Analysis of the secretory glycoproteins of the subcommissural organ of the dogfish (Scyliorhinus canicula)

The subcommissural organ

“…Ultrastructural immunocytochemistry using polyclonal and monoclonal antibodies has demonstrated strong labeling of the secretory material located in the dilated RER cisternae (Figs. 15, 16) and the secretory granules located at the apical cell pole (Grondona et al, 1994b;Lösecke et al, 1984;Pérez et al, 1995;Peruzzo et al, 1990;Rodríguez et al, 1986Rodríguez et al, , 1987a and in the vascular and leptomeningeal ependymal endings Rodríguez et al, 1987b). There are monoclonal antibodies that react with the secretory granules but not with the RER content .…”

“…The combined use of immunocytochemistry (anti-RF serum), lectins, and specific glycosidades applied in sequence to the same sections led to the following conclusions: (1) the secretory products within the RER are N-linked, high-mannose-type glycoproteins; (2) the products within the apical secretory granules are N-linked, complex-type glycoproteins, with the sequence in the terminal chain of -GlcNac-Galsialic acid; and (3) the apical secretory granules and the pre-RF material share the same immunocytochemical and lectin binding properties (Ferná ndez-Llebrez et al, 1987;Grondona et al, 1994b;Herrera and Rodríguez, 1990;Nualart et al, 1991;Rodríguez et al, 1986Rodríguez et al, , 1987bRodríguez et al, , 1990; S. Rodríguez et al, 1987). Ultrastructural lectin histochemistry has confirmed these observations (Grondona et al, 1994b;Peruzzo et al, 1990;Rodríguez et al, 1986). Core glycosylation of the SCO glycoproteins was confirmed by the disappearance of the Con-A binding sites after the in vivo administration of tunicamycin (Herrera and Rodríguez, 1990).…”

“…This property and the fact that, in the SCO, the RER is the main storage site of the secretion characterize the SCO as a rather unique type of gland. Grondona et al (1994b) described, in the dogfish S. canicula, typical apical secretory granules and lysosomelike granules located in the supranuclear region that react with an anti-RF serum. They suggested that some of the glycoproteins synthetized by the SCO (incorrect folding?, incorrect glycosylation?)…”

“…Secretory glycoproteins of high molecular mass (in the range of 400-600 kDa) have been detected by immunoblotting in the SCO of the dogfish (Grondona et al, 1994b;López-Avalos et al, 1995) and the SCO of chick embryos (Didier et al, 1995).…”

Biosynthesis and molecular biology of the secretory proteins of the subcommissural organ

“…The 600-kDa would be a precursor form. Grondona et al (1994) Bi-dimentional electrophoretic analysis of fetal chick SCO extracts. Analysis with lectins and antibodies.…”