Larval hematopoietic organs of multiple species show effector caspase activity and DNA damage response.

Macrophages are present in various forms throughout metazoans and play conserved roles in phagocytosis, immunity, and tissue homeostasis. In s larval hematopoietic organ, the lymph gland, transient caspase-mediated activation of caspase-activated DNase triggers the DNA damage response (DDR), which is crucial for macrophage-type cell differentiation. Here, we report that other species having different-sized mature lymph glands show effector caspase activity and DDR similar to those in , indicating that the developmental mechanism regulating phagocytic macrophage differentiation is conserved in different species of .