Aquaporin AaAQP2 protein abundance in the anal papillae of Aedes aegypti is modified by salinity

The Aedes aegypti mosquito, a viral disease vector, can complete its life cycle in breeding sites that range in salinity from ion-poor to fresh and brackish water. Fluctuations in salinity provide different challenges to larval regulation of ion and water transport. Western blots of proposed water channel A. aegypti aquaporin 2 (AaAQP2) revealed this protein is found in the osmoregulatory organs, including gastric caecae, Malpighian tubules (MTs), hindgut, and anal papillae (AP) of larvae reared in varying salinity. AaAQP2 immunolocalization in MTs shifted from apical to intracellular as salinity increased, and could imply AaAQP2 is trafficked from the cell membrane to potentially decrease MT water secretion. Protein abundance of the presumed AaAQP2 monomer in AP increased as salinity increased, however, larval survival increased when larvae with knockdown AaAQP2 in the AP were transferred to higher salinity. Results suggest AaAQP2 protein levels impact larval physiology when changes in environmental salinity occur.