Influence of spinal cord stimulation upon myosin light chain and tropomyosin subunit expression in a fast muscle (posterior latissimus dorsi) of the chick embryo

Abstract

Latissimus dorsi muscles of the chick consist of a slow (ALD) and a fast (PLD) muscle. The influence of chronic spinal cord stimulation in the chick embryo upon the expression of myosin light chains and tropomyosin subunits was investigated. Early in development the two muscles exhibited the same ratio of alpha- and beta-tropomyosin subunits. Later, in the slow muscle the ratio beta:alpha decreased and in chicken the amounts of the two components were about the same. In the fast muscle, the alpha-subunit increased and reached 66% in young chicken. In the fast muscle, the alpha-subunit increased and reached 66% in young chicken. In the In the early stages of embryonic development, both muscles accumulated slow and fast light chains. However, in ALD the amount of slow light chains was greater than that of fast light chains and the reverse was observed in PLD muscle. Later during development, the slow components decreased in PLD while the fast components increased; the reverse was observed in ALD muscle. The fast myosin LC3f has been detected in 18-day-old embryonic PLD. Chronic spinal cord stimulation at a low rhythm was performed from day 10 of embryonic development to day 15 or 16. In both muscles from spinal cord-stimulated embryos, the beta-tropomyosin subunit was lower than in control embryos. In ALD, the pattern of light chains was unaffected by chronic stimulation while in PLD muscle the slow and fast components were modified. In particular the ratio LCs:LCf was increased in spinal cord-stimulated embryos with regard to controls.

Chronic stimulation accelerates functional recovery of immobilized soleus muscles of the rabbit

“…Natural recovery for 4 weeks produced similar fibre type proportions to those of the stimulated group. This ability of low-frequency chronic stimulation to accelerate the acquisition of slow myosin has also been demonstrated in developing avian fast muscle (Gardahaut, Rouaud, Renaud & Ledouarin, 1985) and when adult fast muscle regenerates following Marcaine-induced degeneration (Rosenblatt, Kuzon, Houston, McKee & Plyley, 1988).…”

Transition from Non-Muscle to Muscle Myosin Light Chains in Chick Embryo Development

“…2, lane e), there are six light chains, three of which comigrate with the adult light chains of the fast type (16,000, 18,000 and 25,000) and two comigrate with the slow type 20,000 and 27,000. This pat tern is not an unusual one in embryonic muscle, in which, as many authors have shown [12,13], there are both the fast and slow light chains, and only at the time of birth does the type of innervation determine the terminal differentiation into fast and slow fibers [14], It is interesting that, in our extracts of 13-and 42-stage embryos, traces of another light chain were present, a 15,000 chain. The results reported here suggest that the appearance of myosin light chain is developmentally regulated, changing from a non-muscle to a muscle type during the dif ferentiation of the myotome.…”

Developmental changes in myosin isoforms from slow and fast latissimus dorsi muscles in the chicken

“…With respect to the peptide map of MHC of each isomyosin, the two isoforms SM, and SM, identified in the embryonic ALD muscle are indistinguishable from those expressed during neonatal and adult stages [19]. However, in terms of MLC composition, embryonic and neonatal myosins are different from adult myosins [9,10,11,21,241. While the early embryonic ALD contains fast MLC in large amounts (40% of the total MLC), fast MLC are progressively replaced by slow MLC, so that in the ALD muscle of 2-day-old chicken fast MLC represent only 8 % of the total MLC [lo].…”

“…Slow-tonic and fast-twitch muscles in adult chicken contain both slow and fast myosin isoforms, characterized by their mobilities on native gel electrophoresis [I, 151, their light chain subunits [I61 and their heavy chain components [ I , 2,4,18,251. Changes in myosin light chain subunits during muscle development have been extensively studied (9, 10,11,21,24,261. Moreover, in avian fast pectoralis muscle, a developmentally regulated transition involving a heavychain sequential expression has been described [5, 6, 18, 25, 301. * To whom offprint requests should be sent The developmental changes in native myosin isoforms in avian skeletal muscles have been incompletely investigated.…”