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Characterization of cell surface antigen L2 recognized by monoclonal antibody
223
Characterization
of cell surface antigen L2 recognized
by monoclonal
antibody
Schachner, M., Rathjen, R. and Wernecke, H., Dept. Neurobiology, Univ. Heidelberg Heidelberg, West Germany L2 antigen is expressed at the cell surface of neurons and glia in the developing embryonic and postnatal mouse cerebellar cortex. In monolayer cultures the antigen is strongly detectable on an immature neural subpopulation which expresses tetanus toxin receptors, vimentin, which is an early astroglial marker, and, to a considerably lower degree, glial fibrillary acidic protein. Most, but not all of these L2 antigen-positive cells also express the developmentally early oligodendroglial marker 04 antigen, but not 01 antigen which is characteristic of more differentiated oligodendrocytes. Antigen A2B5 is also expressed on these cells. Immunoaffinity purification of L2 antigen yields five bands by SDS-PAGE with apparent molecular weights of 225, 200, 180, 140 and 70 kilodaltons.
A monoclonal antibody that decreases synapses in developing retina. Trisler, D., Nirenberg, M. Laboratory of Biochemical Genetics, National Heart, Lung and Blood Institute , National Institutes of Health, Bethesda, Maryland 20205, USA A 35-fold dorsal-ventral gradient of a plasma membrane protein (TOP) in chick neural retina, that can be used as a marker of cell position, has been identified by the use of a monoclonal antibody obtained by the fusion of P3X63Ag8 myeloma cells with spleen cells from mice imlunized with 14-day chick embryo dorsal retina (Trisler et al., Proc. Natl. Acad. Sci., (1981) 78 2145). Ten and ii day embryos were inje-cted--i-n-~rao--~lar--l-~wit--h---antibody t-o--TOP or antibody synthesized by P3x63Ag8 cells or 5 x I0 U hybridoma cells or P3x63Ag8 cells synthesizing antibody. Antibody injected into the vitreal space of the embryonic chick eye in ovo diffused into the retina and bound to retina cells in a gradient of the same magnitude and orientation as was.measured by in vitro binding studies. [Antibody-TOP] complexes, detected by irmmunofluorescence, were most abundant in the outer and inner synaptic layers and in the ganglion neuron axon layer of the retina. [Antibody-TOP] gradients were detected in retina 24 hours after intraoccular injection. The gradients persisted for 3 days when anti-TOP IgG 1 was injected and for i0 days when hybridoma cells were injected. Electron microscopic results demonstrated that the inner synaptic layer of retinas from eyes of embryos injected with anti-TOP IgG were less mature than those from eyes injected with control P3X63 Ag8 antibody or cells or from uninjected eyes. Fewer synapses were observed in retinas that had been exposed to anti-TOP IgG, the packing of neurites in the inner synaptic layer was looser, and the number of growth cones was greater than that found with control retinas.
ROUNDTABLE
IO
"The Directionality of Receptor Changes Consequent to Exposure of Neonates to Neurotoxic Agents" Bondy, S.C., Laboratory of Behavioral and Neurological Toxicology, National I n s t i tutes of Environmental Health Sciences, Research Triangle Park, NC 27709, U.S.A. Damage to neuronal c i r c u i t r y of adult animals frequently results in elevation of postsynaptic neurotransmitter receptor density, denervation supersensitivity being a consequence of this. On the other hand, similar damage in developing animals may retard normal receptor ontogenesis. Thus, receptor changes occurring in a young animal exposed to a neurotoxic agent may be in a direction opposite to that found in a similarly treated adult. This difference has been found in s t r i a t a l dopamine binding sites of adult rats treated with acrylamide, chlordecone, or haloperidol, in comparison to gestationally exposed rats. There may be a c r i t i c a l difference in receptor response to denervation of a mature neuron and non-innervation of a developing neuron.
Characterization
of cell surface antigen L2 recognized
by monoclonal
antibody
Schachner, M., Rathjen, R. and Wernecke, H., Dept. Neurobiology, Univ. Heidelberg Heidelberg, West Germany L2 antigen is expressed at the cell surface of neurons and glia in the developing embryonic and postnatal mouse cerebellar cortex. In monolayer cultures the antigen is strongly detectable on an immature neural subpopulation which expresses tetanus toxin receptors, vimentin, which is an early astroglial marker, and, to a considerably lower degree, glial fibrillary acidic protein. Most, but not all of these L2 antigen-positive cells also express the developmentally early oligodendroglial marker 04 antigen, but not 01 antigen which is characteristic of more differentiated oligodendrocytes. Antigen A2B5 is also expressed on these cells. Immunoaffinity purification of L2 antigen yields five bands by SDS-PAGE with apparent molecular weights of 225, 200, 180, 140 and 70 kilodaltons.
A monoclonal antibody that decreases synapses in developing retina. Trisler, D., Nirenberg, M. Laboratory of Biochemical Genetics, National Heart, Lung and Blood Institute , National Institutes of Health, Bethesda, Maryland 20205, USA A 35-fold dorsal-ventral gradient of a plasma membrane protein (TOP) in chick neural retina, that can be used as a marker of cell position, has been identified by the use of a monoclonal antibody obtained by the fusion of P3X63Ag8 myeloma cells with spleen cells from mice imlunized with 14-day chick embryo dorsal retina (Trisler et al., Proc. Natl. Acad. Sci., (1981) 78 2145). Ten and ii day embryos were inje-cted--i-n-~rao--~lar--l-~wit--h---antibody t-o--TOP or antibody synthesized by P3x63Ag8 cells or 5 x I0 U hybridoma cells or P3x63Ag8 cells synthesizing antibody. Antibody injected into the vitreal space of the embryonic chick eye in ovo diffused into the retina and bound to retina cells in a gradient of the same magnitude and orientation as was.measured by in vitro binding studies. [Antibody-TOP] complexes, detected by irmmunofluorescence, were most abundant in the outer and inner synaptic layers and in the ganglion neuron axon layer of the retina. [Antibody-TOP] gradients were detected in retina 24 hours after intraoccular injection. The gradients persisted for 3 days when anti-TOP IgG 1 was injected and for i0 days when hybridoma cells were injected. Electron microscopic results demonstrated that the inner synaptic layer of retinas from eyes of embryos injected with anti-TOP IgG were less mature than those from eyes injected with control P3X63 Ag8 antibody or cells or from uninjected eyes. Fewer synapses were observed in retinas that had been exposed to anti-TOP IgG, the packing of neurites in the inner synaptic layer was looser, and the number of growth cones was greater than that found with control retinas.
ROUNDTABLE
IO
"The Directionality of Receptor Changes Consequent to Exposure of Neonates to Neurotoxic Agents" Bondy, S.C., Laboratory of Behavioral and Neurological Toxicology, National I n s t i tutes of Environmental Health Sciences, Research Triangle Park, NC 27709, U.S.A. Damage to neuronal c i r c u i t r y of adult animals frequently results in elevation of postsynaptic neurotransmitter receptor density, denervation supersensitivity being a consequence of this. On the other hand, similar damage in developing animals may retard normal receptor ontogenesis. Thus, receptor changes occurring in a young animal exposed to a neurotoxic agent may be in a direction opposite to that found in a similarly treated adult. This difference has been found in s t r i a t a l dopamine binding sites of adult rats treated with acrylamide, chlordecone, or haloperidol, in comparison to gestationally exposed rats. There may be a c r i t i c a l difference in receptor response to denervation of a mature neuron and non-innervation of a developing neuron.