Figure 3. Effect of CS exposure on terminal cells of 3rd instar larvae. Representative terminal cells of the dorsal branch in the third segment of Drosophila L3 larvae, where GFP was expressed under UAS control with a terminal cell specific GAL4 driver to visualize these tracheal terminal cells (A). For the analyses of the branching pattern, only one of the two terminal cells was analysed per replicate (A). Tracing of Type2, type3 and type4 branches was done with NeuronJ (B, B’). (C) The number of Type II branches was evaluated in control animals (black, those treated for 2 days with CS (red) and those treated for 3days with CS (violet). (D) as described for C, but focused on type III branches. Total lengths of type II (E) and type III (F) branches were measured. Also, the more frequent the smoke exposure, the shorter the length of Type II and III branches. To test for physiological changes after prolonged CS exposure, we analyzed the flight response of L3 larvae to reduced oxygen conditions. The percentage of larvae leaving the medium, after decreasing the concentration of O2 to 2.5-4%, was calculated. (* means p<0.05, ** means p<0.01, *** means, p<0.005).