2000 Fiscal Year Final Research Report Summary
Mechanism of axis formation and mesoderm induction in early development
| Project/Area Number |
11680724
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Developmental biology
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| Research Institution | Hiroshima University |
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Principal Investigator |
AKASAKA Koji Hiroshima Univ., Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (60150968)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Animal-Vegetal axis / Induction / Mesoderm / T-brain / Ets / Wnt signaling / Sea Urchin |
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| Research Abstract |
Large micromere descendant cells (primary mesenchyme cells : PMCs) play a key role of the sea urchin development. We have demonstrated that HpEts is involved in the differentiation of PMCs in sea urchin Hemicentrotus pulcherrimus embryos. The expression of HpEts is restricted to PMCs after the hatching blastula stage, however, the HpEts mRNA is ubiquitously distributed in the embryo during early cleavage stage. Here we investigated the role of HpEts protein in the early development of sea urchin embryo. The specific antibodies to the HpEts protein revealed that HpEts proteins exist in the cytoplasm of all the embryonic cells during early cleavage stage. Thus, HpEts does not seem to function as a transcription factor, although the function of HpEts in the cleavage stage is still unclear. After the blastula stage, the HpEts protein starts to be accumulated into the nuclei of PMCs. We suggest that the HpEts begins to function as a transcription factor just before the PMCs start to ingress into the blastocoel. We also investigated that the function of T-box gene in sea urchin development. We presented an evidence for an involvement of a T-box gene (HpTb) in PMCs differentiation of the embryos. Molecular phylogenetic analysis suggested that HpTb is a member of the T-brain subfamily. HpTb is expressed transiently from hatched blastula stage through mesenchyme blastula stage to the gastrula stage. The expression of HpTb is restricted to the PMCs, and the HpTb expression is controlled by nuclear localization of β-catenin suggesting that HpTb is in a downstream component of the Wnt signalling cascade. We also provided an evidence suggesting that HpTb is involved in the induction of initiation of gastrulation.
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