Article Abstract:
Retinal axons ingrowing from the Drosophila's developing eye regulate the development of the brain's visual centers. Final cell division and neural differentiation are triggered by the precursors of the synaptic partners of retinal axons arriving at the lamina, the eye's first optic ganglion. The role of the hedgehog gene in this process is studied. Results indicate that the retinal axons transmit the hedgehog, which then acts as the inductive signal in the brain. Moreover, it is shown that the hedgehog participates in the first of two retinal axon-mediated steps in the assembly of lamina synaptic cartridges.
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Article Abstract:
Notch1, a mammalian homolog of the Drosophila melanogaster Notch gene, is asymmetrically localized within dividing progenitor cells and inherited differentially following asymmetric divisions. Asymmetric divisions during mammalian neurogenesis produce basal daughter cells which behave like young migratory neurons and apical daughters that remain within the proliferative zone. Notch1 immunoreactivity prevails asymmetrically in mitotic cells, with Notch1 inherited selectively by the basal daughter cells of horizontal divisions.
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Article Abstract:
Adult transgenic mice were used to examine the role of neural growth-associated protein GAP-43 in the regulation of neurite outgrowth in adult nervous system. Mice that expressed the protein exhibited nerve sprouting at the neuromuscular junction and in hippocampal mossy fibers. Mice that overexpressed GAP-43 showed lesion-induced nerve sprouting and terminal arborization during reinnervation, while mice with mutant GAP-43 showed reduced nerve sprouting activity.
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