Shigeki Yuasa

Bergmann glial development in the mouse cerebellum as revealed by tenascin expression

Tenascin, an astroglia-derived extracellular matrix molecule, is also expressed by radial glia of the embryonic mouse cerebellum. Expression of tenascin can thus be applied as a marker of astroglial development from an early stage, especially prior to the expression of the glial fibrillary acidic protein (GFAP) that can be detected in the postnatal cerebellum. The development of Bergmann glia, specialized cerebello-cortical astroglia with radial processes, was examined by tenascin immunohistochemistry and non-radioactive in situ hybridization histochemistry for tenascin mRNA in the developing mouse cerebellum. Tenascin-immunopositive radial glial processes extending from the ventricular zone to the pia mater retracted toward the cortex in the embryonic cerebellum and occupied a position corresponding to the Bergmann glial processes at the perinatal stage. Tenascin gene-expressing cells were generated in the ventricular zone of the cerbellar primordium and migrated radially toward the cortex. They were stratified in the layer of Bergmann glial somata at the early postnatal stage. They extended GFAP-immunopositive radial processes from the somata to the pia mater as revealed by double-labeling employing tenascin in situ hybridization histochemistry and GFAP-immunostaining. Bergmann glia are therefore considered to develop from cerebellar radial glia by migration of their somata and retraction of their processes. The tenascin gene-expressing cells displayed mitotic activity after alignment in the cortex as revealed by double-labeling by tenascin in situ hybridization histochemistry and immunohistochemical detection of the incorporated bromodeoxyuridine. The above findings suggest that the Bergmann glia in the cortex represent one of the origins of the astroglia in the developing cerebellum.

Neuron-glia interrelations during migration of Purkinje cells in the mouse embryonic cerebellum

The interrelations between migratory Purkinje cells and radial glial processes were examined immunohistochemically and electron‐microscopically in the fetal mouse cerebellum. Migratory Purkinje cells identified immunochemically with anti‐spot 35 antibody were apposed to the presumed radial glial processes. Putative immature migratory Purkinje cells were apposed to the radial glial processes identified immunochemically with monoclonal antibody 1DI I or anti‐tenascin antibody. Junctional specializations related to cell adhesion were observed at the sites of contact between the immature neurons and glial processes. Furthermore, coated vesicles and coated pits were noted in the contact region. These findings support the concept of contact guidance of migratory Purkinje cells by radial glial processes through cell adhesion, and also suggest the trophic interactions occurring at the region of contact.

Retrovirus-mediated gene transfer into mouse cerebellar primary culture and its application to the neural transplantation

To develop a procedure for the transplantation of genetically modified brain primary cells, we transplanted cultured mouse cerebellar cells infected with recombinant retroviruses into the cerebella of adult mice and examined the expression of introduced gene-products in the host cerebellum after transplantation. After infection of cultured cerebellar cells with recombinant retroviruses harboring chloramphenicol acetyltransferase (CAT) gene, we selected only virus-infected cells for transplantation by culturing the cells in medium containing G418 for 3 weeks. CAT was continuously expressed in the cultured cerebellar cells during the 3-week incubation, but by immunoblotting analysis with antiglial fibrillar acidic protein (GFAP) or antineurofilament protein (NFP) antiserum the population of cultured cerebellar cells was found to change during the incubation. Immunocytochemical analyses using anti-CAT antiserum demonstrated that the transplanted cell mass containing CAT-positive cells was detectable in the cerebellum up to 3 weeks, but not 3 months after the transplantation of G418-selected cells into the cerebella of 7-week-old mice.

Isolation and structure determination of a new amino acid, α-amino-γ,δ-dihydroxyadipic acid, from the hydrolysate of normal human urine

Abstract A new acidic amino acid has been isolated from the hydrolysate of normal human urine. The chemical structure of the amino acid was determined to be α-amino-γ,δ-dihydroxyadipic acid, based on its physical properties involving nuclear magnetic resonance, infrared and mass spectrometry as well as chemical degradation and chemical synthesis.