Autoradiographic studies of RNA and DNA synthesis during myogenesis in cultures of human, chick and rat muscle

Abstract

RNA synthesis was studied by the capacity to incorporate [ 3H]-uridine, and was found to occur in the mononucleate cells, multinucleate myoblasts and myotubes in cultures of human, chick and rat muscle. Species differences were observed in the comparative rate of incorporation by the multinucleate and mononucleate cells. In human cultures the multinucleates were labelled more than the mononucleates, in chick cultures they were labelled the same, while in cultures of rat muscle the multinucleates were labelled less than the mononucleates. No difference in RNA synthesis was found in cultures from normal and diseased human muscle, suggesting that diseased human muscle in culture is capable of normal RNA metabolism. DNA synthesis did not occur in multinucleate myoblasts and myotubes of either human or chick muscle in culture. Therefore, once the mononucleate myoblasts have fused and differentiated, they are no longer capable of DNA synthesis.