Root localizes to the ciliary rootlet in embryonic Ch and Es neurons. (A) Schematic view of the embryonic Ch neuron with structural protein markers. Bb, basal body; Cd, ciliary dilation; Ci, cilium; Cr, ciliary rootlet; Sr, scolopale rod; Tz, transition zone. (B) Endogenous Root is expressed in the embryonic PNS. Antibody 22C10 recognizes Futsch, a PNS neuron marker. (C) Root is expressed in both Ch and Es neurons. Boxed and circled areas indicate Ch neurons and Es neurons, respectively, which are illustrated as pink bars and blue circles in the cartoon on the right. The schematic is adapted from Orgogozo and Grueber (2005) and the names of type I sensory neurons are indicated. (D) Root localizes to the rootlet in Ch neurons. Endogenous Root or GFP tagged Root is counterstained with the PNS marker 22C10 or the following ciliary markers (open arrows): Plp, Ana1, and Cnn mark the Bb; Cby marks the Tz; CG11356 marks the axoneme; and 21A6/Eys marks the cilium proximal end and the extracellular region right below the ciliary dilation. Root also localized to a focus, together with Cnn and Ana1, distal to the basal body, in an unknown structure that might be the ciliary dilation (asterisks). In control +/+ or Root⁶⁶/TM6B, Root resides at a structure consistent with the ciliary rootlet (solid arrows) that extends from the base of the basal body, passes through the dendrite, and reaches the cell body. In homozygous Root⁶⁶ or hemizygous Root⁶⁶/Df, Root is absent from the rootlet (solid arrowheads). However, the morphologies of mutant neurons and scolopale rods appear normal, as marked by 22C10 and actin, respectively; the localizations of Cby and 21A6 are also unaffected (open arrows). Mutant embryos are from Root heterozygous parents and distinguished by Root antibody staining. Bars: (B) 100 µm; (C and D) 10 µm.