Tutl is required at larval stage after the completion of embryonic development. “Rescue” refers to the group of tutl23/23 mutant larvae that carry UAS-tutl transgene under control of the pan-neuronal-specific driver C155-GAL4. “Rescue+GAL80ts” refers to the group of “Rescue” larvae that also carry a temperature-sensitive GAL80 (GAL80ts) under control of tubulin promoter. GAL80 is active at 18°C, allowing it to inhibit GAL4 and thus turning off the expression of tutl transgene. At 29°C, GAL4 is inactivated, allowing GAL4 to turn on the expression of tutl transgene. Number in each bar indicates the number of larvae tested. A shift of temperature thus allowed us to turn on or turn off tutl transgene expression after the completion of embryonic development. ***p<0.005, “ns” indicates p>0.05, t-test. Error bars represent SEM.