FREE AMINO ACIDS OF DEVELOPING SKELETAL MUSCULATURE OF NORMAL AND GENETICALLY DYSTROPHIC CHICKENS.

Summary The free amino acid patterns of leg and breast muscles were studied during the development of normal and dystrophic chickens from the 14-day-old embryo to the 2-week-old chick. Although these patterns changed with time little difference was found between muscles or strains until after hatching. An unidentified ninhydrin positive substance (CX) was present at high levels in the muscles of 18- to 20-day-old embryos and day-old chicks; CX rapidly declined in all but the dystrophic breast muscle by the time the chicks were 2 weeks of age. Its subsequent disappearance was accompanied by the appearance of serine ethanolamine phosphate, which occurs characteristically in dystrophic breast muscle. Taurine, also occurring at high levels in the embryo, remained high in dystrophic chick breast muscle. The results indicate that dystrophic chick muscle retains some embryonic properties and that this form of muscular dystrophy involves changes in muscle development.