Fig. 3

CPCFC is necessary for cuticle-mediated malathion penetration resistance. A The expression profile of CPCFC in MS and MR adult flies at 3, 5, 7 and 9 days old (A3, A5, A7 and A9, n = 4). B The expression levels of CPCFC in different tissues of the MR and MS strains: pronotum (PR) cuticle, abdomen (AB) cuticle, fat body (FB), midgut (MG) and Malpighian tubule (MT). Each sample contained 20 fly-tissues of 5-day-old adult (n = 4). C Immunolocalization of CPCFC on ultrathin sections of the pronotum cuticle, showing the epicuticle (EP), exocuticle (EX), endocuticle (EN) and epidermic cells (EC). The white squares correspond to zoomed cuticular ultrastructure of (C′), (C′′), (C′′′) and (C′′′′). The black arrow indicates the 10-nm colloidal gold signal of CPCFC. (C′), (C′′) and (C′′′) The pronotum cuticular ultrastructure of EC and EN. (C′′′′) The pronotum cuticular ultrastructure of EX and EP. D Chitin-binding activity of CPCFC, showing the protein concentration in the supernatant (n = 3). E CPCFC expression levels after silencing (n = 4). F The effects of CPCFC silencing on the structure of the pronotum cuticle. CPCFC protein expression was determined by the fluorescence signal intensity over length in each sample (n = 6). G Analysis of the cuticular ultrastructure after silencing CPCFC. H Analysis of the pronotum cuticular thickness after silencing CPCFC (n = 10). Each thickness value is the mean of five randomly selected cross-sectional measurements. I The malathion penetration rate after silencing CPCFC. Each eluant contained 30 5-day-old adult flies (n = 3). J The effect of CPCFC silencing on susceptibility to malathion. Survival rate was observed at 0–3 day after malathion exposure (n = 120)