Use of lectins as probes for analyzing embryonic induction

Abstract

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. Succinyl-Con A had a weak inducing activity in comparison to Con A. Autoradiography ofH-Con A-treated explants revealed that Con A bound to the inner surface, but not to the outer surface of ectoderm and was successively incorporated into cytoplasm.H-Thymidine incorporation was lower in the first half and higher in the second half of the 60 h cultivation period in Con A-treated explants as compared to controls.Con A-Sepharose had a strong inductive effect. This suggests that neural induction is caused through Con A binding to the plasma membrane, but not through incorporation into the cytoplasm of the ectoderm cells.

Noggin upregulates Fos expression by a calcium‐mediated pathway in amphibian embryos

“…We found that the upregulation of a FOS-related protein, determined immunochemically, can be induced in animal cap explants of early gastrula (stage 8a) of the amphibian Pleurodeles waltl by noggin as well as by the lectin Con A, which also has neuralizing properties (Takata et al 1981;Gualandris et al 1985 (Murphy et al 1991). In the pheochromocytoma cell line PC12, the mechanism by which L-type voltage-sensitive calcium channels regulate c-fos transcription has been extensively studied (Morgan & Curran 1986; Piechaczyk & Blanchard 1994).…”

Concanavalin A Acts as a Factor in Establishing the Dorso‐Ventral Gradient in the Ventral Mesoderm of Newt Gastrula Embryos1

“…This may be explained by the fact that the oligosaccharide has a higher association constant with Con A than the simple sugar methyl-a-D-mannoside (1 8). It is interesting to note that neural induction by Con A was greatly inhibited by methyl-a-D-mannoside even at 1 mM concentration (30).…”

“…It has been shown that Con A can induce the competent ectoderm to form archencephalic neural tissues (8,10,17,30). The mode of action of Con A seems very similar to that of the living organizer factor (29).…”

“…The mode of action of Con A seems very similar to that of the living organizer factor (29). Neural induction by Con A is apparently receptor-mediated and its oligomannose-type oligosaccharide-containing receptors appear to be localized on the interior surface of the competent ectoderm (29,30).…”

“…Con A immobilized on Sepharose beads has been known to induce neural tissues as efficiently as free Con A when applied to the presumptive ectoderm (30,31). Surprisingly, Con ASepharose beads did not cause dorsalization of the ventral mesoderm.…”