Fig. 1. Identification of a Xath5 regulatory fragment that functions in vivo. (A) The pG1X5 construct contains 3.3 kb of 5' Xath5a genomic DNA cloned into the promoterless vector pG1 with a GFP reporter. The TATAA element is at –226 bp, the putative transcription start site is at –205 bp and the translation start site is at +1 bp. (B) In situ hybridization showing that endogenous Xath5 mRNA is expressed in the retina, the pineal gland (arrowhead), and the olfactory placodes (arrows) of a stage 28 embryo (frontal view). (C,D) Frontal and lateral views of a stage 28 transgenic pG1X5 embryo showing expression of the transgene in the same tissues as the endogenous Xath5 mRNA (compare with B).