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Zebrafish maternal-effect mutations causing cytokinesis defect without affecting mitosis or equatorial vasa
Yasuyuki Kishimoto1, Sumito Koshida, Makoto Furutani-Seiki
1Kondoh Differentiation Signaling Project (ERATO), Japan Science and Technology Corporation, 14 Yoshida-Kawaramachi, Sakyouku, Kyoto 606-8305, Japan. ykishimo@lab.nig.ac.jp
Mechanisms of Development
|January 7, 2004
Summary
Maternal-effect genes are crucial for early embryonic development. Mutations in these genes disrupt cell division (cytokinesis) but not nuclear division, revealing key aspects of embryonic cell architecture.
Area of Science:
- Developmental Biology
- Genetics
- Cell Biology
Background:
- Maternal-effect genes are vital for early embryogenesis before zygotic gene activation.
- Understanding these genes is crucial for deciphering fundamental developmental processes.
Purpose of the Study:
- To identify and characterize maternal-effect genes involved in early embryogenesis using a genetic screen.
- To investigate the role of specific mutations in cell cleavage and embryonic development.
Main Methods:
- An F3 genetic screen strategy was employed to identify recessive mutations.
- Six recessive mutations affecting maternal-effect genes were identified from 60 mutagenized genomes.
- Phenotypic analysis focused on cell cleavage, nuclear division, and cytoskeletal organization in mutant embryos.
Main Results:
- Three acytokinesis mutations (ackkt5, ackkt62, ackkt119) were identified, causing a complete absence of cell cleavage.
- Mutations disrupted contractile ring formation and cortical F-actin organization, essential for cytokinesis.
- Despite the lack of cell cleavage, nuclear divisions proceeded normally, and maternal mRNAs localized correctly.
Conclusions:
- These acytokinesis mutations provide insights into the sequential events of cytokinesis, particularly cortical actin dynamics.
- Early embryonic cell architecture is established by the mitotic apparatus independently of cell cleavage.
- The study highlights the distinct roles of nuclear division and cell cleavage in early embryonic patterning.