Mosquito Midgut Histology and Permeability

Forty-eight hour post blood meal mosquito abdomens were fixed and sectioned as described above [66 (link)]. Samples were sectioned at 5 μm, stained with hematoxylin and eosin (H&E) (Huntz Enterprises Inc., China) and Periodic Acid Schiff (PAS) (Sigma-Aldrich, China) according to the manufacturer’s protocol. Slides were hard mounted using Canada balsam (ChemsWorth). Slides were viewed using bright field illumination on a Nikon ECLIPSE IVi microscope connected to a Nikon DIGITAL SIGHT DS-U3 digital camera. Four days post dsRNA treatment A. stephensi were fed with blood meal supplemented with 500 kDa FITC-labeled dextran molecules (2.5mg/ml blood)(Sigma) which were filtered using PD MiniTrap Sephadex G10 columns (GE Healthcare) as described [27 (link)]. Forty eight hours post-feeding, midguts were dissected and FITC signal observed using a Zeiss, LSM710 confocal microscope connected to a Nikon DIGITAL SIGHT DS-U3 digital camera. Expression of 4 PM genes was analyzed 24 hr and 48 hr post blood meal using primers targeting peritrophin1(ASTE010406), peritrophin14 (ASTE009456), 2 chitinases, herein named chitinaseA (ASTE005630) and chitinaseB (ASTE000328) (S1 Table).