Biologjia Online

The spatial regulation of neuorogenesis is a mysterious but crucial process in vertebrate central nervous system development. In zebrafish embryos, proneuronal domains, which produce early neurons, are separated by inter-proneuronal domains, which do not undergo neurogenesis until later in development. On p. 1375, Bae and colleagues report that the hairy- and enhancer of split-related genes her3 and her9 link positional information in the posterior neuroectoderm to the spatial regulation of neurogenesis. The expression of her3 and her9 is restricted to inter-proneuronal domains, and inhibiting either of their functions with antisense morpholinos causes the ectopic expression of proneural genes in these domains. Inhibiting both proteins' functions abolishes inter-proneuronal domain formation. Other results indicate that her3 and her9 expression is regulated by positional information in which Bmp signalling is involved. The researchers conclude that her3 and her9 spatially control neurogenesis by functioning as prepattern genes.