Fig. 3.

Flies expressing Aβ_1–42 are more sensitive to oxidative stress and have higher levels of oxidative damage. Supplementing the fly food with 10% v/v H₂O₂ for 72:00 h (a, shaded bars) was specifically toxic to flies expressing Aβ_1–42, significantly reducing their survival as compared with flies expressing Aβ_1–40 (a, elav-Gal4 UAS-Aβ_1–42 vs. elav-Gal4 UAS-Aβ_1–40, P < 0.05). H₂O₂ treatment did not reduce the survival of Aβ_1–40 as compared with control flies (a, elav-Gal4 w¹¹¹⁸ vs. elav-Gal4 UAS-Aβ_1–40). The differences in survival at 72:00 h were not due to toxicity of the Aβs because in the absence of H₂O₂ there was no difference in survival between any of the groups (open bars). Flies expressing Aβ_1–42, but not flies expressing Aβ_1–40 or control flies, exhibited markers of oxidative stress. Measurement of carbonyl groups (nm/mg head protein extract) demonstrated that flies expressing Aβ_1–42 had a significantly higher carbonyl load than control flies (b, elav-Gal4 w¹¹¹⁸ vs. elav-Gal4 UAS-Aβ_1–42, P < 0.05). In flies expressing Aβ_1–40 the carbonyl load was not significantly increased (b, elav-Gal4 UAS-Aβ_1–40 vs. elav-Gal4 w¹¹¹⁸) above control levels. The data are representative of three independent Aβ₄₂ transgenic lines. Independent Student’s t-test result (*P < 0.05, **P < 0.01).