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

Abstract

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.

The myosin alkali light chain proteins and their genes

“…Determination of the distribution of the myosin alkali light chain genes within the genome was not possible before cloned copies of the mRNAs became available due to the absence of identified allelic isoforms of these proteins, except in the chicken where electrophoretic variants of MLC1F have been used to show that the MLC1F/MLC3F gene is unlinked to the 'am' gene for muscular dystrophy (Rushbrook et al, 1982;Rushbrook & Somes, 1985). The absence of allelic variants associated with disease or mutant phenotypes has excluded classical genetic approaches, and somatic cell hybridization techniques relating chromosome retention and loss to phenotypic expression are complicated by the multinucleate nature of the myotube cell and by the fact that expression of contractile proteins is suppressed in cell hybrids (see Carlsson et al, 1974) although it can be seen in heterokaryons (Wright, 1982;Blau et al, 1983).…”

Variability in the amino-terminus of myosin light chain-1

“…Identification of Myosins Homozygous for the Type I, II, and III LCl Variants for Use in Structural Studies. SDS gel electrophoresis readily identified myosins homozygous for type I or type II LCl in the commercial chicken population and in strains available from the University of California at Davis (Rushbrook et al, 1982). On SDS gels the type III/III homozygote, however, closely resembled the type I/III heterozygote, requiring a comparison of the type shown in Figure 1 for unequivocal identification prior to structural studies.…”

“…Numerous chicken strains were used during the study. White Leghorn, Rhode Island Red, New Hampshire (normal line 412 and dystrophic line 413), Connecticut dystrophic, and birds bred for a genetic study were obtained from sources described previously (Rushbrook et al, 1982;Rushbrook & Somes, 1985). Inbred White Leghorn (normal line 03 and dystrophic line 433) and inbred New Hampshire (normal line 400 and dystrophic line 443) birds were obtained from the University of California at Davis.…”

“…SDS Gel Electrophoresis and SDS Gel Peptide Mapping. SDS gel electrophoresis and peptide mapping (using Staphylococcus aureus V8 protease) were carried out as described previously (Rushbrook et al, 1982).…”

“…We have identified three forms of myosin light chain 1 (LC1), type I, type II, and type III, in avian fast white muscle fibers (Rushbrook et al, 1982;Rushbrook & Somes, 1985).…”