2009 Fiscal Year Final Research Report
Functional evolution of the gap gene group in early embryogenesis of the insect
| Project/Area Number |
19370095
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | The University of Tokushima |
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Principal Investigator |
NOJI Sumihare The University of Tokushima, 大学院・ソシオテクノサイエンス研究部, 教授 (40156211)
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| Co-Investigator(Kenkyū-buntansha) |
OHUCHI Hideyo 徳島大学, 大学院・ソシオテクノサイエンス研究部, 准教授 (00253229)
MITO Taro 徳島大学, 大学院・ソシオテクノサイエンス研究部, 助教 (80322254)
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| Project Period (FY) |
2007 – 2009
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| Keywords | 発生進化 |
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| Research Abstract |
Most insects develop as short or intermediate germ embryos, through an ancestral mode of segmentation wherein the anterior segments are specified at the blastoderm stage and the posterior segments form in an anterior to posterior succession from a posterior growth zone. By contrast, in derived long germ insects such as Drosophila melanogaster, all segments are specified during the syncytial blastoderm stage, and maternal and gap gene products can diffuse as morphogens. To clarify how maternal and gap gene products control positional specification in phylogenetically basal insects, we analyzed the dynamic segmentation process in transgenic embryos of a hemimetabolous, intermediate-germ insect species, the cricket Gryllus bimaculatus. Here we show, using live imaging of fluorescently labelled embryonic cells and nuclei, that the positional specification of the cellular blastoderm is established during syncytium, as it is in long germ insects, though cricket blastodermal cells move dynamically to form the germband in a small posterior region of the egg. We also find that the G. bimaculatus orthodenticle gene may provide positional information for aggregating germ-anlage cells through syncytial blastoderm stages. Our findings imply a heterochronic shift in the timing of the anterior (cephalic, gnathal and thoracic) gap gene actions during evolution of a derived mode of insect embryogenesis. Our work provides new insights into an evolutionary process of early developmental mode from intermediate- to long-germ insects.
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