Nitric oxide is a pleiotropic free radical that in insects plays an essential role in fighting infection. Nitric oxide is produced via the oxidation of L-Arginine to L-Citrulline in a reaction catalyzed by nitric oxide synthase, and in insects, one of the major producers of this enzyme is the hemocytes. In mosquitoes, chemically inhibiting the production of nitric oxide hinders the antibacterial and antimalarial response. In vertebrate animals, nitric oxide has immune properties but it is also a vasodilator and heartbeat modulator. These functions appear to be shared in some insects. Focusing on the mosquito Anopheles gambiae as the study system, this presentation will detail how a systemic bacterial infection induces the production of nitric oxide by periostial hemocytes that reside on the surface of the heart, which reduces the heart rate and alters the proportional directionality of heart contractions. These data provide new insights into the functional integration of the immune and circulatory systems of mosquitoes during the fight against bacterial infections.
