A fluorescent toolkit for spatiotemporal tracking of apoptotic cells in living Drosophila tissues

Far from being passive, apoptotic cells influence their environment. For instance, they promote tissue folding, myoblast fusion and modulate tumor growth. Understanding the role of apoptotic cells necessitates their efficient tracking within living tissues, a task which is currently challenging. In order to easily spot apoptotic cells in developing Drosophila tissues, we generated a series of fly lines expressing different fluorescent sensors of caspase activity. We show that three of these reporters (GFP, Cerulean and Venus derived molecules) are detected specifically in apoptotic cells and throughout the whole process of programmed cell death. These reporters allow the specific visualization of apoptotic cells directly within living tissues, without any post-acquisition processing. They overcome the limitations of other apoptosis detection methods developed so far and notably, they can be combined with any kind of fluorophore.