Pre-MBT patterning of early gene regulation in Xenopus: the role of the cortical rotation and mesoderm induction

摘要: Patterning events that occur before the mid-blastula transition (MBT) and organize spatial pattern of gene expression in animal hemisphere have been analyzed Xenopus embryos. We present evidence genes play a role dorsoventral specification display different modes activation. Using early blastomere explants (16-128-cell stage) cultured until gastrula stages, we demonstrate by RT-PCR analysis goosecoid (gsc), wnt-8 brachyury (bra) is dependent on mesoderm induction. In contrast, nodal-related 3 (nr3) siamois (sia) are expressed manner independent induction, however their spatially correct activation does require cortical rotation. The sia nr3 reveals half 16-cell embryo already distinctly polarized along axis as result rearrangement egg structure during Similar to antagonistic activity between ventral dorsal mesoderm, blastomeres can attenuate blastomeres. Our data suggest no Nieuwkoop center at blastula stage required for vivo.