understand the phenotypes resulting from mutations in developmentally important
genes.
Many of the pathways that regulate apoptosis in flies are similar to those in
mammalian systems. In both organisms, DNA damage induces p53-dependent
apoptosis, and steroid hormones activate both apoptotic and differentiation
pathways. The available genetics in flies allows candidate target genes to be tested for
importance. In the future, rapid new strategies for producing knockouts should allow
even multiple targets to be tested together. The study of apoptosis during Drosophila
metamorphosis will produce a better understanding of how different tissues respond
differently to the same hormonal signal. Some of this specificity is probably due to
the impact of other signaling pathways on the cell. It is probable that similar processes
regulate specificity in response to hormones in other system.
Our understanding of apoptosis during animal development is far from complete.
Determining which cells die, and how these patterns of death are controlled will be
a critical contribution of in vivo models such as flies and worms. The problem of how
perturbations in development are compensated by altered patterns of apoptosis is a
fascinating area for future work.
APOPTOSIS IN DROSOPHILA 197