Figure 2. Genetic and pharmacological modulation of Nos activity alters GFAP^R79H toxicity.

Nos was overexpressed with a UAS-Nos transgene (Nos OE) and reduced with UAS-Nos RNAi lines (Nos RNAi). GFAP represents UAS-GFAP^R79H. (a) The number of TUNEL-positive cells is increased in GFAP^R79H transgenic flies with overexpression of Nos (Nos OE) and decreased with reduced expression of Nos (Nos RNAi). **P<0.0001, F=72.53, df=29; n=6 per genotype. Flies were 20 days old. Genotypes are indicated in the figure label. Driver: repo-GAL4. (b) Seizure frequency is increased with overexpression of Nos (Nos OE) and decreased with reduced expression of Nos (Nos RNAi). *P=0.0264, χ²=4.926, df=1; **P<0.0001, χ²=24.731, df=1; n>100 per genotype. Flies were 1 day old. Genotypes are indicated in the figure label. Driver: repo-GAL4. (c) The Nos inhibitor L-NAME reduces the number of TUNEL-positive cells in GFAP^R79H transgenic flies in a dose-dependent manner while D-NAME, the inactive enantiomer, shows no effect. *P<0.01, **P<0.001, F=12.41, df=27; n⩾6 per condition. Flies were 15 days old. Genotype: repo-GAL4, UAS-GFAP^R79H/+. (d) Seizure frequency is reduced with L-NAME administration, but not with D-NAME. **P<0.0001, χ²=24.987, df=1; χ²=24.083, df=1; n>100 per condition. Flies were 3 days old. Genotype: repo-GAL4, UAS-GFAP^R79H/+. (e) Overexpression of Nos (Nos OE) increases, while reduced Nos expression (Nos RNAi) decreases the total number of TUNEL-positive cells (total, left), including both dying neurons (middle) and glia (right) in GFAP^R79H transgenic flies. **P<0.0001, F=13.18; 9.627; 17.06; df=23; 23; 23; n=6 per genotype. Flies were 20 days old. Genotypes are indicated in the figure label. Driver: repo-GAL4. +: repo-GAL4, UAS-GFAP^R79H/+. Statistical tests: one-way ANOVA with Tukey's multiple comparison test in a,c and e; χ²-test in b and d.