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. Succinyl-Con A had a weak inducing activity in comparison to Con A. Autoradiography of3H-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.3H-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.