Glycoprotein synthesis in the subcommissural organ of the chick embryo

Abstract

Antibodies were raised in rabbit against crude subcommissural organ (SCO) extract of 19 day old chick embryos. After absorption with crude brain extract, the IgG fraction was purified by ion exchange chromatography. The specificity of the antibodies was controlled by immunostaining and by a competition test between lectins (Concanavalin A-Con A- and wheat germ agglutinin-WGA-) and antibodies (A74 IgG). Using A74 IgG, some ependymal cells containing immunoreactive material (IRM) could be detected in the SCO anlage at 4 days of incubation. During the following stages (5 to 12 days), the immunostaining extended caudal-ward in the SCO epithelium according to a rostro-caudal gradient of differentiation. The appearance of IRM in the secretory ependymal cells of the SCO parallel that of Concanavalin A-positive glycoproteins (Bruel et al., 1987). Secretion of IRM into the ventricular cavity, contributing to the formation of Reissner's fiber (RF) occurred during the 7th day of incubation. The formation of RF was examined at different levels of the spinal cord using A74 IgG, WGA and aldehyde fuchsin (AF) staining. The appearance of SCO specific glycoproteins was observed at 11 days in the central canal but the presence of a non-immunoreactive material at 10 days suggests that the formation of RF probably happens inside a guidance material.

Tenascin-Y in the Developing and Adult Avian Nervous System

“…Remarkably similar staining of long, beaded processes has been observed by others using antibodies raised against the glycoproteins of Reissner's fiber, a thread-like strand of extracellular matrix that extends the length of brain ventricles and into the spinal cord's central canal [Karoumi et al, 1990;Rodriguez et al, 1996;Perez et al, 1996;Yulis et al, 1998]. Our staining pattern indicates that tenascin-Y in the chicken, and probably tenascin-X in mammals, is in either Reissner's fiber or more nebulous parts of the ventricular matrix.…”

Otoc1: A novel otoconin‐90 ortholog required for otolith mineralization in zebrafish

“…Interestingly, these anatomical sites of otoc1 expression coincide almost exactly with the expression of Reissner's substance (Lichtenfeld et al, 1999;Lehmann and Naumann, 2005). Reissner's substance is a mixture of glycoproteins, including SCO-spondin (also called Reissner's Fibre -Gly1) (Herrera and Rodriguez, 1990;Karoumi et al, 1990;Nualart et al, 1991Nualart et al, , 1998Gobron et al, 1996;Didier et al, 2000;Lehmann et al, 2001;Meiniel, 2001), that are secreted from the floor plate, flexural organ, and subcommissural organ (SCO) in zebrafish and other vertebrate species. Reissner's substance is secreted by cells of the SCO into the ventricle where it aggregates into a threadlike structure called Reissner's fibre, which extends the entire length of the central canal of the spinal cord.…”

The subcommissural organ

“…Indeed, antibodies raised against RF glycoproteins react specifically with the secretory material of the SCO Rodríguez et al, 1984a;Sterba et al, 1981Sterba et al, , 1982. In contrast, antibodies against secretory products extracted from the SCO immunostain the RF (Grondona et al, 1994a;Karoumi et al, 1990;S. Rodríguez et al, 1985).…”

“…Antisera raised against bovine RF glycoproteins after an irreversible cleavage of the disulfide bonds by alkylation or after alkylation and deglycosylation are strongly reactive with the bovine SCO-RF complex, but do not react with the SCO of other species, indicating that the conserved epitope is conformational in nature (Nualart and Rodríguez, 1996). Polyclonal antibodies have also been raised against extracts of the SCO proper (Grondona et al, 1994a;Karoumi et al, 1990;S. Rodríguez et al, 1985) or against specific glycoproteins collected from preparative gels of SCO extracts (López-Avalos et al, 1995;Nualart et al, 1991).…”

“…In the chick, with an ontogenetical period of 21 days, already at the third embryonic day (E-3), a group of cells located in the dorsal wall of the diencephalic vesicle display a material reactive with anti-RF sera (Karoumi et al, 1990;R. Meiniel et al, 1993;Naumann et al, 1987;Schöebitz et al, 1986).…”