A comparative immunocytochemical and immunochemical analysis of glycoproteins synthesized in the bovine subcommissural organ.

To extend our previous immunochemical investigations in the chick embryo (Karoumi et al., 1990 b), we raised antibodies in the rabbit against crude extracts of the subcommissural organ (SCO) of the bovine. The antiserum labeled A99 was absorbed by crude brain extracts and its specificity was tested by different techniques. Comparison of crude SCO and cerebral hemispheres supernatants after immunoblotting allow to identify specific 98, 60, 52, 42, 38, and 32 kDa polypeptides in the SCO profile. Immunoaffinity chromatography on A99 immunoadsorbent of crude SCO, cerebral hemispheres (CH) and classical ependyma (CE) supernatants was followed by electrophoretical analysis and electrotransfer. Concanavalin A (Con A) and wheat germ agglutinin (WGA) labeling procedures demonstrated the presence of numerous glycopeptides specific of crude SCO supernatants and having an apparent molecular weight ranging from 240 to 50 kDa. In the CH-eluted fraction, 50 and 52 kDa glycopeptides were revealed by ConA and WGA, whereas in the CE-immunopurified fraction no band was visualized. The similarity of the chick embryo and bovine electrophoretic pattern corresponding to the SCO eluted fractions speaks in favour of a high degree of conservation of the SCO secretory material and an evolutionary stability of the antigens recognized by A99IgG.