Movie 2.

Reduced protrusion stability in fmr1 mutant PyrNs. Timelapse recordings of the three EGFP-caax labeled PyrN apical dendrites from one WT (left) and two fmr1 mutant (middle and right) larvae. fmr1 mutant PyrN at middle exhibited a moderate reduction in dendrite arbor size, whereas fmr1 mutant PyrN at right exhibited severely impaired dendrite growth. Compare short and stable spines on WT to the motile filopodia present on the mutant PyrNs. Asterisk indicates a 1 hr interval when part of the middle dendrite was below the image acquisition volume due to specimen drift.