Glycoconjugate Synthesis During Gastrulation inXenopus laevis

Abstract

Xenopus laevis gastrulae show more incorporation of isotopically abelled glucosamine and galactose into TCA-insoluble materials than blastulae. These materials are high molecular weight and degraded by pronase as judged by their behavior in various gel filtration media. Labelled materials migrate slowly on cellulose acetate electrophoresis, bind to DEAE—cellulose and elute at low ionic strength, but are not precipitated by cetyl pyridinium chloride (CPC) in the presence of added carrier hyaluronic acid. Pulse—chase labelling experiments and light microscopic autoradiography were used to examine secretion and deposition of glucosamine and galactose—labelled materials in different stages of developing Xenopus laeins embryos. After a 30-min pulse, grains are predominantly over cytoplasmic structures. After a 30-min pulse and a 60-min pulse chase, grains are commonly encountered over cytoplasmic structures but are predominantly localized over extracellular materials. Scanning electron microscopic studies show that extracellular fibrillar materials increase in number during gastrulation in Xenopus laevis . Increasing numbers of extracellular fibrillar structures occur in the blastocoel cavity and along the inner aspect of the roof of the lastocoel (Nakatsuji and Johnson, 1983).