Fig. 4.

IFM-mediated immune response is essential for survival upon bacterial infection. (A,A′) Expression of UH3-Gal4 is restricted to IFMs in 2-day-old adults. Pattern of expression was visualized with UAS-GFP as a reporter. Yellow dotted line represents the body outline of the fly. White asterisks represent the dorsal longitudinal muscles and arrowheads indicate the dorso-ventral muscles, which together constitute the IFM. Also see Fig. S4. (B,C) Survival of male flies (n>50) infected with (B) Salmonella and (C) Bacillus subtilis. A log-rank test was done for estimating the significance of the survival curves. (B) Salmonella infected versus uninfected: UH3-Gal4/+ (Gal4 control), P=0.2207; Rel-RNAi/+ (UAS control), P=0.0640; UH3>Rel-RNAi (test), P<0.0001. Test versus infected Gal4 control, P=0.0003. Test versus infected UAS control, P=0.0009. (C) Bacillus infected versus uninfected: All fly strains, P<0.0001. Test (UH3>Dif-RNAi) versus infected Gal4 control (UH3-Gal4/+), P=0.0381. Test versus infected UAS control (Dif-RNAi/+),  P=0.0046. Solid lines, infected flies; dashed lines, uninfected controls; KD, knockdown; U, uninfected; I, infected, (B′,B″,C′,C″) AMP gene induction in the IFMs upon infection as tested by qRT-PCR of tissues isolated at 6 hpi. Induction of (B′) Diptericin and (B″) Drosocin was entirely lost in flies with altered IFM-Imd signaling. Similarly increased expression of (C′) Drosomycin and (C″) Metchnikowin was entirely lost in flies with altered IFM-Toll signaling. The values represented are mean±s.e.m. of three replicates. *, significant difference in expression of infected versus uninfected. ns, P>0.05; ***P<0.0001.