Fig. 1. Hes6 transcription is detectable in developing muscle in mouse embryos and C2C12 myoblasts in culture. ³⁵S-labelled in situ hybridisation for Hes6 mRNA on parasaggital sections of mouse embryos. (A,B) Day 13 p.c. embryo, Hes6 mRNA is present in the developing somites. (C,D) Day 16 p.c. embryo. Hes6 mRNA is expressed in the developing muscles in the forelimb; h, humerus. (E,F) Skeletal muscle (panniculus carnosus) from an adult mouse. Hes6 mRNA is undetectable. (G) Northern blot analysis of Hes6 expression in adult mouse tissues, compared with a actin control probe that also reacts with ß actin. The difference in the actin hybridisation in the heart and skeletal muscle lanes reflects tissue specific differences in the levels of and ß actin. Each lane was loaded with 2 µg of mRNA. Hes6 mRNA runs at 1.4 kb. (H) Hes6 transcription during C2C12 myoblast differentiation in vitro. C2C12 myoblasts were placed into differentiation medium for 0-4 days. RNA was isolated and analysed by northern blot. Each lane was loaded with 20 µg total RNA. The blot was also probed for myogenin, to confirm induction of differentiation and stained with Methylene Blue (Me blue) to reveal 18 S RNA. Result shown is typical of three independent experiments.