Characterization of Npas3, a novel basic helix-loop-helix PAS gene expressed in the developing mouse nervous system

Here we describe the cloning and expression pattern of a new bHLH-PAS domai n gene, Npas3. Npas3 shares 50.2% amino acid sequence identity with Npas1 a nd a lesser similarity with other members of the bHLH-PAS domain family of transcription factors. Northern blot analysis detected Npas3 mRNA between 1 1.5 and 17.5 d.p.c. in embryonic development and exclusively in the adult b rain. Whole-mount and section in situ hybridization assays revealed express ion of Npas3 between 9.5 and 11.5 d.p.c. in the developing neural tube. In addition, Npas3 mRNA was expressed throughout the neuroepithelium of the de veloping central nervous system between 10.5 and 12.5 d.p.c. Interestingly, at 14.5 d.p.c., the expression of Npas3 mRNA became restricted to the neop allial layer of the cortex. At 12.5 d.p.c., Npas3 mRNA was evident in nonne ural tissues such as the developing dermis and mesenchyme surrounding the o tic and nasal placodes. Expression was also detected in the developing card iac valves, limb and developing kidney. (C) 1999 Elsevier Science Ireland L td. All rights reserved.