Two major allelic forms of myosin light chain-1 in strains of normal and dystrophic chickens.

Evidence is presented from electrophoresis and peptide-mapping for the existence of two major allelic forms of myosin light chain-1 in the fast white muscle fibers of domestic chickens. One form predominates in birds of White Leghorn stock, the other in birds of New Hampshire Red stock. The two light chain-1 forms were invariant during development. Variability was not detected in light chains-2 or -3. The distribution of the two forms in two strains homozygous for the am gene for muscular dystrophy--Connecticut dystrophic and line 413--and their controls, White Leghorn and line 412, respectively, while clearly unrelated to avian dystrophy, emphasizes the heterogeneity in background genes of these non-inbred lines and indicates caution in their use in studies of avian dystrophy.