino acid residues rich in methionine. Structural homology was noted in the deduced amino acid sequence between SP 1 and SP 2.
A bacteriophage clone carrying the SP 1 gene sequence was isolated from the B. mori gene library. The SP 1 gene is approximately 4.7kb in size composed of 5 exons interspersed with 4 introns. The initiation site of gene transcription was assigned to be at the cytosine residue, which lies 27 bases upstream of the translation initiation codon, ATG. The 5' flanking region of SP 1 gene includes TATA consensus sequence and sequences homologous to those for transcription enhancer and ecdysteroid binding sites.
A cDNA clone complementary to vitellogenin light chain-mRNA was isolated from the fat body cDNA library of vitellogenic pupae by use of a bacteriophage expression vector. RNA blot analysis with the cDNA probe have indicated that mRNA for the vitellogenin light chain is expressed only in the female vitellogenic pupae.
The cloned SP 1 genomic DNA was faithfully transcribed in a nuclear lysate prepared from the fat body of female but not of the male larvae, indicating the possibility that tans-acting cellular factor(s) participates in the stage and sex specific transcription of the SP 1 gene.
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