title: Expression of a complex developmental antigen in precise morphogenetic processes during chick embryogenesis.
abstract: In order to identify transitory molecules involved in specific events during development, monoclonal antibodies were raised against various structures of the chick embryo at stages exhibiting important tissue reorganization. A7H2 is a monoclonal antibody reacting with an epitope suddenly expressed in select embryonic tissues during precise morphogenetic processes. Splanchnomesoderm and most mesothelia exhibited a strong immunoreactivity during organogenesis whereas non-mesodermal A7H2-activities were usually confined to invaginating or folding epithelia. Most embryonic reactivities were transient but the amnion demonstrated a strong and persistent reactivity and therefore was selected as a source of material for A7H2-antigen characterization. The antigenic determinant was shown to be on a huge molecular complex having a pI of 5. Immunoblots obtained after SDS-PAGE demonstrated a highly disperse pattern in the high MW region of the gel that could be altered or abolished by proteolytic treatments. Fingerprint analysis of the immunoreactive peptide bands demonstrated a clear relationship between them. Using different fixation and permeabilization procedures on amnion cultured cells, we have observed that A7H2-antigen was associated with the cytoplasmic face of the plasma membrane and was resistant to treatments removing most cellular components and producing substratum-attached ventral membranes. We suggest that this macromolecular complex plays a role in specific subsets of cells involved in precise morphogenetic processes, possibly as a link with the external milieu or as a membrane associated structure.
authors.affiliation: Ontogénèse et Génétique moléculaires, Centre de Recherche du CHUL, 2705 boul. Laurier, Ste-Foy, GIV 4G2, Québec, Canada.|Département de Médecine, Université Laval, Canada.
authors.forename: Jean
authors.initials: J
authors.lastname: Duchaine
authors.affiliation: Ontogénèse et Génétique moléculaires, Centre de Recherche du CHUL, 2705 boul. Laurier, Ste-Foy, GIV 4G2, Québec, Canada.|Département de Médecine, Université Laval, Canada.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Levasseur
authors.affiliation: Ontogénèse et Génétique moléculaires, Centre de Recherche du CHUL, 2705 boul. Laurier, Ste-Foy, GIV 4G2, Québec, Canada.|Département de Médecine, Université Laval, Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: Vincent
keywords: A7H2; Chick embryo; Monoclonal antibodies; Morphogenesis