Fig. 8. Cross-species analysis of Ath5 transgene expression. (A) The proximal 600 bp of the Math5 cis-regulatory region drives weak GFP expression in the retina of transgenic frog embryos, as shown by in situ hybridization on a pG1M5-0.6 kb transgenic Xenopus embryo. (B) GFP in situ hybridization in a pG1M5-2.3 kb transgenic embryo. The 2.3 kb Math5 fragment drives strong transgene expression in the retina, cranial ganglia, midbrain and hindbrain regions in transgenic Xenopus embryos. (C) In situ hybridization on retinal sections from stage 41 pG1M5-2.3 kb transgenic embryos shows that the domain of GFP mRNA is restricted to the CMZ (bracket). (D) E13.5 whole embryo image demonstrating retinal expression of the pG1M5-2.3 kb transgene in mouse embryos at E13.5 (arrow). (E) The Xenopus 3.3 kb Xath5 transgene (pG1X5-3.3 kb) also shows retinal expression at E13.5. (F,G) Math5 is not required for expression of the pG1M5-2.3 kb transgene as equivalent fluorescence from the transgene was observed between wild-type (F) and Math5^–/– (G) embryos. Scale bar: 500 µm in D.