Figure 1 - Secretion of radioactive protein as a function of larval age. The radioactive protein was collected over a period of 1 h after the injection of 1 Ál of [3H]-Leu solution into larvae at different ages (E1 to E7+10h). The radioactive material was collected on fiberglass filters at 5 to 15 min, 15 to 20 min, 20 to 30 min and 30 to 60 min after injection of the radioactive precursor. The horizontal bars in Figure 1A (top) show the times during larval development when DNA puffs are expanded. The cumulative radioactive secretion obtained during a period of 1 h is reported at the bottom as a function of larval age. The ages of larvae are expressed on the abscissa as hours from the first age studied and as eyespot patterns. Figure 1B shows the kinetics of secretion for the same experiments. Each result, in cpm, is the mean of 3 independent experiments.