<b>CHANGES IN THE MOLECULAR SIZE OF CONNECTIN, AN ELASTIC PROTEIN, IN CHICKEN SKELETAL MUSCLE DURING EMBRYONIC AND NEONATAL </b><b>DEVELOPMENT </b>

Abstract

By sodium dodecyl sulfate (SDS)-gel electrophoresis, several types of connectin, an elastic protein of vertebrate skeletal muscle, different in their electrophoretic mobility, were detected in embryonic, neonatal and adult skeletal muscles of the chicken: embryonic, α, β, β’, neonatal α, and adult α, β, β’. The relative mobility was slower in the following order: embryonic α<neonatal α<adult α<embryonic β<embryonic β’=adult β<adult β’. As revealed by fluorescent immunoblots, embryonic types of connectin were reactive with polyclonal antibodies against adult β-connectin which is the proteolytic product of adult α-connectin. Embryonic and neonatal α-connectins were found from day 7 of incubation to day 3 posthatch, and from the day of hatch to day 7 posthatch, respectively. Adult α-connectin appeared on day 5 after hatch. Embryonic β-connectin was present until day 3 posthatch and adult β’-connectin was detected from day 5 after hatch on. Embryonic β’-and/or adult β-connectins were present from the 7th day of incubation and thereafter. The two types of connectin were not distinguishable by SDS-gel electrophoresis.