E75 and the Broad-Complex. The target genes control the late genes in order to prompt biological changes associated with each SR 7826 ecdysone pulse. To assess whether ecdysone signaling is affected in ceng1A mutants, we analysed expression of the ecdysone inducible genes E75B and E74A, as well as PTTH expression from the second instar stage to pupariation. RQ 00203078 Whereas we could not detect significant changes in PTTH expression between ceng1A mutants and controls, we found, however, a reduced induction of the ecdysone targets E75B and E74A. Induction of E75B and E74A seem to occur at the correct time points, however, the induction is lower than in the control aninmals. At 72 hours after egg lay E75B induction is only 0.5 fold compared to the controls. One peak is even missing. In 76% of the time points, expression of E75B is reduced in ceng1A mutants compared to the controls. Comparison of growth rate and larval stage with ecdysone peaks shows a clear correlation of ecdysone peaks and plateau phases in growth of the control animals. At 72 hours and 88 hours after egg lay those coincide with L2/L3 or L3/pupae transition respectively. In the mutants plateau phases in growth e.g. at 72 hours does not coincide with the ecdysone peaks and stage transition. Reduced growth rate as well as transition of larval stages is delayed. In contrast, the duration of the third instar stage is not altered, indicating that the main defect is in L2 larval stage. Of note, similar developmental delay phenotypes are found when ecdysone signaling is decreased. Mutants of the ecdysone target E75A e.g. are stuck in 2nd instar larval stage and pupariate without molting into third instar larvae. Layalle et al. showed previously that via the nutrient sensor AMPK, TOR signaling couples nutrition to developmental timing by modifying the timing of ecdysone peaks in the prothoracic gland in a nutrition-dependent manner. However, we didn��t find an effect of Ceng1A on AMPK phosphorylation. Moreover, even though delayed in timing, ceng1A mutants still respond normally to different nutrient conditions and the timing of ecdysone peaks themselves is not affected. This argues that coupling of nutritional status to timing is still intact, indicating that TOR signaling is not affected in the mutants. Nor did we find in ceng1A mutants significant alterations of the activities of IlS components such as Akt or a change of FOXO target genes or changes in organ size.