The Mechanism Regulating Zebrafish Midblastula Transition

Abstract: The zebrafish midblastula transition (MBT) begins at cycle 10， in association with cell cycle lengthening， loss of cell synchrony， zygotic genome activation of transcription and appearance of cell motility. The zebrafish MBT takes place dependently on the nucleocytoplasmic ratio of embryonic cell， whereas G₁ phase emerges only at the onset of ZGA. The establishment of cell cycle checkpoint may also be controlled by transcription activation， while metaphase checkpoint responds to the inhibitory elements of DNA replication in various manners at pre-MBT and post-MBT stage， even distinct to individual stages pre-MBT. The asymmetric pattern of activated P38 plays an indispensable role to maintain the synchrony of cell division at cleavage stage. Despite that the large scale of zygotic gene expression breaks out at the onset of MBT， a few of zygotic genes involving to the differentiation of germ layers are expressed pre-MBT， in addition that some genes expressed both maternally and zygotically participate in distinct signal pathways pre-MBT and post-MBT to control the development and differentiation of embryos.

CSTR: 32200.14.cjcb.2004.03.0012