Ultrastructural localization of wheat germ agglutininbinding sites on surfaces of chick embryo cells during early differentiation

Abstract

The objective of this work was to examine changes in a surface component of cells from the chick embryo during morphogenetic migrations of gastrulation. Two electron microscope techniques were used to localize cell-bound wheat germ agglutinin (WGA), a lectin which specifically binds N-acetyl glucosamine residues. One technique involved conjugation of peroxidase to WGA before reaction with the cells; the other technique used glucose oxidase to mark WGA which was already cell-bound. In both cases, binding was revealed using diaminobenzidine. Before formation of the primitive streak, all surfaces of the two-layered embryo bound WGA. After migration of cells through the streak, to form the three-layered embryo, not all cell surfaces bound WGA equally. Epiblast cells generally bound WGA lateral to the primitive streak but not during passage through the streak. Mesenchyme cells, after passage through the streak, bound WGA increasingly as they migrated away from the streak. A WGA-binding matrix was observed in the vicinity of the mesenchyme cells and on the dorsal surface of the endoblast. The ventral surface of the endoblast bound the lectin very poorly. In some instances, a peroxidase reaction product was consistently seen on certain surfaces which was not removable by addition of the simple hapten N-acetyl glucosamine. In these cases, the density of the deposit was lessened by use of diacetyl chitobiose as a hapten. This result, together with the reduction of reaction product following certain hyaluronidase treatments, suggests that WGA may be binding to hyaluronic acid as well as membrane glycoproteins.

The masking effect of sialic acid on Con A, PNA and SBA ectoderm binding sites during neurulation in the bantam chick embryo

“…Previous authors have shown that carbohydrate moieties of glycoconjugates found at the surface of cells undergo structural modification during embryonic development (Mayli& Pfenninger and Jamieson 1980;Huck and Hatten 1981;Blanks and Johnson 1983;Fazel et al 1989). With regard to the relationship between the change of sugar residues and cell differentiation, evidence strongly suggests that lectin-binding changes occur concomitantly with differentiation of embryonic cells in sea urchins (Krach et al 1974), in chick blastoderms (Zalik and Cook 1976;Sanders and Anderson 1979), in quail neural crest cells in vitro (Sieber-Blum and Cohen 1978) and in rat neurons (Pfenninger and Mayli&Pfenninger 1979). The present study also demonstrated that there was a masking effect, i.e., anti-recognition of sialic acid, of binding sites for Con A, PNA and SBA, which had a Ordinate : the average ranking of the intensity of fluorescence from 5 embryos in each group (15 total specimens).…”

“…Thorpe et al (1988) and Loveless et al (1990) have shown how the binding sites for certain carbohydrate antibodies may be masked by sialic acid. However, less information regarding sialic acid masking of lectin-binding sites on the developing ectoderm can be found (Zalik and Cook 1976;Sanders and Anderson 1979;Slack 1985). Con A is a lectin with a broad spectrum type of specificity (Watanabe et al 1982).…”

“…1989). Few studies have used lectin on the developing ectoderm in vivo (Hook and Sanders 1977;Sanders and Anderson 1979;Currie etal. 1984;Slack 1985;Takahashi and Howes 1986;Takahashi 1988;Bergmann etal.…”

Changes in glycoconjugate expression during early chick embryo development: A lectin‐binding study

“…Con A and WGA have been ultrastructurally localized during gastrulation previously ( Hook and Sanders, 1977;Sanders and Anderson, 1979). In the case of RCA the binding was highly localized.…”

“…Lectin cytochemistry has been used extensively for this purpose in many developmental studies (reviewed by Sanders, 1986b;Damjanov, 19871, not only in the early chick embryo (Hook and Sanders, 1977;Sanders and Anderson, 1979;Takahashi and Howes, 1986;Griffith and Wiley, 19901, but also in the amphibian (Nosek, 1978) and the mammal (Currie et al, 1984;Smits-van Prooije et al, 1986;Griffith and Wiley, 1989). In the present study, we have used an extensive panel of lectins, at the light and electron microscope levels, to characterize cell surface changes in the chick embryo during gastrulation and neurulation.…”