| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Fiscal Year 2014: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2013: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
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| Outline of Final Research Achievements |
Nucleoli in mammalian oocytes and zygotes, referred to as nucleolus precursor bodies (NPBs), are compact and morphologically different from nucleoli in somatic cells. In this study, nucleoli were removed (enucleolated) from oocytes, parthenogenetically activated pig 1-cell embryos and mouse zygotes by micromanipulation. Nucleoli of oocytes were not necessary for oocyte maturation and fertilization but, in their absence, no nucleoli were formed in zygotes, leading to their developmental failure. Enucleolated 1-cell embryos/zygotes developed to blastocysts and, after transfer of the mouse embryos to recipients, live pups were obtained. Enucleolated zygotes formed new nucleoli after several divisions. These results suggest that oocyte nucleoli are essential for embryonic development, but zygote nucleoli are not. In addition, the enucleolated zygotes formed somatic-type nucleoli during early embryonic development, demonstrating that somatic-type nucleoli do not originate from zygote NPBs.
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