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  • Key words: Subcommissural organ  (3)
  • Rat  (2)
  • 1995-1999  (4)
  • 1980-1984  (1)
  • 1
    ISSN: 1432-0878
    Keywords: Key words Subcommissural organ ; Isograft ; Xenograft ; Reissner’s fiber ; Cerebrospinal fluid ; Rat ; Bovine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The subcommissural organ (SCO) secretes glycoproteins into the cerebrospinal fluid (CSF) that aggregate and form Reissner’s fiber (RF). The factors involved in this aggregation are not known. One factor may be the hydrodynamics of the CSF when flowing through the aqueduct. This hypothesis was tested by isografting rat SCO and xenografting bovine SCO into the lateral ventricle of rats. Xenografts were either fresh bovine SCO or explants cultured for 30 days before transplantation. The grafts were investigated by electron microscopy and immunocytochemistry using antibodies against RF glycoproteins, serotonin and the glucose transporter I. Maximal time of transplantation was 43 days for isografts and 14 days for xenografts. The isografts were not reinnervated but were revascularized; they secreted into the ventricle RF glycoproteins that became progressively packed into pre-RF and RF structures identical to those formed by the SCO in situ. RF was confined to the host ventricle and at its distal end the constituent proteins disassembled. Xenografts were neither reinnervated nor revascularized and secreted into the host ventricle a material that never formed an RF. These findings indicate that the CSF factor responsible for the formation of RF is species specific, and that this process does not depend on the hydrodynamics of the CSF. The blood vessels revascularizing the isografted SCO acquired the characteristics of the vessels irrigating the SCO in situ, namely, a tight endothelium displaying glucose transporter I, and a perivascular space containing long-spacing collagen, thus indicating that basal release of glycoproteins may also occur in the grafted SCO.
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  • 2
    ISSN: 1432-0878
    Keywords: Key words: Subcommissural organ ; Reissner’s fiber ; Secretory glycoproteins ; Alkylation ; Deglycosylation ; Epitopes ; Bovine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Reissner’s fiber (RF) has been isolated, solubilized, and used to raise polycloncal antibodies. The present investigation has been designed: (1) to obtain antibodies against RF-glycoproteins in their native form (anti-RF-BI), after irreversible denaturation by alkylation (anti-RF-A), and after alkylation and deglycosylation by using endoglycosidase F (anti-RF-DE); (2) to use these antisera for a comparative immunocytochemical study of the subcommissural organ (SCO)-RF complex; (3) to establish the molecular mass of the deglycosylated RF-glycoproteins. Anti-RF-BI reacts with the SCO of all the species investigated. Anti-RF-A and anti-RF-DE only react with bovine SCO and RF. The three antisera stain the same bands in immunoblots of extracts of bovine SCO and RF, but anti-RF-A and anti-RF-DE reveal additional bands. The epitope common to all species reacting with anti-RF-BI is thus probably conformational in nature and associated with the integrity of the disulfide bonds. The lack of antibodies against conserved sequential epitopes in anti-RF-A does not support previous assumptions on the conserved nature of the SCO secretion. After deglycosylation by using endoglycosidase F, the RF-glycoproteins present a reduction in their molecular mass ranging between 10% and 25%. The three larger compounds (450, 300, and 230 kDa) lose their affinity for Limax flavus agglutinin (affinity=∧sialic acid), whereas the 190-kDa compound (170 kDa after deglycosylation) keeps its affinity for this lectin suggesting that it has N-linked and O-linked carbohydrate moieties, the three larger proteins probably having only N-linked carbohydrates.
