Figure 6.

Ras1 hyperactivation in the MBs contributes to the learning deficiency of dNf1 nulls. A, Confocal images illustrate the distribution of Ras1 in the MBs of adult flies. Ras1-Gal4 drives the expression of UAS-mCD8GFP, especially in the α/β MB lobes (Aa–Ad), the γ lobe (Aa, arrowhead), and at lower levels in the α/′β′ lobes, where it colocalizes with Leo that marks all MB lobes (Aa,Ab,Ad, arrow in the marked boxes). Marked boxes represent higher magnification of the α/α′ lobes. B–G, Performance assessment after conditioning in control (white bars), mutant (black bars), and experimental (gray bars) animals. The genotypes of all animals are indicated below each bar. Data are mean ± SEM. G80^ts indicates the ubiquitously expressed temperature-sensitive Gal4 repressor Tub-Gal80^ts. B, Adult-specific dRas1 abrogation within the OK72 marked neurons at the exclusion of MB expression (second gray bar) partially restores learning in dNf1^E2 homozygotes. *Statistically significant difference of the experimental from mutant flies. C, dRas1 abrogation in MB neurons (Leo-Gal4 driver) during adulthood rescues the dNf1^E2 learning deficits. *Statistically significant difference of the experimental from mutant flies. D, dRas1 abrogation in MB neurons (c772-Gal4 driver) during adulthood improves the dNf1^E2 learning deficit. §Statistical difference of the experimental from the mutant flies (p = 0.0312). E, F, Adult-specific abrogation of Ras1 (UASRas1^Ri) in MB neurons does not yield learning deficits in control flies. The performance of animals with reduced Ras1 within MBs was not significantly different from that of controls both after 6 (E) and 3 (F) CS-US pairings. G, Overexpression of the constitutively active Ras1 (UASRas1^v12) in the MBs of WT adult flies yields learning deficits. ^#Statistically significant difference of the experimental from the control groups. H, Representative Western blot of head lysates from adult flies expressing pan-neuronally a constitutively active form of Ras1 (UASRas1^v12) under Elav-Gal4;Gal80^ts using an antibody against phosphorylated ERK (p-ERK), revealing elevated active kinase compared with control animals. The amount of total-ERK protein is not affected. The genotypes of animals used are indicated above the immunoblot. Tubulin levels serve as loading control.