Adipokinetic hormones in the African malaria mosquito, Anopheles gambiae: identification and expression of genes for two peptides and a putative receptor.

Adipokinetic hormones (AKHs) are neuropeptides that mobilize stored fuels for flight in insects, and thus, may regulate flight by mosquitoes that transmit pathogens of human diseases. Our study of AKHs in the African malaria mosquito, Anopheles gambiae, identified and characterized the expression of genes encoding two AKHs, Anoga-AKH-I (pQLFTPAWa) and Anoga-AKH-II (pQVTFSRDWNAa), and a putative homolog for an AKH G-protein coupled receptor. Gene transcripts for both Anoga-AKHs and the AKH receptor were present in eggs, larvae, pupae, and adults of An. gambiae. In females, these transcripts were apparent in heads and thoraces for up to 72 h after blood or sugar feeding, as revealed by RT-PCR. With immunocytochemistry, a cluster of neurosecretory cells posterior to the corpus cardiacum and specific cells in the brain and thoracic ganglia of females were immunostained with an AKH antibody, which recognizes both Anoga-AKHs. Accordingly, Anoga-AKH-I was detected in extracts of female heads and thoraces by HPLC and an AKH radioimmunoassay, whereas Anoga-AKH-II was detected only in heads.