Molecular and functional identification of tyrosine hydroxylase in the yellow fever mosquito, Aedes aegypti

Aedes aegypti, an arthropod vector that transmits arboviral infectious diseases via blood feeding, has garnered significant attention. However, the in vitro biochemical activity of tyrosine hydroxylase (TH) in Ae. aegypti remains to be confirmed, and the functional role of this enzyme in mosquito has yet to be thoroughly elucidated. TH is a rate-limiting enzyme in the tyrosine metabolic pathway. Here, we identified the sequence and biochemical activity of TH in the mosquito, Aedes aegypti. To investigate the biological function of TH in the development of Ae. aegypti, RNA interference was used in the larvae and adults of Ae. Aegypti. The larvae were fed with chitosan-coated double stranded (ds) Ae. aegypti TH (AeTH) and adult mosquitoes were microinjected with dsAeTH. The number of pupae developed was decreased after AeTH knockdown in larvae, and the number of eggs laid, egg hatching rate, and blood intake of adult mosquitoes after AeTH knockdown were also decreased. The unhatched eggs laid had no normal larvae inside. The results here suggest that AeTH is involved in pupation and affects the normal development and fertility of the adults. The expression levels of melanization- and immune-related genes were examined. The results revealed that TH significantly affected bothmelanization and immune pathways. Collectively, these findings deepen our understanding of the functional role of TH in mosquitoes.