bHLH transcription factors and neurogenesis in the zebrafish late embryonic and adult central nervous system.

Understanding the molecular mechanisms underlying adult neurogenesis are of major interest for the development of neuronal therapies. In this work we identified regions of continuing neurogenesis in the the zebrafish brain. Neurogenesis in the adult zerabfish the telencephalon shows remarkable similarities to olfactory bulb neurogenesis in rodents but in addition a new population of stem cells contributing neurons to the telencephalon proper. Two new proliferation zones have been identified in the midbrain contributing neurons to the tectum and the tegmentum. Further new bHLH transcription factors have been isolated which likely control neurogenesis or are involved in the maintenance of the neural progenitor state. Taken together we have validated the zebrafish as a model system to study adult neurogenesis and opened the way to identify the characteristics or adult neural stem cells and to assess the general molecular mechanisms of late neurogenesis