Figure 3 - Fluorographic pattern from the electrophoretic profile of extracts of salivary gland regions (S1, S3 and S2) and saliva (Sal) from larvae of different ages at the end of the fourth instar (E1, E5 and E7+6h). One Ál of [3H]-Leu solution was injected into the larvae and the salivary gland regions were processed 15 min later for SDS-PAGE and fluorography. Figure 3A shows the same samples compared with samples of saliva collected for 2 h from larvae of the same ages. The apparent molecular mass, in kDa, of the main SP is indicated on the left side of each set of samples. Figure 3B is a schematic representation of the fluorogram in Figure 3A. The height of the bars represents the relative quantities of the labelled polypeptides. MM = Apparent molecular mass in kDa.