Comparative expression analysis of the neurogenins in Xenopus tropicalis and Xenopus laevis.

The Neurogenin (Ngn 1-3) family of proneural basic helix-loop-helix (bHLH) transcription factors are key regulators of vertebrate neurogenesis. In the developing vertebrate nervous system, the Ngns are essential for the commitment to a neuronal fate and participate in the specification of neuronal cell-type identity. Xenopus laevis is widely used as a model system to study the early events of vertebrate neurogenesis, however, only Ngnr-1, which is most closely related to the mammalian Ngn2, has been described and characterized. Presently, we describe a comparative expression analysis of the Ngn1-3 in X. tropicalis and X. laevis embryos. The Xenopus Ngns are present in overlapping, as well as unique regions of the nervous system starting at gastrula stages, suggesting distinct roles for this important family of transcriptional factors in the establishment of the amphibian nervous system.