Hoxb1b affects nucleosome organization at the hoxb1a promoter. A. Diagram illustrating location of primers used for nucleosome scanning across the hoxb1a locus. B-D. Overlay of nucleosome profiles at the hoxb1a promoter for 4hpf versus 9hpf wild type embryos (B), 4hpf wild type versus 9hpf hoxb1b−/− embryos (C) and 9hpf wild type versus 9hpf hoxb1b−/− embryos (D). The −3, −2, −1, +1 and +2 nucleosomes are labeled in (B). Green circles indicate locations where changes in nucleosome organization are statistically significant (p < 0.05) while arrowheads point to Site 1 (green arrowhead) and Site 2 (red arrowhead) discussed in the text. Error bars represent standard error of three biological replicates. Red region on horizontal axis indicates approximate location of Pbx/Meis/Hox binding sites.