Figure 2

MD6.0-lacZ contains elements differentially regulated during differentiation. Primary mouse myoblasts were transiently transfected with MyoD-lacZ reporter constructs and expression quantified relative to control TK-luciferase, as a control for transfection efficiency. Luciferase control plasmids showed no overall change in expression between 1 and 4 days. A, Schematic representation of the constructs used. B, MyoD reporter activity after 1 day in differentiating conditions. β-galactosidase activity in different MyoD reporter plasmids contained within the 6 kb region upstream of MyoD. C, The change in reporter activity at 4 days compared to 1 day in differentiating conditions. Expression from the DRR element increases during differentiation. D, The addition of KCl to reduce electrical activity during the final day of culture inhibits the changes in reporter activity seen during differentiation.