Fig. 9. Analysis of the interaction between her7 and her1 on segmentation and cyclic gene expression in wild-type and beamter embryos. The myotome boundaries of the trunk, marked by twitchin expression, and the sclerotome, marked by twist in the tail, are shown in 26 hpf embryos in lateral view, anterior towards the left and dorsal upwards (A-D, W,X and E,F, respectively). The expression of segmental and cyclic genes in the presomitic mesoderm and trunk somites are shown in dorsal view after flat mounting with anterior upwards for embryos at 14 hpf (10 somites) (G-P,U,V) and at three somites (T). Expression of dlc is shown in whole-mount embryos from 80% epiboly to bud stage in a dorsovegetal oblique view (Q-S). Arrows indicate localized defects and brackets indicate the extent of larger regions of abnormalities. Scale bar in A: 250 µm for A-D,W,X. (A) Uninjected wild-type control. (B) Wild-type injected with 2.5 ng/µl of both her1m1 and her7m2, (C) 5 ng/µl her1m1 or (D) 5 ng/µl her7m2. Scale bar in E: 50 µm. In each panel (G-V), a pair of embryos is shown, with uninjected on the left and injected with 2.5 ng/µl of both her1m1 and her7m2 on the right, indicated with + (or top and bottom respectively in Q-S). Expression of myod (G), notch5 (H), fgf8 (I), lfng (J) notch1a (K), papc (L), mespa (M), mespb (N), her1 (O), her7 (P), dlc (Q-U) and dld (V). In Q-S, arrowheads indicate regions of the PSM that exhibit clear stripe and interstripe (i.e. segmental) patterns in control, but not in injected embryos, and the diffuse nature of the anterior-most expression domain in injected embryos is highlighted with asterisks in R,S. (W) Uninjected bea control and (X) bea injected with 2.5 ng/µl of both her1m1 and her7m2. (Y) Histogram comparing the position of the anterior limit of segmental defects in 26 hpf bea controls, and wild type and bea mutants injected with 2.5 ng/µl of both her1m1 and her7m2.