Fig. 4. Western blot analysis of VM32E and VM26A.2 vitelline membrane proteins. Staged egg chambers (stages 9-14) and ovaries (Ov) were processed as described in Materials and Methods. The pellet phase (P) contains the proteins integrated into the eggshell whereas the supernatant phase (S) contains those not yet incorporated into the eggshell. The VM32E protein was detected using the anti-CVM32E antibody, whereas the VM26A.2 protein was detected by anti-VMP antibody. (A) By the end of oogenesis (stages 13-14), a significant reduction of the VM32E signal is detected compared with the earlier stages (10-12). (B) At stage 10, the VM26A.2 protein is detected mainly in the pellet phase. At stage 14, this protein is still fully releasable from the pellet phase. (C) Stage 14 egg chambers and ovaries were extracted in presence of 2% SDS.