Aquaporins in the Malpighian tubules are essential for water transport in the Yellow Fever mosquito, Aedes aegypti

Female mosquitoes require the uptake of blood for egg production and as a result, they transmit disease pathogens to humans. It is essential for mosquitoes to possess an efficient excretion system to shed excess water and sodium ions and retain nutrients from the blood. After a blood meal, females excrete excessive amounts of urine through their excretory organs, the Malpighian tubules (MT). Aquaporins (AQPs) are a family of membrane transporters that regulate the flow of water, glycerol and other small molecules across cellular membranes in both prokaryotic and eukaryotic cells. Previously, we surveyed genome databases and identified six putative AQPs in the genome of Ae. aegypti. RNAi-mediated knockdown of the MT-expressed AQPs in Ae. aegypti resulted in significantly reduced diuresis. Recently, we have confirmed that the MT-expressed AQPs function as water channels and mediate transcellular water transport in adult female Ae. aegypti. We have expressed Ae. aegypti AQPs in Xenopus laevis oocytes which has resulted in significant increase in water permeability of their cell membranes and subsequent swelling proving that these proteins are indeed water channels. Quantitative PCR and in situ hybridization assays have shown where these AQPs are located within the MTs and the level in which they are expressed during certain time points.