Characterization of four Toll related genes during development and immune responses in Anopheles gambiae

Toll-like receptors (TLRs) are a group of evolutionary conserved proteins with diverse biological functions. In Drosophila melanogaster, Toll protein plays an important role in pattern formation in embryogenesis and in antimicrobial immunity in larvae and adults. In insects, Toll and two other related proteins, Tehao and 18-wheeler have been shown to participate in the activation of the innate immune responses to fungal and bacterial pathogens. In this paper we report the cloning and characterization of four TLR gene from malaria vector mosquito Anopheles gambiae, AgToll, AgToll6, AgTrex, and AgToll9, orthologues of DmToll, DmToll6, DmTollo (Toll8) and DmToll9 (CG5528) in Drosophila melanogaster. The expression profiles of these genes during development, in different adult tissues and after immune challenge were examined. As expected for the orthologue of Drosophila Toll, AgToll was found to be expressed highly in the ovary and may play a role in pattern formation during embryogenesis. AgToll9, surprisingly, was found to be highly expressed in the adult gut. The potential roles of these genes in development and immunity were discussed.