Vertebrate body axis formation depends on a population of bipotential neuromesodermal cells along the posterior wall of the tailbud that make a germ layer decision after gastrulation to form spinal cord and mesoderm. Despite exhibiting germ layer plasticity, these cells never give rise to midline tissues of the notochord, floor plate and dorsal endoderm, raising the question of whether midline ...

Changes in protein synthesis during early Ambystoma mexicanum (axolotl) embryogenesis were monitored using two-dimensional (2-D) polyacrylamide gel electrophoresis. No change in synthesis patterns during progesterone-induced oocyte maturation was detected. In oocytes matured in vivo (unfertilized eggs), however, the synthesis of several oogenetic proteins ceased, only to be resumed later in dev...

In the gastrula stage embryo, the epiblast migrates toward the primitive streak and ingresses through the primitive groove. Subsequently, the ingressing epiblast cells undergo epithelial-mesenchymal transition (EMT) and differentiate into the definitive endoderm and mesoderm during gastrulation. However, the developmental mechanisms at the end of gastrulation have not yet been elucidated. Histo...

Major developmental events in early Xenopus embryogenesis coincide with changes in the length and composition of the cell cycle. These changes are mediated in part through the regulation of CyclinB/Cdc2 and they occur at the first mitotic cell cycle, the mid-blastula transition (MBT) and at gastrulation. In this report, we investigate the contribution of maternal Wee1, a kinase inhibitor of Cyc...

Here we show that Ephrin–Eph signaling regulates Xenopus gastrulation via mediating tissue separation. XEph receptor is exclusively expressed in the involuting mesoderm, whereas XEphrin ligand is localized in the ectoderm region during Xenopus gastrulaiton. At the beginning of gastrulation, XEph expressing mesoderm is around blastopore lip, and XEphrin ligand expressing ecotoderm is placed righ...

Gastrulation in amphibian embryos is a composition of several differently located morphogenetic movements which are perfectly coordinated with each other both in space and time. We hypothesize that this coordination is mediated by biomechanical interactions between different parts of a gastrulating embryo based upon the tendency of each part to hyper-restore the value of its mechanical stress. ...

During animal gastrulation, the specification of the embryonic axes is accompanied by epithelio-mesenchymal transition (EMT), the first major change in cell shape after fertilization. EMT takes place in disparate topographical arrangements, such as the circular blastopore of amphibians, the straight primitive streak of birds and mammals or in intermediate gastrulation forms of other amniotes su...

Par (partitioning-defective) genes were originally identified in Caenorhabditis elegans as determinants of anterior/posterior polarity. However, neither their function in vertebrate development nor their action mechanism has been fully addressed. Here we show that two members of Par proteins, 14-3-3 (Par-5) and atypical PKC (aPKC), regulate the serine/threonine kinase Par-1 to control Xenopus g...

Dickkopf-1 (Dkk1) is a secreted protein that negatively modulates the Wnt/ catenin pathway. Lack of Dkk1 function affects head formation in frog and mice, supporting the idea that Dkk1 acts as a “head inducer” during gastrulation. We show here that lack of Dkk1 function accelerates internalization and rostral progression of the mesendoderm and that gain of function slows down both internalizati...