Figure 5
From: Involvement of cecropin B in the formation of the Aedes aegypti mosquito cuticle
Knockdown of AaPPO 3 in Ae. aegypti pupae leads to high pupal mortality and the emergence of deformed adult. (a) The cumulative mortality rates (%) of uninjected control (blue line), GFP dsRNA-injected control (red line), AaPPO 3 dsRNA-injected (green line) Ae. aegypti pupae at various times after injection. P< 0.5: <0.5 hr after injection. 24–120: 24–120 hrs after larval-pupal ecdysis. Each group consisted of 20 pupae in one experiment and 10 replicates were conducted. The range bars indicate the standard deviations of means. (b) An adult mosquito unable to detach from exuvia of an AaPPO 3 dsRNA-injected pupa. (c) An adult with deformed wings and legs. Arrows (↑) indicate curved wings and arrow heads (▲) indicate curved legs. (d) An injection control mosquito. (e) Ultrastructural observations of the pharate adult cuticle in the uninjected control, GFP dsRNA-injected control and AaPPO 3 dsRNA-injected Ae. aegypti pupae. Edc: epidermal cell, aenv: pharate adult envelope, aepi: pharate adult epicuticle, aexo: pharate adult exocuticle. At 12 hrs after injection, the pharate adult envelope began to be deposited on the epidermal cells in uninjected control and GFP dsRNA-injected control mosquitoes, whilst the deposition of the pharate adult cuticle envelope was not observed in the AaPPO 3 dsRNA-injected pupae. At 24 hrs after larval-pupal ecdysis, the envelope of the pharate adult cuticle was deposited in the uninjected control and GFP dsRNA-injected control mosquitoes, whilst the pharate adult envelope was amorphous, containing numerous irregular granule-like particles, in the AaPPO 3 dsRNA-injected mosquitoes. At 36 hrs after injection, 4-laminated exocuticle was present in uninjected control and GFP dsRNA-injected control pupae, with the chitin microfibrils being arranged in a helicoidal pattern. By way of contrast, only an 1-laminated exocuticle was present in the AaPPO 3 dsRNA-injected pupae with the helicoidal pattern of the chitin microfibrils being disorganized. The boxed figures are higher magnifications of the pharate adult exocuticle showing the helicoidal pattern of chitin microfibrils. Uncropped images are shown in Supplementary Figure S3.
