Fig. 7. XHes6 and XHes6DBM upregulate myogenesis and disrupt somitogenesis. Embryos were injected in one of two cells with 2 ng of (A,D,E) XHes6, (B,F,G) XHes6DBM or (C,H,I) XHes6WRPW along with nuclear ß-gal. At stage 22, the embryos were fixed and transversely (A-C) or longitudinally (D-I) sectioned and analysed for expression of MA (red); nuclei are stained with Hoechst (blue). Transverse sections are oriented with injected side to the left. Longitudinal sections are arranged with anterior towards the left and the injected side upwards. Broken white lines indicate the outlines of the embryo, the neural tube and the notochord. Quantitative image analysis was performed and the ratio of MA-expressing areas on injected and uninjected sides analysed as described in the Materials and Methods; results are shown in J. The error bars indicate the s.e.m. P values with a two-tailed t test, comparing mean ratios on injected and uninjected sides, were 0.017 for XHes6, 0.004 for XHes6DBM and 0.33 (not significant) for XHes6WRPW. Both XHes6 and XHes6DBM cause complete disruption of somitogenesis (100% of embryos disrupted, n=26, 25 respectively), while XHes6WRPW has a minimal effect (10% of embryos disrupted, n=20). In each embryo, the ß-gal tracer was distributed both in the mesoderm and the ectoderm (data not shown)