Fig. 6. Increased Rheb-TOR signaling through S6K promotes early senescence of negative geotaxis, the ability to travel against gravity. Although flies overexpressing Rheb (hs>Rheb) show no defect in this behavior 5 days after eclosion, hs>Rheb flies exhibit significant decrease in negative geotaxis 30 days post-eclosion (P=0.0002). Furthermore, co-overexpression of dominant-negative S6K^KQ can rescue this defect in hs>Rheb flies. After 30 days, the mean percentage of flies traveling 5cm in 10 seconds is 93% for hsGAL4/w flies, 33% for hs>Rheb flies and 80% for hs> Rheb; S6K^KQ flies (P=0.0705, NS). Error bars represent the s.d. Statistical comparison (T-test): P values are based on comparison of the overexpressor with the control (hsGAL4/w).