Removal of N-linked oligosaccharides of presumptive ectoderm impairs neural induction in Pleurodeles waltl.

Studies were carried out on the embryo of the amphibian Pleurodeles waltl to investigate the potential role of the N-linked oligosaccharides of the ectodermal cell membrane in the neural induction process. Glycopeptidase F (GPase F) was used to cleave N-linked oligosaccharides on presumptive ectoderm. Removal of oligosaccharide moieties from ectoderm membrane glycoconjugates completely inhibited natural neural induction in vitro. On the other hand, Swainsonine (Sw) and 1-deoxynojirimycin (dNM), specific inhibitors of enzymes involved in glycosylation, provoked strong and persistent changes in the structure of the N-linked oligosaccharides of presumptive ectoderm but did not prevent neuralisation of treated ectoderm. We conclude that N-linked carbohydrates are implicated in the phenomenon of neural induction. However, the structural integrity of N-linked carbohydrates of target tissue is not itself critical in this process. The existence of specific carbohydrates on presumptive ectoderm was still questioned as receptors of neural signal.