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  • 3
    ISSN: 1432-0878
    Keywords: Key words: Subcommissural organ ; Reissner’s fiber ; Central canal ; Monoclonal antibodies ; Bovine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The subcommissural organ secretes N-linked complex-type glycoproteins into the cerebrospinal fluid. These glycoproteins condense to form Reissner’s fiber (RF), which extends along the fourth ventricle and central canal of the spinal cord. A set of three monoclonal antibodies (Mabs 3E6, 3B1, and 2A5) has been obtained using these glycoproteins as immunogens. Competitive and sandwich enzyme-linked immunoassay methods have demonstrated that the three monoclonal antibodies are directed against different epitopes, and that there is no competition among them for their binding to glycoproteins of RF. Mab 3E6 displays immunoblotting properties that are similar to those of a polyclonal antibody against the pool of glycoproteins from RF, but that are different from those of Mabs 3B1 and 2A5. All three antibodies immunostain the bovine subcommissural organ and RF. A population of ependymal cells is stained by the polyclonal antibody, and Mabs 2A5 and 3E6, but not by Mab 3B1. The material present in a population of ependymal cells of the central canal, and the glycoproteins secreted by the subcommissural organ thus probably have partial chemical identity. Some evidence suggests that the immunoreactive ependymal cells are secretory cells. The luminal surface of the central canal is coated by a thin layer of material with immunocytochemical characteristics different from those of the ependymal cells; such a coat may correspond to material released from RF.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 236 (1984), S. 171-180 
    ISSN: 1432-0878
    Keywords: Immunocytochemistry ; Ultrastructure ; Supraoptic nucleus ; Neuropil ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The neuropil located ventral to the SON was investigated by the use of immunoperoxidase staining for neurophysins, oxytocin and vasopressin, and electron miroscopy. The study was performed in six groups of rats: 1) control; 2) infusion of isotonic saline into the CSF; 3) infusion of hypertonic saline into the CSF; 4) drinking hypertonic saline for 4 days; 5) same as group 4 but injection of colchicine into the CSF on second day of dehydration; 6) salt loading for 3 months. In the control rats the ventral neuropil contained a few immunoreactive processes, the general morphology of which was completely different from that of the neurosecretory axons emerging from the SON at its dorsal aspect. In rats of groups 3 to 6 the ventral processes (VP) became loaded with neurosecretory granules, whereas the perikarya and axons were depleted. Based on their general morphology and reactivity pattern it is suggested that the VP are dendrites. Most of these “dendrites” were embedded in a glial cushion formed by the processes of a particular type of marginal glia. Some of these “dendrites” enveloped an arteriole penetrating the optic tract. All VP were rich in synaptic contacts. The possibility that the VP of neurosecretory cells may be functionally related to the subarachnoid CSF and the arteriolar blood flow is discussed.
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  • 5
    ISSN: 1432-0878
    Keywords: Key words: Subcommissural organ ; Secretory glycoproteins ; Antibodies ; Immunochemistry ; Immunocytochemistry ; Dogfish ; Scyliorhinus canicula (Elasmobranchii)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The subcommissural organ of the dogfish, Scyliorhinus canicula (L), has been investigated by use of antibodies and lectins applied to blots and tissue sections processed for light and electron microscopy. Antibodies have been raised against each of the bands that have previously been identified in immunoblots by the use of antisera raised against secretory glycoproteins extracted from the dogfish subcommissural organ, viz., the 600-kDa band and two gel regions including the 475 to 400-kDa and the 145-kDa bands obtained from preparative gels; they are referred to as Ab-600, Ab-475/400, and Ab-145. These antisera and the lectins concanavalin A and wheat germ agglutinin have been used for the staining of: (1) blots of extracts of the dogfish subcommissural organ and optic tectum; (2) tissue sections of the dogfish brain. The findings indicate that the bands of 600, 475 and 400 kDa contain compounds that should be regarded as secretory glycoproteins of the dogfish subcommissural organ. The 600-kDa and 400-kDa bands are labeled by concanavalin A; wheat germ agglutinin labels the 475-kDa band strongly and the other two weakly. Ab-600 reacts with the bands at 600, 475 and 400 kDa and stains materials stored in the rough endoplasmic reticulum and secretory granules of 200–600 nm in diameter. The 600-kDa compound is probably a precursor form. Ab-475/400 stains the same three bands revealed by Ab-600; immunocytochemically, it reacts with two types of secretory granules (200–600 and 800–1200 nm in diameter) but it does not label the rough endoplasmic reticulum. Ab-145 reveals the bands at 600, 475 and 400 kDa and a diffuse zone in the region of 145 kDa; in light-microscopic immunocytochemistry, it behaves as Ab-475/400. The 475-kDa and 400-kDa glycoproteins, and a compound of approximately 145 kDa thus probably correspond to processed forms. Ab-475/400 stains granules present in cell processes ending on local blood vessels and at the leptomeninges. Since this antiserum selectively labels secretory granules, this finding may be taken as evidence for a basal route of secretion.
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