Protein Synthesis during Neural and Epidermal Differentiation in Cynops Embryo: (Cynops pyrrhogaster/protein synthesis/neural induction/concanavalin A/epidermal differentiation).

Two-dimensional gel electrophoresis was used to analyze protein synthesis in relation to neural and epidermal differentiation in Cynops pyrrhogaster embryo. Various regions of embryos at different developmental stages, from late morula to early neurula stages, were excised, radiolabelled with S-methionine, and the pattern of protein synthesis were compared. The following four types of protein spots were observed: (1) six proteins synthesized characteristically in the epidermal region of the embryo after gastrulation, (2) two proteins synthesized in both epidermal and endodermal regions, but not in other regions, after gastrulation, (3) a protein first detected at early blastula stage, of which expression was nearly constant in presumptive epidermis region but declined in the other regions, (4) the candidate for neural plate specific protein synthesized at a very high level in ectoderm explants treated with concanavalin A, a substance which evokes neural induction.

Concanavalin A Acts as a Factor in Establishing the Dorso-Ventral Gradient in the Ventral Mesoderm of Newt Gastrula Embryos : (concanavalin A/organizer/dorsalization/dorso-ventral gradient/newt).

Con A induced dorsal differentiation in the ventral mesoderm of Cynops gastrula embryo. This process apparently requires a certain amount of Con A to be internalized as supported by the following evidence: 1) Oligomannose-type oligosaccharide, a potent inhibitor of Con A, considerably inhibited dorsalization of ventral mesoderm by Con A. The incorporation of I-Con A into the ventral mesoderm was greatly inhibited by this sugar.

Inductive Capacities for the Dorsal Mesoderm of the Dorsal Marginal Zone and Pharyngeal Endoderm in the Very Early Gastrula of the Newt, and Presumptive Pharyngeal Endoderm as an Initiator of the Organization Center*: (urodele/dorsal marginal zone/pharyngeal endoderm/organization center).

The organization center of Cynops pyrrhogaster was divided into Parts 1, 2 and 3 of equal size (0.3×0.4 mm ) with presumptive fates as pharyngeal, pharyngeal+prechordal+trunk notochord, and trunk-tail notochord, respectively.

Changes of Chromosome Length and Constitutive Heterochromatin in Association with Cell Division during Early Development of Cynops pyrrhogaster embryo: (chromatin condensation/constitutive heterochromatin/cell division/ neural differentiation/amphibian embryo).

The length of chromosomes in the presumptive ectoderms of Cynops embryos was measured at nine successive cell divisions from the 6th (cleavage stage) to the 14th (gastrula stage). Up to the 10th cell division (cleavage stage) the chromosome length remained constant. At the 11th cell division the chromosomes began to shorten and continued to shorten at every cell division up to the 14th cell division.

Cell surface changes of the presumptive ectoderm following neural-inducing treatment by concanavalin A.

Scanning electron microscopic studies revealed that Concanavalin A (ConA) induces characteristic changes of the cell surface and the cell architecture of the presumptive ectoderm associated with differentiation into neural tissues. In Con A-treated cells, the filopodia with which cells were connected to each other disappeared from the interior (blastocoelic) surface and the cellular adhesivity decreased significantly. Thereafter, the cells underwent from those of the control explants.

Use of lectins as probes for analyzing embryonic induction.

Lectins were used as probes to investigate the mechanism of embryonic induction. Concanavalin (Con A) and gorse agglutinin out of 7 species of lectins tested were found to have strong neural-inducing effect on the presumptive ectoderm of newt gastrulae. Their effects were abolished by the addition of α-methyl-D-mannoside and α-L-fucose, respectively.