Figure 4

Comparison of GRS1 -dependent ß-galactosidase activity with endogenous Grem1 transcripts during limb bud development. (A) ECR browser alignment of the 9 kb GRS1 region containing HMCO1. The mouse genome (mm9) is used as reference genome. The conservation threshold was set ≥74% identity over ≥100 bp (see legend to Figure 1A for details). Above the sequence alignment, a schematic representation of the GRS1-ßglob-LacZ transgene is shown. GBR: GLI binding region [32]; GLI motifs: consensus GLI binding sites identified by in silico analysis. (B C) Distribution of ß-galactosidase activity in forelimb buds of heterozygous embryos of the tg10 (10 copies, GRS1^tg10/+, B) and the tg2 (2 copies, GRS1^tg2/+, C) mouse strains between embryonic days E9.5 to E12. (D) Distribution of endogenous Grem1 transcript in the corresponding stages of wild-type forelimb buds. Arrowheads at E10.5 point to the ß-galactosidase activity and Grem1 transcript in the posterior limb bud mesenchyme. The brackets at E11.5 serve to indicate the distance between the ß-galactosidase activity (B C) or Grem1 expression domain (D) and the AER. Note that ß-galactosidase activity fails to expand distally in comparison to the Grem1 domain.