Carbohydrate changes in pre- and peri-implantation mouse embryos as detected by a monoclonal antibody.

We have examined the tissue and embryonic distribution of an antigen on a large polysaccharide that is recognized by a monoclonal antibody, IIC3, prepared against F9 teratocarcinoma cells. By immunofluorescence the antigen is first detected on compacted morulae and early blastocysts. It is strongly expressed on the primary endoderm and trophoblast of expanded blastocysts, but then disappears from the trophoblast of attached blastocysts in vitro. The binding of the antibody is completely inhibited by D-galactose and N-acetylgalactosamine. Fluoresceinated lectins were used to study further the changes in cell surface carbohydrates on trophoblast during implantation. Ricinus I, specific for terminal galactose, binds to preimplantation stages but does not bind to the trophoblast of the attached blastocyst. On the other hand, wheat germ agglutinin, specific for N-acetylglucosamine and sialic acid, binds to all preimplantation embryos and also to attached blastocysts (embryo proper and trophoblast). Neuraminidase treatment of blastocyst outgrowths enhances binding of both IIC3 and Ricinus I to the trophoblast; conversely, the binding of wheat germ agglutinin is decreased by this treatment. The results obtained in this study show changes of cell surface carbohydrates during early mouse development and suggest that sialic acid may be masking molecules on the surface of the trophoblast at the time of implantation.

Characterization of the F9 antigen(s) isolated from teratocarcinoma cell culture medium.

Anti-F9 is a syngeneic antiserum directed against mouse teratocarcinoma cells which also reacts, by complement-mediated cytotoxicity, with early mouse embryos and male germ cells. A molecule (or molecules) which specifically inhibits anti-F9, cytotoxicity can be recovered from the culture medium of undifferentiated teratocarcinoma cells. The inhibitory component is not present in the culture medium of differentiated teratocarcinoma cells or embryonic fibroblasts. The inhibitory material binds to Ricinus communis I affinity columns indicating that it contains terminal non-reducing beta-galactosyl residues. The antigenicity of the molecule does not require protein, since the inhibitory activity is completely protease-resistant. Gel filtration indicates that the protease digested inhibitory material has a molecular weight of more than 80,000.

Reexpression of a T/t-complex antigen (t12) in thymocyte x embryonal carcinoma cell hybrids.

Hybrids between PCC4 aza 1 teratocarcinoma cells and thymocytes from an adult +/t12 mouse are phenotypically embryonal carcinoma cells. They express the t 12 antigen and do not express detectable H-2 antigens. Normally t12 is only expressed early in development and on male germ cells. Thus, the thymocyte genome is reprogramed such that adult thymocyte H-2 antigen is turned off but the thymocyte genome participates in the embryonal cell phenotype by reexpressing an embryonic antigen long silent in the adult. The expression of the t12 embryonic antigen represents the first example of the activation of a gene in somatic cell hybrids that is expressed only temporally in development.