A group of non-Y encoded Drosophila hydei primary spermatocyte nuclear glycoproteins exhibits epitopes depending on formation of Y chromosomal giant lampbrush loops.

In wild-type Drosophila hydei (genotype X/Y) four different primary spermatocyte nuclear glycoproteins, classified as non-Y encoded because of their occurrence in X/O genotypes, were demonstrated to possess a few epitopes that depended on formation of the Y chromosomal giant lampbrush loops threads (th; Mr 55,000 proteins) or pseudonucleolus (ps; Mr 38,000, 58,000 and 98,000 proteins). The epitopes reacted with lectins and/or antibodies in vitro lectin-/immunoreplica of primary spermatocyte total nuclear protein), and were lacking in mutants not possessing the respective loops. Those dependent on ps reacted with human sera. Epitopes restricted to proteins from th-forming spermatocytes reacted with lectin Con A (specific for D-Man and/or D-Glc) and antibodies directed against mouse immunoglobulins (AIA). In situ experiments (immunofluorescence microscopy of primary spermatocyte nuclei) revealed antibody cross-reactions with the respective loops. The reagents stained the distal (fused) sections and proximal (compact) parts of ps (human sera) or the proximal (compact) parts of th (AIA). Reaction with the latter loops was significantly repressed after absorption of AIA with the L-Fuc carbohydrate unit, classifying the AIA as fucosyl specific, and the epitopes along th as L-Fuc carbohydrate units.