Research Highlight Neither Too Much Nor Too Little: Reactive Oxygen Species Levels Regulate Drosophila Hematopoiesis

Owing to their fast diffusion, reactive oxygen species (ROS) are important tissue signalling components. High levels of ROS are gen-erally considered as deleterious to cells. In vivo experiments in the Drosophila hematopoietic organ now challenge this view by showing that high ROS levels are intrinsically required to prime myeloid-like progenitors to differentiate. Reactive Oxygen Species (ROS) encom-pass a variety of diverse chemical products including superoxide anions, hydroxyl rad-icals and hydrogen peroxides. Some ROS, such as superoxide or hydroxyl radicals are extremely unstable whereas some others, like hydrogen peroxide are diffusi-ble and long-lived. These different radical species can either be generated exogen-ously or produced intra-cellularly by mito-chondria. The control of overall ROS levels is crucial to maintain physiologica