Figure 6

Immune pathways activation induces LD accumulation in mosquito midgut cells after a blood meal.

Mosquitoes were injected with double-stranded RNA (dsRNA) for Cactus, Caspar and LacZ (a control dsRNA). 24 hours post injection mosquitoes were either maintained feeding on sugar or fed with blood. After 24 hours, midguts were dissected for RNA extraction or BODIPY 493/503 staining for visualization of LDs. (A) Schematic representation of the insect immune pathways, Toll and IMD. Red crosses represent genes that were knocked-down using RNAi, Cactus and Caspar. (B) Knock-down efficiency in the mosquito midgut injected with dsCactus (B) and dsCaspar (C) in both sugar-fed and blood-fed conditions was determined by qPCR. Gene expression is relative to tissues from dsLacZ injected mosquitoes (evidenced by the dashed line). (E–G)BODIPY staining of lipid droplets from sugar fed mosquito midguts from insects injected with dsLacZ (E), dsCactus (F) and dsCaspar (G). BODIPY staining of lipid droplets from blood fed mosquito midguts from insects injected with dsLacZ (H), dsCactus (I) and dsCaspar (J). (D) Fluorescent particle quantification from images (H–J) was performed using Analyze particles tool from ImageJ. Scale bar = 10 μm.