Differentiation in cultures derived from embryonic chicken muscle: I. Muscle-specific enzyme changes before fusion in EGTA-synchronized cultures

摘要: Abstract It is known that myoblast fusion fails to occur in cultures containing EGTA (a calcium-specific chelator) but occurs very rapidly after medium replaced with standard high-calcium medium. On the basis of a careful analysis time course switched from medium, it proposed this method synchronization be used routinely studies timing different processes during vitro myogenesis. The kinetics accumulation total enzyme activity for creatine kinase and fructose diphosphate aldolase indicate increases characteristic terminal muscle differentiation begin prior experimentally imposed onset EGTA-synchronized cultures. Additionally, M-creatine subunits, also typical differentiation, shown by microcomplement fixation before switch Creatine isoenzyme patterns show transition B- M-subunit-containing kinases not Like EGTA, 5-bromodeoxyuridine (BrdUrd) reversibly prevents fusion. By adding BrdUrd sequences cell cultures, they act at stages Cells cultured 23 69 hr plating fused when BrdUrd. In reverse experiment, which preceded no occurred. Parallel experiments 5-fluorodeoxyuridine suggest division necessary inhibitory effect BrdUrd, EGTA; consistent observed switching These data strongly support model myogenesis two (one BrdUrd-sensitive, other EGTA-sensitive) sequentially. first process, myogenic cells give rise capable producing molecules (terminal) skeletal including both those required specific isoenzymes. second itself, can presence or absence division.