- Email: [email protected]
Genetic and epigenetic control of the connectivity and responsiveness of cerebellar purkinje cells in rodents
204
Cell lineage and cell interaction in leech neurogenesis. Weisblat, David A. , Molecular Biology, UC Berkeley, Berkeley, CA 94710 USA Both the early embryo of the leech and the segmental ganglia of this annelid worm contain relatively large, identifiable cells accessible to physiological manipulation. In early development, the leech egg undergoes a stereotyped series of cleavages generating five bilateral pairs of segmental precursor blastomeres, the M (mesodermal) and N, O, P and Q (ectodermal) teloblasts. Subsequently, each teloblast contributes a column of progeny blast cells to a longitudinally arrayed set of cells called the germinal plate, from which the ventral nerve cord ganglia and other segmental tissues arise. By injecting tracer substances such as horseradish peroxidase or fluorescently labeled peptides into various teloblasts in the early embryo, it has been shown that each teloblast, including even the mesodermal precursor teloblasts (M), contribute a characteristic subset of neurons to the ipsilateral half-ganglia in normal development. This indication of a highly determinate development for the leech is largely supported by the neuronal deficits observed in teloblast ablation experiments. However, a number of observations suggest that the O and P teloblasts differ from the others in that they are of equal developmental pluripotency, and that the fates of their progeny are determined on the basis of a positional hierarchy within the developing embryo.
Genetic regulation of myelin basic protein expression in the mouse brain. Carson, J.H. Department of Biochemistry, University of Connecticut Health Center, Farmington, CT Mouse central nervous system myelin contains a family of polypeptides which are immunologically and structurally related to myelin basic protein. Each of these polypeptides has a characteristic developmental profile of accumulation which is regulated by a combination of factors including: the total level of myelin basic protein mRNA, the level of mRNA for each polypeptide, the translational efficiency of each mRNA species in vivo, and the post-translational s t a b i l i t y of each polypeptide. Mutations such as jimpy, quaking, and shiverer which interfere with myelin morphogenesis in the central nervous system perturb the developmental program of myelin basic protein gene expression in characteristic ways. By analyzing the phenotypic effects of these mutations on the various factors regulating myelin basic protein expression in the central nervous system we have attempted to elucidate the relationship between myelin basic protein gene expression and myelin morphogenesis.
SY~IPOS IU~! 8
Genetic and epigenetic control of the connectivity and responsiveness of cerebellar purkinje cells in rodents. F. CREPEL. Units INSERM U 97, Paris, France. During development of the cerebellum, the adult one-to-one relationship between climbing fibres and Purkinje cells is preceded by a transiant stage of multiple innervation (Crepel et al, 76). In this report,the mechanisms involved in the regression of the supernumerary synapses, and the role of this remodelling in the postnatal shaping of olivocerebellar connections will be considered in the light of results obtained from strains of mutant mice and X-irradiated rats in which the development of the cerebellum is abnormal. This report will also presents recent evidences indicating that a genetic dissection of ionic conductances and chemosensitivity of central neurons can be achieved in mammals by the use of mutant mice. In particular, it will be shown that the staggerer mutation leads to a selective absence of calcium spikes in oerebellar Purkinje cells, and that this defect is probably due to a direct impact of the mutation on these cells.
Cell lineage and cell interaction in leech neurogenesis. Weisblat, David A. , Molecular Biology, UC Berkeley, Berkeley, CA 94710 USA Both the early embryo of the leech and the segmental ganglia of this annelid worm contain relatively large, identifiable cells accessible to physiological manipulation. In early development, the leech egg undergoes a stereotyped series of cleavages generating five bilateral pairs of segmental precursor blastomeres, the M (mesodermal) and N, O, P and Q (ectodermal) teloblasts. Subsequently, each teloblast contributes a column of progeny blast cells to a longitudinally arrayed set of cells called the germinal plate, from which the ventral nerve cord ganglia and other segmental tissues arise. By injecting tracer substances such as horseradish peroxidase or fluorescently labeled peptides into various teloblasts in the early embryo, it has been shown that each teloblast, including even the mesodermal precursor teloblasts (M), contribute a characteristic subset of neurons to the ipsilateral half-ganglia in normal development. This indication of a highly determinate development for the leech is largely supported by the neuronal deficits observed in teloblast ablation experiments. However, a number of observations suggest that the O and P teloblasts differ from the others in that they are of equal developmental pluripotency, and that the fates of their progeny are determined on the basis of a positional hierarchy within the developing embryo.
Genetic regulation of myelin basic protein expression in the mouse brain. Carson, J.H. Department of Biochemistry, University of Connecticut Health Center, Farmington, CT Mouse central nervous system myelin contains a family of polypeptides which are immunologically and structurally related to myelin basic protein. Each of these polypeptides has a characteristic developmental profile of accumulation which is regulated by a combination of factors including: the total level of myelin basic protein mRNA, the level of mRNA for each polypeptide, the translational efficiency of each mRNA species in vivo, and the post-translational s t a b i l i t y of each polypeptide. Mutations such as jimpy, quaking, and shiverer which interfere with myelin morphogenesis in the central nervous system perturb the developmental program of myelin basic protein gene expression in characteristic ways. By analyzing the phenotypic effects of these mutations on the various factors regulating myelin basic protein expression in the central nervous system we have attempted to elucidate the relationship between myelin basic protein gene expression and myelin morphogenesis.
SY~IPOS IU~! 8
Genetic and epigenetic control of the connectivity and responsiveness of cerebellar purkinje cells in rodents. F. CREPEL. Units INSERM U 97, Paris, France. During development of the cerebellum, the adult one-to-one relationship between climbing fibres and Purkinje cells is preceded by a transiant stage of multiple innervation (Crepel et al, 76). In this report,the mechanisms involved in the regression of the supernumerary synapses, and the role of this remodelling in the postnatal shaping of olivocerebellar connections will be considered in the light of results obtained from strains of mutant mice and X-irradiated rats in which the development of the cerebellum is abnormal. This report will also presents recent evidences indicating that a genetic dissection of ionic conductances and chemosensitivity of central neurons can be achieved in mammals by the use of mutant mice. In particular, it will be shown that the staggerer mutation leads to a selective absence of calcium spikes in oerebellar Purkinje cells, and that this defect is probably due to a direct impact of the mutation on these cells.