Biomedical subjects

D Trisler

Publications and source records attributed to D Trisler.

5 recordsLinked to original sources

PubMed1990

Cell recognition and pattern formation in the developing nervous system.

The topographic map of cell position in the avian retina is conserved and inverted when retinal ganglion neurons synapse with neurons in the optic tectum. Developmental mechanisms based on molecular gradients that specify positional information and pattern formation have been postulated in the establishment of these topographic maps of cells in retina and optic tectum. Two cell surface proteins in retina, TOP(DV) and TOP(AP), are distributed in dorsoventral and anteroposterior topographic gradients, respectively. Corresponding gradients of TOP molecules present in the tectum are inverted with respect to the retinal gradients. These orthogonal gradients of TOP(DV) and TOP(AP) molecules provide a possible Cartesian coordinate system for designation of cell position at all points in the retinotectal map.

Animals↗

PubMed1987

Corresponding spatial gradients of TOP molecules in the developing retina and optic tectum.

The topographic map of cell position in the avian retina is inverted in its projection to the optic tectum. Dorsal retinal ganglion cell axons project to ventral tectum, and ventral retinal ganglion cells project to dorsal tectum. Topographic gradients of toponymic (TOP) cell surface molecules along the dorsoventral axes of retina and tectum also are inverted. TOP molecules are most abundant in dorsal retina and ventral tectum and least abundant in ventral retina and dorsal tectum during the period of initial retinal-tectal interaction. Thus, TOP molecules may be involved in orienting the retinotectal map.

Animals↗

PubMed1987

Synapse formation in retina is influenced by molecules that identify cell position.

Molecules that identify cell type and position in the nervous system were detected by monoclonal antibodies. One molecule, TOP, is distributed in a 35-fold topographic gradient from the dorsoposterior margin to the ventroanterior margin of avian retina. The gradient is present in young embryos, increases with retinal growth, and persists in the adult. TOP molecules are present on most or all cells of retina. The number of TOP molecules detected per cell varies continuously along the axis of the antigen gradient. Thus, TOP can be used to identify position in the plane of retina along that axis. Other antigens that identify cell type and position across the thickness of retina also were detected. Molecules that mark such cellular organization may represent a neuronal recognition system. Antibodies were used to examine the role of markers of cell position in development of the nervous system. Antibody to TOP from hybridoma cells that were injected into in vivo embryo eyes diffused into the retina and bound in a topographic gradient of Ab.TOP complexes. Synapse formation in retina was inhibited in the presence of anti-TOP antibody. This suggests that TOP is involved in synapse formation and that recognition of position by neurons is necessary for normal synapse formation.

Animals↗

PubMed1986

Antibody to a molecular marker of cell position inhibits synapse formation in retina.

A topographic gradient of TOP molecules in retina can be used to identify neuron position. Antibody to TOP from hybridoma cells that were injected into in vivo embryo eyes diffused into the retina and bound in a topographic gradient of [antibody.TOP] ([Ab.TOP]) complexes. Synapse formation in retina was inhibited in the presence of anti-TOP antibody. This suggests that TOP is involved in synapse formation and that recognition of position by neurons is necessary for normal synapse formation.

Animals↗

PubMed1986

Purification of a membrane protein distributed in a topographic gradient in chicken retina.

Antigenic molecules termed TOP, which are distributed in a dorsal greater than ventral concentration gradient in chicken retina, are expressed early in development (by 48 hr after fertilization) in the optic cup of chicken embryos and continue to be expressed in retina thereafter. 35S-labeled-TOP-antibody complexes were purified by protein A-Sepharose column chromatography and subjected to NaDodSO4/polyacrylamide gel electrophoresis and autoradiography. TOP also was purified from dorsal retina by anti-TOP IgG-Affi-Gel 10 affinity column chromatography. In both cases, one major band of protein at Mr approximately 47,000 was obtained. A protein of Mr approximately 47,000 also was purified from chicken embryo brain. Cultured cells dissociated from 8-day chicken embryo retinas accumulated the amount of TOP expected of cells in the intact retina, depending on the position of the cells in the retina. TOP accumulations by cells dissociated from dorsal or ventral retina, mixed in different proportions, and cocultured were additive. These results show that TOP is a protein, that the gradient of TOP is established early in development, and that perpetuation of the gradient does not depend on the continuous presence of an extracellular gradient of diffusable molecules or on maintenance of interactions between cells.

Animals↗