A cell surface differentiation antigen of Drosophila

A monoclonal antibody, generated by immunization with gastrula stage Drosophila melanogaster embryonic cells, recognizes a cell surface antigen which shows tissue and stage specificity. The antigen appears for the first time during cellularization of the blastoderm embryo and is present on all cells until around 12 hr of development. It becomes progressively restricted to specific tissues during the second half of embryogenesis. By the time of hatching, only the nervous system, germ cells, and imaginal cells are positive. During metamorphosis differentiating imaginal tissues become negative so that in the adult only the nervous system and undifferentiated germ cells are positive, with gonadal sheaths showing some staining. A third wave of antigen loss occurs during gametogenesis, resulting in negative staining on the mature sperm and oocyte. All positive tissues appear to contain the same 63-kDa cell surface antigen. The antigen behaves as a general differentiation marker lost by tissues as they approach their terminal differentiated state. The nervous system and possibly gonadal sheaths may be exceptions to this general behavior.