Figure 2. Perturbation of SMN in the nervous system disrupts normal motor behavior.

(A) Various parameters of locomotion as measured by the Buridan's assay are shown for neuronal perturbations of SMN using the elav^C155-GAL4 driver line. SMN knockdown using two RNAi lines results in decreased speed, distance covered and overall activity, while the number of pauses is increased significantly without affecting mean pause length. Western blot from adult heads shows strong over-expression (SMN-OE) and significant but not complete knock down (SMN-RNAi) of SMN protein levels in adult heads (a predominantly neuronal population). (B) Single representative fly traces (left circles) and cumulative occupancy plots (right circles with heat maps) show disrupted locomotor behavior following pan-neuronal knockdown of SMN. (C) Muscle perturbation of SMN using the how^24B-GAL4 driver line. The number of pauses is significantly increased following either over-expression or knockdown of SMN in the mesoderm. Western blot of protein extract from adult thorax shows strong over-expression (SMN-OE) and significant but not complete knock down of SMN in muscle tissue (SMN-RNAi). (D) Single fly tracks and cumulative occupancy plots show mild impairment of locomotion. Note that muscle expression of SMN-RNAi-N4 is pupal lethal as reported previously. 10 individual animals that are 5–6 days old are tested for each genotype. Error bars are SEM, double asterisks represent p<0.01 as tested by ANOVA.