FBS Colloquia No.427Laboratory for Embryogenesis
| Seminar or Lecture |
Elucidation of the Size-Control Mechanism in Early Post-implantation Embryos Daisuke Masui [D5/D5, Laboratory for Embryogenesis] High membrane potential is required for zygotic genome activation in mouse preimplantation embryos Toshihiro Aramaki [Assistant Professor, Laboratory for Embryogenesis] |
|---|---|
| Date and Time | 20 October 2026 (Tue), 12:15～13:00 |
| Place | 2F Seminar Room, BioSystems Building |
| Language | Japanese |
| Contact |
Toshihiro Aramaki (Assistant Professor) |
Elucidation of the Size-Control Mechanism in Early Post-implantation Embryos
Adult vertebrates have characteristic body sizes that are specific to each species and strain. Similarly, during development, embryos of amniotes, such as humans and turtles, at the same developmental stage exhibit relatively similar sizes. This suggests that embryonic size is not simply determined by developmental progression but is regulated within a certain range at each developmental stage. In the mouse, an experimental system has directly demonstrated the existence of a mechanism that regulates embryonic size, referred to as the “size-control mechanism.” When two 8-cell-stage embryos are fused to generate a double-sized embryo, the resulting embryo is approximately twice the size of a normal embryo until shortly after implantation. However, it becomes the same size as a normal embryo by the onset of gastrulation. Although this phenomenon was reported approximately half a century ago, its underlying molecular mechanism remains unknown. Therefore, I aimed to elucidate the size-control mechanism in early post-implantation embryos by taking advantage of this experimental system. So far, I have analyzed changes in morphogenesis and cell number, as well as investigated differences in gene expression between normal and double-sized embryos in detail. In this colloquium, I will present our results and discuss the mechanisms underlying size control in early post-implantation embryos.
High membrane potential is required for zygotic genome activation in mouse preimplantation embryos
Membrane potential has long been known to play important roles in cellular functions in neurons and muscle cells. However, the physiological roles of membrane potential during embryonic development remain poorly understood. Mouse embryos from the zygote to the cleavage stages exhibit a relatively high membrane potential compared with that of typical cells, but its functional significance during development remains unclear. To investigate the role of membrane potential in mouse early embryos, we developed a new method to manipulate the membrane potential of embryos. Artificial reduction of the membrane potential of zygote resulted in developmental arrest at the two-cell stage. Further analysis revealed that embryos with reduced membrane potential exhibited delayed chromatin reorganization and decreased gene expression from the embryonic genome, indicating impaired zygotic genome activation. Importantly, these changes were rescued by restoring the membrane potential to its normal level. Together, these results indicate that the high membrane potential of early embryos is required for zygotic genome activation after fertilization and plays an important role in the progression of embryonic development.
