Functional analysis of two chitin synthase genes in African malaria mosquito, Anopheles gambiae

Chitin synthase (CHS) is an important enzyme in insects and other chitin-containing organisms. Chitin synthase is encoded by two genes in insects, chitin synthase 1 and chitin synthase 2. Current knowledge indicated that chitin synthase 1 is expressed in cuticle and trachea, while chitin synthase 2 is exclusively expressed in the gut of insects. Here we report the functional analysis of two chitin synthase (AgCHS1 and AgCHS2) genes in African malaria mosquito, Anopheles gambiae. Both AgCHS1 and AgCHS2 can be repressed by feeding of the mosquito larvae with its own dsRNA, indicating the systemic property of RNAi in mosquito larvae. Repression of AgCHS1 significantly reduced the chitin content in mosquito larvae. Silencing of AgCHS2 synergized the effect of DTT and calcoflour effect on mosquito larvae by increasing the peritrophic membrane permeability.

Key words: chitin synthase, Anopheles gambiae, RNA interference, chitin, peritrophic membrane